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The Relationship between Type Ratings of Ayrshire Females as Young Heifers and as Cows¹

ABSTRACT

One hundred and two Ayrshire heifers at the West Virginia Agricultural Experiment Station have been rated for type starting at 6 or 12 months of age and at 6-month intervals thereafter until 4 or 5 years of age. The intra-animal standard deviation was 0.62 when the ratings were made before first calving, and 0.65 when they were given after calving.

In terms of range, five animals (4.9 per cent) were classified the same whether rated as heifers or milking cows, 52 (51.0 per cent) varied one grade, while 39 (38.2 per cent) varied two grades and six (5.9 per cent) varied three grades.

There were 33 heifers classified at 6, 12, 18 and 24 months of age and 73 heifers classified at 12, 18 and 24 months. The average of the ratings at the different ages was approximately the same.

The correlations between the average of the several ratings of each heifer before first calving and the first and second ratings after calving were 0.37 and 0.40, respectively.

The average type ratings of the heifers before calving were compared with the average ratings after calving by placing the heifers in four groups (below 80.5, 80.5 to 82.5, 82.6 to 85.0, above 85.1) according to the average of their ratings before first calving. The low group remained the lowest following calving, while the high group still maintained the highest average score, but both averages were closer to the general mean. The two middle group averages changed very little following freshening.

With improvement in and standardization of classification methods, particularly for heifers, the classification program may become valuable in helping breeders to cull the poorest type individuals from their herds at an early age.

¹ Published with the approval of the Director, West Virginia Agricultural Experiment Station, as Scientific Paper no. 402.

² Professor of Dairy Husbandry, West Virginia University, Morgantown.

³ Assistant Professor, Department of Dairy Husbandry, West Virginia University, Morgantown.

⁴ Executive Secretary, Ayrshire Breeders' Association, Brandon, Vermont.