This experiment was conducted to determine the effects of citric acid (CA) on carcass characteristics and physico-chemical attributes of male Venda chickens. A total of 200 male, one-day-old Venda chicks were distributed in a completely randomized design with four treatments and five replicates of 10 chickens each. The treatments were as follows: four diets with citric acid supplementation of 0, 12.5, 25, and 50g CA/kg. In this study, the live weight, carcass weight, thigh weight, drumstick weight, and carcass yield were higher in CA25 than in other treatments. The wing weight was higher in CA12.5 than in CA0. The highest value was determined in CA0, followed by CA12.5, and CA25, respectively, according to pH24 h, pH48 h, pH72 h, cooking loss, as well as shear force. The lowest value was recorded in CA50 as expected. The pH24 h, pH48 h, pH72 h, cooking loss, and shear force were found to be similar. The current study indicates that 12.5 and 50 g CA/kg can be used easily in the diet of male Venda chickens without any negative effects.

ABSTRACT The growth differentiation factor 9 (GDF9) gene plays a vital role in the growth and maturation of ovarian follicles in laying hens. However, its messenger ribonucleic acid (mRNA) expression levels in preovulatory ovarian follicles of indigenous chickens remain poorly understood. The study aimed to identify the association between egg weight and egg quality traits, ovarian follicles morphology, and mRNA expression levels of the GDF9 gene in pre-ovulatory ovarian follicles of the South African Potchefstroom Koekoek chicken breed. The correlation results showed that egg weight (EW) had a positively high significant correlation (p<0.01) with egg width (EWD), yolk weight (YW), shell surface area (SSA), albumen weight (AW), albumen ratio (AR) and egg volume (EV), and a positive significant correlation (p<0.05) with egg length (EL). The Student’s T-test results revealed that the numbers of large yellow follicles were significantly lower (p<0.05) than those of small yellow follicles. ANOVA findings showed that there was a significant difference (p<0.05) in the average weight of the large yellow follicles. The quantitative Reverse Transcription Polymerase Chain Reaction (RT-qPCR) findings indicated that there were significant differences (p<0.05) in the mRNA expression levels of the GDF9 gene in preovulatory ovarian follicles of the Potchefstroom Koekoek chicken breed. The mRNA expression was more abundant in F1 and F4 than in other ovarian follicles.