title: Performance and carcass characteristics of weaned lambs either grazed on orchardgrass, ryegrass, or alfalfa or fed all-concentrate diets in drylot.
abstract: Four-paddock rotational grazing of orchardgrass, ryegrass, or alfalfa was compared to an all-concentrate diet fed in drylot using 202 weaned lambs. Comparisons of animal performance ended in each of the 3 yr (1983, 1984, 1985) for all animals when drylot lambs reached a subjective body condition score of 12 (range 1 to 15) and estimated fat depth over the rib was 5.5 to 7.0 mm. A total of 84 representative lambs were slaughtered over the 3 yr for carcass evaluation. Mature put-and-take ewes were used to maintain forages in the vegetative stage. Average daily gain and total gain of lambs were in the order of drylot > alfalfa > grasses; performance of lambs grazing alfalfa approached performance of those fed the drylot diet. Better performance (P < .01) of lambs grazing alfalfa than of those grazing grasses is atributed to more CP (P < .01) and less NDF, ADF, and hemicellulose (P < .01) in alfalfa. Lambs grazed on grasses had smaller carcasses with less muscle, fat, and bone (P < .01) than either of the other two treatments. Although carcasses of lambs grazed on alfalfa were lighter, they had the same muscle mass as concentrate-fed lambs, indicated by leg conformation, longissimus muscle area, and by physically separated absolute muscle weight. However, these carcasses contained less fat (P < .01) and had more desirable yield grades (P < .01) than the carcasses of concentrate-fed lambs.
authors.affiliation: Department of Animal Science, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691.
authors.forename: K E
authors.initials: KE
authors.lastname: McClure
authors.forename: R W
authors.initials: RW
authors.lastname: Van Keuren
authors.forename: P G
authors.initials: PG
authors.lastname: Althouse
mesh_terms: D000821:Animal Feed / Q000592:standards*; D000818:Animals; D001823:Body Composition / Q000502:physiology; D005260:Female; D005526:Food, Formulated / Q000592:standards; D008297:Male; D008460:Meat / Q000592:standards; D000455:Medicago sativa / Q000592:standards*; D006109:Poaceae; D011897:Random Allocation; D012756:Sheep / Q000254:growth & development*; D013025:Glycine max / Q000592:standards; D014886:Weaning; D015430:Weight Gain / Q000502:physiology*; D003313:Zea mays / Q000592:standards