L-carnitine is a nutritional supplement having fat-burning property and plays an important role in lipid metabolism, energy release, and also improve the production yield, immunity and blood constitute. This paper reviews the effects of L-carnitine on quantitative and qualitative characteristics of broilers. According to the reviewed literature, the application of L-carnitine (50-200 mg/kg) has no significant effect on the growth performance, however, using L-carnitine as much as 300-800 mg/kg resulted to an improvement in the body weight (2226.00-2575.00 g) compared to the control chicks (1998.40-2338.75 g). The feed conversion ratios of the chickens fed the same amount of L-carnitine were 1.66-1.86 kg/kg, which was improved in comparison with the control chicks (1.87-2.09 kg/kg). Abdominal fat of the broiler chickens fed 50-900 mg/kg L-carnitine was 0.98-1.75%, which is lower than the control chicks (1.79-2.16%). For immunity, the antibody titers against the Newcastle virus in the chickens fed 250 mg/kg L-carnitine was between 4.6- 5.5 which is more than control chicks (4.3-5.2). The antibody titer against the influenza virus in the chickens fed the same amount of L-carnitine was between 5.6-6.3, which was more than the control chicks (4.3-5.8). The use of 100-600 mg/kg L-carnitine could reduce triglyceride (90-104.4 mg/dL) compared to the control chicks (125-104.7 mg/dL) and also reduced the cholesterol (109-115 mg/dL) compared to the control chicks (129.25-131 mg/dL). The application of 100-600 mg/kg L-carnitine also could reduce low-density lipoprotein (LDL) from 19.1-72.2 mg/dL to 16.5-49.0 mg/dL. However, the application of 100-900 mg/kg L-carnitine had no significant effect on the sensory characteristics of broiler chicken meat. In general, it can be concluded that L-carnitine can be used as a dietary supplement on the health of broiler chickens without any negative effect on growth performance.

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The objective of the study was to ascertain the effects of the litter type and its chemical supplementation on rectum characteristics in broilers. Experiment was conducted based on a 3×3 factorial arrangement with 3 litter treatments (sand, wood shaving, and paper) and 3 chemical reagent treatments (no reagent, lime, and bentonite). From obtained results, it is showed that litter type had not significant effect on rectum weight, relative weight of rectum, rectum length, rectum width, and rectum diameter (P>0.05), although sand litter had the highest rectum weight, relative weight of rectum, and rectum width numerically. Chemical regent type also had not significant on rectum weight, relative weight of rectum, rectum length, rectum width, and rectum diameter (P>0.05), however no reagent resulted to the highest rectum weight, relative weight of rectum, rectum length, and rectum diameter numerically. Meanwhile statistical differences between nine studied treatments for weight of rectum were significant (P≤0.05) and the highest level of rectum weight belonged to treatment 1 (sand as litter and no reagent), and treatment 3 (sand as litter and lime as reagent) remained at lower level than other treatments.

Sericulture has been an important agricultural industry since 2650 BC (Seidavi et al. 2006). There are about 10 million farmers and 0.5 million related industrial workers in the world. The present capacity of silkworm eggs production in Iran is about 70000 boxes per year which are distributed among 40000 silkworm house holders. Annual cocoon production in Iran is about 6000 metric tons which is small in comparison with production in previous centuries. Silkworm breeding using selection systems can improve line and hybrid performance. Individual selection based on cocoon weight in GGP generation (great grandparent) improved GP (grandparent) and P (parent) parental line generation (Seidavi et al. 2007), but it did not consider the effects on resistance performance of hybrid generation. In this experiment, the effects of two phenotypic selections of GGP parents on vitality (percentage of survival pupae) and resistance properties in six of their hybrids (including 31×32, 32×31, 103×104, 104×103, 107×110 and 110×107) were studied.