Many improvements have been made to bring infant formula (IF) closer to human milk (HM) regarding its nutritional and biological properties. Nevertheless, the protein components of HM and IF are still different, which may affect their digestibility. This study aimed to evaluate and compare the protein digestibility of HM and IF using the infant INFOGEST digestion method. Pooled HM and a commercial IF were subjected to the infant INFOGEST method, which simulates the physiological digestion conditions of infants, with multiple directions, i.e. the curd state, gel images of SDS-PAGE, molecular weight distribution, free amino acid concentrations and in vitro protein digestion rate. HM underwent proteolysis before digestion and tended to have a higher protein digestion rate with finer curds during gastric digestion, than the IF. However, multifaceted analyses showed that the protein digestibility of HM and IF was not significantly different after gastrointestinal digestion. In conclusion, the infant INFOGEST method showed that the digestibility of HM and IF proteins differed to some extent before digestion and after gastric digestion, but not at the end of gastrointestinal digestion. The findings of this study will contribute to the refinement of IF with better protein digestibility in infant stomach.

Female Glossina morsitans morsitans maintained on rabbits previously immunized with whole tsetse body (WTB), engorged tsetse guts (ETG) or gravid tsetse uteri (GTU) for three successive generations showed no increase in mortality. However, a decrease in fecundity which varied with the tissue used as antigen and with the fly generation, was observed. During the three successive fly generations lasting about 4 months, the total decrease in fecundity was approximately 53, 59 and 70% for WTB, ETG and GTU respectively. The total increase in pupal mortality during the first two generations was approximately 7, 19 and 10% for WTB, ETG and GTU respectively, while the corresponding decreases in mean pupal weights were approximately 12, 8 and 11%. Flies fed on rabbits immunized with tsetse salivary glands (TSG), unfed tsetse guts (UTG) and protein extracted from gravid tsetse uteri (GTUP) showed a decrease in fecundity of 20, 26 and 31% respectively during the first fly generation, and a decrease in mean pupal weights of 6, 3 and 8%, while pupal mortalities increased by 38, 26 and 16% respectively.