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The experiment was conducted to investigate the effect of dietary hydroxy-methionine (MHA) chelate supplementation on the production performance, antioxidation performance, immune and reproductive hormone indexes of Xuefeng black bone breeding chickens. A total of 324 healthy 32-week-old Xuefeng black bone chickens with similar body weight were randomly divided into three groups, with six replicates per group and 18 chickens per replicate. The prefeeding period lasted for two weeks and the trial period lasted for eight weeks. The chickens in the control group were fed a basal diet. The experimental groups added 30 mg/kg MHA-Zn (MZ group, calculated by zinc), 25 mg/kg MHA-Mn (MM group, calculated by manganese) and 30 mg/kg MHA-Zn + 25 mg/kg MHA-Mn (MZM group) in the basal diet, respectively. The results showed that compared with the control group, the laying rate and healthy chick rate of the experimental groups were significantly increased (P<0.05). The hatching rate of the MZM group was significantly higher than that of the control group and MM group (P<0.05). The death rate of embryos in the MZ group and MZM group was significantly lower than that in the control group and MM group (P<0.05). The serum content of progesterone, folliclestimulating hormone, estradiol and parathyroid hormone in the MZM group was significantly higher than those in the other groups ( P<0.05). The activity of total superoxide dismutase and catalase in the serum of MZM group was significantly higher than those of the control group and MZ group (P<0.05). The serum activity of manganese superoxide dismutase and glutathione peroxidase in the MZM group was significantly higher than those in the control group and MM group (P<0.05). The serum malondialdehyde content in the MM group and MZM group was significantly lower than that in the control group (P<0.05). Compared with the control group, the content of immunoglobulin A, immunoglobulin M and interleukin-2 in the serum of the MZM group was significantly increased ( P<0.05). The study indicates that adding of MHA chelate in the diet can improve the production performance of Xuefeng black bone chickens by increasing antioxidation performance, immune and reproductive hormone levels. [ABSTRACT FROM AUTHOR]

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of the product TYFER™ (ferric tyrosine chelate) as zootechnical feed additive for chickens, turkeys and minor poultry species for fattening or reared for laying/breeding. The additive is safe for chickens for fattening at the maximum expected level of 200 mg TYFER™/kg complete feed; this conclusion can be extended to chickens reared for laying/breeding and extrapolated to turkeys and all minor poultry species for fattening or reared for laying/breeding. No concerns for consumer safety are expected from the use of the additive in poultry nutrition. The EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) considers that the additive poses a risk to users by inhalation, and should also be considered as an irritant to skin, eyes and mucous membranes. Due to the presence of nickel, ferric tyrosine chelate should also be considered as a dermal and respiratory sensitiser. The supplementation of feed with the additive is not expected to pose an environmental risk. TYFER™ used at the minimum recommended level (20 mg/kg feed) in chickens diets has the potential to improve zootechnical parameters of birds. The additive at 20 mg/kg feed has the potential to reduce the caecal load Campylobacter spp. by at least 1 log10‐units in chickens for fattening, thus with a potential impact to reduce the risk of human campylobacteriosis; however, the Panel notes that the load of Campylobacter in the chickens caecum is one of the multiple factors that contribute to Campylobacter load in carcases‐meat. The conclusions on the efficacy of the additive can be extended to chickens reared for laying/breeding and extrapolated to turkeys and all minor poultry species for fattening or reared for laying/breeding. The Panel recommends including a specification for maximum lithium content in a potential authorisation of the additive. [ABSTRACT FROM AUTHOR]