Effect of ryegrass hay and ryegrass silage, cut at two stages of development, on nutrient digestibility, nitrogen balance, and purine derivative excretion in growing sheep

Abstract

The objective of this study was to evaluate nutrient digestibility, nitrogen balance, and purine derivative excretion from growing sheep fed on ryegrass silage (S) or ryegrass hay (H) cut at two maturity stages (21 and 35 d). In an in vivo trial, 32 Suffolk × Merino growing sheep (22 ± 2 kg) were used in a completely randomised design with eighth replications in a 2 × 2 factorial arrangement. Four diets were used containing 75% forage (S at 21 or 35 d and H at 21 or 35 d) and 25% concentrate. In an in vitro trial, a completely randomised design was used for gas production parameters. Contents of N and NDF were higher in H (30 and 674 g/kg DM) than in S (26 and 411 g/kg DM). Animals fed on S had higher digestibility (P