The effects of different methods of estimating fecal output on plasma cortisol, fecal output, forage intake, and weight change in free-ranging and confined wethers.

Thirty-four white-face wethers (avg BW 56 kg) were used in two experiments to investigate differences in plasma cortisol, forage intake, fecal output, and BW change associated with two methods of estimating fecal output. The methods were fecal collection bags (B) and marker estimates of fecal output (U). A control treatment (C) was included in each experiment in which wethers were not bagged or dosed with the marker. Experiment 1 was conducted with wethers grazing dormant sagebrush-bunchgrass range. Experiment 2 was conducted with wethers housed in metabolism crates. In Exp. 1, the following differences were detected: 1) basal and mean integrated (following ACTH challenge) plasma cortisol levels were higher (P < .05) for U wethers than for C wethers, 2) no differences (P > .05) between B and C wethers were detected for basal or mean integrated plasma cortisol, 3) both B and U wethers gained (P < .05) weight, whereas C wethers lost weight, and 4) no differences (P > .05) between B and U wethers were detected for cortisol measurements, weight change, or fecal output. No differences (P > .05) were noted for any of the variables tested in Exp. 2. When treatments were combined within experiment to test Exp. 1 vs 2, time to peak cortisol levels was longer (P < .05) and mean integrated cortisol levels and weight change were lower (P < .05) for wethers in confinement than for wethers on range. No difference (P > .05) was detected for basal cortisol levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of barley variety and restricted versus ad libitum intake on rate, site, and extent of digestion by wethers fed a high-energy diet.

Twelve ruminally cannulated wethers (four with duodenal cannulas) were used in a replicated 4 x 4 Latin square to investigate effects of barley variety and restricted vs ad libitum intake on site, rate, and extent of digestion. Diets were based on Ottus (52.7% starch; O) or Steptoe (56.7% starch; S) barley fed at either 90% of prestudy ad libitum feed intake (R) or ad libitum consumption (A). Diets were formulated to be equal in starch content (38%). Periods consisted of 10 d for adaptation followed by 10 d in which fecal, duodenal, ruminal, and in situ collections were made. With the exception of ruminal starch digestion, barley variety did not interact with level of feed intake (P > .26). Intake of OM was 1,009, 996, 1,124, and 881 g.wether-1.d-1 for O, S, A, and R, respectively. Intake by R wethers of OM and starch was 78% (P < .01) of intake by A wethers. Duodenal flow of OM and ruminal pH were not affected (P > .28) by either intake restriction or barley variety. Although restricted intake did not affect ruminal (P = .84) and duodenal (P = .39) ammonia nitrogen, the O barley had higher (P = .01) ruminal and duodenal ammonia nitrogen than did S barley. Restricted intake had no effect (P > .30) on rate of ruminal barley digestion, ruminal and total tract starch digestion, or total tract OM digestion. This may be due to the rapid digestion rate of barley.(ABSTRACT TRUNCATED AT 250 WORDS)