Masters Theses

Date of Award


Degree Type


Degree Name

Master of Science


Animal Science

Major Professor

J. B. McLaren

Committee Members

K. M. Barth, Paul C. Smith


Fifty-four weanling steer calves were sxibjected to one of three pre-shipment treatments: (1) normal industry stresses (Normal Industry); (2) fed a high-energy, high-antibiotic diet in the order-buyer barn (High Energy) ; or (3) preweaned and fed a concentrate diet for 30 days before marketing (Preweaned). After being exposed to commercial auction and order-buyer barn environments for 4 days, the steers were assigned to one of three post-shipment treatments: (1) nonbuffered control (Nonbuffered); (2) 40 grams of sodium bicarbonate per steer per day (40- gram-NaHCO3); and (3) 80 grams of sodium bicarbonate per steer per day (BO-gram-NaHCO3) in a 3X3 factorial arrangement with pre-shipment treatments.

Ruminal pH and in vitro gas production values decreased as the steers progressed through the normal sequence of market-transit events (auction barn, order-buyer barn and trucking) and were significantly lower upon arrival at the feedlot than at the farm of origin or upon arrival at the auction barn. Pre-shipment concentrate feeding at the farm of origin or in the order-buyer barn significantly reduced ruminal pH and increased in vitro gas production. In steers subjected to normal industry market-transit stresses, increased gas production was observed in the 40- and 80-gram NaHCO3-supplemented groups on feedlot sampling day 4, 11 and 32. However, in calves preweaned and fed a concentrate diet at the farm of origin or order-buyer barn no response to feedlot NaHCO^ supplementation was observed until feedlot day 32 and these responses were inconsistent and of lower magnitude than in the normal-industry-stressed steers. Packed cell volume, total serum protein, red blood cell count, white blood cell count and rumen protozoa concentration were not affected by feedlot sodium bicarbonate supplementation.

There was a significant pre- by post-shipment treatment interaction with respect to feedlot gain. Feeding 80 grams of NaHCO3 to Normal-Industry stressed steers and feeding 40 grams NaHCO3 to High- Energy steers resulted in higher cumulative ADG to feedlot day 11 than the respective Nonbuffered groups. In Normal-Industry NaHCO3-buffered steers, feedlot time required to regain market-transit shrink was shorter, illness index was lower, and elevated early feedlot rectal temperatures returned to normal values quicker than in Nonbuffered steers. In High-Energy steers the 40 grams NaHCO3 resulted in higher early-feedlot gains but had no effect on rectal temperatures and in Preweaned steers, the Nonbuffered steers gained faster to feedlot day 11 than the other NaHCO3 groups. Although, NaHCO3 increased the rate of feedlot adaptation, its beneficial effects were limited to the early feedlot period when used as a buffering agent with a high corn-silage ration.

Preweaned steers gained more weight at the farm of origin. High- Energy steers lost more weight during the auction-barn, order-buyer barn .phase and Normal Industry steers lost more on the truck than steers in the other two groups, respectively. However, total market-transit weight loss was similar for the three pre-shipment treatments.

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