A study of the relationships between body characteristics and ovarian activity in Hereford heifers

A study involving 145 Herford heifers was con-ducted at The University of Tennessee, Main Experiment sta-tion, Knoxville, Tennessee. The purpose of this study was to determine the relationship between certain measurements of body charac-teristics and ovarian activity. Characteristics measured consisted of body fat thickness, body weight, body length, wither height, hook height, marbling score and animal age. The phrase "ovarian activity" denoted the total number of corpora lutea and corpora albicans found by cross-section ing each ovary. The mean ovarian activity for the left ovary was 3.3 ± 1.5 and for the right ovary was 3.7 ± 1.6. The mean left ovary weight was 5.9 ± 2.4 grams and the mean right ovary weight was 6.0 ± 2.6 grams. It was noted, how ever, that as the right ovary weight increased the right ovary activity also increased. The mean initial fat thickness, final fat thick-/ ness, and increase in fat thickness were 2.5 ± mm, 12.5 ± 2.7 mm and 9.9 ± 2.71 mm, respectively. However, neither left nor right ovarian activity was found to be significant-ly influenced by fat thickness (P < .05). The mean initial body weight, mean final weight and mean weight gain were 438 ±29.3 lbs., 990 ± 75.0 lbs. and 456 ± 70.4 lbs., respectively. As initial animal weights became higher the activity of the left ovary also increased. Neither initial weight nor final weight exerted any in fluence on the weights of the left or right ovaries. The means for body length, wither height, hook height and marbling score were 127.2 ±4.6 cm, 64.1 ± 2.3 cm, 110.6 ± 3.3 cm and 5.6 ± 1.2, respectively. The only significant variable was marbling score (P -< .10). The means for initial age, final age and time on test were 261.'8 ± 56.7 days, 524.8 ± 69.3 days and 263.0 ± 25.8 days, respectively. Initial age was also significantly correlated to left and right ovary weight (P < .05). Signi-ficant correlations were found between final age and left and right ovary weights (P < .05).