CHARACTERIZATION OF OVIDUCT SECRETIONS IN THE HYPERTHERMIC EWE

JOHN ARTHUR KNESEL, Purdue University

Abstract

Two experiments were conducted within psychrometric chambers to explore underlying cause-and-effect mechanisms of direct and indirect harmful effects upon embryos in the hyperthermic ewe. In the first experiment, rectal and oviduct temperatures were monitored simultaneously in four ewes exposed to 32.2, 35.0, and 37.8 C (with 70% and 90% relative humidities at each temperature), and a thermoneutral 21 C/50% RH environment. In the second experiment, two groups of four ewes each were exposed to 35.0 C/65% RH and 21.1 C/50% RH according to a cross-over experimental design. During exposure to both environments, oviduct secretions were collected from right and left oviducts via indwelling cannulae. Volume, total protein content, and tricarboxylic acid cycle intermediates were measured. In the first experiment, rectal and oviduct temperatures increased significantly during most exposures to elevated temperatures, particularly at higher humidity levels. There was, however, a high degree of between-ewe variation, and each ewe was considered separately with respect to data analysis. Temperatures in the rectum and oviduct exhibited increases ranging from .28 to 1.66 C and .22 to 2.33 C, respectively. In 10 of 24 rectal temperature increases and 11 of 20 oviduct temperature increases, levels exceeded the 1.0 C hyperthermia which has been cited as causing direct harm to gametes and embryos. The volume of oviduct secretion was not affected by hyperthermia and ranged from .25 to 3.30 ml/24 hours. However, volume was significantly affected by time in the breeding season when the sample was obtained, as well as day of the estrous cycle. Characteristic patterns of secretion with post-estrous elevations in volume were observed. Total protein content was not affected by hyperthermia; protein content did vary significantly with day of cycle. Malic, fumaric, succinic, and a complex of citric, isocitric, and oxaloacetic acids were identified in secretions, but the effects of hyperthermia, if any, could not be determined. Four ewes exhibited a delay in onset of estrus upon exposure to 35.0 C/65% relative humidity. It was concluded from these experiments that the oviduct is a relatively stable compartment with respect to volume and total protein and that perhaps the harmful effects of temperature might be more likely caused by the direct effect of elevated temperatures.

Degree

Ph.D.

Subject Area

Anatomy & physiology|Animals

COinS