Eighteen barrows with a T-cannula in the distal ileam were utilized in a study evaluating the impact of tylosin phosphate on amino acid and energy digestibility in cornsoybean meal and corn-soybean meal-distillers dried grains with soluble (DDGS) based diets. There were no interactions between the responses to tylosin phosphate and DDGS (P>0.10). DDGS inclusion reduced the standardized ileal digestibility of most indispensible amino acids (P<0.05) and the apparent ileal digestibility and apparent total tract digestibility of energy. Under the conditions of this experiment, tylosin phosphate did not affect digestibility of amino acids or energy and the inclusion of DDGS did not affect the response to TP.Tylosin phosphate is a macrolide antibiotic used in swine diets to control diseases, such as ileitis and swine dysentery, and to improve growth performance. At least four mechanisms have been proposed as explanations of the growth promoting effects of antibiotics: 1) inhibition of sub-clinical infections, 2) reduction of growth-depressing microbial metabolites, 3) reduction of microbial use of nutrients, and 4) enhanced uptake and use of nutrients through the thinner intestinal wall associated with antibioticfed animals. The objective of this study was to evaluate the impact of tylosin phosphate on amino acid and energy digestibility in growing pigs fed corn-soybean meal or cornsoybean meal- DDGS based diets.Materials and MethodsThis study was conducted at the Iowa State University Swine Nutrition Farm under the approval of the Institutional Animal Care and Use Committee (#2-10-6900-S). Eighteen barrows (initial BW=76.9±2.20 lbs.) were surgically fitted with a T-cannula in the distal ileum. Treatments were arranged in a 2×2 factorial: tylosin phosphate (0 vs. 44 ppm) and DDGS (0 vs. 25%). Two nitrogen-free dietary treatments (0 vs. 44 ppm tylosin phosphate) were also included for determining basal ileal endogenous amino acid losses (IAAend) to calculated standardized ileal digestibility (SID) of AA. Replicate periods included 4 d of adaptation to treatments and two sampling periods (SP1 and SP2). Fecal collection occurred on d 5 and 6 and ileal digesta collection on d 7 and 8 for SP1; SP2 included fecal collection on d 11 and 12 and ileal digesta collection on d 13 and 14. For N-free treatments, corn-soybean meal diets were fed d 1 through d 7 followed by a 5-d adaptation to N-free diet and ileal digesta collection on d 13 and 14. All samples from SP1 and SP2 were analyzed for dry matter and gross energy, and amino acid analysis was conducted on ileal digesta samples from SP2.ResultsResults of this study are presented in Table 1 and Table 2. There were no significant interactions (P>0.10) between tylosin phosphate, DDGS or sampling period. Inclusion ofDDGS reduced apparent ileal digestibility (65.3 vs. 71.9%; P<0.0001) and apparent total tract digestibility (79.7 vs. 85.5%; P<0.0001) of energy. There were no effects of tylosin phosphate on energy digestibility. There were no effects of tylosin phosphate on basal IAAend (P>0.10); therefore, standardized ileal digestibility of amino acidvalues were calculated using means of the two nitrogen-free diets. The standardized ileal digestibility of Lys (79.6 vs. 84.1%; P<0.0001) and all other indispensible amino acids, except Leu, was lower in the DDGS diets. Inclusion of tylosin phosphate did not influence standardized ileal digestilbity of AA.
Chad Pilcher, graduate research assistant;John Patience, professor,Department of Animal Science
Source: Iowa State University