The present study was designed to find the effect of an antibiotic, an organic acid and a probiotic on performance traits, blood biochemical parameters and antioxidant status during the starter phase exposed to Salmonella typhimurium challenge. A total of 300 day-old broiler chicks were randomly allocated to control (basal diet), T1: infected with Salmonella enteric subsp. Typhimurium; T2: infected + avilamycin; T3: infected + organic acid; T4: infected + Bacillus subtilis; T5: infected + organic acid + probiotic. The results showed that body weight, feed conversion ratio and production efficiency factor did not differ (P > .05) between the control and treated groups. Blood albumin and aspartate aminotransferase increased significantly (P < .05) in birds in T5 during the first week. Similarly, total protein and triglyceride concentration increased significantly (P < .05) in T4 and T5. The total antioxidant capacity in the second week decreased significantly in T4 compared to the control. Thiobarbituric acid reactive substances during the first and second weeks did not differ significantly (P > .05) between the control and treated groups. We concluded that the effect of organic acid blend and B. subtilis was similar to that of the antibiotic in broilers during the starter phase exposed to S. typhimurium challenge.

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The current study was performed to investigate the influence of different stocking density rates on the performance, thermophysiological measurements as well as blood parameters of 0 to 30 d of age female Ross broiler. A total of 96 chicks were randomly distributed in a randomized complete block design among 12 cages. Three stocking density rates were applied; low (28.0 kg/m 2 ), medium (37.0 kg/m 2 ) and high (40.0 kg/m 2 ). Results revealed that cumulative body weight gain (BWG) and feed intake (FI) were influenced (P<0.01) by the rate of stocking density, while no effect (P>0.05) were observed for broilers mortalitycorrected feed conversion ratio (FCR). Higher BWG (P<0.01) and FI (P<0.05) were reported for low and medium density rates broilers in comparison to the high density rate broilers. Overall means of body temperature as well as head, neck, wing, body and shank surface temperatures have displayed (P<0.05) higher values in medium and high density rates broilers compared to the low density rate broilers. Furthermore, increasing the stocking density from 28 to 40 kg/m 2 induced a state of hemodilution in higher density rate broilers, which might explain the noticeable decrease in packed cell volume (PCV). Meanwhile, an increase in serum aspartate aminotransferase (AST) was observed in the higher density group, which might indicate hepatocellular injures. It can be concluded that increasing the stocking density rate from 28 to 40 kg of BW/m 2 had evident impingement effects on the performance of broiler chicken and could jeopardize their welfare.

A total 560 day-old broiler chicks (Ross 308) was randomly allocated to seven treatments (eight replicates). Control (basal diet), T1, infected with Clostridium perfringens, T2, infected + Avilamycin at the rate of 0.2 g/kg T3, infected + essential oil of thyme, T4, infected + Sanguinarine, T5, infected + Anti-Salmonella phytobiotic, T6., infected + essential oils of thyme, anise and others (oregano, carvacol, yucca extract and cinnamaldehyde). Feed conversion ratio (FCR) were significantly (P<0.05) high in the T2 during the third week. The dressing percentage decreased significantly (P<0.05) and intestinal weight increased (P<0.05) in T1. Blood protein, and globulin increased significantly (P<0.05) in birds in T6 during fourth weeks, while blood alanine transaminase (ALT) increased significantly (P<0.05) in T5. Thiobarbituric acid reactive substances (TBARS) increased significantly (P<0.05) in T5 and T6. Similarly, villus height and width increased significantly (P<0.05) in T5 and T6. From the results of the present study, it was concluded that different feed additives could be substituted with antibiotics in the feed of broiler exposed to Clostridium perfringens challenge.