Effect of gamma irradiation and autoclaving on sterilization and amino acids digestibility of diets for specific pathogen free mini-pigs containing either soybean meal or whey protein

This study was carried out to evaluate the effects of gamma irradiation and autoclaving on amino acids digestibility of diets for specific pathogen free (SPF) mini-pigs containing either soybean meal or whey protein concentrate. To determine the appropriate dose of gamma irradiation for complete sterilization, 2 experimental diets (soybean meal- and whey protein-based diets) and 3 commercial swine diets were subjected to gamma irradiation with different doses. All the diets were completely sterilized at over 10 kGy dose of irradiation. To compare the effect of sterilization method on amino acid digestion, 2 sterilization methods (gamma irradiation and autoclaving) and 2 dietary protein sources (soybean meal and whey protein) were arranged in a 2×2 factorial to create 4 treatments. Adult SPF mini-pigs with average initial body weight of 25.8±1.4 kg were allocated to treatments with 3 mini-pigs per treatment. Gamma irradiation was executed in a commercial irradiation facility with irradiation dose at 10 kGy. Another portion of diet was autoclaved at 123 °C for 20 min. Both sterilization methods did not induce substantial change in amino acid contents regardless of dietary protein sources. In vitro pepsin+pancreatin digestibilities of CP and DM were greater in irradiated diet than those in autoclaved diet, although the in vitro pepsin digestibility was not different between them. Most of in vivo amino acid digestibilities of irradiated diet were greater than autoclaved diet regardless of protein sources. In addition, the amino acid digestibilities were greater in whey protein diet than soybean meal diet regardless of sterilization method. However, the interaction between sterilization method and protein source was observed on Lys (P=0.027) and Pro (P=0.071) digestibilities. From the results of this study, it could be concluded that gamma irradiation is more favorable than autoclaving for the amino acid digestibilities of both soybean meal- and whey protein-based diets.