370 Effects of the Vasoactive Intestinal Polypeptide (VIP) for the Efficient Ruminant Product

Abstract

Abstract Feeding high-grain diets can result in reduced ruminal pH, inflammation of ruminal and other tissues, and subacute ruminal acidosis. Vasoactive intestinal polypeptide (VIP), a gut hormone with anti-inflammatory and other functions, could have a beneficial role in ruminants fed high-concentrate diets. To determine the effects of VIP injection on dry matter intake, average daily gain, gain:feed, and ruminal pH, wether lambs (n=16; BW=68.5 ±1.8 kg) were blocked by body weight and randomly assigned to VIP treatment (n=8) or control (n=8). All lambs were housed in individual pens, adapted to the same high concentrate diet (75% whole corn and 25% supplemental pellet; DM basis), and feed intake and average daily gain were measured from day 1 to 21 when lambs were placed in metabolism crates. Lambs in the treatment group were injected intraperitoneally with VIP (1.3 nmol/kg BW in 0.9% NaCl), whereas lambs in the control group were injected with 0.9% NaCl every second day over 28 days. Nutrient balance was measured over the final seven days (data will be reported elsewhere), and lambs then were slaughtered and ruminal fluid and tissues collected. The average daily gain was greater (p = 0.04) in VIP treated lambs than in control lambs. However, no difference (p > 0.05) in daily feed intake was observed between treatments. Ruminal fluid pH was not significantly influenced by treatment (5.2±0.11 vs 5.0±0.11 for the control and VIP treatments, respectively). These data indicate that VIP injection may increase ADG and gain:feed in lambs fed high concentrate diets. Further research is needed to verify these results and to delineate the mechanisms responsible for the observed increases in ADG and gain:feed.