Sheep grazing behavior as affected by supplementation

Abstract

Behavioral characteristics of supplemented (S; 23% crude protein, 3.41 mcal DE/kg) and nonsupplemented (N) ewes grazing native New Mexico rangeland were monitored from December 1983 to August 1984. Four marked ewes were observed per treatment group. Behavioral data wera collected by simutaneous observations of both treatment groups by 2 observers starting 0.5 hour before sunrise, and continuing until 0.5 hour after sunset. Trials were conducted during the winter breeding season while ewes grazed dormant forage, during spring lambing that coincided with the onset of active forage growth, and during summer lactation, during both a quiescent period and active forage growth. Supplement was not fed during the summer. Total grazing (min/- day) was less (P=0.01) in winter, equal in spring, and greater (P=0.01) in summer for S than N ewes. Mean daily periods of loafing for S ewes was greater (P=0.01) in winter; equivalent in spring, and less (P0.01) in summer than for N ewes. Daily travel time did not differ between S and N ewes during the winter; however, S ewes traveled more (P=0.02) in spring and less (P=0.01) in summer than N ewes. Supplemented ewes tended (P=0.06) to weigh less after the winter breeding season, and weaned similar, but slightly heavier, lambs (P=0.14) than N ewes. There were no differences (P>0.22) in ewe live weights during the remainder of the study. Mean fleece weights were not different (P=0.52) between S and N ewes. Supplemental feeding of range ewes, under the conditions of this study, did not appear to improve overall production by S ewes. Slower weight gains for S ewes during breeding may have resulted from reduced grazing time noted for this period.