Growth of modern Guernsey and Jersey dairy heifers was appraised. Height at withers and heart girth (BW) data were collected from 1777 Guernsey heifers representing 54 commercial dairy herds and 1564 Jersey heifers representing 49 commercial dairy herds from 1984 through 1987. Means and SD for height and weight were determined for each age (1 through 24 mo) within breed. Third-order regressions on age were fitted to the means to describe height and weight within breed. Subsets of data from herds with above average production were analyzed separately. Means of heifers in 24 Guernsey herds that had a herd average milk production greater than 5822 kg and 25 Jersey herds that had a herd average milk production p t e r than 5515 kg were fitted. Weights of heifers in these subsets were moderately heavier than those in the entire data sets of the respective breeds, although heights were similar. Based on the entire data set, commercial Guernsey herds today contain replacement heifers heavier and taller than those previously reported, but Jersey heifers are similar to those previously reported.
All Science Journal Classification (ASJC) codes
- Food Science
- Animal Science and Zoology