INFLUENCE OF TYPE OF FEEDING AND RUMEN INCUBATION-TIME ON IN SACCO DRY-MATTER DEGRADABILITY OF RYEGRASS, STRAW AND CONCENTRATE IN SHEEP AND GOATS

Four each, male, rumen fistulated sheep and goats were fed different types of diets in a Latin-square design: (1) 100% artificially dried ryegrass; (2) 50% artificially dried ryegrass, 50% wheat straw; (3) 33% artificially dried ryegrass, 33% wheat straw, 33% concentrates; and (4) 33% wheat straw, 67% concentrates. Sheep consumed 1200 g of feed per day, goats 75% of this level. After 22 days of feeding, nylon bags of artificially dried ryegrass, wheat straw and concentrate were incubated for 6, 12, 24, 48 and 72 h in the rumen of all animals to measure the in sacco dry matter degradability (DMD). Samples of rumen liquor were taken via rumen fistula at the end of each feeding period (day 25). Concentration of volatile fatty acids (VFA) was determined by gas chromatography. In sacco DMD was significantly influenced by incubated feeds and incubation time. Type of feeding influenced only straw DMD (means: (1) 37.3; (2) 41.2; (3) 40.2; (4) 37.0%). Sheep and goats showed no significant differences of DMD (overall means: ryegrass - sheep, 81.4; goats, 81.7; straw - sheep, 38.5; goats, 39.4; concentrate - sheep, 88.8; goats, 88.4%). DMD of sheep and goats was highly correlated (r=0.99). Total concentration of VFA of rumen liquor was higher (9.8 to 7.0 mmol/100 ml) and the pH was lower (6.33 to 6.45) in sheep than in goats. Molar concentration of VFA was not significantly influenced by animal species. Results demonstrated no important difference in rumen processes between sheep and goats.