Effect Of Yeast Chromium On Production Performance,Lipid Metabolism And Breeding Internal Secretion Of Egg-Laying Specific Hens

This experiment was conducted with HAI-Lanhui egg-laying specific hens to study the effect of yeast chromium adding to diet on production performance, the concentration of insulin lipid metabolism and breeding internal secretion , to determine the best level of yeast chromium during the later period of producing eggs and to discuss the mechanism of its preliminary. 576 HAI-Lanhui egg-laying specific hens of 50 weeks old were assigned randomly into 6 groups each with 3 replicates for a 6 weeks trial. Diets were formulated to meet National Research Council (NRC) requirements for nutrient content. The groups were fed with diets containing 0(control group), 0.2, 0.4, 0.8, 1.0, 2.0mg/kg yeast chromium respectively. The main results showed as follows:㏕he concentration of insulin of HI, IV, Vgroups was obviously higher than the other. ?Dietary yeast chromium did not remarkably influence the average egg weight, feed intake and feed/egg ratio ; but increased egg production ratio of NO. V group compared with control group (P<0.05). At the end of the 6-week experiment, with the change of levels of yeast chromium , there was a increase of egg production ratio in II ,111, IV, V groups compared with control group(P<0.01).While among II .IE,IVgroups ,it showed no difference(P>0.05).NO. V group has extremely significant difference with the other groups(P<0.01).The NO. VI group slightly increased ,but not reached significant level(P>0.05).甌he dietary yeast chromium could also obviously increase the egg breed and hatch-ability . As the experiment was over ,the higher the dietary chromium level were, the high higher of the rate of qualified egg breed .Except for I ,VI groups ,the rest group were extremely significant with the control group(P<0.01).Adding yeast chromium to diet had no effects on spermatization percentage. With the level of chromium increased(from 0.2,0.4,0.8 to 1.0 mg/kg),the hatch-ability of specific hens were increasedin turn .compared with I , VI groups(P<0.05). ?Adding yeast chromium could obviously decrease the mortality and cull rate of all the treatment groups(P<0.01).The 0.4mg/kg group had the lowest mortality and cull rate , but there was no differences among all the treatments.甌he experimental diets had no effect on the cholesterol of egg yolk. It could decrease the serum triglyceride(TG)of all treatments but for II group (PO.05). Serum total cholesterol(TC) decreased also, and in Vas well as VI groups, they had significantly difference with the control group (PO.05), but the rest treatment-group no obviously difference with control group. High density lipoprotein cholesterol (HDL-C) increased 10.17%(P<0.05), 22.51%(P<0.01), 25.42%(P<0.01), 32.63%(P<0.01), while adding 0.4, 0.8, l.Omg/kg yeast chromium to diet , than the control group respectively. The 0.2mg/kg group slightly increased the HDL-C level (P>0.05). ￤ith the amount of yeast chromium increased accordingly ,the difference was significant expect for I and VI groups(P<0.05). It also made the serum progesterone and estradiol level in a upward trend, yet the difference did not reach significant level(PX).05). In conclusion, the diets adding optimal yeast chromium of the specific hens in later egg-laying period ,could slow down the decrease of egg production ratio and qualified egg breed ratio, increased hatch-ability, had good effect on lipid metabolism , promote the excretion of luteinizing hormone . Adding Img/kg yeast chromium to the egg-laying specific hens had the best effect, while 0.4mg/kg additive amount had the best effect on decreasing mortality and cull rate.