Effect Of Different Selenium Sources In Broiler Breeders On Growth Performance Of Progeny Broiler And Approach To The Mechanism

This research was conducted to evaluate the effects of different selenium sources on the productive performance of the hens and their offspring, and to approach the mechanism through serum and tissue selenium content, antioxidant function, GSH-Px gene expression, secretion of related hormones, immune indicators and tissue cell morphology.A total of two hundred forty Ling-Nan-Huang breeder hens,39 week of age, were allocated to two treatments, which included three replicates of 40 birds each. The groups were fed the same basal diet (0.04 mg Se/kg) supplemented with 0.30 mg Se/kg of sodium selenite or DL-Selenomethionine. Breeder hens had limited access to feed but ad libitum access to water. The feeding experiment lasted 10 days after 10 days of adaptation period.Total egg numbers were collected and recorded for each replicate everyday and then incubated together as the replicate, respectively. Fifteen eggs per replicate were collected at random and stored at 4℃until divided into egg yolk and egg white for analysis of Se content. The newborn chicks were divided into two groups, which were replicated three times with 60 birds each, were fed the same broiler diet without Se supplement for 56 days. At the beginning and the end of rearing experiment,15 of 1-d-age chicks,4 of 56-d-age broilers and 4 of breeder hens per replicate were randomly selected and slaughtered. Samples were collected and analysed. The main results were as follows:1. Results of feeding experiment indicated that, compared with sodium selenite, DL-selenomethionine increased the birthrate by 7.73%(P<0.05), decreased F/G of the 22-42d,43-56d and 1-56d broilers by 4.96%(P<0.05),9.29%(P<0.05) and 6.72% (P<0.05), and the mortality by 8.34%(P<0.05).2. Results of slaughter experiment indicated that DL-selenomethionine significantly increased the thymus index of 56-d-age broilers by 40.60%(P<0.05), and decreased the drip loss of breast muscle at 48h after slaughter by 0.90%(P<0.05).3. Histomorphometry indicated that, compared with the DL-selenomethionine group, in the sodium selenite group, the shape of liver cells and pancreatic cells shrinked, membrane dissolved mildly, organelle within the cytoplasm reduced, disordering, the nuclear membrane folded, double structure of membrane was not obvious, partial ablation appeared, chromatin marginated and condensed, the mitochondrial swelled, membrane dissoluted, the crest reduced, some crest disappeared, myofilaments were unevenly arranged, fracture appeared, but mitochondria numbers increased.4. Selenium content analysis showed that DL-selenomethionine significant increased Se contents of serum, liver, kidney and muscle in hens,1-d-age and 56-d-age broilers, eggs and thymus in 1-d-age chicks, respectively (P<0.01).5. The antioxidant system function revealed that, for the hens, DL-selenomethionine sifnificantly increased GSH-Px activity of serum, liver, kidney and pancreas (P<0.05), SOD activity of serum and muscle (P<0.05), GSH content of pancreas (P<0.01), T-AOC level of liver and muscle (P<0.05), but decreased MDA content of serum and tissue (P<0.05). For the 1-d-age chicks, DL-selenomethionine improved muscle GSH-Px, SOD and kidney SOD acitivities (P<0.05), muscle and liver T-AOC and kidney GSH level (P<0.01), while decreased muscle and pancreas MDA contents (P<0.05). For the 56-d-age broilers, DL-selenomethionine enhanced serum and muscle GSH-Px activities (P<0.01), serum SOD activity, pancreas and muscle T-AOC levels(P<0.05).6. Hormone and immune indexs showed that there were no significant differences about serum T3, T4, FT3, FT4, IgA, IgG, IgM levels of the broilers.7. The experimental results of the molecular biology revealed that DL-selenomethionine significantly increased the GSH-Px mRNA abundance of pancreas, liver, muscular tissue of the broilers, compared with sodium selenite.Results above suggest that, compared with the sodium selenite, DL-selenomethionine could significantly increase Se content and antioxidant function of breeder hens, improve the egg birthrate, promote the deposition of selenium in offspring tissues and related antioxidant enzyme gene expression and hormone secretion, and enhance the body's antioxidant function, maintain the integrity of cells and improve the health and metabolism of the offspring, finally result in the effects of reducing mortality, advancing feed conversion ratio and improving meat quality.