ABSTRACT
Background: Heat stress declines the performance through physiologic changes of the poultry
Objectives: This experiment was conducted to evaluate the effects of different levels of L-carnitine on performance, carcass characteristics and some blood parameters of broiler chickens fed with high fat diets under heat stress
Methods: Two hundred one-day-old broiler chicks [Ross 308] were used in a completely randomized design by four treatments and five replicates [pen] 10 birds in each replicate. The chickens of experimental treatments were fed with basal diet [control group] and the diets plus the different levels of 100, 200 and 300 mg/kg L-carnitine. The experimental diets were used during the finisher period [day 24 to 42 of age] and under heat stress [32 +/- 1°C as cyclic from 9.00 AM to 5.00 PM]
Results: The results showed that the chicks fed with the highest L-carnitine had the higher weight gain during the finisher period as compared to control and the lower L-carnitine fed chicks [p<0.05]. Furthermore, the feed conversion ratio of birds fed with the medium and high L-carnitine levels [100 and 300 mg] was lower than that of control birds [p<0.05]. In orthogonal contrasts, L-carnitine supplementation caused the improvement in weight gain and feed conversion ratio during both the finisher and whole experimental periods [p<0.05]. The consumption of highest L-carnitine decreased the abdominal fat as compared to control [p<0.05]. In orthogonal contrasts, L-carnitine consumption caused the higher glucose and lower abdominal fat in comparison to control [p<0.05]
Conclusions: Totally, the results of recent experiment show that consumption of 300 mg/kg L-carnitine improves the performance of broiler chickens through the increase in dietary fatty acids and energy
ABSTRACT
The effects of probiotic and calcium butyrate [Ca-butyrate] as feed additives on performance and immune response have been shown in laying hens. The aim of the present study was to investigate the effects of different levels of probiotic and Ca-butyrate on performance, egg quality, blood parameters and immune response in laying hens. Two hundred and eighty eight Hy-Line W-36 hens [62 to 70 wks of age] were used in a 2×3 factorial arrangement with three levels of probiotic [0, 0.07 and 0.01 percent] and two levels of Ca-butyrate [0 and 0.1 percent] in a completely randomized design of 6 treatments and 8 replicates. The results showed that feed intake, feed conversion ratio, egg production, shape index, yolk index, haugh unit, egg weight and specific gravity were not affected by probiotic and Ca-butyrate. While egg weight and egg mass were significantly [p<0.05] increased using probiotic compared with the control diet, such an effect was not observed due to Ca-butyrate addition. However, shell thickness showed significant increase [p<0.05] in response to Ca-butyrate. The interaction between different levels of probiotic and Ca-butyrate was only significant for feed conversion ratio [p<0.05]. Antibody titer against sheep red blood cell [SRBC] was not affected [p>0.05] by experimental treatments. The concentration of serum albumin was significantly increased [p<0.05] by adding probiotic and Ca-butyrate to feed. Furthermore, significant increase [p<0.05] in total serum protein was pronounced in response to probiotic and Ca-butyrate. However, other serum metabolites [total calcium, triglycerides and cholesterol concentrations] were not affected by treatments. The relative percentage of heterophiles and heterophiles to lymphocytes ratio were significantly decreased [p<0.05] using probiotic. Dietary probiotic and Ca-butyrate can be considered as additives to improve immune responses in laying hens