Effect of dietary energy supply to dry Holstein cows with high or low body condition score at dry off on production and metabolism in early lactation

Abstract

The aim of the experiment was to investigate the effects of manipulating body condition score (BCS) during the dry period of over-conditioned and under-conditioned cows using two dry period diets with high and low energy content, respectively. The cows׳ ability to cope with the transition from pregnancy to lactation was evaluated by production parameters and several plasma and liver variables. Furthermore, the outcome of the experiment was used to see the potential of using BCS at dry off as a guiding principle in dry cow feeding management.A complete randomized design was used with a two by two factorial arrangement of treatments. Fifty-one Holstein dairy cows participated in the trial from 20 weeks before expected calving to eight weeks postpartum. With the aim to obtain two groups of cows with high or low BCS at dry off, the cows were divided into two groups in late lactation and assigned to one of two different late lactation diets: High‐energy diet (HiLate, net energy for lactation (NEL)=6.76MJ) or low-energy diet (LoLate, NEL=5.73MJ). At dry off, each group was divided and assigned to one of two dry period diets: High-energy diet (HiDry, NEL=6.86MJ) or low-energy diet (LoDry, NEL=4.96MJ). Thus, from dry off the cows were divided into four groups (HiHi, HiLo, LoHi and LoLo). After parturition, all cows received the same lactation diet (NEL=6.73MJ).Irrespective of BCS at dry off, it was demonstrated that cows fed the LoDry diet were physiologically healthier and in less risk of developing metabolic diseases in early lactation, compared to cows with the same late lactation background fed the HiDry diet. This result was established despite the fact that energy intake and milk production in early lactation was not different between the groups with the same BCS at dry off.In early lactation, there was a lower concentration of plasma non-esterified fatty acids and plasma β-hydroxybutyrate and a numeric higher concentration of plasma glucose in the HiLo group compared with the HiHi group. The difference between the LoHi group and the LoLo group showed the same trends. The milk productions in early lactation were related to the treatments in late lactation, irrespective of the dry period feeding treatments hence, implying the importance of acknowledging carry-over effects from the energy intake in the previous lactation.