Diurnal Patterns of Ruminal Concentrations and Portal Appearance Rates of Short-chain Fatty Acids in Sheep Fed a Hay or a Concentrate/Straw Diet in Two Meals Daily

Abstract

Three rumen fistulated and catheterized sheep were meal-fed and used to study ruminal and arterial concentrations of short-chain fatty acids (SCFA) as well as portal appearance rates of SCFA and irreversible loss rate (ILR) of acetate in 24 h periods on a hay and a concentrate/straw diet, respectively. Ruminal and arterial concentrations as well as portal appearance rates of SCFA and ILR of acetate were significantly affected by the intake of feed. Generally, the highest concentrations and appearance rates were obtained 2 h after feeding. The portal recovery of arterial acetate was not affected by feeding or diet. The 24 h means were 0.68 ± 0.01 and 0.67 ± 0.01 on the hay and the concentrate/straw diet, respectively. Partial correlation coefficients corrected for the effects of time, sheep, and diet were calculated for the relationships evaluated. The portal appearance rate of acetate (r = 0.52, P r = 0.68, P r = 0.70, P r = 0.22, P r = 0.63, P r = 0.55, P −1, accounted for 44 ± 4 and 43 ± 2% of the calculated metabolizable energy intake on the hay and the concentrate/straw diets, respectively.