Feed intake and digestion in the summer and fall by different breeds of ewes consuming forages differing in quality

Sixteen penned, nonpregnant ewes (>3 years of age) of four breed groups (St . Croix, S; St. CroixxTexel, ST; Polypay x Texel, PT; Gulf Coast Native, N) were used in an experiment (west-central Arkansas; 2x4x2 factorial arrange ment of treatments) to determine effects and interactions in feed intake an d digestion of breed group, forage quality (mature bermudagrass, L; late-bo ot endophyte-free fescue, H), and season (summer, S; fall, Fl. Summer tempe rature humidity index [dry bulb temperature + (0.36xwet bulb temperature) 41.2 degrees C] was considerably above and near 72 at 1600 and 0700 hours, respectively. Organic matter digestibility was similar between seasons for H but lower (p<0.05) in the summer vs. fall for L (46.1, 51.7, 61.9, and 62 .3% for L-S, L-E H-S, and H-E respectively; SE 0.98). A comparable interact ion between forage quality and season occurred in digestible OM intake (514 , 607, 878, and 852 g day(-2) for L-S, LF, H-S, and H-F, respectively; SE 2 5.0). Digestible OM intake was similar among breed groups with L but greate r (p<0.05) fur ST and PT than for S and N with H (27.8, 30.3, 30.3, 26.5, 3 9.1, 49.5, 46.7, and 38.7 g kg(-1) BW0.75 for L-S, L-ST, L-PT, L-N, H-S, H- ST, H-PT, and H-N, respectively; SE 1.52). Digestible OM intake differed be tween low and high quality forages more in the summer than fall and varied among breed groups more with high vs. low quality forage; season did not al ter the influence of forage quality on breed group differences. (C) 1999 El sevier Science B.V. All rights reserved.