The objective of this study was to compare growth from birth to slaughter of different breed groups that were raised in Rio Grande do Sul, Brazil and estimate the consequent breed additive and heterosis effects. Caracu (C), Hereford (H), and Nelore (N) sires were mated with Angus (A) dams, and A sires were mated with H and N dams to produce a first generation of crossbred progeny that was contemporary with purebred A, H, and N calves. Heifers from this first generation (G₁) were mated with Brangus (BN) and Braford (BO) sires to produce a second generation (G₂) of progeny. Data were analyzed to estimate breed group means, individual and maternal breed additive effects, and heterosis effects on birth weight, weaning weight, preweaning average daily gain, yearling weight, postweaning average daily gain, fattening phase initial weight (around 19 mo), final weight (around 24 mo), average daily gain in the fattening phase, and age at slaughter. In general, crossbred calves outperformed purebred calves. Angus-N and CA crossbred cows weaned heavier calves. Individual taurine-indicine heterosis (Z) significantly increased weaning weight. The AN, NA, and CA steers were heaviest at yearling, whereas NA, CA, AN, and HA had the greatest final weights. However, AH steers were 1 mo older at slaughter than NA contemporaries. Taurine breed effects on postweaning traits and final weight were greater than for N. Maternal breed effects on birth weight and average daily gain in the fattening phase were greater for A and H than for N. In conclusion, heterosis effects were sufficiently large for use of N to be recommended as a component of such systems, despite their relatively low-breed additive effects compared with taurine breeds. Moreover, germplasm from the tropically adapted Bos taurus C may be particularly useful when increased milk production is desired. With the breed and heterosis effects derived in the present study, it is possible to predict the performance and infer which breed and breed crosses will perform better in crossbreeding systems designed for the subtropical conditions of southern Brazil and similar regions.

The aim of this study was to evaluate the influence of two sub-periods of the calving season and two cow maturity stages on the efficiency of beef cows and their calves. A total of 159 cow-calf pairs were divided by calving time (early or late) within the calving season and maturity stage (young or adult). Calves were weaned at 42 or 63 days after birth and evaluated until 210 days of age. Cows and calves had their development examined based on their weight and body condition score at calving, at weaning, and at 210 days. Reproductive performance was evaluated on the basis of time to become pregnant again. Milk yield was assessed by the direct method on three occasions spaced 21 days apart. Adult cows were heavier than young cows, at calving (398.5 vs 327.5 kg, respectively), weaning (397.3 vs 324.1 kg, respectively) at the end breeding season (424.1 vs 342.1 kg, respectively). Reproductive performance was influenced by calving time. Adult cows had higher pregnancy rates (83.75 and 69.17%, for early and for late calving, respectively) than young cows (57.03 and 35.01% for early and for late-calving, respectively). Calves from early-calving young cows weighed 158.8 kg at 210 days of age vs. 123.7 kg for those born from late-calving adult cows. However, late-calving cows produced 10.7% more milk than those that calved early in the season (227.0 vs 205.0 liters, respectively). Early calving associated with non-requirement of growth determine higher productivity efficiency in beef cows.

This study evaluated body development and reproductive performance of beef cows whose calves were submitted to early weaning (76 days of age), or conventional weaning (148 days of age). It was used 141 Braford cows that calved in 2004, 2005, and 2006 to evaluate weight at calving at 76 days, weight at calving at 148 days, weight at the beginning and end of the breeding season, variation of the average daily weight, body condition, pregnancy rate, and calving interval. Dams of calves weaned at 148 days of age showed daily weight gain higher body weight and better body condition at 148 days of age. The weights at the end of breeding season and average weight gain during the breeding season were higher in early weaning cows than in conventional cows. Pregnancy rate of early weaning cows (86.34%) was higher than those submitted to weaning at conventional age (55.45%). Pasture interval was similar among early weaning cows and conventional weaning cows. The best benefit on reducing weaning age in pregnancy rate was in primiparous cows. There was significant interaction between weaning age and the year for calving interval and milk production. The early weaning of calves carried out at 76 days of age allows cows to better weight recovery in the post-weaning and breeding periods, improving their body condition and consequently increasing pregnancy rate regarding to cows whose calves suckled until 148 days of age.

Objetivou-se avaliar os efeitos de diferentes sistemas de alimentação com amendoim forrageiro (Arachis pintoi) sobre o desempenho e parasitismo de borregas Corriedale. Foram avaliados três sistemas de alimentação em pastejo contínuo com ajuste de carga: 1- animais mantidos exclusivamente em campo nativo; 2- animais mantidos em campo nativo e duas horas diárias de acesso a pastagem de amendoim forrageiro; 3- animais mantidos exclusivamente em pastagem de amendoim forrageiro. Os animais foram distribuídos em delineamento completamente casualizado com dez repetições. Foram mensurados: peso médio, índice de massa corporal, escore de condição corporal, nível de anemia pelo método Famacha©, nível de hematócrito e contagem de ovos por grama de fezes. Os sistemas de alimentação, graus de infestação parasitária e sua interação foram comparados, em dois anos experimentais, através de análise de variância, teste de Fisher e teste não paramétrico de Kruskall-Wallis. A infestação parasitária foi menor no primeiro ano, 2018, independentemente do sistema de alimentação. Os sistemas de alimentação com uso de amendoim forrageiro apresentaram desempenho animal superior e menor infestação parasitária das borregas. O uso de amendoim forrageiro sob pastejo pode ser uma ferramenta no controle estratégico da verminose em borregas, desde que integrado a outros métodos de controle parasitário. Devido as condições climáticas a infestação parasitária foi diferente nos dois anos experimentais, independentemente dos sistemas de alimentação, o que pode ser uma limitação do estudo.

It was aimed in this work to evaluate the productivity and efficiency of beef cows submitted to weaning of their calves at 76 days (early weaning) or at 148 days (weaning at conventional age) after calving during three consecutive years. It was evaluated pregnancy rate, birth and weaning, gain weight of the calves and cows at conventional weaning, weight at conventional weaning of calves and cows, production of weaned calves per cow and calf production index. Pregnancy rate in the herd submitted to early weaning (86.34%) was higher than in the conventional weaning (55.5%). Early weaning cows showed higher birth and weaning rates when compared to conventional weaning (83.6 and 83.6% vs. 47.5 and 44.5%, respectively) besides a higher production of calves (183 vs. 114). Early weaning cows produced 60.5% more calves than the conventional weaning cows. Conventional weaning calves gained more weight from birth to weaning (97.9 vs. 83.4 kg, respectively). Early weaning cows had more weight gain from calving to weaning (42.5 vs. 18.7 kg, respectively), and regarded to calf production index, they were more efficient (efficiency of the herds). At the average of the three years, the early weaning of the calves allows higher calving rates and weaning to the cows, in addition to a higher index of calf kilogram index produced in relation to weaning at conventional age.