An anatomical, histological, and physiological study of Santa Gertrudis cows with normal and poor records of reproduction

Abstract

Forty Santa Gertrudis cows ranging in age from 3 to 13 years of age were used in this study. Those animals considered to have normal records had a calving interval of 467 days or less and had been "open" for 150 days or less following their last calving. Animals not meeting these criteria and those that had not produced a calf were considered to have poor records. The animals were observed for estrus and bred artificially. Cows not showing estrus were slaughtered after 30 days. Cows that were bred were slaughtered 3 or 4 days after estrus. Ova were flushed from the oviducts and cultures taken from the uteri and cervices. Weights of ovaries, pituitaries, thyroids, and adrenals were taken. Tissue samples were taken from the reproductive tract and the endocrines. The serum calcium, phosphorus, and protein were determined and the T³RBC test was employed to determine thyroid activity. Eighty per cent of the cows in the normal group and 73 per cent of the cows in the poor group showed some sign of estrus. The incidence of silent estrus was 40 per cent and 10 per cent, respectively, for the normal and poor groups. Ovulation in 71.4 per cent of the normal cows and 95.2 per cent of the cows with poor records while fertilization rates were 50 per cent and 52.9 per cent, respectively. Ninety per cent of the cows in both groups had active ovaries. Ten per cent of the cows in each group possessed some blockage of one or both of the oviducts. An enlarged cervix was found in 40 per cent of the cows with poor records. The frequency of this anomaly in cows which had 4 or more calves was 50 per cent, while in those which had never calved it was 30 per cent. Cervices with diameters up to four and one-half inches and lengths to nine inches were observed. Inflammation of the uterus was observed in 50 per cent of the normal and 40 per cent of the poor animals. Twenty per cent of the uterine cultures from cows in the normal group, and 30 per cent from cows in the poor group contained pathogenic organisms. Histological study of the ovaries, oviducts, uteri, cervices, pituitaries, thyroids, and adrenals yielded slight differences which did not constitute a criterion for determining reproductive ability. Sera from normal and poor groups were essentially the same as were the T³RBC results.