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1235
Relationships between early life milk replacer and starter intake and first lactation performance of Holstein dairy cows
The objective was to determine relationships between early life milk replacer and starter intake 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 8 wk were (mean ± SD): 21.7 ± 2.5, 44.4 ± 12.0 kg, 0.63 ± 0.12 kg/d, and 75.8 ± 8.4 kg, respectively. Average age at first calving and first lactation 305-d milk yield were: 715 ± 46.5 d and 10959 ± 1527 kg, respectively. Mixed model analysis was conducted using the REML model fitting protocol of JMP (SAS) to determine the effect of 8 wk milk replacer and 8 wk calf starter intake on first-lactation 305-d milk, milk fat, and true protein yield. Birth season, calving season, calving yr, and calving yr nested within herd were included in the models with calf trial as a random effect. Eight-wk intake of calf starter had a significant positive effect on first lactation 305-d yield of milk and milk components (P < 0.01; Table 1). However, these improvements were modest and variation was high suggesting additional factors not accounted for in this analysis impact first lactation performance. Milk replacer intake, which varied very little in this dataset, had no effect on first lactation 305-d yield of milk and milk components.
Keywords: calves, milk replacer, calf starter, first lactation.