Effects of feeding a Saccharomyces cerevisiae fermentation prototype on performance, carcass characteristics, and liver abscess prevalence of beef heifers at a commercial feedlot

Abstract

ABSTRACT Animal agriculture continues to look for new, non-antibiotic feed solutions that can be used in conventional and natural feedlot systems to help improve cattle health and performance. Therefore, crossbred heifers (n = 1,495; 359 ± 10.75 kg; 20 pens total) were used in a randomized complete block design study at a commercial feedlot to determine the effects of a proprietary Saccharomyces cerevisiae fermentation prototype on performance, carcass characteristics, and liver abscess prevalence when monensin, tylosin, and direct-fed microbials were not included in the diet. Heifers were fed a diet containing (1) monensin, tylosin, and a direct-fed microbials (PC) or (2) a Saccharomyces cerevisiae fermentation prototype (PRT; NaturSafe, Diamond V, Cedar Rapids, IA) at 18 g/head daily without PC. Diets were fed twice daily with heifers receiving half of the daily dose of treatment in the TMR at each feeding. Pen BW were collected on d 0 and before slaughter. Daily measurements recorded while cattle were in the feedlot included feed intake, morbidity, and mortality. Cattle were shipped to slaughter on d 125 and 146 (5 pens per treatment per day). Carcass data collected included HCW, DP, QG, YG, KPH, rib fat thickness, LM area, marbling score, and liver abscess scores. Data were analyzed with the MIXED procedure (continuous) and GLIMMIX procedure (categorical) of SAS. Treatments were similar (P ≥ 0.16) for final BW (580 vs. 580 kg), ADG (1.64 vs. 1.63 kg/d), G:F (0.159 vs. 0.156 kg/kg), HCW (366 vs. 367 kg), other carcass characteristics, morbidity (0.3 vs. 0.0%), and mortality (0.77 vs. 0.70%). Heifers fed PRT had a numerically lower (P = 0.27) prevalence of liver abscesses with fewer livers having less severe (i.e., A−) abscesses. Replacing monensin, tylosin, and direct-fed microbials in conventional feedlot diets with NaturSafe resulted in similar growth performance, carcass characteristics, and liver abscess prevalence in feedlot cattle.