Automatic Perception of Typical Abnormal Situations in Cage-Reared Ducks Using Computer Vision.

Overturning and death are common abnormalities in cage-reared ducks. To achieve timely and accurate detection, this study focused on 10-day-old cage-reared ducks, which are prone to these conditions, and established prior data on such situations. Using the original YOLOv8 as the base network, multiple GAM attention mechanisms were embedded into the feature fusion part (neck) to enhance the network's focus on the abnormal regions in images of cage-reared ducks. Additionally, the Wise-IoU loss function replaced the CIoU loss function by employing a dynamic non-monotonic focusing mechanism to balance the data samples and mitigate excessive penalties from geometric parameters in the model. The image brightness was adjusted by factors of 0.85 and 1.25, and mainstream object-detection algorithms were adopted to test and compare the generalization and performance of the proposed method. Based on six key points around the head, beak, chest, tail, left foot, and right foot of cage-reared ducks, the body structure of the abnormal ducks was refined. Accurate estimation of the overturning and dead postures was achieved using the HRNet-48. The results demonstrated that the proposed method accurately recognized these states, achieving a mean Average Precision (mAP) value of 0.924, which was 1.65% higher than that of the original YOLOv8. The method effectively addressed the recognition interference caused by lighting differences, and exhibited an excellent generalization ability and comprehensive detection performance. Furthermore, the proposed abnormal cage-reared duck pose-estimation model achieved an Object Key point Similarity (OKS) value of 0.921, with a single-frame processing time of 0.528 s, accurately detecting multiple key points of the abnormal cage-reared duck bodies and generating correct posture expressions.

Effects of residual feed intake on the economic traits of fast-growing meat ducks.

Feed efficiency (FE) is a crucial economic indicator of meat duck production. The objective of this study was to assess the impact of residual feed intake (RFI), defined as the difference between the actual and expected feed intake based on animal's production and maintenance requirements, on the growth performance (GP), slaughter and internal organ characteristics of fast-growing meat ducks. In total, 1,300 healthy 14-day-old male fast-growing meat ducks were housed in individual cages until slaughter at the age of 35 d. The characteristics of the carcass and internal organs of 30 ducks with the highest RFI (HRFI) and the lowest RFI (LRFI) were respectively determined. RFI, the feed conversion ratio (FCR), and average day feed intake (ADFI) were significantly lower in the LRFI group than the HRFI group (P < 0.001), while there were no significant differences in marketing BW or BW gain (BWG) (P > 0.05). The thigh muscle and lean meat yields were higher, and the abdominal fat content was lower (P < 0.001) in the LRFI group, while there were no significant differences in other carcass traits between the groups (P > 0.05). The liver and gizzard yields were significantly higher (P < 0.001) in the LRFI group, while there were no significant differences (P > 0.05) in intestinal length between the groups. RFI was highly positively correlate with FCR and ADFI (P < 0.01), but negatively correlated the yields of thigh muscle, lean meat, liver, and gizzard, and positively correlated with abdominal fat content. These results indicate that selection for low RFI could improve the FE of fast-growing meat ducks without affecting the marketing BW and BWG, while increasing yields of thigh muscle and lean meat and reducing abdominal fat content. These findings offer useful insights into the biological processes that influence FE of fast-growing meat ducks.

Gut-brain bidirectional determination in regulating the residual feed intake of small-sized meat ducks.

The gut-brain axis is essential in maintaining the homeostasis of neuronal system, endocrine system, and intestinal microbiota in both the afferent and efferent directions. This axis is considered to be a key mechanism that regulates feed efficiency (FE). This study aimed to investigate the regulatory mechanisms of gut-brain axis-related genes on the residual feed intake (RFI) in H-strain small-sized meat ducks. A total of 500 ducks with similar initial BW (635.2 ± 15.1 g) were selected and reared in the same experimental facility until slaughter at 42 d of age. RFI was calculated from the average daily gain (ADG), average daily feed intake (ADFI), and metabolic body weight (MBW0.75). Thirty high-RFI (H-RFI) and 30 low-RFI (L-RFI) birds were selected for further evaluation of growth performance, carcass characteristics, and blood biochemical parameter measurements. Six L-RFI and 6 H-RFI birds were then subjected to hypothalamic transcriptomic and cecal microbial sequencing analyses. Results indicated that L-RFI birds exhibited lower production performance (ADFI, FCR, and RFI) and blood biochemical indices (total cholesterol and ghrelin content) compared with H-RFI birds (P < 0.05). Gene expression differed significantly between the L-RFI and H-RFI birds, with 70 upregulated and 50 downregulated genes. The bacterial communities of L-RFI birds showed higher abundances of Bacteroides, Bifidobacterium, and Lactococcus, and lower abundances of Erysipelatoclostridium, Parasutterella, Fournierella, and Blautia compared with H-RFI birds (P < 0.05). Interactive analysis revealed bacterial communities associated with FE were significantly correlated with hypothalamic genes (P < 0.05), for example, Bacteroides was positively correlated with DGKH and LIPT2, while negatively correlated with CAPN9, GABRD, and PDE1A. Bifidobacterium showed significant correlations with ATP2A3, CALHM6, and TMEM121B. Overall, RFI was a crucial indicator of FE, regulated by interactions between brain gene expression and gut microbiota through cAMP signaling, neuroactive ligand-receptor interaction, and calcium signaling pathways. Notably, increased expression of hypothalamic genes and abundance of carbohydrate-utilization microbiota in L-RFI meat ducks improved FE by enhancing energy metabolism and volatile fatty acids absorption.

Metagenomic insights into the relationship between intestinal flora and residual feed intake of meat ducks.

In this study, we sought to determine the effects of intestinal flora on the feed efficiency of meat ducks by evaluating the correlation between intestinal flora and residual feed intake. The F2 generation of Cherry Valley ducks × Runzhou Crested White ducks was used as the study subjects, and feed consumption being recorded from d 21 to 42. RFI was calculated based on growth performance, and 20 low RFI and 20 high RFI ducks were randomly selected to characterize the effect of RFI on growth performance. To analyze the intestinal flora affecting RFI, 16s rDNA sequencing was performed on the contents of 5 intestinal segments from the HR and LR groups, and macrogenomic sequencing was performed on the cecal contents. Feed intake, average daily feed intake, feed conversion ratio, and residual feed intake were lower in low RFI. Analysis of the intestinal flora revealed the cecum to be more highly enriched in the carbohydrate metabolism pathway and less enriched with potentially pathogenic taxa than the other assessed intestinal regions. Further analysis of the cecal microbiota identified nine significantly differentially enriched intestinal flora. In this study, we accordingly identified a basis for the mechanisms underlying the effects of the intestinal flora on meat duck feed efficiency.

Dietary ethylenediamine dihydroiodide mitigated Escherichia coli O78-induced immune and intestinal damage of ducks via suppression of NF-κB signal.

This study investigated the effect of Ethylenediamine dihydroiodide (EDDI) on growth performance, immune function and intestinal health of meat ducks challenged with Avian pathogenic Escherichia coli (APEC). A total of 360 one-day-old Cherry Valley ducks with similar body weight were randomly allocated to 6 treatments (6 floor cages, 10 birds/cage). A 3 × 2 factor design was used with 3 dietary iodine levels (0, 8, 16 mg/kg in the form EDDI and whether APEC was challenged or not at 7-day-old ducks. The feeding period lasted for 20 d. The results showed that the addition of EDDI reduced APEC-induced decrease of the 20-d weight loss of meat ducks (P < 0.05), and alleviated the inflammatory response of liver tissue induced by APEC challenge in meat ducks. In terms of immune function, EDDI supplementation reduced the immune organ index and increased the immune cell count of meat ducks, reduced the level of endotoxins in the serum of meat ducks (P < 0.05), as well as inhibited the expression levels of liver and spleen inflammatory factors and TLR signaling pathway related genes induced by APEC (P < 0.05). In terms of intestinal health, EDDI inhibited APEC-induced decreases in ZO-3 genes expression and increases in IL-1ß and TNF-α expression, increased relative abundance of beneficial bacteria in the cecum and content of metabolites. Pearson correlation analysis showed that there was a significant correlation between liver inflammatory factors and TLR4 signaling pathway genes, and there might be a significant correlation between intestinal microbial flora and other physiological indexes of meat ducks, which indicated that EDDI could reduce the damage to immune function and intestinal health caused by APEC challenge through regulating the structure of intestinal flora. Collectively, our findings suggest that the EDDI can promote growth performance, improve immune function and the intestinal barrier in APEC-challenged meat ducks, which may be related to the suppression of NF-κB signal.

Effects of lysophospholipids and multi-enzymes on growth performance, antioxidant capacity, intestinal health, and cecal microflora of male cherry valley ducks.

Improvement of nutrient utilization to promote growth performance is always pursued in poultry. In this study, a total of 360 1-d-old male ducklings was randomly assigned to 3 treatments in terms of diet treatment groups. Three treatments were as follows: basal diet (Con group) or basal diet supplemented with 300 mg/kg multi-enzymes (ENZ group) or 500 mg/kg lysophospholipids (LPL group). On day 42, ducks were slaughtered for samplings. The results revealed that supplementary LPL improved the body weight (BW) at day 14 and average daily gain (ADG) during days 1 to 14 and improved the feed conversion rate (FCR) for the overall period (P < 0.05) by improving nutrient utilization of dry matter and ether extract (P < 0.05) compared with the Con group. Dietary ENZ improved the FCR from days 15-42 and 1-42, and nitrogen utilization (P < 0.05) compared with the Con group. Jejunal villus height and villus height/crypt depth ratio were higher (P < 0.05) in the LPL group and tended to be higher (P < 0.1) in the ENZ group compared to the Con group. Supplementation with either LPL or ENZ reduced interleukin-1ß concentration in jejunal mucus (P < 0.05). Both LPL and ENZ enhanced serum total superoxide dismutase activity (P < 0.05), whereas only supplementation with LPL elevated total antioxidant capacity (P < 0.05). In terms of cecal microbiota, microbial richness tended to be reduced by LPL, with low observed-OTUs and Chao1 (0.05 < P < 0.1). Supplementation with ENZ led to higher abundances of cellulolytic bacteria such as Fibrobacterota, [Eubacterium]_xylanophilum_group, and Bifidobacterium. Overall, both LPL and ENZ improved FCR, which may be relevant to ameliorative intestinal health, overall antioxidant ability, and cecal microbiome.

Well known in the industry, enhancing nutrient utilization in meat ducks is a vital sustainability tactic to manage production costs. This is especially relevant because meat ducks require more feed, and grain prices are on the rise. Lysophospholipids (LPL) have been confirmed to effectively emulsify fat, which boosts fat utilization. Additionally, multi-exogenous enzymes (ENZ) play a significant role in nutrient breakdown. Our feeding experiment on Cherry Vallery male ducks demonstrated that a dietary supplement of LPL at 500 mg/kg improves the body weight, average daily gain, and feed conversion rate during the starter period. It also elevates the feed conversion rate over the entire period, enhances ether extract utilization, and positively impacts jejunal morphology development in the finishing phase. However, LPL negatively affects the α-diversity of cecal flora. On the other hand, supplementing with 300 mg/kg ENZ improves the feed conversion rate throughout the period, increases nitrogen utilization in the finisher phase, diminishes interleukin-1ß levels in the jejunum, elevates superoxide dismutase in the serum, and promotes the prevalence of cellulolytic bacteria. In summary, feed supplemented with 500 mg/kg LPL and 300 mg/kg ENZ aids in reducing the FCR of meat ducks.

Growth performance, carcass traits, meat quality, and blood variables of small-sized meat ducks with different feed efficiency phenotypes.

The study investigated the effects of feed efficiency (residual feed intake, RFI and residual intake and gain, RIG) on the production performance of small-sized meat ducks. Ninety ducks with intermediate and extreme (high and low) RFI values were selected from 1,083 male ducks of similar body weight, and the 3 groups were then redivided according to RIG. For both efficiency measures, the feed conversion ratio (FCR) and average daily feed intake (ADFI) of efficient ducks were significantly lower than those of inefficient ducks (P < 0.05), while the residual body weight gain (RG) was significantly higher in efficient ducks (P < 0.05). Inefficient-RFI animals showed greater skin fat yield (P < 0.05), but no other differences in carcass traits were observed (P > 0.05). RIG had positive effects on the pH1 value of the breast muscle (P < 0.05), but feed efficiency did not affect the other meat quality traits (P > 0.05). With regard to blood biochemical parameters, efficient ducks had significantly lower triglycerides (TG) (P < 0.05). Correlation analysis demonstrated that RFI was positively correlated with average daily feed intake and feed conversion ratio (P < 0.05), while RIG exhibited a strong negative correlation with both (P < 0.05). The average daily body weight gain was positively correlated with RIG (P < 0.05). RIG had a positive effect on the pH1 value of the breast muscle (P < 0.05). Furthermore, triglyceride and high-density lipoprotein cholesterol levels correlated with both efficiency classifications (P < 0.05). Overall, the efficiency measures did not affect the carcass and meat quality of small-sized meat ducks but could identify ducks with lower feed consumption and fast growth.

Effects of Dietary Zinc Deficiency on Skin Breaking Strength and Fatty Acid Composition in Broiler Chickens and Pekin Ducks.

This study is aimed at investigating the effect of dietary zinc deficiency (ZnD) on skin breaking strength and skin chemical and fatty acid composition in broiler chickens and Pekin ducks. A total of 200 1-day-old male broiler chickens and 200 1-day-old male ducklings were used in a 2 × 2 factorial design and randomly allocated to 4 treatments with 10 replicated cages of 10 birds per cage. Diets containing zinc at 84.77 mg/kg and 20.42 mg/kg were regarded as the control diet and zinc-deficient diet, respectively. The results showed the following: (1) dietary ZnD decreased (P < 0.05) the breast skin weight (day 21), breast skin index (day 21), skin fat content (day 7), and skin Zn content (days 7, 14, and 21) of ducks, but only increased (P < 0.05) the skin fat content of broiler chickens at 7 days of age; ducks had a higher (P < 0.05) breast skin weight, breast skin index, and skin breaking strength as well as a lower skin fat content (days 7 and 14) than those in broiler chickens. (2) Dietary ZnD decreased the content of myristic acid (day 21) and increased the content of oleic acid (day 7) content in the skin of ducks and increased the palmitic acid (day 7) content in the skin of broiler chickens (P < 0.05) and increased the MUFA (day 7) content in the skin and the atherogenic index (day 21) in ducks. The contents of myristic acid (day 21), stearic acid (day 21), and oleic acid (days 7, 14, and 21) in the skin of broiler chickens were lower (P < 0.05) than those in ducks of the same age. In conclusion, using skin weight, skin index and skin MUFA content as criteria, the results indicated that meat ducks were more sensitive to dietary ZnD than broiler chickens. Using skin fat content as criterion, the results indicated that broiler chickens were more sensitive to dietary ZnD than meat ducks.

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

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

MYOZ1 Gene Promotes Muscle Growth and Development in Meat Ducks.

To explore the effect of MYOZ1 in the muscle growth and development of meat ducks, MYOZ1 single-nucleotide polymorphism loci were screened at the DNA level in the meat duck population with highest and lowest feed conversion rates. The expression of MYOZ1 was detected using reverse-transcription quantitative polymerase chain reaction. The protein expression of MYOZ1 was detected using Western blotting at the protein level. The results showed that there was a base mutation site at 30 bp and 158 bp in the fourth exon of MYOZ1, which was mutated from C to T (exon4 C30T) and from G to A (exon4 G158A), respectively. The allele frequency of the locus was significantly different between the high and low feed conversion rate groups (p < 0.01). The relative expression of MYOZ1 mRNA in breast muscle tissue of HF ducks was significantly higher than that of LF ducks (p < 0.01). The MYOZ1 protein expression of HF ducks was significantly higher than that of LF ducks (p < 0.01). In general, MYOZ1 has a positive regulatory effect on the muscle growth and development of meat ducks. The results of this study lay a certain theoretical basis for the muscle growth and development of meat ducks.

Calcium supplementation in low nutrient density diet for meat ducks improves breast meat tenderness associated with myocyte apoptosis and proteolytic changes.

To define the relationship between dietary nutrient density, calcium (Ca), and meat quality in meat ducks. A total of 288 male Cherry Valley SM3 medium ducklings were fed a common standard starter diet until d 14. At 15 d of age, ducks were randomly divided into 2 treatment groups and fed either a conventional diet or a low nutrient density (LND) diet. Compared with the conventional diet, the energy was reduced in the LND diet by 8.6% and 16.8% in grower (15 to 35 d) and finisher (36 to 56 d) phases, respectively, while other essential nutrients were kept proportionate to energy. The LND diet decreased the shear force (P < 0.05) and increased the lightness values of the pectoralis muscle when compared to the conventional diet, suggesting that LND diet exerted a beneficial role in meat quality. Subsequently, the effects of grated Ca in the LND diet on meat quality of pectoralis muscle were evaluated. A total of 576 male ducklings were fed a common starter diet until d 14, followed by feeding 4 LND diets with 0.5%, 0.7%, 0.9%, and 1.1% Ca. The results show that LND diets with 0.7% or more Ca decreased the shear force of pectoralis major muscle in 42-d-old meat ducks (P < 0.05). To explore the mechanism underlying Ca and tenderness, data from birds fed either 0.5% or 1.1% Ca in the LND diet indicated that birds fed 1.1% Ca exhibited lower shear force, upregulated calpains 1 expression, and higher calpains activity compared to those fed the LND diet with 0.5% Ca (P < 0.05). Moreover, the 1.1% Ca LND diet induced a higher myocyte apoptosis (P = 0.06) and upregulated mRNA expression of caspase-3 (P = 0.07) in breast muscle. Our data suggest that LND diets with 0.9% or 1.1% Ca had a positive role in the tenderness of breast meat, particularly the enhancing effect of 1.1% Ca LND diet on tenderness seems to be associated with proteolytic changes of myofibrillar proteins and myocyte apoptosis in meat ducks.

Effects of residual feed intake divergence on growth performance, carcass traits, meat quality, and blood biochemical parameters in small-sized meat ducks.

Feed efficiency (FE) is a major economic trait of meat duck. This study aimed to evaluate the effects of residual feed intake (RFI) divergence on growth performance, carcass traits, meat quality, and blood biochemical parameters in small-sized meat ducks. A total of 500 healthy 21-day-old male ducks were housed in individual cages until slaughter at 63 d of age. The growth performance was determined for all the ducks. The carcass yield, meat quality, and blood biochemical parameters were determined for the selected 30 high-RFI (HRFI) and 30 low-RFI (LRFI) ducks. In terms of growth performance, the RFI, feed conversion ratio (FCR), and average daily feed intake (ADFI) were found to be significantly lower in the LRFI group (P < 0.01), whereas no differences were observed in the BW and body weight gain (P > 0.05). For slaughter performance, no differences were observed in the carcass traits between the LRFI and HRFI groups (P > 0.05). For meat quality, the shear force of breast muscle was significantly lower in the LRFI group (P < 0.05), while the other meat quality traits of breast and thigh muscles demonstrated no differences (P > 0.05). For blood biochemical parameters, the serum concentrations of triglycerides (TG) and glucose (GLU) were significantly lower in the LRFI group (P < 0.05), while the other parameters showed no differences (P > 0.05). The correlation analysis demonstrated a high positive correlation between RFI, FCR, and ADFI (P < 0.01). The RFI demonstrated a negative effect on the breast muscle and lean meat yields, but a positive effect on the shear force of breast muscle (P < 0.05). Further, the RFI demonstrated a positive effect on the TG and GLU levels (P < 0.05). These results indicate that the selection for low RFI could improve the FE of small-sized meat ducks without affecting the production performance. This study provides valuable insight into the biological processes underlying the variations in FE in small-sized meat ducks.

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.

Zinc Methionine Improves the Growth Performance of Meat Ducks by Enhancing the Antioxidant Capacity and Intestinal Barrier Function.

This study was conducted to investigate the effects of zinc methionine (Zn-Met) on the growth performance, antioxidant capacity and intestinal barrier function of meat ducks. Three hundred and sixty 1-day-old male Cherry Valley ducks were randomly divided into 6 groups with 6 replicates (10 birds each), and fed diets with 0, 30, 60, 90, 120 or 150 mg/kg Zn for 35 d. The results indicated that dietary supplementation with Zn-Met substantially increased the average daily gain (ADG), and reduced the feed to gain ratio (F/G) during 1-35 d (P < 0.05). Dietary Zn-Met markedly increased the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH), and reduced the malondialdehyde (MDA) content in the jejunum (P < 0.05). The mRNA expression levels of critical antioxidant enzymes such as SOD, CAT, and nuclear factor erythroid 2-related factor 2 (Nrf2) were increased by Zn in the jejunum (P < 0.05). Supplementation with 60, 90, 120, and 150 mg/kg of Zn significantly reduced the diamine oxidase (DAO) activity in the serum (P < 0.05). Different levels of Zn can increase the mRNA expression of occluding (OCLN) and zonula occludens-1 (ZO-1) in the jejunum (P < 0.05). Diets supplemented with zinc significantly increased the content of mucin2 (MUC2), secretory immunoglobulin A (sIgA), immunoglobulin A (IgA) and immunoglobulin G (IgG) in the jejunum of meat ducks (P < 0.05). The 16S rRNA sequence analysis indicated that 150 mg/kg of Zn had a higher relative abundance of Verrucomicrobia and Akkermansia in cecal digesta (P < 0.05). In conclusion, Zn-Met improved the growth performance of meat ducks by enhancing intestinal antioxidant capacity and intestinal barrier function. This study provides data support for the application of Zn-Met in meat duck breeding.

Research Note: Effects of cage and floor rearing systems on growth performance, carcass traits, and meat quality in small-sized meat ducks.

This study was performed to evaluate the effects of different rearing methods on the growth performance, carcass yield, and meat quality of small-sized meat ducks. A total of 420 healthy 21-day-old birds was randomly allocated to 2 treatment groups (6 replicates per treatment, sex ratio 1/1) and subjected to 2 rearing methods (furnished cage and plastic wire-floor) until d 63. Growth performance was measured in all birds. Three males and 3 females from each replicate were randomly selected and evaluated to determine the carcass yield and meat quality. In terms of growth performance, the rearing method affected the final body weight, average daily feed intake, and average daily gain, which were higher in the cage group (P < 0.05) than in the floor group, with a similar feed/gain in both groups. For slaughter performance, ducks in the cage group showed a higher abdominal fat yield and lower gizzard yield than those in the floor group (P < 0.05). For meat quality, the L* value of the breast muscle was higher in the cage group than in the floor group (P < 0.05). The pH recorded at 1 h was lower and pH recorded at 24 h was higher in the cage group (P < 0.05). The shear force and water loss rate were both lower in the cage group (P < 0.05). Additionally, the moisture content was lower and intramuscular fat content was higher in ducks fed in cages (P < 0.05). Our results indicate that the cage rearing system improved the growth performance and meat quality of ducks, which is appropriate for small-sized meat ducks.

Effect of manganese supplementation on the carcass traits, meat quality, intramuscular fat, and tissue manganese accumulation of Pekin duck.

Manganese (Mn) is a trace element present in all tissues and is essential for animal growth and health; it also has an antioxidant capacity in tissues. The effect of Mn on meat quality and the mechanism of fat deposition of the breast muscle is still unclear. Therefore, the present study aimed to investigate the effect of Mn supplementation on the growth performance, meat quality, the activity and transcription of antioxidant enzymes, and fatty acid profile in the breast muscle, and the Mn deposition in tissues of Pekin ducks. A total of 896 one-day-old Pekin ducks were allocated into 7 groups, with 8 replicates, each replicate containing 16 ducks. The treatment diets consisted of basal diet supplemented with manganese sulfate at levels 30, 60, 90, 120, 150, 240 mg/kg (as Mn). Results showed that ducks fed diets supplemented with Mn had no effect on the growth performance but decrease in the feed-to-gain ratio of day 1-14 (P < 0.01). Dietary Mn increased significantly the a∗ (redness) value of the duck breast meat at 24 h and intramuscular fat (P < 0.05), and decreased drip loss and shear force of the breast meat (P < 0.05). Manganese supplement significantly reduced the malondialdehyde content (P < 0.05), and significantly increased the mRNA expressions of manganese superoxide dismutase, thioredoxin 2, peroxiredoxin 3, and catalase (P < 0.05). About the fatty acid profile, dietary Mn increased (P < 0.05) the proportions of the C20 family. Manganese accumulation in the heart, breast muscle, and tibia was increased with Mn supplementation (P < 0.05), and Mn content of the heart conforms to the quadratic curve. Besides, Mn supplementation notably increased mRNA expression in genes involved in lipogenesis and deposition and decreased in genes associated with lipolytic in the breast muscle. These findings reveal that dietary Mn could improve meat quality and enhance antioxidant activity and intramuscular fat, which via regulated gene expression involved in lipogenesis and lipolytic.

Dietary supplementation of 25-hydroxycholecalciferol increases tibial mass by suppression bone resorption in meat ducks.

Leg problems often result from the rapid weight gain and poor bone quality in modern ducks, leading to a high risk of fractures and continuous pain. We hypothesized that improving bone quality in combination with delaying weight gain via a low nutrient density (LND) diet probably reverses these skeletal abnormalities. Studies indicated that 25-hydroxycholecalciferol (25-OH-D3), a vitamin D3 metabolite, is effective in treating bone-related disorders. Therefore, Exp. 1 evaluated the effects of 25-OH-D3 on tibial mass of meat ducks. Male meat ducklings were fed a standard nutrient density diet (containing a regular vitamin regimen) without or with 25-OH-D3 at 0.069 mg/kg for 35 d. The results showed that 25-OH-D3 supplementation improved the mineral content, microarchitecture and mechanical properties of tibias, and this companied by a decreased serum bone resorption marker and a concomitant decrement in osteoclast-specific marker genes expression. Subsequently, Exp. 2 was conducted to examine the impacts of 25-OH-D3 incorporating an LND diet on tibial quality of ducks under 2 different vitamin regimens (regular and high). Ducklings were allocated to a 2 × 2 factorial arrangement with 2 kinds of vitamin premixes and without or with 25-OH-D3 at 0.069 mg/kg in LND diets. The high premix had higher levels of all vitamins except biotin than the regular premix. The results demonstrated that high vitamin diets exhibited more significant effects than regular vitamin diets on inhibiting bone turnover and increasing minerals deposition. Tibial mineral content, microarchitecture, and strength of birds under the regular vitamin regimen were increased by 25-OH-D3 supplementation; However, these positive effects were not observed in ducks under the high vitamin regimen. To conclude, 25-OH-D3 supplementation improves tibial mass by suppressing osteoclast-mediated bone resorption in meat ducks, and this positive impact only was observed in regular but not high vitamin regimen when birds fed an LND diet.

A joint analysis strategy reveals genetic changes associated with artificial selection between egg-type and meat-type ducks.

Egg-type ducks and meat-type ducks are predominantly commercial or indigenous and have been subjected to artificial directional selection. These two duck types differ substantially in body shape, production performance and reproductivity. However, the genetic changes associated with phenotypic differences remain unclear. Here, we compared the two duck types at the genomic and transcriptomic levels. We identified a large number of SNPs and genes in genomic divergent regions in terms of FST and θπ values. The corresponding genes were mainly enriched in embryonic development function and metabolic pathway. RNA-seq analysis also revealed differential gene expression in the liver and gonads. The differentially expressed genes were functionally associated with signal transmission and substance metabolism respectively. Furthermore, we found that seven genes were related to differentiation between the two types by both g genome and transcriptome analysis and were plausible candidate genes. These genes were annotated to GO categories of cell development and disease immunity. These findings will enable a better understanding of the artificial selection history of meat and egg ducks and provide a valuable resource for future research on the breeding of these two lineages.

Occurrence and Molecular Characteristics of Mcr-1-Positive Escherichia coli from Healthy Meat Ducks in Shandong Province of China.

Colistin has been used as a growth promotant in livestock feed for many years. In China, mcr-1-positive Escherichia coli strains have been isolated from humans, chickens, and pigs. To date, there are few reports about the prevalence and molecular characteristics of fecal E. coli bearing mcr-1 in the meat ducks. In this study, the prevalence of mcr-1 gene was investigated among 120 fecal E. coli strains isolated from healthy meat ducks in Shandong province of China between October 2017 and February 2018. A total of nine mcr-1-containing E. coli strains were identified and two were identified as extra-intestinal pathogenic E. coli (ExPEC) among them. The clonal relationship of the nine E. coli strains was determined by multilocus sequencing typing (MLST) and pulsed field gel electrophoresis (PFGE), and the results indicated that all mcr-1-carrying isolates were clonally unrelated. Two different genetic contexts of mcr-1 were identified among these isolates. Colistin-resistant phenotype of all the isolates was successfully transferred to the recipient strains by conjugation experiments and seven transconjugants carried a single plasmid. The mcr-1 was located on three replicon plasmids: IncI2 (n = 4), IncFII (n = 2) and IncN (n = 1). Complete sequence analysis of a representative plasmid pTA9 revealed that it was strikingly similar with plasmid pMCR1-IncI2 of E. coli, plasmid pHNSHP45 of E. coli, and plasmid pWF-5-19C of Cronobacter sakazakii, implying that pTA9-like plasmids may be epidemic plasmids that mediate the spread of mcr-1 among Enterobacteriaceae. These results highlight that healthy meat duck is a potential reservoir for multidrug resistant mcr-1-containing E. coli strains.

Research Note: Effects of the rearing method and stocking density on carcass traits and proximate composition of meat in small-sized meat ducks.

The present study was conducted to evaluate the effects of different rearing methods and stocking densities on carcass yield and proximate composition of meat in small-sized meat ducks. A total of 555 one-day-old birds were randomly allocated to six treatment groups (three replicates per treatment, sex ratio 1/1) with a 2 × 3 factorial arrangement of two rearing methods (reared in cage or net) and three stocking densities (5 [low], 7 [medium], or 9 [high] birds/m2) until day 70. Five male and five female birds from each replicate were randomly selected and processed to determine the carcass yield. Proximate composition was determined by proximate analysis using the breast and thigh muscles. There was no interaction effect between the rearing method and stocking density on carcass yield. The rearing method affected the thigh muscle rate, which was higher in the cage groups (P < 0.05). The final BW and abdominal fat rate decreased with increasing density (P < 0.05), whereas the thigh muscle rate increased (P < 0.05). There were significant interaction effects (P < 0.05) between the rearing method and stocking density on the content of protein, fat, and collagen. The content of fat and moisture was greater and lower, respectively, in the cage groups (P < 0.05). The content of moisture, fat, and collagen with a medium density was higher (P < 0.05). In addition, the content of protein and fat was lower in the ducks fed in nets at low and high densities (P < 0.05), respectively; the collagen content of breast and thigh muscle was lower in the ducks fed in cages and nets, respectively, at a low density (P < 0.05). Our findings provide valuable insights into the single and interactive effects of the rearing method and stocking density on duck slaughter performance and proximate composition of meat. The results indicate that a rearing system with a cage pattern and a medium density is better than other arrangements for small-sized meat ducks.