Our previous study demonstrated that the absorption of zinc (Zn) from the organic Zn proteinate with moderate chelation strength was significantly higher than that of Zn from the inorganic Zn sulfate in the in situ ligated duodenal segment of broilers, but the underlying mechanisms are unknown. The present study aimed to determine the effect of organic Zn with moderate chelation strength and inorganic Zn on the Zn absorption in the small intestine and the expression of related transporters in the duodenum of broilers. The Zn-deficient broilers (13 days old) were fed with the Zn-unsupplemented basal diets (control) containing 25.72 and 25.64 mg Zn/kg by analysis or the basal diets supplemented with 60 mg Zn/kg as the Zn sulfate or the Zn proteinate with moderate chelation strength (Zn-Prot M) for 26 days. The results showed that the plasma Zn contents from the hepatic portal vein of broilers at 28 days and 39 days of age were increased (p < 0.05) by Zn addition and greater (p < 0.05) in the Zn-Prot M than in the Zn sulfate. On d 28, Zn addition upregulated (p < 0.05) mRNA expression of zinc transporter 1 (ZnT1), Zrt-irt-like protein 5 (ZIP5), y + L-type amino transporter 2 (y + LAT2) and b0,+-type amino acid transporter (rBAT), zinc transporter 4 (ZnT4) protein expression, and zinc transporter 9 (ZnT9) mRNA and protein expression in the duodenum. Moreover, ZnT9 mRNA expression, ZnT4, ZIP5, and rBAT protein expression, zinc transporter 7 (ZnT7), and y + LAT2 mRNA and protein expression in the duodenum of broilers on 28 days were higher (p < 0.05) in the Zn-Prot M than in the Zn sulfate. On d 39, supplemental Zn increased (p < 0.05) peptide-transporter 1 (PepT1) mRNA expression and y + LAT2 protein expression, while the mRNA expression of ZnT7 and Zrt-irt-like protein 3 (ZIP3) were higher (p < 0.05) for the Zn-Prot M than for the Zn sulfate in the duodenum. It was concluded that the Zn-Prot M enhanced the Zn absorption in the small intestine partially via upregulating the expression of ZnT4, ZnT7, ZnT9, ZIP3, ZIP5, y + LAT2, and rBAT in the duodenum of broilers.

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Sodium chloride (NaCl) is usually added to diets to meet the Na and Cl requirements of broilers in the Chinese poultry industry, but the optimal dietary NaCl supplemental level was not well-established. The present study was conducted to estimate the optimal dietary NaCl supplemental level of broilers fed a corn-soybean meal diet from 1 to 21 days of age. A total of 490, 1-day-old Arbor Acres male broilers were fed a NaCl-unsupplemented corn-soybean meal basal diet (control) and the basal diet supplemented with 0.10, 0.20, 0.30, 0.40, 0.50 or 0.60% NaCl for 21 days. Regression analysis was conducted to evaluate the optimal dietary NaCl level using the best fitted broken-line or asymptotic models. As dietary supplemental NaCl levels increased, average daily gain (ADG), average daily feed intake (ADFI), blood partial pressure of CO2, total CO2, base excess and anion gap, blood concentrations of HCO3, Na and Cl, serum Na concentration, jejunal villus height (VH) and tibia ash content increased linearly and quadratically (P < 0.05), while feed/gain ratio, relative weights of heart, liver and kidney, blood K concentration, serum concentrations of K, uric acid and glucose, and osmotic pressure decreased linearly and quadratically (P < 0.05). The estimates of optimal dietary NaCl levels were 0.20−0.22% based on the best fitted broken-line or asymptotic models (P < 0.0001) of ADG, ADFI and feed/gain ratio, and 0.08−0.24% based on the best fitted broken-line or asymptotic models (P < 0.0001) of blood gas indices, serum parameters, jejunal VH, tibia ash content and organ indices. These results suggested that the optimal dietary NaCl supplemental level would be 0.24% for broilers fed the corn-soybean meal diet from 1 to 21 days of age, which is lower than the current dietary NaCl supplemental level (0.30%) in the Chinese broiler production.

Background Our previous studies demonstrated that divalent organic iron (Fe) proteinate sources with higher complexation or chelation strengths as expressed by the greater quotient of formation (Qf) values displayed higher Fe bioavailabilities for broilers. Sodium iron ethylenediaminetetraacetate (NaFeEDTA) is a trivalent organic Fe source with the strongest chelating ligand EDTA. However, no study on the bioavailability of Fe as NaFeEDTA in broilers and other agricultural animals has been reported before. Herein, firstly, 12 NaFeEDTA products were collected, and their chemical characteristics were determined. And then, one feed grade NaFeEDTA (Qf value = 2.07 × 108), one food grade NaFeEDTA (Qf value = 3.31 × 108) and one Fe proteinate with an extremely strong chelation strength (Fe-Prot ES, Qf value = 8,590) were selected to evaluate their bioavailabilities relative to Fe sulfate (FeSO4·7H2O) for broilers fed a conventional corn–soybean meal diet during d 1 to 21 by investigating the effects of the above Fe source and added Fe level on the growth performance, hematological indices, Fe contents, activities and gene expressions of Fe-containing enzymes in various tissues of broilers. Results NaFeEDTA sources varied greatly in chemical characteristics. Plasma Fe concentration (PI), transferrin saturation (TS), liver Fe content, succinate dehydrogenase (SDH) activities in liver, heart and kidney, catalase (CAT) activity in liver, and SDH mRNA expressions in liver and kidney increased linearly (P < 0.05) as supplemental Fe levels increased. However, differences among Fe sources were detected (P < 0.05) only for PI, liver Fe content, CAT activity in liver, SDH activities in heart and kidney, and SDH mRNA expressions in liver and kidney. Based on slope ratios from multiple linear regressions of the above indices on daily dietary analyzed Fe intake, the average bioavailabilities of Fe-Prot ES, feed grade NaFeEDTA, and food grade NaFeEDTA relative to the inorganic FeSO4·7H2O (100%) for broilers were 139%, 155%, and 166%, respectively. Conclusions The relative bioavailabilities of organic Fe sources were closely related to their Qf values, and NaFeEDTA sources with higher Qf values showed higher Fe bioavailabilities for broilers fed a conventional corn-soybean meal diet.

Two experiments were conducted to study the effect of bone morphogenetic protein 2 (BMP2) or extracellular signal-regulated kinase 1 (ERK1) silencing on phosphorus (P) utilization and related parameters in primary broiler osteoblasts. Experiment 1 was carried out to select the most efficacious siRNAs against BMP2 or ERK1 for the subsequent experiment. In experiment 2, with or without the siRNA against BMP2 or ERK1, primary broiler osteoblasts were incubated in the medium supplemented with 0.0 or 2.0 mmol/L of P as NaH2PO4 for 12 days. The osteoblastic P utilization and related parameters were determined. The results showed that the si980 and si1003 were the most effective (P &lt; 0.05) in inhibiting BMP2 and ERK1 expressions, respectively. The BMP2 silencing reduced (P &lt; 0.004) the osteoblastic P retention rate, alkaline phosphatase (ALP) activity, BMP2 mRNA and protein expressions. Supplemental P increased (P = 0.0008) ALP activity. Significant interactions (P &lt; 0.04) between the gene silencing and supplemental P level were observed in both mineralization formation and bone gal protein (BGP) content. The BMP2 silencing decreased (P &lt; 0.05) mineralization formation at both 0.0 and 2.0 mmol/L of added P levels, but the decreased degree was greater at 2.0 mmol/L of added P level, while BMP2 silencing reduced (P &lt; 0.05) BGP content at only 2.0 mmol/L of added P level. The ERK1 silencing decreased (P &lt; 0.004) mineralization formation, ALP activity, BGP content, ERK1 mRNA, ERK1 and p-ERK1 protein expressions. Supplemental P increased (P &lt; 0.03) mineralization formation, ALP activity, BGP content and p-ERK1 protein expression, but inhibited (P = 0.014) ERK1 protein expression. There was an interaction (P &lt; 0.03) between the gene silencing and supplemental P level in the osteoblastic P retention rate. The ERK1 silencing decreased (P &lt; 0.05) it regardless of 0.0 or 2.0 mmol/L of added P level, but the reduced degree was greater at 2.0 mmol/L of added P level. It was concluded that either BMP2 or ERK1 silencing suppressed P utilization, and thus either of them participated in regulating P utilization in primary broiler osteoblasts.