Date of Award:

5-1984

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Animal, Dairy, and Veterinary Sciences

Department name when degree awarded

Animal, Dairy and Veterinary Medicine

Committee Chair(s)

Warren C. Foote

Committee

Warren C. Foote

Committee

James A. Bennett

Committee

Jeffrey L. Walters

Committee

Ronald V. Canfield

Committee

Thomas D. Bunch

Abstract

Body size was estimated by multiplying the average of the hip and chest widths by body length and chest depth in 208 ewes of three genotypes: Targhee x Targhee (TXT), Finn x Targhee (FXT), and Suffolk x Targhee (SXT), and two seasons, fall (pre-breeding) and spring (post-lambing). The estimated ewe body size did not fluctuate with season, body condition or physiological stress and proved to be a constant measure of size. Measuring linear body dimension is time consuming; and hence ewe body size can best be approximated by the chest depth in a regression equation. In the absence of linear measurements, the ewe body weight remained to be the best measure of size.

In evaluating relationships, there was a tendency for ewe body size and weight to be positively (P < .05) related to reproductive traits and body condition to be negatively (P < .05) related. The heavier ewes were more prolific in the FXT ewes and the lighter ewes in the SXT ewes, the TXT ewes being intermediate. Lamb production on per unit size or weight bases tended to be negatively (P < .05) related with weight and/or size in all the three genotypes. This relationship was stronger in the SXT ewes than in the TXT ewes, which in turn was stronger than in the FXT ewes, suggesting that the heavier/larger the ewe the less she produced in relation to her weight or size.

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