Lipopolysaccharide (LPS) from gram-negative bacteria was found to be involved in the decrease in laying performance in goose flocks with high stocking density during summer months. LPS injection delayed the increase in the laying rate and altered hierarchical follicle morphology. While there is evidence that LPS exerts suppressive effects on goose reproduction, the time course effects of LPS on the hypothalamus-pituitary-ovary (HPG) axis remain elusive. In this study, we investigated the expression of genes in the HPG axis and the plasma gonadotrophin hormone concentrations in breeding geese at 0, 6, 12, 24, and 36 h after intravenous injection with LPS. The results showed that LPS treatment enhanced and suppressed expression of hypothalamic gonadotropin-inhibiting hormone (GnIH) and gonadotrophin-releasing hormone (GnRH) mRNA, respectively, and similar effects were observed on the mRNA expression of their receptors, GnIHR and GnRHR, in the pituitary. LPS treatment transiently increased follicle FSHβ mRNA expression at 12 h and exerted no significant effect on LHβ mRNA expression in the pituitary. Regardless of the expression of FSHβ and LHβ, plasma follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations were significantly increased during 24–36 h after LPS treatment. In the ovary, StAR and Cyp11a1 were mainly expressed in the granulosa layer (GL) of hierarchical follicles, while Cyp17a1 and Cyp19a1 were mainly expressed in white follicles (WFs) and yellowish follicles (YFs), and to a lesser extent in the theca layer (TL). After LPS treatment, the mRNA levels of Cyp11a1 in the GLs, Cyp17a1 in the WFs and TL, and Cyp19a1 in the WFs, YFs, and TL were significantly decreased. However, LPS treatment transiently upregulated StAR expression at 12 h. These results indicate that the exposure of laying geese to LPS may impair the HPG axis and disturb ovarian steroidogenesis. Our research provides new insights into reproductive dysfunction caused by LPS and the immune challenge in birds.

This study aimed to investigate the effects of different humidity levels on the growth performance, slaughter performance, and meat quality of Pekin ducks through the artificial control of humidity, and to identify the suitable environmental humidity for Pekin duck growth. A completely randomized single-factor design was employed, selecting 144 newly hatched male Pekin ducks with healthy and similar BW (body weight) (60.92 g ± 4.38). These ducks were randomly assigned to four groups (A (RH (relative humidity) = 60%), B (RH = 67%), C (RH = 74%), D (RH = 81%)), with 12 ducks and 3 replicates in each group. The ducks were raised in a climate-controlled room for 42 days with ad libitum access to feed and water. BW and feed intake were measured every 3 days, and slaughter performance and meat quality were assessed at 42 days. There was no significant difference in the ADG (average daily gain) from 1 to 21 days (p > 0.05). The ADFI (average daily feed intake) of Group D was significantly lower than that of Groups A, B, and C (p < 0.05), with no significant differences between Groups A, B, and C (p > 0.05). At 42 days, the BW, ADG, and ADFI of Groups A and C were significantly higher than those of Group D (p < 0.05), with no significant differences among Groups A, B, and C (p > 0.05). Group C had a significantly higher breast muscle weight, breast muscle ratio, liver weight, and liver index than Groups B and D (p < 0.05), with no significant differences between Groups A, B, and D (p > 0.05). The meat shear force in Group C was significantly lower than that in Groups A, B, and D (p < 0.05). The L* (brightness) of Group C was significantly lower than that of Group A (p < 0.05), and the a* (redness) value of Group C was significantly higher than that of Groups A and B (p < 0.05), with no significant difference compared to Group D (p > 0.05). Group B had a significantly higher cooking loss than Groups A, C, and D (p < 0.05), with no significant differences among Groups A, C, and D (p > 0.05). Under 26 °C conditions, Pekin ducks perform best in terms of the production performance and feed efficiency, with high-quality meat, especially when reared at 74% humidity.

The present study investigated the effects of temperature on growth performance, slaughtering traits, meat quality and antioxidant function of Pekin ducks from 21–42 d of age. Single factor analysis of variance was used in this experiment, 144 21 d-old Pekin ducks were randomly allotted to 4 environmentally controlled chambers: T20 (20°C), T23 (23°C), T26 (26°C) and T29 (29°C), with 3 replicates in each group (12 ducks in each replicate), the relative humidity of all groups is 74%. During the 21-day trial period, feed and water were freely available. At 42 d, the BW (body weight) and ADG (average daily gain) of T26 were significantly lower than T20 (p < 0.05), and the T29 was significantly lower than T20 and T23 (p < 0.05). The ADFI (average daily feed intake) of T26 and T29 were significantly lower than T20 and T23 (p < 0.05). Compared to the T29, the T20 showed a significant increase oblique body length and chest width, and both the keel length and thigh muscle weight significantly increased in both the T20 and T23, while the pectoral muscle weight increased significantly in other groups (p < 0.05). The cooking loss of the T29 was the lowest (p < 0.05). The T-AOC (total antioxidant capacity) of T29 was significantly higher than the other groups (p < 0.05), the SOD (superoxide dismutase) in the T29 was significantly higher than the T23 and T26 (p < 0.05). In conditions of 74% relative humidity, the BW and ADFI of Pekin ducks significantly decrease when the environmental temperature exceeds 26°C, and the development of body size and muscle weight follows this pattern. The growth development and serum redox state of Pekin ducks are more ideal and stable at temperatures of 20°C and 23°C.

Lipopolysaccharide (LPS) is one of the important pathogenic substances of E. coli and Salmonella, which causes injury to the reproductive system. Ovarian dysfunction due to Gram-negative bacterial infections is a major cause of reduced reproductive performance in geese. However, the specific molecular mechanisms of LPS-induced impairment of sex steroid hormone synthesis have not been determined. The regulatory mechanism of miRNA has been proposed in many physiological and pathogenic mechanisms. Therefore, the role of miRNA in breeding geese exposed to LPS during the peak laying period was investigated. In this study, twenty Yangzhou geese at peak laying period were injected with LPS for 0 h, 24 h, and 36 h. The follicular granulosa layer was taken for RNA-seq and analyzed for differentially expressed miRNAs. It was observed that LPS changed the appearance of hierarchical follicles. miRNA sequencing analysis was applied, and miR-21 and SMAD2 (SMAD family member 2) were selected from 51 differentially expressed miRNAs through bioinformatics prediction. The results showed that miR-21 down-regulated SMAD2 expression and progesterone (P4) production in LPS-treated goose granulosa cells (GCs). It also determined that overexpression of miR-21 or silence of SMAD2 suppressed the sex steroid biosynthesis pathway by decreasing STAR and CYP11A1 expression. Down-regulation of miR-21 exacerbates the LPS-induced decline in P4 synthesis and vice versa. The findings indicated that miR-21 was involved in LPS regulation of P4 synthesis in goose granulosa cells by down-regulating SMAD2. This study provides theoretical support for the prevention of LPS-induced ovarian dysfunction in geese.

This study aims to investigate the effects of different relative humidity (RH) during 4-21d of Beijing ducks on their condition at 42 d. A total of 48 Pekin duck were randomly allotted into 4 treatments (A:RH60 %, B:RH67 %,C:RH74 %,D:RH81 %), each having 3 replicates of 4 ducks. Different humidity treatments were applied from 4 to 21 days. At 42 d, there were no significant differences (P > 0.05) in body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) among the 4 groups. Oblique body length in D was significantly higher than that in A (P < 0.05). Compared with A, the chest depth of the other groups was significantly increased, and the abdominal fat weight of B and C was significantly increased (p < 0.05). Liver weight and liver index in C and D significantly higher than that in B (p < 0.05). Abdominal fat ratio in B was significantly higher than that in A (P < 0.05). Cholesterol (CHOL) in D was significantly higher than that in A and C (P < 0.05), triglyceride (TG) in C was significantly higher than that in A and B (P < 0.05), and low-density lipoprotein cholesterol (LDL-C) in B was significantly higher than that in A, C, and D (P < 0.05). pH in B was significantly higher than that in A (P < 0.05), brightness (L*) in A was significantly higher than that in B and C (P < 0.05), redness (a*) in B and C was significantly higher than that in A and D (P < 0.05), and yellowness (b*) in C was significantly lower than that in A and D (P < 0.05).The results indicate that the RH of environment during the brooding period has no impact on duck production performance but induces some oxidative stress damage and changes in meat quality. Additionally, ducks subjected to different RH treatments during the brooding period exhibit varying adaptability to the same environment as they mature.

This study aims to elucidate the effects of environmental temperature on growth performance, pectoral muscle fiber structure, fatty acid composition, and gene expression in ducks. A total of 72 ducks at 21-day-old were randomly assigned to controlled environments at temperatures of 20°C (T20) and 29°C (T29) from 21 to 42 days of age. Ducks in the T20 group exhibited significantly higher body weight, body weight gain (BWG), average daily gain (ADG), and average daily feed intake (ADFI) at 42-day-old compared to those in the T29 group (P < 0.05). T20 group showed a marked reduction in muscle fiber diameter and area, with an increase in fiber density compared to those raised at T29 group (P < 0.05). The T20 group also had higher levels of various fatty acids, including saturated (SFAs), monounsaturated (MUFAs), and polyunsaturated (PUFAs) types, while T29 group had lower levels of ω-3 and ω-6 PUFAs and a higher ω-6/ω-3 PUFA (P < 0.05). Transcriptomic analysis revealed 544 differentially expressed genes (DEGs) primarily associated with the Cell Cycle, Cell Replication, and PPAR signaling pathways, with key genes cell division cycle 45 (CDC45), chromatin licensing and DNA replication factor 1 (CDT1), and others identified through protein-protein interaction (PPI) network analysis as crucial for temperature regulation of muscle fiber structure and fatty acid composition, particularly within the significantly enriched cell cycle pathway. These findings were validated by qPCR, confirming consistent gene expression trends. The study highlights how ambient temperature affects muscle fiber characteristics and fatty acid composition in ducks, offering insights into potential strategies for optimizing production conditions to enhance meat quality and efficiency.