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Effects of Age, Herd, and Herd Status on Classification Scores of Jersey Cattle

Department of Dairy Science, The Ohio State University, Columbus 43210
Department of Animal Science, Cornell University, Ithaca, New York 14850

ABSTRACT

Classification was arranged for herds belonging to the official Jersey program concurrently with classification for Jersey research herds. Herds were categorized as official, registered research and grade research. Cattle were also grouped as 2 year olds, 3 to 4 year olds and 5 year olds.

Differences for herd status were significant (P < .05) for all type traits except stature, breed character, feet and legs and fore udder. Research cattle scored higher only in dairy character and udder quality. Differences between registered research and grade research cattle were not significant.

Differences for age were significant for all traits except feet and legs, mammary and rear udder. Five year-olds scored highest in final score, general appearance, stature, breed character, back and rump, and chest and barrel. The traits relating to mammary system were scored higher on younger cows.

For final score, herds accounted for 9.6 and sires 10.1% of the variance. Heritabilities ranged from .19 for feet and legs to .68 for stature.

Indexes comparing sires' daughters to contemporaries had correlations below .90 with other indexes. Adjusting for number of daughters did not greatly alter correlations.