Dietary non-phytate phosphorus requirements for optimal productive and reproductive performance, and egg and tibial quality in egg-type duck breeders

Optimal dietary non-phytate phosphorus (NPP) is essential in poultry to maximise productive and reproductive performance, along with indices of egg and bone quality. This study aimed to establish the NPP requirements of egg-type duck breeders aged from 54 to 80 weeks on the following traits: egg production, egg incubation, egg quality, tibial characteristics, reproductive organ, plasma indices, and the expression of genes related to phosphorus absorption. Longyan duck breeders aged 54 weeks (n = 300) were randomly allotted to five treatments, each containing six replicates of 10 individually caged birds. Birds were fed corn-soybean meal-based diets containing 0.18, 0.25, 0.32, 0.38, and 0.45% NPP/kg for 27 weeks. The tested dietary NPP levels did not affect egg production or egg quality indices. The hatchling weight of ducklings increased (quadratic, P < 0.01) as dietary NPP level increased, and the highest value occurred with 0.25% NPP. The number of large yellow follicles (LYF), and the relative weights of LYF and ovary showed linear and quadratic responses to dietary NPP levels; the lowest number and relative weight of LYF occurred with 0.38% NPP, and the lowest ovarian weight was obtained with 0.25% NPP. There were no differences in tibial length, breaking strength, and mineral density in response to dietary NPP levels. In contrast, tibial content of Ca increased (linear, P < 0.01) with dietary NPP levels increasing from 0.18 to 0.45%, and the tibial content of P increased at 0.32% NPP and the higher dietary NPP levels. Plasma concentration of P showed a quadratic (P < 0.05) response to the dietary NPP levels, where the highest value was seen at 0.38% NPP. In conclusion, dietary NPP levels from 0.18 to 0.45% had no effects on egg production, and egg and tibial quality of duck breeders. The duck breeders fed a diet with 0.25% NPP showed the highest hatchling weight of their offspring, while those fed 0.38% NPP had the lowest number and relative weight of LYF. These results indicated that the diet with 0.25% NPP can be used in egg-type duck breeders to improve the hatchling weight of their offspring, without adverse effects on their productivity. The regression model indicated that the maximal hatchling weight of ducklings was obtained from duck breeders fed the diet with 0.30% NPP.

Dietary isoleucine supplementation enhances growth performance, modulates the expression of genes related to amino acid transporters and protein metabolism, and gut microbiota in yellow-feathered chickens

This study investigated the effects of dietary isoleucine (Ile) on growth performance, intestinal expression of amino acid transporters, protein metabolism-related genes and intestinal microbiota in starter phase Chinese yellow-feathered chickens. Female Xinguang yellow-feathered chickens (n = 1,080, aged 1 d) were randomly distributed to 6 treatments, each with 6 replicates of 30 birds. Chickens were fed diets with 6 levels of total Ile (6.8, 7.6, 8.4, 9.2, 10.0, and 10.8 g/kg) for 30 d. The average daily gain and feed conversion ratio were improved with dietary Ile levels (P < 0.05). Plasma uric acid content and glutamic-oxalacetic transaminase activity were linearly and quadratically decreased with increasing dietary Ile inclusion (P < 0.05). Dietary Ile level had a linear (P < 0.05) or quadratic (P < 0.05) effect on the jejunal expression of ribosomal protein S6 kinase B1 and eukaryotic translation initiation factor 4E binding protein 1. The relative expression of jejunal 20S proteasome subunit C2 and ileal muscle ring finger-containing protein 1 decreased linearly (P < 0.05) and quadratically (P < 0.05) with increasing dietary Ile levels. Dietary Ile level had a linear (P = 0.069) or quadratic (P < 0.05) effect on the gene expression of solute carrier family 15 member 1 in jejunum and solute carrier family 7 member 1 in ileum. In addition, bacterial 16S rDNA full-length sequencing showed that dietary Ile increased the cecal abundances of the Firmicutes phylum, and Blautia, Lactobacillus, and unclassified_Lachnospiraceae genera, while decreased that of Proteobacteria, Alistipes, and Shigella. Dietary Ile levels affected growth performance and modulated gut microbiota in yellow-feathered chickens. The appropriate level of dietary Ile can upregulate the expression of intestinal protein synthesis-related protein kinase genes and concomitantly inhibit the expression of proteolysis-related cathepsin genes.

Effects of dietary inclusion of cassava starch-extraction-residue meal on egg production, egg quality, oxidative status, and yolk fatty acid profile in laying ducks

This study was designed to evaluate the effects of different dietary levels of cassava starch extraction residue meal (CReM) on egg production, egg quality, oxidative status, egg yolk fatty acid profile, and hepatic expression of fatty acid metabolism-related genes. In total, 288 Longyan laying ducks aged 21 wk with similar BW were randomly assigned to 4 dietary treatments, each consisting of 6 replicates of 12 birds. The birds were fed a typical corn-soybean meal diet, which contained 0% (control), 5%, 10%, and 15% CReM, mainly replacing wheat bran, and the experiment lasted for 16 wk. The tested CReM levels did not show significant effects on the egg production, nonmarketable egg percentage, egg weight, daily egg mass, and FCR (g feed: g egg), but daily feed intake was reduced with increased CReM level (linear P < 0.001, quadratic P < 0.05). Yolk color increased (linear and quadratic, P < 0.01) with the increase in CReM level, but the Haugh unit, yolk proportion, albumen proportion, shell proportion, eggshell thickness, and eggshell strength were unaffected. Yolk contents of C11:0 and C12:0 (linear, quadratic, P < 0.01) and total saturated fatty acids increased, and the C22:1 level decreased (linear P < 0.01, quadratic P < 0.05) with the increase in CReM level, but the total monounsaturated fatty acids, the individual and total polyunsaturated fatty acids and n−6 and n−3 fatty acids, triglycerides, and total cholesterol in egg yolk were not affected. Hepatic gene expression revealed a significant increase in peroxisome proliferators-activated receptors γ (linear, quadratic, P < 0.001), but the expression of fatty acid synthase, sterol regulatory element binding protein 1 and apolipoprotein A1 genes were unaffected by CReM level. In conclusion, the results of the current study indicated that the CReM could be included up to 15% in laying duck diets without negative effects on the egg-laying rate, egg quality, and oxidative status. Dietary inclusion of CReM increased the yolk content of total saturated fatty acids and SOD activity in the liver.

Effects of maternal and progeny dietary selenium supplementation on growth performance and antioxidant capacity in ducklings

This study evaluated the effects of selenium (Se) supplementation in maternal and offspring diets on performance and antioxidant capacity of ducklings aged from 0 to 2 wk. A total of 144 female Longyan duck breeders aged 22-wk were allotted into 2 treatments and fed a control diet or a 0.16 mg Se/kg supplemented diet. At 40-wk, 120 offspring from each treatment were divided into 2 groups, with 6 replicates of 10 birds. Using a 2 × 2 factorial design, ducklings from each maternal dietary treatment were assigned to a control diet or a 0.16 mg Se/kg supplemented diet from hatch to 2-wk. Compared with Se-deficient diet, maternal diet supplemented with 0.16 mg Se/kg increased the BW of hatchlings (P < 0.01). There were interactions between maternal and progeny diet with 0.16 mg Se/kg in BW of ducklings aged 2 wk and BW gain (BWG) as ducklings from maternal Se/progeny none treatment had the lightest BW and BWG (P < 0.01). Maternal diet with 0.16 mg Se/kg decreased plasma concentration of uric acid and insulin-like growth factor 1 (P < 0.01), and progeny diet supplemented with 0.16 mg Se/kg increased the activities of glutathione peroxidase 3 (GPx3) in plasma and glutathione peroxidase 1 in erythrocyte (P < 0.01). Maternal diet with 0.16 mg Se/kg increased (P < 0.05) the hepatic activity of total superoxide dismutase (T-SOD). Progeny diet supplemented with 0.16 mg Se/kg increased (P < 0.01) hepatic activity of GPx3 and decreased (P < 0.01) the hepatic concentration of malondialdehyde. Interactions were detected between maternal and progeny diet with 0.16 mg Se/kg in hepatic activity of T-SOD and maternal and progeny diet supplemented with Se displayed the highest hepatic activity of T-SOD (P < 0.05). Overall, Se supplementation in the diet of duck breeders and offspring increased the antioxidant capacity of ducklings. Maternal Se supplementation increased the BW of hatchlings, whereas maternal and progeny dietary Se supplementation did not affect the BWG of ducklings aged from 0 to 2 wk. Se supplementation with additional 0.16 mg/kg in the diet of duck breeders and offspring displayed beneficial effects particularly on the antioxidant capacity in ducklings.

[Research on the relationship between V444A mutation of ABCB11 gene and primary intrahepatic stone]

Objective: To investigate the relationship between V444A mutation of the ABCB11 gene and primary intrahepatic stone (PIS). Methods: A total of 164 patients (including 91 males and 73 females, with an average age of (46.0±13.0) years) with PIS and 164 healthy (including 99 males and 65 females, with an average age of (43.8±16.7) years) volunteers were enrolled in this case-control study between October 2017 and June 2019. TaqMan-MGB was used for detecting the V444A polymorphism site of the ABCB11 gene. All the genotypes and allele frequencies were calculated. Pearson chi-squared test was performed to detect the differences in allele and genotype distribution between the two groups. Logistic regression analysis was used to identify genotypes associated with PIS. Results: There was no significant difference in age and gender between the two groups(both P>0.05). The distributions of V444A allele and genotype accorded with Hardy-Weinberg equilibrium law (P=0.161), which indicated that the selected control group represented statistically acceptable sample. Two alleles of T and C, and three genotypes of TT, TC and CC were detected in the locus of V444A. The T and C allele frequencies in the PIS group and the control group were 28.4% vs 35.4%, and 71.6% vs 64.6%, respectively. The frequencies of the T and C alleles were not different between the two groups (P=0.054). The frequencies of TT, TC and CC genotypes in the two groups were 5.5%, 45.7%, 48.8%, and 14.6%, 41.5%, 43.9%, respectively, with significant difference between the two groups (P=0.023). Logistic regression analysis revealed the V444A polymorphism (TC heterozygous mutation) was associated with PIS. Conclusion: ABCB11 gene polymorphism at the site of V444A may be related to the susceptibility of PIS.

Estimation of dietary tryptophan requirement for laying duck breeders: effects on productive and reproductive performance, egg quality, reproductive organ and ovarian follicle development and serum biochemical indices

This study aimed to determine the dietary tryptophan (Trp) requirement for laying duck breeders. A total of 504 Longyan duck breeders (body weight: 1.20 ± 0.02 kg) aged 22 wk were randomly allocated to 6 treatments, each with 6 replicates of 14 ducks. During the next 16 wk, birds were fed the basal diet with total Trp contents of 1.00, 2.00, 3.00, 4.00, 5.00 and 6.00 g/kg, respectively. Dietary Trp levels increased egg production, egg mass and feed intake of duck breeders from 22 to 37 wk (P < 0.05), and there were linear and quadratic effects of Trp level (P < 0.05). The feed conversion ratio (FCR) quadratically decreased with dietary Trp levels (P < 0.05). Dietary Trp levels decreased (P < 0.05) egg albumen height and Haugh unit at wk 8 or 12, and the responses were linear and quadratic (P < 0.05). The body weight of breeders, absolute and relative weight of oviduct, number and total weight of preovulatory follicles (POF), and its proportion relative to ovarian weight were increased (P < 0.05), and the responses were linear (P < 0.01) and quadratic (P < 0.001). Ovarian weight increased quadratically (P < 0.05), and the mean weight of POF increased (P < 0.05), linearly and quadratically. The proportion of small yellow follicles relative to ovary weight decreased (P < 0.01) linearly and quadratically. At wk 16 of the trial period, the serum albumin content and alanine aminotransferase activity decreased (P < 0.05) and the creatinine content increased (P < 0.01) linearly and quadratically. The Trp requirements were estimated to be 3.14 g/kg for optimizing egg production, 2.93 g/kg for egg mass, and 2.92 g/kg for FCR. Overall, dietary Trp levels (1 to 6 g/kg) affected productive performance, egg quality, reproductive organ and ovarian follicle development, and serum biochemical indices of layer duck breeders, and a diet containing 2.9 to 3.1 g Trp per kg feed was adequate during the laying period (22 to 37 wk of age).

The application of reduced dietary crude protein levels supplemented with additional amino acids in laying ducks

This study was aimed at studying use of reduced dietary crude protein (CP) level supplemented with additional amino acids in laying ducks. A total of 720 Jingjiang ducks (50 wk) were randomly assigned to 5 treatments and fed 5 basal diets with CP levels at 17.5, 16.5, 15.5, 14.5, or 13.5%, with additional amino acids added to each diet for 12 wk. Each treatment had 6 replicates of 24 ducks each. Dietary CP levels affected (P < 0.05) egg production and mass of laying ducks, and there was a linear and quadratic decrease with decreasing CP levels (P < 0.05). Dietary CP levels did not affect egg weight and feed conversion ratio (FCR), but egg weight decreased linearly (P < 0.05); FCR increased linearly and quadratically (P < 0.05) with decreasing CP levels. There were no significant differences in egg quality among the different CP levels (P > 0.05). Ovarian weight, total and mean weight of preovulatory follicles, and total weight of small yellow follicles (SYF) were decreased by dietary CP levels (linear, P < 0.01 and quadratic, P < 0.05). The oviductal weight decreased linearly (P < 0.05), and the number of SYF decreased linearly and quadratically with decreasing CP levels (P < 0.05). The serum estradiol content decreased linearly with dietary CP levels (P < 0.05). The serum contents of luteinizing hormone, prolactin, and progesterone decreased (P < 0.05), linearly and quadratically (both P < 0.01) with decreasing CP levels. The serum contents of creatinine (CRE), triglycerides (TG), total cholesterol (TC), and alanine aminotransferase (ALT) activity were affected (P < 0.05) by different dietary CP levels. The total protein content increased linearly (P < 0.05), TC content increased quadratically (P < 0.05), and contents of albumin, CRE, TG, and phosphorus, and activities of aspartate aminotransferase and ALT increased linearly and quadratically (both P < 0.05) with decreasing CP levels. Overall, reduced dietary CP levels with addition of amino acids affected the laying performance, the development of reproductive organs and ovarian follicles, serum hormones, and biochemical indices of laying ducks. Dietary CP levels can be reduced to 14.5% with additional amino acid supplementation for 12 wk in laying ducks without negative effect on laying performance and egg quality.

Effects of capsaicin on laying performance, follicle development, and ovarian antioxidant capacity in aged laying ducks

The present study was conducted to evaluate the effects of dietary addition of capsaicin (CAP) on egg production performance, follicular development, and ovarian antioxidant capacity in laying ducks. Three hundred seventy eight 58-wk-old laying ducks were randomly divided into 3 treatments, each treatment consisted 6 replicates, with 12 individually caged laying ducks per replicate. Ducks fed a basal diet served as control, the other 2 groups of ducks were fed the same diet containing 150 mg/kg CAP but in the manner of feed restriction (pair-fed) or ad libitum fed. The experiment lasted for 8 wk. The results showed that the dietary supplementation with CAP under conditions of ad libitum feeding increased feed intake (P < 0.001) and tended (P < 0.1) to increase egg production and egg weight in laying ducks but had no effects on daily egg mass and feed conversion ratio. The relative weight of large yellow follicles from the 2 CAP-supplemented groups at 64 wk of age were significantly higher than that of the controls (P = 0.01). The relative weight of the small yellow follicles in the CAP free-fed group was significantly higher than that of the other 2 groups (P < 0.01). Capsaicin supplementation under ad libitum feding conditions tended to increase the number of dominant follicles in laying ducks (P = 0.06). The ovarian mRNA expression of genes related to calcium signaling (TRPV4, ATP2A2, ITPR1, and CaM) in the CAP ad libitum fed groups were significantly higher than those of the other 2 groups (P < 0.05). The ovarian mRNA expression of CDK1 in CAP free-fed ducks was significantly higher than that of the other 2 groups (P = 0.01). Capsaicin supplementation significantly increased the plasma glutathione peroxidase activity (P < 0.01) in comparison with the control group but reduced the malondialdehyde content in the ovaries of laying ducks (P < 0.01). The results of this study indicates that dietary supplementation of CAP increased feed intake and improved egg production performance probably by activating calcium signaling pathway and improving redox status.

Estimation of dietary manganese requirement for laying duck breeders: effects on productive and reproductive performance, egg quality, tibial characteristics, and serum biochemical and antioxidant indices

This study was aimed at estimating the dietary manganese (Mn) requirement for laying duck breeders. A total of 504 Longyan duck breeders (body weight: 1.20 ± 0.02 kg) aged 17 wk were randomly allocated to 6 treatments. The birds were fed with a basal diet (Mn, 17.5 mg/kg) or diets supplemented with 20, 40, 80, 120, or 160 mg/kg of Mn (as MnSO₄·H₂O) for 18 wk. Each treatment had 6 replicates of 14 ducks each. As a result of this study, dietary Mn supplementation did not affect the productive performance of laying duck breeders in the early laying period (17–18 wk), but affected egg production, egg mass, and feed conversion ratio (FCR) from 19 to 34 wk (P < 0.05), and there was a linear and quadratic effect of supplement level (P < 0.05). The proportion of preovulatory ovarian follicles increased (P < 0.01) linearly and quadratically, and atretic follicles (weight and percentage) decreased (P < 0.05) quadratically with dietary Mn supplementation. The density and breaking strength of tibias increased (quadratic; P < 0.05), the calcium content of tibias decreased (linear, quadratic; P < 0.01), and Mn content increased (linear, quadratic; P < 0.001) with increase in Mn. The addition of Mn had a quadratic effect on serum contents of estradiol, prolactin, progesterone, luteinizing hormone, and follicle-stimulating hormone (P < 0.001). Dietary Mn supplementation decreased serum contents of total protein (linear, P < 0.05), glucose (quadratic, P < 0.05), total bilirubin, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and calcium (linear, quadratic; P < 0.05). The serum total antioxidant capacity and total and Mn-containing superoxide dismutase activities increased (linear, quadratic; P < 0.001), and malondialdehyde content decreased (linear, quadratic; P < 0.001) in response to Mn supplemental levels. The dietary Mn requirements, in milligram per kilogram for a basal diet containing 17.5 mg/kg of Mn, for Longyan duck breeders from 19 to 34 wk of age were estimated to be 84.2 for optimizing egg production, 85.8 for egg mass, and 95.0 for FCR. Overall, dietary Mn supplementation, up to 160 mg/kg of feed, affected productive performance, tibial characteristics, and serum biochemical and antioxidant status of layer duck breeders. Supplementing this basal diet (17.5 mg/kg of Mn) with 85 to 95 mg/kg of additional Mn was adequate for laying duck breeders during the laying period.

The effects of dietary Se on productive and reproductive performance, tibial quality, and antioxidant capacity in laying duck breeders

This study evaluated the optimal concentrations of dietary Se for the productive and reproductive performance, tibial quality, and antioxidant status in duck breeders aged 23 to 49 wk. In total, 432 Longyan duck breeders aged 22 wk were allotted randomly to 6 treatments, each with 6 replicates of 12 individually caged birds. The experiment lasted for 27 wk, and birds were fed corn-soybean meal-based diets containing 0.11, 0.19, 0.27, 0.35, 0.43, or 0.51 mg Se/kg, respectively. The tested dietary Se levels did not affect egg production and tibial quality of duck breeders. The Se contents of the shell, yolk or albumin, whole egg, and the fertility of set eggs increased in a linear and quadratic manner (P < 0.05) in response to the increased dietary Se level, whereas the yolk malondialdehyde (MDA) and embryonic mortality decreased. The activities of glutathione peroxidase 3 (Gpx3) in plasma and Gpx1 in the erythrocytes and livers of breeder ducks increased in a linear and quadratic manner (P < 0.05) in response to increased dietary Se levels, whereas the total superoxide dismutase (T-SOD) activity increased and the MDA concentration decreased in the liver. The activity of Gpx3 in the plasma and Gpx1 in the erythrocytes and livers of newly hatched ducklings increased linearly (P < 0.01) with the increase in Se level, whereas the T-SOD activity and MDA concentration did not change. In conclusion, diets containing 0.27 mg Se/kg led to the highest egg fertility and hatchability in Longyan duck breeders, and using levels >0.19 mg Se/kg diet enhanced the antioxidant capacity in breeders and their offspring. The regression model indicated that dietary Se levels 0.19, 0.27, 0.28, 0.24, and 0.30 mg/kg are optimal levels to obtain maximum Se deposition efficiency in eggs, egg fertility, Gpx1 activity in erythrocytes and liver in duck breeders, and plasma activity of Gpx3 in newly hatched ducklings, respectively.

Effects of ${\rm \small L}$-methionine on growth performance, carcass quality, feather traits, and small intestinal morphology of Pekin ducks compared with conventional ${\rm \small {DL}}$-methionine

The research studied the effects ofl-methionine (l-Met) on growth performance, carcass quality, feather traits, and small intestinal morphology of Pekin ducks compared with conventionaldl-methionine (dl-Met). A total of 1080, 1-day-old male Pekin ducks were randomly allotted to 9 groups with 6 replicate pens of 20 birds each. During the starter phase (1 to 14 d), ducks were fed a basal diet (Met, 0.30%) or that supplemented with dl-Met or l-Met at 0.05, 0.10, 0.15, or 0.20% of feed. During the grower phase (15 to 35 d), ducks were fed a basal diet (Met, 0.24%) or that supplemented with dl- Met or l-Met at 0.04, 0.08, 0.12, or 0.16% of feed. Compared with ducks fed the basal diet, supplementation with either dl- Met or l-Met increased the body weight (BW) of ducks at days 14 and 35, increased average daily gain (ADG) and average daily feed intake (ADFI), decreased F:G at the starter phase, and increased ADG over the whole 35-d period (P < 0.05). The efficacy of l-Met compared to dl- Met was 140.1% for 14-d BW, 137.6% for ADG and 121.0% for F:G for days 1 to 14. Ducks fed diets supplemented with l-Met had greater proportion of leg muscle, higher than in ducks provided with dl- Met (P < 0.05). The breast muscle proportion was enhanced with dl- Met rather than l- Met supplementation (P < 0.01). The back feathers score and fourth primary wing feather length were increased with dl- Met or l-Met supplementation (P < 0.01), and there was increased efficacy of l-Met relative to dl- Met for back feathers score (153.1%). Dietary dl- Met or l- Met supplementation increased villus height of ileal mucosa of ducks at days 14 and 35 (P < 0.01). Overall, dietary l-Met or dl- Met supplementation affected the growth performance of ducks during the starter phase, and improved the feather traits and small intestinal morphology. The efficacy of l-Met to dl- Met ranged from 120 to 140% for growth performance of young ducks (1 to 14 d) and was 153% for the feather traits of ducks (35 d).

Effects of dietary lysine on productivity, reproductive performance, protein and lipid metabolism-related gene expression in laying duck breeders

This study investigated whether dietary lysine (Lys) affects productive performance and expression of genes related to protein and lipid metabolism in laying duck breeders. Longyan duck breeders (n = 540, 19 wk of age) were randomly assigned to 6 groups with 6 replicates of 15 birds each. Breeders were fed diets with 6 total Lys levels (6.4, 7.2, 8.0, 8.8, 9.6, and 10.4 g/kg) for 26 wk duration. Egg production, egg weight, egg mass, feed conversion ratio, hatchability, hatchling weight, albumen weight, eggshell weight, yolk weight, and yolk proportion increased with dietary Lys levels (P < 0.05). Dietary Lys level had a linear (P < 0.05) and quadratic (P < 0.05) effects on maternal hepatic expression of mechanistic target of rapamycin, eukaryotic translation initiation factor 4E binding protein 1, ubiquitin conjugating enzyme E2K (UBE2K), cathepsin B (CTSB), and quadratically (P < 0.05) increased the concentrations of plasma Lys, leucine, threonine, and tryptophan in duck breeders. In contrast, maternal dietary Lys suppressed expression of proteasome 26S subunit, UBE2K, and CTSB in the liver of hatchlings. Moreover, relative expression of peroxisome proliferator-activated receptors alpha, carnitine palmitoyltransferase 1A, and very low density apolipoprotein-II increased linearly (P < 0.05) and quadratically (P < 0.05), and that of VLDL receptor (VLDLR) decreased quadratically (P < 0.05) in the liver of duck breeders with increasing dietary Lys levels; hepatic triglyceride and cholesterol contents were reduced. Maternal dietary Lys suppressed hepatic expression of VLDLR in the hatchlings. A diet containing 8.6 g Lys/kg promoted protein turnover and lipid metabolism in laying duck breeders, which positively reflected in the productivity and reproductive performance.

Estimation of dietary zinc requirement for laying duck breeders: effects on productive and reproductive performance, egg quality, tibial characteristics, plasma biochemical and antioxidant indices, and zinc deposition

This study evaluated the effects of different dietary zinc (Zn) levels on productive and reproductive performance, egg quality, tibial characteristics, plasma biochemical and antioxidant indices, and zinc deposition in laying duck breeders. A total of 504 Longyan duck breeders aged 21 wk were randomly allocated to 6 treatments and fed a basal diet (Zn, 27.7 mg/kg) or that basal diet supplemented with Zn (as ZnSO₄·H₂ O) at 10, 20, 40, 80, or 160 mg Zn per kg of feed for 20 wk. Each group had 6 replicates of 14 ducks each. Dietary Zn supplementation affected (P < 0.05) the egg production, FCR, and shell thickness of laying duck breeders from 21 to 40 wk, and there was a quadratic (P < 0.05) effect between them. Dietary Zn supplementation affected (P < 0.05) and quadratically (P < 0.001) increased the breaking strength, density, and dry defatted weight of tibias. Alkaline phosphatase, calcium, phosphorus, total superoxide dismutase, glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) activities or content in plasma were affected (P < 0.05), and quadratically (P < 0.01) changed by dietary Zn levels. Dietary Zn supplementation affected (P < 0.01) and increased the Zn deposition in egg yolk (linear, P < 0.05; quadratic, P < 0.001) and tibia (linear, P < 0.05). The dietary Zn requirements, in mg/kg for a basal diet containing 27.7 mg/kg Zn, for Longyan duck breeders from 21 to 40 wk of age were estimated to be 65.4 for optimizing egg production, 68.6 for FCR, 102 for hatchling BW, 94.7 for eggshell thickness, 77.2 for tibial breaking strength, 81.4 for tibial density, 78.9 for tibial dry defatted weight, 69.5 for plasma GSH-Px activity, 72.4 for plasma MDA content, and 94.6 for Zn content in tibia. Overall, dietary Zn supplementation, up to 160 mg/kg feed, affected the productive performance, eggshell thickness, tibial characteristics, plasma antioxidant status, and Zn deposition of layer duck breeders. Supplementing this basal diet (27.7 mg/kg Zn) with 70 to 80 mg/kg additional Zn was adequate for laying duck breeders during the laying period.

Dietary curcumin enhances intestinal antioxidant capacity in ducklings via altering gene expression of antioxidant and key detoxification enzymes

The study investigated the effects of dietary curcumin supplementation on tissue distribution of curcumin and its metabolites, intestinal antioxidant capacity, and expression of detoxification-related genes in ducks. A total of 720 one-day-old male Cherry Valley Pekin ducklings (initial BW 58.6 ± 0.1 g) were randomly assigned to 4 dietary groups each with 6 replicates of 30 ducks using a single factorial arrangement design. Ducks in the control group were fed a basal diet and the remainder were fed the basal diet supplemented with 200, 400, or 800 mg/kg curcumin. The experiment lasted for 21 D. Curcumin was present at 13.12 to 16.18 mg/g in the cecal digesta, 75.50 to 575.40 μg/g in jejunal mucosa, 35.10 to 73.65 μg/g in liver, and 7.02 to 7.88 μg/mL in plasma. The jejunal and hepatic contents of curcumin increased significantly (P < 0.05) in response to supplementation with 400 and 800 mg/kg of curcumin respectively, compared with 200 mg curcumin/kg group. There was a linear (P < 0.001) effect of dietary curcumin on relative abundance of SOD1, GPX1, CAT, HO-1, and Nrf2 transcripts, and a quadratic (P < 0.001) increase in the activities of GSH-Px and T-AOC in jejunal mucosa. The expression of CYP1A4, CYP2D17 increased and CYP1B1, CYP2A6 decreased linearly (P < 0.001) with dietary curcumin concentrations. In addition, dietary curcumin increased gene expression of GST, MRP6, and ABCB1 in jejunal mucosa. In conclusion, dietary supplementation with 200 to 800 mg/kg curcumin enhanced the accumulation of curcumin and its metabolites in jejunum as well as increasing the antioxidant capacity and detoxification potential, which play major roles in the protection of duck intestines against damage.

Effects of corn dried distillers' grains with solubles on performance, egg quality, yolk fatty acid composition and oxidative status in laying ducks

The study investigated the effects of increasing content of corn distillers' dried grains with solubles (DDGS) in the diets of laying ducks on oxidative status, laying performance, egg quality, and egg yolk fatty acid composition. Longyan females (1080) with similar BW at 17 wk of age were randomly assigned to 6 treatment groups, each consisting of 6 replicates of 30 birds. The basal diet (I) was a typical corn-soybean ration while the experimental diets (II to VI) substituted corn DDGS for soybean meal and wheat bran and a small reduction of corn. The level of substitution in diets (II to VI) was 6%, 12%, 18%, 24% and 30%. The experiment lasted for 18 wk. Average egg weight decreased linearly as the level of corn DDGS inclusion increased (P < 0.001). Haugh unit, albumen weight, and proportion declined as linear responses to corn DDGS substitution (P < 0.05), but yolk color linearly increased (P < 0.001); the proportions of oleic (C18:1) and total monounsaturated fatty acids in egg yolk linearly decreased with increasing corn DDGS and many of the key polyunsaturated fatty acids (PUFAs) like linoleic (C18:2n-6), arachidonic (C20:4n-6) and α-linolenic (C18:3n-3) acids linearly increased (P < 0.001), but not those of eicosapentaenoic (C20:5n-3) and docoshexaenoic (C22:6n-3) acids. The PUFAs n-6/n-3 ratio linearly increased with increasing corn DDGS level (P < 0.001). Increasing corn DDGS linearly increased hepatic expression of GPX1, HO-1, and Nrf2 and hepatic activity of GSH-Px and the liver content of MDA (P < 0.001). There were no treatment effects on egg production, egg mass, feed conversion ratio, eggshell thickness, strength, and yolk cholesterol content (P > 0.05). In conclusion, the current study indicates that the use of corn DDGS is possible as a replacement, primarily for soybean meal at levels up to 18% in the diets of laying ducks without affecting laying performance, egg quality, and antioxidant status. Increasing amounts of corn DDGS linearly increased egg yolk concentrations of key fatty acids like like C18:2n-6 and C18:3n-3 and the antioxidant enzyme activity of GSH-Px through the Nrf2 pathway to avoid oxidative stress.

Optimization of dietary zinc for egg production and antioxidant capacity in Chinese egg-laying ducks fed a diet based on corn-wheat bran and soybean meal

The aim of this study was to evaluate the effect of zinc supplementation on productive performance and antioxidant status in laying ducks. Five-hundred-four laying ducks were divided into 7 treatments, each containing 6 replicates of 12 ducks. The ducks were caged individually and fed a corn-soybean meal and wheat bran basal diet (37 mg Zn/kg) or the basal diet supplemented with 15, 30, 45, 60, 75, or 90 mg Zn/kg (as zinc sulfate). During the early laying period of 10 d (daily egg production <80%), egg production, daily egg mass, and FCR increased quadratically with increasing dietary Zn levels (P < 0.05). The highest egg production and daily egg weight were obtained when 30 or 45 mg Zn/kg diet was supplemented, with lowest FCR. Similarly, the highest egg production and daily egg mass were observed in the group supplemented with 30 or 45 mg Zn/kg during the peak laying period of the subsequent 120 d (daily egg production >80%). Average egg weight and feed intake did not differ among the groups of graded Zn supplementation.The egg quality was not affected by dietary Zn, including the egg shape index, Haugh unit, yolk color score, egg composition, and shell thickness. The activities of plasma activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) increased in a quadratic manner (P < 0.001) with increasing supplemental Zn. Plasma concentration of Zn increased quadratically (P < 0.05) as dietary Zn increased. The hepatic activity of Cu/Zn-SOD and GSH-PX increased quadratically (P < 0.05) with increasing dietary Zn. Plasma Zn concentrations were positively correlated with activities of T-SOD (P < 0.05), and positively with plasma Cu. Plasma concentration of reduced glutathione was correlated with plasma Cu. In conclusion, supplementation of Zn at 30 or 45 mg/kg to a corn-wheat bran and soybean basal diet may improve the productive performance and enhance the antioxidant capacity.

Effects of oxidative stress induced by high dosage of dietary iron ingested on intestinal damage and caecal microbiota in Chinese Yellow broilers

The objective of this trial was to test the effects of oxidative stress induced by a high dosage of dietary iron on intestinal lesion and the microbiological compositions in caecum in Chinese Yellow broilers. A total of 450 1-day-old male chicks were randomly allotted into three groups. Supplemental iron (0, 700 and 1,400 mg/kg) was added to the basal diet resulting in three treatments containing 245, 908 and 1,651 mg/kg Fe (measured value) in diet respectively. Each treatment consisted of six replicate pens with 25 birds per pen. Jejunal enterocyte ultrastructure was observed by transmission electron microscopy. The results showed that a high dosage of dietary iron induced oxidative stress in broilers. Dilated endoplasmic reticulum (ER), autophagosome formation of jejunal enterocytes and decreased villi were caused by this oxidative stress. Compared to the control, concentration of the malondialdehyde (MDA) in jejunal mucosa in the 908 and 1,651 mg/kg Fe groups increased by 180% (p < .01) and 155% respectively (p < .01); activity of copper-zinc superoxide dismutase (Cu/ZnSOD) increased in jejunum (p < .01); and the concentration of plasma reduced glutathione (GSH) decreased by 34.9% (p < .01) in birds fed 1,651 mg/kg Fe. Gene expression of nuclear factor, erythroid-derived 2-like 2 (Nrf2) and zonula occludens-1 (ZO-1), in the higher dietary Fe groups was enhanced (p < .05). Species of microbial flora in caecum increased caused by oxidative stress. The PCR-DGGE (denaturing gradient gel electrophoresis) dendrograms revealed different microbiota (65% similarity coefficient) between the control and iron-supplemented groups (p < .05). These data suggest high dosage of iron supplement in feed diet can induce oxidative stress in Chinese Yellow broilers, and composition of microbiota in the caecum changed. It implied there should be no addition of excess iron when formulating diets in Chinese Yellow broilers.

Effects of high ambient temperature on meat quality, serum hormone concentrations, and gene expression in the longissimus dorsi muscle of finishing pigs

This study examined the effect of high ambient temperature on the growth performance, meat quality, activity of the hypothalamo-pituitary-adrenal axis, and related gene expression in finishing pigs. All pigs received the same corn-soybean meal-based diet. Twenty-four Landrace pigs (initial bodyweight of 77.64 ± 0.67 kg) were assigned into three groups: Group 1 (22°C, ad libitum, 81% humidity); Group 2 (22°C, pair-fed to Group 3, 78% humidity); Group 3 (35°C, ad libitum, 78% humidity). The experiment lasted for 30 days. The average daily feed intake and average daily gain were markedly reduced in Group 3 compared with Group 1 (P < 0.05). The intramuscular fat content of longissimus dorsi muscle was decreased in Groups 2 and 3 (P < 0.05) when compared with Group 1. Muscle pH at 24 h post-mortem was higher in Group 3 (P < 0.05) compared with Groups 1 and 2, and the pH at 48 h post-mortem was higher in Group 3 (P < 0.05) than in Group 1. The MyHC IIb transcript abundance was lower in Group 3 (P < 0.05) than in the other two groups and that of MyHC IIx was higher in Group 3 than in Group 2 (P < 0.05). The relative abundance of calpastatin transcripts was lower in Group 3 (P < 0.05) than in the other two groups. Cortisol concentrations were lower in Group 3 (P < 0.05) than in Groups 1 and 2 on Day 3. Corticotropin releasing hormone concentrations in Group 3 were lower at Day 3 (P < 0.05) when compared with Group 2 and at Day 30 when compared with Groups 1 and 2. Glucagon concentrations were lower in Group 3 (P < 0.05) when compared with Groups 1 and 2 on Day 30. These results indicate that the decreased intramuscular fat content of pigs at high ambient temperature results from the reduction in feed intake. Independently of its effect on feed intake, high ambient temperature affected the meat quality of finishing pigs by increasing pH value probably due to the lower serum concentrations of corticotropin releasing hormone, and inducing a transition of muscle fibre types from IIb to IIx.

Estimation of L-threonine requirements for Longyan laying ducks

Objective

A study was conducted to test six threonine (Thr) levels (0.39%, 0.44%, 0.49%, 0.54%, 0.59%, and 0.64%) to estimate the optimal dietary Thr requirements for Longyan laying ducks from 17 to 45 wk of age.

Methods

Nine hundred Longyan ducks aged 17 wk were assigned randomly to the six dietary treatments, where each treatment comprised six replicate pens with 25 ducks per pen.

Results

Increasing the Thr level enhanced egg production, egg weight, egg mass, and the feed conversion ratio (FCR) (linearly or quadratically; p<0.05). The Haugh unit score, yolk color, albumen height, and the weight, percentage, thickness, and breaking strength of the eggshell did not response to increases in the Thr levels, but the albumen weight and its proportion increased significantly (p<0.05), whereas the yolk weight and its proportion decreased significantly as the Thr levels increased.

Conclusion

According to a regression model, the optimal Thr requirement for egg production, egg mass, and FCR in Longyan ducks is 0.57%, while 0.58% is the optimal level for egg weight from 17 to 45 wk of age.

Effects of high peanut meal with different crude protein level supplemented with amino acids on performance, carcass traits and nitrogen retention of Chinese Yellow broilers

This study assessed the effects of feeding high peanut meal diets of reduced crude protein (CP) content supplemented with essential amino acids (EAA) on growth performance, carcass traits, biochemical indices in plasma, and nitrogen (N) retention of male and female Lingnan Yellow broilers from day 22 to day 42 of age. Each of four dietary treatments (19%, 18%, 17% or 16% CP, dietary CP level reduced by the reduced dietary peanut meal) contained six replicate pens with 35 birds of each sex (males and females with equal number), separately (1680 in total). The three diets with reduced CP were supplemented with 5 EAA to meet the requirements and provide the same levels as in the 19% CP diet. Average daily gain decreased and feed:gain ratio was worse in both sexes with reduced CP% (linear, p < 0.05). Dressing percentage increased as CP% decreased in males (linear, p < 0.05) and thigh muscle percentage reduced slightly in females (linear, p < 0.05). Abdominal fat percentage of males fed the 17% CP was the lowest (quadratic, p < 0.05). The plasma metabolic indices, concentrations of triglycerides and malondialdehyde, showed linear responses to reduced CP% (p < 0.05) with triglycerides increasing while malondialdehyde decreased. Plasma uric acid increased in females (linear, p < 0.05), but not in males, as CP% decreased. Efficiency of N retention increased and N excretion strikingly decreased with lower CP diets (p < 0.001), and both variables showed significant (p < 0.05) linear and quadratic effects. It is concluded that there was a limit to which dietary CP of broilers could be reduced without adverse effects. Dietary CP could be reduced to 17% for males and 18% for females (or 18% when fed together) between day 22 and day 42, if diets are supplemented with synthetic EAA.

Effect of Lactobacillus plantarum on diarrhea and intestinal barrier function of young piglets challenged with enterotoxigenic Escherichia coli K88

The present study was performed to investigate the preventative effect of Lactobacillus plantarum on diarrhea in relation to intestinal barrier function in young piglets challenged with enterotoxigenic Escherichia coli (ETEC) K88. Seventy-two male piglets (4 d old) were assigned to 2 diets (antibiotic-free basal diet with or without L. plantarum, 5 × 10(10) cfu/kg diet) and subsequently challenged or not with ETEC K88 (1 × 10(8) cfu per pig) on d 15 in a 2 × 2 factorial arrangement of treatments. Feed intake and BW were measured on d 15 and 18 (3 d after challenge) for determination of growth performance. On d 18, 1 piglet from each pen was slaughtered to evaluate small intestinal morphology and expression of tight junction proteins at the mRNA and protein levels while another piglet was used for the intestinal permeability test. Before and after ETEC K88 challenge, piglets fed L. plantarum had greater BW, ADG, and ADFI (P < 0.05) and marginally greater G:F (P < 0.10) compared to piglets fed the unsupplemented diet. After ETEC K88 challenge, the challenged piglets did not show an impaired growth performance but had greater incidence of diarrhea compared to the nonchallenged piglets. There was an interaction between dietary L. plantarum and ETEC K88 challenge (P < 0.05) as L. plantarum prevented the ETEC K88-induced diarrhea. Piglets challenged with ETEC K88 also had greater urinary lactulose:mannitol and plasma concentration of endotoxin, shorter villi, deeper crypt depth, and reduced villous height:crypt depth in the duodenum and jejunum and decreased zonula occludens-1 mRNA and occludin mRNA and protein expression in the jejunum (P < 0.05). These deleterious effects caused by ETEC K88 were inhibited by feeding L. plantarum (P < 0.05). There were no effects of either treatment on the morphology and expression of tight junction proteins in ileum. In conclusion, L. plantarum, given to piglets in early life, improved performance and effectively prevented the diarrhea in young piglets induced by ETEC K88 challenge by improving function of the intestinal barrier by protecting intestinal morphology and intestinal permeability and the expression of genes for tight junction proteins (zonula occludens-1 and occludin).

Dietary supplementation with carnosine improves antioxidant capacity and meat quality of finishing pigs

This study was conducted to determine the effect of dietary carnosine (β-alanyl-L-histidine) supplementation on antioxidant capacity and meat quality of pigs. 72 pigs approximately 60 kg were fed a corn- and soybean meal-based diet supplemented with 0, 25, 50 or 100 mg carnosine per kg diet for 8 weeks. Carnosine supplementation did not affect growth performance and carcass traits of pigs. However, the addition of 100 mg carnosine per kg diet increased pH value of muscle at 45 min, 24 h and 48 h postmortem. It also decreased drip loss at 48 h postmortem and increased redness value of muscle at 45 min postmortem (p < 0.05). The addition of 100 mg carnosine per kg diet enhanced glycogen concentration and Ca-ATPase activity at 24 and 48 h postmortem, and reduced malondialdehyde and carbonyl protein complexes concentrations in muscle at 24 h postmortem (p < 0.05). The addition of 100 mg carnosine per kg diet increased glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and catalase (CAT) activities in plasma, liver or muscle, as well as SOD and GSH-Px genes expression in muscle (p < 0.05). Taken together, these findings indicate that carnosine supplementation improves antioxidant capacity and meat quality of pigs.

Effects of spray-dried animal plasma on serous and intestinal redox status and cytokines of neonatal piglets

The study investigated the effects of dietary supplementation with spray-dried animal plasma (SDAP) on growth performance, intestinal morphology, as well as serum and intestinal cytokines and antioxidant indicators of artificially reared neonatal piglets. Three diets, 1) control (a fish meal basal diet), 2) SDAP (containing 10% SDAP), and 3) autoclaved SDAP (auSDAP; containing 10% auSDAP), were fed to 36 weaned piglets (3 d old), which were randomly allotted to 3 groups. At 21 d of age, blood and intestinal mucosal samples were collected from all piglets after they were slaughtered. Compared with the control, both SDAP and auSDAP improved ADFI and duodenal villus height of piglets (P < 0.05), whereas SDAP increased ADG and duodenal villus height to crypt depth ratio (P < 0.05). Piglets fed SDAP and auSDAP had reduced malondialdehyde (MDA) content in mucosa (P < 0.05). The concentration of serum MDA was decreased and mucosal catalase (CAT) activities were increased in piglets fed SDAP diet than those fed the control diet (P < 0.05). In the mucosa, both SDAP and auSDAP decreased tumor necrosis factor α, IL-6, transforming growth factor β, and soluble IL-2 receptor contents (P < 0.05). Mucosal IL-1β was decreased in SDAP compared with auSDAP and control groups (P < 0.05). The SDAP and control groups had increased mucosal IL-2 compared with auSDAP group (P < 0.05). The cytokines in serum were not affected by SDAP and auSDAP. The results indicate that both SDAP and auSDAP improved the growth performance of neonatal piglets, whereas the SDAP had a greater effect. The benefits of SDAP probably resulted from the promotion of the intestinal development, which were accompanied by the increased antioxidant capacity and the decreased production of inflammatory factors in the intestinal mucosa.