| Abstract | Ten Katahdin sheep and ten Spanish goat wethers were used to develop a simple method to estimate dry matter intake (DMI) required for maintenance (DMIm) with feed restriction. Grass hay was fed in a 5-wk Maintenance phase, initially at 51 and 54 g/kg BW0.75 for Katahdin and Spanish, respectively, and then varied by 0-5% every 2-3 days to maintain constant body weight (BW). Individual wether DMIm was the intercept of regressing DMI against BW change in 2- and 3-day periods of wk 3 and 4. In the subsequent 8 wk, wethers consumed hay at 70 or 55% of their Maintenance DMIm. Restricted DMIm was average DMI in wk 8 when no individual wether intercept of regressing BW against day differed from 0. Maintenance DMIm was not influenced by animal type (52.0 and 49.6 g/kg BW0.75 for Katahdin and Spanish, respectively; S.EM. = 0.73). Animal type and restriction level tended (P = 0.084) to interact in Restricted DMIm (34.1, 38.6, 30.7, and 39.0 g/kg BW0.75 for Katahdin-55%, Katahdin-70%, Spanish-55%, and Spanish-70%, respectively; S.E.M. = 1.03), suggesting greater ability of Spanish to lessen energy use with appreciable feed restriction. Correlation coefficients of 0.89, -0.06, 0.96, and 0.85 (P = 0.041, 0.927, 0.009, and 0.066, respectively) between DMIm in the two phases for Katahdin-55, Katahdin-70, Spanish-55, and Spanish-70, respectively, suggest preference for the 55% level for evaluating resilience to feed restriction. In conclusion, frequent determinations of BW and DMI can be used to compare DMIm of individual animals with restricted feeding. |
