The effects of ruminal acidosis on volatile fatty acid absorption and plasma activities of pancreatic enzymes in lambs.

Abstract

Twenty crossbred wethers (41.9 +/- 4.0 kg BW), each fitted with a ruminal cannula and a jugular catheter, were used in a completely randomized design to examine the effects of ruminal acidosis on plasma activities of pancreatic enzymes and fractional rates of VFA absorption. Lambs had ad libitum access to a 50% concentrate diet. Acidosis was induced by an intraruminal dose of glucose at 0, 6, 12, or 18 g/kg BW via the ruminal cannula. Ruminal fluid and plasma were collected 0, 4, 8, 12, 18, 24, 36, 48, and 72 h after dosing. Ruminal fluid pH was reduced (linear, P < .001) with increasing ruminal glucose. Total ruminal VFA concentration decreased (linear, P < .01) and D(-)-lactate (linear, P < .01) and L(+)- lactate (linear, P = .07) concentrations increased with increasing ruminal glucose. Activities of amylase and lipase in plasma were not affected by ruminal glucose (P > .10). Ten days after the acidosis insult, rumens were evacuated and contents were replaced with an isotonic Cr:VFA solution to measure ruminal VFA absorption. Ruminal fluid was collected hourly from 0 to 6 h. Fractional rate of acetate absorption was 13% lower for lambs receiving 18 g/kg BW glucose than for control lambs. In addition, fractional liquid passage rate was lower (P < .05) in lambs receiving 18 g/kg BW glucose 6 mo after the insult of acidosis. These data suggest that a short-term, severe insult of acute acidosis does not result in pancreatic tissue damage but may result in reduced ruminal VFA absorption for an extended period of time.