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ABSTRACT The objective of this study was to identify parameters, before the start of the breeding season, that affect the conception rate of precocious Nelore heifers through ultrasonographic ovarian evaluation and evaluation of weight and body condition score (BCS). A total of 407 heifers aged 404±69 days (≈14 months old), weighing 267.1±31.2 kg, and with mean BCS of 3.1±0.5, were used. Heifers were subjected to hormone treatment to induce cyclicity and, 30 days later, to a fixed-time artificial insemination (FTAI) program with three managements. Morphometric measurements of ovaries and ovarian structures were performed by transrectal ultrasonographic evaluation, as well as weighing and evaluation of BCS on D −30 and D0. Conception rate was evaluated 30 days after FTAI. The conception rate of heifers did not vary according to ovary diameter, weight, BCS, and age at first calving. However, heifers with the presence of follicle with a diameter > 6 mm at D −30 and D0 had a higher conception rate at the first FTAI. The presence of a dominant follicle greater than 6 mm at D −30 is an efficient complementary criterion to identify 14-month-old Nelore heifers with greater ability to conceive at the first FTAI before the breeding season. Antral follicle count performed on D −30 is not a good tool to predict fertility at the first FTAI, and the weight may not be a limiter to select heifers under good nutritional and health management.

Objetivou-se avaliar as características morfogênicas e estruturais do capim-piatã submetido à lotação intermitente e adubado com fontes de fósforo de diferentes solubilidades e adubação nitrogenada. Os tratamentos foram: controle (sem aplicação de adubo fosfatado); fonte de fósforo de lenta solubilidade (FNR); fonte de fósforo de rápida solubilidade (FSS) e fonte de fósforo de solubilidade mista (FSM), associados ou não à adubação nitrogenada. Foram realizadas medições de perfilhos pré-demarcados para avaliação das características estruturais e morfogênicas das plantas. Os dados foram analisados segundo um delineamento em blocos casualizados, em arranjo fatorial 4 x 2, dentro de cada estação do ano. As médias por quadrados mínimos dos tratamentos de adubação fosfatada foram comparadas com o tratamento controle pelo teste de Dunnet, e entre si pelo teste "t" e as médias de uso ou não de adubação nitrogenada foram comparadas entre si pelo teste "t" a 5% de significância. As fontes que contém fósforo prontamente disponível, como nos tratamentos FSS e FSM, promoveram maior alongamento de folhas e colmo, bem como maior número e aparecimento de folhas, o que evidencia a importância da disponibilidade de fósforo e nitrogênio no crescimento e desenvolvimento das plantas, confirmado pelo aumento na taxa de alongamento de folhas, do aparecimento foliar e alongamento de colmo. Assim, as adubações nitrogenada e fosfatada são alternativas para a persistência e competitividade da produção animal a pasto. Em relação à fonte, o uso de fontes de fósforo com solubilidade mista fornece esse nutriente a curto, médio e longo prazo. Palavras-chave: adubação de pastagens; caracterização morfogênica; produção em pasto; Urochloa brizantha cv.BRS Piatã.

The aim of this study was to evaluate the use of different mathematical models to describe the growth of lambs during the pre-weaning phase and the effect of sex on their growth curve. Data from 51 lambs (26 males and 25 females) with a genetic constitution of at least 50% Santa Inês breed were used. Lamb weight was monitored during the entire pre-weaning phase (91 days) by weighing the animals weekly on a scale suitable for sheep, to draw the body-weight growth curve. The adequacy of the models was evaluated by the coefficient of determination, simultaneous F-test for parameter identity, concordance correlation coefficient, root mean square error of prediction and decomposition of the mean square error of prediction. Pairwise mean square error of prediction analysis and delta Akaike information criterion were used to compare the models in terms of accuracy and precision. The evaluation of the adequacy of the tested models showed that the data predicted by the linear, quadratic and exponential models were similar (P > 0.05) to the observed data. In contrast, the monomolecular model generated predictions that could not be accepted as true. The linear and quadratic models showed better accuracy and precision. The first-degree linear model should be preferred over the other studied models to describe growth of sheep in the pre-weaning phase. Males and females exhibited distinct growth patterns.

ABSTRACT The aim of this study was to evaluate the effects of homeopathic additives and the non-ionophore antibiotic virginiamicin® on intake, digestibility, metabolic characteristics and carcase characteristics in Nellore bulls under supplemented grazing. Twelve uncastrated Nellore bulls were used, with an initial mean weight of 346.04 ± 13.33 kg and initial age of 20.00 ± 2.00 months. The animals were kept in individual paddocks of Urochloa decumbens Stapf. (syn. Brachiaria) and divided into two treatments: Lipomax® - supplement concentrate with homeopathic additives (Convert H®, Sodo 100®, Figotonus®) and a non-ionophore antibiotic (Virginiamycin®); Control - supplement concentrate containing the same protein content, but with no additives. The experiment was carried out in a completely randomised design. Intake, the apparent digestibility of the dietary constituents and the metabolic characteristics of the bulls were not affected by supplementation with additives (P>0.05). Lipomax® improved weight gain in the animals (P0.05). Supplementation with homeopathic additives and virginiamicina® had a positive effect on performance and on hot and cold carcase weight in grazing Nellore bulls.

This study aimed to evaluate the adequacy of seven non-linear models (France, Orskov and McDonald, Gompertz, exponential, logistic, two-pool exponential and two-pool logistic) in the adjustment of the curve and in the generation of parameters of cumulative gas production from five tropical feedstuffs (rice hulls, sugarcane, cassava chips, turnip by-product, and peach-palm by-product) used in ruminant nutrition. To this end, the feedstuffs were incubated in vitro in graduated glass syringes together with a buffer inoculum solution, in triplicate. Gas production was read at 0, 2, 4, 6, 8, 10, 12, 24, 26, 28, 30, 32, 36, 48, 52, 54, 56, 60 and 72 h of incubation. The data were used to generate the parameters of each model using the SAS statistical package. After the parameters were generated, the gas volume values were obtained at the aforementioned times, for each model, and these were compared with the values observed at incubation by using Model Evaluation System (MES) software. For the comparison, regression parameters were tested using Mayer’s test, in addition to the evaluation of the mean bias (MS), concordance correlation coefficient (CCC), and mean squared prediction error (MSPE). The France, Logistic, and Gompertz models, for rice hulls, and the Orskov and McDonald model, for cassava chips, were significant (P < 0.1) according to Mayer’s test, indicating lack of fit of the model. Besides presenting the lowest MSPE, the models that showed fit according to Mayer’s test were the two-pool logistic for rice hulls and cassava chips, and the two-pool exponential for sugarcane, turnip, and peach palm. Thus, the non-linear two-pool models are the most efficient in adjusting to the curve and in the generation of parameters of cumulative production of gases from the tested feedstuffs.

Three experiments were conducted with the objective of evaluating the effects of supplementation (concentrate or mineral supplementation), supplementation strategy (continuous or strategic supplementation) and gender class on the ingestive and diurnal behaviour of grazing beef cattle. To evaluate the effect of the supplementation (Experiment 1) and the gender class (Experiment 3) on their diurnal behaviour, behaviour visualisations were performed by two people at observation stations outside the picket area with the aid of binoculars. The animal behaviour was classified as: supplement intake, grazing, water intake, standing ruminating, standing idle, lying ruminating, lying idle and walking. To evaluate the effect of the supplementation strategy on the ingestive behaviour of the supplement (Experiment 2), refusals of the supplement were weighed for six consecutive days at different times (20, 40, 60, 90, 120, 180, 240, 480 and 1,440 minutes) after the concentrate was supplied. The intake of concentrate per animal, at each observation time, was calculated by subtracting the weight of the scraps at that time from the total weight of the batch of supplement provided on the day, and dividing the result by the number of animals in each batch. Finally, a logistic model was adjusted for each treatment. A 10% significance level was adopted for all statistical procedures. Concentrate supplementation reduced the time that the animals spent grazing. The continuous supplementation strategy affected the uniformity of the supplement intake speed, without affecting the average speed or the total supplement intake. The gender class of the animals also influenced their diurnal behaviour, castrated males spent more time lying, compared to females. The specificities of cattle behaviour should be considered when delineating the supplementation of grazing cattle, since the type of supplement, previous supplementation and gender class interfere with their behaviour.

Animal nutrition needs simple methodologies to be applied under field conditions, providing valid estimates of consumption and digestibility that can be used by both farmers and animal input industry. Thus, the search for new substances, provided in a practical way, quantified by simple and low-cost analytical methodologies, replacing external indicators (chromic oxide used as reference) would be well accepted by the scientific community. In this context, the aim of this study was to assess the supply of chorionic oxide by esophageal route or mixed in the diet and the use of kaolin as an indicator, under the same forms of administration, to estimate fecal production and digestibility using four castrated male Holstein cattle. The experimental design was a 4 × 4 Latin square design, with four experimental periods of 12 days and six-day intervals between periods. Treatments consisted of supplying chromic oxide by esophageal route (COer), kaolin by esophageal route (Kaoer), chromic oxide mixed to the diet (COdiet), and kaolin mixed to the diet (Kaodiet). The treatment Kaodiet allowed obtaining estimates of fecal production similar to the treatment COer. The treatment COdiet did not differ from the treatment COer (p > 0.05) considering all the assessed parameters, evidencing that the indicator chromic oxide can be supplied mixed directly in the diet without damaging the estimates of fecal production and digestibility. Under the studied conditions, kaolin was not an effective indicator to obtain accurate estimates of fecal production and further studies are needed to adjust the analytical techniques of aluminum extraction as well as to resolve some doubts regarding its digestion process.

This study aimed to assess the performance, carcass traits, and non-carcass components of feedlot finished Texel crossbred lambs from different residual feed intake classes (RFI). Forty-seven uncastrated male Texel crossbred lambs (¾ Texel + ¼ Pantaneira) tested here were 4-month-old with an initial weight of 29.9 ± 5.5 kg. The lambs were confined for 70 days for individual dry matter intake (DMI) and average daily gain (ADG) assessment. The diet containing corn silage was provided as roughage, while the concentrate consisted of corn grain, soybean meal, urea, and mineral mixture with a 40:60 roughage to concentrate ratio and 76.34% total digestible nutrients (TDN). After confinement for 70 days, the lambs were slaughtered to assess carcass traits and non-carcass components. Based on the RFI, lambs were divided into three classes according to the standard deviation (sd): Positive RFI (inefficient, 0.5 above the mean), Negative RFI (efficient, 0.5 below the mean), and Medium RFI (intermediate). Classes with Negative (efficient) and Positive RFI (inefficient) showed no differences in ADG (0.321 vs 0.306 kg; P > 0.05). Dry matter intake (g d-1), and percentage of body weight (BW) differed significantly between the RFI classes (P < 0.05). Compared to lambs in the inefficient class, those in the efficient class (Negative RFI) showed a 9% reduction in DMI and had the same ADG. The lambs in either Positive or Negative RFI classes showed no weight differences between non-carcass components (P > 0.05). The RFI classes showed no differences in shrunk body weight, hot carcass weight, hot dressing, and weight of commercial cuts (P > 0.05). They showed no differences in neck, shoulder + shank, loin, rack, flank steak, rack cap off, and leg weights (P > 0.05). Our results indicate that improvement in feed efficiency, as a function of the RFI index, does not compromise performance and carcass traits of Texel crossbred lambs.

Objetivou-se avaliar as características estruturais e morfogênicas do capim-convert HD364® em resposta à adubação fosfatada de diferentes solubilidades em água e ácido, durante as estações do ano. Utilizou-se o híbrido do gênero Urochloa spp, capim-convert HD364®, submetido a quatro tratamentos em delineamento em blocos ao acaso, sendo: Controle (sem adubação fosfatada), SS (Solubilidade rápida em água), FNR (Solubilidade lenta em ácido) e FH (Solubilidade mista). Semanalmente, durante as estações de primavera, verão e outono, foram realizadas as mensurações das características estruturais e morfogênicas descritas: TApF; TAlF; TSeF; TAlC; DVF; Filocrono e NFV. Observou-se efeito significativo (p < 0,05) na variável NFV com a utilização do FNR na estação de primavera, e na estação de outono observou-se efeito significativo nas variáveis TAlC e TAlF com a fonte de fósforo FH. Conclui-se que a fonte de fósforo de solubilidade mista pode ter influenciado na estrutura morfogênica do capim-convert HD364®, diminuindo o alongamento de colmo e aumento da lâmina foliar, podendo determinar facilidade no manejo de descanso no início do período seco.

This study aimed at evaluating carcass traits and meat quality of Nellore steers on pasture submitted to different dietary supplementation strategies. The 32 Nellore animals tested (8 ± 0.6 months) were raised under rotational grazing on Brachiaria brizantha cv. Piatã (syn. Urochloa brizantha cv. Piatã) pasture and distributed in four treatments: supply of mineral salt ad libitum in the growth and finishing phases (MSGF); concentrate supplementation only during the growth phase (CG); concentrate supplementation only during the finishing phase (CF) and concentrate supplementation the growth and finishing phases (CGF). The concentrated supplement was supplied at 0.5% of body weight and mineral ad libitum. The steers were slaughtered when more than 50% of the lot of each treatment reached 450 kg body weight. The mean the hot and cold carcass weight and subcutaneous fat thickness did not differ between treatments (P > 0.05). The calves the treatment CF and CGF showed a larger rib-eye area and higher ether extract levels in the Longissimus dorsi muscle than in MSGF and CG (P < 0.05). Mean shearing force was similar between treatments (P > 0.05). The use of feeding strategies on pasture with concentrate supplementation in the growth and finishing phases of Nellore cattle anticipates slaughter in 92 days and produces carcasses and meat with satisfactory traits.

Objetivou-se avaliar o crescimento dos componentes corporais de borregas mestiças alimentadas com níveis crescentes de concentrado na dieta e estabelecer o nível adequado de suplementação para produção de fêmeas para abate. Foram utilizadas 30 borregas lanadas, oriundas de cruzamentos com ovinos da raça Texel, alimentadas com feno de capim-Tifton 85 (Cynodon spp.) e quatro níveis de concentrado na dieta (20, 40, 60 e 80%). No início do experimento foi realizado abate para determinação da composição corporal de seis borregas. Os demais foram abatidos com aproximadamente 48 kg. Para o estudo do crescimento dos componentes em relação ao crescimento corporal dos animais foi utilizado o modelo CC = a x PCJb, onde CC = peso do componente corporal; a e b parâmetros das equações de crescimento e PCJ = peso corporal em jejum. A carcaça, músculos, ossos e trato gastrintestinal foram classificados como componentes de crescimento precoce (b < 1; P < 0,01). Foi observado efeito linear positivo dos níveis de concentrado sobre o crescimento da carcaça e gordura da carcaça (P < 0,05). A quantidade total de gordura aumentou com os níveis crescentes de inclusão de concentrado na dieta (P < 0,05). Recomenda-se a inclusão de 60% de concentrado na dieta de borregas em crescimento para produção de carcaças com precocidade para deposição de músculo e gordura. A inclusão de 20% de concentrado na dieta de borregas é o suficiente para produção de carcaças com máxima deposição de músculos e sem excesso de gordura.

Objetivou-se avaliar dietas com níveis crescentes de concentrado para borregas confinadas e estabelecer a proporção de concentrado ideal para maximizar a utilização dos nutrientes e o desempenho durante as fases de recria e terminação. Foram confinadas 24 borregas alimentadas com feno de capim-Tifton e níveis crescentes de concentrado na dieta (20, 40, 60 e 80%) para avaliação individual do consumo de matéria seca (CMS), digestibilidade dos nutrientes das dietas, ganho médio diário (GMD) e eficiência alimentar (EA). As borregas foram abatidas com 47 kg. Na fase de recria, o CMS não foi alterado (P>0,05) pela inclusão de concentrado nas dietas (1176 g/dia). Foi observado efeito quadrático dos níveis de concentrado (P0,05). O CDMS e o valor de NDT apresentaram comportamento quadrático (P0,05). Recomenda-se a inclusão de 71,50% de concentrado na dieta de borregas para maximizar o aproveitamento dos nutrientes e o desempenho na fase de recria e 72,3% de concentrado para fase de terminação.

The aim of this study was to evaluate the effect of different energy sources - corn, sorghum, and wheat bran - on performance, intake, digestibility, and nitrogen utilization efficiency of beef calves subjected to creep feeding. Thirty-four calves (12 males and 22 females) with initial age and weight of four months and 108±3.9 kg, respectively, were used in a randomized-block experimental design with four treatments and two blocks (males and females). Treatments were control (MM), a mineral mixture ad libitum; corn (C); corn + sorghum (C+S); and corn + sorghum + wheat bran (C+S+WB). Supplements contained approximately 20% crude protein (CP), and were fed in the amount of 0.5% of body weight. Supplemented animals had higher performance (P < 0.05) when compared with those on treatment MM. Supplementation increased (P < 0.05) the intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), non-fibrous carbohydrates (NFC), digestible neutral detergent fiber (dNDF), and digestible organic matter (dOM). The digestibility of NFC was higher (P < 0.05) in the supplemented treatments. The C+S and C+S+WB treatments provided increased digestibility (P < 0.05) of OM, CP, and NDFap. The synthesis of nitrogen compounds was higher (P < 0.05) in animals on treatment C as compared with those on the other supplemented treatments. Animals on treatments C+S and C+S+WB had higher (P < 0.05) nitrogen utilization efficiency compared with those on the other treatments. Concentrate supplementation improved the animal performance. The use of other energy sources (sorghum or wheat bran) in association with corn is recommended for suckling calves.

Objetivou-se ajustar e avaliar modelos Pará predição das proporções de Ossos, Músculos e Gordura da Carcaça de Borregas A Partir de Medidas obtidas in vivo, na Seção HH e 12ª costela. Como 30 Borregas lanadas, oriundas de Cruzamentos com ovinos da Raça Texel, foram confinadas, alimentadas com níveis crescentes de Concentrado. (20; 40; 60 e 80%) e abatidas com 37,70 ± 10,23 kg Pará Estimativa da proporção de Gordura (GC%) e músculo (MC%) na Carcaça foram ajustados modelos com SO percentuais de Gordura e músculo da 9ª a 11ª costela (Seção HH) UO da 12ª costela, acompanhados OU NÃO da espessura de Gordura (EGS mm) UO da área de olho de lombo da Carcaça (AOL cm2), respectivamente. a proporção de Ossos da Carcaça (OC%) foi Predito Cabelo percentual de Ossos na Seção HH UO da 12ª costela. Para predição in vivo, foram ajustadas Equações com peso corporal em jejum (PCJ), altura de cernelha (AC), EGS e AOL Medidas POR ultrassom. A GC% PODE Ser Estimada Pela EGS obtida na Carcaça EO Teor de Gordura na 12ª costela. O MC% PODE Ser Predito de forma acurada Mais considerando o Teor de músculo na Seção HH ea AOL da Carcaça. A Seção HH foi o modelo Mais acurado Paragrafo predição da OC%. Para Obtenção da GC% e MC% in vivo OS modelos devem Incluir PCJ e AC. O OC% in vivo PODE Ser Estimado a Partir do PCJ. Recomenda-se a utilização da Composição Física da 12ª costela Paragrafo Estimativa acurada da proporção de Gordura na Carcaça EO USO da Seção HH Paragrafo predição das proporções de músculo e Ossos na Carcaça. Para predição acurada das proporções de Gordura, músculo e Ossos de Borregas in vivo, o modelo DEVE apresentar peso corporal em jejum e Medidas de altura de cernelha.

A nutrição animal necessita de metodologias simples que possam ser aplicadas em condições de campo, que sejam capazes de fornecer estimativas válidas de consumo e digestibilidade e que possam ser utilizadas tanto pelos produtores rurais quanto pela indústria produtora de insumos para animais. Assim a busca por novas substâncias, fornecidas de forma prática, quantificadas por metodologias analíticas simples e de baixo custo em substituição aos indicadores externos (óxido crômico usado como referência) seriam bem aceitas pela comunidade científica. Neste contexto objetivou-se avaliar o fornecimento do óxido crômico via esofágica ou misturado na ração, e o uso do caulim como indicador, sob as mesmas formas de fornecimento, para estimar a produção fecal e digestibilidade, utilizando quatro bovinos machos castrados da raça Holandesa. Foram testados quatro tratamentos, distribuídos aos animais segundo um delineamento quadrado latino 4x4, sendo o primeiro aquele em que os animais foram submetidos ao fornecimento de óxido crômico fornecido via esofágica (OCesof), no segundo tratamento os animais receberam o caulim via esofágica (Caulesof), no terceiro o fornecimento do óxido crômico aos animais foi misturado à ração (OCrac) e no quarto tratamento o caulim foi administrado misturado à ração (Caulrac), em quatro períodos experimentais de 12 dias, com intervalos de seis dias entre os períodos. O tratamento Caulrac permitiu obter estimativas de produção fecal semelhante ao tratamento OCesof. O tratamento OCrac não diferiu do tratamento OCesof (p > 0,05) em nenhum dos parâmetros avaliados, evidenciando que o indicador óxido crômico pode ser fornecido misturado diretamente na ração sem prejudicar as estimativas de produção fecal e digestibilidade.

Consumers are more interested in having healthier and better quality products. The diet offered to animals can strongly affect the composition of meat. Thus, this study aimed to evaluate the effect of different levels of concentrate on lipid profile (in natura meat) and cholesterol content (in natura and cooked meat) of ewe lambs’ meat cuts. Therefore, twenty-four lambs with a mean weight of 23.1 ± 2.1 kg were confined and fed different levels of a concentrate (20, 40, 60 and 80%) for 120 days. The diets consisted of tifton hay and concentrate based on corn and soybean meal. The muscles triceps brachii (shoulder), longissimus dorsi (loin) and semimembranosus (leg) represented the respective cuts that were analyzed. Increased levels of concentrate decreased only C18:3 (5.82 to 0.20 mg/100 g) in meat and without affecting saturated fatty acids (SFA), unsaturated (UFA), monounsaturated (MUFA), polyunsaturated (PUFA), both desirable and total levels. Levels of concentrate had no effect on UFA/SFA (1.01), MUFA/SFA (0.97), PUFA/SFA (0.04) ratios, or the atherogenic (AI) and thrombogenic index (TI), nor on the content cholesterol in natura and cooked meat. The meat cuts had different lipid profiles, IA, IT and cholesterol content. Concentrate levels slightly alter the lipid profile and do not alter the cholesterol content, while meat cuts are different for these components.

The objective of this study was to evaluate performance and nutritional traits of beef cattle raised on pastures, castrated at different ages, with and without supplementation. Forty-four crossbred young bulls with predominance of Zebu breed at initial average age of 120±30 days were used in the experiment. Animals were distributed in a completely randomized design in a factorial arrangement with four ages of castration and two supplementation systems. The animals were distributed into four groups and placed on Brachiaria decumbens Stapf pastures, where they were fed concentrate supplementation or mineral salt ad libtum (control). Animals were castrated at 120, 240 and 360 days of age with average body weight of 115, 175 and 276 kg, castrated or not, in each supplementation group. Concentrate supplement composition and the amount supplied to the animals varied according to the time of the year and development phase of the animals. Trials were carried out to evaluate nutritional variables in each of the following phases: suckling, growth in the dry season and growth in the dry/rainy transition season. Concentrate supplementation improved the use of pasture, although it may have caused substitutive effect in all seasons evaluated. Castration of the animals before the dry season impaired animal development until the following dry/rainy transition season, especially when carried out during weaning. Concentrate supply may reduce some effects of this stress.

O objetivo neste estudo foi avaliar as condições nutricionais de tourinhos em aleitamento, a pasto, recebendo suplementação com concentrados proteicos durante a época de transição águas-seca. Foram utilizados 52 bezerros mestiços com idade média inicial de 130 dias. Os animais foram distribuídos em quatro lotes, alojados em piquetes de Brachiaria decumbens Stapf junto com suas mães, onde receberam uma das quatro estratégias de suplementação: três suplementos concentrados, ou sal mineral (controle). Os suplementos concentrados diferiram quanto ao nível de proteína. Após 45 dias, realizou-se a avaliação nutricional dos animais, que incluiu a estimação do consumo e da digestão de nutrientes e das características do metabolismo proteico. A estimação do consumo e da digestibilidade foi feita utilizando-se os indicadores: LIPE®, dióxido de titânio e fibra em detergente neutro indigestível. Realizou-se ainda coleta de amostras de urina e de sangue. O efeito de suplementação e os efeitos linear e quadrático do nível de proteína no concentrado foram avaliados pela decomposição da soma de quadrados em contrastes ortogonais, adotando-se α = 0,10. O consumo de concentrado substituiu parte do pasto ingerido pelos bezerros e aumentou a ingestão de proteína, a digestibilidade da matéria seca e matéria orgânica, o teor de nutrientes digestíveis totais e a excreção de nitrogênio na urina. O nível de proteína no suplemento tem efeito linear positivo sobre a ingestão diária de proteína, a digestibilidade de todos os nutrientes e o teor de nutrientes digestíveis totais e efeito quadrático sobre a excreção de nitrogênio na forma de ureia na urina.The objective of this study was to evaluate the nutritional status of grazing nursing young bulls supplemented with concentrates with different protein levels during the rainy-dry season transition. Fifty two crossbred Nellore calves with initial mean age of 130 days were divided into four lots, housed in paddocks of Brachiaria decumbens Stapf and received one of the four different supplementation strategies: three different concentrate supplements, or mineral salt (control). The levels of protein in the concentrate supplements varied. After 45 days, the nutritional evaluation of animals, which included the prediction of intake and digestion of nutrients and characteristics of protein metabolism, was made. The prediction of intake and digestibility used the indicators LIPE®, titanium dioxide and neutral detergent fiber indigestible. Urine and blood samples were collected too. The supplementation effect, and the linear and quadratic effects of the level of protein in the concentrate were evaluated by the decomposition of the sum of squares into orthogonal contrasts, adopting α = 0.10. The concentrate intake replaced part of the pasture ingested by the calves and increased protein intake, the digestibility of dry and organic matter, the total digestible nutrients content, and the nitrogen excretion in urine. The level of protein in the supplement has a positive linear effect on the daily protein intake, the digestibility of all nutrients and the total digestible nutrients content, and quadratic effect on the excretion of nitrogen as urea in the urine.

The objective of this study was to evaluate the use of different mathematical models to describe growth of grazing beef cattle. Data of 20 Nellore bulls with initial weight of 129±28.1 kg and final weight of 405±62.0 kg were used. The animals were randomly divided into four plots and placed on B. decumbens Stapf pastures. Three plots received concentrate supplement with different protein profiles and the fourth plot received only mineral supplement. Animals were weighed every 28 days to design growth curve of full body weight. Five mathematical models were evaluated to describe animal growth: Multiphase, Linear, Logarithmic, Gompertz and Logistic models. Assessment of adequacy of the models was performed by using coefficient of determination, simultaneous F-test for identity of parameters, concordance correlation coefficient, root of the mean square error of prediction and partition of the mean square error of prediction. The analysis of the pairwise mean square error of prediction and the delta Akaike's information criterion were used to compare the models for accuracy and precision. Evaluation of all the tested models showed that all of them were able to predict variability among animals. However, Gompertz, Logarithmic and Logistic models created individual predictions that were not satisfactory. Models differed from each other concerning accuracy and precision; the best were in the following order: Multiphase, Linear, Gompertz, Logarithmic and Logistic. The Multiphase model was more efficient than the others for description of grazing beef cattle growth.

The objective of this experiment was to estimate the requirements of energy, protein and macrominerals of grazing crossbreds calves, in Brachiaria decumbens Stapf pasture, castrated at different ages, with and without supplementation. Forty-seven young calves at initial age of 120±30.1 days and 115.3±1.97 kg of live weight were used. To estimate net energy requirements for weight gain, a regression equation between energy retained in the gain and empty body weight gain and metabolic empty body weight was obtained. For estimation of net protein requirements for weight gain, a regression equation was adjusted between protein retained in gain and empty body weight gain and energy content of this gain. Net requirements of Ca, P, Mg and Na for weight gain were determined by the equation Y' = a.b. Xb-1, in which a and b represent the intercept and the coefficient of the alometric equation of macromineral body content prediction, respectively. Neither castration nor concentrate supplementation affects body weight gain net requirements, except the ones of Ca, which were higher for non-castrated animals.

Objetivou-se avaliar equações adotadas pelo NRC e Detmann para estimar o conteúdo energético de subprodutos agrícolas e agroindustriais. Foram avaliados subprodutos de abacaxi, cacau, dendê, feijão, girassol, goiaba, mandioca casca, mandioca haste, mandioca rama, mamão, manga, maracujá, nabo e farelo de glúten de milho. Todos os animais receberam silagem de milho e mistura ureia/sulfato de amônio (9:1) para que as rações com os dois níveis de cada subproduto se mantivessem isonitrogenadas. Entre os modelos de predição da proteína bruta digestível (PBad), o modelo Detmann 2 apresentou diferença pelo teste de hipótese para nulidade conjunta (THNC), enquanto as estimativas pelos modelos NRC e Detmann 1 foram similares às obtidas pelas observações in vivo. Para extrato etéreo digestível (EEad), carboidratos não-fibrosos digestíveis (CNFad) e fibra em detergente neutro digestível (FDNd), as estimativas obtidas pelo modelo proposto pelo NRC diferiram, pelo teste de significância da hipótese de nulidade conjuntas, das observações in vivo e o melhor ajustamento foi obtido pelo modelo sugerido por Detmann, tendo como consequência, o valor. No entanto, entre todas as frações digestíveis, a FDNd foi a que apresentou maior dispersão dos pontos em relação à linha de equalidade. Os modelos NRC e Detmann podem ser considerados eficientes em predizer nutrientes digestíveis totais (NDT) e energia digestivel (ED), pois as estimativas não diferem dos valores observados, contudo apresentam também grande dispersão dos pontos em relação à linha de equalidade. Recomenda-se usar os modelos propostos por Detmann para predizer as frações digestíveis da PB, EE e dos CNF em subprodutos agrícolas e agroindustriais.The objective of this work was to evaluate the equations adopted by the NRC and Detmann to estimate the energy content of agricultural and agroindustrial byproducts. It was evaluated byproducts of pineapple, cocoa, palm oil, beans, sunflower, guava, cassava bark, cassava stem, raw cassava, papaya, mango, passion fruit, turnip and corn gluten meal. All animals received corn silage and the mixture urea/ammonium sulfate (9:1) so rations with the two levels of each byproduct remained isonitrogenous. Among the models for digestible crude protein prediction (CPad), Detmann 2 model presented difference by the hypotheses test for joint null while estimates by the NRC and Detmann 1 models were similar to those obtained by in vivo observations. For digestible ether extract (EEad), digestible non-fibrous carbohydrates (NFCad) and digestible neutral detergent fiber (NDFd), the estimates obtained by the model proposed by the NRC differed, by the test of significance of hypotheses of joint null, to in vitro observations and the best adjustment was obtained by the model suggested by Detmann, having as a consequence, the value. However, among all the digestible fractions, NDFd presented the greatest dispersion of points regarded to equality line. NRC and Detmann models can be considered as efficient in predicting total digestible nutrients (TDN) and digestible energy (DE) because the estimates do not differ from the observed values, however they also present great dispersion of the points regarded to equality line. It is recommended to use the models proposed by Detmann for predicting digestible fractions of crude protein, ether extract and non fibrous carbohydrates on agriculture and agroindustrial byproducts.

Com o objetivo de avaliar a composição do ganho e as curvas de crescimento de componentes corporais, foram utilizados 36 garrotes inteiros, sendo 12 Nelore, 12 ½ Holandês x ½ Zebu e 12 ½ Caracu x ½ Zebu. Animais recria (peso médio inicial de 226 kg) e terminação (peso médio inicial de 332 kg) foram mantidos em regime de confinamento até o abate, de acordo com o peso vivo: 310 a 340 kg para os animais recria e 420 a 470 kg para os terminação. Foi fornecida a mesma dieta ad libitum a todos os animais. De cada animal abatido pesaram-se os componentes corporais e coletou-se uma amostra da seção HH para avaliação dos componentes físicos das carcaças. Para predição dos conteúdos de músculo, tecido adiposo e ossos da carcaça dos animais e do total de órgãos e de tecido adiposo visceral (TADvis) no corpo vazio, adotou-se a equação de regressão do logaritmo do conteúdo destes componentes no corpo vazio, em função do logaritmo do peso do corpo vazio - PCVz (ARC, 1980). Derivando-se as equações acima, obtiveram-se as equações de predição da participação dos componentes corporais no ganho de 1 kg de peso de corpo vazio (GPCVz). Dentro de cada grupo genético, todas as características avaliadas foram significativamente correlacionadas com o PCVz dos animais. O tecido ósseo foi o de maturidade mais precoce dentro da carcaça. Entre os componentes corporais estudados, o TADvis foi o de maior alometria para os animais ½ Holandês x ½ Zebu. A aptidão leiteira do grupo genético reduziu a participação da carcaça no GPCVz, na medida em que aumentou a participação dos órgãos neste ganho. A alometria positiva do tecido muscular, a menor velocidade de incremento no ganho de tecido adiposo da carcaça e a reduzida velocidade de crescimento do tecido ósseo, na fase de terminação dos animais Nelore, podem ser explicados por ganho compensatório realizado por estes animais.Thirty-six young bulls (12 Nellore, 12 crossbed ½ Holstein x ½ Zebu, and 12 crossbred ½ Caracu x ½ Zebu) were used to evaluate the composition of the gain and the growth curves of corporal components. The growing animals had initial average weight of 225 kg, and the finishing ones, initial average weight of 332 kg. The animals were maintained in confinement regime to reach 310 to 340 kg of weight for the growing animals and 420 to 470 kg of weight for the finishing ones. A same diet was supplied ad libitum to all the animals. The corporal components of each animal were weighed and a representative sample of the section HH for evaluation of the carcasses physical components was collected. The contents of carcass muscle, carcass fatty tissue and carcass bone and the total of organs and visceral fatty tissue (VFT) in empty body were predict by the equation of regression of the logarithm of the content of these corporal components in the empty body, on the logarithm of the empty body weight - EBW (ARC, 1980). By deriving the equations above, the equations of prediction of the participation of the corporal components in the gain of 1 kg of empty body weight (EBWG) were obtained. In each genetic group, all the characteristics were significantly correlated with the EBW of the animal. The results showed that the bone tissue was of more precocious maturity in the carcass. VFT was the highest alometric coefficient to the ½ Holstein x ½ Zebu animals. The milk aptitude reduced the participation of the carcass in the EBWG, as the participation of the organs in this gain increased. The positive alometric development of muscle, the smaller increase velocity in the carcass fatty tissue gain and the smaller decrease velocity in the carcass bone gain in the finishing phase, in Nelore animals may be caused by Nelore compensatory growth.

Para se avaliar o desempenho (ganho de peso e conversão alimentar), o consumo de nutrientes e a digestibilidade aparente de vários nutrientes, foram utilizados 36 garrotes inteiros, 12 Nelore, 12 ½ sangue Holandês-Nelore e 12 ½ sangue Caracu-Nelore. Foram utilizados animais em recria, com peso inicial próximo a 205 kg, e animais em terminação, com aproximadamente a 310 kg. Os animais foram mantidos em regime de confinamento até o abate, realizado de acordo com peso: 310 a 330 kg PV para os animais em recria e 450 a 480 kg PV para aqueles em terminação. Foi fornecida a mesma dieta a todos os animais, com 50% da matéria seca à base de concentrado e o restante de silagem pré-seca de coastcross. Os animais foram alimentados ad libitum e pesados a cada 28 dias. Foram retiradas amostras semanais de ração e de sobras individuais, que foram agrupadas em amostras para cada período de 28 dias. Realizou-se um ensaio de digestibilidade no 50º dia de experimento. Não se observou efeito significativo de grupo genético sobre o consumo de matéria seca (6,06 kg/dia para recria e 9,05 kg/d para a terminação), ganho de peso vivo (0,994 kg/d e 1,293 kg/d para a recria e terminação, respectivamente) ou para os coeficientes de digestibilidade dos nutrientes analisados. Os animais ½ sangue Caracu-Nelore da categoria recria apresentaram conversão alimentar 30% maior que aqueles dos demais grupos genéticos. A ingestão de NDT esteve, em média, 26% abaixo dos valores preditos pelo NRC (1996) para animais com estes pesos vivos e valores de ganho de peso.Thirty-six young bulls (12 Nellore, 12 ½ crossbred Holstein x Nellore, and 12 crossbred ½ Caracu x Nellore) were used to evaluate weight gain, feed conversion, ingestion capacity and apparent digestibility of various nutrients. We use growing and finishing animals. The growing animals had initial weight of 205 kg, and the finishing ones, initial weight of 310 kg. The animals were fedlot to reach the weight of 310 to 330 kg for the growing animals and 450 to 480 kg for the finishing ones. The same diet was supplied to all animals, with concentrate level of 50% in the dry matter and 50% of coastcross hay silage. The animals were fed ad libitum and weighed every 28 days. Weekly samples of ration and individual orts were removed and composed for each period of 28 days. A digestibility test was done at the 50th day of the experimental period. A significant effect of genetic group was not observed on dry matter intake (6.06 kg/day for the growing animals and 905 kg/d for the finishing ones), live weight gain (0.994 and 1.293 kg/d for growing and finishing animals), or digestibility coeficient of evaluated nutrients. The crossbred ½ Caracu x Nellore growing animals presented higher feed conversion (30%) than the other genetic groups. The TDN daily ingestion was 26% smaller than the NRC (1996) predictions.

Com os objetivos de avaliar a composição corporal e identificar características corporais mensuráveis capazes de estimar o tamanho relativo de componentes corporais, foram utilizados 36 garrotes inteiros, sendo 12 Nelore, 12 ½ Holandês x ½ Zebu e 12 ½ Caracu x ½ Zebu. Em cada grupo genético, havia seis animais de cada fase de produção: recria e terminação, com peso inicial próximo a 225 kg e 330 kg, respectivamente. Os animais foram mantidos em regime de confinamento até o abate, realizado de acordo com o peso: 310 a 340 kg PV para os animais na fase de recria e 420 a 470 kg PV para aqueles na fase de terminação. Foi fornecida a mesma dieta a todos os animais, com 50% da matéria seca à base de concentrado e 50% de silagem pré-seca de coastcross. Utilizou-se um fator geral de 0,8693 para conversão do peso vivo em peso de corpo vazio (obtido a partir dos dados de todos os animais do experimento). Animais provenientes de seleção para corte na categoria terminação apresentaram maiores rendimentos de carcaça (59,2%) que aqueles de origem leiteira (56,33%). Grupos genéticos de raças com aptidão leiteira mostraram tamanhos relativos de órgãos 9% maior, 21% menos tecido adiposo na carcaça, bem como maior participação da gordura interna no total de tecido adiposo corporal. Em razão das baixas correlações encontradas, não parece confiável estimar os tamanhos relativos dos componentes corporais estudados a partir das características corporais mensuráveis analisadas.To evaluate the body composition, and to identify measurable body characteristics capable to estimate the relative size of body components, 36 young bulls (12 Nellore, 12 ½ Holstein x ½ Zebu, and 12 ½ Caracu x ½ Cebu) were used. In each genetic group, six animals of each production phase were used: growing animals with initial weight of 225 kg and the finishing ones with initial weight of 330 kg. The animals were maintained in confinement regime to reach 310 to 340 kg of weight for the growing animals and 420 to 470 kg of weight for the finishing ones. The same diet was fed to all the animals, with concentrate level of 50% in the dry matter and 50% of coastcross hay. A general factor of .8693 was adopted to conversion of live weight in empty body weight (obtained with the records of all the animals in the experiment). Animals from a beef selection origin, in finishing group, presented higher dressing percentage (59.2%) that those of milk selection origin (56.33%). Genetic groups originating from breeds with milk aptitude showed higher relative sizes of organs (9% more), 21% smaller total fatty tissue in carcass, as well as higher participation of internal fatty tissue in total fatty tissue. Despite of the low correlations, it is not reliable to estimate the relative sizes of the body components studied from the analyzed measurable body characteristics.

RESUMOO objetivo deste estudo foi avaliar o desempenho de bezerros lactentes submetidos a dietas com e sem feno de leguminosas. O período experimental foi de 60 dias, sendo o fornecimento dos alimentos sólidos ad libitum e disponibilizados a partir do 10º dia de vida do animal, e o leite in natura fornecido de maneira restrita na porção de 4 litros/dia, divididos em duas refeições equitativas. Foram avaliadas as dietas: ração concentrada; ração concentrada mais feno de leucena (Leucaena leucocephala Lam. De Wit) e ração concentrada mais feno de alfafa (Medicago sativa L.). Utilizou-se 15 animais Girolando, distribuídos em três tratamentos, em um delineamento em blocos ao acaso desbalanceados. Os parâmetros avaliados foram peso corpóreo inicial (nascimento - PCI) e final (PCF), ganho médio diário (GMD), alturas de cernelha (AC) e garupa (AG), perímetro torácico (PT), consumo de matéria seca (CMS) e conversão alimentar (CA). Não foram observadas diferenças no desempenho dos animais em relação aos tratamentos, com médias 32,9 (±2,9) kg; 67,7(±1,2) kg; 0,58(±0,02) kg; 13,1(±0,5) cm; 13,7(±0,3) cm; 20,6(±0,7) cm; 0,46(±0,1) kg e 0,79(±0,1), para os parâmetros PCI, PCF, GMD, AC, AG, PT, CMS e CA, respectivamente. As exigências nutricionais de bezerros lactentes são atendidas com o fornecimento de leite e ração concentrada, não havendo necessidade de inclusão de feno de leguminosas na dieta.

ABSTRACT We evaluated performance, non-carcass components, and carcass characteristics of crossbred Texel lambs in different categories of residual intake and gain (RIG). We assessed 77 crossbred (¼ Pantaneira and ¾ Texel) non-castrated animals in two study phases. The first phase included 47 lambs with an initial average weight of 29.9±5.5 kg, and the second phase included 30 lambs with initial average weight of 22.4±3.3 kg. Dry matter intake (DMI) and average daily gain (ADG) were evaluated for 70 days. Animals were divided into three groups in terms of efficiency: efficient (high RIG), intermediate (medium RIG), or inefficient (low RIG), based on the standard deviation of the mean for the RIG variable. We measured the yield of non-carcass components, carcass characteristics, and yield of meat cuts. Efficiency group had no association with DMI, nor with initial and final body weights of the animals. The ADG of efficient (0.310 kg day−1) and intermediate (0.290 kg day−1) animals was greater than observed in inefficient (0.260 kg day−1) animals. Lambs in the efficient and intermediate groups had significantly higher levels of all efficiency indicators evaluated. Efficient and intermediate animals yielded significantly more wool/skin in comparison with lambs in the inefficient group. Animals with high RIG also had lower relative weight of testicles/scrotal sac in comparison with inefficient animals. Fat deposition in the omentum and mesentery as well as total fat were decreased in efficient animals. No significant differences occurred among groups regarding carcass characteristics and yield of meat cuts. The RIG index allows for the identification of lambs with higher growth rates and greater wool/skin yield and lower proportion of visceral fat.