Evaluating seasonal serum vitamin D levels and growth performance in pigs from organic farms

Summary

Vitamin D is an essential micronutrient in pig production as it plays an important role in many physiological functions. The aim of this study was to determine serum vitamin D concentration and growth performance in pigs reared on organic farms in different seasons. A total of 109 Krškopolje pigs were selected for this study. Pigs were divided into three groups: low altitude outdoor group A (N = 39), high altitude outdoor group B (N = 36) and indoor group C (N = 34). Blood samples and body weights were collected seasonally in 2022 and 2023. Serum vitamin D levels peaked in summer for outdoor groups A (69.3 ±2.6 ng/ml) and B (65.3 ±4.4 ng/ml) and were the lowest in winter (group A 21.5 ±2.2, group B 35.2 ±2.5). Altitude had no significant effect on vitamin D levels except in winter (p<0.001). Housing type significantly influenced vitamin D levels in every season between groups B and C, and in spring, summer, and autumn between groups A and C. Pigs in the outdoor group A showed higher average final body weights (151.2 ±7.5 kg in 2022 and 146.8 ±3.8 kg in 2023) than those in group C (132.7 ±11.3 kg and 118.5 ±6.9 kg), though this should be interpreted cautiously given variability in initial weights.