The effect of protein-feeding strategy during lactation on performance of primiparous dairy cows fed total mixed ration

The average daily milk yield (cCP: 26.3 kg/day vs. vCP: 27.5 kg/day) was higher (P<0.05) when feeding concentrate with decreasing protein content, but the effect was not seen in an energy-corrected milk (cCP: 28.1 kg/day vs. vCP: 29.0 kg/day). Milk composition was not affected by the protein-feeding strategy. Protein-feeding strategy had no effect on DM intake (cCP: 18.5 kg/day vs. vCP: 18.9 kg/day). The efficiency of CP utilization (milk protein/CP intake) was higher (0.327 vs. 0.301; P<0.05) on vCP treatment during the last 100 days of lactation, but during the first 200 days of lactation, no significant difference was found. The average efficiency of CP utilization throughout the lactation was 0.32 with no difference between treatments. The protein-feeding strategy had no effect on the development of body condition scores of the cows. In mid-lactation, the cows on cCP treatment gained more weight than the cows on vCP treatment. The health product had no significant effect on production or feed intake. The results suggest that only small benefits can be obtained from feeding TMR to primiparous cows differing in CP content at various stages of lactation.