Adaptation Physiology group, Wageningen University & Research,Wageningen,The Netherlands.
College of Animal Science and Technology, Southwest University,Chongqing,P. R. China.
Animal. 2019 Jul;13(S1):s42-s51. doi: 10.1017/S1751731119001174.
Shortening or omitting the dry period improves the energy balance and metabolic status of dairy cows in early lactation. Metabolic, behaviour and welfare effects throughout lactation, however, are unclear. The current paper reviews long-term metabolic and welfare consequences of short and no dry period, as well as feeding strategies and individual cow characteristics that could support in optimising management of cows with a short or no dry period. The paper will conclude with impacts of short and no dry periods at herd level and in practice. Energy balance after no or a short dry period is more positive during the complete subsequent lactation. After the initial improvement in early lactation, cows after no dry period tend to fatten and may have a too low lactation persistency to be continuously milked until the onset of the subsequent lactation. Reducing dietary energy level for cows with no dry period reduced fattening during the complete lactation but did not improve lactation persistency. Feeding a more lipogenic diet for cows with a short or no dry period did not affect the energy balance or lactation persistency during the complete lactation, although a lipogenic diet resulted in lower plasma insulin and IGF-1 concentration and greater plasma growth hormone concentration, compared with a glucogenic diet. Effects of dry period length on udder health are ambiguous, whereas short and no dry periods improved fertility in most studies. Omission of the dry period changed behaviour of cows both before and after calving, with a longer lying time and greater feed intake after calving, suggesting a better adaptation to a new lactation. Individual cow characteristics like parity, genotype, prepartum body condition score, and milk yield level determined the metabolic response of cows to a short or no dry period. In conclusion, short or no dry periods increase the energy balance in the complete lactation. Feeding strategies can be used to limit fattening of cows with no or short dry period, but the studied feeding strategies did not increase lactation persistency. Improved fertility and behavioural changes around calving suggest a better adaptation to a new lactation in case of no dry period. Customised dry period lengths for individual cows could improve metabolic status of cows at risk of a severe negative energy balance while minimising milk losses.
缩短或取消干奶期可以改善奶牛在泌乳早期的能量平衡和代谢状况。然而，整个泌乳期的代谢、行为和福利影响尚不清楚。本文综述了短干奶期和无干奶期的长期代谢和福利后果，以及可以支持优化管理短干奶期或无干奶期奶牛的饲养策略和个体牛特征。本文将以短干奶期和无干奶期对牛群和实践的影响结束。无干奶期或短干奶期后，整个泌乳期的能量平衡更为积极。在早期泌乳期的最初改善后，无干奶期奶牛往往会增肥，并且可能由于泌乳持续性太低而无法持续挤奶直到下一个泌乳期开始。对于无干奶期奶牛，降低日粮能量水平可减少整个泌乳期的增肥，但并未提高泌乳持续性。对于短干奶期或无干奶期奶牛，饲喂更具生脂特性的日粮并未影响整个泌乳期的能量平衡或泌乳持续性，尽管与生糖日粮相比，生脂日粮会导致较低的血浆胰岛素和 IGF-1 浓度和较高的血浆生长激素浓度。干奶期长短对乳房健康的影响尚不清楚，而短干奶期和无干奶期在大多数研究中提高了奶牛的繁殖力。取消干奶期改变了奶牛在产犊前后的行为，产犊后躺卧时间延长，采食量增加，表明对新泌乳期的适应更好。个体牛特征如胎次、基因型、产前体况评分和产奶量水平决定了奶牛对短干奶期或无干奶期的代谢反应。总之，短干奶期或无干奶期增加了整个泌乳期的能量平衡。可以使用饲养策略来限制无干奶期或短干奶期奶牛的增肥，但所研究的饲养策略并未提高泌乳持续性。发情前后行为的改善表明，在无干奶期时，奶牛对新泌乳期的适应更好。针对个体牛的个性化干奶期长度可以改善处于严重负能量平衡风险的奶牛的代谢状况，同时最大限度地减少产奶量损失。
