TROPICAL PASTURE HAY UTILIZATION WITH SLAFRAMINE AND COTTONSEED MEAL - RUMINAL CHARACTERISTICS AND DIGESTA PASSAGE IN WETHERS

Sixteen mature, ruminally cannulated wethers (average BW = 41 +/- 1 kg ) were fed a low-quality hay diet with or without a cottonseed meal (C SM) supplement and the parasympathomimetic agonist slaframine (SF). Tr eatments were basal diet (Mitchell grass hay, 4.8% CP, 46.8% ADF) avai lable on an ad libitum basis, basal diet plus SF (8 mug/kg BW, 2 x dai ly i.m. injection), basal diet plus CSM (41.0% CP; 100 g/d), or basal diet plus SF and CSM. Treatments were arranged as a 2 x 2 factorial wi thin a replicated 4 x 4 Latin square with 20-d periods followed by a 1 0-d adjustment during which only the basal diet was fed. All measureme nts were performed within the final 10 d of each period. Slaframine in creased salivary flow by 10 to 35% (P < .07), ruminal fluid dilution r ate by 8 to 11% (P < .10), and pH by 3 to 4% (P < .001). A twofold inc rease (P < .05) in ruminal cellulolytic bacteria numbers occurred in S F-treated wethers. Despite these SF-induced changes in the ruminal env ironment, whole-tract apparent nutrient digestibility, N and mineral b alance, and ruminal VFA concentrations were not changed. Cottonseed me al increased forage intake by 34 to 54% (P < .001) and DM digestibilit y by 30% (P < .001). Cottonseed meal supplementation of a Mitchell gra ss hay diet improved nutritional status and attenuated live weight los s.