Dietary Zinc Glycine Supplementation Improves Tibia Quality of Meat Ducks by Modulating the Intestinal Barrier and Bone Resorption.

Leg problems characterized by gait abnormity and bone structure destruction are associated with a high risk of fractures and continuous pain in poultry. Zinc (Zn) acts a pivotal part in normal bone homeostasis and has proven to be highly effective in alleviating leg problems. Therefore, the effects of graded concentration of Zn on bone quality were evaluated in this study. A total of 512 1-d-old male ducks were fed 4 basal diets added 30 mg/kg Zn, 60 mg/kg Zn, 90 mg/kg Zn, and 120 mg/kg Zn as Zn glycine for 35 d. Tibia Zn content, ash percentage, and breaking strength linearly increased with dietary elevated Zn level (P < 0.05). Broken-line analysis revealed that the recommended level of Zn from Zn glycine was 55.13 mg/kg and 64.48 mg/kg based on tibia ash and strength, respectively. To further confirm the role of dietary Zn glycine addition on bone characteristics, data from birds fed either 60 mg/kg Zn as Zn sulfate (ZnSO4), 30 mg/kg Zn, or 60 mg/kg Zn in the form of Zn glycine indicated that birds given 60 mg/kg Zn from Zn glycine diet exhibited higher tibia ash, strength, and trabecular volume compared to those fed the 30 mg/kg Zn diet (P < 0.05). Dietary 60 mg/kg Zn as Zn glycine addition decreased intestinal permeability, upregulated the mRNA expression of tight junction protein, and increased the abundance of Lactobacillus and Bifidobacterium, which was companied by declined the level of inflammatory cytokines in both the ileum and bone marrow. Regarding bone turnover, the diet with 60 mg/kg Zn from Zn glycine induced osteoprotegerin expression and thus decreased osteoclast number and serum bone resorption biomarker levels including serum tartrate-resistant acid phosphatase activity and C-terminal cross-linked telopeptide of type I collagen level when compared to 30 mg/kg Zn diet (P < 0.05). Except for the upregulation in runt-related transcription factor 2 transcription, the experimental treatments did not apparently change the bone formation biomarker contents in serum. Additionally, Zn glycine displayed a more efficient absorption rate, evidenced by higher serum Zn level, and thus had potentially greater a protective role in the intestine barrier and tibia mass as compared to ZnSO4. Collectively, the dietary supplementation of 60 mg/kg in the form of Zn glycine could suppress bone resorption mediated by osteoclast and consequently improve tibial quality of meat ducks, in which enhanced intestinal integrity and optimized gut microbiota might be involved.

Dietary herbaceous mixture supplementation reduced hepatic lipid deposition and improved hepatic health status in post-peak laying hens.

Fatty liver hemorrhagic syndrome is characterized by hepatic damage and hemorrhage impairing animal welfare in birds, which was well-known to be moderately relieved through dietary choline chloride supplementation in laying hens. Chinese herb has been proven to exert a positive role on hepatic health in human and rodents. Here, we investigated the effect of herbaceous mixture (HM), which consists of Andrographis paniculate, Silybum marianum, Azadirachta Indica, and Ocimum basilicum (2:3.5:1:2), on the hepatic lipid metabolism and health status in laying hens. A total of 240 Hy-line Brown hens (389-day-old) were randomly fed the basal diet with 0 mg/kg choline chloride (negative control, NC), 1,000 mg/kg choline chloride (control, Ctrl), or 300 mg/kg HM for 28 d. Birds fed HM diet exhibited lower serum triglyceride (TG) and low-density lipoprotein cholesterol concentration, and higher high-density lipoprotein cholesterol level than those received NC and Ctrl diets (P < 0.05). When compared to control and NC group, the diets with HM decreased the contents of total cholesterol and TG in liver, as well as upregulated the mRNA abundance of hepatic hormone-sensitive lipase and lipoprotein lipase. Meanwhile, the hepatic area and diameter of steatosis vacuoles were also decreased by dietary HM administration (P < 0.05), which accompanied by decreased serum alanine aminotransferase activity (P < 0.05). Birds fed HM diets enhanced the hepatic antioxidative capacity than those received NC and Ctrl diet. Dietary HM depressed the mRNA level of inflammatory cytokine as compared to NC but not Ctrl group. Collectively, the diet with 300 mg/kg HM has a favorable effect in decreasing the lipid deposition and protecting liver injury by alleviating hepatic oxidant stress and inflammation in post-peak laying hens.