Search

Methane production was individually measured, using open-circuit respiration chambers, in Segureña wethers fed diets including two different levels of olive cake (OC) sprayed with soda solutions to attain 0, 5, 7.5 and 10 g NaOH/100 g OC. Increasing level of OC in diet reduced (P < 0.001) CH production (from 3.34 to 2.37 % of total ingested carbon and from 8.97 to 7.90 % of total digestible energy intake), which represent reductions in energy losses of up to 12 % of the digestible energy (DE) intake. Differences (P ≤ 0.001−0.002) in enteric CH production due to treatment of OC with alkali were observed. The average value for the rate of conversion of feed energy to CH energy (Y) was 5.96 kJ/100 kJ GE intake or 8.97 kJ/100 kJ DE for the standard basal diets, containing 100 g OC/kg diet. Increasing OC in the basal diet to achieve 400 g/kg diet resulted in a substantial reduction of enteric CH production promoting a Y value of 4.18 kJ CH/100 kJ GE or 7.90 kJ CH/100 kJ DE intake. A decrease (P = 0.018) in enteric CH production (l/kg DMI) due to the alkali treatment of OC was noticed. Accurate predictions of CH production were obtained by simple regressions equations relating measured values of CH production and diets composition and/or intake. Dry matter intake and structural carbohydrates content in the diet were accurate predicting factors of the enteric CH production. The best correlations were obtained when enteric CH yield (CH, l/kg DMI) was the variable to be estimated.

Amino acid (AA) composition of body protein is considered constant although there are evidences that AA pattern in pigs may be altered by different factors. Pigs with different body composition and protein deposition rates—like fatty and lean pigs—may differ in AA composition, with possible consequences on their AA requirements. This work investigates effects of genotype and dietary lysine deficiency on AA composition of carcass and muscles of Iberian and Landrace × Large White pigs. Twenty-eight barrows (10 kg body weight [BW]), 14 from each breed, were used. They were randomly assigned to two experimental diets according to a factorial arrangement (two breeds × two diets). Diets were isonitrogenous and isoenergetic (200 ± 1 g CP/kg dry matter (DM); 14.7 ± 0.1 MJ ME/kg DM) and with identical chemical composition except for lysine concentration (10.9 and 5.20 g lysine/kg DM, for lysine-adequate (AL) diet and lysine-deficient (DL) diet respectively). Pigs were individually housed, and daily feed allowance was adjusted on a weekly basis according to BW. Pigs were slaughtered at 25 kg BW. Isoleucine, valine and phenylalanine concentration were higher in carcass protein of Iberian pigs (p <.01). In longissimus muscle, higher concentration of arginine, isoleucine, phenylalanine, lysine and valine (p <.001–p <.05), and lower of methionine (p <.001) were detected in Iberian pigs, whereas phenylalanine, leucine, lysine, threonine and methionine concentration decreased and arginine increased (p <.001–p <.05) when pigs were fed DL diet. Genotype and lysine deficiency effects were moderate in the AA composition of protein of biceps femoris muscle. The results show that AA proportions in protein of carcass and longissimus muscle can be influenced by pig genotype and conditions of lysine shortage. The biceps femoris muscle, with different functional and metabolic properties, shows more constant AA composition than longissimus, which seem to prevail independent from genotype or n

In pig production, factors such as nutritional system and genotype affect quality characteristics of meat. This study was aimed to evaluate differences in nutritional composition and colour of meat between Iberian (IB) and Landrace × Large White (LLW) pigs reared under identical nutrition and management conditions. Nutrient composition, mineral content, fatty acid profile and instrumental colour of two muscles (longissimus thoracis and biceps femoris) were examined at two growing stages (50- and 115-kg weight). Significant differences were found in relation to genotype. IB muscles contained higher amounts of intramuscular fat, dry matter, monounsaturated fatty acids, iron and zinc, and were redder (higher a∗ value) and with less colour saturation (lower hue angle), than those from LLW pigs. Significant relationships between colour coordinates with the mineral content and the lipid profile of muscles were found: redness was mainly linked to iron, zinc and monounsaturated fatty acids levels, whereas yellowness was positively related with copper, polyunsaturated fatty acids and linoleic acid level. The results of the present study support that muscles from the IB pig genotype have special characteristics, which may enhance the overall quality of meat compared with conventional or high-lean porcine breeds, even under identical management system, due to its particular fat composition and colour attributes.

Along this review we describe the results from a series of experiments performed to assess the utilization of dietary protein by the Iberian pig throughout different stages of its productive cycle. Nutritional dose-response studies involving several isoenergetic treatments differing in protein concentration -all with similar amino acid profile following the ideal protein concept- along with comparative growth and metabolic studies with conventional breeds have been performed. Our observations reveal that the capacity of this breed for protein accretion is rather limited compared to that of conventional breeds at similar stages of growth, and suggest the need for reducing the concentration of protein in the diet of the Iberian pig to comply with its metabolic profile. Basic comparative studies have brought to light information to help us explaining some of the metabolic peculiarities of this autochthonous breed of pigs, like the low capacity to accrete protein and lean tissue. We summarise all the information gathered in several experiments and provide recommendations on the concentration and composition of dietary protein in the diet for purebred animals during different phases of growth. Adequate nutritional management, particularly dietary protein provision, improves the efficiency of utilization of dietary protein and results in relevant economic, environmental and animal welfare benefits.

Trace elements (i.e. Fe, Cu and Zn) are essential for maintaining importantphysiological processes, and dietary requirements in pigs should be carefully established. Asa valid approximation to study trace mineral needs, an experiment was conducted to analysethe content of Fe, Cu and Zn in muscles from two porcine genotypes. Sixteen pigs (8 Iberian, IB, and 8 Landrace × Large White, LDW) were used. They were fed isoenergetic diets (14 MJ/Kg DM) containing either 130 or 170 g CP/kg DM, to match protein requirements of each breed (4 pigs/genotype and CP level).The pigs were sacrificed at 115 kg LW, and samples of longissimus dorsiandbiceps femorismuscles were obtained.Fe and Zn concentration in muscles was significantly influenced by genotype, being higher amongIB pigs. Asignificant effect of dietary protein was observed in the IB group, as pigs fed with higher protein levels had lower values of Fe in both muscles. Cu content was not affected by genotype or diet. These results indicate that deposition of trace minerals, such as Fe and Zn, is under genetic control, and support the importance of meat from IB pigs as a good source of Fe and Zn

The main objective of this work was to investigate the effects of feeding Lys-deficient diets on muscle biochemical characteristics, particularly intramuscular fat concentration and fatty acid profile, in a fatty (Iberian) and a conventional pig genotype (Landrace × Large White [LDW]) maintained in identical experimental conditions. Performance and plasma metabolite changes were also monitored. Twenty-eight barrows of 10 kg initial BW, 14 of Iberian and 14 of LDW breed, were randomly assigned to each of 2 experimental diets in a 2 × 2 factorial arrangement (2 breeds × 2 diets). Seven pigs were allocated to each treatment combination. Diets (isonitrogenous and isoenergetic; 200 g CP/kg DM and 14.7 MJ ME) based on barley, corn, corn gluten meal, and soybean meal, with identical composition, except for their Lys content (10.9 g/kg for the diet adequate in Lys and 5.2 g/kg for the diet deficient in Lys), were assayed. Pigs were housed in individual 2 m pens and fed at 85% of ad libitum intake of the Iberian genotype, of greater intake capacity. Daily feed allowance was based on BW individually measured each week. At 25 kg BW, pigs were slaughtered by exsanguination after electrical stun- ning. Blood samples were taken and longissimus dorsi and biceps femoris muscles were rapidly dissected and stored frozen prior to analysis. Performance was reduced in both pig breeds when fed Lys-deficient diets, particularly in LDW pigs (breed × diet interaction, P < 0.05). Intramuscular fat content increased in longissimus dorsi of Iberian (P < 0.05) and in biceps femoris of both pig genotypes (P < 0.01) when fed Lys-deficient diets. Oleic acid increased (P < 0.05) and PUFA acid decreased (P < 0.01) in longissiumus dorsi and biceps femoris of pigs of both genotypes fed Lys-deficient diets. The proportion of oxidative fibers (P < 0.001) and free l-carnitine content (P < 0.05) increased in longissimus dorsi of both pigs types fed Lys-deficient diets. Plasma creatinine was greater in LDW

Thirty entire male Iberian (IB) pigs of 12 kg initial BW were used to study the effects of dietary protein-to-energy ratio on performance, body protein accretion, and tissue composition. Two nutritional regimes were supplied at 3 stages of growth (Phase I, from 12 to 30 kg BW; Phase II, from 30 to 45 kg BW; and Phase III, from 45 to 100 kg BW): the first regime (RefP/E) was formulated to provide optimum protein-to-energy ratios for castrated IB pigs at several stages of growth from 10 to 100 kg BW; the second (IncP/E), for which an overall increase of 2.5 g digestible protein/MJ ME was provided, would allow an increased potential for lean tissue growth presumably well above that expected for the entire male of an obese pig breed. The pigs were surgically castrated at 45 kg BW and slaughtered at about 100 kg BW. In Phases I and II, in which feed was provided ad libitum, no significant differences between dietary treatments in ADG (580 ± 10 and 740 ± 11 g, on average, respectively), G:F (0.475 ± 0.004 and 0.362 ± 0.005, on average, respectively), and gain:ME intake ratio (37.8 ± 0.4 and 26.1 ± 0.4 g/MJ, on average, respectively) were found (P > 0.05). After surgical castration, for the entire fattening period (Phase III), ADFI was fixed and highly restricted. A lower gain:ME intake ratio (14.0 vs. 15.1 g/MJ; P < 0.01) was obtained when the diet with the highest digestible protein:ME ratio was offered (IncP/E). With this regime, body protein accretion significantly improved in the IB boar growing from 12 to 45 kg BW, irrespective of the stage of growth, although the amount of protein accreted was notably enhanced at the later stage (75 vs. 85 g/d in Phase I [P < 0.05] and 110.5 vs. 151 g/d in Phase II [P < 0.001]). However, the efficiency of utilization of dietary N remained unchanged irrespective of the diet fed (P > 0.05). In contrast, in the fattening stage, similar daily rates of N retention (P > 0.05) were found, in spite of the observed differences in digestible

The objective of the present work wasto investigate the effect of dietary Lys deficiency upon intramuscular fat (IMF) concentrationand its fatty acid profile in an obese (Iberian, IB) and aconventional pig genotype (LDW). We used 28 castrated male pigsof 10 kg of initial BW, 14 from each type. Pigs were fed two diets, based on barley, maize, gluten meal and soybean meal, with identical composition,except for their Lys content (0.98% Lys, diet AL, adequate in Lys; and0.47% Lys, diet DL, deficient in Lys). The rest of nutrients met or exceeded recommendations. Seven pigs from each type were fed one of the dietsat 85% of ad libitumof the Iberian pigs. At 25 kg BW pigs were slaughtered and L. dorsiand B. femorismusclessampled.Performance was reduced in both pig types fed LD diets, particularly LDW pigs (P<0.05).Pigs fed LD diets showed higher IMF contentand oleic acid proportion,and lowerrelative percentage of poliinsaturated fatty acids. Feeding Lys deficient diets canbe a suitable strategy for increasing meat quality,both in obese and lean pig types,although further research is needed to deep our knowledge on the mechanism involved in thesechanges

© 2014 Ministerio de Agricultura Pesca y Alimentacion. All Rights Reserved. A meta-analysis was made of data from a total of 211 growing-finishing Iberian (IB) pigs from four separate and independent sets of trials. Within each set of trials, a factorial arrangement of treatments was used, involving several concentrations of ideal protein in the diets and two or three levels of feed intake. Pigs were slaughtered at several stages of growth from 10 to 150 kg body weight (BW). The partition of dietary protein in the body of the pigs, the empty-body gain (EBG), the chemical composition of EBG, growth of primal cuts in the cold eviscerated carcass (without head, feet, and tail), and mass of dissected tissues in trimmed shoulder and ham were determined. Linear regression equations allowed estimating N requirements for maintenance as 175 mg/(kg BW0.75 · kg dry-matter intake) · d–1 and an average value for the net efficiency of utilization of the dietary protein apparently absorbed of 0.386. In pigs offered adequate protein to energy diets, EBG was predicted as a function of average BW and feeding level (p < 0.001). Multiple regression equations were constructed, which derived nutrient (g kg–1) or energy (MJ kg–1) composition of EBG as a function of empty-body weight (EBW), dietary protein to energy ratio, and level of feeding (p < 0.001). These predictive equations, not applicable to pigs of lean and conventional genotypes, can contribute to the design of optimal feeding strategies to improve the efficiency of IB pig production systems and to achieve high quality standards in end products for the market.

Ninety purebred Iberian (IB) sows in second or third parity were used to determine the effects of dietary lysine (Lys) concentration during last third of pregnancy on sow and litter performance. The sows were randomly assigned to one of three dietary treatments: 5.5 (LLys, Control), 7.4 (MLys) and 8.7 (HLys) g Lys kg-1 diet. Feed allowance was 2.30-2.33 kg d-1. Close to farrowing a conventional lactation diet was used. Dietary Lys did not affect body-weight (BW) gain in late gestation of second-parity sows. However, in third-parity sows, a strong tendency was observed for BW gain to increase during late pregnancy with dietary Lys levels higher than 5.5 g kg-1 (p=0.061). Body-weight losses during lactation were never influenced by Lys supply. A strong tendency (p=0.064) for a lower ratio between piglets born alive and total piglets born was observed in second-parity sows fed the Control gestation diet. Litters and piglets from sows on this diet had the lowest weight at birth (p0.05). In conclusion, under moderate energy supply, adequate reserves for subsequent lactation can be achieved in second- and third-parity IB sows with a daily provision of at least 17.2 g lysine over the last third of pregnancy, what implies a substantial increase in protein supply respect to traditional practices.

Ninety purebred Iberian (IB) sows in second or third parity were used to determine the effects of dietary lysine (Lys) concentration during last third of pregnancy on sow and litter performance. The sows were randomly assigned to one of three dietary treatments: 5.5 (LLys, Control), 7.4 (MLys) and 8.7 (HLys) g Lys kg-1 diet. Feed allowance was 2.30-2.33 kg d-1. Close to farrowing a conventional lactation diet was used. Dietary Lys did not affect body-weight (BW) gain in late gestation of second-parity sows. However, in third-parity sows, a strong tendency was observed for BW gain to increase during late pregnancy with dietary Lys levels higher than 5.5 g kg-1 (p=0.061). Body-weight losses during lactation were never influenced by Lys supply. A strong tendency (p=0.064) for a lower ratio between piglets born alive and total piglets born was observed in second-parity sows fed the Control gestation diet. Litters and piglets from sows on this diet had the lowest weight at birth (p0.05). In conclusion, under moderate energy supply, adequate reserves for subsequent lactation can be achieved in second- and third-parity IB sows with a daily provision of at least 17.2 g lysine over the last third of pregnancy, what implies a substantial increase in protein supply respect to traditional practices.

Little information is available concerning mineral metabolism in suckling piglets. The utilization of milk minerals and the mineral composition of Iberian (IB) suckling piglets were studied in two consecutive experiments at different ambient temperatures (trial 1, 27 ± 2°C; trial 2, 22 ± 2°C). Milk composition and the piglets' performance were determined weekly over a 34 days lactation period and, at the end, body mineral contents were analyzed and mineral retention and bioavailability were calculated. The ash content in IB sows' milk and in suckling IB piglets was found to be higher than that reported for lean genotypes. During lactation, mean ash content per unit of body weight gain in IB piglets (40.6 g kg-1) was 42% higher than that observed for lean breeds, and weaned IB piglets contained 60% more Ca (11-12.7 g kg-1 empty body weight) and P (7-7.5 g kg-1 empty body weight), compared with conventional pigs. Minerals from milk were retained by the IB piglet with an overall efficiency of 78.3%, 66.3% and 48.7% for Ca, P and Mg, respectively. Significant differences between trials were observed in the mineral fraction composition of the milk, which were reflected in piglet body composition at weaning, presumably due to differences in ambient temperature. Present findings underline genotype differences in mineral composition of sow's milk and suckling piglets and may provide a useful starting point for formulating milk-replacer diets for IB piglets.

[Background]: The effects of pelleting on the extent of the Maillard reaction (MR) and on calcium, magnesium and zinc solubility and absorption were analysed in a conventional pre-starter diet for suckling piglets. Development was tested measuring colour, absorbance (280/420 nm), fluorescence, residual free lysine, furosine, hydroxymethylfurfural (HMF) and furfural contents before and after pelleting. Fluorescence, absorbance and mineral solubility were also measured after in vitro digestion of diets. The effects on mineral absorption were tested using Caco-2 cells., [Results]: MR indexes confirmed the development of the reaction during the pelleting of this particular diet compared with the meal diet. The CIE-Lab colour parameters showed a decrease in luminosity (L*) and progress of the colour to the red zone (a*) in the pelleted diet. A 36% decrease in free lysine content was observed. Significant correlations were observed between fluorescence intensity and furosine levels, HMF and furfural. The pelleting process did not modify calcium and magnesium solubility after in vitro digestion, but soluble zinc increased. The efficiency of calcium and zinc transport across Caco-2 cell monolayers was greater in the pelleted diet., [Conclusions]: Evidence of MR development is shown, resulting in various nutritional consequences. Optimisation of pelleting could result in a better formulation of diets for feedstuffs.

Aditivo alimentario para mejorar la composición corporal de los animales disminuyendo su contenido graso y aumentando el contenido proteico. La presente invención se refiere a un aditivo alimentario que contiene una mezcla de betaína y ácido linoleico conjugado (CLA) en el que la concentración de betaína y CLA se encuentran respectivamente en el rango de 0.025 a 0.5 y de 0.25 a 5.5% (porcentajes expresados en peso) siendo la concentración de betaína preferentemente del 0.5% y la del ácido linoleico conjugado de 1.0%.

Serum hormones and metabolites of lean and obese gilts were determined. Fifteen Iberian and fifteen Landrace gilts, of approximately 20 kg body weight, were fed isoenergetic (13.6 kJ ME/g DM, semisynthetic diets either with equilibrated amino acid profile at two crude protein (CP) levels (12% (0.81% lysine (Lys)) and 16% CP (1.08% Lys) as-fed basis) or lysine deficient (12% (0.30% Lys) or 16% CP (0.36% Lys) as-fed basis for Iberian and Landrace, respectively). Lysine deficient diets were offered only at the optimal protein level for maximum protein accretion for each breed. Each dietary treatment was assayed in 5 animals. Gilts were allocated in metabolic cages at 21 ± 1.5 °C with free access to water and fed four times daily at 90% ad libitum during 10 days. On day 11th blood samples were taken 5–5.5 h postprandial and serum obtained and frozen at − 20 °C. Growth hormone (GH), insulin like growth factor I (IGF-1), insulin, leptin, glucose, urea, creatinine, cholesterol and triglycerides were determined. Landrace gilts had higher serum glucose (P < 0.05) and creatinine (P < 0.001) than Iberian while no differences (P = 0.122–0.494) were found for the rest of the biochemical variables. Higher serum levels of insulin, IGF-1 and leptin (60, P < 0.05; 79, P < 0.05 and 189%, P < 0.001, respectively) and no differences in GH (P = 0.512) were encountered in Iberian gilts compared to Landrace. Dietary crude protein did not alter the serum hormonal profile (P = 0.110–0.454). Serum cholesterol (total, P < 0.01; HDL, P < 0.05; LDL, P < 0.05) decreased and triglycerides and urea increased (P < 0.05 and P < 0.001, respectively) as dietary crude protein increased. When lysine deficient diets were used, serum glucose decreased (P < 0.05) and urea increased (P < 0.001) compared to equilibrated diets. Serum insulin (P = 0.052), IGF-1 (P < 0.05) and leptin (P = 0.051) concentration decreased when lysine deficient diets were fed to the animals while GH remained unaffected (P = 0.214).

Contribución al estudio de suelos desarrollados sobre roca caliza, por A. Hoyos de Castro, A. Mª Moreno García y J. González Parra.-- Génesis y evolución de un suelo desarrollado sobre material calizo (Sierra deAralar), por A. Hoyo, A. M. Moreno y J. González Parra.-- Características del humus a lo largo de una toposecuencia de andoso es en la lsla de Tenerife, por A. Polo, C. Gª Milla y F. Velasco.-- Relationship between organic carbon, nitrogen, phoophorus, sulphur and organic matter in some soils of Rajasthau, por L. L. Somani and S. N. Saxena.-- Meteorización experimental de sedimentos aluviales ácidos del valle del Guadalquivir, por Juan de Olmedo Pujoly Angelines Hernández.-- Predicting cation exchange capacity of soils from relative amount of clay and organic matter content, por L. L. Souzani.-- Influencia de la época de siembra de Triticum vulgare L. y grado de infección de Avena sterilis L. en la competencia de ambas especies, por R.González Ponce y V. Hernando Fernandez.-- Estudio de la capacidad competitiva de Avena sterilis L. contra Triticum vulgare L. en comparación a la de este ultimo consigo mismo, por R. González Ponce y V. H ernando Fernández.-- Estudio previo sobre la nutrición del Aguacate por análisis foliar, por S. Jaime Palacios, A. Aguilar Villalvilla y E. Esteban Velasco.-- Influencia del clururo sódico sobre la germinación de semillas de pimiemo (Capsicum annuum), por N. Caro, F. G. Fernández y A. Cerda.-- Aclareo químico de frutos en el olivar manzanillo de Sevilla, por A. Troncoso, I. Prieto y J. Liñan.-- Estudio de un sistema de drenaje a nivel parcelario en pasto Nariño (Colombia), por A. Alvarez López, A. Arias Henández y L. Legarda Burbano.-- Utilización digestiva de dietas con pesticidas, por Ciara Mª Rueda, J. F. Aguilar y J. Boza.—Trabajos recapitulativos.-- Genética de khizobium y de la fijación de nitrógeno, por J. Casadesús y J. Olivares.—Notas previa.-- Aplicaciones de la informática en el reconocimiento y evaluación de suelos

Suelos. Investigación del Departamento de Edafología (1961-1982), por M. L. Palomar García Villamil, J. González Parra, A. M. Moreno García, M. l. Hernando Massanet, J. Hernando Costa, M. C. Fernández Bermejo, J. A. Egido Rodríguez, C. González Huecos y A. López Lafuente.-- Procesos de alteración, génesis y estabilidad mineral de suelos volcánicos, por Sanz, J., Martín de Vidales, J. L., Casas, J. y Guerra Delgado, A.-- Ciclo biogeoquímico de los cationes y humificación, por Francisco Velasco de Pedro.-- Los suelos salinos de San Felipe de Neri, por R. Ortiz Silla y E. Caselles Vegara.--Tipología y erosión de los suelos en un área representativa, por l. Sastre, R. Jiménez, F. D. Pineda y F. G. Bernaldez.-- Silicatos. Longitudes y ángulos de enlace en silicatos, por Enrique Gutiérrez Ríos.-- Retención de dimetoato por bentonitas homoiónicas, por A. García Rodríguez, E. J. López Garzón, J. de D. López González y C. Valenzuela Calahorro.-- Estudio de la cinética de la reacción del oxalato amónico, por A. González Batista, J. García Hernández, J. Hernández Moreno y E. Fernández Caldas.-- Fertilidad de suelos. Efecto de la reacción NH4/ N0-3 sobre el maíz, por Hernando, V., Pardo, M. T. y López-Fando, C. --Extracción química y biológica del hierro, por L. Romero, E. Barahona y A. AguiJar 935 Aplicación de los polinomios ortogonales a fertilización nitrogenada, por Jimeno Martín L.—Nutrición y Fisiología Vegetal.-- Factores nutricionales en la floración y fructificación del olivar, por F. González García y L. Catalina.-- Pretratamientos con diferentes sales de hierro en la germinación de semillas, por María R. de Felipe y A. Vivó.-- Aspectos ecofisiológicos de la producción de grano. 1., por L. F. García del Moral, J. M. Ramos, L. Recalde-Manrique y L. Recalde Martínez.-- Efecto del boro sobre guisante y pimiento, por R. M. Salinas, A., A. Cerdá y F. G. Hernández.-- Estudio de la nutrición del almendro, por José Tomás Soria, Serafín Jaime Palacios y Eduardo Esteban Velasc

Contribución al estudio de suelos desarrollados sobre roca caliza, por A. Hoyos de Castro, A. Mª Moreno García y J. González Parra.-- Génesis y evolución de un suelo desarrollado sobre material calizo (Sierra deAralar), por A. Hoyo, A. M. Moreno y J. González Parra.-- Características del humus a lo largo de una toposecuencia de andoso es en la lsla de Tenerife, por A. Polo, C. Gª Milla y F. Velasco.-- Relationship between organic carbon, nitrogen, phoophorus, sulphur and organic matter in some soils of Rajasthau, por L. L. Somani and S. N. Saxena.-- Meteorización experimental de sedimentos aluviales ácidos del valle del Guadalquivir, por Juan de Olmedo Pujoly Angelines Hernández.-- Predicting cation exchange capacity of soils from relative amount of clay and organic matter content, por L. L. Souzani.-- Influencia de la época de siembra de Triticum vulgare L. y grado de infección de Avena sterilis L. en la competencia de ambas especies, por R.González Ponce y V. Hernando Fernandez.-- Estudio de la capacidad competitiva de Avena sterilis L. contra Triticum vulgare L. en comparación a la de este ultimo consigo mismo, por R. González Ponce y V. H ernando Fernández.-- Estudio previo sobre la nutrición del Aguacate por análisis foliar, por S. Jaime Palacios, A. Aguilar Villalvilla y E. Esteban Velasco.-- Influencia del clururo sódico sobre la germinación de semillas de pimiemo (Capsicum annuum), por N. Caro, F. G. Fernández y A. Cerda.-- Aclareo químico de frutos en el olivar manzanillo de Sevilla, por A. Troncoso, I. Prieto y J. Liñan.-- Estudio de un sistema de drenaje a nivel parcelario en pasto Nariño (Colombia), por A. Alvarez López, A. Arias Henández y L. Legarda Burbano.-- Utilización digestiva de dietas con pesticidas, por Ciara Mª Rueda, J. F. Aguilar y J. Boza.—Trabajos recapitulativos.-- Genética de khizobium y de la fijación de nitrógeno, por J. Casadesús y J. Olivares.—Notas previa.-- Aplicaciones de la informática en el reconocimiento y evaluación de suelos