Abstract/Summary

The objective was to determine the effects of a daily rumen drench of maize gluten meal, as a source of rumen undegradable protein (RUP), and rumen protected Met, Lys, and His for the first 4 days of lactation on DMI and milk production and composition of dairy cows during their first 12 weeks of lactation. Twenty multi-parous Holstein cows were randomly assigned at calving to a control rumen drench of 30 L warm water or a 30 L aqueous suspension of maize gluten meal and rumen-protected Met, Lys, and His calculated to provide Met, Lys, His, and Leu for absorption equal to their amounts in 600 g casein. Cows received their first drench within 8 h of calving and then again 24, 48, and 72 h later. Cows were fed a TMR for ad libitum consumption and at 7 DIM cows were moved from calving boxes to a cubicle yard, and measurements of daily DMI and milk yield and weekly milk composition, BW, and body condition score (BCS) were obtained through week 12 postpartum. A blood plasma sample obtained at 7 DIM was analysed for metabolite, protein and albumin concentration. There was no effect of treatment on DMI or milk yield, but milk fat concentration was higher and milk protein concentration tended to be higher for treated cows during weeks 2 to 12. Whilst BCS was not affected, treated cows gained BW over the course of the study (+32 kg), whereas control cows maintained a similar body weight (-3 kg). Plasma metabolite and protein concentrations were not affected by treatment. Four daily rumen doses of supplemental RUP and rumen protected EAA, initiated within hours of calving, had sustained positive effects on milk fat and protein concentration and BW of lactating Holstein cows, suggesting homeorhetic effects that warrant further investigation.