Date of Graduation
Bachelor of Science in Agricultural, Food and Life Sciences
Multiple methods of pregnancy detection can be used in sheep production. The gestation period for sheep is usually between 144 and 150 days; however, depending on the breed and age of the ewes, this number can vary. A breeding marker, such as a breeding crayon, is used to detect when the ewe is bred by the ram, and the date the ewe will lamb is typically calculated based on an average 145-day gestation. Unfortunately, this method provides only a rough estimate of when the ewe could lamb. In addition, because sheep routinely give birth to multiples (twins, triplets, and, sometimes, quadruplets), ewes are renowned for dystocia; thus, the ability to pinpoint the time of parturition to a 24-hour, rather than a five-day, window would enable sheep producers to be prepared for any difficulties, thereby reducing newborn lamb mortality. In horses, the time of parturition can be detected within 24 to 48 hours by measuring calcium concentrations in prepartum milk using the Chemetrics K-1700 testing system. Therefore, the objective of this research was to test the effectiveness of measuring calcium concentrations in prepartum ewe’s milk to predict time of parturition in pregnant ewes. The study was designed to collect 10 to 20 mL of ewe’s milk twice daily, beginning four days before the calculated date of parturition until lambing. Because the Chemetrics K-1700 testing system is a rapid-test, milk calcium concentrations will be determined within minutes of hand-milking each ewe. It is standard practice to collect “extra” colostrum for orphaned or sickly lambs roughly 12 hours postpartum and after the newborn lamb(s) have ingested sufficient quantities of their mother’s colostrum and establish their maternal bonds. Therefore, at approximately 12 hours postpartum, an approximate 25-mL sample of colostrum was collected to measure the immunoglobulin quality of the colostrum using three methods (Colostrum Refractometer, Antifreeze tester, and Equine Colostrometer. Unfortunately, a large enough sample size was not collected to accurately analyze the milk samples using the Chemetrics K-1700. When we analyzed the calcium levels in the colostrum, we found that the colostrum quality was similar using the Anti-freeze tester to that of the Colostrum Refractometer, and was significantly different than the Equine Colostrometer. The Anti-freeze tester was also more highly correlated to the Colostrum Refractometer than that of the Equine Colostrometer.
Keywords: sheep, colostrum, immunoglobulin quality, mammary secretions
Watson, Lensey, "Predicting the Onset of Parturition by Determining Calcium in Prepartum Milk of Sheep" (2017). Animal Science Undergraduate Honors Theses. 12.