High frequency vaccination-induced immune stress reduces bone strength with the involvement of activated osteoclastogenesis in layer pullets

Effects of Clostridium butyricum on Production Performance and Bone Development of Laying Hens

Probiotics are safe, inexpensive, and effective feed additives, and Clostridium butyricum (CB) has been reported to regulate bone health in addition to having conventional probiotic effects. The bone health of laying hens is closely related to their production performance. Here, we investigated the effects of CB supplementation on the bone health and performance of laying hens. We added CB to the feed of green-shell laying hens, Luhua laying hens, and Hy-line Brown laying hens and examined changes in body weight, feed intake, egg production performance, and egg quality to determine the impact of CB on production performance. The impact of CB on the bones of laying hens was determined by analyzing the bone index, bone bending strength, bone calcium and phosphorus content, and bone mineral density. The study found that CB had little effect on the body weight and feed intake of laying hens. Feed additions of 108 and 109 CFU/kg CB can significantly increase the tibia index and bone mineral density of four-week-old green-shell laying hens. Feed additions of 107 and 108 CFU/kg CB can significantly increase the average egg weight, eggshell weight, and tibia index of 26-week-old Luhua laying hens, but 107 CFU/kg CB will reduce the egg production rate. Adding 108 CFU/kg CB to feed can significantly increase the average egg weight, eggshell weight, and tibia bending strength of 40-week-old Hy-line Brown laying hens. In summary, adding 108 CFU/kg CB is beneficial to the bone and production health of laying hens.

Effects of anti-stress agents on the growth performance and immune function in broiler chickens with vaccination-induced stress

The aim of this study was to evaluate the effects of anti-stress agents on the growth performance and immune function of broilers under immune stress conditions induced by vaccination. A total of 128, 1-day-old Arbor Acres broilers were randomly divided into four groups. Group normal control (NC) was the control group. Group vaccination control (VC), T 0.5%, and T 1% were the treatment groups, which were nasally vaccinated with two doses of the Newcastle disease virus (NDV) vaccine. The chicks in groups T 0.5% and T 1% were fed conventional diets containing 0.5% and 1% anti-stress agents. Thereafter, these broilers were slaughtered on 1, 7, 14, and 21 days post-vaccination. The results indicated that anti-stress agents could significantly reduce serum adrenocorticotropic hormone (ACTH) (P < 0.01) and cortisol (CORT) (P < 0.05) levels, and improve the growth performance (P < 0.05) and immune function of broilers (P < 0.05); However, the levels of malondialdehyde (MDA) (P < 0.05) were decreased, and the decreased total antioxidant capacity (T-AOC) (P < 0.01) levels mediated by vaccination were markedly improved. In addition, anti-stress agents could attenuate apoptosis in spleen lymphocytes (P < 0.01) by upregulating the ratio of Bcl-2 to BAX (P < 0.01) and downregulating the expression of caspase-3 and -9 (P < 0.01), which might be attributed to the inhibition of the enzymatic activities of caspase-3 and -9 (P < 0.05). In conclusion, anti-stress agents may improve growth performance and immune function in broilers under immune-stress conditions.RESEARCH HIGHLIGHTS Investigation of effects and mechanism of immune stress induced by vaccination.Beneficial effect of anti-stress agents on growth performance, immune function, oxidative stress, and regulation of lymphocyte apoptosis.Demonstration of the effects of apoptosis on immune function in the organism.

Clostridium butyricum Can Promote Bone Development by Regulating Lymphocyte Function in Layer Pullets

Bone health problems are a serious threat to laying hens; microbiome-based therapies, which are harmless and inexpensive, may be an effective solution for bone health problems. Here, we examined the impacts of supplementation with Clostridium butyricum (CB) on bone and immune homeostasis in pullets. The results of in vivo experiments showed that feeding the pullets CB was beneficial to the development of the tibia and upregulated the levels of the bone formation marker alkaline phosphatase and the marker gene runt-related transcription factor 2 (RUNX2). For the immune system, CB treatment significantly upregulated IL-10 expression and significantly increased the proportion of T regulatory (Treg) cells in the spleen and peripheral blood lymphocytes. In the in vitro test, adding CB culture supernatant or butyrate to the osteoblast culture system showed no significant effects on osteoblast bone formation, while adding lymphocyte culture supernatant significantly promoted bone formation. In addition, culture supernatants supplemented with treated lymphocytes (pretreated with CB culture supernatants) stimulated higher levels of bone formation. In sum, the addition of CB improved bone health by modulating cytokine expression and the ratio of Treg cells in the immune systems of layer pullets. Additionally, in vitro CB could promote the bone formation of laying hen osteoblasts through the mediation of lymphocytes.

Insulin-like growth factor-1 is involved in the deteriorated performance of aged laying hens

The underlying mechanism behind the deteriorated laying performance of aged laying hens remains unclear. In the present study, the laying performance and gene expression along the hypothalamus-pituitary-gonad axis were determined. A total of 300 healthy 90-wk-old ISA hens with similar body weights were classified into three groups according to their laying rate between 90 and 94 wk of age. The experimental groups were the low laying rate (<60%, LLR), high laying rate (>85%, HLR), and intermediate laying rate (60% < laying rate < 85%, MLR) hens. At the end of 94 wk of age, eight hens were randomly selected from each group for tissue collection. The gene expression of hormones and their receptors were determined in the hypothalamus, pituitary, and follicles. The results showed that the serum 17-β-estradiol had no significant difference among the three groups. However, the level of insulin-like growth factor 1 (IGF1) in LLR hens was significantly decreased in the serum, small white follicles (SWF), and dominant follicles (DF, P < 0.05). Within the hypothalamus and small yellow follicles (SYF), the mRNA expression level of estrogen receptor was higher in the MLR group (P < 0.05). Compared with HLR hens, the steroid hormone-synthesis key gene, CYP19A1 was significantly decreased in the SWF of MLR-hens and DF of MLR- and LLR-hens (P < 0.05). The mRNA expression level of IGF1 receptor was higher in the hypothalamus, pituitary, SWF, large white follicles (LWF), SYF, and DF of LLR hens, compared to the HLR hens (P < 0.05). These results suggest that decreased IGF1 in serum and follicles was associated with the decreased egg production of aged laying hens. The present study provides novel insights into the endocrine changes in aged hens having different egg production.

Adiponectin Reduces Lipid Content in Chicken Myoblasts by Activating AMPK Signaling Pathway

Studies in mammals have shown that adiponectin is secreted mainly by adipocytes, and it plays a crucial role in glucose and lipid metabolism in muscles. Clarifying the crosstalk role of adiponectin between adipose tissue and skeletal muscle tissue is very important for internal homeostasis. The glucose and lipid metabolism of chicken is different from that of mammals, and the role of adiponectin in chickens is unclear. Therefore, it is of great significance to study the effect and mechanism of adiponectin on lipid metabolism in chickens. In this study, the regulating effect of adiponectin on lipid metabolism in chicken myoblasts was explored by adding a certain concentration of exogenous recombinant adiponectin. Results showed that adiponectin reduced intracellular lipid content, increasing the mRNA expression of adiponectin receptor and cellular uptake of glucose and fatty acids. In addition, adiponectin activated the 5' adenosine monophosphate activated protein kinase (AMPK) signaling pathway. The above results suggested that adiponectin reduced intracellular lipid content, mainly by binding to adiponectin receptor, activating AMPK pathway, increasing cellular uptake of glucose and fatty acids, and promoting lipid oxidation.

Dietary Energy and Protein Levels During the Prelay Period on Production Performance, Egg Quality, Expression of Genes in Hypothalamus-Pituitary-Ovary Axis, and Bone Parameters in Aged Laying Hens

Nutrition during the pre-lay period takes effect on the production performance in the laying flock. This study evaluated the effects of dietary energy and protein levels in pre-lay diet on performance during the whole laying period and the egg quality, bone quality, and mRNA expression of hypothalamus-pituitary-gonadal (HPG) axis-related genes of hens at the end of the laying cycle. A total of 1,856 15-wk old Hy-Line brown pullets were randomly assigned to one of the four dietary treatments: using a 2 × 2 factorial arrangement with 2 energy levels (2,700 and 2,800 kcal/kg ME, respectively) and 2 protein levels (15 and 16.5% CP, respectively). Pullets were fed ad libitum from 15 to 20 wk and from 20 wk onward, fed with a similar laying diet till 72 wk of age. At 72 wk, the expression of genes in the hypothalamus, pituitary, ovarian, and follicles and bone quality was evaluated. At 72wk, there were no differences in production performance, BW, organ index, and ovarian parameters among the dietary treatments. High-CP diet increased the egg shape index and eggshell thickness (p < 0.05), but the eggshell breaking strength, Haugh unit, and albumen height did not differ among the treatments. Neither dietary energy nor protein level took an effect of bone quality. Low-energy diet increased the mRNA expression of gonadotropin-releasing hormone-1 (GnRH-1) in the hypothalamus (p < 0.05). The mRNA expression level of estrogen receptor-1 (ESR-1) in the hypothalamus and ovary was elevated by the 2,700 ME-15%CP diet (p < 0.05). The expression of cytochrome family 17 subfamily A polypeptide 1 (CYP17A1) in the large white follicle (LWF), small yellow follicles (SYF) and dominant follicle (DF) was decreased by the 2,800 kcal/kg diet (p < 0.05). These results indicate that the prelay diet had no influence on the production performance but had minimal effect on the eggshell characteristics and bone parameters. These results suggest that the energy and protein level of the prelay diet changes the expression of HPG axis-related genes of hens around the end of the laying cycle without changing the circulating sex hormone profile. The effect of prelay diet on the endocrinal adjustment at the end of the laying cycle needs to be investigated further.

Effect of Immune Stress on Growth Performance and Immune Functions of Livestock: Mechanisms and Prevention

Simple Summary

Immune stress is an important stressor in domestic animals that leads to decreased feed intake, slow growth, and reduced disease resistance of pigs and poultry. Especially in high-density animal feeding conditions, the risk factor of immune stress is extremely high, as they are easily harmed by pathogens, and frequent vaccinations are required to enhance the immunity function of the animals. This review mainly describes the causes, mechanisms of immune stress and its prevention and treatment measures. This provides a theoretical basis for further research and development of safe and efficient prevention and control measures for immune stress in animals.

Abstract

Immune stress markedly affects the immune function and growth performance of livestock, including poultry, resulting in financial loss to farmers. It can lead to decreased feed intake, reduced growth, and intestinal disorders. Studies have shown that pathogen-induced immune stress is mostly related to TLR4-related inflammatory signal pathway activation, excessive inflammatory cytokine release, oxidative stress, hormonal disorders, cell apoptosis, and intestinal microbial disorders. This paper reviews the occurrence of immune stress in livestock, its impact on immune function and growth performance, and strategies for immune stress prevention.

Dusk feeding in laying hens is shifted by light program via involvement of clock genes

Dusk feeding is practised probably to satisfy the energy requirement during night. However, little is known on the changes with clock gene expressions during this feeding behaviour. In our present study, the linkage of clock gene expressions and feeding behaviour in dusk feeding was investigated in laying hens under two lighting programs: the conventional lighting program (Control) with a light period from 05:00 AM to 21:00 PM and a dark period from 21:00 PM to 05:00 AM; or the shifted lighting program group (SLP) with a light period from 02:00 AM to 18:00 PM and a dark period from 18:00 PM to 02:00 AM. The gene expression-related appetite and circadian rhythm were investigated in hypothalamus and proventriculus at 1, 3 and 5 h before scotophase. The results demonstrated that dusk feeding was synchronously shifted with altered lighting program, dusk feeding was observed from 5 h before scotophase in both groups. The expressions of anorexigenic gene proopiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) were downregulated (p < 0.05) during dusk feeding and changed in pace with lighting program. The expressions of clock gene period 2 (Per2) and cryptochrome 1 (Cry1) in hypothalamus were downregulated (p < 0.05) during dusk feeding and shifted by lighting program. In the proventriculus, ghrelin expression was decreased (p < 0.05) during dusk feeding by lighting program. In conclusion, the expressions of clock genes Per2 and Cry1 are linked with the downregulated expressions of anorexigenic genes, POMC and CART, and in turn the augmented feed intake at dusk.

Prolonged scotophase within a 24 hour light regime improves eggshell quality by enhancing calcium deposition in laying hens

Calcium (Ca) and phosphorus (P) transporters are responsible for their absorption and transport in small intestine and kidney, contributing to eggshell formation. The light-dark cycle is a primary cue in the reproduction of laying hen. In this study, we investigated the effect of different light-dark programs on eggshell quality and the expression of genes related to Ca and P transportation in laying hens. Seventy-two 56-week-old laying hens were randomly divided into two groups and reared at 16-h light and 8-h dark (control) or 9-h light and 15-h dark regime (long dark phase, LDP). The expressions of calcium transporter calbindin-D28k (CaBP-D28k), plasma membrane Ca ATPase 1b (PMCA1b), and phosphorus transporter NaPi-IIb (NPt2b) and NaPi-IIa (NPt2a) were measured in the small intestine, kidney, and eggshell gland. The results showed that feed intake (P < 0.001) and egg weight (P = 0.05) were decreased by LDP treatment. Compared with control, the eggshell hardness was increased (P = 0.011) by LDP treatment, but the eggshell thickness and the percentage of eggshell were not changed. The Ca and P contents in eggshell were increased by LDP treatment. During the scotophase, LDP-hens showed higher serum Ca (P = 0.0056) and P levels (P = 0.079) but lower alkaline phosphatase (ALP) activity than that of control hens. In the duodenum, the relative higher expression of CaBP-D28k and PMCA1b in scotophase compared to photophase was masked by LDP treatment. The expression of CaBP-D28k and osteopontin (OPN) in the eggshell gland were increased by LDP treatment, compared to control hens. In the jejunum, the protein expression levels of CaBP-D28k and PMCA1b decreased during photophase in LDP-hens. The result indicates that the increased blood Ca and P concentration during scotophase by LPD treatment is beneficial to the deposition of Ca and P in the eggshell. The result offers an alternative strategy for managing laying hens with poor eggshell quality.

Metabonomic analysis of hypophosphatemic laying fatigue syndrome in laying hens

Laying fatigue syndrome (LFS) is a common disease in poultry, which is characterized by low egg laying rate, increased broken and soft shell egg rate and osteoporosis, and even death of poultry. Insufficient phosphorus content in feed is one of the major causes of LFS. In this study, a total of 22-week-old Roman white shell hens were randomly divided into two groups, including control (group C) and low dietary phosphorus (group P) groups. The hens of groups C and P were fed with a full mixed diet and a mixed diet containing 0.18% available phosphorus content, respectively. At 25, 29 and 34 weeks, the production performance of hens was detected and the serum samples of hens were collected to detect the changes of serum phosphorus, calcium, osteopelectin (OPG), parathyroid hormone (PTH), estradiol (E₂), tartaric acid-resistant phosphatase (TRACP) and alkaline phosphatase (ALP). The keels were removed and x-rayed. In addition, all serum samples were tested by LC-MS metabolomics. Our results showed that low dietary phosphorus decreased the production performance, phosphorus content, and E₂ and OPG levels, while increased calcium and PTH levels, and ALP and TRACP activities in laying hens. The hens of group P had bent keels. Besides, small molecular metabolites in serum were enriched in 10 pathways and 17 metabolites were significantly different according to the area under the receiver operating characteristic curve (AUC) analysis. Our results showed that low phosphorus diet could induce LFS. Also, 17 metabolites detected by metabonomics can be used as biomarkers for clinical diagnosis and early warning of hypophosphatemic laying fatigue syndrome (HLFS). This study provides a scientific basis for the early prevention and treatment of HLFS.