Effects of hydrolyzed yeast on weanling pig growth performance, fecal dry matter, and stress-related blood antioxidant criteria.

Abstract

A total of 360 weanling pigs (241 × 600, DNA; initially 5.4 ± 0.01 kg) were used to evaluate the effects of a hydrolyzed yeast product (HY) on growth performance, fecal dry matter (DM), and stress-relevant blood antioxidant criteria. Pens of pigs were randomly allotted to one of six dietary treatments in a generalized randomized block design with 5 pigs per pen and 12 pens per treatment. Pigs were blocked with 4 replications of light (4.3 ± 0.01 kg), medium (5.4 ± 0.01 kg), and heavy (6.5 ± 0.01 kg) weight pens per treatment. Diets were corn-soybean meal-based and consisted of a negative control (NC) diet, a positive control (PC) diet which was the NC diet + 55 mg/kg carbadox, the PC diet with 0.04% HY, and the NC diet with either 0.04, 0.08, or 0.12% HY. Linear and quadratic contrasts were tested within increasing levels of HY in diets without carbadox. The main effect of carbadox was evaluated by comparing the average of 0 and 0.04% HY in the presence and absence of carbadox. Treatment diets were fed in three phases from d 0 to 10 (phase 1), d 10 to 24 (phase 2), and d 24 to 45 (phase 3). On d 10 and 24, fecal samples were collected from the same three initially randomly selected pigs in each pen to determine fecal DM and fecal scores. Blood samples were collected on d 10 and 45 from the same representative pig in each pen for total antioxidant capacity (TAC) and superoxide dismutase (SOD). Overall (d 0 to 45), final weight increased (P < 0.05) while average daily gain (ADG) and average daily feed intake (ADFI) tended to increase (P < 0.10) for pigs fed diets containing carbadox compared to pigs fed diets without carbadox. Gain:feed ratio (G:F) increased (P = 0.017) when 0.04% HY was added to the negative and positive control diets. On d 10, increasing HY in diets without carbadox increased fecal DM (linear, P = 0.005). Additionally, pigs fed carbadox had increased (P < 0.05) fecal DM on d 10 and 24 compared to pigs not fed carbadox. There were no treatment differences observed on d 10 for TAC; however, TAC decreased (linear, P = 0.008) on d 45 as HY increased in the diet. Increasing HY tended to decrease (linear, P = 0.095) serum SOD activity on d 10 while no treatment differences were observed on d 45. In summary, pigs fed carbadox had increased overall ADG and fecal DM. Increasing HY inclusion did not affect growth performance; however, fecal DM was improved during the early nursery period. Additionally, feeding 0.04% HY improved overall G:F.