Department of Animal Science, Federal University of Pelotas, Pelotas - Rio Grande do Sul, Brazil.
Delta G, Miles City, Montana, MT.
J Anim Sci. 2018 Jun 29;96(7):2536-2544. doi: 10.1093/jas/sky160.
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.
本研究的目的是比较在巴西南里奥格兰德州饲养的不同品种组从出生到屠宰的生长情况，并估计由此产生的品种加性和杂种优势效应。卡拉库（C）、海弗福德（H）和内罗尔（N）的公牛与安格斯（A）的母牛交配，A 的公牛与 H 和 N 的母牛交配，产生第一代杂交后代，与纯种的 A、H 和 N 小牛同期。第一代（G1）的小母牛与布郎格斯（BN）和布拉福（BO）的公牛交配，产生第二代（G2）的后代。对数据进行了分析，以估计品种组平均值、个体和母本品种加性效应以及初生重、断奶重、断奶前平均日增重、1 岁重、断奶后平均日增重、育肥期初始体重（约 19 月龄）、最终体重（约 24 月龄）、育肥期平均日增重和屠宰年龄的杂种优势效应。一般来说，杂交牛犊的表现优于纯种牛犊。安格斯-N 和 CA 杂交母牛断奶的小牛体重较重。个体 Taurine-indicine 杂种优势（Z）显著增加了断奶重。AN、NA 和 CA 阉牛在 1 岁时最重，而 NA、CA、AN 和 HA 具有最大的最终体重。然而，AH 阉牛比同期的 NA 晚 1 个月屠宰。Taurine 品种对断奶后性状和最终体重的影响大于 N。母本品种对初生重和育肥期平均日增重的影响大于 A 和 H。综上所述，尽管与 Taurine 品种相比，N 的品种加性效应相对较低，但杂种优势效应足够大，值得推荐作为此类系统的组成部分。此外，当需要增加牛奶产量时，来自热带适应的 Bos taurus C 的种质可能特别有用。利用本研究中获得的品种和杂种优势效应，可以预测性能，并推断哪些品种和品种杂交在为巴西南部和类似地区的亚热带条件设计的杂交系统中表现更好。
