Simple methods to estimate the maintenance feed requirement of small ruminants with different levels of feed restriction

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.