Influence of forage level and naloxone injection on feed intake, digestion, and plasma hormone and metabolite concentrations in dairy heifers.

Four ruminally cannulated Holstein heifers (287 +/- 26 kg) in a 4 x 4 Latin square were used to evaluate the effects of naloxone injection and forage level on dietary intake, ruminal fermentation characteristics, digestibility, and plasma hormone and metabolite concentrations. Treatments were arranged in a 2 x 2 factorial with naloxone injection (0 vs .3 mg/kg; saline vs naloxone, respectively) and forage level (20 vs 100%; concentrate vs forage) as factors. Stanchioned heifers were allowed 21 d for adaptation before a 5-d collection period. Plasma samples were collected several times on d 1 and daily at 0730. Concentrate-fed heifers consumed more feed (P < .10) than forage-fed heifers. Naloxone injection decreased (P < .10) feed intake (grams/kilogram BW) at 1 and 2 h after feeding on d 1. On d 3 at 24 h after feeding, naloxone-injected heifers had increased DM (P < .10) intakes compared with control (saline-injected) heifers. Concentrate-fed heifers had decreased (P < .10) ruminal pH and increased total ruminal VFA concentration. Acetate proportion was decreased (P < .10) and propionate proportion increased in concentrate-fed heifers. Naloxone-injected heifers had decreased (P < .10) total VFA concentrations and increased propionate proportions. Concentrate-fed heifers had greater (P < .10) DM, OM, and CP digestibilities as well as increased plasma (P < .10) insulin, urea N, and glucose concentrations but decreased (P < .10) GH and NEFA concentrations. Naloxone injection increased (P < .10) plasma insulin concentration. Naloxone injection in dairy heifers reduces intake up to 2 h after injection, alters ruminal fermentation patterns, and increases plasma insulin concentration.

Influence of crambe meal as a protein source on intake, site of digestion, ruminal fermentation, and microbial efficiency in beef steers fed grass hay.

Four ruminally and duodenally cannulated beef steers (558 +/- 37 kg) were arranged in a 4 x 4 Latin square to evaluate the influence of crambe meal as a protein source on intake, digestion, and microbial efficiency. Steers were offered chopped (10.2 cm) brome hay (6.2% CP) for ad libitum consumption and one of four supplements. Protein sources used were soybean and crambe meals (CM). Protein sources were blended to provide four levels of supplemental CM protein (0, 33, 67, and 100%). Protein supplements were fed to provide similar amounts of protein and energy. Amounts of supplements fed were 831, 885, 950, and 996 g of DM/steer daily for 0, 33, 67, and 100% CM treatments, respectively. Crambe meal represented 0, 2.00, 3.83, and 5.88% of the DM intake for respective treatments. Steers were allowed a 21-d adaptation to diets before each collection period. Supplements were offered at 0800 and forage at 0830. Crambe meal had no influence (P > .10) on forage and total DM intake (grams/kilogram of BW). Apparent total tract, ruminal, and postruminal digestion of OM, NDF, ADF, and N were unaffected (P > .10) by CM supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)