Abstract
Probiotic effects on growth performance, carcass traits, blood parameters, cecal microbiota, and immune response of broilers were studied. Two hundred one-day-old male chickens were allocated to one of five treatments (four replicates of 10 birds per treatment): control, and the same control diet supplemented with 0.005%, 0.01%, 0.015% and 0.02% probiotics. Probiotics in feed at 0.01% or higher levels of supplementation improved body weight gain (+12%) and feed conversion rate (-5%) compared with the control. There were no effects on carcass traits, but the relative weights of drumsticks and wings showed increasing and decreasing linear responses, respectively, to probiotic supplementation level. Blood plasma glucose and albumin contents linearly increased (from 167.1 to 200.5 mg dl-1, and from 1.70 to 3.25 g dl-1) with increasing probiotic supplementation. Triglycerides and cholesterol contents were lower in probiotic supplemented treatments (average contents 71.3 and 125.3 mg dl-1 vs. 92.6 and 149.9 mg dl-1 in the control). Probiotics decreased cecal Escherichia coli counts, but had no effects on immunity related organs or immune response. The linear trends, either positive or negative, observed in many of the parameters studied, suggest that more studies are needed to establish the optimal concentration of probiotics in broiler feed.
Highlights
Enteric diseases are an important burden to the poultry industry because of lost productivity, increased mortality, and the associated contamination of poultry products for human consumption (Patterson and Burkholder 2003)
The BWG response to probiotic supplementation level was quadratic (P
In agreement with our results, Anjum et al (2005) and Mehr et al (2007) found that diet supplementation with Protexin at two levels improved BWG and FCR in broilers compared with the control treatment, but both authors observed that the improvements were clearer at the highest level of supplementation
Summary
Enteric diseases are an important burden to the poultry industry because of lost productivity, increased mortality, and the associated contamination of poultry products for human consumption (Patterson and Burkholder 2003). Several papers have shown that probiotics in broiler diets improve the growth performance compared with non-supplemented diets, being as effectives as antibiotic growth promoters (Kalavathy et al 2003, Mountzouris et al 2010, Shim et al 2010). Some authors have investigated the effects of adding a single level of probiotics in broiler diet (Khosravi et al 2010, Mountzouris et al 2007, Zakeri and Kashefi 2011), while others have tested two (Anjum et al 2005, Mehr et al 2007, Nayebpor et al 2007, Panda et al 2006) or three or more levels of probiotic supplementation (Apata 2008, Li et al 2008, Mountzouris et al 2010, Wang and Gu 2010). The aim of the present work was to investigate the effects of increasing levels of probiotic supplementation on growth performance, carcass traits, blood plasma constituents, cecal microbiota and immune response of broiler chickens
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