Genetic evaluation of milking buffaloes (Bubalus bubalis): bull ranking

ABSTRACT The objective of this study was to evaluate genetic aspects related to production and reproductive efficiency of Murrah and Mediterranean buffaloes and their crosses. A ranking of bulls from Embrapa Eastern Amazonia was also composed to guide assisted mating. Birth records of 2,322 Murrah, Mediterranean, and crossbred buffaloes from the Embrapa Eastern Amazon herd, from 1953 to 2013, as well as information on production and reproductive traits were used. Genetic analyzes were performed in the WOMBAT software using the animal model with two-trait analysis. While heritability (h2) for total milk production (TMP) and fat milk percentage (F) were generally high, for reproductive traits h2 tended to be low. Genetic correlations for TMP with the other traits were low and negative, except for TMP with calving interval (CI) and service period (SP) in the Mediterranean breed and with age at first calving (AFC) and SP in crossbred, which were positive and high. Bull 1001 had high predicted transmitting ability (PTA) for TMP, so it should transmit a greater volume of milk to his offspring, although it had a lower PTA for F. There was sufficient variability within the herd to work with genetic management for both production and reproductive efficiency.摘要 本研究旨在评估摩拉水牛（Murrah）、地中海水牛（Mediterranean）及其杂交群体的生产与繁殖效率相关遗传性状。同时构建了来自东亚马逊巴西农牧业研究公司（Embrapa Eastern Amazonia）的种公牛排名，以指导辅助配种工作。本研究采用了1953年至2013年间该公司牛群中2322头摩拉水牛、地中海水牛及其杂交后代的出生记录，以及生产与繁殖性状的相关数据。研究采用两性状分析的动物模型，借助WOMBAT软件完成遗传评估分析。结果表明，总产奶量（total milk production, TMP）与乳脂率（fat milk percentage, F）的遗传力（h²）普遍处于较高水平，而繁殖性状的遗传力则普遍偏低。总产奶量与其余多数性状的遗传相关系数呈低水平负值，但在地中海水牛群体中，总产奶量与产犊间隔（calving interval, CI）、配种间隔（service period, SP）呈显著正相关；在杂交水牛群体中，总产奶量与首产犊年龄（age at first calving, AFC）及配种间隔同样呈显著正相关。种公牛1001的总产奶量预期传递力（predicted transmitting ability, PTA）较高，意味着其后代可获得更高的产奶量遗传潜力，尽管该公牛的乳脂率预期传递力相对较低。该牛群内存在充足的遗传变异，可用于开展兼顾生产与繁殖效率的遗传管理工作。