title: Impact of heating-degree-day accumulation during bermudagrass hay storage on nutrient utilization by lambs.
abstract: Spontaneous heating in stored alfalfa (Medicago sativa) has reduced forage quality and DM and N digestibility through microbial respiration and Maillard polymer formation. The impact of heating-degree-day (HDD) accumulation in stored bermudagrass (Cynodon dactylon [L.] Pers.) was evaluated for its effect on nutrient utilization by lambs. Twenty Rambouillet wether lambs (53.1 +/- 0.74 kg) were used in a completely randomized total collection experiment. The hays selected for this study had previously undergone spontaneous heating, producing either 5, 119, 201, 273, or 401 HDD (> 35 degrees C) during a 60-d storage period. Lambs were offered diets of these hays at 1.5% of BW. Dry matter intake did not differ (P = 0.59) among hays. Linear relationships were detected between HDD and apparent digestibilities of DM (y = 59.1 - 0.016x; P < 0.01; R2 = 0.37), OM (y = 59.3 - 0.017x; P < 0.01; R2 = 0.43), NDF (y = 66.4 - 0.012x; P = 0.01; R2 = 0.30), and hemicellulose (y = 74.0 - 0.012x; P = 0.02; R2 = 0.27). Similarly, significant regressions were observed for fecal N excretion (g/d; y = 4.70 + 0.004x; P < 0.01; R2 = 0.68), apparent N absorbed (g/d; y = 7.4 - 0.005x; P < 0.01; R2 = 0.50), apparent N absorption (%; y = 61.2 - 0.038x; P < 0.01; R2 = 0.71), apparent neutral detergent insoluble nitrogen digestibility (%; y = 85.8 - 0.026x; P = 0.01; R2 = 0.73), and apparent acid detergent insoluble nitrogen digestibility (%; y = 1.5 + 0.101x; P < 0.01; R2 = 0.62). Therefore, spontaneous heating during the storage of bermudagrass hay has a negative effect on dry matter and fiber digestion and nitrogen absorption by lambs.
authors.affiliation: Department of Animal Science, University of Arkansas, Fayetteville 72701, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: McBeth
authors.forename: K P
authors.initials: KP
authors.lastname: Coffey
authors.forename: W K
authors.initials: WK
authors.lastname: Coblentz
authors.forename: J E
authors.initials: JE
authors.lastname: Turner
authors.forename: D A
authors.initials: DA
authors.lastname: Scarbrough
authors.forename: C R
authors.initials: CR
authors.lastname: Bailey
authors.forename: M R
authors.initials: MR
authors.lastname: Stivarius
mesh_terms: D000821:Animal Feed; D000818:Animals; D000831:Animals, Newborn; D003902:Detergents; D004043:Dietary Fiber / Q000378:metabolism; D004063:Digestion; D002149:Energy Intake; D005243:Feces / Q000737:chemistry; D005511:Food Handling / Q000379:methods*; D006358:Hot Temperature / Q000009:adverse effects*; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D006109:Poaceae / Q000378:metabolism*; D012756:Sheep / Q000378:metabolism*
chemical_list: D003902:Detergents; D004043:Dietary Fiber; D009584:Nitrogen