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Mature cow body weight associations with calf growth and feed intake traits
The purpose of this study was to understand the association between heifer calf growth and feed intake traits with cow mature body weight. Data was collected for Holstein heifer calves from six different calf trials of varying lengths conducted at Pennsylvania State University between 2003 and 2010. Measurements of calf hip height, starter feed intake, and body weight were collected for periods ranging from 4 to 8 weeks after birth. Resulting data was divided into high, medium, and low ranking groups according to calf hip height, starter feed intake, body weight, and growth rate. Calf growth data was merged with 37,403 mature body weight records from 75 cows taken from lactations 1, 2, and 3. Mixed model equations methods were used to evaluate the data. Lactation, days in milk, treatment within trial, calf groups, and lactation by days in milk were fitted as fixed effects while cow, cow by lactation, and calendar week by year were included as random effects. Cows from the low growth rate classification as calves were significantly (P < 0.01) lighter as mature cows, weighing 45.3 ± 14.70 kg and 52.7 ± 14.44 kg less than cows from the intermediate and high growth rate calf classifications, respectively. In the same manner, cows from the low starter intake classification as calves were significantly (P < 0.01) lighter as mature cows, weighing 47.2 ± 15.37 kg and 47.1 ± 15.11 kg less than cows from the intermediate and high starter intake calf classifications, respectively. No mature body weight differences were observed for cows that differed for hip height or body weight as calves (P > 0.10). Results from this study suggest that low growth rate and starter feed intake in calves could be indicative of future low mature cow body weight.
Keywords:
Body Weight, Feed Intake, Growth Rate