Combined effects of VFA composition of rumen fluid and heat exposure on rumen fermentation characteristics and tissue responsiveness to insulin in sheep: Practical application on the intragastric continuous infusion of VFA-TG and casein solutions

Hong, K.S.; Chung, T.Y.; Sano, H.; Shiga, A.; Nakashima, Y.; Ambo, K.

Korean Journal of Animal Nutrition and Feedstuffs 21(3): 271-284

1997


Accession: 008344853

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Abstract
This study was conducted to investigate the combined effects of VFA composition of rumen fluid and heat exposure (30 +- 2 degree C) on the rumen fermentation characteristics and dynamic aspect of blood glucose metabolism in sheep. The total infusion of nutrients was examined in sheep via the technique of continuous alimentation. Four adult Suffolk sheep fitted with a permanent ruminal cannula and a simple T-shaped duodenal cannula were used. A peristaltic pump was used to infuse solutions of volatile fatty acid triglycerides (VFA-TG, triacetin:tripropionin:tributyrin) consisting of 70:20:10 (low propionin division: LP) and 50:40: 10 (high propionin division: HP) on the basis of energy and minerals into the rumen, and casein solution into the duodenum. The results obtained are summarized as follows: 1. Ruminal total volatile fatty acid (VFA) concentration tended to be higher in the heat exposure than in the thermoneutral environment, but had no significant difference between the levels of VFA-TG solutions (LP and HP division). 2. Molar percent of acetate was higher (P lt 0.01), and molar percent of propionate and butyrate were lower (P lt 0.01, P lt 0.05) in the heat exposure than in the thermoneutral environment. The results indicated that the ratio of acetate to propionate (A:P ratio) increased (P lt 0.01) in the heat exposure than in the thermoneutral environment, and in the LP division than in the HP division (P lt 0.01). 3. Infusion of VFA-TG into the rumen caused a marked increase in ruminal TG concentration and a slight decline in ruminal pH values during the heat exposure (latter half of the infusion period). 4. In the hyperinsulinemic euglycemic clamp (EGC) technique, the responsiveness of peripheral tissues to insulin were slightly higher in the heat exposure than in the thermoneutral environment, but had no significant difference between the levels of VFA-TG solutions.