INFLUENCE OF ENERGY OR PROTEIN SUPPLEMENTATION DURING MIDPREGNANCY ONFORAGE INTAKE OF EWES GRAZING MONTANA WINTER RANGE

A 2-yr winter experiment was conducted to determine the influence of e ither energy or protein supplementation during midpregnancy on fecal o utput (FO), forage intake, blood metabolite profiles, and BW change of ewes grazing winter range. Thirty-two Targhee ewes were selected for uniformity in age and BW and assigned randomly to one of four dietary treatments 1) no supplement (NONE); 2) 150 g of barley supplement (BAR ); 3) 75 g of feather meal, blood meal supplement (FM/BM); and 4) 75 g of FM, BM, urea supplement (FM/BM/U). Two 5-d experimental periods we re conducted during each winter (January and February). Forage FO (P = .09), total FO (P = .07), and subsequent forage intake (P < .01) were higher during Yr 1 than during Yr 2. Supplement type did not affect fo rage DMI when expressed either as grams/day (P = .57) or as a percenta ge of BW (P = .52). Body weight changes and body condition scores were not affected (P > .10) by year but were affected (P < .01) by treatme nt; unsupplemented ewes lost more (P < .01) BW and body condition than supplemented ewes. Serum urea N (SUN) concentrations were affected(P < .03) by a year x treatment interaction. Unsupplemented, FM/ BM, and FM/BM/U ewes had,higher (P < .10) SUN concentrations during Yr 1 than during Yr 2, averaging 9.8 mg/dL and 7.5 mg/dL, respectively. Barley-s upplemented ewes had similar(P > .10) SUN concentrations both years, a veraging 7.4 mg/dL. Alternate-day supplementation during midpregnancy with energy or protein had no effect on forage DMI of ewes grazing win ter range.