Effects of dietary enzymes on performance and intestinal goblet cell number of broilers exposed to a live coccidia oocyst vaccine

Abstract

An experiment was conducted to evaluate the effects of dietary enzymes on performance, tibia ash, and intestinal goblet cells of broilers administered a live coccidia oocyst vaccine (Coccivac B, Schering Plough, Kenilworth, NJ). Cobb 500 straight-run broilers were obtained and one-half of the chicks were sprayed with the live coccidia oocyst vaccine. Chicks were weighed and placed in battery brooders with respect to nonvaccinated or vaccinated group according to dietary treatment. The 8 dietary treatments were a positive control (0.90% Ca and 0.45% available P), a negative control (NC; 0.80% Ca and 0.35% available P), NC + phytase (PHY), NC + protease (PRO), NC + xylanase (XYL), NC + PHY+ PRO, NC + PHY + XYL, and NC + PHY + PRO + XYL. A diet × vaccination interaction (P > 0.05) was not observed for feed intake or BW gain. Feed conversion ratio was improved (P ≤ 0.05) in birds fed NC + PHY + XYL compared with NC. Vaccination reduced (P ≤ 0.05) feed intake and BW gain from d 0 to 18. Tibia ash was reduced (P ≤ 0.05) in the NC and PRO or XYL diets. Vaccination increased goblet cell numbers in the duodenum of birds fed XYL, whereas no differences were found in goblet cell numbers between nonvaccinated and vaccinated birds in other dietary treatments, which resulted in a diet × vaccination interaction (P ≤ 0.05). Protease decreased and NC + PHY+ PRO increased goblet cells in the jejunum at d 7, which resulted in a diet × vaccination interaction (P ≤ 0.05). At d 18, NC + PHY + XYL was the only diet in which vaccination decreased goblet cells in the jejunum, resulting in a diet × vaccination interaction (P ≤ 0.05). The data indicate that NC + PHY + XYL improved the feed conversion ratio in broilers fed corn-soybean meal diets. The vaccination × dietary enzyme interaction altered the number of goblet cells in the small intestine. Dietary enzyme supplementation did not alleviate reductions in growth performance associated with the use of a live coccidia oocyst vaccine.