RESUMO
The importance of intestinal alkaline phosphatase (IAP) in maintaining gut health and intestinal homeostasis is well established. The objective of this study was to investigate the tolerance of poultry and swine to dietary supplementation of a novel microbial-derived alkaline phosphatase (AP; E.C. 3.1.3.1 produced by Paenibacillus lentus strain CMG3709). Studies were conducted on day-old Ross 308 chicken (n = 1,000; Study 1) and weaned piglets (n = 180; Study 2) for a duration of 42 d; and consisted of four treatment groups (TG) based on the concentration of microbial-derived AP supplemented in their diet at 0; 12,000; 20,000; and 200,000 U/kg of feed. Parameters such as animal survival, hematology, coagulation, and biochemical indices were assessed at the end of the study. The effect of microbial AP on nutrient absorption through skin pigmentation and intestinal permeability were also investigated in broilers (n = 600; Study 3). In poultry (Study 1), there were no statistically significant differences between control and TG for any of the hematological and biochemical parameters, except for a marginal increase (P < 0.05) in serum phosphorus at the highest dose. This variation was not dose-dependent, was well within the reference range, and was not associated with any clinical correlates. In swine (Study 2), hematological parameters such as leukocyte, basophil, and lymphocyte counts were lower (P < 0.05) for the two highest doses but were traced back to individual variations within the group. The biochemical indices in piglets showed no significant differences between control and supplemental groups except for glucose (P = 0.0005), which showed a high effect (P = 0.008) of the random blood collection order. Nonetheless, glucose was within the normal reference range, and were not related to in-feed supplementation of AP as they had no biological significance. The survival rate in all three studies was over 98%. Dietary supplementation of microbial-derived AP up to 16.7 times the intended use (12,000 U/kg feed) level had no negative effects in both poultry and swine. In-feed supplementation of microbial-derived AP for 28 d improved intestinal pigment absorption (P < 0.0001) and reduced intestinal paracellular permeability (P = 0.0001) in broilers (Study 3). Based on these results, it can be concluded that oral supplementation of microbial-derived AP is safe for poultry and swine and effective at improving gut health in poultry.
RESUMO
The objective of this study was to evaluate the efficacy of a vaccine in the prevention of Giardia duodenalis infection in calves. Six 2-week old calves were vaccinated subcutaneously with a sonicated G. duodenalis trophozoite vaccine. Six 2-week old control calves received a subcutaneous injection of sterile phosphate-buffered-saline mixed with adjuvant. Injections were repeated after 28 days. Eleven days after the second injection, calves were challenged orally with 1x10(5) purified G. duodenalis cysts from a naturally infected calf. Throughout the study, fecal samples were collected at regular intervals and examined for the presence of G. duodenalis cysts. Blood samples were collected weekly until G. duodenalis challenge and bi-weekly following challenge. Calves were euthanized 14 days after challenge and G. duodenalis trophozoites within the small intestines were enumerated. Serum antibody titers were significantly higher in vaccinated compared to non-vaccinated calves. Vaccinated calves tended to excrete more G. duodenalis cysts in their feces than non-vaccinated calves. The number of trophozoites in the small intestine was not different between vaccinated and non-vaccinated calves. Changes consistent of moderate enteritis were found in the intestines of one vaccinated and one non-vaccinated calf. Despite a serological immune response following vaccination, this vaccine was not efficacious in preventing giardiasis or reducing cyst shedding in calves.