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Crossbreeding represents an important technique to improve growth, beef quality and adaptability in beef production systems in tropical countries. The aim of this study was to evaluate sire and dam breed effects on performance and carcass traits of crossbred cattle produced in a tropical environment. Heifers and steers were evaluated during the pre-weaning, the post-weaning (n = 173) and the finishing phase (n = 123). Animals were produced by mating Nellore (N_N), Angus × Nellore (A_N) and Caracu × Nellore (C_N) dams with Braford, Charbray and Caracu sires. After weaning, animals were raised grazing on Marandu grass for 12 months; thereafter they were housed in individual pens and finished in a feedlot, receiving a total mixed ration. Ultrasound carcass evaluations were performed to determine ribeye area (R_A), backfat thickness (B_T) and rump fat thickness (R_T). A_N progeny were heavier at birth than N_N (P < 0.05), and Braford progeny had greater birth BW than Caracu (P < 0.05). Greater weaning BW was observed in the A_N and C_N offspring compared to N_N (P < 0.01). Greater average daily gain during the post-weaning period was verified in the N_N progeny compared to C_N (P < 0.05). No dam or sire breed effects were observed for BW at the end of the post-weaning period (P > 0.05). Progeny of N_N cows had greater B_T (P < 0.05) and R_T (P < 0.01) at the end of the post-weaning period in relation to C_N. Greater R_A was observed in the Caracu progeny than in the Braford (P < 0.05), which showed greater R_T than the Charbray progeny at the end of the post-weaning period (P < 0.05). No dam or sire breed effects were verified for final BW at the feedlot or for feed efficiency traits (P > 0.05). A_N progeny were superior in final B_T compared to C_N (P < 0.01), and Braford progeny had greater R_T at the end of finishing than Charbray (P = 0.05). The use of crossbred dams allows an increase in productivity until weaning, but this is not maintained in the post-weaning and finishing periods. The use of Braford sires produces similar growth performance in the different stages of the production system to those seen with Charbray and Caracu sires but generates animals with higher fat thickness at the end of finishing, which may improve carcass quality and commercial value.

This work was carried out with the objective of evaluating the effects of different levels of replacement of whole grain corn by pelleted soybean hulls in high concentrated diet, without long fiber use, on intake, productive performance and economical viability of feedlot lambs production. Twenty four Texel lambs, 12 males and 12 females of the same age, with average weight of 23 kg, distributed in 12 stalls, in a completely randomized design, were used. The treatments consisted of replacement of whole grain corn by pelleted soybean hulls, at levels of 0% (SH0), 15% (SH15) and 30% (SH30). Dry matter (DM) (kg day -1

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ResumoEste estudo teve por objetivos avaliar o desempenho produtivo de cordeiros até o desmame, filhos de ovelhas de diferentes grupos genéticos e submetidas a diferentes suplementações alimentares antes e durante a estação de monta. Foram utilizados 126 cordeiros, sendo 11 ½ Corriedale + ½ Texel, 73 Hampshire Down, 26 Ile de France e 16 Suffolk, nascidos em dois anos consecutivos, provenientes de ovelhas submetidas a três tratamentos: T1 -sem suplementação, T2 -suplementação com 600 g de milho triturado por dia, e T3 -suplementação com 600 g de uma mistura de 75% de milho e 25% de farelo de soja; mantidas em pastagem de Coast-cross. Os dados de pesos e ganhos de peso foram analisados individualmente e por prole (soma dos gêmeos). O flushing não influenciou os pesos e ganhos de peso. Cordeiros gêmeos, na análise individual, apresentaram pesos e ganhos de pesos menores do que cordeiros únicos, porém, na análise por prole, na soma dos gêmeos observou-se maiores pesos e ganhos do que em cordeiros únicos. Verificaram-se diferenças nos pesos e ganhos de peso por influência dos grupos genéticos e por sexo, onde os machos foram mais pesados e ganharam mais peso do que as fêmeas. Cordeiros gêmeos apresentaram maior mortalidade que cordeiros únicos. Apesar do flushing prover maior produção de cordeiros, não se verificou um retorno econômico considerável. Conclui-se que o flushing alimentar não influencia o desempenho dos cordeiros, e que cordeiros gêmeos apresentam maior taxa de mortalidade que cordeiros únicos, sendo o flushing alimentar pouco viável economicamente. Palavras-chave: Ganho de peso, gêmeos, ovinos, raças, suplementação alimentar AbstractThe objectives of this study were to analyze the productive performance of lambs, out of ewes of different genetic groups and submitted to different feeding managements before and during the mating season, from birth until weaning. One hundred and twenty-six lambs were used, from the genetic 1 Profs. Drs.,