PSIII-A-17 - Relationships Between Diet Quality and Serum Metabolic Indicators in Prenatally Stressed Growing Bos Indicus Heifers

Abstract: Our research group has previously reported on grazing behavior, diet selection, and weight change in prenatally stressed and translocated Brahman heifers grazing native rangeland. Our current objective was to evaluate relationships between diet quality and metabolic indicators. Twelve yearling heifers were transported ~700 km from Overton, TX to Sonora, TX. Six heifers (283±10 kg) were born to dams subjected to transportation stress during mid-gestation (PNS) and 6 (279±17 kg) were born to non-stressed dams (CON). Heifers grazed a series of 24-ha native range pastures and were sampled (BW, BCS score, blood, and feces) at 2-wk intervals from May through September. Fecal samples collected from the ground or the rectum of each animal were stored at -20^o C until processed for near infrared reflectance spectroscopy prediction of diet crude protein (CP) and digestible organic matter (DOM). Blood was obtained via coccygeal venipuncture and processed to yield serum. Serum analyses were obtained from the Texas A&M Veterinary Medical Diagnostic Laboratory. Relationships between constituents of interest were determined by linear regression. Significance was considered to be P < 0.05. Blood urea nitrogen (BUN; mg/dL) was greater (P = 0.04) in PNS (8.39±0.32) than CON (7.39±0.33). Positive correlations were found between CP and BUN (RSQ = 0.76, SE = 1.25 mg/dL; P < 0.001), albumin (RSQ = 0.57, SE = 0.06 mg/dL; P < 0.01), and average daily gain (RSQ = 0.63, SE = 0.47 kg; P < 0.01). Similar relationships were observed between DOM and glucose (RSQ = 0.64, SE = 3.91 mg/dL; P < 0.01), cholesterol (RSQ = 0.37, SE = 5.47 mg/dL; P < 0.05), and average daily gain (RSQ = 0.47, SE = 0.56 kg; P < 0.01). PNS affected circulating nitrogen concentration. Diet quality was related to weight gain and serum indicators of nutritional status.