Cabrera V E, Kalantari A S
Department of Dairy Science, University of Wisconsin, Madison 53706.
Department of Dairy Science, University of Wisconsin, Madison 53706.
J Dairy Sci. 2016 Jan;99(1):825-41. doi: 10.3168/jds.2015-9846. Epub 2015 Oct 29.
Nutritional grouping of lactating cows under total mixed ration (TMR) feeding systems has been discussed in the literature since 1970. Most studies have concluded that using multiple, more-homogeneous TMR feeding groups is economically beneficial because of either nutrient cost savings, improved productivity, or both. Nonetheless, no consensus has been formed around this technique nor has it been widely adopted. By using optimal criteria for grouping and more precise nutrient specifications of diets, the latest studies have reported a consistently greater income over feed cost ($/cow per year) with multiple TMR groups compared with 1 TMR (3 TMR=$46 and 2 TMR=$21 to $39). Critical factors that determine the economic value of nutritional grouping are: (1) criteria for grouping, (2) nutrient specifications of diets, (3) effects on milk production, (4) health and environmental benefits, (5) number, size, and frequency of grouping, and (6) additional costs and benefits. It has been documented that grouping cows according to their simultaneous nutritional requirements (a.k.a., cluster grouping) is optimal. Cluster grouping is superior to other methods, such as grouping according to days in milk, milk production, or production and body weight combined. However, the dairy industry still uses less-than-optimal grouping criteria. Using cluster grouping will enhance the positive economic effects of multiple TMR. In addition, nutrient specifications of diets for groups do not seem optimal either. Milk lead factors, which are only based on group average milk production, are used. Diets could, however, be formulated more precisely based on overall group nutrient requirements. Providing more precise diets should also be in favor of grouping economics. Furthermore, an area that requires more attention is the potential negative effect of grouping on the milk production of moved cows because of either or both social interactions or diet concentration changes. Although the literature is inconclusive on this subject matter, the latest studies indicate that multiple TMR groups economically outperform 1 TMR, even after considering plausible potential milk losses when grouping. Moreover, additional positive effects of nutritional grouping of improved herd health and environmental stewardship should be translated into economic benefits. Finally, additional costs of management, labor, facilities, and equipment required for grouping are farm specific. The few studies that have integrated these factors in their analyses found that multiple TMR groups would still be economically superior to 1 TMR.
自1970年以来，文献中一直在讨论全混合日粮（TMR）饲喂系统下泌乳奶牛的营养分组问题。大多数研究得出结论，采用多个更均匀的TMR饲喂组在经济上是有益的，原因在于节省了营养成本、提高了生产力，或两者兼而有之。尽管如此，围绕这项技术尚未形成共识，也未得到广泛采用。通过使用分组的最佳标准和更精确的日粮营养规格，最新研究报告称，与1个TMR组相比，多个TMR组的饲料成本收益（每年每头奶牛的美元数）始终更高（3个TMR组为46美元，2个TMR组为21至39美元）。决定营养分组经济价值的关键因素包括：（1）分组标准；（2）日粮营养规格；（3）对产奶量的影响；（4）健康和环境效益；（5）分组的数量、规模和频率；（6）额外成本和效益。有文献记载，根据奶牛同时期的营养需求进行分组（即聚类分组）是最佳方法。聚类分组优于其他方法，如按泌乳天数、产奶量或产奶量与体重相结合进行分组。然而，乳制品行业仍在使用不太理想的分组标准。采用聚类分组将增强多个TMR组带来的积极经济效应。此外，各分组日粮的营养规格似乎也不理想。目前使用的是仅基于组平均产奶量的产奶主导因子。然而，日粮可以根据整个组的营养需求更精确地配制。提供更精确的日粮也应有利于分组的经济效益。此外，一个需要更多关注的领域是分组对因社会互动或日粮浓度变化其中之一或两者导致的转群奶牛产奶量的潜在负面影响。尽管文献在这个问题上尚无定论，但最新研究表明，即使考虑分组时可能出现的合理潜在产奶量损失，多个TMR组在经济上仍优于1个TMR组。此外，可以将营养分组对改善畜群健康和环境管理的额外积极影响转化为经济效益。最后，如果进行分组，所需的管理、劳动力、设施和设备的额外成本因农场而异。少数在分析中综合考虑这些因素的研究发现，多个TMR组在经济上仍优于1个TMR组。
