The effect of pre-calving diet on post-calving cow performance

There are a number of inter-related management factors during the dry period, including nutrition, which influence milk production in the subsequent lactation. The objective of this experiment was to investigate the influence of two diets, differing widely in energy density, fed for 5 weeks before calving, on subsequent early lactation performance. Fifty-six spring-calving Holstein Friesian dairy cows were separated into two groups on the basis of lactation number (lactation number two or lactation number three and greater) blocked into pairs within these groups and from within pairs randomly assigned to two treatments, 9 weeks from expected parturition date. The pre-calving experimental treatments were: Treatment A––grass silage ad-libitum with 3 kg/cow per day of concentrates offered 5 weeks from expected parturition date and Treatment B––grass silage/straw mixture (75/25 on a DM basis) ad-libitum. A diet consisting of grass silage ad-libitum plus 8 kg/cow per day of concentrates was fed to all cows post-calving and cow performance was measured for 8 weeks post-calving. The silage and straw were of good quality (in-vitro dry matter digestibilities of 731 and 597 g/kg, respectively). The body condition score at calving was significantly higher (P<0.05) for Treatment A (3.0) than for Treatment B (2.73). There was no difference in liveweight at calving. The cows on Treatment A had a significantly higher milk yield (P<0.05) for the first 4 weeks of lactation. There was no significant difference in fat yield but milk protein yield (1.01 and 0.93 kg/cow per day) (P <0.001) and milk lactose yield (1.17 and 1.10 kg/cow per day) (P<0.05) were higher on Treatment A than Treatment B. There were no significant differences between the treatments in the concentrations of fat, protein and lactose. Also, treatment had no significant effect on dry matter intake, (Treatment A 15.0 kg/head and Treatment B 15.2 kg/head), body condition score loss and bodyweight loss post-calving.