ABSTRACT
Ten Katahdin (KAT) sheep and 10 Spanish (SPA) 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-week maintenance phase, initially at 51 and 54 g/kg BW0.75 for KAT and SPA, 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 weeks 3 and 4. In the subsequent 8 week, wethers consumed hay at 70% or 55% of their maintenance DMIm. Restricted DMIm was average DMI in week 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 KAT and SPA, respectively; SEM = 0.73). Animal type and restriction level tended (p = .084) to interact in restricted DMIm (34.1, 38.6, 30.7, and 39.0 g/kg BW0.75 for KAT-55%, KAT-70%, SPA-55%, and SPA-70%, respectively; SEM = 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 = .041, .927, .009, and .066, respectively) between DMIm in the two phases for KAT-55, KAT-70, SPA-55, and SPA-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.
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