Metabolic indicators of nutritional stress are not predictive of abnormal oral behavior in piglets

Belly nosing is an abnormal oral-nasal behavior that can develop to high levels in newly weaned piglets and may signal nutritional need. The effects of feed restriction on both behavior and metabolic serum parameters were examined in 128 weaned piglets. All pigs were fed ad libitum during week 1, and during week 2, half of all pens (N=8) were restricted to 65% of ad libitum intake. Blood samples were collected on days 3 and 10 after weaning and behavior was observed from video recordings on days 5 and 12. Piglets were classified as early 'nosers' or early 'non-nosers' based on their behavior on day 5. Feed restriction resulted in elevated non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHB) and both lower glucose and a NEFA/glucose ratio, but belly nosing was not affected. Piglets classified as 'nosers' did not have blood profiles indicating they were in greater nutritional need compared to 'non-nosers' in the first week of weaning, nor did they increase belly nosing or other piglet directed behaviors when restricted in week 2. Overall, no associations were found between blood parameters indicative of nutritional stress and belly nosing. This study identifies serum glucose, BHB and NEFA as well as the glucose/NEFA ratio as useful indicators of nutritional stress in newly weaned piglets.