Effects of the dietary zinc source and vitamin E level on live weight and carcass yield and meat quality in male broilers reared under chronic cyclic heat stress conditions in the finisher phase.

The objective of this study was to evaluate the effect of the interaction of the zinc source (ZnSO4 vs. zinc amino acid complex) and vitamin E level (50 IU/kg vs. 100 IU/kg) on meat yield and quality in broilers subjected to chronic cyclic heat stress in the finisher phase. A total of 1224 one-day-old male Ross 308 broilers were randomly distributed among four dietary treatments. Each treatment contained nine replicates of 34 birds, housed in floor pens in a temperature- and lighting-controlled room. Treatments were organized in a 2 × 2 factorial arrangement: two sources of zinc, 60 mg/kg of Zn as ZnSO4 or 60 mg/kg of Zn as zinc amino acid complexes (ZnAA), combined with two levels of vitamin E (50 or 100 IU/kg). From day 28 until day 37 (finisher phase), all birds were subjected to chronic cyclic heat stress (32 ± 2°C for 6 h daily). In the present study, it was observed that replacing ZnSO4 with ZnAA increased breast meat weight and yield of broilers reared under chronic cyclic heat stress conditions, whereas total slaughter yield was not affected. Moreover, it was observed that replacing ZnSO4 with ZnAA resulted in breast meat with a lower drip and thawing loss and a higher marinade uptake. In conclusion, replacing ZnSO4 with more readily available ZnAA can improve breast meat yield and increase the water-holding capacity of breast meat of broilers exposed to chronic cyclic heat stress at the end of the production cycle. However, as no thermoneutral group was included in the present study, the observed effects of the zinc source cannot be generalized as a solution for heat stress. Moreover, the beneficial effects of ZnAA on breast meat yield and quality seem to be independent of the vitamin E level, and increasing vitamin E level has no additional beneficial effects.

Effect of vitamin E level and dietary zinc source on performance and intestinal health parameters in male broilers exposed to a temperature challenge in the finisher period.

The objective of this study was to evaluate the interaction of zinc source (ZnSO4 vs. zinc amino acid complex) and vitamin E level (50 IU vs. 100 IU) on performance and intestinal health of broilers exposed to a temperature challenge in the finisher period. A total of 1224 day old male Ross 308 broilers were randomly distributed among 4 dietary treatments (9 replicates per treatment). Dietary treatments were organized in a 2 × 2 factorial arrangement: two sources of zinc, 60 mg/kg of Zn as ZnSO4 .7H2 O or 60 mg/kg of Zn as zinc amino acid complexes (ZnAA) combined with two levels of vitamin E (50 or 100 IU/kg). Zinc and vitamin E were added to a wheat/rye-based diet that was designed to create a mild nutritional challenge. From day 28 until day 36 (finisher period), all birds were subjected to chronic cyclic high temperatures (32°C ± 2°C and RH 55-65% for 6 h daily). The combination of ZnAA and 50 IU/kg of vitamin E improved weight gain in the starter (day 0-10), finisher (day 28-36) and overall period (day 0-36) and feed conversion ratio in the starter (day 0-10) and finisher phase (day 28-36). Providing Zn as ZnAA significantly improved villus length and villus/crypt ratio in the starter, grower and finisher period and decreased infiltration of T-lymphocytes and ovotransferrin leakage in the finisher period. In conclusion, providing broilers with a diet supplemented with ZnAA and a vitamin E level of 50 IU/kg, resulted in better growth performance as compared to all other dietary treatments. Interestingly, under the conditions of this study, positive effects of ZnAA on performance did not occur when vitamin E was supplemented at 100 IU/kg in feed. Moreover, providing zinc as zinc amino acid complex improved intestinal health.

Dietary zinc source impacts intestinal morphology and oxidative stress in young broilers.

Zinc is an essential nutritional trace element for all forms of life as it plays an important role in numerous biological processes. In poultry, zinc is provided by in-feed supplementation, mainly as zinc oxide or zinc sulfate. Alternatively zinc can be supplemented as organic sources, which are characterized by using an organic ligand that may be an amino acid, peptide, or protein to bind zinc and have a higher bioavailability than inorganic zinc sources. There are limited number of studies directly comparing the effects of inorganic vs. organic zinc sources on performance and intestinal health in broilers. Therefore, a digestibility and a performance study were conducted to evaluate and compare the effect of an amino acid-complexed zinc source vs. an inorganic zinc source on intestinal health. The experiment consisted of 2 treatments: either a zinc amino acid complex or zinc sulfate was added to a wheat-rye based diet at 60 ppm Zn, with 10 replicates (34 broilers per pen) per treatment. Effects on performance, intestinal morphology, microbiota composition, and oxidative stress were measured. Supplementing zinc amino acid complexes improved the zinc digestibility coefficient as compared to supplementation with zinc sulfate. Broilers supplemented with zinc amino acid complexes had a significantly lower feed conversion ratio in the starter phase compared to birds supplemented with zinc sulfate. A significantly higher villus length was observed in broilers supplemented with zinc amino acid complexes at days 10 and 28. Supplementation with zinc amino acid complexes resulted in a decreased abundance of several genera belonging to the phylum of Proteobacteria. Plasma malondialdehyde levels and glutathione peroxidase activity showed an improved oxidative status in broilers supplemented with zinc amino acid complexes. In conclusion, zinc supplied in feed as amino acid complex is more readily absorbed, potentially conferring a protective effect on villus epithelial cells in the starter phase.

Virulence properties of Campylobacter jejuni isolates of poultry and human origin.

Campylobacter jejuni is one of the leading causes of food-borne gastroenteritis. Because of the high prevalence of C. jejuni in poultry, poultry meat is considered a major source of C. jejuni infections for humans. However, it is not known whether all poultry-associated C. jejuni strains are capable of causing disease in humans. Four different virulence properties of C. jejuni strains were compared between 20 poultry isolates and 24 human isolates. Strains were chosen based on their PFGE pattern to represent a heterogeneous population. The isolates were compared for their ability to invade and induce interleukin-8 (IL-8) production in T84 cells, their production of functional cytolethal distending toxin (CDT) using HEp-2 cells, and their sodium deoxycholate resistance. All four virulence factors were present among strains of human and poultry origin, with strong differences observed among strains. For invasion and IL-8 induction, no difference was observed between the two populations. However, on average, human isolates arrested more HEp-2 cells in their cell cycle than did the poultry isolates (P=0.041), suggesting higher CDT production by the former. The ability to survive 16 000 mug sodium deoxycholate ml(-1) was significantly more pronounced (P=0.006) among human isolates than poultry isolates, although all strains possessed the cmeABC operon. These data suggest that all four virulence properties are widespread among C. jejuni isolates, but that a higher degree of bile-salt resistance and more pronounced CDT production are associated with strains causing enteritis in humans.