Berry D P, Friggens N C, Lucy M, Roche J R
Animal & Grassland Research and Innovation Center, Teagasc, Moorepark, County Cork, Ireland; email:
INRA and.
Annu Rev Anim Biosci. 2016;4:269-90. doi: 10.1146/annurev-animal-021815-111406. Epub 2015 Nov 2.
Evolutionary biology provides reasons for why the intensive selection for milk production reduces reproductive success rates. There is considerable exploitable genetic variation in reproductive performance in both dairy and beef cattle, and examination of national genetic trends demonstrates that genetic gain for both reproductive performance and milk production is possible in a well-structured breeding program. Reproductive failure is often postulated to be a consequence of the greater negative energy balance associated with the genetic selection for increased milk production. However, experimental results indicate that the majority of the decline in reproductive performance cannot be attributed to early lactation energy balance, per se; reproductive success will, therefore, not be greatly improved by nutritional interventions aimed at reducing the extent of negative energy balance. Modeling can aid in better pinpointing the key physiological components governing reproductive success and, also, the impact of individual improvements on overall fertility, helping to prioritize variables for inclusion in breeding programs.
进化生物学解释了为何对产奶量的高强度选择会降低繁殖成功率。奶牛和肉牛在繁殖性能方面都存在大量可利用的遗传变异，对全国遗传趋势的研究表明，在一个结构完善的育种计划中，实现繁殖性能和产奶量的遗传进展是可能的。繁殖失败通常被认为是由于为提高产奶量而进行的遗传选择导致负能量平衡加剧的结果。然而，实验结果表明，繁殖性能下降的主要原因并非早期泌乳能量平衡本身；因此，旨在减少负能量平衡程度的营养干预措施并不能显著提高繁殖成功率。建模有助于更精准地确定影响繁殖成功的关键生理因素，以及个体改良对整体繁殖力的影响，从而有助于确定育种计划中应优先考虑的变量。
