Undesirable storage characteristics and changes in nutritive value that occur when alfalfa hay is baled at Conserving hay at moisture concentrations Ͼ200 g kg Ϫ1 is known moisture concentrations Ͼ200 g kg Ϫ1 are well docuto cause spontaneous heating and negative effects on forage nutritive value. While these relationships have been evaluated extensively for mented (Collins et al., 1987;Coblentz et al., 1996). Conalfalfa (Medicago sativa L.), less research has evaluated these factors siderably less information is available concerning storin warm-season grasses, specifically bermudagrass [Cynodon dactylon age characteristics and changes in nutritive value that (L.) Pers.]. In this study, 'Greenfield' bermudagrass was grown on a occur in grass hays, particularly in warm-season grass Pickwick silt loam soil (fine-silty, mixed, semiactive, thermic Typic hays. Reduction of forage nutritive value, primarily in-Paleudult) and packaged in conventional rectangular bales at five duced by microbial activity and the subsequent generaconcentrations of moisture (178, 208, 248, 287, and 325 g kg Ϫ1 ) and Received 26 Oct. 1999. *Corresponding author (coblentz@comp. N expressed on a total N basis; NDSN-DM, neutral detergent soluble N uark.edu). expressed on a total DM basis; NDSN-N, neutral detergent soluble N expressed on a total N basis. Published in Crop Sci

Relatively little is known about storage of wet (>200 g kg−1 moisture) bermudagrass [Cynodon dactylon (L.) Pers.] hay. Our objective was to assess the changes in nutritive value of bermudagrass hay as a function of hay moisture, storage time, and spontaneous heating. ‘Greenfield’ bermudagrass was grown on a Pickwick silt loam soil (fine‐silty, mixed, semiactive, thermic Typic Paleudult) and packaged in conventional rectangular bales at 219, 265, and 302 g kg−1 moisture [low‐moisture (LM), medium‐moisture (MM), and high‐moisture (HM) bales, respectively]. Concentrations of most fiber and fiber‐associated N components increased (P < 0.05) during storage, but these changes occurred primarily during the first 12 d. A nonlinear model Y=α−βnormale−kt2 was used to describe the changes in neutral detergent fiber (NDF), acid detergent fiber, lignin, neutral detergent–insoluble N, and acid detergent–insoluble N (ADIN) during storage. The total changes (β) in NDF were 93.1, 69.5, and 67.8 g kg−1 for HM, MM, and LM bales, respectively. Respective asymptotic maxima for NDF (α) in these treatments were 777, 757, and 739 g kg−1. For ADIN, respective asymptotic maxima (α) reached 3.17, 1.83, and 1.71 g kg−1 for HM, MM, and LM bales, respectively. On Day 65, ADIN exceeded 10% of the entire N pool in both HM and MM bales. The nutritive value of bermudagrass hay baled and stored at >200 g kg−1 moisture deteriorates during storage, and the greatest deterioration occurs during the first 12 d after baling.

Three experiments were conducted to determine the effects of whole cottonseed or cottonseed products on performance and carcass characteristics of beef cattle. In Exp. 1, 120 beef steers (initial BW = 381 +/- 31.7 kg) were fed steam-flaked corn-based finishing diets with 10% (DM basis) basal roughage, and whole cottonseed or individual cottonseed components (cottonseed hulls, meal, and oil). Over the entire feeding period, ADG did not differ (P = 0.95), but DMI increased (P = 0.07) and G:F decreased (P = 0.06) for steers fed the cottonseed diets compared with the control diet. Dressing percent (P = 0.02) and marbling scores (P = 0.02) of carcasses from steers fed the cottonseed diets were less than for steers fed the control diet. In Exp. 2, 150 beef steers (initial BW = 364 +/- 9.9 kg) were used to determine the effects of whole cottonseed or pelleted cottonseed (PCS) on performance and carcass characteristics. Cattle were fed steam-flaked corn-based finishing diets in which whole cottonseed or PCS replaced all of the dietary roughage, supplemental fat, and supplemental natural protein of the control diet. Over the entire feeding period, steers fed the cottonseed diets had lower (P = 0.04) DMI and greater (P < 0.01) G:F than steers fed the control diet. Carcass characteristics did not differ (P = 0.16 to 0.96) among dietary treatments. In Exp. 3, 150 beef heifers (initial BW = 331 +/- 17.1 kg) were used to determine the effects of PCS or delinted, whole cottonseed (DLCS) on performance and carcass characteristics. Heifers were fed rolled corn-based finishing diets in which cottonseed replaced the dietary roughage, supplemental fat, and all or part of the supplemental natural protein of the control diet. Over the entire feeding period, ADG, DMI, and G:F of heifers fed the control diet did not differ (P = 0.19 to 0.80) from those of the cottonseed diets; however, heifers fed the diets containing PCS had greater ADG (P = 0.03) and G:F (P = 0.09) than heifers fed diets containing DLCS. Carcass characteristics of heifers fed the control diet did not differ (P > or = 0.28) from those fed the cottonseed diets. Heifers fed the diets containing PCS had greater (P < or = 0.03) HCW, dressing percent, and LM area than those fed DLCS. Based on our results, whole cottonseed, or products derived from processing whole cottonseed, can replace feedstuffs commonly used in beef cattle finishing diets with no adverse effects on animal performance or carcass characteristics.

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.

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