Effect of exogenous bile salts supplementation on the performance and hepatic lipid metabolism of aged laying hens

Bile acids (BA), a series of hydroxylated steroids secreted by the liver, are involved in the digestion and absorption of dietary fats. In the present study, the effect of exogenous BAs on the performance and liver lipid metabolism of laying hens was investigated. Three hundred and sixty 50-wk-old Hy-line Brown hens were randomly allocated into three groups and subjected to one of the following treatments: fed with the basal diet (control, Con), the basal diet supplemented with 0.1 g/kg (0.1 g/kg BAs), or 0.2 g/kg (0.2 g/kg BAs) porcine BAs. Laying performance, egg quality, and blood parameters were measured during the 8-wk experimental period. The expression of genes related to hepatic lipid metabolism was determined at the end of experiment. The results showed that BAs treatments had no influence (P > 0.05) on laying rate, egg weight, and feed efficiency. BAs treatment, however, significantly decreased mortality of hens (P = 0.006). BAs treatment showed a transient negative influence on eggshell quality at week 4 but not at week 8. The yolk color on week 8 was increased by BAs treatments (P < 0.0001) compared to control. The duodenum index showed a tendency to be increased (P = 0.053) and jejunum index were increased (P = 0.007) by BAs treatment. Compared to control, BAs treatments decreased lipid droplet content (P < 0.0001) and TG content (P = 0.002) of liver. Fatty acid synthase activity was also decreased as an effect of BAs dietary supplementation. Compared to the control group, 0.1 g/kg BAs treatment increased (P < 0.05) the mRNA expression of genes Farnesoid X receptor (FXR) (P = 0.042), cytochrome P450 family 7 subfamily A member 1 (CYP7A1) (P = 0.002), and cytochrome P450 family 8 subfamily B member 1 (CYP8B1) (P = 0.017), fatty acid synthase (FAS) (P = 0.020), acetyl-CoA carboxylase (ACC) (P = 0.032), sterol regulatory element binding protein-1c (SREBP-1c) (P = 0.037), proliferator-activated receptor gamma (PPARγ) (P = 0.002), apolipoprotein B (APO-B) (P = 0.020), and very low density lipoprotein receptor (VLDLR) (P = 0.024). In conclusion, the addition of exogenous BAs reduces lipid accumulation in liver. BA supplementation reduces the mortality of hens and improves egg yolk color, with no unfavorable effect on laying performance. The result suggests that suppressed FAS activity is involved in the reduced hepatic lipid accumulation by BAs treatment.

Effects of Dietary Energy Level on Performance, Plasma Parameters, and Central AMPK Levels in Stressed Broilers

This study aimed to characterize the effects of diets with different energy levels on the growth performance, plasma parameters, and central AMPK signaling pathway in broilers under dexamethasone (DEX)-induced stress. A total of 216 1-day-old male broiler chickens were allocated to groups fed with high (HED), National Research Council-recommended (control), or low (LED) energy diets. At 10 days old, chickens were treated with or without dexamethasone (DEX, 2 mg/kg body weight) for 3 consecutive days. HED increased broiler average daily gain (ADG) at 10 days old, compared with the LED (P < 0.05), while average daily feed intake (ADFI) and feed conversion rate (FCR) decreased as the dietary energy level increased (P < 0.05). Chickens fed a HED had higher total protein (TP) content, albumin (ALB), glucose (GLU), total cholesterol (TCHO), high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol, compared with the control group (P < 0.05). At 13 days old, DEX decreased ADG and increased FCR in broilers fed with different energy diets (P < 0.05). The DEX-HED group had a higher ADFI than non-DEX treated HED group chickens. In addition, TP, ALB, triglycerides (TG), TCHO, HDL, and LDL content levels in the DEX group were higher than those in the control group (P < 0.05). The uric acid (UA) content of the LED group was higher than that of the HED group (P < 0.05). Further, gene expression levels of liver kinase B1, AMP-activated protein kinase α1, neuropeptide Y, and GC receptor in the hypothalamus were increased in chickens treated with DEX (P < 0.05). There was a trend toward interaction between plasma TCHO and hypothalamic LKB1 expression (0.05 < P < 0.1). In conclusion, this study suggests that HED improves growth performance, plasma glucose and total cholesterol at 10 days old broilers, but had no significant effect on performance, plasma parameters, and central AMPK in stressed broilers.

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.

Effects of zinc oxide nanoparticles on regulatory appetite and heat stress protein genes in broiler chickens subjected to heat stress

This study was conducted to explore the effect of the zinc oxide nanoparticles (ZnONPs) supplement on the regulatory appetite and heat stress (HS) genes in broiler chickens raised under high or normal ambient temperatures. In this study, 240 one-day-old male broiler chicks (Cobb 500) were randomly assigned to 48 battery cages. From day 1, these 48 cages were randomly subjected to four different treatment strategies: Control (wherein, their basal diet included 60 mg/kg of ZnO), ZNONPs 40 (wherein basal diet included 40 mg/kg of ZnONPs), ZnONPs 60 (basal diet included 60 mg/kg of ZnONPs), and ZnONPs 100 (basal diet included 100 mg/kg of ZnONPs). Thereafter, from day 22 to 42, the chickens from each dietary treatment group were subjected to different temperature stresses either normal (23 ± 1 °C constant) or HS (34 ± 1 °C for 6 h/d), which divided them into eight different treatment groups. Our findings revealed that dietary ZnONPs altered the gene expression of cholecystokinin (ileum), heat stress proteins (HSP) 70 (jejunum and ileum), and HSP 90 (duodenum, jejunum, and ileum). The gene expression of ghrelin was affected by the interaction between the ZnONPs concentration and temperature in the duodenum and stomach. More studies are required to elucidate its complex physiological and biochemical functions of the regulation of gene expression within the intestine in heat-stressed broiler chickens.

Propionate inhibits fat deposition via affecting feed intake and modulating gut microbiota in broilers

As one of the 3 main short-chain fatty acids, the role of propionate in chicken fat metabolism is largely unknown. In this study, we demonstrated that dietary supplementation of coated sodium propionate (SP) moderately inhibits fat deposition in broiler chickens, as evidenced by the decreased adipocyte mean area (P < 0.01), the lowered triglyceride content in abdominal fat tissue (P < 0.01), and the reduced transcription of several lipogenic genes in liver and abdominal fat tissues (P < 0.05). Surprisingly, the propionate content was not significantly elevated either in serum or in the cecal chyme by SP administration (P > 0.05). However, SP application significantly decreased the average daily feed intake of broilers (P < 0.05). In addition, the composition of the cecal microbial communities was altered, with the ratio of Firmicutes to Bacteroidetes decreasing in particular (P < 0.05). At the genus level, SP application increased the richness of Alistipes, Lactobacillus, and Bifidobacterium, while reduced the abundance of Lachnospiraceae and Helicobacter significantly (P < 0.05). Moreover, in vitro experiments indicated that, although physiological concentrations of propionate (0.01 to 0.1 mmol) upregulated or downregulated the transcription of some fat synthesis-associated genes (P < 0.05), they did not significantly affect the triglyceride accumulation in hepatocytes and adipocytes (P > 0.05). These results suggest that feed supplementation with SP inhibits fat deposition in broilers by reducing feed and caloric intake, but not via direct regulation on hepatic fat synthesis or adipocytic fat deposition. Alteration in the relative populations of the gut microflora suggests that SP may have gut health implications.

5-Hydroxytryptophan Suppresses the Abdominal Fat Deposit and Is Beneficial to the Intestinal Immune Function in Broilers

Background

Serotonin (5-HT), a monoaminergic neurotransmitter, involves in the regulation of many physiological functions. In the present study, the effects of 5-hydroxytryptophan (5-HTP), the precursor of 5-HT, on lipid metabolism and intestinal immune function in broiler chickens were investigated in chickens.

Methods

Two hundred broilers were divided randomly into two groups and fed separately with a corn-soybean basal diet (CD) or the basal diet supplemented with 0.2% 5-HTP.

Results

The results showed that 5-HTP reduced (P < 0.05) feed intake and the abdominal fat pad weight. 5-HTP treatment tended to upregulate the mRNA level of adiponectin receptor 1 (ADP1R) and ADP2R in abdominal fat but had no significant influence on their protein levels (P > 0.05). In 5-HTP-chickens, lipopolysaccharide exposure decreased secretory immunoglobulin A (sIgA) concentrations in serum and the duodenal contents. Expression of mRNA encoding interleukin (IL), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β) decreased after 5-HTP treatment; however, LPS increased expression significantly in 5-HTP-treated chickens compared with CD chickens. In 5-HTP-chickens, the phosphorylation of mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) were reduced, but the phosphorylation of ribosomal p70S6 kinase (p70S6K) was increased in the duodenum.

Conclusion

In summary, the result suggests that dietary 5-HTP supplementation reduces accumulation of abdominal fat and is beneficial to intestinal immune function.