Relationships between early life growth and first lactation performance of Holstein dairy cows

Abstract Text: The objective was to determine relationships between early life ADG and BW and first lactation performance of Holstein cows. Data were collected from birth yr of 2004 to 2012 for 2,880 Holstein animals. Calves were received from 3 commercial dairy farms and enrolled in 37 different calf research trials at SROC from 3 to 195 d. Upon trial completion, calves were returned to their respective farms. Milk replacer options included varying protein level and amounts fed but in the majority of studies calves were fed a 20% CP: 20% fat MR at 0.57 kg/calf daily. Most calves (93%) were weaned at 6 wk. Milk replacer DM 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.  Average age at first calving and first lactation 305-d milk yield were: 715 ± 46.5 d and 10959 ± 1527 kg, respectively. Separate mixed model analyses were conducted using the REML model fitting protocol of JMP (SAS) to determine the effect of 6 wk BW or ADG on first-lactation 305-d milk, fat, and true protein yield. Birth season and calving season, yr, and yr nested within herd were included in the models with calf trial as a random effect. Early life BW and ADG positively affected first-lactation 305-d yield of milk and components (P < 0.03; Table 1). Six-week ADG class (< 0.23, 0.23-0.33, 0.34-0.44, 0.45-0.56, 0.57-0.67, 0.68-0.80, and > 0.80 kg/d) also affected 305-d yield of milk and components (P < 0.02).  Greater BW and ADG at 6 wk resulted in increased first lactation milk and milk component yields. However, these improvements were modest and variation was high suggesting additional factors not accounted for in this analysis impact first lactation performance.

Keywords: calves, early life, growth, first lactation