Effect Of Dietary Supplemented With Polysavone On Laying Traits And Immune Function Of Laying Hens

At present, complicated diseases is one of the important factors which restrict the development of poultry industry in China. Traditional measures of keeping healthy by using veterinary drugs also have some negative effects on intensive farming. Improving the animal immunity and keeping poultry healthy by using the nutrition way is an important measure for the sustainable development of poultry husbandry in China. This experiment was carried out to determine the effect of dietary supplementing with different levels of polysavone on the economic traits and immune functions of laying hens at peak production, and could provide a theoretical basis for the application of polysavone as a dietary feed additive on nutritional immune in laying hens.This test was implemented in a closed hen house with the three-story and stepped hen coops. A total of 540 Nick laying hens with the same average body weight and laying rate at 26 weeks age were randomly assigned into 5 groups with 6 replicates, each replicate had 18 birds. The control group(groupⅠ) was fed with maize-soybean basal diet, while other experimental groups(group Ⅱ ~ Ⅴ) were provided with dietary supplementing with polysavone in basal diet at four level of 300, 600, 900, 1200 mg/kg, respectively. The 77-days experimental period was divided into two phases, including 7-days of pre-experiment and 70-days of experiment. The production performance, egg quality, nutrient utilization and immune indexes were measured.Results:1. Effects of polysavone on laying traits of laying hensDietarysupplemented withpolysavone could improve the laying performance and egg quality of laying hens. The results indicated that the laying rate of group Ⅳ and Ⅴsignificantly increased by 2.65 % and 2.27 % respectively compared with control group(P<0.05). Group Ⅳsignificantly increased average egg weight by 2.58 % compared with control group(P<0.05). The feed/egg ratio was not significant among five groups(P>0.05). Eggshell strength and haugh unit of group Ⅲ significantly increased by 5.10% and 2.28% compared with control group(P<0.05). The group Ⅳ had significant effect on egg weight, eggshell strength, albumen height and haugh unit(P<0.05), which increased by 2.37%, 3.59%, 4.59% and 1.80%, respectively compared with control group(P<0.05). No differences in the egg shape index, eggshell thickness, yolk color and the ratio of egg yolk to albumen were observed among the experimental groups(P>0.05). The group Ⅳ was significantly higher on the apparent metabolic rate of energy, crude protein and calcium, which increased by 7.82%, 9.30% and 9.01%, respectively compared with the control group(P<0.05), but no difference was found among five groups on the apparent metabolic rate of the total phosphorus. Dietary polysavone had no significant effects on body weight, liver, spleen, heart relative index(P>0.05), however, the abdominal fat content significantly decreased(P<0.05).2. Effect of polysavone on immune function of layers(1)Dietarysupplementedwithpolysavonecouldimprovetheserumimmunoglobulinlevels.Th erewasadosageeffectrelationshipbetweenthedietarypolysavonesupplementationandplasmaimm unoglobulin Ig Glevel,thatistosay,themoredietarypolysavonesupplementation,themoreconcentra tionofimmunoglobulin Ig G.Whiletherewasnotadosageeffectrelationshipbetweenthedietarypoly savonesupplementationandplasmaimmunoglobulin Ig Mlevel.(2)Dietary supplemented with polysavone could improve the antibody levels to H9N2(AIV) and NDV, and it also could slow down the decrease in antibody concentrations as time extends.(3) Dietary supplemented with polysavone could promote T lymphocyte transformation rate, but it had no effect on B lymphocyte transformation rate.(4) IL-2 and IL-4 gene expression of chicken spleen in dietary treatment groups were significantly higher than the control group(P<0.05), while the expression of IFN-γ was not different(P>0.05).Conclusions:1. Dietary supplemented with polysavone had significant effects on the production performance and egg quality of laying hens, which may be related to the improvement of utilization efficiency of dietary energy, crude protein, calcium and phosphorus.2. Dietary supplemented with polysavone could significantly improve the immune function of laying hens. It will improve the serum immunoglobulin(Ig G and Ig M) levels, increase the antibody levels to AIV and NDV, slow down the rate of decrease in antibody concentrations, and activate the peripheral blood lymphocytes. What’s more, dietary supplemented with polysavone could increase the gene expression of IL-2 and IL-4 in chicken spleen.