title: Intake, digestibility, and nitrogen retention by sheep supplemented with warm-season legume haylages or soybean meal.
abstract: The high cost of commercial supplements necessitates evaluation of alternatives for ruminant livestock fed poor quality warm-season grasses. This study determined how supplementing bahiagrass haylage (Paspalum notatum Flügge cv. Tifton 9) with soybean [Glycine max (L.) Merr.] meal or warm-season legume haylages affected the performance of lambs. Forty-two Dorper x Katadhin lambs (27.5 +/- 5 kg) were fed for ad libitum intake of bahiagrass haylage (67.8% NDF, 9.6% CP) alone (control) or supplemented with soybean meal (18.8% NDF, 51.4% CP) or haylages of annual peanut [Arachis hypogaea (L.) cv. Florida MDR98; 39.6% NDF, 18.7% CP], cowpea [Vigna unguiculata (L.) Walp. cv. Iron clay; 44.1% NDF, 16.0% CP], perennial peanut (Arachis glabrata Benth. cv. Florigraze; 40.0% NDF, 15.8% CP), or pigeonpea [Cajanus cajan (L.) Millsp. cv. GA-2; 65.0% NDF, 13.7% CP]. Haylages were harvested at the optimal maturity for maximizing yield and nutritive value, wilted to 45% DM, baled, wrapped in polyethylene plastic, and ensiled for 180 d. Legumes were fed at 50% of the dietary DM, and soybean meal was fed at 8% of the dietary DM to match the average CP concentration (12.8%) of legume haylage-supplemented diets. Lambs were fed each diet for a 14-d adaptation period and a 7-d data collection period. Each diet was fed to 7 lambs in period 1 and 4 lambs in period 2. Pigeonpea haylage supplementation decreased (P < 0.01) DM and OM intake and digestibility vs. controls. Other legume haylages increased (P < 0.05) DM and OM intake vs. controls; however, only soybean meal supplementation increased (P = 0.01) DM digestibility. All supplements decreased (P = 0.05) NDF digestibility. Except for pigeonpea haylage, all supplements increased (P < 0.01) N intake, digestibility, and retention, and the responses were greatest (P = 0.04) with soybean meal supplementation. Microbial N synthesis was reduced (P = 0.02) by pigeonpea haylage supplementation, but unaffected (P = 0.05) by other supplements. Efficiency of microbial protein synthesis was unaffected (P = 0.05) by diet. Ruminal ammonia concentration was increased (P = 0.01) by all supplements, but only soybean meal and annual peanut haylage increased (P < 0.03) plasma urea-N concentrations. Perennial peanut, annual peanut, and cowpea haylages are promising protein supplements for growing lambs.
authors.affiliation: Department of Animal Sciences, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA.
authors.forename: J L
authors.initials: JL
authors.lastname: Foster
authors.forename: A T
authors.initials: AT
authors.lastname: Adesogan
authors.forename: J N
authors.initials: JN
authors.lastname: Carter
authors.forename: A R
authors.initials: AR
authors.lastname: Blount
authors.forename: R O
authors.initials: RO
authors.lastname: Myer
authors.forename: S C
authors.initials: SC
authors.lastname: Phatak
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000818:Animals; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004063:Digestion / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D007887:Fabaceae / Q000378:metabolism*; D005232:Fatty Acids, Volatile / Q000032:analysis; D005766:Gastrointestinal Contents / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008297:Male; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism*; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism; D012621:Seasons; D012756:Sheep / Q000378:metabolism / Q000502:physiology*; D013025:Glycine max / Q000378:metabolism*
chemical_list: D005232:Fatty Acids, Volatile; D009584:Nitrogen