Priming the dairy cow for lactation: a review of dry cow feeding strategies

This paper reviews important aspects of dry cow feeding with emphasis placed on the preparation of the cow for the subsequent lactation. A number of feeding strategies, which have been proposed in recent years, are examined, alongside considerations of the effects of dry period length, levels of body reserves at calving and parity. A number of studies have reported the effect of varying the length of the dry period (in the range 0 to 70 days) on subsequent production and health. An 8 week dry period seems optimal though this should be adjusted to allow for the body condition score of cows at drying off. Avoiding extremes of body condition score at calving is desirable, so condition should be monitored throughout the lactation cycle. Attempting to achieve large changes in body reserves in the dry period has been associated with increased problems postpartum. The feeding strategies that are reviewed are strategies to decrease body mobilisation, prime for body mobilisation, prime the rumen for increased intake, prime for milk protein production and prime for calcium mobilisation and absorption. These strategies are also evaluated relative to their biological basis and reported physiological effects. Feeding high starch feeds in the latter part of the dry period was found not to provide clear benefits in terms of decreasing early lactation body mobilisation or increasing early lactation intake. Strategies aimed at priming the cow for the increased mobilisation of body lipid and body calcium that occurs in early lactation appear more favourable both from the point of view of making biological sense and from the available results reviewed.