Dietary calcium and non-phytate phosphorus levels affect the performance, serum biochemical indices, and lipid metabolism in growing pullets.

This experiment aimed to study the effects of dietary calcium (Ca) and non-phytate phosphorus (NPP) levels on performance, serum biochemical indices, and lipid metabolism in Beijing You Chicken (BYC), a local chicken. A 3 × 3 factorial design was adopted, dietary Ca levels were 0.66, 0.71, and 0.76%, NPP levels were 0.25, 0.30, and 0.35%. A total of 648 ten-wk-old BYC growing pullets were randomly divided into 9 groups with 6 replicates per group, and 12 birds per replicate. Growth performance, serum biochemical indices, and lipid metabolism indicators from 10 to 16 wk were measured. The results showed as follows: 1) Dietary Ca and NPP alone did not affect growth performance, but the interaction of dietary Ca and NPP affected average feed intake (AFI) of growing pullets (P < 0.05). The AFI was the lowest for the group with 0.71% Ca and 0.25% NPP (3,550.0 g, P = 0.036). 2) Dietary Ca level significantly affected serum P content (P < 0.05); dietary NPP had an influence trend on serum Ca content (P= 0.054). Dietary NPP levels and the interaction of Ca and NPP significantly affected alkaline phosphatase (AKP) activity. 3) Dietary Ca levels significantly affected TC content and HDL-C content (P < 0.05). Dietary NPP level significantly affected TG content (P < 0.05), the TG content in 0.25% and 0.30% NPP groups was significantly lower than that in 0.35% NPP group (P < 0.05). The interaction of dietary Ca and NPP significantly affected TG, TC and HDL-C contents (P < 0.05). TG, TC, and LDL-C levels were lower and HDL-C levels were the highest in the group with 0.66% Ca and 0.25% NPP. In summary, appropriate dietary Ca level can regulate serum TG, TC, and HDL-C content. Dietary Ca and NPP levels can be adjusted in pullet phase to avoid excessive obesity during the egg-laying period. This study recommended that dietary 0.66% Ca and 0.25% NPP benefit for the lipid metabolism of BYC growing pullets without affecting the performance.

Vitamin E supplementation alleviates the oxidative stress induced by dexamethasone treatment and improves meat quality in broiler chickens.

In the present study, the effects of long-term exogenous glucocorticoids administration and dietary supplementation of alpha-tocopheryl acetate on the induction of lipid peroxidation in skeletal muscle were investigated. Male broiler chicks were randomly assigned to 2 diet treatments: the basal diet supplemented with 20 (low level of vitamin E) or 200 (high level of vitamin E) mg of vitamin E (as DL-alpha-tocopheryl acetate)/kg of diet. At 35 d of age, the chickens in each dietary treatment were randomly divided into 3 groups of 30 chickens and subjected to the following treatments: daily s.c. injection of dexamethasone (DEX, 2 mg/kg of BW) for 6 d, sham injection of saline (control), or the sham-treated pair-fed control that maintained the same feed intake as DEX treatment (pair-control). The results showed that the growth of chickens was suppressed by DEX, whereas it was improved by the high level of vitamin E treatment. The DEX treatment resulted in augmented plasma concentrations of TBA reacting substances. Muscle TBA reacting substances levels were higher in DEX chickens at both 24- and 48-h time points postslaughter. Vitamin E supplementation suppressed the formation of lipid peroxidation in both plasma and skeletal muscle tissues. Muscle activity of superoxide dismutase was significantly increased by DEX treatment in both musculus pectoralis major and musculus biceps femoris and maintained as such during the initial 48 h postmortem. The result of the present study indicated that DEX treatment increased the saturation level of skeletal muscle fatty acids. These results suggest that vitamin E supplementation was favorable for the performance of broiler chickens by alleviating the oxidative stress induced by DEX treatment.

Effects of L-arginine supplementation on glucose and nitric oxide (NO) levels and activity of NO synthase in corticosterone-challenged broiler chickens (Gallus gallus).

In the present study, three experiments were conducted to investigate the effect of oral supplementation of l-arginine (ARG) on the disposal of glucose in stressed-broiler chickens (Gallus gallus domesticus). In all the three experiments, the broiler chickens were randomly subjected to one of the four treatments at the beginning of the experiments: oral administration of saline, glucose (2.0g/kg body weight, BW), l-arginine (0.5g/kg BW) or mixed solution (2.0g glucose+0.5g arginine/kg BW). Immediately after the oral treatment, the experimental chickens were subcutaneously injected with corn oil (Experiment 1), corticosterone (CORT, 4mg/kg BW, Experiment 2) or insulin (1U/kg BW, Experiment 3), respectively. Blood samples were obtained at the beginning (0-h), 0.5-, 1- and 2-h time points after injection and the levels of plasma glucose, urate, nitric oxide (NO) and activity of NO synthase (NOS) were measured. The results showed that plasma NO levels and NOS activity were significantly suppressed while glucose and insulin concentrations were increased by CORT treatment. In contrast, insulin administration improved the circulating level of NO and activity of NOS. ARG supplementation could not improve the circulating levels of NO and NOS activity in CORT-challenged chickens and, in turn, the glucose disposal. The result suggests that NO is involved in insulin-mediated glucose transport in chickens, as well as that in mammals. The reduced circulating level of NO resulted from the suppressed activity of NOS rather than the reduced substrate concentration.

Corticosterone administration and dietary glucose supplementation enhance fat accumulation in broiler chickens.

1. The effects of exogenous corticosterone administration and glucose supplementation on energy intake, lipid metabolism and fat deposition of broiler chickens were investigated. 2. A total of 144 three-d-old male chickens were randomly assigned to one of the following 4 treatments for 7 d: a low energy diet (10.9 MJ ME/kg, 200 g/kg CP) with or without corticosterone (30 mg/kg diet) and drinking water supplemented with glucose (80 g/l) or saccharine (2 g/l, control). 3. Body weight (BW) gain and breast and thigh muscle yields (% body mass) were all significantly decreased by corticosterone treatment. The relative cumulative feed intake (RCFI) and relative ME intake (RMEI), rather than the feed (FI) or ME intake (MEI) were increased by corticosterone administration. Both feed efficiency (FE) and caloric efficiency (CE) were decreased by corticosterone administration. Corticosterone administration had no obvious effect on water consumption. 4. Glucose supplementation had no influence on BW gain and breast and thigh muscle yield (as % of body mass). FI or RCFI was decreased while MEI or RMEI was increased by glucose supplementation. FE was improved by glucose treatment, whereas CE was reduced. 5. Liver weight and abdominal, cervical and thigh fat deposits were all significantly increased by either corticosterone or glucose treatment. 6. Plasma concentrations of glucose, urate, triglyceride, non-esterified fatty acids (NEFA), very low density lipoprotein and insulin were all significantly increased by corticosterone treatment. Glucose supplementation had no obvious influence on any of the measured plasma parameters except for NEFA, which were significantly increased. 7. Lipoprotein lipase activities in either cervical or abdominal adipose tissues, rather than in thigh fat tissue, were significantly elevated by either glucose or corticosterone treatment.