Stress-Induced Phosphaturia in Weaned Piglets

SIMPLE SUMMARY: The weaning period is a critical period in piglets’ lives. Multiple elements, including diet change, social stress, handling, and change of physical environment, contribute to enormous stress that has health implications. This period has been studied extensively in the past, but some gaps in our knowledge remain. We attempted to fill them by biochemical characterizations of the changes in blood and urine before and after the weaning. The major finding is the observation of the release of phosphate in the urine in the apparent absence of a factor other than weaning. This release is followed by the drop of the phosphate in the blood. Additionally, we observed a population-level Bohr effect, suggesting a decrease in oxygen levels in the tissues. These results point to the development of systemic hypophosphatemia, even though modern diets used in pig breeding have an excess of phosphorus typically. This study sheds new light on the weaning period and will help researchers and veterinary practices in improving design studies and treatments around that time. ABSTRACT: The weaning period in piglets draws significant attention from researchers, veterinarians, and breeders. A substantial change in diet accompanied by enormous stress has health and welfare implications (abnormal feeding intake, infections, umbilical lesions, etc.). While the parameters like optimal age or weight for the weaning have been studied extensively, relatively less attention has been devoted to the study of stress effects in the piglets’ biochemistry. As one of the effects of stress is hyperventilation, a gasometric analysis supported by measurements of hypoxia biomarkers was conducted. Piglets blood and urine, one day and seven days before and one day and seven days after the weaning, were tested. There was no evidence of hyperventilation, but phosphaturia and hypophosphatemia were observed one and seven days postweaning, respectively. A statistical analysis across the population also pointed to minor tissue hypoxia. Our work contributes to an understanding of biochemical dynamics and helps in the interpretation of physiological changes observed in piglets in this critical period.