Internal Markers For Predicting Dry Matter Intake And Digestibility In Santa Ines Ewes On A Pasture

Assessing feed intake is a valuable tool for herd management decisions. The use of markers is one of the most widely used techniques for estimating dry matter intake (DMI) in ruminants. Thus, internal markers (IM) were evaluated to predict DMI and digestibility (DMD) in ewes supplemented on a pasture during pre- (75, 105 and 135 days of gestation) and postpartum periods (30 and 60 days of lactation). The animals were kept on a pasture, and they were put into individual stalls to receive their supplementation. Twelve ewes were distributed in a completely randomized design: (a) Two supplementation levels (SL; 5 and 15 g/kg body weight, BW) and three IM (indigestible neutral detergent fiber, iNDF; indigestible acid detergent fiber, iADF; and rumen-undegradable dry matter; RUDM) were used and analyzed as mixed models. (b) The DMI and DMD, which were estimated by the best marker, were analyzed as repeated measures using the mixed procedure in SAS. Fecal output was estimated using an external marker (LIPEA (R); isolated, purified and enriched lignin). The DMI and DMD estimated by RUDM were greater and better than iADF and iNDF, which were similar. The effects of SL and physiological stages for DMI and DMD were evaluated by the values obtained from RUDM. As expected, regardless of the physiological stage, DMI and DMD were greater in the animals that received 15 g/kg BW. Considering the physiological stage, the animals fed 15 g/kg BW had greater DMI and DMD at 75 days of gestation and 30 days of lactation and the least DMI was observed at 135 days of gestation and 60 days of lactation. In conclusion, RUDM provides the best estimates for DMI and DMD, which were greater in animals receiving 15 g/kg BW of concentrate at the beginning of gestation and lactation.