ABSTRACT The hypothalamic-pituitary-gonadal (HPG) axis is a key neuroen-docrine regulation system involved in the growth and reproduction of poultry. High-temperature conditions lead to the physiological dysfunction of target organs of the HPG axis of poultry, ultimately affecting the animals’ growth and development. In this study, we evaluated the effect of heat stress (HS) on the development of cells secreting major reproductive hormones of the HPG axis (i.e., hypothalamus, pituitary gland, ovary, and testis) of Wenchang chicks. Seventy-two one-day-old healthy Wenchang chicks were randomly divided into control (CK) and HS groups. The HS group was placed in a 40 ± 0.5°C artificial climate chamber for heat-stress treatment from 13:00 to 15:00 daily for six consecutive weeks. As development progressed, compared with the CK group, the gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels in the hypothalamus and testosterone (T) levers in the testes of male chicks in the HS group were significantly decreased at three weeks of age (p<0.05). However, GnRH levels in the hypothalamus and estradiol (E2) levels in the ovaries of female chicks in the HS group were variable and significantly lower than those of the CK group at four and five weeks of age (p<0.05). In addition, the LH and FSH levels in the pituitary gland were significantly lower than those in the CK group at two and four weeks of age and at four and six weeks of age, respectively (p<0.05). In brief, HS caused dysfunction of the corresponding target organs of the HPG axis in Wenchang chicks, and this affected the normal growth and development of the cells’ HPG axis.

ABSTRACT This study conducted an in-depth investigation on the development of GABAergic neurons and their receptors in HPG axis-related target organs of Wenchang chicks under heat stress. One-day-old healthy Wenchang chicks were randomly divided into control (CK) and heat stress (HS) groups. Chicks in the HS group were placed in a 40±0.5°C climatic chamber for HS treatment from 13:00 to 15:00 daily. By immunohistochemistry and Western blotting, GABA and GABAA receptor (GABAAR) expression in the hypothalamus of the HS group was significantly higher (p<0.05), but GABAB receptor (GABABR) expression was significantly lower than that of the CK group (p<0.05). Expression of GABA and its two receptors in the pituitary tissues of the HS group was significantly lower than in the CK group (p<0.05). Expression of GABA and GABABR in ovaries in the HS group was significantly higher, but expression of GABAAR in the testes of the HS group was lower than that of the CK group (p<0.05). In the male chicks, expression of GABA and its two receptors in the hypothalamus, pituitary, and testicular tissues of the HS group was significantly higher than that of the CK group (p<0.05). Western blotting showed that the GABAAR and GABABR expression of the HS group was significantly higher than that of the CK group at 3 and 5 weeks of age. Thus, HS caused GABAergic nervous system disorder in the HPG axis of Wenchang chicks and seriously hindered the normal development of GABAergic neurons in chicks, leading to the disorder of the expression of GABA and its receptors in tissues.

ABSTRACT This study aimed at investigating the effects of broccoli residues fermented with probiotics (BF) on the growth performance, immunity, and gut health in broilers challenged with Clostridium perfringens (C. perfringens). A total of 600 broilers (one day old) were randomly allotted into five treatments with six replicates of 20 birds each and were reared until 42 days of age. The treatments included a positive control (PC, fed a basal diet and reared on uncontaminated litter), a negative control (NC, birds reared on litter contaminated with C. perfringens and fed a basal diet), and NC plus BF at 25, 50 or 75 g/kg of diet. The BF contained yeast 3.1 × 107cfu/g, lactic acid bacteria 9.5 × 106cfu/g and Bacillus subtilis 3.5 × 106cfu/g. Birds in the NC group showed lower (p<0.05) feed intake and body weight gain, whereas BF supplementation recovered (p<0.05) the growth performance to the levels of PC group. Dietary BF at 50and 75 g/kg reduced (p<0.05) broiler mortality. Similarly, compared to the NC group, BF increased (p<0.05) immune organ weights and serum immunoglobulins A, G, and M to the levels of PC group. The ileal populations of Escherichia coli and Gram-negative bacteria were decreased (p<0.05) by BF to the levels of PC, and C. perfringens was also decreased (p<0.05) by BF. The serum profiles of mono- and di-amine oxidase were decreased (p<0.05) by BF. BF at 75 g/kg reduced (p<0.05) monoamine oxidase compared with the other BF doses. The results suggest that broccoli residues fermented with probiotics can be a novel biological feed additive to protect the performance and health of broilers against C. perfringens infection.

ABSTRACT The VLDLR gene plays important roles in the growth and adiposity in humans and mice. The purpose of this study was to investigate the relationship between VLDLR gene genetic polymorphisms and growth and abdominal fat traits of the Gaoyou domestic duck. A total of 267 Gaoyou ducks were employed for testing. A 18bp deletion was identified in VLDLR signal peptide coding region. The results of c2 test suggested that the genotype frequencies of VLDLR signal peptide coding region were not in Hardy-Weinberg equilibrium. Least squares analysis showed that body weight (BW) of -18bp/-18bp genotype ducks was significantly higher than those of other genotypes from six (BW6) (p<0.05) to ten weeks of age (BW10) (p<0.01). The association analysis was performed taken body weight as covariant for abdominal percentage (AFP). Results showed that there was not interaction between genotype (p>0.05) and body weight for AFP and different genotypes had a significant effect on AFP (p<0.05). The results of Bonferroni t-test revealed that the abdominal fat percentage (AFP) of -18bp/-18bp genotype was significantly lower than those of +18bp/-18bp (p<0.05). Preliminary studies have shown that VLDLR may be a candidate gene for the selection for growth and abdominal fat, and the results of the present study indicate that VLDLR strongly influences carcass abdominal fat content of Gaoyou ducks.

ABSTRACT Under routine feeding conditions, 1-day-old male chicks were randomly divided into control group (CK), heat-stress group (HS), and GABA + heat stress group (GABA+HS). The thymus contents of IL-1, IL-2, TGF-β1, IFN-γ, GH and HSP70 were determined by enzyme-linked immunosorbent assays. The results showed that: (1) IL-1 and TGF-β1 contents of HS group were significantly lower than those of the CK group (p<0.05), and those of the GABA+HS group were significantly higher relative to the HS group (p<0.05); (2) IL-2 and IFN-γ contents of the HS group were significantly higher than those of the CK group (p<0.05), and those of the GABA+HS group were significantly lower relative to the HS group (p<0.05);(3) the thymus GH content of all three groups first increased and then decreased. The expression levels GH of the HS and GABA+HS groups were significantly lower than CK group (p<0.05); and (4) HSP70 expression levels in the thymus were significantly higher in the HS and GABA+HS groups relative to the CK group (p<0.05). These results indicate that heat stress affected thymus development, immune functions, and overall growth of chickens. Furthermore, it was shown that feeding GABA may significantly improve the immune responses of heat-stressed chickens by increasing the expression levels of IL-1 and TGF-β1, and effectively alleviate the negative effects of heat stress on thymus development by changing HSP70 expression and GH secretion.

ABSTRACT We investigated the effect of heat stress (HS) on the expression of the GABA receptor in the hypothalamic-pituitary-gonadal (HPG) axis of Wenchang chickens. Real-time quantitative RT-PCR (qRT-PCR) was used to quantify the GABA receptor mRNA levels along the HPG axis of chickens under HS (40±0.5 °C) for 1-6 weeks. Our results showed that the expression of GABAA and GABAB receptor at the mRNAs levels in the tissues of HPG axis exhibited fluctuation and variability. After HS, the mRNA level of GABAA receptor was significantly reduced in the hypothalamus of 1-week-old and in the pituitary of 3-week-old chickens, but significantly increased in the pituitary of 1-, 4-, and 5-week-old chickens. The GABAB receptor mRNA level significantly declined in the hypothalamus of 1-week-old and in the pituitary of 3-week-old chickens, but was significantly upregulated in the pituitary and testis of 1- and 2-week-old chickens. At other time points, the expressions of GABAA receptor and GABAB receptor showed no significant differences compared with control group. These results indicated that the levels of GABAA receptor and GABAB receptor mRNAs varied in different tissues of the HPG axis in chickens of different ages, displaying temporal and spatial variations. GABA receptor behaved as a positively-regulated gene by HS, i.e., its mRNA was increased by HS; similarly, it was a negatively-regulated gene by HS, when its expression was reduced by HS.

This paper examines phosphorus forms following application of organic fertilizer. Dynamic changes in the phosphorus fraction content were simulated by the waterlogged incubation method. This study was carried out using comparison tests between sterilized and non-sterilized treatments to analyze the effect of organic fertilizer on phosphorus form transformation. The experimental results showed that fertilization of paddy soil could significantly increase the content of the phosphorus fraction (p<0.05). Furthermore, the organic phosphorus content increased during incubation. The levels of organic phosphorus in the non-sterilized treatments were higher than in the sterilized treatments. However, the variation of the inorganic phosphorus content was contradictory. A significant correlation (r=-0.484, p<0.01) was observed between O-P and highly resistant organic phosphorus, as well as among Al-P, Ca-P, moderately labile organic phosphorus and moderately resistant organic phosphorus. Therefore, it is concluded that applying organic fertilizer can increase the content of the phosphorus fractions of paddy soil. With microorganisms present, Al-P and Ca-P can be transformed into moderately labile organic phosphorus and moderately resistant organic phosphorus, and O-P can be transformed into highly resistant organic phosphorus.