Effects of a high protein starter diet with fermented soybean cake on growth performance of organic pigs weaned outdoor

Weaners have a great genetic potential for growth, which currently are not fully utilized in the organic pig production under European conditions, characterized by prolonged lactation period, access to roughage and a limited range of feedstuff available as compared to conventional pig production. Nutrition is a key element for improving the growth and utilization of nutrients, however, is also a risk factor for post-weaning diarrhea. The objective of this study was to investigate the effect of a starter diet, with a high content of dietary protein and including fermented soybean cake, on the growth performance of organic pigs weaned outdoors. In total, 600 organic pigs weaned at d 49 on average were included in the study. The study comprised of five outdoor feeding trials lasting 46 d on average. The initial 14 d, pigs were fed an organic standard starter diet (control (n = 5); 134 g standardized ileal digestible crude protein/kg) using toasted soybean cake as the main protein source or high protein starter diet (HP (n = 5); 167 g standardized ileal digestible crude protein/kg) using fermented soybean cake as the main protein source. After 14 d the dietary differentiation ceased, and the pigs were offered a standard organic grower diet. Initial and final bodyweight and feed consumption were recorded at paddock level and diarrhea traits were visual assessed during the feeding trial. Pigs fed control starter diet had a 3% greater average daily feed intake compared to pigs fed HP starter diet (P = 0.022). Moreover, the average daily gain was increased by 8% (P = 0.013) and the feed conversion ratio was improved by 12% (P = 0.001) when pigs were fed the HP diet as compared to the control diet. The improved feed efficiency of pigs fed the HP diet, improved the calculated N efficiency and reduced the estimated N excretion per produced pig. In spite of the high protein content of the HP starter diet, the subjective diarrhea evaluation did not indicate increased risk of developing post-weaning diarrhea. In conclusion, organic pigs weaned outdoor benefitted from being fed a starter diet high in protein using fermented soybean cake as the major protein source. Growth performance was improved, without indication of increased risk of developing post-weaning diarrhea.