Influence of Feeding Frequency and Dietary Fiber Sources on Gene Expression of Lipogenesis Enzymes in Liver of Broiler Breeder Hens

This trail was conducted to determine the effects of quantitative and qualitative feed restriction on performance, plasma hormone and metabolites levels, fat metabolism and lipogenesis in Cobb ٥٠٠ broiler breeder females from ٢٤ to ٣٨ wk of age. Breeder pullets and cockerels were reared on skip-a-day feeding until ٢٠ wk, weighed and transferred to breeder house and distributed in experimental pens based on body weight. All birds were photostimulated at ٢٢ wk. A flock of ١٩٢ Cobb ٥٠٠ breeder pullets were divided in two different experiments. In First experiment, effect of increasing feeding frequency on lipogenesis was evaluated. Feeding treatments includes once, twice and thrice a day feeding with ٤ replicates. The total amount of feed allowance per day was the same. In once-a-day group, all birds received their total feed at ٠٦١٥ a.m. whereas in twice-a-day group, feeding program was ٥٠% at ٠٦١٥ a.m. and the other ٥٠% at ١٢٣٠ p.m. In thrice-a-day group, daily feed allowance was divided in ٣ equal parts and feeding program was ٣٣% at ٠٦١٥ a.m., ٣٣% at ١٢٣٠ p.m. and last ٣٣% at ١٨٣٠ p.m. The purpose of second study was to determine the effects of insoluble (Cellulose and wheat bran) and soluble fiber inclusion (pectin and cotton seed meal), differing in physico-chemical properties, on lipoid metabolism in broiler breeder hens during laying period. Dietary treatments were as follows: Treatment ١(Control), control diet based on corn and soybean meal with AME content of ٢٧٥٠ kcal/kg; Treatment ٢ (CSM), where nutrient density of control diet was decreased ١٠% by inclusion of ١٠٠g/kg cotton seed meal, Treatment ٣ (PEC), where the control diet was diluted with pectin in the ratio of ٥:١٠٠ (w/w); Treatment ٤ (CEL), where the control diet was diluted with cellulose in the ratio of ١٠:١٠٠ (w/w) and Treatment ٥ (WB), where nutrient density of control diet was decreased ١٠% by inclusion of ٢٠٤ g/kg wheat bran. All experimental groups received an equal AME and other nutrients per day. The expression of certain regulatory genes in fat metabolism [malic enzyme (ME); fatty acid synthase (FAS); acetyl coenzyme A carboxylase (ACC); ATP citrate lyase (ACL) and steroyl CoA desaturase ١ (SCD١)] were determined by Real-Time PCR procedure. Results of the first study indicated that twice and thrice-a-day feeding increased the hen-house and henday egg production compared to control group (P٠.٠٥). Allocating the feed on two and three times per ٤٢ day caused increases in egg weight (P٠.٠١) and little increase in yolk weight. Hepatic expression of ME, FAS, ACC and ACL genes relative to β-actin in both two and three times fed breeders in peak of production significantly decreased (P٠.٠٥), but there is no significant difference between hepatic lipogenic enzymes expression in plateau phase of production cycle (٣٨ wk). In the second study, the hens fed insoluble fiber-diets (cellulose and wheat bran) produced ٦.٢٥ eggs more than those fed control diet over the entire experimental period (P≤٠.٠١). There was no difference among production rate of hens consumed soluble fiber-diets (cotton seed meal and pectin) compared to control diet. Egg weight in celloluse-fed birds significantly elevated (P≤٠.٠٥). Hepatic expression of ME, ACC and ACL genes relative to β-actin in fiber fed breeders in peak of production significantly decreased (P٠.٠٥), however, dietary fiber sources did not influenced their hepatic gene expression in plateau phase of production. Hepatic expression of SCD١ didnot influences the dietary treatments in both trials. Also, enzyme activity of MAE was reflective of gene expression in the liver. Results of the present study demonstrate a role of reducing hunger and frustration in changing fat metabolism, as well as, effect of increasing feeding frequency and reducing fasting period in improving reproductive performance of broiler breeder hens. In summery, the feeding regimens greatly affected hepatic gene expression in broiler breeder females.