Mahmoud M. Azzam

The present study aims to investigate the interaction between the addition of gum arabic as a prebiotic and various stocking densities on performance indicators, intestinal morphology, carcass characteristics, lymphoid organs, and selected blood indices of broiler chickens. A total of 816 1-day-old male broilers (Ross 308) were used and randomly divided into six blocks as replicates with eight treatments per block (forty-eight floor pens) based on 4 × 2 factorial arrangements with four dietary treatments containing 0.00% (CONT), 0.12% gum arabic (T1), 0.25% gum arabic (T2), and 0.10% commercial prebiotic (T3) and two stocking densities (normal = 28 kg/m2; high = 50 kg/m2). All performance indicators were evaluated during the feeding phases. Blood biochemical indicators were analyzed at 36 days of age. At 37 days of age, carcass characteristics, lymphoid organs, and intestinal morphology were measured. On days 1–36, growth performance indicators were negatively affected at high stocking density, but all growth performance indicators except feed intake improved in chickens receiving T1–T3 compared to CONT (p < 0.05). The relative weight of total small intestine and weight-to-length ratio showed a significant interaction between treatments and stocking density (p < 0.05). A high stocking density decreased pre-slaughter weight, carcass weight, and dressing yield, while legs and thymus increased (p < 0.05). None of the interactions or treatments affected carcass characteristics or lymphoid organs (p > 0.05). Indicators of blood biochemistry were not affected by treatments, stocking density, or their interaction (p > 0.05), except for uric acid, creatinine, and aspartate aminotransferase, which were higher at a high stocking density (p < 0.05). In conclusion, gum arabic as a prebiotic improved growth performance, production efficiency, and intestinal morphology in broilers. In contrast, high stocking density negatively affected performance, production efficiency, some blood indices, carcass weight, dressing yield, and intestinal morphology. Further research is needed to determine the mechanism.

Pulicaria jaubertii (PJ) is a medicinal plant used as a synthetic antioxidant and as a traditional medicine due to its bioactive compounds. The objective of this study was to investigate the effects of PJ on carcass traits and breast meat quality parameters of broiler chickens. Two hundred and forty male broilers (1 day old) were divided into four groups (0, 3, 6, and 9 g of PJ/kg of basal diet). Performance indicators were evaluated during the feeding stages, and carcass characteristics and physiochemical and qualitative parameters of breast meat were measured at 36 days old. The results showed that PJ improved performance parameters such as weight gain, feed conversion ratio, and production efficiency index (p < 0.05) in the finishing stage. The diets supplemented with PJ were associated with better carcass characteristics (p < 0.05), but some body parts, such as legs (6 and 9 g PJ) and backs (3–9 g PJ) decreased (p < 0.05). Temperature and initial pH were decreased by PJ (p < 0.05). Meat color was not affected by PJ (p > 0.05), although the yellowness and saturation index were lower at 9 g PJ. Total saturated fatty acid content was higher at 3 g PJ, while total polyunsaturated fatty acids and unsaturated to saturated fatty acid ratio were lower at 3 and 6 g PJ (p < 0.05). Total monounsaturated fatty acid content increased at 6 and 9 g PJ. Omega-6 fatty acids and the ratio of omega-6 to omega-3 were lower at 3 g PJ. PJ resulted in higher weight loss on cooking (6 and 9 g PJ) and shear force (3–9 g PJ). In conclusion, PJ had a positive influence on performance, carcass characteristics, and fatty acid profile, and some meat quality traits were generally improved by PJ, but knowledge of its mode of action is still limited and therefore requires further investigation.