Improving productive and reproductive performance of dual-purpose crossbred hens in the tropics by lecithin supplementation

In order to study the influence of lecithin and vegetable oils on improving productive and reproductive performance, egg quality, and metabolic profile of dual-purpose crossbred hens in the tropics, a total of 224 hens, 47-wk old, 112 each of Gimmizah and Silver Montazah strains were fed seven isonitrogenous diets. Experimental treatments consisted of feeding seven different diets to layers; four isocaloric diets containing either no added lipid (control), 3% vegetable oil mixture, 3% soy lecithin or 6% soy lecithin; and three high-energy level diets, containing an extra 3% vegetable oil mixture, 3% or 6% soy lecithin added to the control diet. Thus, the experimental design was factorial, consisting of seven lipid treatments by two strains of hens. Results indicate that 3% lecithin as an extra ME source, or feeding 11.72 MJ ME/kg diet containing the same level of lecithin, improved productive and reproductive performance of crossbred hens. Moreover, lecithin at 6% as an extra ME supplement significantly increased yolk percentage and improved Haugh unit score and yolk color, while increasing EE digestibility and plasma total lipids. Hen strain had a significant effect only on digestibility of OM, percentage liver and Haugh unit score, with the Gimmizah strain having higher values.     

Pathogenicity of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> and <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> against <Emphasis Type="Italic">Galleria mellonella</Emphasis>

The greater wax moth Galleria mellonella L. (Lepidoptera: Pyralidae) is occasionally found in beehives and is a major pest of stored wax. Entomopathogenic fungi have recently received attention as possible biocontrol elements for certain insect pests. In this study, 90 isolates of Beauveria bassiana and 15 isolates of Metarhizium anisopliae were screened for proteases and lipases production. The results showed significant variations in the enzymatic action between the isolates. In the bioassay, the selected isolates evinced high virulence against the 4th instar of the G. mellonella larvae. The isolates BbaAUMC3076, BbaAUMC3263 and ManAUMC3085 realized 100% mortality at concentrations of 5.5 × 10⁶ conidia ml⁻¹, 5.86 × 10⁵ conidia ml⁻¹, and 4.8 × 10⁶ conidia ml⁻¹, respectively. Strong enzymatic activities in vitro did not necessarily indicate high virulence against the tested insect pest. The cuticle of the infected larvae became dark and black-spotted, indicating direct attack of fungus on the defense system of the insects. The LC₅₀ values were 1.43 × 10³, 1.04 × 10⁵ and 5.06 × 10⁴ for Bba3263AUMC, Bba3076AUMC and Man3085AUMC, respectively, and their slopes were determined by computerized probit analysis program as 0.738 ± 0.008, 0.635 ± 0.007 and 1.120 ± 0.024, respectively.