Effects of antibiotic alternatives and exogenous enzymes on growth performance, nutrient utilization and gut health of broiler chickens

Hang Lu, Purdue University

Abstract

Two studies were performed for this thesis. In study 1, effects of antibiotic alternatives on growth performance and immune response of broiler chickens challenged with Eimeria oocysts in coccivac B vaccine were investigated. The study was a randomized complete block design with 6 treatments and 8 replicate pens per treatment. The six treatments tested were; negative control (NC) with neither antibiotic nor antibiotic alternatives, Salinomycin positive control (PC), essential oil (Orego-Stim®), commercial yeast (Alphamune™), direct fed microbial (Avicorr® ®) and crude yeast extract. The study lasted 42 d and measurements were taken on d 21 and 42. There was no significant difference in the final body weight (BW), daily gain (BWG) between treatments on d 21. However, d 42 BWG of birds supplemented with Salinomycin was higher (P < 0.05) than the Avicorr and Orego-Stim treated groups. Additionally, feed efficiency was improved (P < 0.05) by Salinomycin compared with NC and Orego-Stim treatments. Expression levels of genes were not different among treatments on d 21. However on d 42, lipopolysaccharide- induced TNF-alpha factor (LITAF) was lower (P < 0.05) in the Orego-Stim treatment group than NC. In addition, birds treated with crude yeast had higher (P < 0.05) level of IL-10. Similarly, IFN-γ and TLR-4 were lower with Orego-Stim supplementation and higher with crude yeast (P < 0.05). In the digestibility trial, Salinomycin and crude yeast treated birds had higher apparent ileal DM, energy, N and P digestibility on d 21. However, these differences were no longer apparent on d 42. Overall, these results confirm the expected improvement in animal performance with antibiotic (Salinomycin) and further show reduced bio-markers of inflammation with organic acid (Orego-Stim) treatment in broiler chickens. Study 2 was conducted to determine the effects of combination of carbohydrases and phytase on performance, nutrient digestion and absorption, gut health and integrity, and immune status of broiler chickens. A total of 448 day-old broilers were randomly assigned to 4 treatments including a positive control (PC, meets the nutrients requirements by NRC,1994), a negative control (NC, deficient in ME, CP, Ca and nPP, relative to the PC, by 100 kcal/kg, 5g/kg, 1.1g/kg and 1.6g/kg) and 2 test diets with Rovabio® Max at 0.05 and 0.075 g/kg diet. On d 21 and 42, one bird per pen was killed for gene expression analyses of mucin (MUC2), interleukin 1 (IL-1β) and phosphorus transporter (NaPiIIb) by RT-PCR in mucosal samples from the duodenum, jejunum, ileum. Five birds per pen were moved to steel cages for the digestibility study on d 21 and 42. Body weight (BW) and average daily gain (ADG) were linearly increased by Rovabio® Max supplementation on d 21 and 42 (P < 0.05). Rovabio Max linearly increased the feed intake (FI) from d 21 to 42 and overall (P < 0.05). The gain to feed ratio was significantly (P < 0.05) improved by Rovabio® Max from day 0 to 21, d 21 to 42 and overall. Additionally, higher serum phosphorus (P) was observed with Rovabio® Max addition to the diets (P < 0.05). There were no gene expression differences between treatments. In the digestibility experiment, on d 21, there were no significant differences in dry matter (DM), energy and nitrogen (N) apparent ileal digestibility (AID). However the AID of P was increased by Rovabio ® Max (P < 0.05) by 119%. On d 42, Rovabio ® Max increased the AID of DM, energy, P and N (P < 0.05) by 9.4%, 8.5%, 21.7% and 5.0% respectively. Overall, these results confirm that Rovabio® Max supplementation leads to improvement in growth performance of broiler chickens and also resulted in increased energy and P utilization.

Degree

M.S.

Advisors

Ajuwon, Purdue University.

Subject Area

Animal sciences

COinS