title: Corn supplementation of lambs grazing alfalfa.
abstract: We investigated the effects of supplementing Rambouillet x Suffolk wether lambs grazing irrigated 'Cimarron' alfalfa (Medicago sativa L.) with three levels (0 [C0], 123 [C123], and 247 [C247] g of DM.lamb-1.d-1) of cracked corn. Each treatment group also received 190 g of a supplement designed to prevent bloat. Replicated pastures (three per treatment) grown on a fine, mixed, thermic Torretic Paleustoll soil were grazed rotationally (forage plus supplement allowance of 6.5% of BW/d) by lambs for 85 d during spring 1992. Supplemental corn levels were analyzed as single degree of freedom contrasts for linear and quadratic effects. At the start of the experiment, lambs weighed 30.7 +/- .32 kg. Average daily gains for C0 C123, and C247 were 141, 154, and 169 g/d, respectively. Lamb production per hectare increased quadratically (P < .01) with increasing corn level (C0 [716 kg of lamb/ha], C123 [816 kg of lamb/ha], and C247 [964 kg of lamb/ha]). Supplementation with C247 vs C0 increased carcass weights (11%), dressing percentage (6%), and backfat thickness (30%). Plasma urea N (PUN) concentrations did not differ (P > .10) between C0 and C123 after 27 d of corn supplementation, but after 75 d PUN concentrations between C0 and C123 had decreased (P < .10) by 11%. For C247, PUN concentrations after 27 and 75 d of corn supplementation had decreased (P < .10) by 17 and 18%, respectively, compared with C0. Plasma urea N concentrations increased (P < .01) linearly (r2 = .93) with an increase in digestible CP:DE ratio (DP:DE).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Appalachian Soil and Water Conservation Research Laboratory, ARS, USDA, Beckley, WV 25802-0867.
authors.forename: T P
authors.initials: TP
authors.lastname: Karnezos
authors.forename: A G
authors.initials: AG
authors.lastname: Matches
authors.forename: R L
authors.initials: RL
authors.lastname: Preston
authors.forename: C P
authors.initials: CP
authors.lastname: Brown
mesh_terms: D000821:Animal Feed; D000818:Animals; D001806:Blood Urea Nitrogen; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D004435:Eating; D002149:Energy Intake; D005527:Food, Fortified; D008297:Male; D008460:Meat / Q000592:standards; D000455:Medicago sativa; D011897:Random Allocation; D012756:Sheep / Q000097:blood / Q000254:growth & development*; D015430:Weight Gain; D003313:Zea mays
chemical_list: D004044:Dietary Proteins