Production of fine-wool ewes on yearlong rangeland in West Texas. I. Effects of season, stage of production and supplemental feed on intake.

Effects of season, reproductive stage and supplemental feed on fecal output, forage intake and digestible organic matter intake (DOMI) were determined in fine-wool ewes on rangeland. Fecal output was highest during winter and was not affected by supplemental feed level. Forage intake was similar across seasons, but DOMI was higher during spring because of the higher digestible organic matter (DOM) concentration in the diet. Lactating ewes consumed 35 to 40% more forage and DOM compared with nonlactating ewes. Nonlactating nonpregnant and pregnant ewes had similar intakes. Forage intake and DOMI during summer were intermediate to those observed during winter and spring. Supplemental feed tended to decrease forage intake and slightly increase DOMI, suggesting a substitution effect. It is suggested that intake was limited during winter by maximum passage of undigested residues. Other mechanisms are proposed for limiting intake during spring and summer. Comparison of intake data with National Research Council standards indicates that energy intake was low during most of the year under the conditions of this study.