Price Tanner P, Souza Vinícius C, Liebe Douglas M, Elett Mark D, Davis Ty C, Gleason Claire B, Daniels Kristy M, White Robin R
Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Department of Dairy Science, Virginia Tech, Blacksburg, VA 24061, USA.
Animals (Basel). 2021 Dec 10;11(12):3518. doi: 10.3390/ani11123518.
Immediate and short-term changes in diet composition can support individualized, real-time interventions in precision dairy production systems, and might increase feed efficiency (FE) of dairy cattle in the short-term. The objective of this study was to determine immediate and short-term effects of changes in diet composition on production parameters of dairy cattle fed varying amounts of top dressed commodities. A 4 × 4 replicated Latin square design was used to evaluate responses of twenty-four Holstein cows fed either no top dress (Control) or increasing amounts of: corn grain (CG), soybean meal (SBM), or chopped mixed grass hay (GH) top dressed on a total mixed ration (TMR) over four, 9-day periods. Throughout each period, top dressed commodities were incrementally increased, providing 0% to 20% of calculated net energy of lactation (NE) intake. Measured production responses were analyzed for each 9-d period using a mixed-effects model considering two different time ranges. Samples collected from d 3 and 4 and from d 7 and 8 of each period were averaged and used to reflect "immediate" vs. "short-term" responses, respectively. In the immediate response time frame, control fed cows had lower milk yield, milk fat yield, and milk true protein yield than CG and SBM supplemented animals but similar responses to GH supplemented animals. Milk fat and protein percentages were not affected by top dress type in the immediate term. In the short-term response time-frame, GH supplemented animals had lower DMI and milk fat yield than all other groups. Control and GH supplemented cows had lower milk yield than CG and SBM fed cows. In the immediate response time frame, FE of SBM supplemented cows was superior to other groups. In the short-term time frame, FE of GH and SBM groups was improved over the control group. Results suggest that lactating dairy cows show rapid performance responses to small (<20% NE) changes in dietary composition, which may be leveraged within automated precision feeding systems to optimize efficiency of production. Before this potential can be realized, further research is needed to examine integration of such strategies into automatic feeding systems and downstream impacts on individual animal FE and farm profitability.
日粮组成的即时和短期变化能够支持精准奶牛生产系统中的个性化实时干预，并可能在短期内提高奶牛的饲料效率（FE）。本研究的目的是确定日粮组成变化对采食不同量的额外添加商品饲料的奶牛生产参数的即时和短期影响。采用4×4重复拉丁方设计，评估24头荷斯坦奶牛的反应，这些奶牛在四个9天周期内，分别不进行额外添加（对照组）或添加逐渐增加量的：玉米谷物（CG）、豆粕（SBM）或切碎的混合禾本科干草（GH）到全混合日粮（TMR）中。在每个周期内，额外添加的商品饲料量逐渐增加，提供泌乳净能量（NE）摄入量计算值的0%至20%。使用考虑两个不同时间范围的混合效应模型，对每个9天周期的测量生产反应进行分析。从每个周期的第3天和第4天以及第7天和第8天采集的样本进行平均，分别用于反映“即时”与“短期”反应。在即时反应时间范围内，与添加CG和SBM的动物相比，对照组奶牛的产奶量、乳脂产量和乳真蛋白产量较低，但与添加GH的动物反应相似。短期内，乳脂和蛋白质百分比不受额外添加类型的影响。在短期反应时间范围内，添加GH的动物的干物质采食量（DMI）和乳脂产量低于所有其他组。对照组和添加GH的奶牛的产奶量低于饲喂CG和SBM的奶牛。在即时反应时间范围内，添加SBM的奶牛的饲料效率优于其他组。在短期时间范围内，GH组和SBM组的饲料效率相对于对照组有所提高。结果表明泌乳奶牛对日粮组成的微小（<20%NE）变化表现出快速的生产反应，这可在自动化精准饲喂系统中加以利用，以优化生产效率。在实现这一潜力之前，需要进一步研究将此类策略整合到自动饲喂系统中以及对个体动物饲料效率和农场盈利能力的下游影响。
