Burke C R, Verkerk G A
DairyNZ Limited, Private Bag 3221, Hamilton 3240, New Zealand.
Soc Reprod Fertil Suppl. 2010;67:341-55. doi: 10.7313/upo9781907284991.027.
The New Zealand (NZ) economy and its dairy industry are sensitive to global consumer perception of farming practices used to generate milk products because milk exports account for > 25% of national export earnings and > 90% of milk produced is exported as products. Astute management of product image and market risk is, therefore, important for the viability of the industry and country. More than 95% of milk produced in NZ comes from strictly seasonal, pasture-based systems, with associated constraints on reproductive performance. Increasing herd sizes, operational changes and genetic selection priorities have further challenged dairy farmers to achieve optimal levels of herd fertility. Reproductive management practices have developed to address the need to maintain a 365-day inter-calving interval, essentially through maximizing the number of cyclic cows during the breeding period and minimizing the duration of the seasonal calving period. Aspects of the hormonal interventions developed and routinely used to achieve these objectives have been the subject of product quality and market risk concerns forcing the industry to explore alternative ways of achieving reproductive performance goals. One approach has been to exploit the inherently high level of fertility in NZ dairy herds. This approach has seen the inclusion of fertility-related traits in the national genetic evaluation system to prevent further decline in genetic fertility. More recently, a nationally coordinated extension program has been adopted to support farmers and their advisors to identify, prioritize and improve on key management areas for incremental gains in herd reproductive performance. Advances in automation and bio-sensing are yet to make a significant impact, but remain potentially valuable additions in supporting the dairy farmer to manage the areas having the largest effects on reproductive performance.
新西兰经济及其乳制品行业对全球消费者对用于生产乳制品的养殖方式的认知较为敏感，因为牛奶出口占国家出口收入的25%以上，且所产牛奶的90%以上作为产品出口。因此，精明地管理产品形象和市场风险对该行业乃至国家的生存能力至关重要。新西兰生产的牛奶超过95%来自严格季节性的、以牧场为基础的养殖系统，这对繁殖性能存在相关限制。牛群规模的扩大、运营变化以及遗传选择重点的改变，进一步促使奶农实现最佳的牛群繁殖力水平。繁殖管理措施的发展旨在满足维持365天产犊间隔的需求，主要是通过在繁殖期最大化周期性发情母牛的数量，并缩短季节性产犊期的时长来实现。为实现这些目标而研发并常规使用的激素干预措施的某些方面，一直是产品质量和市场风险担忧的主题，这迫使该行业探索实现繁殖性能目标的替代方法。一种方法是利用新西兰奶牛群固有的高繁殖力水平。这种方法已将与繁殖力相关的性状纳入国家遗传评估系统，以防止遗传繁殖力进一步下降。最近，已采用一项全国协调的推广计划，以支持奶农及其顾问确定、优先考虑并改进关键管理领域，从而逐步提高牛群繁殖性能。自动化和生物传感方面的进展尚未产生重大影响，但在支持奶农管理对繁殖性能影响最大的领域方面仍可能具有宝贵价值。
