title: Effects of feeding extruded full-fat cottonseed pellets in place of tallow as a fat source for finishing heifers on feedlot performance, carcass characteristics, sensory traits, display color, and fatty acid profiles.
abstract: The objective of this study was to examine the effects of supplemental feeding of full-fat extruded cottonseed pellets (FFECS) compared with tallow on carcass characteristics, sensory traits, retail display color, and fatty acid profiles, especially CLA isomers in finishing heifers. Twenty-one Angus heifers (450 ± 5 kg) were assigned randomly to 1 of 3 experimental diets: 1) 100% supplemental fat from tallow at 4.1% of ration DM (TAL), 2) a 50:50 ratio of supplemental fat from a combination of tallow at 2.1% and FFECS at 12.8% of ration DM (TAL/ECS), and 3) 100% supplemental fat from FFECS at 25.6% ration DM (ECS). All rations were formulated to contain 7.5% fat on a DM basis. Heifers were individually fed, ad libitum, for 82 d, and BW, G:F, DMI, ADG, and body composition via ultrasound were collected at 3 to 4 wk intervals. After 82 d on feed heifers were slaughtered under federal inspection, and carcass characteristics were measured (at 24 h). The LM was removed for retail display color (1, 3, 6, 10 d), Warner-Bratzler shear force (1, 3, 7, 14, 21 d postmortem aging), sensory analysis (1, 7, 14, 21 d postmortem aging), and fatty acid profile analysis. Subcutaneous fat, including all layers, was removed from the LM for fatty acid profile analysis, and ground beef patties (80:20) were produced with lean from the brisket and fat from the plate for retail color analysis (1, 2, 4, 7 d). Supplemental fat source did not influence feedlot performance for any of the traits measured (P > 0.12) or any carcass traits related to yield, quality, or LM color at the 12th- to 13th-rib interface (P > 0.15). Supplemental fat source did not affect Warner-Bratzler shear force or any sensory traits (P > 0.20), but LM steaks became more tender as postmortem aging time increased up to 14 d (P < 0.01). During retail display of LM steaks and beef patties, the only difference was LM steaks from ECS were darker (lower L* value) than TAL or TAL/ECS steaks (P < 0.02). As display time increased, LM steak and beef patty objective and subjective color deteriorated (P < 0.01). Although feeding FFECS compared with tallow increased linoleic acid (C18:2(n-6)) in both intramuscular and subcutaneous fat (P < 0.04), this did not lead to an increase in total CLA content (P > 0.90). Full-fat extruded cottonseed pellets are interchangeable with tallow in heifer finishing diets without impacting feeding performance, meat quality, shelf life color, or CLA content of adipose sites.
authors.affiliation: Department of Animal and Dairy Science, University of Georgia, Athens, GA 30602, USA. astelz@uga.edu
authors.forename: A M
authors.initials: AM
authors.lastname: Stelzleni
authors.forename: M A
authors.initials: MA
authors.lastname: Froetschel
authors.forename: T D
authors.initials: TD
authors.lastname: Pringle
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000822:Animal Husbandry; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001823:Body Composition; D002417:Cattle / Q000254:growth & development / Q000502:physiology*; D003369:Cottonseed Oil / Q000008:administration & dosage / Q000378:metabolism*; D004032:Diet / Q000662:veterinary; D005223:Fats / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D019787:Linoleic Acid / Q000378:metabolism; D008460:Meat / Q000032:analysis*; D009829:Oleic Acids / Q000378:metabolism; D012417:Rumen / Q000378:metabolism
chemical_list: D003369:Cottonseed Oil; D005223:Fats; D009829:Oleic Acids; C013698:tallow; D019787:Linoleic Acid; C050413:11-octadecenoic acid