RESUMO -O objetivo deste trabalho foi avaliar o efeito de diferentes níveis de volumoso nas dietas sobre os consumos e as digestibilidades aparentes de matéria seca (MS), matéria orgânica (MO), proteína bruta (PB), extrato etéreo (EE), fibra em detergente neutro (FDN), carboidratos totais (CHOT) e energia bruta (EB) e sobre os consumos de nutrientes digestíveis totais (NDT). Trinta e cinco bezerros da raça Holandesa puros por cruzamento, não-castrados, com idade média de 60 dias e peso vivo inicial de 78 kg, foram distribuídos em delineamento inteiramente casualizado, com nove repetições por dieta, exceto para a dieta com 10% de volumoso, com oito repetições. Os animais foram alimentados à vontade com dietas contendo níveis de 10, 25, 40 e 55% de volumoso, na base da MS, usando-se feno de capim coast-cross (Cynodon dactylon), fubá de milho e farelo de soja, os quais constituíram dietas com aproximadamente 16% de PB. O óxido crômico foi usado para obtenção das estimativas dos fluxos de MS fecal. Os carboidratos totais foram obtidos por 100 -(%PB + %EE + %Cinzas). O consumo de NDT foi obtido por (cPB -PBf) + 2,25 (cEE -EEf) + (cCHOT -CHOTf), em que c significa consumo e f, excreção fecal. Não houve efeito dos níveis de volumoso nas dietas sobre os consumos de MS e MO (kg/ dia, % PV e g/kg 0,75 ) e de PB e CHOT (kg/dia e % PV). O consumo de FDN (kg/dia, %PV e g/kg 0,75 ) aumentou, enquanto o consumo de EE e NDT (em kg/dia e %PV) reduziu linearmente em função dos níveis de volumoso na dieta. Houve efeito linear decrescente sobre as digestibilidades aparentes de MS, MO, PB, EE, CHOT e EB, em função do aumento dos níveis de volumoso nas dietas, enquanto a digestibilidade aparente da FDN não foi influenciada. Os consumos de EE, FDN e NDT e as digestibilidades aparentes de MS, MO, EE, PB, CHOT e EB foram influenciados pelos níveis de volumoso nas dietas. Palavras-chave: bezerro holandês, digestibilidade, ingestão, nível de volumoso Intake and Apparent Digestibility Coefficients in Calves Fed Diets with DifferentForage Levels ABSTRACT -This work was to evaluate the effect of different forage levels in the diet on the intake and apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), neutral detergent fiber (NDF), total carbohydrate (CHO), gross energy (GE) and total digestible nutrients (TDN). Thirty five pure Holstein bull calves, 60 days old with initial average live weight (LW) of 78 kg, were allotted in a completely randomized experimental design with nine replications per diet, except for the 10% forage diet, with eight replicates. The animals were ad libitum fed with diets contained 10; 25; 40; and 55% of forage, on the DM basis, using chopped coast-cross (Cynodon dactylon) grass, ground corn and soybean meal, which constitute diets with approximately 16% CP. The chromium oxide was used to obtain the fecal DM excretion estimates. The total carbohydrate was calculated as 100 -(%CP + %EE + % ash). The TDN was calculated as (cCP -fCP) + 2.25 (cEE -fEE) + (cCHO -fCHO), wh...

RESUMO -Objetivou-se estimar parâmetros genéticos e selecionar genótipos de amendoim forrageiro para maior cobertura do solo e produção de biomassa aérea durante o período de estabelecimento nas condições ambientais do Acre. A área experimental foi estabelecida em dezembro de 2005. O experimento foi realizado em delineamento de blocos ao acaso com quatro repetições utilizando-se 21 genótipos de amendoim forrageiro, incluindo três cultivares (Amarillo, Alqueire 1 e Belmonte). A seleção dos genótipos foi realizada considerando a cobertura do solo e a produção de matéria seca. As avaliações Unbiased Prediction (BLUP), according the methodology of mixed models. Presence of genetic variability was verified for both traits. Individual heritabilities in the wide sense were of medium magnitude, presenting values of 0.36 to 0.58 for the traits ground cover and dry matter production, respectively. The largest variability among genotypes for ground cover occurred between the 12 th and 16 th week after planting, indicating that this interval is the most appropriate to select genotypes that cover the ground more quickly. Genotypic values for dry matter production ranged from 1,609 to 4,132 kg/ha for genotypes BRA 015083 and BRA 040550, respectively. The genotypes selected for greater ground cover and aerial biomass production during establishment period were Belmonte, Amarillo, BRA 040550, BRA 039187, Alqueire 1, BRA 039799 and BRA 035033.

RESUMO -Modelos de regressão aleatória foram utilizados neste estudo para estimar parâmetros genéticos da produção de leite no dia do controle (PLDC) em caprinos leiteiros da raça Alpina, por meio da metodologia Bayesiana. As estimativas geradas foram comparadas às obtidas com análise de regressão aleatória, utilizando-se o REML. As herdabilidades encontradas pela análise Bayesiana variaram de 0,18 a 0,37, enquanto, pelo REML, variaram de 0,09 a 0,32. As correlações genéticas entre dias de controle próximos se aproximaram da unidade, decrescendo gradualmente conforme a distância entre os dias de controle aumentou. Os resultados obtidos indicam que: a estrutura de covariâncias da PLDC em caprinos ao longo da lactação pode ser modelada adequadamente por meio da regressão aleatória; a predição de ganhos genéticos e a seleção de animais geneticamente superiores é viável ao longo de toda a trajetória da lactação; os resultados gerados pelas análises de regressão aleatória utilizandose a Amostragem de Gibbs e o REML foram semelhantes, embora as estimativas das variâncias genéticas e das herdabilidades tenham sido levemente superiores na análise Bayesiana, utilizando-se a Amostragem de Gibbs.Palavras-chave: análise Bayesiana, caprinocultura leiteira, componentes de variância, correlação genética Estimation of genetic parameters for milk yield of dairy goats by random regression analysis using Gibbs SamplingABSTRACT -Random regression models were used to estimate genetic parameters for test-day milk yield (PLDC) of Alpine dairy goats, implemented by Bayesian methods with Gibbs Sampling. The estimates were compared with those obtained by random regression analysis, using REML. Heritability estimates obtained by Bayesian analysis ranged from 0.18 to 0.37, while those obtained by REML ranged from 0.09 to 0.32. Genetic correlations between yields of close test days approached the unit, but decreased gradually as the interval between test days increased. Results indicated that random regression models are appropriate to model the covariance structure of PLDC and to predict genetic gains and select animals along the lactation trajectory of dairy goats. Results obtained by Bayesian and REML approaches were similar, although genetic variance and heritability estimates were slightly higher with Bayesian methods.

Forage peanut improvement for use in grass–legume mixtures is expected to have a great impact on the sustainability of Brazilian livestock production. Eighteen cloned Arachis spp. ecotypes were evaluated under clipping in a Brazilian Cerrado region and results analysed using a mixed model methodology. The objective was to estimate genetic and phenotypic parameters and to select the best ecotypes based on selection index applied on their predicted genotypic value. The traits of total dry‐matter (DM) and leaf DM yield presented moderate (0·30 < hg2 < 0·50) to high (>0·50) broad‐sense heritability, in contrast to the low genetic variability in nutritional quality‐associated traits. Ecotypes of Arachis spp. contained average crude protein concentrations of 224 g kg−1 DM in leaves and 138 g kg−1 DM in stems, supporting the potential role of these species to overcome the low protein content in Cerrado pastures. The correlations between yield traits and traits associated with low nutritional value in leaves were consistently significant and positive. Genetic correlations among all the yield traits evaluated during the rainy or dry seasons were significant and positive. The ecotypes were ranked based on selection index. The next step is to validate long‐term selection of grass–Arachis in combination with pastures under competition and adjusted grazing in the Cerrado region.

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Although alfalfa (Medicago sativa L.) is a leguminous herbage widely used in temperate regions as animal feed, there is not much research in tropical regions to develop cultivars adapted to these environmental conditions. The utilization of adapted cultivars with adequate management practices is important to improve productivity, quality and persistence of cultivated pastures. The objectives of this study were to verify the genetic variability among alfalfa cultivars and to rank them using mixed model methodology. A total of 35 alfalfa cultivars were evaluated in the rainy and dry seasons, from 1996 to 2000, in plots of 2.8 m 2 in Sertãozinho, São Paulo, Brazil. The experimental design was a randomized complete block with three replications. Longitudinal data of dry matter yield were analyzed using PROC MIXED of SAS w System. Several covariance structures were tested and the spherical spatial structure was selected. The results show that the genetic variability was statistically significant only for the dry season. Moreover, the interaction among cultivars and harvests variance was highly significant for both seasons. The empirical best linear unbiased predictions of cultivar effects were obtained, allowing for the selection of the superior cultivars MH 15, 5715, SW 8210, Rio, High, 5888, Monarca, Victoria, Florida 77 and Falcon. Crioula, the most common cultivar in Brazil, showed low forage potential in Sertãozinho. Results indicate potential for use of more productive cultivars of alfalfa to produce animal feed in tropical environments.

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.5 and 8.8 t DM/ha/yr, respectively) throughout, while cv. BRS Mandobi and accession 6 were the worst (5.7 and 5.6 t DM/ha/yr). Most genotypes maintained ground cover above 80% throughout the study but cv. BRS Mandobi plus accessions 6 and 8 had declined to 60% or less by the third year. Mean crude protein concentration overall was 166 g/kg with a range of 154-182 g/kg among genotypes. There was no major genotypic variation in mineral concentrations, which in all cases were considered marginal to adequate for tropical forage legumes. In conclusion, accessions 2 and 4 (BRA-039799 and BRA-039187, respectively) of A. pintoi are considered the most promising forage peanut options under the edaphoclimatic conditions of the experimental site. More effort is needed to improve seed set in these genotypes to increase adoption by farmers. Their persistence under grazing and impact on production should also be demonstrated. Keywords:Arachis pintoi, Arachis repens, crude protein, digestibility, minerals. ResumenEn Planaltina, Distrito Federal, Brasil, se evaluaron la producción de forraje, el valor nutritivo, la cobertura del suelo y la concentración mineral de 10 genotipos de Arachis spp. durante 3 años. Las parcelas experimentales se dispusieron en un diseño de bloques completos al azar con 4 repeticiones. Los tratamientos consistieron en 5 genotipos de A. pintoi (accesiones 2, 4, 5, 6 y 8), 2 genotipos de A. repens (accesiones 1 y 7), 1 híbrido A. pintoi × A. repens (accesión 3) y 2 cultivares de A. pintoi, BRS Mandobi y Belmonte. Todos los genotipos presentaron buen establecimiento y buena cobertura del suelo en el primer año. Considerando los 3 años del experimento, el cultivar (cv.) Belmonte y las accesiones 2 y 4 presentaron los rendimientos de materia seca (MS) más altos, con promedios de 8.8, 8.5 y 8.8 t MS/ha por año, respectivamente, mientras que cv. BRS Mandobi y la accesión 6 fueron los menos productivos, con promedios de 5.7 y 5.6 t MS/ha por año, respectivamente. La mayoría de los genotipos mostraron una cobertura del suelo superior a 80% durante la duración del estudio; no obstante el cv. BRS Mandobi y las accesiones 6 y 8 presentaron una reducción al 50-60% al finalizar el tercer año. En total, la concentración promedio de proteína cruda fue de 166 g/kg con un rango de 154-182 g/kg entre genotipos. Las concentraciones de minerales no mostraron mayores variaciones entre genotipos y se consideraron marginales a adecuadas para leguminosas forrajeras tropicales. En conclusión, las accesiones 2 y 4 de Fernandes, A.K.B. Ramos, M.A. Carvalho, G.A. Maciel, G.M.L. de Assis and G.J. Braga Tropical Grasslands-Forrajes Tropicales (ISSN: 2346-3775)A. pintoi (BRA-039799 y BRA-039187, respectivamente) mostraron ser las opciones más promisorias bajo las condiciones edafoclimáticas del sitio experimental. Se requieren esfuerzos para mejorar la producción de semilla de estos materiales para lograr una mayor adopción por los productores. Además su persistencia bajo pastoreo y su impacto en la producción deben demostrarse.