Relationships between Early-Life Growth and Protein and Energy Intake with First-Lactation Performance of Holstein Dairy Cows.

The objective was to determine the relationships between early-life growth parameters, milk replacer protein and ME intake, starter protein and ME intake, and the first-lactation performance of Holstein cows. We collected data from birth years 2004 to 2014 for 4,534 Holstein animals. Calves were received from 3 commercial dairy farms and enrolled in 42 different calf research trials at the University of Minnesota Southern Research and Outreach Center from 3 to 195 d. Upon trial completion, calves were returned to their respective farms. Milk replacer options included varying protein levels and amounts fed, but in the majority of studies, calves were fed a milk replacer containing 20% crude protein and 20% fat at 0.57 kg/calf daily. Most calves were weaned at 6 wk. Milk replacer dry matter intake, starter intake, ADG, and BW at 6 wk were 21.5 ± 2.2 kg, 17.3 ± 7.3 kg, 0.53 ± 0.13 kg/d, and 62.4 ± 6.8 kg, respectively. Mixed-model analyses were used to determine the effect of early-life ADG, milk replacer and starter protein and ME intake, and birth season on first-lactation 305-d milk, fat, and true protein yield. Milk replacer ME, starter ME, milk replacer protein intake, and starter intake consumed from 0-8 weeks were (mean ± SD): 102.7 ± 13.2 Mcal/kg, 151.0 ± 42.2 Mcal/kg, 4.8 ± 1.0 kg, and 9.5 ± 2.7 kg, respectively. Calves that had greater intake of protein during the first 8 weeks of life resulted in greater growth. Greater ADG at 6 wk resulted in increased first-lactation milk and milk component yields. Intake of calf starter at 8 wk had a significant positive relationship with first-lactation 305-d yield of milk and milk components. The 305-d milk and component production were positively affected by early life ME and protein intake. Greater ME and protein intake in the first 8 weeks of life resulted in increased first lactation milk and milk components yield. Calves born in the fall and winter had greater starter intake and ADG at 8 wk. Variation was high in all estimates suggesting additional factors affect first lactation milk production.