Post-extraction algal residue in beef steer finishing diets: I. Nutrient utilization and carcass characteristics
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2017 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 38.8 kg) were randomly assigned to one of three treatments for the last 35 days prior to harvest: PEAR added to the ration at 1.0 kg organic matter (OM)/day (PEAR), or 1.0 kg 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 (13.0 kg/d) than GR (10.3 kg/d; P < 0.05); DMI for steers receiving GA (11.2 kg/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 8.8 kg/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.