Search

[EN] The effect of the dietary inclusion of lemon leaves and rice straw by-products on the quality characteristics of goats' milk and cheese was evaluated. Twenty-six Murciano-Granadina goats were used in a crossover design experiment; milk from each experimental group was collected to produce 60-days matured cheeses. Fat and dry matter content was higher in milk and cheeses from the diet containing by-products; medium-chain fatty acids and total free fatty acids were lower. Triangle tests revealed significant differences in the organoleptic characteristics of the cheeses between diets. However, when sensory attributes differentiating cheeses were evaluated individually, differences did not become significant. The inclusion of lemon leaves and rice straw in balanced diets with soya oil could be beneficial, as it does not appear to adversely affect the quality of milk and related mature cheeses, contributing to the reduction of the cost of the diet and the recycling of agricultural by-products. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

[EN] Reducing methane emissions in ruminants with the recycling of agro-industrial by-products is of great importance today. Pruning waste from citrus trees is currently burned or incorporated into soil. Regarding rice straw, this waste is traditionally eliminated through controlled burning, releasing into the atmosphere large amounts of greenhouse gases as well. The aim of this study was to convert this recovered waste into a new animal feed capable of reducing methane emissions in ruminants. The interest in use waste by-products for ruminant nutrition is increasing. Therefore, we replace the beet pulp and cereal straw from dry-non-pregnant goats' diet with orange leaves and rice straw with the objective of studying their effect upon intake, digestibility, energy efficiency, carbon and nitrogen balance, and methane emissions. Considering the huge quantities of crops by-products and pruning waste such as rice straw and citrus leaves produced annually worldwide, and their potential pollution capacity, recycling as feed for livestock is an alternative. The objective was to study these by-products effect on energy balance and methane emissions in 10 Murciano-Granadina goats at maintenance. The control diet (CTR) included barley straw and beet pulp while the experimental diet (ORG) consisted of rice straw and orange leaves. Differences were found for energy intake (248 kJ/kg of BW0.75 greater for CTR than ORG). The intake of metabolizable energy was 199 kJ/kg of BW0.75 lower in ORG than CTR, and the energy efficiency was higher with CTR (0.61) than ORG (0.48). Protein retained in the body was 9 g/goat greater with CTR than ORG, and fat retention in the body was approximately 108 g/goat greater with CTR than ORG. Despite more unfavorable energy balance in response to feeding ORG than CTR, the retention of body energy was always positive. Reductions in CH4 emissions were detected when goats were fed ORG diet (from 22.3 to 20.0 g/d). Overall results suggested that feeding

[EN] The aim of this study was to evaluate the effects of incorporating rice straw and orange leaves into the diets for goats. Ten Murciano-Granadina goats at mid lactation weighing 45 +/- 0.3 kg were used in a crossover design. Two isoproteic and isoenergetic diets (180 g/kg DM and 17 MJ/kg DM, respectively) with alfalfa hay as forage source (33% of DM) were fed. A control diet (CON) incorporated barley as energy source and soy hulls as fiber component. The experimental diet (ORG) replaced barley and soy hulls with orange leaves (19% on DM basis), rice straw (12%, on DM basis) and soya oil (2%). Peas and horsebeans were the protein source in both diets. Each goat received the 2 treatments in 2 periods. Goats were fed the experimental diets and after 14 d on their respective treatments moved to individual metabolism cages for another 7 d. Subsequently, feed intake, total fecal and urine output and milk yield were recorded daily over the first 5 d. During the next 2 d ruminal fluid and blood samples were collected, and then individual gas-exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. No differences in dry matter intake were detected, and apparent total-tract digestibility was greater in CON than ORG. Efficiency of metabolizable energy intake for milk and maintenance also was lower in response to ORG (0.65 vs. 0.63), with energy balance being negative (-12 kJ/kg of BW0.75) due to mobilization of fat (-16 g/animal vs. 68 g/animal for ORG and CON, respectively). Although actual milk yield was lower in goats fed ORG (2.32 vs. 2.06 kg/d, respectively), energy-corrected milk did not differ (2.81 kg/d on average). In terms of milk quality, milk fat content, and concentrations of monounsaturated (18.54 vs. 11.55 g/100 g milk fat) and polyunsaturated fatty acids (5.75 vs. 3.99 g/100 g milk fat) were greater in goats fed ORG. Based on various indices, the milk produced by ORG would be less atherogenic and thrombogeni

[EN] Mechanisms controlling immune function of dairy cows are dysregulated during heat stress (HS). Methyl donor supply-methionine (Met) and choline (Chop-positively modulates innate immune function, particularly antioxidant systems of polymorphonuclear leukocytes (PMN). The objective of this study was to investigate the effect of Met and Chol supply in vitro on mRNA abundance of genes related to 1-carbon metabolism, inflammation, and immune function in short-term cultures of PMN isolated from mid-lactating Holstein cows in response to heat challenge. Blood PMN were isolated from 5 Holstein cows (153 +/- 5 d postpartum, 34.63 +/- 2.73 kg/d of milk production; mean +/- SD). The PMN were incubated for 2 h at thermal-neutral (37 degrees C; TN) or heat stress (42 degrees C; HS) temperatures with 3 levels of Chol (0, 400, or 800 mu g/mL) or 3 ratios of Lys:Met (Met; 3.6:1, 2.9:1, or 2.4:1). Supernatant concentrations of IL-1 beta, IL-6, and tumor necrosis factor-alpha were measured via bovine-specific ELISA. Fold-changes in mRNA abundance were calculated separately for Chol and Met treatments to obtain the fold-change response at 42 degrees C (HS) relative to 37 degrees C (TN). Data were subjected to ANOVA using PROC MIXED in SAS (SAS Institute Inc., Cary, NC). Orthogonal contrasts were used to determine the linear or quadratic effect of Met and Chol for mRNA fold-change and supernatant cytokine concentrations. Compared with PMN receiving 0 mu g of Chol/mL, heat-stressed PMN supplemented with Chol at 400 or 800 mu g/mL had greater fold-change in abundance of CBS, CSAD, GSS, GSR, and GPX1. Among genes associated with inflammation and immune function, fold-change in abundance of TLR2, TLR4, IRAK1, IL1B, and IL10 increased with 400 and 800 mu g of Chol/mL compared with PMN receiving 0 mu g of Chol/mL. Fold-change in abundance of SAHH decreased linearly at increasing levels of Met supply. A linear effect was detected for MPO, NFKB1, and SOD1 due to greater fold-change in abu

[EN] Methionine (Met) and arginine (Arg) regulate casein protein abundance through alterations in activity of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. A potential role for the circadian clock network on the regulation of protein synthesis, partly via activity of mTORC1, has been highlighted in non-ruminants. The main objective of the study was to determine in ruminant mammary cells alterations in mRNA, protein abundance and phosphorylation status of mTORC1-related upstream targets, circadian clock proteins, and protein kinase AMP-activated catalytic subunit alpha (AMPK) in relation to alpha-s1-casein protein (CSN1S1) abundance in response to greater supply of Met and Arg alone or in combination. Primary bovine mammary epithelial cells (BMEC) were incubated for 12 h in a 2 x 2 arrangement of treatments with control media (ideal profile of amino acids, IPAA), or media supplemented with increased Met (incMet), Arg (incArg), or both (incMet + incArg). Data were analyzed testing the main effects of Met and Arg and their interaction. Among 7 amino acid (AA) transporters known to be mTORC1 targets, increasing supply of Arg downregulated SLC1A5, SLC3A2, SLC7A1, and SLC7A5, while increasing supply of Met upregulated SLC7A1. mRNA abundance of the cytosolic Arg sensor (CASTOR1) was lower when supply of Arg and Met alone increased. p-TSC2 (TSC complex subunit 2) was greater when the Arg supply was increased, while the phosphoralation ratio of p-AKT (AKT serine/threonine kinase 1):total (t) AKT and p-AMPK:tAMPK were lower. In spite of this, the ratio of p-mTOR:tmTOR nearly doubled with incArg but such response did not prevent a decrease in CSN1S1 abundance. The abundance of period circadian regulator 1 (PER1) protein nearly doubled with all treatments, but only incMet + incArg led to greater clock circadian regulator (CLOCK) protein abundance. Overall, data suggest that a greater supply of Met and Arg could influence CSN1S1 synthesis of BMEC thro

[EN] The main objective of this study was to develop a dynamic energy balance model for dairy goats to describe and quantify energy partitioning between energy used for work (milk) and that lost to the environment. Increasing worldwide concerns regarding livestock contribution to global warming underscore the importance of improving energy efficiency utilization in dairy goats by reducing energy losses in feces, urine and methane (CH4). A dynamic model of CH(4)emissions from experimental energy balance data in goats is proposed and parameterized (n= 48 individual animal observations). The model includes DM intake, NDF and lipid content of the diet as explanatory variables for CH(4)emissions. An additional data set (n= 122 individual animals) from eight energy balance experiments was used to evaluate the model. The model adequately (root MS prediction error,RMSPE) represented energy in milk (E-milk;RMSPE = 5.6%), heat production (HP;RMSPE = 4.3%) and CH(4)emissions (E-CH4; RMSPE = 11.9%). Residual analysis indicated that most of the prediction errors were due to unexplained variations with small mean and slope bias. Some mean bias was detected for HP (1.12%) and E-CH4(1.27%) but was around zero for E-milk (0.14%). The slope bias was zero for HP (0.01%) and close to zero for E-milk (0.10%) and E-CH4(0.22%). Random bias was >98% for E-CH4, HP and E-milk, indicating non-systematic errors and that mechanisms in the model are properly represented. As predicted energy increased, the model tended to underpredict E-CH(4)and E-milk. The model is a first step toward a mechanistic description of nutrient use by goats and is useful as a research tool for investigating energy partitioning during lactation. The model described in this study could be used as a tool for making enteric CH(4)emission inventories for goats.

[EN] Context. Goats contribute to global warming through emission of nitrous oxide from urine and faeces. To reduce nitrogen (N) excretion, improvements of N efficiency of goats is necessary. Aims. The aim of the present study was to develop and evaluate a dynamic mechanistic research-oriented model that explicitly represents N partition into faeces, urine and milk in dairy goats fed total mixed rations. Methods. Data from five N-balance dairy-goat experiments were used to develop a mechanistic dynamic model of post-absorptive N partition. Various representations considering either mass action or Michaelis-Menten kinetics of N usage for milk were proposed. Key results. The data for faecal and urine N responses were best fit by a straight line; whereas, data for milk N responses were best fit by curvilinear saturating curve. The model with curvilinear saturating curve had more precise parameter estimates, with the predicted N excretion in faeces (15.6 g/day), urine (15.4 g/day) and milk N output (11.7 g/day) being very close to the observed values, namely, 15.31 g N/day in faeces, 18.78 g N/day in urine and 12.24 g N/day in milk. Independent datasets with 12 studies were used to evaluate the model. The model tended to under-predict faecal N outflow at a lower N intake level and urinary N outflow at a higher N intake level, with the lowest mean bias for milk N outflow. Conclusions. The final chosen model was adequate to represent faecal, urinary and milk N outflows in dairy goats. Implications. The model has provided a mechanistic description of N usage, which is useful to frame and test hypotheses of physiological regulation of N use by goats, and focus on a more efficient transfer of dietary N into milk, reducing the N excretion in faeces and urine.

[EN] Dairy cows with high body condition score (BCS) in late prepartum are more susceptible to oxidative stress (OS). Nuclear factor erythroid 2-like 2 (NFE2L2) is a major antioxidant transcription factor. We investigated the effect of precalving BCS on blood biomarkers associated with OS, inflammation, and liver function, along with mRNA and protein abundance of targets related to NFE2L2 and glutathione (GSH) metabolism in s.c. adipose tissue (SAT) of periparturient dairy cows. Twenty-two multiparous Holstein cows were retrospectively classified into a high BCS (HBCS; n = 11, BCS ¿3.5) or normal BCS (NBCS; n = 11, BCS ¿3.17) on d 28 before parturition. Cows were fed a corn silage- and wheat straw-based total mixed ration during late prepartum, and a corn silage- and alfalfa hay-based total mixed ration postpartum. Blood samples obtained at ¿10, 7, 15, and 30 d relative to parturition were used for analyses of biomarkers associated with inflammation, including albumin, ceruloplasmin, haptoglobin, and myeloperoxidase, as well as OS, including ferric reducing ability of plasma (FRAP), reactive oxygen species (ROS), and ß-carotene. Adipose biopsies harvested at ¿15, 7, and 30 d relative to parturition were analyzed for mRNA (real-time quantitative PCR) and protein abundance (Western blotting) of targets associated with the antioxidant transcription regulator nuclear factor, NFE2L2, and GSH metabolism pathway. In addition, concentrations of GSH, ROS and malondialdehyde were measured. High BCS cows had lower prepartum dry matter intake expressed as a percentage of body weight along with greater BCS loss between ¿4 and 4 wk relative to parturition. Plasma concentrations of ROS and FRAP increased after parturition regardless of treatment. Compared with NBCS, HBCS cows had greater concentrations of FRAP at d 7 postpartum, which coincided with peak values in those cows. In addition, NBCS cows experienced a marked decrease in plasma ROS after d 7 postpartum, while HBCS cows m

[EN] Peripartal cows mobilize not only body fat but also body protein to satisfy their energy requirements. The objective of this study was to determine the effect of prepartum BCS on blood biomarkers related to energy and nitrogen metabolism, and mRNA and protein abundance associated with AA metabolism and insulin signaling in subcutaneous adipose tissue (SAT) in peripartal cows. Twenty-two multiparous Holstein cows were retrospectively classified into a high BCS (HBCS; n = 11, BCS >= 3.5) or normal BCS (NBCS; n = 11, BCS <= 3.17) group at d 28 before expected parturition. Cows were fed the same diet as a total mixed ration before parturition and were fed the same lactation diet postpartum. Blood samples collected at -10, 7, 15, and 30 d relative to parturition were used for analyses of biomarkers associated with energy and nitrogen metabolism. Biopsies of SAT harvested at -15, 7, and 30 d relative to parturition were used for mRNA (real timePCR) and protein abundance (Western blotting) assays. Data were subjected to ANOVA using the MIXED procedure of SAS (v. 9.4; SAS institute Inc., Cary, NC), with P <= 0.05 being the threshold for significance. Cows in HBCS had greater overall plasma nonesterified fatty acid concentrations, due to marked increases at 7 and 15 d postpartum. This response was similar (BCS x Day effect) to protein abundance of phosphorylated (p) protein kinase B (p-AKT), the insulin-induced glucose transporter (SLC2A4), and the sodium-coupled neutral AA transporter (SLC38A1). Abundance of these proteins was lower at -15 d compared with NBCS cows, and either increased (SLC2A4, SLC38A1) or did not change (p-AKT) at 7 d postpartum in IIBCS. Unlike protein abundance, however, overall mRNA abundances of the high-affinity cationic (SLC7A1), proton-coupled (SLC96A1), and sodium-coupled amino acid transporters (SLC,98,42) were greater in IIBCS than NBCS cows, due to upregulation in the postpartum phase. Those responses were similar to protein abundance of p

[ES] En el actual trabajo se quiere evaluar el efecto de subproductos de residuos de poda de cítricos de naranja y limón y de paja de arroz en cabras Murciano-Granadinas en mantenimiento. Para ello se diseñaran dos experimentos independientes de 10 animales cada uno, los cuales serán subdivididos en dos grupos donde 5 animales se alimentarán de una dieta Control y los otros 5 de una dieta basada en los residuos mencionados. Se les realizará una digestibilidad y una respirometría para valorar el efecto de las dietas en la ingestión, la digestibilidad, el balance energético, el balance de carbono y nitrógeno y la emisión de metano de los animales. Los resultados obtenidos han seguido una tendencia similar en ambos experimentos, siendo los datos más relevantes una eficiencia energética positiva en las tres dietas (de un 44% para la dieta Control, un 23% para la dieta Naranja y un 26% para la dieta Limón), una digestibilidad y energía metabolizable ingerida en las dietas de cítricos menor que en la dieta Control y una cantidad de carbono y nitrógeno excretado en heces y orina mayor que en la dieta Control. También la cantidad de metano emitido por las cabras en gramos por día resultó un 2,3% menor en la dieta Naranja que en la dieta Control, y un 1,9% menor en la dieta Limón que en la dieta Control., [EN] In the current work we want to evaluate the effect of by-products of pruning residues of orange and lemon citrus and rice straw in Murciano-Granadine goats in maintenance. For this, two independent experiments of 10 animals each will be designed, which will be subdivided into two groups where 5 animals will feed on a ‘Control’ diet and the other 5 on a diet based on the above-mentioned residues. A digestibility and respirometry will be performed to assess the effect of diets on intake, digestibility, energy balance, carbon and nitrogen balance and methane emission from animals. The results obtained have followed a similar trend in both experiments, the most relevant data being a positive energy efficiency in the three diets (44% for the Control diet, 23% for the Orange diet and 26% for the Lemon diet), a digestibility and metabolizable energy ingested in citrus diets less than in the Control diet and an amount of carbon and nitrogen excreted in feces and urine greater than in the Control diet. Also the amount of methane emitted by goats in grams per day was 2.3% lower in the Orange diet than in the Control diet, and 1.9% lower in the Lemon diet than in the Control diet.

[EN] The objective of this experiment was to study the effects of substituting alfalfa with orange leaves on energy, nitrogen and carbon balance, methane emission, and milk performance in dairy goats. Ten Murciano-Granadina dairy goats in mid lactation (43.5 +/- 3.59 kg of body weight [BW]) were selected in a crossover design experiment, where each goat received two treatments in 2 periods. One group of five goats was fed a mixed ration with 450 g of pelleted alfalfa and 550 g of pelleted concentrate/kg of dry matter (ALF diet), and the other diet replaced alfalfa with orange leaves (ORG diet). Inclusion of ORG than ALF diet reduced (P = 0.041) dry matter intake. The metabolizable energy intake was identical between treatments (901 kJ/kg of BW0.75, on average) and, the efficiency of metabolizable energy for milk production was 0.73. Retention of energy was lower (P = 0.001) in ORG diet than ALF diet. Carbon and nitrogen intake (P = 0.022 and P = 0.004, respectively) was greater for diet ALF than ORG, with no differences in milk carbon and nitrogen. The ORG diet reduced (P = 0.037) milk fat 3 g/kg, and CH4 (P = 0.001) 6 g/d. One of the milk fatty acids positively correlated with CH4 production was C16:0; it was greater (P < 0.05) in ALF than ORG diet. When CH4 was expressed over OM digestibility and milk basis, differences were preserved. Results suggest that orange leaves are effective in reducing CH4 emission without detrimental effect on nutrients balance and milk yield.

[EN] Methane (CH4) is a natural by-product of microbial fermentation in the rumen and is a powerful greenhouse gas. An open-circuit indirect calorimetry system for continuous determination of CH4 and CO2 production and O-2 consumption and, thereafter, heat production (HP) calculation for small ruminants was described and validated. The system consisted of a computerized control, data acquisition and recording system for gases and air flux. The average value +/- standard deviation for the calibration factors in the system were 1.005 +/- 0.0007 (n = 6), 1.013 +/- 0.0012 (n = 6) and 0.988 +/- 0.0035 (n = 6) for O-2, CO2 and CH4, respectively. Calibration factors close to 1 confirmed the absence of leaks in the indirect calorimetry system. In addition, an experimental test with 8 goats at mid lactation was conducted to validate the system. The repeatability for CH4 and heat production measured with the open-circuit indirect calorimetry system was 79% and 61%, respectively. Daily average HP measured by indirect calorimetry (Respiration Quotient method) was close to the average HP determined from Carbon-Nitrogen balance (CN method), accounting for 685 and 667 kJ per kg metabolic body weight, respectively. Therefore, discrepancies averaged 1.92%, a rather satisfactory value considering the substantial amount of technical and analytical work involved. The close agreement found between both methods can be considered as being indicative of the absence of systematic error. Two diets with different forage were tested: 40% was either alfalfa hay (HAY) or alfalfa silage (SIL), and the proportion of concentrate was the same in both groups (60%). The experimental trial shown that HP and CH4 were higher in HAY than SIL diet (differences between treatments of 28 kJ of HP per kg of metabolic body weight and 7.1 L CH4/day were found). The data acquisition and recording device developed improved the accuracy of the indirect calorimetry system by reducing the work involved in managing ou

[EN] The objective of the study was to develop a univariate model for analyzing energy balance data from lactating goats at mid lactation and determine maintenance requirements and partial efficiencies of energy utilization. Energy balance data from eight studies involving lactating Murciano-Granadina goats fed total mixed diets, which accounted for a variation in metabolizable energy (MEI) intake, milk energy output (EI), and tissue energy balance, were used. The database included records obtained by indirect calorimetry. Data were adjusted with a mixed model that included the study as a random effect. Then, two multivariate linear models were obtained: metabolizable and net energy models. The metabolizable model was MEI=ß0+ß2E1+ß3Tg+ß4T1+¿ and the net energy model was E1=ß0+ß1MEI+ß2Tg+ß3T1+¿; where ß0, ß1, ß2 and ß3 were the parameters, Tg was tissue energy retention and Tl the milk energy derived from body stores. For a better fitted proposed model, net energy for maintenance (NEm) was 283 kJ/kg of Body Weight 0.75 (BW) per day, and the efficiency of utilization of ME for lactation (k1), body weight gain (kg) and body tissue mobilization for milk production (kt) were 62%, 83% and 78%, respectively. Maintenance requirements and partial efficiencies for milk production and tissue energy mobilization were similar to the values proposed by INRA (2018). The increase in the efficiency of utilizing dietary energy for gain, compared with other feeding systems, was partially attributed to the stage of lactation, due to that goats were feeding at mid lactation

[ES] De un rebaño de 150 cabras de raza Murciano-Granadina en lactación se seleccionarán 10 cabras, de las cuales 5 comerán una dieta control y las otras 5 otra que incorpora paja de arroz y hoja de naranjo procedente de los residuos de la poda. Mediante jaulas metabólicas y calorimetría indirecta se calculará la digestibilidad, el balance de nutrientes y el rendimiento lechero, con el objetivo de valorar si la incorporación de estos subproductos agroindustriales mantienen el rendimiento productivo. No se observaron diferencias significativas en la ingestión de materia seca entre las dos dietas, manteniendo una ingestión media entre los dos grupos de 2,23 kg/d por animal. No se observaron cambios significativos en los parámetros de mayor importancia en el ambiente ruminal, presentando alguna diferencia significativa en los ácidos grasos volátiles de menor proporción. En el caso del balance energético ha sido superior en la dieta control, en cambio ambas dietas han proporcionado un balance energético positivo. La producción de leche presentó diferencias significativas, siendo inferior en la dieta con hoja de naranjo y paja de arroz, pero al mismo tiempo presentando un 1% más de materia seca y grasa en la leche. Se observaron diferencias significativas en el perfil de ácidos grasos en la grasa de la leche, siendo mayor la presencia de ácidos grasos insaturados en la leche de los animales alimentados con la dieta con hojas de naranja y paja de arroz., [EN] From a herd of 150 goats of Murciano-Granadina breed, 10 goats will be selected, of which 5 will eat a control diet and the other 5 will incorporate rice straw and orange leaf from the pruning waste. Through metabolic cages and indirect calorimetry, digestibility, nutrient balance and milk yield will be calculated, in order to assess whether the incorporation of these agro-industrial by-products maintain productive performance. No significant differences were observed in the ingestion of dry matter between the two diets, maintaining an average ingestion between the two groups of 2,23 kg/d per animal. No significant changes were observed in the most important parameters in the ruminal environment, presenting some significant difference in the volatile fatty acids with less proportion. n the case of the energy balance it has been superior in the control diet, however both diets have provided a positive energy balance. Milk production showed significant differences, being lower in the diet with orange leaf and rice straw, but at the same time presenting 1% more dry matter and fat in milk. Significant differences were observed in the profile of fatty acids in milk fat, the presence of unsaturated fatty acids in the milk of animals fed the diet with orange leaves and rice straw being greater.

[ES] De un rebaño de 150 cabras de raza Murciano-Granadina en lactación se seleccionarán 14 cabras, de las cuales 7 comerán una dieta control y las otras 7 otra que incorpora paja de arroz y hoja de limón procedente de los residuos de la poda. Con una metodología validada y con un equipo de calorimetría indirecta diseñado en la UPV se calculará el balance energético, aprovechamiento de la dieta, y rendimiento lechero de las cabras. Con estos resultados se pretende obtener, a partir del coste energético, unos indicadores técnicos de aprovechamiento de la dieta por cabras lecheras., [EN] From a herd of 150 goats of Murciano-Granadina breed, 14 goats will be selected, of which 7 will eat a control diet and the other 7 will incorporate rice straw and lemon leaf from the pruning waste. With a validated methodology and with an indirect calorimetry equipment designed at the UPV, the energy balance, the use of the diet, and the milk yield of the goats will be calculated. With these results, it is intended to obtain, from the energy cost, technical indicators of the use of the diet by dairy goats.

El uso de restos de poda para alimentación del ganado no se ha evaluado nutritivamente y tiene la ventaja de eliminar la necesidad de elaborar costosos programas de eliminación de residuos. Es por esto, que el objetivo de este trabajo es estudiar el efecto sobre la digestibilidad, el balance energético y el rendimiento lechero, tras la sustitución de la alfalfa por restos de poda de limonero peletizado, en concreto las hojas, en la ración diaria suministrada a cabras, de la raza Murciano-Granadina, en mitad de lactación. Para ello se seleccionaron 10 cabras de la raza Murciano-Granadina con un peso vivo 44,1 ± 4,47 kg, en mitad de lactación. Se dividieron los animales en dos grupos de cinco animales en cada uno, los animales de cada uno de los dos grupos tomaron el mismo pienso. Solo fue diferente el forraje; a un grupo se le dio heno de alfalfa y al otro grupo hoja de limonero. Los resultados obtenidos relativos a la ingestión y al coeficiente de digestibilidad aparente de las dietas experimentales muestran que hubo diferencias significativas en la ingestión total del forraje pero no en pienso. El consumo de hoja de limón fue menor y la digestibilidad total de la ración fue superior, a excepción de la digestibilidad de las fibras. También, se puede observar que hay diferencias significativas en la ingestión de energía bruta, siendo mayor esta ingestión en el grupo de animales que tenían alfalfa, ya que la ingestión de materia seca fue mayor en este grupo. Debido a la menor digestibilidad en la dieta ALFALFA se produjeron mayores pérdidas energéticas en las heces. A pesar de las diferencias significativas en la energía de las heces, orina y la producción de metano entre las dietas, no se observaron diferencias en la energía metabolizable. La cantidad de energía perdida en forma de metano con respecto a la energía bruta ingerida (factor de conversión de metano, Ym) fue superior y significativa para la ración ALFALFA que para la ración LIMÓN. Esa mayor producción de m, The use of pruning remains for livestock feed has not been evaluated nutritionally and has the advantage of eliminating the need to develop costly waste disposal programs. The aim of this work is to study the effect on digestibility, energy balance and milk yield, after the replacement of alfalfa by pelleted lemon pruning remains, specifically the leaves, in the daily ration supplied to goats in the middle of lactation. For this research 10 goats of the Murciano-Grenadine breed, with a live weight between 44.1 ± 4.47 kg in the middle of lactation, were selected. The animals were divided into two groups of five animals each. The animals took the same feed, but only the forage was different because a group was given alfalfa hay and the other group lemon leaf. The results obtained regarding the ingestion and the apparent digestibility coefficient of the experimental diets show that there were significant differences in the total ingestion of the forage but not in the feed. The consumption of lemon leaf was lower and the total digestibility of the ration was higher, except for the digestibility of the fibers. Moreover, it can be observed that there are significant differences in the ingestion of gross energy, being this ingestion higher in the group of the animals that had alfalfa, since the ingestion of dry matter was higher in this group. Due to the lower digestibility in the ALFALFA diet, greater energy losses were produced in the feces. Despite significant differences in fecal energy, urine and methane production between diets, no other differences in metabolizable energy were observed. The amount of energy lost in the form of methane with respect to the gross energy ingested (methane conversion factor, Ym) was higher and significant for the ALFALFA ration than for the LEMON ration. This higher methane production was due to a higher consumption of fiber. No significant differences were observed for the VFA and pH between the rations. The N-NH3 content of the rumen w

[EN] A dynamic model of methane (CH4) emission in goats was proposed and parameterized from energy balance experimental data. The model focused on dry matter intake and fat content of the diet as explanatory variables for CH4 emission. Experimental and literature data were used to develop the model. Then, data (n = 123) from five energy balance experiments were used to evaluate the model. The model was adequate to represent energy in milk, heat production and CH4 emissions. Residual analysis showed that most of the prediction errors were due to unexplained variations with small mean and slope bias (around zero with exception of CH4; <6%). The model tends to over-predict energy in CH4 at higher energy intake and, energy in milk and heat production at lower energy intake. Random bias was greater than 90%, signifying than more than 90% of the error was non-systematic indicating the mechanism in the model are properly represented. The model is a first step towards a mechanistic description of nutrient use by goats and, useful as a research tool for investigating energy partition in dairy goat systems. The model described in this study should be considered for preparation of enteric CH4 emissions inventories for goats. (c) 2018 The Author. Published by Elsevier B.V.

[ES] Con el objetivo de aprovechar los residuos de la paja de arroz y de la hoja de naranjo para la alimentación animal, se hizo un estudio donde se utilizaron 10 cabras hembras de raza Murciano – Granadina en mitad de la lactación en la Granja Experimental del Departamento de Ciencia Animal de la Universidad Politécnica de Valencia. Las 10 cabras, con un peso medio de 45,35 Kg, se separaron en dos grupos; a cada grupo se le suministraba una dieta diferente. Las dietas estaban formadas por un pienso compuesto peletizado y un forraje. Por tanto, teníamos una dieta control y otra que sustituía cebada por paja de arroz y hoja de naranjo (que hemos denominado dieta naranja). En ambas dietas el forraje fue el mismo, heno alfalfa. Para determinar el balance de carbono y nitrógeno (CN) y el rendimiento lechero se utilizaron jaulas metabólicas. La producción de metano (CH4) se determinó mediante un sistema de calorimetría indirecta en circuito abierto. Se observó diferencias significativas en la ingestión de materia seca del concentrado, siendo las cabras con la dieta naranja las que tuvieron mayor ingestión. La eficacia con la que el carbono ingerido se transforma en leche en ambas dietas fue similar, con un valor medio del 17%. La eficiencia de retención de nitrógeno en leche fue inferior en la dieta naranja frente a control; 18 y 20%, respectivamente. También hubo diferencias significativas entre ambas dietas en los gramos de CH4 producidos al día, siendo 30,2 g/d para la dieta control y 27,2 g/d para la dieta naranja. El factor de conversión del CH4 (Ym) fue 4,4% para la dieta control y 4,0% para la dieta naranja. Con la dieta naranja obtuvo 1,0 punto más de grasa en la leche de cabra que en la dieta control., [EN] In order to take advantage of the residues of rice straw and orange leaf for animal feed, a study was done where they used 10 female goats of Murciano - Grenadine race in the middle of lactation in the Experimental Farm of the Department of Science animal from the Polytechnic University of Valencia. The 10 goats, with an average weight of 45.35 Kg, were separated into two groups; each group was given a different diet. The diets consisted of a pelleted compound feed and a forage. Therefore, we had a control diet and another that replaced barley with rice straw and orange leaf (which we have called orange diet). In both diets the forage was the same, hay alfalfa. To determine the carbon and nitrogen balance (CN) and the milk yield, metabolic cages were used. The production of methane (CH4) was determined by an indirect open-circuit calorimetry system. Significant differences were observed in the ingestion of dry matter in the concentrate, with the goats with the orange diet having the highest ingestion. The efficiency with which the ingested carbon is transformed into milk in both diets was similar, with an average value of 17%. The efficiency of nitrogen retention in milk was lower in the orange versus control diet; 18 and 20%, respectively. There were also significant differences between both diets in the grams of CH4 produced per day, being 30.2 g / d for the control diet and 27.2 g / d for the orange diet. The conversion factor of CH4 (Ym) was 4.4% for the control diet and 4.0% for the orange diet. With the orange diet obtained 1.0 point more fat in goat milk than in the control diet.

[EN] The objective of this experiment was to find out the effect of lemon leaves on energy and C-N balances, methane emission, and milk performance in dairy goats. Lemon leaves were used to replace alfalfa as forage in a diet for Murciano-Granadina goats. Ten Murciano-Granadina dairy goats (44.1 +/- 4.47 kg of BW) in late lactation (185 +/- 7.2 d) were selected in a crossover design experiment, where each goat received 2 treatments in 2 periods. One group was fed a mixed ration with 450 g of pelleted alfalfa per kilogram of DM (ALF diet) and, the other group replaced alfalfa with 450 g of pelleted lemon leaves per kilogram DM (LEM diet). The concentrate was pelleted, being the same for the two groups (forage to concentrate ratio was 45/55). The goats were allocated to individual metabolism cages. After 14 d of adaptation, feed intake, total fecal and urine output, and milk yield were recorded daily over a 5-d period. Then, gas exchange measurements were recorded individually by an open-circuit indirect calorimetry system using a head box. Higher dietary lipids in LEM diet reduced DMI (200 g/d) and energy intake (251 kJ/kg of BW0.75), although no differences between treatments were observed for ME intake (998 kJ/kg of BW0.75, on average) and oxidation of nutrients (64% and 25% for carbohydrates and fat oxidation, respectively, on heat production from oxidation basis). Greater (P < 0.05) milk fat values for C18:2n6t and CLA 9c11t + 9t11c were found in LEM compared with ALF diet. Goats fed LEM diet produced significantly fewer CH4 emissions than ALF diet (18%). Likewise, the use of lemon leaves as forage reduced the amount of CH4 in 2.7 g/kg of milk. Results suggest that lemon leaves are effective in reducing CH4 emission without detrimental effect on milk yield.

[ES] Con el objetivo de estudiar el efecto de la sustitución de la alfalfa granulada (Medicago sativa) por la hoja del naranjo granulada (Citrus sinensis) en la alimentación de rumiantes se realizó el presente estudio en la granja de la Universidad Politécnica de Valencia. Para este se utilizaron 10 cabras de la raza Murciano-Granadina, en estado medio de lactación, con un peso vivo medio de 43,28 kg, divididas en dos grupos de 5 cabras cada uno. A uno de los grupos se le suministró como dieta alfalfa granulada y pienso, al otro grupo hoja de naranja granulada y pienso. Se observaron diferencias significativas en la ingestión de materia seca siendo 1,52 kg/d la media de las dos dietas. El balance de energía fue positivo en las dos dietas, no movilizando reservas y con una energía metabolizable media de 894,23 kJ/kg de PV0,75. Tampoco se obtuvieron diferencias significativas respecto a la producción de leche ni a su composición en grasa y proteína, siendo la media productiva de 1289,91 ml/d. Se encontraron diferencias significativas en la producción de CH4, siendo 17,90 y 16,03 gCH4/d para la dieta de alfalfa y naranja respectivamente, aunque se produce mayor cantidad de CH4 en la dieta de alfalfa, dichas diferencias no se mantienen cuando lo expresamos por Kg de materia seca ingerida o Kg de leche producida., [EN] The present study was done at the farms of the University of Valencia with the goal of studying the effect of the substitution of granulated alfalfa (Medicago sativa) for granulated orange tree leaf (Citrus sinensis) in the nourishment of ruminants. For this one, 10 Murcian-Granadian goats in middle stage of lactation with an average live weight of 43,28 kg. were used, divided in two groups, 5 goats each. One of the groups was administrated granulated alfalfa and feeding stuff as a diet; the other groupwas administrated orange tree leaf and feeding stuff. Significative differences were observed in the ingestion of fry material where 1,52 kg/d was the average of both diets. Energy balance was positive in the two diets, not moving reserves and with an average metabolisable energy of 894,23 kJ/kg of PV0,75 . Significative differences were obtained neither at the dairy production nor at its fat and protein composition, being 1289,91 ml/d the average production. Significative differences were found in the metan production with 17,90 and 16,03 gCH4/d for alfalfa’s and orange’s diet respectively. Even though more CH4 is produced with the alfalfa’s diet, the differences mentioned disappear when we express this on “ingested dry material kg” or “produced milk kg”.

[ES] La alimentación supone un coste muy elevado en las explotaciones de ganado caprino en condiciones intensivas. El empleo de subproductos permite aumentar la disponibilidad de fuentes de alimentos y reducir costes. En el presente trabajo se utilizaron 14 cabras hembras lactantes de raza MurcianoGranadina de la Granja Experimental del Departamento de Ciencia animal de la Universitat Politècnica de València, con un peso medio de 38,45 ± 0,75 kg. Se separaron en dos grupos homogéneos en cuanto a producción y peso y a cada grupo se le suministró una dieta diferente, el grupo Control con un pienso compuesto con mayor proporción de cebada y el grupo Orujo con un pienso al que se incorporó orujo graso de aceituna. Para ambos grupos el forraje fue alfalfa granulada. La proporción forraje:concentrado fue de 40:60. Las pruebas realizadas permitieron estudiar el efecto de la incorporación en la ración de cabras lecheras del orujo graso de aceituna sobre la ingestión, la digestibilidad, el balance energético, el rendimiento lechero y la producción de metano. Los datos obtenidos se analizaron estadísticamente para observar con claridad las posibles diferencias significativas que pudieran existir entre los efectos estudiados de cada una de las dietas. En cuanto a la ingestión de materia seca, fue baja para ambas dietas sin resultar estadísticamente significativa. Debido a esta baja ingestión, las cabras de ambos grupos movilizaron reservas corporales para mantener el rendimiento lechero, en el que no se observaron prácticamente diferencias. La digestibilidad fue superior en la dieta control, debido al mayor consumo de pienso por parte de los animales de este grupo. Se observaron diferencias para los gramos de metano producidos al día, resultando así por el mayor consumo de fibra por parte de los animales del grupo Orujo. A nivel experimental, es esencial cuantificar el consumo o rechazo del ingrediente problema, del que habría que mejorar los aspectos relacionados con la apete, [EN] Feeding is a very high cost for goat farms under intensive conditions. The use of byproducts increases the availability of food sources and reduces costs. In the present work, 14 lactating female goats from the Murciano-Granadina race of the Experimental Farm of the Department of Animal Science of the Universitat Politècnica de València were used, with an average weight of 38.45 ± 0.75 kg. They were separated into two homogeneous groups in terms of production and weight and each group was given a different diet, the Control group with a compound feed with a higher proportion of barley and the Orujo group with a feed containing olive oil. For both groups the forage was granulated alfalfa. The forage: concentrate ratio was 40:60. The tests allowed the study of the effect of the incorporation in the diet of dairy goats of olive pomace on ingestion, digestibility, energy balance, milk yield and methane production. The data obtained were statistically analyzed to clearly observe the possible significant differences that might exist between the studied effects of each of the diets. As for the dry matter intake, it was low for both diets without being statistically significant. Due to this low ingestion, the goats of both groups mobilized body reserves to maintain milk yield, in which practically no differences were observed. The digestibility was higher in the Control diet, due to the higher consumption of feed by the animals of this group. Differences were observed for the grams of methane produced per day, resulting in the higher consumption of fiber by the animals of the Orujo group. At the experimental level, it is essential to quantify the consumption or rejection of the problem ingredient, which would have to improve the aspects related to appetite, as well as to control the quality of the fat contained in it and its state of conservation to avoid it becomes rancid.

Today global warming, climate change and greenhouse gas (GHG) production are topics of great interest as it has been found that different human activities, including agriculture and livestock, are an important source of pollution. Different initiatives with the aim of reducing these emissions and at the same time being productive. Several factors are involved in the plan to reduce GHG emissions from livestock and this study will focus on small ruminants; these factors are such as nutrition, use of supplements, management of manure, etc. This study was carried out at the Polytechnic University of Valencia. It consisted of two phases, first a field phase that was carried out at the university goat farm, and the other a laboratory phase carried out at the Laboratory of the Department of Animal Science The same university. This experiment was carried out with 10 Murciano-Granadina goats weighing between 44,1 ± 4,47 Kg live weight. The objective of this study was to test two types of forage, and to see how these diets affected the parameters of milk and fatty acid production, carbon and nitrogen balance, GHG production. These animals were separated into two groups to analyze the two treatments of this study; T1 (Alfalfa + commercial feed) and T2 (lemon pellet + commercial feed). The results showed significant differences (P <0.05) in nitrogen retained being higher in T1, as well as higher carbon production from CO2 and CH4 of respiration. As for milk production, the protein is higher in T1 and lactose in T2; while methane from both enteral fermentation and manure management in alfalfa treatment was higher in GHG production. In conclusion, other alternative diets should be analyzed; As the waste of agriculture for the feeding of animals since their milk yield was not altered., En la actualidad el calentamiento global, cambio climático y la producción de gases efecto invernadero (GEI), son temas de gran interés pues se ha comprobado que diferentes actividades humanas y entre estas la agricultura y la ganadería son una fuente importante de contaminación, por este motivo existe diferentes iniciativas con el objetivo de reducir estas emisiones y al mismo tiempo ser productivos. Son varios factores los que intervienen en el plan de reducción de emisiones de GEI provenientes de la ganadería y este estudio lo vamos a enfocar en los pequeños rumiantes; estos factores son como la nutrición, utilización de suplementos, gestión de estiércol, etc. Este estudio se realizó en la Universidad Politécnica de Valencia, constó de dos fases, primero una fase de campo que se realizó en la granja de cabras de la Universidad, y la otra una fase de laboratorio que fue realizada en el Laboratorio del Departamento de Ciencia Animal de la misma Universidad. Este experimento se realizó con 10 cabras de raza Murciano-Granadina con pesos comprendidos entre 44,1 ± 4,47 Kg de peso vivo. El objetivo de este estudio fue probar dos tipos de forraje (uno convencional como es la alfalfa y el otro un residuo de la poda de los limoneros; hoja de limón), y ver cómo estas dietas afectaban en los parámetros de producción de leche y ácidos grasos, balance de carbono y nitrógeno, producción de GEI. A estos animales se los separó en dos grupos para analizar los dos tratamientos de este estudio; el T1(pellet de Alfalfa + pienso comercial) y el T2 (pellet de Limón + pienso comercial). Los resultados mostraron diferencias significativas (P < 0,05) en el nitrógeno retenido siendo mayor en el T1, al igual que mayor producción de carbono proveniente del CO2 y CH4 de la respiración. En cuanto a producción de leche la proteína es mayor en el T1 y la lactosa en T2; mientras que en la producción de GEI fue mayor el metano tanto proveniente de la fermentación entérica como la gestión de estiér

[ES] El objetivo de este trabajo fue estudiar los efectos de la sustitución de grano de cebada en la dieta por pulpa de naranja o vainas de soja en el balance de nitrógeno y carbono, las emisiones de metano y el rendimiento de la producción de leche en cabras. Para ello, se seleccionaron doce cabras lecheras Murciano-Granadina y se dividieron en tres grupos basados en un peso corporal similar (42,1 ± 1,2 kg) y la producción de leche (2,16 ± 0,06 kg/cabra/día). El experimento se realizó en un diseño cruzado donde un grupo de cuatro cabras fue alimentado con una ración mixta de grano de cebada, en otro grupo de cuatro cabras se reemplazó el grano de cebada por pulpa de naranja y el último grupo de cuatro cabras se alimentó con soja. Después de la adaptación a las dietas, las cabras se establecieron en jaulas individuales y se analizaron las heces, la orina y la leche. Asimismo, las mediciones de intercambio gaseoso fueron registradas por un sistema móvil de calorimetría en circuito abierto. El consumo de materia seca fue similar en los tres grupos (2,03 kg/d, en promedio). No se observó ninguna influencia de la dieta en el balance energético. Las dietas basadas en pulpa de naranja y cascarilla de soja mostraron una mayor movilización de grasa que en el caso de grano de cebada. El ácido pentadecanoico y el ácido heptadecanoico fueron potenciales biomarcadores de la función del rumen debido a los contenidos más elevados encontrados en la leche de cabras con la dieta de pulpa de naranja y vainas de soja frente al detectado en las cabras con dieta de grano de cebada, lo que sugiere un impacto de estas dietas sobre el metabolismo bacteriano rumen. Esto probablemente esté relacionado con un suministro de nitrógeno inferior en el caso de la dieta de pulpa de naranja para sintetizar proteína microbiana y un mayor contenido de grasa en el caso de la dieta de cascarilla de soja. La sustitución de grano de cereal con subproductos fibrosos no aumentó las emisiones de metano (54,7, [EN] The aim of this experiment was to study the effects of substituting dietary barley grain with orange pulp or soybean hulls on energy, nitrogen and carbon balance, methane emission and milk performance in dairy goats. Twelve Murciano-Granadina dairy goats in midlactation were selected and divided into three groups based on similar body weight (42.1 +/- 1.2 kg) and milk yield (2.16 +/- 0.060 kg/goat/day). The experiment was conducted in an incomplete crossover design where one group of four goats was fed a mixed ration of barley grain (BRL), another group of four goats replaced barley grain with orange pulp (OP) and the last group of four goats with soybean hulls (SH). After adaptation to diets, the goats were allocated to individual metabolism cages and intake, faeces, urine and milk were recorded and analysed. Then, gas exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. Dry matter intake was similar for all three groups (2.03 kg/d, on average). No influence of the diet was observed for energy balance and the efficiency of use of metabolizable energy for milk production was 0.61. The OP and SH diets showed greater (P < 0.05) fat mobilization (-42.8 kJ/kg of BW0.75, on average) than BRL (19.2 kJ/kg of BW0.75). Pentadecanoic acid (15: 0) and heptadecanoic acid (17: 0) were potential biomarkers of rumen function because the higher contents found in the milk of OP and SH goats than BRL suggest a negative impact of these diets on rumen bacterial metabolism; probably linked to the lower nitrogen supply of diet OP to synthesize microbial protein and greater content of fat in diet SH. Replacement of cereal grain with fibrous by-products did not increased enteric methane emissions (54.7 L/goat per day, on average). Therefore, lactating goats could utilize dry orange pulp and soybean hulls diets with no detrimental effect on milk performance.

Tesis por compendio, [EN] For many years energy needs of ruminants have tried to be known to formulate rations adjusted, but it has been found that there are a variety of factors that affect them. Therefore, lots of studies are needed for evaluating the effect of these factors. Consequently, the main objective of this Thesis was to design and validate a respirometry system based on indirect calorimetry, which would allow assessing energy needs of small ruminants accurately. It was intended from the beginning it was a mobile system and of relatively low cost. Furthermore, a methane gas analyzer was incorporated to this system, which allowed the measurement of emissions of this greenhouse gas and quantification of energy losses in the form of methane. Initially the system had connected a mask, which was placed on the animal's face. A sample of exhaled gas was stored in a gas collection bag which was connected to the analyzer, and it measured the concentration of O2, CO2 and CH4 from the air. The proper functioning of the system was checked by a pilot experiment with dry Murciano-Granadina breed goats fed at maintenance level. Later this system was improved. Some of the most important changes were the replacement of the mask by a head hood in which the animal introduced the whole head, and the development of software that recorded and kept automatically concentrations of O2, CO2 and CH4 in exhaled air. This improvement allowed gas measurements during longer periods of time and recording more data. These changes were also validated through a pilot test with dry Manchega breed sheep. Subsequently, three experiments were performed. One of them with dry Guirra ewes and the other two with Murciano-Granadina goats during mid lactation. Diets were mixed rations that differed in the inclusion of cereal or fibrous by-products. In these experiments the effect of diet was studied on digestibility, energy balance and carbon-nitrogen, oxidation of nutrients, rumen parameters and methane production; in, [ES] Desde hace años se ha tratado de conocer las necesidades energéticas de los rumiantes con el fin de formular raciones ajustadas, pero se ha comprobado que hay una gran variedad de factores que les afectan; por ello son necesarios estudios que evalúen el efecto de estos factores. Como consecuencia, el principal objetivo de esta tesis fue diseñar y validar un equipo de respirometría, basado en calorimetría indirecta, que permitiese evaluar las necesidades en energía de pequeños rumiantes de forma precisa. Se pretendió desde el inicio que fuese un sistema móvil y de relativo bajo coste. Además, a este sistema también se le incorporó un analizador de gas metano, que permitía la medición de las emisiones de este gas de efecto invernadero y la cuantificación de las pérdidas energéticas en forma de metano. Inicialmente el equipo tenía conectada una máscara que se colocaba en la cara del animal. Una muestra del gas espirado era almacenada en una bolsa de recogida de gases que era conectada al analizador, el cual medía la concentración de O2, CO2 y CH4 del aire. Se comprobó el correcto funcionamiento del sistema mediante una prueba piloto con cabras de raza Murciano-Granadina secas, alimentadas a nivel de mantenimiento. Posteriormente este sistema fue mejorado. Algunos de los cambios más importantes fueron la sustitución de la máscara por una urna en la que el animal introducía la cabeza entera, y el desarrollo de un software que registraba y guardaba de forma automática las concentraciones de O2, CO2 y CH4 del aire espirado. Esta mejora permitía medidas de gases durante periodos de tiempo más largos y el registro de muchos más datos. Estas modificaciones también fueron validadas mediante una prueba piloto con ovejas de raza Manchega secas. Posteriormente se realizaron tres experimentos. Uno de ellos con ovejas de raza Guirra secas y los otros dos con cabras Murciano-Granadinas en mitad de lactación. Las dietas fueron raciones mixtas que diferían en la inclusión de cere, [CA] Des de fa anys s'ha tractat de conèixer les necessitats energètiques dels remugants a fi de formular racions ajustades, però s'ha comprovat que hi ha una gran varietat de factors que els afecten; per això són necessaris estudis que avaluen l'efecte d'estos factors. Com a conseqüència, el principal objectiu d'aquesta Tesi va ser dissenyar i validar un equip de respirometría, basat en calorimetria indirecta, que permetera avaluar les necessitats en energia de menuts remugants de forma precisa. Es va pretendre des de l'inici que fóra un sistema mòbil i de relatiu baix cost. A més, a este sistema també se li va incorporar un analitzador de gas metà, que permetia el mesurament de les emissions d'este gas d'efecte hivernacle i la quantificació de les pèrdues energètiques en forma de metà. Inicialment l'equip tenia connectada una màscara que es col·locava en la cara de l'animal. Una mostra del gas expirat era emmagatzemada en una bossa d'arreplega de gasos que era connectada a l'analitzador, el qual mesurava la concentració d'O2, CO2 i CH4 de l'aire. Es va comprovar el funcionament correcte del sistema per mitjà d'una prova pilot amb cabres de raça Murciano-Granadina seques, alimentades a nivell de manteniment. Posteriorment este sistema va ser millorat. Alguns dels canvis més importants van ser la substitució de la màscara per una urna en què l'animal introduïa el cap sencera, i el desenrotllament d'un programari que registrava i guardava de forma automàtica les concentracions d'O2, CO2 i CH4 de l'aire expirat. Esta millora permetia mesures de gasos durant períodes de temps més llargs i el registre de moltes més dades. Estes modificacions també van ser validades per mitjà d'una prova pilot amb ovelles de raça Manxega seques. Després es van realitzar tres experiments. Un d'ells amb ovelles de raça Guirra seques i els altres dos amb cabres Murciano-Granadinas en mitat de lactació. Les dietes van ser racions mixtes que diferien en la inclusió de cereal o subproductes fi

Tesis por compendio, [EN] The main objective of this Thesis was to study the energy metabolism in small ruminants under different nutrition sceneries. As methodology we utilized indirect calorimetry instead of direct calorimetry or feeding trials. Within indirect calorimetry we worked with a portable open circuit gas exchange system with a head hood. This open circuit respiration system permitted completed the whole energy balance and evaluate the efficiency of utilization of the energy of the diet for different physiological circumstances as milk production in dairy goats or maintenance in sheep. Besides, we could quantify in each trial some of the wastes related to environmental pollution as CH4 emissions and excretion of nitrogen in feces and urine. In this thesis three experiments were designed, two in dairy goats and other in sheep as we described below. In the first experiment, digestibility, energy balance, carbon and nitrogen balance, milk performance, rumen parameters and milk fatty acids and metabolites were obtained. Metabolic cages and open circuit indirect calorimetry system were the methods applied. Treatments consist in two mixed diets with alfalfa as forage. Within the concentrate, oat grain was replaced with rice bran. No significant differences were found for metabolizable energy intake (MEI), 1254kJ/kg of BW0.75 on average, and heat production (HP); 640 kJ/kg of BW0.75 on average. No differences were obtained for milk production (2.2 kg/d on average) and milk fat was greater in the rice bran diet (6.9% vs. 5.3% for rice bran and oat diets, respectively). Energy balance was positive and milk metabolites correlated these found. Regards to CH4 emissions, determined in vivo by gas exchange indirect calorimetry, goats fed the rice bran significantly reduced methane production (23.2 g/d vs 30.1 g/d). In the second experiment, we also used two types of diets, but in this case we substituted the forage and maintained the same concentrate; in one of the diets a grass (Maralfaf, [ES] El objetivo principal de esta tesis fue estudiar el metabolismo energético en pequeños rumiantes bajo diferentes escenarios de nutrición. Como metodología se utilizó la calorimetría indirecta en vez de calorimetría directa o pruebas de alimentación. Dentro de la calorimetría indirecta trabajamos con un sistema portátil de circuito abierto de intercambio de gases con una "urna" (Heat hood). Este sistema de circuito abierto de respiración nos permitió completar todo el balance energético y evaluar la eficiencia de la utilización de la energía de la dieta para diferentes estados fisiológicos como producción de leche en cabras u oveja en mantenimiento. Además fue posible cuantificar en cada ensayo algunas perdidas relacionadas con la contaminación ambiental como emisiones de CH4 y la excreción de nitrógeno en heces y orina. En esta tesis se diseñaron tres experimentos, dos en cabras en lactación y otro en ovejas como describimos a continuación. En el primer experimento se han determinado, digestibilidad, balance energético, balance carbono nitrógeno, producción de leche, parámetros ruminales, ácidos grasos y metabolitos en leche. Jaulas metabólicas y un sistema de circuito abierto de calorimetría indirecta fue el método aplicado. Los tratamientos consistieron en dos dietas mixtas con alfalfa como forraje y dentro del concentrado el grano de avena fue reemplazado por cilindro de arroz. No se encontraron diferencias significativas en la energía metabolizable ingerida (MEI) de 1254 kJ/kg PV0.75 en promedio y una producción de calor (HP) de 640 kJ/kg PV0.75 en promedio. La producción de leche no presentó diferencias significativas entre las dos dietas, (2,2 kg/den promedio), la grasa de la leche fue mayor en la dieta de cilindro de arroz (6,9% vs. 5,3% para cilindro de arroz y avena respectivamente). El balance energético fue positivo y correlacionado a los metabolitos en leche determinados. En cuanto a las emisiones de CH4, determinadas en vivo mediante el intercambio, [CA] El principal objectiu d'aquesta tesi va ser estudiar el metabolism energètic en xicotets ruminants baix diferents escenaris de nutrició. Com a metodologia es va utilitzar la calorimetria indirecta en compte de calorimetria directa o proves d'alimentació. Dins de la calorimetria indirecta treballarem amb un sistema portatil de circuit obert d'intercanvi de gasos amb "urna" (Heat hood). Aquest sistema de respiració de circuit obert ens va permetre completar tot el balanç energètic i avaluar l'eficiència de la utilització de l'energia de la dieta per a diferents circumstàncies fisiològiques com produccion de llet en cabres o manteniment en ovelles. A més va ser possible quantificar en cada assaig algunes perdues relacionades amb la contaminacion ambiental com a emissions de CH4 i l'excreció de nitrogen en femta i orina. En aquesta tesi es van dissenyar tres experiments, dos en cabres en lactación i un altre en ovelles com vam descriure a continuació. En el primer experiment s'han determinat,digestibilidad, balanç energètic, balanç carboni nitrogen, producció de llet, paràmetres ruminales, àcids grassos i metabòlits en llet. Gàbies metabòliques i un sistema de circuit obert de calorimetria indirecta va ser el mètode aplicat. Els tractaments van consistir en dues dietes mixtes amb alfals com a farratge i dins del concentrat el gra de civada va ser reemplaçat per cilindre d'arròs. No es van trobar diferències significatives en l'energia metabolizable ingerida (MEI) de 1254 kJ/kg PV0.75 en mitjana i una producció de calor (HP) de 640 kJ/kg PV0.75 en mitjana. La producció de llet no va presentar diferències significatives entre les dues dietes, (2.2 kg/donen mitjana), el greix de la llet va ser major en la dieta de cilindre d'arròs (6.9% vs. 5.3% per a cilindre d'arròs i civada respectivament). El balanç energètic va ser positiu i correlacionat als metabòlits en llet determinats. Quant a les emissions de CH4, determinades en viu mitjançant l'intercanvi de gasos per cal

Tesis por compendio, [EN] Climate change, a resultant effect of greenhouse gas emissions, is a worldwide concern because its continuation is having significant impacts on people, natural resources and economic conditions around the world. The root cause of this recent past and projected climate change is now recognised to be the warming potential of a number of greenhouse gases that, by absorbing terrestrial infrared radiation, raise the temperature of the troposphere and with it, global surface temperatures. The major greenhouse gases are water vapour, carbon dioxide, methane, nitrous oxide and fluorinated gases. While carbon dioxide receives the most attention as a factor which causes global warming, methane also cause significant radiative forcing. Methane is only second to carbon dioxide in its contribution to global warming and its emissions are caused by both natural and anthropogenic actions. Human activities such as intensive livestock farming are the primary cause of the increased methane concentrations in the atmosphere, being ruminants the animals which create large amounts of methane via fermentation of feeds in the rumen. During this physiological digestive process, hydrogen is released by some microbes during fermentation of forage and is used by methanogenic Archaea (methanogens) to convert carbon dioxide to methane, which is released through eructation, normal respiration and small quantities as flatus. Rumen fermentation of cattle contributes the most towards the greenhouse effect through methane emission followed by sheep, goats and buffalos, respectively. Several techniques have been developed to quantify methane emissions from ruminants - indirect calorimetry, sulphur hexafluoride tracer technique and in vitro gas production technique - and some strategies for reduction of methane emissions from the rumen have been described - defaunation treatment, vaccine and dietary composition -. The initial topics of this research were: design the experiments with goats because, [ES] El cambio climático es una preocupación de ámbito mundial debido a que su perpetuación en el tiempo está teniendo un impacto significativo sobre las personas, los recursos naturales y las condiciones económicas de todo el mundo. La causa fundamental de este fenómeno es el potencial de calentamiento de una serie de gases de efecto invernadero que, mediante la absorción de la radiación infrarroja terrestre, elevan la temperatura de la troposfera y, con ella, las temperaturas superficiales de la Tierra. Los principales gases de efecto invernadero son el vapor de agua, el dióxido de carbono, el metano, el óxido nitroso y los gases fluorados. El metano, después del dióxido de carbono, es el gas que más repercusión tiene sobre el calentamiento global y sus emisiones son causadas tanto por acciones naturales como humanas. Actividades antropogénicas tales como la ganadería intensiva son la principal causa de aumento de las concentraciones de metano en la atmósfera, siendo los rumiantes los animales que mayores cantidades de metano generan a través de la fermentación de alimentos que se produce en el rumen. Las emisiones de metano del ganado vacuno son las que principalmente contribuyen al efecto invernadero seguido de las ovejas, las cabras y los búfalos, respectivamente. Se han descrito diferentes técnicas para medir las emisiones de metano de los rumiantes - la calorimetría indirecta, la técnica del marcador con hexafluoruro de azufre y la técnica de producción de gas in vitro - y, además, se han mencionado algunas estrategias para reducir las emisiones de metano - la defaunación, las vacunas y la composición de la dieta -. Los puntos clave de esta Tesis fueron: diseñar los experimentos con cabras, debido a que no hay muchas investigaciones sobre emisiones de metano en estos animales; estudiar la influencia de la composición de la dieta (hidratos de carbono) como una posible estrategia para la reducción de las emisiones de metano del rumen; y utilizar la calorimetría, [CA] El canvi climàtic és una preocupació d'àmbit mundial ja que la seua perpetuació en el temps està tenint un impacte significatiu sobre les persones, els recursos naturals i les condicions econòmiques de tot el món. La causa fonamental d'aquest fenòmen és el potencial d'escalfament d'una sèrie de gasos d'efecte hivernacle que, mitjançant l'absorció de la radiació infraroja terrestre, eleven la temperatura de la troposfera i, amb ella, les temperatures superficials de la Terra. Els principals gasos d'efecte hivernacle són el vapor d'aigua, el diòxid de carboni, el metà, l'òxid nitrós i els gasos fluorats. El metà, després del diòxid de carboni, és el gas que més repercussió té sobre l'escalfament global i les seues emissions són causades tant per accions naturals com humanes. Activitats antropogèniques com ara la ramaderia intensiva són la principal causa d'augment de les concentracions de metà a l'atmosfera, sent els remugants els animals que més quantitats de metà generen a través de la fermentació d'aliments que es produeix al rumen. Les emissions de metà dels bovins són les que principalment contribueixen a l'efecte hivernacle seguit de les ovelles, les cabres i els búfals, respectivament. S'han descrit diferents tècniques per mesurar les emissions de metà dels remugants - la calorimetria indirecta, la tècnica del marcador amb hexafluorur de sofre i la tècnica de producció de gas in vitro - i, a més, s'han esmentat algunes estratègies per reduir les emissions de metà - la defaunació, les vacunes i la composició de la dieta -. Els punts clau d'aquesta Tesi van ser: dissenyar els experiments amb cabres, pel fet que no hi ha moltes investigacions sobre emissions de metà en aquests animals; estudiar la influència de la composició de la dieta (hidrats de carboni) com una possible estratègia per a la reducció de les emissions de metà del rumen; i utilitzar la calorimetria indirecta com a mètode per quantificar la producció de metà. Es van realitzar tres experiments.

[EN] The objective of this experiment was to study the effects of substituting alfalfa (Medicago sativa) with maralfalfa (Pennisetum sp.) on energy, nitrogen and carbon balance, methane emission, and milk performance in dairy goats. Ten Murciano-Granadina dairy goats in late lactation (45.7 ± 2.96 kg of body weight[BW]) were selected in a 2-treatment and crossover design experiment where each goat received both treatments in 2 periods. One group of five goats was fed a mixed ration with alfalfa as forage (A diet) and the other diet replaced alfalfa with maralfalfa (M diet) in a forage concentrate ratio of 40/60. Diets were isoenergetic and isoproteic. The goats were allocated to individual metabolism cages. After 17 d of adaptation, feed intake, total faecal and urine output and milk yield were recorded daily over a 5 d period. Then, gas exchange measurements were recorded individually by a mobile open-circuit indirect calorimetry system using a head box. Daily dry matter intake was higher on A than on M diets (1.8 vs. 1.6, for A and M respectively), but no differences was observed in metabolizable energy intake (1089 kJ/kg of BW0.75, on average). Greater values in M than A were found in rumen propionic acid (17.5 vs. 15.6 mol/100 mol, respectively) and milk C15:0 (0.81 vs. 0.62 g/100 g), C17:0 (0.33 vs. 0.24 g/100 g) fatty acids, indicating predominance of amylolytic fermentation. Milk uric acid, a potential biomarker of rumen nitrogen flow and feed efficiency, was higher in A than M (133 vs. 102 mol/L). Higher milk yield (1.8 vs. 1.7 kg/d) and CH4 emissions (28.5 vs. 25.9 g/d) in A compared to M diet were observed, respectively. Use of tropical grasses such as maralfalfa in temperate climates could be a strategy for farmers to incorporate forage into feed for flocks, as milk chemical composition did not change markedly and maralfalfa inclusion reduced CH4 emissions by goats (although this reduction did not occur in CH4 emission compared to dry matter intake and mi

Table 2 contained an incorrect footnote. The correct version is supplied at: http://dx.doi.org/10.1017/S0021859615000556, [EN] Improvements of a home-made mobile open-circuit respirometry system for the rapid determination of methane (CH4) and carbon dioxide (CO2) production, oxygen (O-2) consumption and, thereafter, heat production (HP) for small ruminants are described and validated. Upgrades consisted of three main features: utilization of a head hood (replacing the previous face mask); use of a computerized control system, data acquisition and recording for gases and air flux (replacing collecting bags for air sampling); and use of a gas cooler to remove the air sample moisture (replacing the chemical drier (silica gel) approach). Calibration factors were established by injecting nitrogen (N-2) and CO2 in the system into the head hood. Repetitive and consistent values for the calibration factor were obtained for O-2 and CO2 which confirmed the absence of leaks and the good performance of the system. In addition, an experimental test with 12 Manchega female dry sheep was conducted to validate the system. Three diets based on cereal grain, fibrous by-products and alfalfa hay (ALH) were used with four sheep per diet. Metabolizable energy intake was close to metabolizable energy for maintenance. Average HP measured by indirect calorimetry (respiratory quotient (RQ) method) was close to the average HP determined from Carbon-Nitrogen balance (CN method) accounting for 443 and 426 kJ/kg(075) body weight (BW) per day, respectively. Fasting HP was determined by the RQ method with two sheep from the ALH diet accounting for 269 kJ/kg(075) BW per day. The head hood and computerized control, data acquisition and recording as well as the gas cooler improved the system by reducing the labour input without loss of functionality for measuring gas exchange and energy metabolism in small ruminants

[EN] Feeding systems for dairy ruminants need to ensure high intake of energy to achieve maximum milk production potential. This might be accomplished by raising the dietary concentration of cereal grain. Increasing the concentration of starch in diets can lead to undesirable ruminal fermentation, and to prevent it, the partial replacement of cereal grain with low starch by-product feeds is recommended. The purpose of the present study was to compare the effect of fed two mixed diets to dairy goats differing in the type of carbohydrate (starch vs. easily degradable fiber). Energy and nitrogen balance, short chain fatty acids in rumen liquor and milk performance in dairy goats during mid lactation were determined. Enteric methane (CH4) emissions and CH4 production from manure were determined as well. Ten multiparous Muciano-Granadina goats were assigned to two isoenergetic and isoproteic diets (19.1 MJ/kg dry matter (DM) and 18.1% of CP, DM basis) in a crossover design. One group was fed a mixed ration with 21.9% of starch (HS diet) and the other (LS diet) with 7.0% of starch. HS diet had 36% of barley (as source of starch) and it was replaced with soy hulls and corn gluten feed in LS diet (as potentially digestible fiber). No differences were observed for dry matter intake in both diets (2.05 kg/d, on average). A significant increase of ruminal acetic acid was found for low starch diet (66.4 and 56.6 mol/100 mol for LS and HS diet, respectively). No significant effect was found among diets for enteric CH4 emissions (28.5 g/d, on average). Manure derived maximum potential yield was (Bo) higher in HS diet, with 5.9 L CH4/kg OM vs. 0.28 L CH4/kg OM for LS diet, probably associated with the low ADF digestibility. Differences among diets were found for milk production (2.4 vs. 2.2 kg/d for HS and LS, respectively), and greater milk fat was observed with LS diet compared with HS (6.4% vs. 5.5%, respectively).

[EN] The objective of this study is to compare the partition of heat energy (HE) in two sheep breeds by indirect calorimetry and integral calculus. An experiment was conducted with two Spanish native sheep breeds (dry and non-pregnant) which were fed with pelleted mixed diets above maintenance. Six Guirras and six Manchegas breed sheep were selected (58.8 ± 3.1 and 60.2 ± 3.2 kg body weight, respectively). All sheep were fed with the same concentrate mixed ration (0.300 kg cereal straw as forage and 0.700 kg concentrate) in two meals. Half the daily ration was offered at 800 h and another half at 1600 h. The sheep had free access to water. Sheep were allocated in metabolic cages; energy balance and gas exchange were assessed in each sheep. The statistical analyses included the fixed effect of breed and random effect of sheep. The metabolic energy (ME) for maintenance represented 69% of the total ME intake and the average was 354 kJ per kg of metabolic body weight (kg0.75 BW) on average. The basal metabolism (HeE) was greater (P < 0.05) in Guirra than Manchega breed (270 ± 18 vs. 247 ± 15 kJ/kg0.75 BW and day). As sheep were fed with above maintenance, the retained energy in the body accounted for 22% of the ME intake and 77% of the ME intake was lost as heat. 51% of the MEI was converted to HeE; 5% was lost as physical activity of standing and lying down (HjE), and 13% was associated with the process of feeding and work of digestion and metabolism (HdE). Within HdE, 47% represented the cost of intake and feeding and 54% the cost of digestion and metabolism. No differences in HE partition between breeds were found, although Guirra breed showed less efficiency of energy retention than Manchega breed. Therefore, this study demonstrated a tentative approach of partitioning HE, combining indirect calorimetry and integral calculus

The objective of this experiment was to study the effect of substitution of corn by beet pulp on energy partitioning, substrate oxidation, nitrogen and carbon balance and milk performance in dairy goats during late lactation. Twelve multiparous lactating Murciano-Granadina goats were fed two diets. Six goats were fed a mixed ration with 310 g/kg DM of ground corn (diet CORN) and in the other diet the corn was substituted with 302 g/kg DM of beet pulp (diet BP) in a cross-over design. No significant differences between diets were observed for milk production (1.36 kg/day, on average) and differences were found for milk fat (5.39 and 4.21% for BP and CORN, respectively). The metabolisable energy intake was higher (P < 0.05) in the CORN diet than BP (1320 vs 1044 kJ/kg(0.75) BW, respectively). The difference in methane emissions between treatments was significant (P < 0.05) with values of 92 vs 61 kJ/kg(0.75) BW for BP and CORN, respectively, indicating that greater levels of starch in diet reduce methane production. Replacing corn with BP reduced significantly the energy body fat deposition (300 vs 44 kJ/kg(0.75) BW for CORN and BP diets, respectively). This reduction in energy retention for the BP diet did not compromise milk yield and milk energy output.

[EN] The aim of this study was to assess the effect of substitution of dietary corn grain by dry citrus pulp or soybean hulls on energy and nitrogen partitioning, substrate oxidation, methane emission, and milk performance in dairy goats during midlactation. Twelve multiparous Murciano-Granadina goats of similar body weight (41.7 +/- 2.8 kg) were split in 3 groups in an incomplete crossover design. One group of 4 goats was fed a mixed ration with 605 g/kg of dry matter of corn grain (CRG), another group replaced corn grain with dry citrus pulp (CTP), and the last with soybean hulls (SYH). The goats were allocated to individual metabolism cages. After 14 d of adaptation, feed intake, total fecal and urine output, and milk yield were recorded daily over a 5-d period. Then, gas exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. Dry matter intake was similar for all 3 groups (1.53 kg/d, on average). Total replacement of the concentrate with fibrous by-products increased fiber apparent digestibility. The metabolizable energy intake was significantly greater for diet CRG than SYH (1,193 vs. 1,079 kJ/kg of BW0.75, respectively), CTP showed an intermediate value. The heat production was higher for the fiber diet than starchy diet (908 vs. 843 kJ/kg of BW0.75 for SYH and CRG, respectively). The efficiency of use of metabolizable energy for milk production obtained by regression was 0.59. Goats fed CTP and SYH diets produced similar CH4 emissions (34.8 g/d, on average), significantly higher compared with goats fed the CRG diet (24.7 g/d). Goats of the 3 treatments were in negative energy balance, so the oxidation of fat was greater than for carbohydrates. No significant differences were observed for milk production (1.72 kg/d), and milk fat was significantly greater for a more fibrous diet compared with a starchy diet (6.57 vs. 4.95% in SYH and CRG, respectively)

Essential oils (EO) and short-chain fatty acids have potential antimicrobial activity in broilers. This study aimed to investigate the effect of a specific blend of EO and a combination of this blend of EO with sodium-butyrate on growth performance and Salmonella colonization in broilers. A total of 480 one-day-old male broilers were distributed into 5 treatments (8 pens per treatment and 12 birds per pen) and reared during 42 d in experimental conditions. Dietary treatments consisted of the addition of different doses of EO (0 mg/kg, control; 50 mg/kg, EO50 and 100 mg/kg, EO100) or a combination of EO with 1 g/kg of sodium- butyrate (B; EO50 + B, EOB50 and EO100 + B, EOB100) to a basal diet. All birds were orally infected with 10(8) cfu of Salmonella Enteritidis on d 7 of study. Individual BW and feed intake per pen were measured at arrival and on a weekly basis. The prevalence and enumeration of Salmonella in feces was determined per treatment at 72 h postinfection and on d 23 and 37 of study. At slaughter, cecal content and liver samples from 16 birds per treatment were cultured for Salmonella and cecal pH was measured. No differences were observed on growth performance among treatments. All fecal samples analyzed were positive for Salmonella from d 10 to the end of the rearing period. At slaughter, Salmonella contamination (positive samples) in cecum was lower in birds fed EOB50 compared with the other treatments (P < 0.05), whereas birds fed the control diet showed the highest colonization rates. The pH of the cecal content was not different among treatments. Thus, EO or its combination with sodium-butyrate did not affect growth performance. However, a clear effectiveness of these products was observed in Salmonella control, especially when low doses of EO were combined with sodium-butyrate (EOB50).

The aim of this experiment was to study the effect of substituting barley grain by soy hulls and corn gluten feed blend on energy partitioning, substrate oxidation, carbon and nitrogen balance in sheep. The experiment was conducted in a crossover design with 12 dry and nonpregnant adult Guirra ewes (57.5 +/- 1.9 kg of BW) in each group; and sheep were fed two dairy treatments in two 27 d periods. The ewes were fed with two different mixed diets; one group was fed a mixed diet with 365 g/kg of dry matter (DM) of barley grain (BRL diet) and the other diet (SHGF diet) replaced barley with soy hulls (271 g/kg DM) and gluten feed (93 g/kg DM). Six sheep per group were used to determine apparent total tract digestibility (10 d adaptation plus 5 digestibility and balance of nutrients), gas exchange (12 d), oxidation of nutrients and carbon and nitrogen balance. The average values of metabolisable energy (ME) intake, heat production (HP) and retention of energy (RE) were 498,436 and 62 kJ/kg 0.75 of body weight (BW), respectively, with no differences between diets. The estimated value of ME for maintenance was 391 kJ/kg 0.75 BW. The efficiency of use of ME for maintenance (km) was 0.64 and the nutritive value of the diets was 7.6 MJ of net energy/kg DM, on average. Most of the HP derived from oxidation of fat (0.48) for the fibrous diet, and from oxidation of carbohydrates (0.63) for the starchy diet, with no differences in total tissue energy recovered (67 kJ/kg 0.75 BW). This fibrous by-product was utilised by the ewes with no detrimental effect on energy metabolism and resulted in a similar positive energy balance to that of a traditional cereal based diet. The economic advantages and sustainability of this choice should be evaluated.

The aim of this experiment was to study the effect of substituting corn grain by soy hulls and corn gluten feed blend on energy partitioning, substrate oxidation, and milk performance in dairy goats during mid lactation. Ten multiparous Murciano-Granadina goats in mid lactation were fed 2 isoenergetic and isoproteic diets [19.08 MJ/kg of dry matter (DM) and 18.7% of CP, DM basis] in a crossover design. One group of 5 goats was fed a mixed ration with 373 g of corn grain/kg of DM (CRN diet) and the other diet replaced corn grain with 373 g/kg DM of fibrous by-products [soy hulls and gluten feed (SHGF) diet]: 227 g of soy hulls/kg of DM and 146 g of gluten feed blend/kg DM. Fat was added to the SHGF diet to make it isoenergetic. After 10 d of adaptation, the feed intake, refusal, total fecal and urine output, and milk yield were recorded daily over a 5-d period. Then, gas exchange measurements were recorded by a mobile open-circuit respirometry system using a head box for 10 d. Dry matter intake was similar for both diets (2.07 kg/d, on average). Greater and significant values were found in the SHGF diet for ammonia N, energy in urine, and oxidation of protein. Values were significantly lower for heat production of fermentation, indicating a decrease in rumen fermentation with this diet, probably due to an excess of crude protein in the diet and lack of synchronization of the nonfiber carbohydrates with rumen-degraded protein. The metabolizable energy intake was no different between CRN and SHGF treatments, with an average value of 1,444 kJ/kg of BW0.75. Due to the positive energy balance during mid lactation in this trial, most of the heat production from oxidation of nutrients derived from carbohydrate oxidation (55%, on average), followed by oxidation of fat (29%, on average). No significant differences were observed for milk production, although milk fat was significantly greater for the SHGF diet than the CRN diet (7.0 vs. 5.4%, respectively). Despite the differe

[ES] 10 cabras en lactación con 2 dietas que difieren en el nivel de almidón. Se evaluó la producción de CH4 por intercambio respiratorio. La dieta con un 15% de almidón a penas disminuyó la producción de CH4 (4,06%) frente a la dieta con un 43% (4,61%). Además, presentó un mayor contenido graso en la leche., [EN] 10 lactating goats with 2 diets differing in the level of starch. We evaluated the production of CH4 by respiratory exchange. The diet with 15% of starch decreased slightly CH4 production (4,06%) versus diet with 43% (4,61%); moreover it registered a higher fat content in the milk.

The heat production (HP) from CH4 and CO2 production and O-2 consumption was determined by the respirometry quotient (RQ) method and by C-N balance measurements (CN method). Twelve dry and none pregnant Guirras sheep were fed with 3 diets consisting in the same quantity of alfalfa hay (2 kg/d offered) and increasing quantities of barley grain (150,300 and 450 g/d). The experimental design was completely random with 4 replication by treatment. Fasting HP was determinate in one sheep from each group. Ewes were allocated to individual metabolism cages at thermoneutrality. After 10 d of adaptation, feed intake, and total fecal and urine output were recorded daily for each ewe during a 5 d period, as well as BW at the beginning and end of the period. Gas exchange measurements were recorded by open-circuit face mask respirometry system. Average HP measured by RQ method was in agreement with the average HP determined by CN method accounting for 395.6 and 393.4 kJ/kg(0.75) BW/d, respectively. The metabolizable energy requirement for maintenance (MEm) was estimated by linear regression at 352.3 kJ/kg(0.75) BW. (C) 2012 Elsevier B.V. All rights reserved.

Ruminants may contribute to global warming through the release of methane (CH4) gas by enteric fermentation. Most CH4 emissions from ruminants are estimated using simple regression equations. Thus a mechanistic dynamic model to predict CH4 output by goats was developed by using a computer-aided simulation device via object-oriented modeling. The model was structured into seven stocks; body weight, feed, metabolism, milk, methane and reserves (with two stocks). The goat model was set up to simulate indoor facilities in which the goat was fed a mixed ration. Then, 24 goats were used to evaluate the model during 150 days of lactation. A calorimetry system based on an open circuit respiration mask was used for quantification of respiratory CH4 production, as a way to validate the CH4 simulated. The mathematical simulation model estimated an average CH4 conversion factor (Ym) value of 5.3%, and an average daily CH4 production of 1.55 MJ/d. The average daily CH4 production for the validation group of goats was 1.51 MJ/d. Based on our simulation over 5 months of lactation for a mixed diet, use of the Intergovernmental Panel for Climate Change values (Ym = 6.5) could result in an overestimation of enteric CH4 for dairy goats fed concentrate diets.

8 cabras en lactación con 2 dietas que difieren en el nivel de almidón. Se evaluó la producción de CH4 por intercambio respiratorio. La dieta con un 29,03% de almidón disminuyó la producción de CH4 (60,60 kJ/PV0,75) frente a la dieta con un 14,44% (100,37 kJ/PV0,75). Además, presentó una mayor eficiencia energética y retención de nitrógeno.

Heat production (HP) from CH4 and CO2 production, and O-2 consumption was determined by the respiratory quotient (RQ) method and by the C-N balance (CN method). Twelve dry Manchegas sheep were fed with a diet constituted by alfalfa hay and barley grain at three levels, approximately 1, 1.5 and 2x metabolizable energy for maintenance (MEm). Later, the sheep were fed close to maintenance and HP determined by indirect calorimetry after 3 d fasting. The sheep were allocated to metabolism cages. After 10 d of adaptation, feed intake, and total fecal and urine output were recorded daily during 5 d, as well as the body weight (BW) at the beginning and end of the sampling period. Gas exchange measurements were recorded by a mobile open-circuit respirometry system. Average HP measured by RQ method was in agreement with the HP determined by CN method accounting for 410 and 407 kJ/kg(0.75) BW/d, respectively. Fasting HP was 268 kJ/kg(0.75) BW. Proportion of energy associated to the oxidation of protein (OXP), carbohydrate (OXCHO) and fat (OXF) was calculated. In fasting condition most of HP associated to substrates oxidation (HPx) was due to OXF (0.931) and less to OXP (0.037) and OXCHO (0.032). OXP was increased with the feeding level and was greater (0.193) than in fasting. OXCHO was increased with the feeding level until a stable level (0.507).

A mobile open-circuit respirometry system was constructed for estimating heat production (HP) in small ruminants from CH4 and CO2 production and 02 consumption by the respiratory quotient (RQ) method. The method was evaluated against HP estimates by C-N balance measurements (CN method). Calibration factors were established injecting N-2 into the system. Repetitive and consistent values for the calibration factor were obtained (1.0065 +/- 0.01307, n = 9), which confirms the absence of leaks and good performance of the whole system. A pilot experiment with 14 Granadina female dry goats was conducted to evaluate the system. The metabolizable energy intake (MEI) was close to ME for maintenance. Average HP measured by RQ method was in agreement with the average HP determined by CN method accounting for 505 and 500 kJ/kg(0.75) BW/d. respectively. It is concluded that the mobile system was suitable for measuring gas exchange and energy metabolism in small ruminants.

[ES] Se seleccionaron doce ovejas de dichas razas pertenecientes a la granja experimental de la Universidad Politécnica de Valencia de tres años de edad, secas y no gestantes. Los métodos de calorimetría utilizados fueron el de Coeficiente respiratorio (método CR) y el de balance Carbono-Nitrógeno (método C-N). En los resultados obtenidos se observaron valores similares entre ambos métodos; la Energía Retenida en promedio fue de 185,3 kJ/kg PV0,75 (método CR) y 192,52 kJ/kg PV0,75 (método C-N) y un análisis de correlación entre ambos métodos dio un coeficiente de correlación r = 0,98. La Energía Neta para el mantenimiento calculada como la producción de calor en ayunas con el método de CR fue 317,7 kJ/kg PV0,75 y la Energía Metabolizable para el mantenimiento estimada por regresión fue de 352 kJ/kg PV0.75, [EN] Twelve sheep were selected, sheep that belong to the UPV¿s experimental farm, of three years old, dry and not pregnant. The calorimetry methods used were the Respiratory coefficient (CR method) and the Carbon-Nitrogen balance (CN method). Once the experiment was finished proportionality between both methods was observed as results were similar; the Retained Energy was in average 185.3 kJ/kg BW0.75 (CR method) and 192.52 kJ/kg BW0.75 (CN method), the analysis on the correlation between both methods was r = 0.98. The Net Energy for the maintenance, calculated as fasting heat production with the CR method was 317.7 kJ/kg BW0.75 and the Metabolized Energy for the maintenance estimated by regression was 352 kJ/kg BW0.75.

[Otros] Dans cette étude, 48 brebis en lactation, appartenant à 2 races méditerranéennes, la race Guirra (race autochtone rustique) ou la race Manchega (race mixte) ont été utilisées pour évaluer l¿effet de l¿inclu- sion de fruits d¿agrumes entiers (WCF) dans leurs rations. Quatre rations complètes ont été formulées pour être iso-énergétiques et iso-azotées. Elles se différenciaient par le taux d¿incorporation de WCF (0, 10, 20 et 30%) qui était substitué, sur une base matière sèche, à de l¿orge concassée ou à de la pulpe de betterave en pellets. La production et la composition du lait ont été mesurées une fois par semaine sur deux traites successives (matin et soir). La production de lait obtenue avec le group recevant 30% WCF a été supérieure de 12% à celle des autres groupes. De plus, on a observé une réduction du taux butyrique avec l¿inclusion de WCF. Elle était de 8,2; 7,95; 7,69 and 7,1 pour les groups recevant respectivement 0, 10, 20 et 30% de WCF (P<0,05). La teneur en protéines du lait a été maximale avec le group recevant 10% WCF (6,4%) et minimale avec celui ayant 30%WCF (6,0% ; P<0,05), car la teneur en caséine du lait a été la plus faible avec le groupe recevant 30%WCF (-0,3% par rapport aux groupes avec 0 et 10% de WCF; P< 0,05), tandis que la teneur en protéines solubles a été similaire pour tous les groupes (moyenne: 1,17%). Tout au long de la période expérimentale, on a observé une diminution de la production de lait standard (6%FCM) avec toutes les rations (-35% par semaine), mais il a été plus prononcé pour les groupes recevant 20% et 30% WCF que pour les autres. En conclusion, l¿incorporation de WCF pourrait contribuer à diminuer la dépendance vis à vis des céréales pour les brebis à haute production sans affecter les paramètres de production laitière ; mais d¿autres études relatives aux effets de WCF sur la condition corporelle et sur la capacité des animaux en lac- tation à mobiliser leurs réserves doivent être faites., [EN] A total of 48 lactating ewes, belonging to 2 different Mediterranean breeds Guirra (rustic native breed) and Manchega (mixed aptitude breed) were used to evaluate the effect of the inclusion of whole citrus fruits (WCF) in their rations. Four iso-energetic and iso-protein total mixed rations were formulated containing fresh WCF at 0, 10, 20 and 30% replacing dry-rolled barley and pelleted beet pulp on a DM basis. The milk yield and composition were obtained once a week at morning and afternoon milking. Total milk yield values observed for 30% WCF group were 12% higher than for the others. Also, a reduction of the milk fat content with the inclusion of WCF was observed, being 8.2, 7.95, 7.69 and 7.1% for 0, 10, 20 and 30% WCF groups (P<0.05). Milk protein content was maximum for ewes on 10% WFC ration (6.4%) and minimum for 30% WCF group (6.0%; P<0.05), due to the lower milk casein content of 30% WCF group (-0.3% respect to 0 and 10% WCF groups; P<0.05), while soluble protein content was similar for all the groups (mean: 1.17%). Throughout the experimental period, a reduction of 6% fat corrected milk (6%FCM) production was observed with all the rations (-35 ml per week), but it was steeper for 20 and 30% WCF groups than for the other 2 groups. In conclusion, WCF could contribute to diminishing dependence of high-milking ewes on grains without affecting the milk output, however further studies related to WCF effect on body condition and on the capacity of lactating animals to mobilize body reserves should be made.