Objective To investigate the effects of exogenous melatonin (MLT) and lipopolysaccharide (LPS) on the growth performance and immune function of ducks.
Method Eighty 28-day-old healthy Shanma ducks were randomly chosen and divided into four groups including control, MLT, MLT+LPS and LPS groups. The weight and food intake were measured throughout the experimental duration, and on the last day (the 50th day), organism and blood samples were collected to measure biochemical indexes and the levels of growth hormones.
Result Compared with control, LPS impaired growth performance of ducks while MLT had the opposite effect, but the difference was not significant (P>0.05). The levels of insulin-like growth factor and thyroxine in serum declined in LPS group (P>0.05), while the levels of serum growth hormone, insulin-like growth factor and thyroxine increased significantly in MLT group (P<0.05). LPS decreased the thymus index and raised the spleen index significantly (P<0.01). By observing tissue sections, a certain degree of damage was found in thymus, liver and spleen of LPS group, while MLT group had no obvious damage. LPS elevated AST content in serum significantly. MLT significantly lowered AST content (P<0.05) but elevated albumin content in serum (P>0.05).
Conclusion LPS impairs the growth performance and immune function of ducks, and MLT relieves the harmful effects such as slow growth and immunity decline caused by LPS.
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