Post-extraction algal residue in beef steer finishing diets: I. Nutrient utilization and carcass characteristics

Abstract

In Part I of a two-part study, an experiment was conducted to determine effects of post-extraction algal residue (PEAR) inclusion on nutrient utilization and carcass characteristics in finishing steers. Eighteen Angus×Hereford steers (initial body weight=549±38.8kg) were randomly assigned to one of three treatments for the last 35days prior to harvest: PEAR added to the ration at 1.0kg organic matter (OM)/day (PEAR), or 1.0kg OM/day glucose infused ruminally (GR) or abomasally (GA). The basal diet consisted of a standard finishing ration with additional roughage provided in the diet to prevent sudden changes in intake as a result of infusion treatments. Greater dry matter intake (DMI) was observed for PEAR (13.0kg/d) than GR (10.3kg/d; P<0.05); DMI for steers receiving GA (11.2kg/d) was intermediate and not different from either PEAR or GR (P≥0.14). Intake of digestible energy (DE) was similar among treatments (P=0.45) and averaged 36 Mcal/d as was digestible OM intake which averaged 8.8kg/d (P=0.51). Digestion of gross energy (GE) was 72.9, 82.6, and 80.9% for PEAR, GA, and GR, respectively (P<0.01). Digestion of neutral detergent fiber (NDF) was substantially less (55.7%) for PEAR than GA (75.4%) and GR (75.0%; P<0.01). Steers fed PEAR had greater marbling scores (Mt20) than GA (Sm63) and GR (Sm52; P=0.01). Accordingly, USDA Quality Grade was greater for PEAR than GA and GR (P=0.01; Ch40, Ch21, and Ch17, respectively). There was no difference in USDA Yield Grade or hot carcass weight (HCW) between treatments (P≥0.66). In Part II, flavor and fatty acid composition of beef cuts from carcasses used in this study were assessed, and results are addressed in a separate publication.