No abstract

In this experiment, the effect of hydroalcoholic grape seed extract (GSE) and vitamin C feed supplementation on some blood parameters and heat shock protein 70 (<em>HSP70</em> gene) expression of broiler chickens suffering from chronic heat stress was investigated. Experimental diets included control diet (with no additive), 3 levels of GSE (150, 300, 450 mg/kg), and one level of vitamin C (300 mg/kg). Each diet was fed to 5 replicates of 12 male chicks each, from d 1 to 42. The birds suffered from chronic daily heat stress under 34±1°C temperature with 65 to 70% relative humidity for 5 h from 29 to 42 d of age. Results showed that 300 mg/kg GSE supplementation increased body weight of broilers both before and after heat stress condition (at 28 and 42 d, respectively). Also, birds fed 300 mg GSE/kg diet had higher European production efficiency factor during the whole period of the experiment. Supplementation of GSE decreased the concentration of serum glucose at 28 and 42 d; at 42 d (during heat stress condition) and at 450 mg/kg diet it decreased cholesterol, triglyceride, lowand very low density lipoprotein concentration of serum blood. Vitamin C supplementation decreased serum cholesterol concentration of broilers suffering from heat stress. <em>HSP70</em> gene expression in heart and liver of broilers reduced by GSE and vitamin C supplementation pre- and during chronic heat stress condition.

This study examined the effects of sources and levels of selenium (Se) on performance, carcass parts yield, meat quality and tissue Se concentration in broilers. A total of 960 one-day-old male broilers were divided into 8 treatments in a 4 × 2 factorial arrangement. Chicks were penned in groups of 20 with 6 pens per group. Selenium sources were sodium selenite (SS), Se enriched yeast (SY), DL-selenomethionine (SM) and nano-selenium (NS) and dietary supplemental Se levels were 0.1 and 0.3 mg/kg diet. The average daily gain (ADG), average daily feed intake (ADFI), feed:gain ratio, mortality, and carcass parts yield were not affected by dietary treatments. The level of 0.3 mg/kg Se decreased lightness and increased yellowness of the breast and thighs (P < 0.001). Nano-selenium improved yellowness, redness and meat quality (P < 0.05). The interactive effects of sources and the levels of Se affected Se retention (P < 0.001). Inorganic Se showed poor retention compared to other sources of Se; and NS showed equal retention with the organic sources. With consideration to meat quality responses, NS had a more significant positive effect compared to SS as an inorganic source of Se. Overall, NS and organic sources of Se resulted in better meat quality compared with the inorganic source. Moreover, the highest Se retention percentage was achieved by supplementation of NS followed by organic sources at 0.1 mg/kg compared to SS.

The effect of dietary thyme-oil extract (TOE) supplementation on immune functions of broilers were assessed by feeding graded levels (50, 100, 200, or 400 ppm) of TOE to male broiler chicks during a 42-d feeding trial compared with negative-or positive-control diets. Dietary control treatments included a negative-control diet with no feed-additive supplementation and 2 positive-control groups supplemented with either virginiamycin or zinc bacitracin. In total, 300 1-day-old Ross × Ross male broilers were randomly assigned to 6 dietary treatments that consisted of 5 replicates of 10 birds each. On d 21 and 42, 2 birds from each replicate were killed by cervical cutting to measure the relative weights of spleen and bursa of Fabricius. At 25 d of age, chicks were injected with 0.5 mL of 10% SRBC suspension. Broilers fed with 200 ppm of TOE had heavier weights of bursa of Fabricius than those fed other dietary treatments at d 42 of age. Furthermore, dietary inclusion of 100 ppm of TOE resulted in higher (P < 0.05) total immunoglobulin response in primary antibody titer against sheep erythrocytes compared with other dietary treatments. On the other hand, diet modifications had no significant effect on blood leukocyte subpopulations and heterophil-to-lymphocyte ratio. These results suggest that dietary supplementation with TOE, especially at the level of 100 ppm, can improve immunological responses of broiler chicks.

This study evaluated the effect of dietary calcium (Ca) and available phosphorus (aP) restriction on growth performance, nutrients retention (ATTR), serum metabolites, and tibia in broiler chickens. A total of 720 one-day-old Ross-308 broilers were used in this study. Broilers were fed with 0 (control), 10 (L 1 ), 20 (L 2 ), and 30% (L 3 ) aP-deficient starting (ST) diets during 1-10 days. In ST period, control included 6 and others included 18 replicates of 12 chicks. In post-starter (PST) period, control was still fed with standard diets, while restricted groups were divided into 3 groups and fed with L 1 , L 2 , and L 3 diets. Each PST treatment included 6 replicates of 12 chicks. Data were analysed using a completely randomised design in a 1 (control)þ3 Â 3 factorial arrangement. Factors included aP levels in ST and PST diets. Results showed that L 3 diet decreased feed intake and weight gain but increased ATTR of Ca in starter phase in compare with control group (p<.05). Retarded growth of birds was compensated in post-starter phase. The Ca, P and ALP levels in blood serum were not significantly influenced by aP levels on day 10 and day 42. The ATTR of Ca and tP on day 42, were higher in birds fed L 3 diets than L 2 or L 1 groups (p<.05). The main effect of L 3 group in both ST and PST, decreased (p<.05) tibia ash, Ca, and P in compare with L 1 group. Main effect of post-starter L 3 group had lowest femur breaking strength (p¼.007). In general, restriction in dietary aP increased nutrients ATTR, impaired bone mineralisation and strength without affecting growth performance. HIGHLIGHTSPhosphorus is one of the most important environmental pollutants that is excreted through broilers manure. Birds exposed to aP and Ca restriction increased the retention of these minerals. Dietary aP and Ca restriction impaired bone mineralisation and strength.

The influence of in ovo administration of aromatase inhibitors, clomiphen citrate, tomoxifen, and garlic and tomato extracts on sex differentiation in broiler chickens were investigated in 2 experiments. Five hundred, and 1,000 fertile eggs from Ross 308 strain were used in experiments 1 and 2, respectively. In both experiments, eggs were divided into 5 groups: control group (DW, 0.1 mL/egg), tomoxifen (0.05 mg/egg), clomiphene citrate (0.05 mg/egg), garlic and tomato extracts (0.1 mL/egg). Eggs were sanitized and prepared for incubation in a regular automatic hatchery. Experimental preparations were injected into eggs at day 5 of the incubation period. Injection sites on the eggs were cleaned with 70% ethylic alcohol, bored by a needle, and aromatase inhibitors were injected into the white from the thin end of the eggs by insulin syringe and then sealed by melted paraffin. In experiment 1, hatched one-day-old chicks (mixed-sex) were raised till 42 days of age in 25 floor pens with a completely randomized design. Experiment 2 was designed to investigate the effects of sex and treatments on the feed-to-gain ratio of broiler chicks. In experiment 2, hatched one-day-old chicks were feather sexed and raised till 42 days of age in 50 floor pens. A completely randomized design with a 2 × 5 factorial arrangement of treatments (sex×treatment) was used. Gonads of the chicks were checked to determine their sex on day 42 by optic microscope to make sure feather sexing was correct. At the end of both experiments, on day 42, one bird from each pen was slaughtered for carcass analysis. In experiment 1, hatchability and the one-day-old weight of chicks showed no significant differences among treatments (P > 0.05). However, in ovo administration of garlic and tomato extracts caused the highest percentage of male chicks (P < 0.05). Also, the percentage of thighs and wings of the males were significantly higher than those of females (P < 0.05). In experiment 2, feed-to-gain ratio of male and female broiler chicks showed no significant differences among treatments (P > 0.05).

An experiment was conducted to evaluate the effects of in ovo injection of chrysin, quercetin and ascorbic acid on hatchability, somatic attributes, hepatic antioxidant status and early post-hatch growth performance of broiler chicks. Four hundred and eighty embryonated broiler breeder eggs containing live 18-day-old embryos were divided into six groups of 80 eggs each. One group remained intact and served as a control group (i), whereas the other five groups were injected with the prepared injection solutions as follows: (ii) 0.05 ml distilled water; (iii) 0.05 ml distilled water containing 6 mg ascorbic acid; (iv) 0.05 ml dimethyl sulfoxide (DMSO); (v) 0.05 ml DMSO containing 4.5 mg quercetin; and (vi) 0.05 ml DMSO containing 4.5 mg chrysin. The hatchability rate, hatching weight, residual yolk sac weight, yolk sac-free body weight, liver weight, hepatic glutathione peroxidase and total superoxide dismutase activities, as well as malondialdehyde concentrations, were not affected by the injected solutions. There were no differences between chicks hatched from the control and in ovo injected eggs in weight gain, feed intake and feed conversion ratio from 0 to 11 days of age. However, the specific contrast performed between the in ovo injected groups and intact eggs revealed that in ovo injection significantly increased hatchability rate (p = .0493). This finding also implies that our injection procedure was harmless. In conclusion, the intra-egg injection of chrysin, quercetin or ascorbic acid at the injection rates used in this study did not have a significant effect on hatchability, somatic characteristics, early growth performance and hepatic antioxidant status of broiler chicks. However, the overall hatchability was higher in the in ovo injected eggs as compared to non-injected ones. These findings also confirmed the harmlessness of the procedure developed for in ovo injection in this study.

This study aimed to evaluate the effects of dietary supplemental methionine (Met) source and betaine (Bet) replacement for Met on performance and activity of mitochondrial respiratory chain enzymes (MRCEs) in normal and heat‐stressed broiler chickens. Total of 1,200‐day‐old Ross 308 chicks were allocated to two houses, each consisted of 12 treatments, five replicates of 10 birds each with 2 × 2×3 × 2 (temperature × Met source × Met level × Bet, respectively) split‐plot factorial arrangement. Met level in the basal diets was 70% requirements (Req) that was increased to the requirement or 130% by supplemental dl‐ or l‐Met. Bet was or was not substituted at the rate of 30% supplemental dl‐ or l‐Met. Feed conversion ratio (FCR) in chicks fed 70% l‐Met was lower than those fed 70% dl‐Met diet during 1–10 days (p = 0.04). Broilers fed diets containing requirement or 130% Met, regardless of its source, showed higher weight gain (WG) than those received 70% Met diet during 11–42 days (p < 0.001). Feed intake (FI) of broilers fed 130% Met diet was decreased compared to other two groups during 11–42 days (p < 0.05). One hundred thirty percent Met requirement diet resulted in lower FCR comparing to other two groups during 11–42 days (p < 0.001). Heat‐stressed birds grew less than those under normal condition (p < 0.05). Broilers fed Req Met diet under normal temperature exhibited higher activities of complexes (Cox) I and III (p < 0.05). Cox I activity in heat‐stressed birds fed Bet + diet was similar to those fed Bet‐diet under normal temperature (p = 0.046). It is concluded that performance and the activities of Cox I and III were increased as the level of Met increased. Bet replacement for 30% supplemental Met resulted in similar consequences comparing to non‐Bet replacement diets on performance, but increased the activity of Cox III. l‐Met was effective than dl‐Met at the cellular level. High ambient temperature depressed performance and MRCE activity.