Effects of using different sources and levels of zinc on carcass characteristics, tibia bone, serum antioxidant status, meat quality and immune system of broiler chickens

Abstract

Introduction: An experiment was conducted to compare different sources and levels of zinc
on carcass characteristics, tibia bone, serum antioxidant status, meat quality and immune
system on broiler chickens.
Materials & Methods: For this purpose, 480 broilers were selected in a completely
randomized design with a factorial arrangement (4 × 3) with five replications and 8 chicks
were performed in each replicate. Zinc sources included sulfate, oxide and organic complex
of zinc and methionine levels were zero, 60, 120 and 180 mg/kg feed. At the end of the
experiment, the data were analyzed using the GLM procedure of SAS software and the Tukey
test was used to compare the means with a 95% probability level for the main effects (zinc
sources and its levels) and the interactions between them.
Results: The effect of different levels of zinc on weight percentage of spleen, pancreas and
bursa fabricius was significant (P<0.05). The results showed that the effect of source and
level of zinc on serum malondialdehyde was significant; So that the treatment containing
organic sample of zinc had the lowest amount of serum malondialdehyde and also increasing
the level of zinc application in the diet caused a significant decrease in serum
malondialdehyde. Meat moisture in the treatment containing organic zinc sample had a
significant increase compared to oxide treatment, also higher levels of zinc caused a
significant increase in meat moisture (P<0.05). Water holding capacity and pH indices were
not affected by different sources and levels of zinc. As with the results obtained for serum
malondialdehyde, the amount of malondialdehyde in meat was affected by experimental
treatments so that the use of organic zinc sample as well as the use of the highest level of
zinc in the feed (180 mg/kg) significantly (P<0.05) reduced the concentration of
malondialdehyde in meat after slaughter of birds. Different sources and levels of zinc in the
feed had no effect on the trend of changes in the response of the immune titer against gumbo
and bronchitis. At high levels of zinc in the diet, lymphocyte counts decreased and heterophils
increased; Also, the ratio of heterophils to lymphocytes at the level of 180 mg/kg was
significantly higher than the level of 120 mg/kg (P<0.05).
Conclusion: In addition, different sources and levels of zinc and their interactions on the
overall SRBC titer were also insignificant. In general, it can be concluded that regardless of
the type and source of zinc supply, the higher the level of zinc in the diet of broiler chickens
can lead to better retention of zinc in the tibia, the better the quality and durability of the
meat, and the increased immunity of the bird.