CRC for Sheep Industry Innovation and University of New England, Armidale, New South Wales, Australia.
Theriogenology. 2013 Sep 15;80(5):427-35. doi: 10.1016/j.theriogenology.2013.05.004. Epub 2013 Jun 10.
We studied the relationships among growth, body composition and reproductive performance in ewe lambs with known phenotypic values for depth of eye muscle (EMD) and fat (FAT) and Australian Sheep Breeding Values for post-weaning live weight (PWT) and depth of eye muscle (PEMD) and fat (PFAT). To detect estrus, vasectomized rams were placed with 190 Merino ewe lambs when on average they were 157 days old. The vasectomized rams were replaced with entire rams when the ewe lambs were, on average, 226 days old. Lambs were weighed every week and blood was sampled on four occasions for assay of ghrelin, leptin and ß-hydroxybutyrate. Almost 90% of the lambs attained puberty during the experiment, at an average live weight of 41.4 kg and average age of 197 days. Ewe lambs with higher values for EMD (P < 0.001), FAT (P < 0.01), PWT (P < 0.001), PEMD (P < 0.05) and PFAT (P < 0.05) were more likely to achieve puberty by 251 days of age. Thirty-six percent of the lambs conceived and, at the estimated date of conception, the average live weight was 46.9 ± 0.6 kg and average age was 273 days. Fertility, fecundity and reproductive rate were positively related to PWT (P < 0.05) and thus live weight at the start of mating (P < 0.001). Reproductive performance was not correlated with blood concentrations of ghrelin, leptin or ß-hydroxybutyrate. Many ewe lambs attained puberty, as detected by vasectomized rams, but then failed to become pregnant after mating with entire rams. Nevertheless, we can conclude that in ewe lambs mated at 8 months of age, higher breeding values for growth, muscle and fat are positively correlated with reproductive performance, although the effects of breeding values and responses to live weight are highly variable.
我们研究了具有已知眼肌深度（EMD）和脂肪（FAT）表型值以及澳大利亚绵羊育肥后活重（PWT）和眼肌深度（PEMD）和脂肪（PFAT）的绵羊繁殖性能的生长、身体成分和繁殖性能之间的关系。为了检测发情，当平均年龄为 157 天时，将去势公羊与 190 只美利奴母羊一起放置。当母羊平均年龄为 226 天时，用整只公羊替换去势公羊。每周给羔羊称重，并在四个时间点采集血液，用于测定生长激素释放肽、瘦素和β-羟丁酸。在实验过程中，几乎 90%的羔羊在平均活重为 41.4 公斤和平均年龄为 197 天时达到性成熟。眼肌深度（P < 0.001）、脂肪（P < 0.01）、PWT（P < 0.001）、PEMD（P < 0.05）和 PFAT（P < 0.05）值较高的母羊更有可能在 251 天龄时达到性成熟。36%的羔羊受孕，在估计的受孕日期，平均活重为 46.9±0.6 公斤，平均年龄为 273 天。繁殖力、繁殖力和繁殖率与 PWT（P < 0.05）和配种时的体重（P < 0.001）呈正相关。繁殖性能与生长激素释放肽、瘦素或β-羟丁酸的血液浓度无关。许多母羊通过去势公羊检测到性成熟，但在与整只公羊交配后未能怀孕。尽管如此，我们可以得出结论，在 8 个月大的母羊中，生长、肌肉和脂肪的更高繁殖值与繁殖性能呈正相关，尽管繁殖值和对体重的反应的影响高度可变。
