Effect of Select TC™ on Performance and Health Status of Newly Received Feedlot Cattle

A two-part experiment was conducted to determine the effects of Select TC™, a hydrolyzed-yeast based solution for receiving calves, on the health status and performance of steers during the first two months of the feedlot period. Eighty crossbred steers were acquired from commercial sale barns in Mississippi and Georgia, and transported to Purdue University. All animals were fed a corn silage based receiving diet, and were checked and treated daily for respiratory disease as needed following established treatment protocols. In Exp. 1, 64 steers (246.5 ± 4.7 kg initial BW) were blocked by weight and randomly allocated to 2 treatments to determine the impact of Select TC™ supplementation on health, intake and daily gain: Control (CON); and Select TC™ (TC) fed at 13 g/hd/d. Steers in Exp. 1 were housed in bedded pens with 2 animals/pen. Daily DMI was recorded, and steers were weighed every 14 d to determine performance. In Exp. 2, 16 steers (247.1 ± 5.4 kg initial BW) were similarly allotted to 2 treatments (CON and TC), individually penned, and subjected to a lipopolysaccharide (LPS) endotoxin challenge on d 62 or 63 to determine the animal’s response to an inflammatory agent. Serum samples and rectal temperatures were taken every half an hour from -2 to 8 h relative to LPS injection from steers in Exp. 2. Data were analyzed as a complete randomized block design using the MIXED procedure of SAS. Performance characteristics from Exp. 1, including weight, ADG, DMI and gain:feed, did not differ among treatments (P ≥ 0.32). Morbidity and number of animals treated once or twice did not differ in either experiment (P ≥ 0.16). During the LPS infusion in Exp. 2, there was a treatment x time effect for rectal temperatures (P = 0.05) and non-esterified fatty acid (NEFA) concentrations (P = 0.0002), where temperature and NEFA were lower pre-LPS, but greater post-LPS in CON compared to TC steers. Decreased NEFA post-LPS in TC steers suggests less break down of the adipose tissue as a source of energy for immune defenses. There were no treatment x time effects in Exp. 2 for blood urea nitrogen (P = 0.18), cortisol (P = 0.96), or insulin (P = 0.67). Results from this experiment indicate that Select TC™ improves health and metabolic status of immune challenged cattle, but this may not result in quantifiable improvements in performance.