Intake, digestion, and nitrogen and sulfur retention in Angora goats and Merino sheep fed herbage diets

Abstract

The voluntary intake and digestion of three pasture hays of varying quality by Angora goats was compared with that by Merino sheep. The excretion and retention of nitrogen and sulfur were also measured. When a high quality hay was given, there were no differences between goats and sheep in the intake of organic matter (68 vs 61 g/kg0.75.d) or in organic matter digestibility (digestible organic matter intake) (72 vs 7 1 %). However, the goats appeared to utilize nitrogen less efficiently than the sheep as evidenced by nitrogen retention (673 vs 794 mg/100 g digestible organic matter intake.d), and there was a tendency for sheep to use absorbed energy more efficiently for body tissue synthesis. The apparent digestion of organic matter (65 vs 57%), plant cell wall constituents (67 vs 59%), nitrogen (29 vs 19%) and sulfur (40 vs 33%) in a medium quality hay low in nitrogen was greater in goats than in sheep. There were no differences in intake, but the goats were more efficient at conserving nitrogen (nitrogen retention -87 vs -200 mg/ 100 g digestible organic matter intake.d). Similar trends occurred when a poor quality hay with a higher nitrogen content was given. Goats have apparent advantages over sheep in their ability to digest fibrous feeds and conserve limiting nutrients from such feeds. Consequently, they may require less supplementary feeding than sheep in temperate areas during late summer and autumn when animals graze mature pastures.