Nutritional strategies for reducing nitrogen, phosphorus and trace mineral excretions of livestock and poultry

Animal agriculture contributes to environmental pollutions through the surplus nitrogen（N）, phosphorus（P）, and trace minerals that animals excrete. Animal nutritionists have sought alternatives to formulate more efficient diets and reduce production costs and environmental concerns. In general, element excretions may be reduced by avoiding the overfeeding of specific elements or using nutritional approaches to improve element utilizations by the animals. Several nutritional strategies are possible for minimizing N, P, and trace mineral excretions： 1） to accurately meet dietary N, P and trace mineral requirements of animals, which includes reducing the dietary crude protein contents with synthetic amino acids or feeding high rumenally undegraded protein, minimizing the adequate levels of dietary P and trace elements, adopting phase or group-feeding program, and considering the bioavailable trace mineral contents in the feed ingredients; 2） to improve the bioavailabilities of dietary N, P, and trace elements for animals by using some additives（enzymes, growth promoters, probiotics, prebiotics, vitamin D isomers, and organic acids）; 3） to use highly available P sources or organic trace elements. In the future, nutrient strategies must be integrated into total production systems so that animal production systems are environmentally safe as well as economically viable.

The chemical characteristics of different sodium iron ethylenediaminetetraacetate sources and their relative bioavailabilities for broilers fed with a conventional corn‑soybean meal diet

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,the bioavailability of Fe when administered as NaFeEDTA in broilers and other agricultural animals remains untested.Herein,the chemical characteristics of 12 NaFeEDTA products were determined.Of these,one feed grade NaFeEDTA(Qf=2.07×10^(8)),one food grade NaFeEDTA(Qf=3.31×10^(8)),and one Fe proteinate with an extremely strong chelation strength(Fe-Prot ES,Qf value=8,590)were selected.Their bioavailabilities relative to Fe sulfate(FeSO_(4)·7H_(2)O)for broilers fed with a conventional corn-soybean meal diet were evaluated during d 1 to 21 by investigating the effects of the above Fe sources and added Fe levels 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 their 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)with increasing levels of Fe supplementation.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 FeSO_(4)·7H_(2)O(100%)for broilers were 139%,155%,and 166%,respectively.Conclusions The bioavailabilities of organic Fe sources relative to FeSO_(4)·7H_(2)O were closely related to their Qf values,and NaFeEDTA sources with higher Qf values showed higher Fe bioavailabilities for broilers fed with a conventional corn-soybean meal diet.

Dietary manganese supplementation inhibits abdominal fat deposition possibly by regulating gene expression and enzyme activity involved in lipid metabolism in the abdominal fat of broilers

Excessive abdominal fat deposition seriously restricts the production efficiency of broilers.Several studies found that dietary supplemental manganese(Mn)could effectively reduce the abdominal fat deposition of broilers,but the underlying mechanisms remain unclear.The present study aimed to investigate the effect of dietary supplementation with the inorganic or organic Mn on abdominal fat deposition,and enzyme activity and gene expression involved in lipid metabolism in the abdominal fat of male or female broilers.A total of 4201-d-old AA broilers(half males and half females)were randomly allotted by body weight and gender to 1 of 6 treatments with 10 replicates cages of 7 chicks per cage in a completely randomized design involving a 3(dietary Mn addition)×2(gender)factorial arrangement.Male or female broilers were fed with the Mn-unsupplemented basal diets containing 17.52 mg Mn kg^(-1)(d 1-21)and 15.62 mg Mn kg^(-1)(d 22-42)by analysis or the basal diets supplemented with 110 mg Mn kg^(-1)(d 1-21)and 80 mg Mn kg^(-1)(d 22-42)as either the Mn sulfate or the Mn proteinate with moderate chelation strength(Mn-Prot M)for 42 d.The results showed that the interaction between dietary Mn addition and gender had no impact(P>0.05)on any of the measured parameters;abdominal fat percentage of broilers was decreased(P<0.003)by Mn addition;Mn addition increased(P<0.004)adipose triglyceride lipase(ATGL)activity,while Mn-Prot M decreased(P<0.002)the fatty acid synthase(FAS)activity in the abdominal fat of broilers compared to the control;Mn addition decreased(P<0.009)diacylglycerol acyltransferase 2(DGAT2)mRNA expression level and peroxisome proliferator-activated receptor γ(PPARγ)mRNA and protein expression levels,but up-regulated(P<0.05)the ATGL mRNA and protein expression levels in the abdominal fat of broilers.It was concluded that dietary supplementation with Mn inhibited the abdominal fat deposition of broilers possibly via decreasing the expression of PPARγand DGAT2 as well as increasing the expression and activity of ATGL in the abdominal fat of broilers,and Mn-Prot M was more effective in inhibiting the FAS acitivity.

Establishment and evaluation of the primary cultured tibial osteoblast model of broiler chicks

Osteoblasts are considered as a major factor contributing to bone development and mineralization,however,few studies have been done to establish and evaluate the primary cultured tibial osteoblast model of broiler chicks.Therefore,in the present study,two experiments were conducted to establish and evaluate the primary cultured tibial osteoblast model of broiler chicks.In experiment 1,osteoblasts were isolated from the tibia of one-day-old Arbor Acre male broiler chicks using the explant method and identified through the cell morphology,alkaline phosphatase(ALP)and alizarin red staining.Experiment 2 was carried out to evaluate the vitality and mineralization of primary cultured tibial osteoblasts of broilers on days 4,8,12,16,20,24,28 and 32 after incubation,respectively.The results from experiment 1 demonstrated that primary cultured tibial osteoblasts of broilers showed a spindle-shaped,triangular or polygonal morphology.More than 95%of the cells were stained blue-black after ALP staining,and mineralized nodules were formed after 4 days of continuous incubation.In experiment 2,lactate dehydrogenase(LDH)activity stayed at a relatively stabilized level although incubation time affected(P=0.0012)it during the whole culture period.Additionally,incubation time affected(P≤0.0001)the number and proportion of the area of mineralized nodules.They increased linearly and quadratically(P<0.04)with the increase of incubation time,and remained at a stabilized level from 24 to 32 days of incubation.The estimates of the optimal incubation time were 17 and 26 days based on the best fitted broken-line or quadratic models(P<0.0001)of the number and proportion of the area of mineralized nodules,respectively.These results indicate that the primary cultured tibial osteoblast model of broilers has been established successfully by the explant method,and it showed typical osteoblast morphology and characteristics of ALP activity and mineralization,and could maintain a relatively stabilized vitality from 4 to 32 days of incubation;and the optimal incubation time of primary tibial osteoblasts was 17 to 26 days.Therefore,it could be used to further study the underlying mechanisms of bone development and mineralization of broiler chicks.

Effects of dietary graded levels of cinnamon essential oil and its combination with bamboo leaf flavonoid on immune function, antioxidative ability and intestinal microbiota of broilers

Cinnamon essential oil(CEO)and its combination with bamboo leaf flavonoid(BLF)have been shown to exhibit an additive antibacterial effect in vitro,but their functions in broilers were not clear.An experiment was conducted to investigate the effects of dietary graded levels of CEO and its combination with BLF on the growth performance,immune responses,antioxidative ability,and intestinal morphology and microbiota of broilers fed a corn-soybean meal basal diet.A total of 576 1-d-old Arbor Acres commercial male broilers were randomly allotted to 9 treatments with 8 replicates of 8 birds each in a completely randomized design.Birds were fed on a basal corn-soybean meal diet(control,without plant extracts and antibiotics),or the basal diet supplemented with 50 mg of aureomycin kg^-1,50,100,200,400,or 800 mg of CEO kg^-1,a combination of 100 mg of CEO and 16.7 mg of BLF kg^-1,or a combination of 200 mg of CEO kg^-1 and 33.3 mg of BLF kg^-1 for 42 d.Dietary treatment affected(P<0.05)the serum immune globulin M(IgM)contents on d 42,liver malondialdehyde(MDA)contents on d 21,duodenal crypt depth on d 42,relative abundance of Lactobacillus in the cecal contents on d 21,and relative abundances of Escherichia coli and Bifidobacterium in the cecal contents on d 42,but had no effect(P>0.16)on all other measured indices.The addition of 400 mg of CEO kg^-1 or a combination of 200 mg CEO kg^-1 and 33.3 mg BLF kg^-1 increased(P<0.02)serum IgM contents on d 42.Dietary supplementation with 100 or 200 mg CEO kg^-1,or 50 mg aureomycin kg^-1 decreased(P<0.003)liver MDA contents on d 21.In addition,the supplement of 100 mg CEO kg^-1 increased(P<0.002)the Lactobacillus relative abundance in caecum on d 21 and Bifidobacterium relative abundance in caecum on d 42,and decreased(P<0.0001)E.coli relative abundance in caecum on d 42.The results indicated that dietary supplementation with CEO,an alternative to aureomycin,improved the immune status,antioxidantative ability and cecal microbiota of broilers,and dietary supplementation with the combinations of CEO and BLF did not exhibit further effects.Dietary supplementation with 100 mg CEO kg^-1 is beneficial for broilers fed a corn-soybean meal basal diet.

Effectiveness of dietary xylo-oligosaccharides for broilers fed a conventional corn-soybean meal diet

An experiment was conducted to investigate the effect of dietary supplementation of xylo-oligosaccharides（XOS） on growth performance, meat quality, immune functions, duodenal morphology and intestinal microbial populations of broilers fed a conventional corn-soybean meal basal diet. A total of 450 1-day-old commercial Arbor Acres male broiler chicks were randomly allocated by bodyweight to 1 of 5 treatments with 6 replicate cages（15 broilers per cage） for each of 5 treatments in a completely randomized design. Chicks were fed the basal corn-soybean meal diets supplemented with 0, 25, 50, 75, or 100 mg of XOS kg–1 of diet, respectively, for an experimental duration of 42 days. The results showed that supplementation of XOS affected feed conversion rate（feed/gain, F/G） during days 22–42 and 1–42（P〈0.03）, drip loss in thigh muscle（P=0.02）, and duodenal crypt depth（P=0.005） on day 42, but had no effect（P〉0.05） on all other measured indices. The chicks fed the diet supplemented with 100 mg of XOS kg–1 had the lowest（P〈0.05） F/G and drip loss in thigh muscle. The drip loss in thigh muscle decreased linearly（P=0.003） as the supplemented XOS increased. Duodenal crypt depth decreased（P〈0.05） at the supplemental level of 75 mg of XOS kg–1. The results indicate that dietary supplementations of 75 and 100 mg of XOS kg–1 are beneficial to broilers fed a conventional corn-soybean meal diet.

Effects of selenium source and level on growth performance, antioxidative ability and meat quality of broilers

This experiment was conducted to investigate the effects of selenium(Se) source and level on growth performance, carcass traits, antioxidative ability and meat quality of broilers. A total of 320 one-d-old Arbor Acres commercial broilers were randomly assigned to 1 of 5 treatments with 8 replicates in a completely randomized design involving a 2×2 factorial arrangement of treatments plus one Se-unsupplemented basal diet control for 42 d. The two Se sources were sodium selenite and Se yeast, and the two supplemental Se levels were 0.20 and 0.40 mg Se kg^–1. The results showed that broilers fed the Se-supplemented diets had higher(P<0.05) average daily gain and average daily feed intake from 22 to 42 d of age, eviscerated yield and abdominal fat percentages, Se concentrations and glutathione peroxidase(GSH-Px) activities in breast and thigh muscles on d 42, and lower(P<0.05) feed/gain from 1 to 21 and 22 to 42 d of age, mortality from 22 to 42 d of age and malondialdehyde(MDA) concentration in thigh muscle on d 42 than those fed the control diet. Broilers fed the diets supplemented with Se yeast had higher(P<0.05) p H value and lower(P<0.05) shear force in thigh muscle than those fed the diets supplemented with sodium selenite. Additionally, broilers fed the diets supplemented with 0.40 mg Se kg^–1 had lower(P<0.05) shear force in thigh muscle and higher(P<0.05) GSH-Px activities in breast and thigh muscles than those fed the diets supplemented with 0.20 mg Se kg^–1. Furthermore, broilers fed the diet supplemented with Se yeast at 0.40 mg Se kg^–1 had higher(P<0.05) Se concentrations in breast and thigh muscles than those fed the diet supplemented with Se yeast at 0.20 mg Se kg^–1, but no differences(P<0.05) were observed in these indices of broilers fed the diets supplemented with sodium selenite between 0.20 and 0.40 mg Se kg^–1. The results from the present study indicated that supplemental Se could increase the growth performance, muscle Se concentration and antioxidative ability of broilers;and the Se from Se yeast was more effective than the Se from sodium selenite in improving meat quality of broilers.

Effect of in ovo zinc injection on the embryonic development, tissue zinc contents, antioxidation, and related gene expressions of broiler breeder eggs

Two experiments were conducted to investigate the effect of in ovo zinc （Zn） injection on the embryonic development, tissue Zn contents, antioxidation and related gene expressions of fertilized eggs of Arbor Acres broiler breeders. Experiment 1 was conducted to determine an optimal embryonic age for early in ovo injection. A total of 720 fertilized eggs with similar weights were randomly allotted to 4 treatments with 6 replicates per treatment and 30 eggs per replicate in a completely randomized design. The eggs were injected with 0.1 mL sterilized water at 3, 6 and 9 embryonic days of incubation （E3, E6 and E9） or non-injection （the control）, respectively. The results from experiment 1 showed that E3 and E6 injections increased （P〈0.05） the embryonic mortalities, and decreased （P〈0.05） hatchabilities compared to the non-injected control, but no differences （P〉0.05） between E9 injection and the non-injected control were observed in either embryonic mortality or hatchability. The findings suggest that the E9 is the optimal embryonic age for early in ovo injection. In experiment 2, a total of 672 fertilized eggs with similar weights were randomly allocated to 7 treatments with 6 replicates per treatment and 16 eggs per replicate in a completely randomized design. The eggs were injected with 0 （the negative control）, 50, 100, 150, 200, or 250 μg Zn/egg as reagent grade ZnSO4.7H20 in a 0.1-mL solution, or non-injection （the positive control）, respectively at E9-10. The results from the experiment 2 demonstrated that no differences （P〉0.05） among 50 and 100 μg Zn/egg groups and the negative control were observed in the embryonic mortality and hatchability, however, the injection of 200 μg Zn/egg increased （P〈0.05） the embryonic mortality, and injections of 150 and 200 μg Zn/egg decreased （P〈0.05） hatchabilities compared with the controls. The embryonic tibia Zn contents at E20 were increased （P〈0.05） by injections of 150, 200 and 250μg Zn/egg. Zinc injection did not affect （P〉0.05） malonaldehyde （MDA） contents, copper- and Zn- containing superoxide dismutase （CuZnSOD） activities and mRNA expression levels in the liver and heart of chick embryos at E15 and E20. Compared with the negative control, injections of 50, 150 and 200 μg Zn/egg up-regulated （P〈0.05） themetallothionein （MT） mRNA expression levels in the embryonic liver at E20. These results indicated that in ovo Zn injections increased Zn contents in the embryonic tibia and MT mRNA expression levels in the embryonic liver at E20, however, injections of 150-200 μg Zn/egg were harmful to the embryonic development.

Dietary calcium requirements of broilers fed a conventional corn-soybean meal diet from 1 to 21 days of age

Background:The current calcium(Ca)recommendation for broilers is primarily based on studies conducted more than 30 years ago with birds of markedly different productive potentials from those which exist today.And the response indicators in these studies are mainly growth performance and bone ash percentage.Therefore,the present study was carried out to investigate the effect of dietary Ca level on growth performance,serum parameters,bone characteristics and Ca metabolism-related gene expressions,so as to estimate dietary Ca requirements of broilers fed a conventional corn-soybean meal diet from 1 to 21 days of age.Methods:A total of 4201-day-old Arbor Acres male broilers were randomly assigned to 1 of 7 treatments with 6 replicates(10 birds per cage)and fed the corn-soybean meal diets containing 0.60%,0.70%,0.80%,0.90%,1.00%,1.10%or 1.20%Ca for 21 days.Each diet contained the constant non-phytate phosphorus content of about 0.39%.Results:The average daily gain decreased linearly(P<0.001)as dietary Ca level increased.The serum and tibia alkaline phosphatase(ALP)activities,tibia bone mineral density(BMD),middle toe BMD,tibia ash percentage,tibia breaking strength,and tibia ALP protein expression level were affected(P<0.05)by dietary Ca level,and showed significant quadratic responses(P<0.02)to dietary Ca levels.The estimates of dietary Ca requirements were 0.80 to 1.00%based on the best fitted broken-line or quadratic models(P<0.03)of the above serum and bone parameters,respectively.Conclusions:The results from the present study indicate that the Ca requirements would be about 0.60%to obtain the best growth rate,and 1.00%to meet all of the Ca metabolisms and bone development of broilers fed a conventional corn-soybean meal diet from 1 to 21 days of age.

Relative bioavailability of tribasic zinc sulfate for broilers fed a conventional corn-soybean meal diet

An experiment was carried out to investigate the relative bioavailability of tribasic zinc（Zn） sulfate relative to Zn sulfate for broilers fed a conventional corn-soybean meal diet. A total of 504 1-d-old Arbor Acres commercial male chicks were randomly assigned by body weight of birds to one of seven treatments involving a 2×3 factorial arrangement with three levels of added Zn（30, 60, or 90 mg of Zn kg–1） and two Zn sources（tribasic Zn sulfate and Zn sulfate） plus a control with no added Zn for an experimental phase of 14 d. Plasma Zn, tibia ash Zn, pancreas Zn, and pancreas metallothionein（MT） messenger RNA（m RNA） were analyzed at 6 or 14 d of age post-hatching. The results showed that plasma Zn, tibia ash Zn, pancreas Zn, and pancreas MT m RNA increased linearly（P〈0.002） as dietary Zn concentration increased at 6 or 14 d of age. The R2 for a linear model was greater on d 6 than on d 14 for the above 4 responsive criteria, and among these indices, the fitting of the tibia ash Zn concentration was the best（R2=0.99）. Therefore, based on slope ratios from the multiple linear regressions of the above 4 indices of the birds at 6 d of age on daily intake of dietary Zn, the bioavailabilities of tribasic Zn sulfate relative to Zn sulfate（100%） were 95.6%（P=0.18）, 83.5%（P=0.01）, 87.9%（P=0.53）, and 75.9%（P=0.38） for the tibia ash Zn, pancreas Zn, plasma Zn, and pancreas MT m RNA, respectively. The results indicated that generally, Zn from tribasic Zn sulfate was as available as Zn from Zn sulfate for broilers.

Effect of dietary supplementation with flavonoid from Scutellaria baicalensis Georgi on growth performance,meat quality and antioxidative ability of broilers

An experiment was conducted to investigate the effect of dietary supplementation with flavonoid from Scutellaria baicalensis Georgi（SBGFN） as SBGFN-zinc（SBGFN-Zn） on growth performance, meat quality, immune responses and antioxidation of broilers. A total of 450 one-d-old Arbor Acres male broilers were randomly allocated to 5 treatments with 6 replicates of 15 birds per replicate for each treatment in a completely randomized design. Birds were fed a SBGFN-unsupplemented cornsoybean meal basal diet（control） or the basal diet supplemented with 60, 120, 180 or 240 mg SBGFN kg-（–1） from SBGFN-Zn for 42 d. Dietary SBGFN supplementation affected（P〈0.03） drip loss in thigh muscle, total superoxide dismutase（T-SOD） and glutathione peroxidase（GSH-Px） activity in liver of broilers at 42 d of age. Chicks fed the diets supplemented with 120, 180 and 240 mg SBGFN kg-（–1） had lower（P〈0.03） drip loss of thigh muscle than those fed the control diet. Chicks fed the diet supplemented with 180 mg SBGFN kg-（–1） had higher（P〈0.03） liver T-SOD and GSH-Px activity than those fed the diets supplemented with 0, 60 and 120 mg SBGFN kg-（–1）. The results from the present study indicate that dietary supplementation with 180 mg SBGFN kg-（–1） as SBGFN-Zn improved both meat quality and antioxidative ability of broilers.

Effect of dietary supplementation of pyrroloquinoline quinone disodium on growth performance, meat quality and antioxidative ability of broilers

This study was conducted to investigate the effect of dietary supplementation with pyrroloquinoline quinone(PQQ) in the form of PQQ disodium(PQQ·Na2) on the growth performance, carcass traits, meat quality and antioxidative ability of broilers. A total of 720 one-d-old Arbor Acres male broilers were randomly allocated to 1 of 6 treatments with 8 replicates of 15 birds per replicate in a completely randomized design. Birds were fed a PQQ·Na2-unsupplemented corn-soybean meal basal diet(control) or the basal diet supplemented with 0.1, 0.2, 0.3, 0.4 or 0.5 mg PQQ·Na2 kg-1 for 42 d. Compared with the control chicks, the chicks fed the diets supplemented with PQQ·Na2 had lower(P<0.05) feed:gain(F/G) during the grower phase and drip losses of breast muscles on day 42. As supplemental PQQ·Na2 level increased, plasma total antioxidant capacity(T-AOC) on d 42, liver T-AOC on d 21 and heart T-AOC on d 21 and 42 increased linearly(P<0.05), but malondialdehyde concentrations in plasma, liver and heart on d 21 or 42 decreased linearly(P<0.001) or quadratically(P<0.005). The results from the present study indicate that dietary supplemental PQQ·Na2 can improve antioxidant ability and meat quality of broilers, and in general, it is implied that the optimal supplemental PQQ·Na2 level is 0.1 mg kg-1 of diet for broilers from 1 to 42 d of age.

Kinetics of selenium absorption in ligated small intestinal loops of chicks

Selenium(Se)is an essential trace element that has a large number of biological functions for broilers.However,the absorption kinetics of Se from sodium selenite in the small intestine of broilers remains unclear.Therefore,two experiments were conducted with 28-d-old commercial male broilers to study the kinetics of Se absorption in ligated small intestinal segments.In experiment 1,the Se absorption in duodenal,jejunal,and ileal segments at different post-perfusion time points(0,20,40,60,80,100 and 120 min)were compared.In experiment 2,a kinetic study of Se absorption was conducted with the duodenal,jejunal,and ileal loops perfused with solutions containing 0,0.0375,0.075,0.15,0.30,or 0.60μg mL^-1 of Se as sodium selenite,and Se contents in perfusates were determined at 100 min after perfusion.The results from experiment 1 showed that the Se absorption increased in an asymptotic response(P<0.0001)to post-perfusion time within 120 min in all the small intestinal segments,but increased linearly(P<0.0001)at less than 100 min after perfusion in duodenal and ileal segments,while more than 96.0%of the maximum Se absorption occurred at 100 min after perfusion in each small intestinal segment.In experiment 2,there was no difference(P>0.05)in the Se absorption rate among different ligated small intestinal segments perfused with solutions containing 0.0375–0.15μg mL^-1 of Se,however,the Se absorption rate was higher(P<0.05)in the jejunum than that in the duodenum perfused with solutions containing 0.30–0.60μg mL^-1 of Se.The kinetic curves of Se absorption demonstrated that the Se absorption was a saturated carrier-mediated process in the duodenum,and the maximum absorption rate was 1271 pg min^-1 cm^-1;whereas the Se absorptions were a non-saturated diffusion process in the jejunum and ileum,and the diffusive constants were 2107 and 1777 cm2 min^-1,respectively.The results from the present study indicate that the jejunum is the main Se absorption site,and the Se absorption is a saturated carrier-mediated process in the duodenum,but a non-saturated diffusion process in the jejunum and ileum of broilers.

Effect of dietary calcium or phosphorus deficiency on bone development and related calcium or phosphorus metabolic utilization parameters of broilers from 22 to 42 days of age

This experiment was conducted to investigate the effect of dietary calcium(Ca)or phosphorus(P)deficiency on bone development and related Ca or P metabolic utilization parameters of broilers from 22 to 42 days of age based on our previous study,which indicated that dietary Ca or P deficiency impaired the bone development by regulating related Ca or P metabolic utilization parameters of broilers from 1 to 21 days of age.A total of 504 one-day-old Arbor Acres male broilers were randomly assigned to 1 of 4 treatments with 7 replicates in a completely randomized design,and fed the normal control and Ca-or P-deficient diets from 1 to 21 days of age.At 22 days of age,the broilers were further fed the normal control diet(0.90%Ca+0.35%non-phytate P(NPP)),the P-deficient diet(0.90%Ca+0.18%NPP),the Ca-deficient diet(0.30%Ca+0.35%NPP)or the Ca and P-deficient diet(0.30%Ca+0.18%NPP),respectively.The results showed that dietary Ca or P deficiency decreased(P<0.05)tibia bone mineral density(BMD),bone breaking strength(BBS),ash content,tibia ash Ca content and serum P content on days 28 and 42,but increased(P<0.05)tibia alkaline phosphatase(ALP)activity of broilers on day 42 compared with the control group.Furthermore,the broilers fed the P-deficient diet had the lowest(P<0.05)tibia BMD,BBS,ash content,serum P content and the highest(P<0.05)serum Ca content on day 28 compared with those fed the Ca-deficient or Ca and P-deficient diets.The results from the present study indicated that the bone development and related Ca or P metabolic utilization parameters of broilers were the most sensitive to dietary P deficiency,followed by dietary Ca deficiency or Ca and P-deficiency;dietary Ca or P deficiency impaired the bone development possibly by regulating serum Ca and P contents as well as tibia Ca content and ALP activity of broilers from 22 to 42 days of age.

Regulation of bone phosphorus retention and bone development possibly by related hormones and local bone-derived regulators in broiler chicks

Background:Phosphorus is essential for bone mineralization in broilers,however,the underlying mechanisms remain unclear.We aimed to investigate whether bone phosphorus retention and bone development might be regulated by related hormones and local bone-derived regulators in broilers.Methods:Broilers were fed diets containing different levels of non-phytate phosphorus(NPP)0.15%,0.25%,0.35%,0.45% and 0.55% or 0.15%,0.22%,0.29%,0.36% and 0.43% from 1 to 21 or 22 to 42 days of age.Serum and tibia samples were collected for determinations of bone phosphorus retention and bone development parameters,related hormones and local bone-derived regulators of broiler chickens on d 14,28 and 42,respectively.Results:Tibia ash phosphorus,total phosphorus accumulation in tibia ash(TP_(TA)),bone mineral concentration(BMC),bone mineral density(BMD),bone breaking strength(BBS),and ash on d 14,28 or 42,serum 1,25-dihydroxyvitamin D_(3)(1,25(OH)_(2)D_(3))on d 28 and 42,mRNA expressions of tibia fibroblast growth factor 23(FGF23)and dentin matrix protein 1(DMP1)on d 14 and 28 increased linearly or quadratically(P<0.05),while serum parathyroid hormone(PTH)on d 28,tibia alkaline phosphatase(ALP)on d 14,28 and 42,bone gal protein(BGP)on d 14,and mRNA expression of tibia phosphate-regulating gene with homologies to endopeptidases on the X chromosome(PHEX)on d 14 and 28 decreased linearly or quadratically(P<0.04)as dietary NPP level increased.TPTA,BMC,BMD,and ash on d 28 and 42,BBS on d 28,and ash phosphorus on d 42 were positively correlated(r=0.389 to 0.486,P<0.03)with serum 1,25(OH)_(2)D_(3).All of the above parameters were positively correlated(r=0.380 to 0.689,P<0.05)with tibia DMP1 mRNA expression on d 14,28 and 42,but negatively correlated(r=−0.609 to−0.538,P<0.02)with serum PTH on d 28,tibia ALP on d 14,28 and 42,and BGP on d 14.TP_(TA),BMC and ash on d 14 and BMD on d 28 were negatively correlated(r=−0.397 to−0.362,P<0.03)with tibia PHEX mRNA expression,and BMD on d 28 was positively correlated(r=0.384,P=0.04)with tibia FGF23 mRNA expression.Conclusions:These results suggested that bone phosphorus retention and bone development parameters had moderate to strong correlations with serum PTH and 1,25(OH)2D3 and tibia DMP1,PHEX,FGF23,ALP and BGP in broilers during the whole growth period,and thus they might be partly regulated by these related hormones and local bone-derived regulators.

Manganese enhances the expression of the manganese superoxide dismutase in cultured primary chick embryonic myocardial cells

In the present study, the effect of manganese（Mn） on antioxidant status and the expression of the manganese superoxide dismutase（MnSOD） gene in cultured primary myocardial cells collected from the chick embryos was investigated. The hypothesis that Mn supplementation would enhance the expression of MnSOD in cultured primary myocardial cells of chick embryos was tested. Eggs collected from Mn-depleted Arbor Acres laying breeder hens were incubated for 10 days and then myocardial cells were isolated and cultivated for 8 days. The embryonic myocardial cells on day 6 were treated with Mn in the cell culture medium at different time points when the proportion of cells showing spontaneous contraction was over 95% after the 3-day primary culture. A completely randomized design involving a 3 Mn levels（0, 0.5 and 1.0 mmol L^（-1））×3 incubation time points（12, 24 and 48 h） factorial arrangement of treatments（n=6） was used in the current experiment. The results showed that MnSOD activity and m RNA expression level were induced by Mn and increased with incubation time, which supported the hypothesis that Mn would enhance the expression of the MnSOD gene, and thus might protect myocardial cells from oxidative stress during the chick embryonic development.

Regulation of bone phosphorus retention and bone development possibly by BMP and MAPK signaling pathways in broilers

The bone morphogenetic protein(BMP)and mitogen-activated protein kinase(MAPK)signaling pathways play an important role in regulation of bone formation and development,however,it remains unclear that the effect of dietary different levels of non-phytate phosphorus(NPP)on these signaling pathways and their correlations with bone phosphorus(P)retention and bone development in broilers.Therefore,this experiment was conducted to investigate the effect of dietary P supplementation on BMP and MAPK signaling pathways and their correlations with bone P retention and bone development in broilers.A total of 800 one-day-old Arbor Acres male broilers were randomly allotted to 1 of 5 treatments with 8 replicates in a completely randomized design.The 5 treatments of dietary NPP levels were 0.15,0.25,0.35,0.45 and 0.55%or 0.15,0.22,0.29,0.36 and 0.43%for broilers from 1 to 21 days of age or 22 to 42 days of age,respectively.The results showed that extracellular signal-regulated kinase 1(ERK1)mRNA expression in the tibia of broilers on days 14 and 28,phosphorylated-ERK1(p-ERK1)on day 14,and BMP2 protein expression on days 28 and42 decreased linearly(P<0.04),while c-Jun N-terminal kinase 1(JNK1)mRNA expression on day 42 increased linearly(P<0.02)with the increase of dietary NPP level.At 14 days of age,total P accumulation in tibia ash(TP),bone mineral concentration(BMC),bone mineral density(BMD),bone breaking strength(BBS)and tibia ash were negatively correlated(r=-0.726 to-0.359,P<0.05)with ERK1 and JNK1 mRNA as well as p-ERK1;tibia alkaline phosphatase(ALP)and bone gal protein(BGP)were positively correlated(r=0.405 to 0.665,P<0.01)with ERK1 mRNA and p-ERK1.At 28 days of age,TP,BMC,BMD,BBS and tibia ash were negatively correlated(r=-0.518 to-0.370,P<0.05)with ERK1 mRNA and BMP2 protein,while tibia ALP was positively correlated(r=0.382 to 0.648,P<0.05)with them.The results indicated that TP,BMC,BMD,BBS or tibia ash had negative correlations,while tibia ALP and BGP had positive correlations with ERK1 and JNK1 mRNAs,BMP2 protein and p-ERK1,suggesting that bone P retention and bone development might be regulated by BMP and MAPK signaling pathways in broiler chickens.

Effect of the gene silencing of phosphorus transporters on phosphorus absorption across primary cultured duodenal epithelial cell monolayers of chick embryos

The aim of the study was to investigate whether phosphorus(P) transporters, type IIb sodium-dependent phosphate cotransporter(NaP-IIb) and inorganic phosphate transporter 2(PiT2), were directly involved in P absorption across primary cultured duodenal epithelial cell monolayers of chick embryos. The siRNAs against NaP-IIb or PiT2 were designed, synthesized and transfected into primary cultured duodenal epithelial cells of chick embryos. Then, the inhibitory efficiency of siRNAs against NaP-IIb or PiT2 was analyzed, and the most efficacious siRNAs were selected to be used for subsequent P absorption experiments. Briefly, primary cultured duodenal epithelial cells of chick embryos were transfected with either NaP-IIb or PiT2 siRNAs and grown in confluent monolayers on transwell plates. The untransfected or transfected cell monolayers were then incubated in an uptake medium containing 0 or 0.25 mmol L^(–1) of P as KH_(2) PO_(4) to measure the P absorption across duodenal epithelial cell monolayers. The results showed that among the siRNAs designed, si-1372 and si-890 were demonstrated to be the most effective in inhibiting the NaPIIb and PiT2 expressions, respectively. Supplemental P increased(P=0.065) the protein abundance of PiT2 and enhanced(P<0.0001) P absorption in primary cultured duodenal epithelial cell of chick embryos. Furthermore, NaPIIb silencing decreased(P=0.07) P absorption across duodenal epithelial cell monolayers, while PiT2 silencing had no effect(P=0.345). It is concluded that the NaP-IIb, but not PiT2, might be directly involved in the P absorption of chick duodenal epithelial cells.

Dietary copper requirement of broilers fed a corn-soybean meal diet during 22—42 d of age

This research was to assess the dietary copper(Cu)requirement of broiler chickens fed a practical cornsoybean meal diet during 22—42 d of age.A total of 288 numbered Arbor Acres male broilers at 22 d of age were randomly allotted 6 treatments with 8 replicate cages(6 broilers per cage)per treatment.Broilers were fed a Cu-unsupplemented corn-soybean meal basal diet(control,containing 7.36 mg Cu/kg)or the basal diet added with 3,6,9,12,or 15 mg Cu/kg from CuSO_(4)·5H_(2)O for 21 d.Quadratic,asymptotic and broken-line models were fitted and the best fitted models were selected to determine dietary Cu requirements.The results revealed that the contents of Cu in serum and liver,m RNA expression levels of Cu-and zinc-containing superoxide dismutase(CuZnSOD)in liver and monoamine oxidase b(MAO B)in heart,as well as protein expression level of CuZnSOD in liver were affected(P<0.05)by supplemental Cu levels,and the above indices varied linearly and quadratically(P<0.05)with increasing Cu levels.Dietary Cu requirements assessed according to the best fitted broken-line models(P<0.05)of the above indexes were 10.45—13.81 mg/kg.It was concluded that mRNA expression levels of CuZnSOD in liver and MAO B in heart,as well as liver CuZnSOD protein expression level were new specific sensitive biomarkers for estimating dietary Cu requirements,and the dietary Cu requirement was recommended to be 14 mg/kg to support Cu metabolic needs related to key Cucontaining enzymes in broilers fed the corn-soybean meal diet during 22—42 d of age,which was higher than the dietary Cu requirement(8 mg/kg)for broilers at the corresponding stage suggested by the Chinese Feeding Standard of Chicken.

Zinc alleviates the heat stress of primary cultured hepatocytes of broiler embryos via enhancing the antioxidant ability and attenuating the heat shock responses

Zinc(Zn)has been shown to attenuate the adverse effects of heat stress on broilers,but the mechanisms involving this process remain unclear.We aimed to investigate possible protective mechanisms of Zn on primary cultured hepatocytes of broiler embryos subjected to heat stress.Three experiments were conducted.In Exp.1,hepatocytes were treated with 0,50,100,200,or 400μmol/L added Zn as inorganic Zn sulfate(iZn)for 12,24 or 48 h.In Exp.2,cells were exposed to 40℃(a normal temperature[NT])and 44℃(a high temperature[HT])for 1,2,4,6,or 8 h.In Exp.3,cells were preincubated with 0 or 50μmol/L Zn as iZn or organic Zn lysine chelate(oZn)for 8 h under NT,and then incubated with the same Zn treatments under NT or HT for 4 or 6 h.The biomarkers of antioxidative status and heat stress in cells were measured.The results in Exp.1 indicated that 50μmol/L Zn and 12 h incubation were the optimal conditions for increasing antioxidant ability of hepatocytes.In Exp.2,the 4 or 6 h incubation under HT was effective in inducing heat shock responses of hepatocytes.In Exp.3,HT elevated(P<0.01)malondialdehyde content and expressions of heat shock protein 70(HSP70)mRNA and protein,as well as HSP90 mRNA.However,Zn supplementation increased(P<0.05)copper zinc superoxide dismutase(CuZnSOD)activity and metallothionein mRNA expression,and effectively decreased(P<0.05)the ex-pressions of HSP70 mRNA and protein,as well as HSP90 mRNA.Furthermore,oZn was more effective(P<0.05)than iZn in enhancing CuZnSOD activity of hepatocytes under HT.It was concluded that Zn(especially oZn)could alleviate heat stress of broiler hepatocytes via enhancing their antioxidant ability and attenuating heat shock responses.