PSIX-20 Mechanisms of Programmed Nutrition in finishing cattle

Abstract

Abstract Programmed Nutrition Beef Program (Alltech Inc.) is a supplement that could reduce the use of feed additives such as Monensin and Tylosin in feedlots. The objective of this study was to examine changes in rumen fermentation when feeding Monensin/Tylosin and Programmed Nutrition. Eight steers (BW = 363 ± 22 kg) were used in a replicated 4 x 4 Latin square design experiment in a 2 x 2 factorial treatment structure where animals were fed a high-concentrate diet at 2.0 x NEm. Treatments were Control (C; conventional trace mineral supplement), Control + Monensin + Tylosin (MT), Programmed Nutrition (PN; Programmed Nutrition Beef Finisher), or Programmed Nutrition + Monensin + Tylosin (PNMT), incorporated daily to the diet at 75 g/day. Rumen pH was measured continuously for 48 h, rumen fluid was collected every 2 h for 48 h and analyzed for VFA. Dietary digestibility, nitrogen and energy balance were determined by collection of total urine and fecal output for 7 days, and indirect calorimetry for 48 h. Protein turnover was determined via 15N-glycine end-product method. The experiment was analyzed as a replicated Latin square design with mixed models of SAS (SAS Inst. Inc.). Mean differences were analyzed using LSD, rumen VFA and pH data were analyzed using repeated measures. There were no differences between treatments in DMI, ADG, dry matter digestibility and rumen pH. Addition of MT to the diet lowered fecal N output (P = 0.0092), ruminal valerate concentration (P = 0.0125) and molar proportion (P = 0.0235). When PN was fed in combination with MT it decreased ADF digestibility (P = 0.0342), protein turnover (P = 0.0211), protein synthesis (P = 0.0362) and protein degradation (P = 0.0292). Although no differences in ADG and dry matter digestibility were observed, significant metabolic changes occurred when supplementing PN with or without MT.