Allocation of feed based on individual dairy cow live weight changes I: Feed intake and live weight changes during lactation

摘要

Based on individual cow live weight changes, feeding strategies were designed for individual feeding of dairy cows in loose-housing systems and examined in a four-year production trial including 115 Danish Red (DR), 91 Danish Holstein (DH) and 93 Danish Jersey (DJ). Cows were kept in a dairy system based on automatic milking (AMS). The objective was to examine the relationship between feed intake and live weight changes in response to the three feeding strategies examined. All cows were allowed a combination of a mixed ration (MR) and individually separately offered concentrate (ISC) in the AMS. Cows were randomly assigned to one of three feeding strategies; MR1, MR2-E or MR2-L. Cows fed according to the MR1 strategy were allowed one medium energy ration during the whole lactation. Cows on the MR2 strategies were allowed a high energy ration during early lactation, followed by an early (MR2-E) or late (MR2-L) change to a low energy ration. The early and late change was defined as a live weight gain after live weight minimum of 15 and 35kg respectively for DR/DH and 11 and 25kg respectively for DJ. Peak energy intake obtained by primiparous cows and cows of DJ was not significantly higher in response to feeding the MR2 strategies. Early reduction (MR2-E strategy) caused a significant longer duration of the total period of mobilization compared to late reduction (MR2-L) within multiparous DR and DH cows. It indicates that early reduction of ration energy concentration forced these cows into a second period of mobilization, whereas cows continued to gain live weight in response to late reduction of ration energy concentration. In general results from the present experiment indicate that feeding according to live weight can be used to manipulate the extent and the duration of the mobilization period especially within multiparous cows. The different results obtained in response to early and late reduction of ration energy concentration suggest that transition from mobilization to deposition conditions is a reversible process only as long as cows are not fully adapted to deposition metabolism. Additionally the results suggest that the transition period from mobilization to deposition is relatively short.