Effects of different dietary vitamin D combinations during the grower phase and the feed restriction phase on growth performance and sternal morphology, mineralization, and related genes expression of bone metabolism in Pekin ducks.

Our study aimed to investigate the effects of different dietary vitamin D (VD) combinations during the grower (1-32 d of age) and feed restriction (33-52 d of age) phases on growth performance. We also evaluated sternal morphology, mineralization, and related genes expression of bone metabolism as well as absorption of calcium and phosphorous in duodenal mucosa and kidney in Pekin ducks. During the grower phase, we used 2 VD regimes (Group A: 3,160 IU/kg VD3; Group B: 400 IU/kg VD3 + 69 µg/kg 25-OH-D3). Each dietary treatment had 50 replicate pens of 10 ducks per pen. During the feed restriction phase, 30 replicate pens selected from Group A and Group B, repetitively, were redivided into 5 different dietary VD regimes to form a 2 × 5 experimental design. Each group consisted of 6 replicates, each with 10 ducks. During the feed restriction phase, we evaluated 5 different dietary VD combinations were as follows: T1: 2,000 IU/kg VD3 ; T2: 5,000 IU/kg VD3; T3: 3,620 IU/kg VD3 + 34.5 µg/kg 25-OH-D3; T4: 2,240 IU/kg VD3 + 69 µg/kg 25-OH-D3; T5: 1,800 IU/kg VD3 + 80 µg/kg 25-OH-D3). Results showed that Group B combinations with T5 had a better growth performance and breast meat deposition (P < 0.1). Regardless of 5 dietary VD regimes during the feed restriction phase, Group B significantly increased (P < 0.05) 52 d sternal depth and tended to increase (P < 0.1) 52 d sternal defatted weight, ash content, and phosphate (P) content of ducks. A significant interactive effect (P < 0.05) was observed on the mRNA abundance of DMP1 and Sost1 as well as RANKL/OPG in sternum and of VDR in duodenal mucosa of ducks at 52 d of age between dietary VD combinations during 2 phases. These results indicated that dietary VD regimes during the grower phase could affect the effectiveness of dietary VD regimes during the feed restriction phases; Dietary VD combinations of both phases could affect the genes expression of bone formation and the absorption as well as reabsorption of calcium and phosphorus in duodenum and kidney.

Effects of supplemented mode of emulsifier on growth performance, serum biochemical index, quality of meat and skin fat, and nutrient utilization in Pekin ducks.

In our previous experiment, we found that fats with pre-emulsification (PreE), a new supplemented mode of emulsifier, had an improved bioavailability for Pekin ducks than fats without PreE based on dietary EE utilization. Therefore, this study was conducted to investigate the effects of the supplemented mode of emulsifier (PreE vs. emulsifier direct supplementation) on the growth performance, serum biochemical index, quality of meat and skin fat, and nutrient utilization in Pekin ducks. A total of 640 healthy 10-day-old Pekin male ducks (408.65 ± 12.00 g) were randomly allocated into 4 treatments with 16 replicates of 10 birds each. The 4 dietary treatments were as follows: the positive control group (PC; the oil supplemented amount of 6%), the negative control group (NC; the oil supplemented amount of 5.4%), the emulsifier group (E; NC diet with an emulsifier added directly), and the oil pre-emulsification group (PreE; NC diet with oil PreE). The results showed reducing the amount of fat in the diet (NC vs. PC) significantly decreased growth performance and quality of skin fat, and affected serum lipid metabolism (P < 0.05). Interestingly, the body weight (BW), body weight gain (BWG), and the shear force of skin fat were increased, but the feed to gain ratio (F/G) was markedly decreased in the PreE group (P < 0.05) compared to those in the NC group, and these levels were similar to those in the PC group (P > 0.05). Additionally, the utilization of dietary dry matter (DM), ether extract (EE), and total phosphorous (TP) were increased, but the activity of aspartate aminotransferase (AST) in serum was decreased in the PreE group compared to those in the NC group (P < 0.05). Furthermore, compared to the E group, the F/G was decreased (P < 0.05), and the utilization of dietary EE, the shear force of skin fat and content of collagen in skin fat were markedly increased (P < 0.05) in the PreE group. However, no differences were observed (P > 0.05) in growth performance between the group administered a direct supplementation of emulsifier and the control groups (PC and NC). These results indicate that the negative effect of reducing the oil supplementation amount (-0.6%) in the diet can be restored by supplementation with emulsifier, especially by oil with PreE.

Effects of a high-fat diet on the growth performance, lipid metabolism, and the fatty acids composition of liver and skin fat in Pekin ducks aged from 10 to 40 days.

This study aimed to investigate the effect of a high-fat diet on the growth performance, serum, liver, and skin lipid metabolism as well as the fatty acids composition of liver and skin fat in Pekin ducks from 10 to 40 d of age based on a pair-fed group. Two hundred forty healthy male ducks (10 d old, 470.53 ± 0.57 g) were randomly divided into 3 groups (8 replicates per cage of 10 ducks): a normal diet (ND, 3% fat), a high-fat diet (HFD, 9% fat), and a pair-fed diet (PFD, given the ND in an amount equal to that consumed of the HFD to eliminate the effects of feed intake). The results were as follows: compared to ND feeding, HFD feeding significantly decreased (P < 0.05) the feed intake and feed:gain ratio (F:G), along with serum triglyceride and nonesterified fatty acid contents. When compared with the ND and PFD, the HFD significantly decreased (P < 0.05) the liver weight and inhibited hepatic de novo lipogenesis (glucose-6-phosphate dehydrogenase and malate dehydrogenase activities), ß-oxidation (carnitine palmitoyltransferase-1 content), and decreased saturated fatty acids and monounsaturated fatty acids deposition. Moreover, the HFD significantly increased (P < 0.05) the total fat content, lipid droplet area, and polyunsaturated fatty acids (PUFAs) content in the liver, as well as the abdominal fat weight, subcutaneous fat weight, the total fat and PUFAs content in skin fat. These results suggested that the HFD improved feed efficiency, which was related to HFD feeding inhibiting hepatic de novo lipogenesis and ß-oxidation and promoting the deposition of fat in skin as well as altering the fatty acids composition of the liver and skin fat in Pekin ducks.

Corn distiller's dried grains with solubles as an alternative ingredient to corn and soybean meal in Pekin duck diets based on its predicted AME and the evaluated standardized ileal digestibility of amino acids.

The study aimed to investigate the effects of dietary distillers dried grains with solubles (DDGS) levels on growth performance, carcass characteristic, serum biochemical indexes, meat physical and chemical quality, nutrient utilization, and standardized ileal digestibility of amino acids (SIDAA) in Pekin ducks aged 11 to 42 d based on the evaluation of its SIDAA. A total of 560 eleven-day-old Cherry Valley ducks were randomly allotted to 5 treatments with 7 replicate pens per treatment and 16 ducks per pen based on the average body weight. Six isonitrogenous and isocaloric experimental diets were formulated on a digestible amino acid basis to produce diets containing 0, 5, 10, 15, and 20% DDGS, respectively. With increasing of dietary DDGS levels, a linear and quadratic reduction (P < 0.05) was observed in the body weight (BW) at d 42, average day gain (ADG) and average day feed intake (ADFI) from d 11 to 42, breast meat yield, the moisture and protein content in the breast meat, and dietary DM and EE utilization. Moreover, a linear and quadratic increase (P < 0.05) was observed in the b* value of the breast meat and serum total cholesterol and triglyceride concentrations. Compared with the control group, the group with 10% inclusion of DDGS exhibited no adverse effect on growth performance, carcass characteristics, serum biochemical indexes, meat physical and chemical quality, nutrient utilization, and the SIDAA of the diets (P > 0.05). These results suggested that 10% of corn DDGS can function as an alternative ingredient to corn and soybean meal, and the optimal levels of DDGS in the diets of ducks aged from 11 to 42 d depends more on its quality.

Evaluation of the ileal digestibility and excreta retention of phosphorus for feed phosphates in broiler chickens and in Pekin ducks.

The study aimed to determine the ileal phosphorus (P) digestibility (iPD) and the excreta P retention (ePR) of 5 monodicalcium phosphate (MCP) samples and 3 dicalcium phosphate (DCP) samples in broiler chickens and in Pekin ducks using the substitution method. A total of 720, 21-d-old Arbor Acres broiler chickens in experiment 1 and 720, 15-d-old Pekin ducks in experiment 2 were randomly allocated to 9 dietary treatments with 8 replicate cages (10 birds/cage) based on the similar mean body weight, respectively. The collection of excreta (for 72 h after a 3-d acclimation) and ileal digesta (after 6 d of feeding experimental diets) was done. The results showed the average iPD/ePR of MCP and DCP for broilers were 83.11%/74.52% and 75.34%/69.46% and for ducks were 79.37%/80.02% and 75.74%/76.44%, respectively. The iPD/ePR of MCP in broilers and the ePR of MCP in ducks were markedly higher (P < 0.05) than those of DCP. Our data suggest that using the substitution method to evaluate the bioavailability of feed phosphates has its own advantages; MCP has higher biological availability than DCP for broilers and ducks.

Effects of dietary corn germ meal levels on growth performance, serum biochemical parameters, meat quality, and standardized ileal digestibility of amino acids in Pekin ducks.

The study aimed to investigate the effects of dietary corn germ meal (CGM) levels on growth performance, carcass characteristic, serum biochemical indexes, meat physical and chemical quality, and standardized ileal digestibility of amino acids (SIDAA) in Pekin ducks from 10 to 42 d of age. A total of 420 ten-day-old Cherry Valley ducks were randomly allotted to 5 treatments with 6 replicate cages per treatment and 14 ducks per cages based on mean body weight. Five isonitrogenous and isocaloric experimental diets were formulated on a digestible amino acid basis to produce diets containing 0, 3, 6, 9, or 12% CGM. Results showed: 1) Compared with other groups, ducks fed 12% CGM significantly increased (P < 0.05) the feed to gain ratio. 2) Dietary CGM levels had no effect (P > 0.05) on the carcass traits and breast meat physical quality; but the content of crude protein presented a linear decrease (P < 0.05) in breast meat with increasing dietary CGM levels. 3) Serum biochemical indices (e.g., alanine aminotransferase, aspartate aminotransferase, glucose, high density lipoprotein cholesterol, total cholesterol, triglyceride, total protein, and urea) showed no significant differences among all groups (P > 0.05). 4) The levels of CGM had no significant effect on SIDAA of diets (P > 0.05), except for cysteine which showed a quadratic increase (P < 0.05). These results suggested that the optimal levels of CGM in diets for meat duck aged from 10 to 42 d should be below 9% based on feed to gain ratio and the content of crude protein in breast meat.

Effects of rapeseed meal on laying performance and egg quality in laying ducks.

This study was conducted to investigate the effect of different varieties of rapeseed meal (RSM) with different concentrations of glucosinolates (Gls) and erucic acid (EA) on performance and egg quality of laying ducks. A total of 576 twenty eight-wk-old laying ducks were randomly allocated to 4 treatments. Each treatment had 8 replicates of 18 laying ducks raised in 6 adjacent cages with 3 laying ducks per cage. The control diet was corn soybean meal based without RSM. Three varieties of RSM varying in Gls concentrations were supplemented to the base diet at 10% by substituting soybean meal to formulate the three RSM diets. The experiment lasted 12 wk. Diets with 10% RSM decreased average egg weight (P < 0.01) and feed intake (P = 0.07) compared with the control diet, but there was no significant difference in laying performance among the 3 RSM diets. RSM increased color value (P < 0.05) and crude protein (CP) content (P < 0.05) of yolk compared with the control diet, but had no significant effects on the other egg quality indexes including eggshell strength, albumen height, Haugh unit, and the composition ratio of eggshell, albumen and yolk. RSM decreased total monounsaturated fatty acids (MUFA) (P < 0.01) and increased total polyunsaturated fatty acids (PUFA) (P < 0.01) of yolk, but total saturated fatty acids (SFA) proportions and UFA/SFA ratio of egg yolk were not significantly affected by RSM. RSM increased deposition of trimethylamine (TMA) and 5-vinyl-1,3-oxazolidine-2-thione (5-VOT) in yolk (P < 0.01); moreover, the high Gls RSM increased deposition of TMA (P < 0.01) and 5-VOT in yolk (P < 0.01) compared with the RSM varieties low in Gls. These results suggested that dietary inclusion of 10% RSM decreased egg weight of laying ducks, and affected yolk quality especially yolk color, fatty acid profile, CP, TMA, and 5-VOT content of yolk. Moreover, RSM with higher Gls concentration resulted in higher deposition of TMA and 5-VOT in egg yolk.

Effects of enzyme-treated soy protein on performance, digestive enzyme activity and mRNA expression of nutrient transporters of laying hens fed different nutrient density diets.

It has been shown that enzyme-treated plant protein can increase performance and promote intestinal health, and save dietary protein. However, our understanding of the effects of enzyme-treated soy protein on performance and intestine function in laying hens, and its rational use, remains limited. The experiment was conducted to study the effect of enzyme-treated soy protein (ETSP) in different nutrient density diets on performance, egg quality, digestive enzyme activity and mRNA expression of amino acid transporters of laying hens. A total of 1 200 Lohmann laying hens (52 wk of age) was randomly divided into a 3 × 2 factorial design that included three nutrient levels: [positive control (PC), metabolisable energy (ME): 2 680 kcal/kg, CP: 15.5%; negative control 1 (NC1), ME: 2 630 kcal/kg, CP: 15%; negative control 2 (NC2), ME:2 580 kcal/kg, CP: 14.5%] and 2 ETSP levels (0 and 0.5%) for 12 weeks. Each treatment had 10 replicates with 20 birds. With the decrease of dietary nutrition density, egg production rate (P = 0.07) and feed conversion ratio (FCR) (P = 0.06) were reduced. Yolk colour was decreased, and yolk index was increased. Supplemented ETSP improved FCR (P = 0.05) and qualified egg rate (P < 0.05). The mass loss rate of egg was decreased after storage for 30 days (P < 0.05). An interaction between nutrient density and ETSP was observed on albumen height and Haugh unit (P < 0.05), and the effects were most noticeable in hens fed 0.5% ETSP in NC2 group. An increase in the activity of trypsin in duodenum (P < 0.05) and the relative expressions of jejunum peptide transporter 1 (PepT1) (P < 0.05) and B0 system neutral amino acid transport carrier (B0AT) mRNA (P < 0.01) was observed during ETSP supplementation. The nutrient density and ETSP supplementation had no significant effect on microbiota in the cecal contents. Overall, the results in this study indicated that the ME decreased 100 kcal/kg and CP decreased 1% in diet of laying hens had a decreasing trend on production performance, no effects on enzyme activity, amino acid transporter mRNA, and gut microbiota, whereas 0.5% ETSP can increase activity of trypsin, PepT1 and B0AT mRNA relative expressions, and improve FCR, qualified egg rate.

Effect of different concentrations of neohesperidin dihydrochalcone on performance, egg quality, serum biochemistry and intestinal morphology in laying hens.

In recent years, neohesperidin dihydrochalcone (NHDC), as a class of natural flavonoids, has received more and more attention in nutrition research. However, the research on the application of NHDC in the laying hens is rarely reported. This study was conducted to determine the effects that different concentrations of dietary NHDC have on the production performance, egg quality, serum biochemistry and intestinal morphology of laying hens. A total of 240 Lohmann commercial laying hens (66 wk old) were divided into 4 groups, with each group's diet containing a different concentration of NHDC (0, 100 mg/kg, 200 mg/kg, and 400 mg/kg). Significant associations were found between NHDC consumption and both higher egg production (P = 0.050) and lower FCR (P = 0.028) after 12 wk NHDC feed. At 12 wk, eggs produced by hens consuming a 200 mg/kg NHDC diet had significantly thicker eggshells (P = 0.059) than those produced by hens consuming a 400 mg/kg diet. Dietary NHDC addition improved albumen height and Haugh unit after 15 d of storage (P < 0.01). However, no significant associations between NHDC consumption and these factors were identified after 12 wk. Dietary NHDC addition had no significant effects apparent of gel properties at 12 wk. In addition, NHDC can effectively reduce the content of total cholesterol (TC) (P = 0.042) and Groups treated with 100 mg/kg NHDC supplementation showed significantly increased T-AOC concentrations compared to control (P = 0.013) in serum. Hens fed an NHDC-supplemented diet exhibited a longer villus height and a higher villus/crypt ratio in the ileum (P < 0.01) as compared to controls, as well as lower crypt depth in the duodenum, jejunum and ileum. These results indicate that, as compared to a control diet, an NHDC-supplemented diet results in higher egg production and quality, as well as improvement in egg gel properties, serum biochemistry and intestinal morphology.

The impacts of egg storage time and maternal dietary vitamin E on the growth performance and antioxidant capacity of progeny chicks.

Two trials were designed to investigate the impacts of egg storage time and maternal dietary vitamin E (VE) supplementation on the growth performance and antioxidant capacity of progeny chicks. In total 512 Ross 308 broiler breeder hens (71-wk-old) were assigned to 2 dietary VE treatments (6 and 100 mg/kg) for 14 wk. Progeny chicks used in trials 1 and 2 were originated from eggs laid at week 10 (stored 0 d) and week 8 (stored 14 d), and week 14 (stored 0 d) and week 12 (stored 14 d), respectively. The 4 groups in trial 1 consisted of 2 levels of maternal VE (6 and 100 mg/kg) and 2 egg storage time (0 and 14 d). The 8 groups in trial 2 consisted of 2 levels of maternal VE (6 and 100 mg/kg), 2 egg storage time (0 and 14 d) and progeny sex (male and female). In trial 1, egg storage decreased the body weight, the liver total superoxide dismutase and total antioxidant capacity of 21-day-old offspring (P < 0.05), and the body weight gain and feed intake from 8 to 21 d and 1 to 21 d (P < 0.05); and increased the serum and liver malonaldehyde (MDA) of 7-day-old offspring and the ratio of feed: gain (F/G) from 1 to 7 d (P < 0.05). Maternal VE (100 vs. 6 mg/kg) decreased the F/G from 1 to 7 d and increased the serum total superoxide dismutase of 21-day-old offspring (P < 0.05). In trial 2, egg storage decreased the body weight of 42-day-old offspring, and the body weight gain and feed intake from 22 to 42 d and 1 to 42 d (P < 0.05); and increased the serum and liver MDA of 21- and 42-day-old offspring (P < 0.05). Maternal VE (100 vs. 6 mg/kg) reduced the serum MDA of 7-day-old offspring (P < 0.05). Interactively, maternal VE (100 vs. 6 mg/kg) reduced the serum MDA of offspring originated from stored eggs (P < 0.05), but not for that of offspring originated from unstored eggs in the two trials. It can be concluded that egg storage (14 vs. 0 d) decreased the growth performance and antioxidant capacity of offspring, while maternal dietary VE (100 vs. 6 mg/kg) supplementation could partly alleviate the reduction of antioxidant capacity (except for growth performance) of offspring induced by egg storage for the early phase post-hatch.

Dietary resistant potato starch improves growth performance and feather development in Pekin ducks fed a low phosphorus diet.

This study investigated whether dietary resistant potato starch (RPS) inclusion could ameliorate the negative impact of a low nonphytate phosphorus (nPP) diet on growth performance, feather growth, feather follicles (FF) development, and carcass traits by improving nutrient utilization and cecal microbiome fermentation capacity in Pekin ducks. The experiment was performed with a 2 × 2 randomized block design with 2 levels of RPS (0 or 12%) and 2 levels of nPP (low or normal, low: 0.22% at 1-14 d and 0.18% at 15-35 d of age; normal: 0.40% at 1-14 d and 0.35% at 15-35 d of age) for a total of 4 treatments, each with 8 replicate pens per treatment of 12 birds per pen. As regards growth performance and carcass traits, RPS inclusion markedly increased (P < 0.05) BW of 14 and 35 d, BWG and FI of 1-14 d, 15-35 d, and 1-35 d as well as abdominal fat and breast meat percentage of 35 d in ducks fed low nPP diets; moreover, RSP inclusion significantly reduced (P < 0.05) mortality in ducks fed low nPP diets. As regards feather growth and follicles development of 35 d, RPS inclusion significantly increased (P < 0.05) the fourth primary feather length, absolute feather weight, and the density of primary FF in the back skin in ducks fed low nPP diets. In regard to nutrition utilization, RPS supplementation significantly increased (P < 0.05) the availability of DM, CP, and energy, as well as dietary AME at 35 d of age in ducks fed low nPP diets. However, RPS supplementation had no effect (P > 0.05) on the concentration of cecal short-chain fatty acids and the activities of cecal phytase and cellulase in ducks fed low nPP diets. These results indicate that RPS can improve nutrient availability to ameliorate the negative effects on performance and feather development caused by a low nPP diet in Pekin ducks.

Vitamin E improves antioxidant status but not lipid metabolism in laying hens fed a aged corn-containing diet.

OBJECTIVE: The objective of this study was to determine whether a dietary vitamin E (VE) supplement could alleviate any detrimental effects of aged corn on lipid metabolism and antioxidant status in laying hens. METHODS: The experiment consisted of a 2×3 factorial design with two corn types (normal corn and aged corn (stored for 4 yr) and three concentrations of VE (0, 20, and 100 IU/kg). A total of 216 Lohmann laying hens (50 wk of age) were randomly allocated into six treatment diets for 12 wk. Each treatment had 6 replicates of 6 hens per replicate. RESULTS: The results show that aged corn significantly decreased the content of low-density lipoprotein cholesterol (p<0.05), and reduced chemokine-like receptor 1 (CMKLR1) mRNA expression (p<0.05) in the liver compared to controls. Diet with VE did not alter the content of crude fat and cholesterol (p>0.05), or acetyl-CoA carboxylase, lipoprotein lipase, fatty acid synthase or CMKLR1 mRNA expression (p>0.05) in the liver among treatment groups. Aged corn significantly increased the content of malondialdehyde (MDA) (p<0.05) and decreased superoxide dismutase (SOD) activity (p<0.05) in the liver. The VE increased the content of MDA (p<0.05) but decreased glutathione peroxidase (GSH-Px) activity in serum (p<0.01) and in the ovaries (p<0.05). Adding VE at 20 and 100 IU/kg significantly increased GSH-Px activity (p<0.05) in liver and in serum (p<0.01), 100 IU/kg VE significantly increased SOD activity (p<0.05) in serum. Aged corn had no significant effects on GSH-Px mRNA or SOD mRNA expression (p<0.01) in the liver and ovaries. Addition of 100 IU/kg VE could significantly increase SOD mRNA expression (p<0.01) in the liver and ovary. CONCLUSION: Aged corn affected lipid metabolism and decreased the antioxidant function of laying hens. Dietary VE supplementation was unable to counteract the negative effects of aged corn on lipid metabolism. However, addition of 100 IU/kg VE prevented aged corninduced lipid peroxidation in the organs of laying hens.

Protease supplementation attenuates the intestinal health damage caused by low-protein diets in Pekin ducks.

The objective of this study was to investigate the effects of low-protein diets with low digestibility of feed ingredients on intestinal damage and to explore whether the protease supplementation can alleviate the damage in Pekin ducks. A total of 576 Pekin ducklings (6 replicate pens, 16 ducks/pen) were randomly assigned to 6 dietary treatments (3 × 2 factorial arrangement) in a randomized complete block design. Factors were CP levels (13.5%, 15.5%, and 17.5%) and protease (0 or 20,000U/kg). Compared with the diets containing 17.5% CP, low-protein diets (13.5% CP) showed suppressed (P < 0.05) growth performance and feed intake (FI); reduced (P < 0.05) serum-free arginine, isoleucine, leucine, methionine, phenylalanine, valine, and proline as well as the cecal acetate and propionate concentration; increased (P < 0.05) plasma and ileal mucosal tumor necrosis factor-α (TNF-α) concentration; and downregulated (P < 0.05) mRNA expression of TNF-α, nuclear transcription factor-κb, interferon gamma, and Occludin in ileal mucosa. Irrespective of the dietary CP levels, protease supplementation significantly increased (P < 0.05) the serum-free glutamic acid concentration while decreasing (P < 0.05) the plasma endotoxin, IL-6, and the cecal isovalerate concentration. A significant interactive effect was observed between low-protein diets and protease supplementation (P < 0.05) on serum-free arginine concentration, the ratio of ileal villus height to crypt depth, and the IL-6 concentration in ileal mucosa. These results indicated that low-protein diets could damage intestinal integrity to induce systemic inflammation response and at last to suppress growth performance. Protease supplementation could partly attenuate the negative effects on gut health caused by low-protein diets in Pekin ducks.

Effects of graded levels of phytase supplementation on growth performance, serum biochemistry, tibia mineralization, and nutrient utilization in Pekin ducks.

A total of 560 one-day-old Pekin ducks were randomly allocated to 7 treatments with 8 replicate cages of 10 ducks per cage. The treatments included a corn-rice bran-soybean meal-based diet with recommended nonphytate phosphorus (NPP) (0.40% for 1-14 D/0.35% for 15-35 D, positive control; PC), NPP-deficient diet (0.22% for 1-14 D/0.18% for 15-35 D, negative control; NC), and NC diets supplemented with different levels of phytase (500, 2,500, 5,000, 7,500, 10,000 FTU/kg). Compared with the PC diet, feeding the NC diet significantly decreased (P < 0.05) the bird growth performance, serum total protein, and albumin concentration as well as tibia bone mineralization and strength and increased (P < 0.05) serum calcium (Ca), urea content, and alkaline phosphatase activity throughout the experimental period. Phytase supplementation to NC diets at 5,000 to 10,000 FTU/kg restored (P < 0.05) growth performance, serum biochemical parameters, and tibia traits when compared with the levels of the PC. Moreover, the addition of phytase linearly increased (P < 0.05) dietary protein, Ca, and phosphorus (P) utilization as well as nitrogen output, and excreta iron, copper, manganese, and zinc concentration quadratically increased (P < 0.05) as well as P output. In conclusion, phytase at ≥5,000 FTU/kg was effective in ameliorating the negative effects of NC diets and reducing trace mineral supplementation in diet of Pekin ducks.

Effects of dietary protein levels and protease supplementation on growth performance, carcass traits, meat quality, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet.

This study aimed to investigate to the effects of dietary CP levels and protease supplementation on growth performance, carcass traits, meat quality, nutrients utilization, and standardized ileal digestibility of amino acid in Pekin ducks fed a complex diet. A total of 960 14-day-old male ducks were weighed and randomly allotted to a 2 × 5 factorial arrangement of 10 treatments with 6 replicate pens per treatment and 16 ducks per pen fed to 49 D of age. Experimental factors included five dietary CP levels ranging from 13.5 to 17.5% and with or without protease (200 mg/kg) supplementation. Between day 28 to 34, the digestible and metabolizable trials were performed. Significant CP × protease interactions (P < 0.05) on breast meat yield, DM, energy and nitrogen utilization, as well as standardized ileal digestibility values of 7 amino acids were observed. Regardless of protease supplementation, ducks fed 13.5, 14.5, and 15.5% CP had a poorer (P < 0.05) growth performance and breast meat yield than ducks fed with 16.5 and 17.5% CP. Ducks fed 13.5% CP had a positive effect (P < 0.05) on meat quality, dietary DM, energy and nitrogen utilization as well as standardized ileal digestibility of amino acids. Protease supplementation increased (P < 0.05) DM and phosphorus retention and decreased (P < 0.05) shear force of breast meat, regardless of CP level; when CP = 14.5%, protease significantly increased (P < 0.05) breast muscle yield. The optimal CP requirement without or with protease supplementation for BWG and FI were 17.02 or 16.53% and 16.64 or 16.75%, respectively, based on linear broken-line regression.

Effect of dietary 25-hydroxycholecalciferol on the sternal mass of meat ducks under different vitamin regimens.

Genetic selection and intensive nutrition for increased growth rate in meat-type ducks has resulted in an imbalance between pectorales increment and sternal mass, which is detrimental to productivity and welfare. Reducing body weight and increasing sternal mass probably reverses these adverse effects. Therefore, 2 experiments (Expt.) were conducted to investigate the effects of 25-hydroxycholecalciferol (25-OH-D3), a vitamin D3 metabolites, on sternal mass. In Expt. 1, 512 1-day-old male ducks were randomly assigned to 4 low-nutrient density diets and received following treatments in a 2 × 2 factorial arrangement: (i) NRC or China Agricultural industry standards (NY/T) vitamin premixes and (ii) 0.069 mg/kg 25-HyD in feed or not. At 49 D of age, regardless of 25-OH-D3, NY/T vitamin regimen inhibited bone turnover and consequently increased sternal trabecular bone volume and mineral deposition compared with NRC vitamin premix. Supplementing 25-OH-D3 to NRC but not NY/T vitamin regimen significantly improved sternal microarchitecture and mineral content, which companied by decreased serum bone resorption markers concentration, as well as downregulation of the gene expressions of osteoclast differentiation and activity. In Expt. 2, 256 1-day-old male ducks were fed a standard nutrient density diet contained NRC vitamin premix with 0 or 0.069 mg/kg of 25-OH-D3. Results also showed that 25-OH-D3 treatment significantly improved sternal mineral accumulation and microarchitecture, along with decreasing osteoblast and osteoclast numbers in bone surface, declining serum bone turnover markers levels, and increasing serum Ca concentration. Collectively, these findings indicated that the dietary administration of 25-OH-D3 increased sternal mass in NRC vitamin diet by suppressing bone resorption in 49-day-old meat duck.

Evaluation of the standardized ileal digestibility of amino acids of rapeseed meals varying in protein solubility for Pekin ducks.

This study was conducted to determine whether protein solubility (PS) of rapeseed meals (RSM) can affect standardized ileal amino acid digestibility (SIDAA) in meat ducks. A total of 1,168, 14-days-old ducks were randomly allotted to 23 treatments (6 cages per diet, 8 ducks per cage) and 1 nitrogen-free diet treatment (8 cages, 8 ducks per cage) based on body weight. The 23 experimental diets consisted of a corn-soybean meal basal diet, and 22 diets containing 15% RSM: 85% basal diet. Titanium dioxide (0.5%) was included in all diets as an indigestible marker. On day 18, all ducks were euthanized by carbon dioxide asphyxiation and digesta samples from the ileum. The contents of PS, ether extract (EE), glucosinolate, isothiocyanate, and oxazolidine were significantly different (P < 0.05) in the 22 RSM, with the CV being 52.62, 49.23, 86.84, 90.19, and 81.98%, respectively. The content of lysine (Lys) and methionine in the 22 RSM samples ranged from 1.03 to 2.71% (CV 24.19%) and from 0.33 to 0.65% (CV 15.17%), respectively. The SIDAA, except for leucine (Leu) and tyrosine, of the 22 RSM samples varied significantly (P < 0.05). A positive correlation was observed (P < 0.05) between PS and standardized ileal digestibility (SID) of Lys, isoleucine, valine, phenylalanine, histidine, serine, cysteine, and tyrosine. The R2 value of multiple linear regression equations for predicting the SID of amino acids (AA) was best for Lys (R2 = 0.958 using dry matter, crude protein, EE, crude fiber, acid detergent fiber, and PS) and least significant for Leu (R2 = 0.348 using crude fiber and ash) with intermediate values for other AA (R2 = 0.359-0.837, P < 0.05). These results suggest that PS varying from 15.06 to 98.08%, also varied considerably in the proximate nutrient content, AA composition, and antinutritional factor content, which was reflected in considerable differences in the duck's SID of AA in RSM. Therefore, PS value can partly reflect the quality of RSM.

Different microbiomes are found in healthy breeder ducks and those with foot pad dermatitis.

Foot pad dermatitis (FPD) is a serious problem of the modern poultry industry, negatively affecting birds' welfare and health status, walking and feeding activity, growth performance, carcass quality, and economic performance of meat production. The gut microbiome in poultry with FPD has not been previously investigated. Therefore, we compared the cecal microbiomes of 8 breeding ducks with FPD to 8 control ducks (breeders with apparently healthy feet) by pyrosequencing the bacterial 16S ribosomal RNA gene. The results showed a significant ß-diversity (P < 0.05) of cecal microbiota presented between healthy and FPD-affected breeder ducks. The plasma endotoxins, interleukin 1ß (IL-1ß), IL-17, IL-6, IL-10, and tumor necrosis factor-α concentration, and the abundance of class Clostridia in FPD-affected ducks was markedly higher (P < 0.05), however, the abundance of genus Prevotella, Lactobacillus, Lachnospiraceae UCG-008, and the Firmicutes to Bacteroidetes ratio in FPD-affected ducks was significantly lower (P < 0.05) when compared to healthy ducks. These findings suggest when duck breeders are affected with FPD, ducks show an increased inflammatory response and a difference of structure and composition of the cecal microbiome.

Effect of dietary graded resistant potato starch levels on growth performance, plasma cytokines concentration, and intestinal health in meat ducks.

The objective of the present study was to investigate the effect of dietary graded raw potato starch (RPS) levels on growth performance, plasma cytokines concentration, ileal barrier function, and cecal short-chain fatty acids (SCFA) concentration in meat ducks from 1 to 35 D of age. This study included 2 experiments. In experiment (Exp.) 1, sixteen 35-day-old meat ducks were used to evaluate the AME of RPS by orogastric administration. Results showed the AME value of RPS on ducks is 2.76 kcal/g. In Exp. 2, a total of 600 one-day-old ducklings were randomly assigned to 5 isonitrogenous and isoenergetic dietary treatments that included 0 (control), 6, 12, 18, and 24% RPS, respectively. Samples were collected at both of 14 and 35 D. Neither growth performance nor ileal parameters (length, weight, and pH) at both of 14 and 35 D was affected by dietary RPS. However, the mucosal thickness (14 D), villus height (except for 18% RPS at 14 D), and the villus height: crypt depth ratio (14 and 35 D) of the ileum were increased in the 12 and 18% RPS diets when compared to 0% RPS diet. Meanwhile, proinflammatory factors such as plasma interleukin (IL)-1ß and IL-6 (14 D) reduced in 12% RPS diet and tumor necrosis factor α decreased in 12% (except for 14 D) and 18% RPS groups. When compared with the control group, diets with 18% RPS significantly increased mucin 2 gene expression at 14 D, and 12% RPS elevated the mRNA expression of tight junction proteins including Zonula occludens-1 and Claudin 1 (except for 14 D) in the ileal mucosa of birds. Furthermore, ducks fed 12% RPS diet had higher concentrations of acetate, propionate, and butyrate in cecal digesta than other groups. These findings indicated that diets with 12 and/or 18% RPS increased the cecal SCFA concentration, which subsequently enhanced the barrier function and improved intestinal health in the ileum for 14 and 35-day-old meat ducks.