Nutritional impact of inclusion of garlic (Allium sativum) and/or onion (Allium cepa L.) powder in laying hens’ diets on their performance, egg quality, and some blood constituents

Background Many studies mentioned that using medicinal herbs and plants as feed additives to ruminants seems to be a recent trend depending on the availability and their cost but using them with monogastric animals and birds, as pharmaceutical tool, is available. As an example, the importance of garlic or onion in recent years, thanks to a wide range of useful properties, has been increasingly used as an additive in nutrition and protection of farm animals. Their action was manifested in a reduced expanding range of pathogenic microorganisms in the digestive tract, which resulted in the rapid growth of poultry, efficient digestion, and increased immunity and health of poultry. Methods One hundred and eight 30-week-old laying hens were randomly divided into six dietary treatment groups {G 1 control, G 2 contained 0.5% garlic powder (GP), G 3 contained 1% GP, G 4 contained 1% onion powder (OP), G 5 contained 1% OP + 0.5% GP, and G 6 contained 1% OP + 1% GP}. Each group included 18 hens in six replicates (3 birds/each). So, this work carried out to investigate the impact of incorporating garlic powder (GP) and/or onion powder (OP) in laying hens’ diets on their performance, egg quality, and some blood constituents. Results Incorporating GP, OP, and the mixture of them in laying hen diets had no significant effect on the average egg weight and consumption/hen/day throughout the three stages of egg collection, but had a significant improvement in the number of eggs/hen, percentage of egg production, egg mass/hen, and feed conversion. Inclusion of GP, OP, or the mixture of them in laying hen diets had no significant effect on the shape index, Haugh unit, albumin, and shell percentages; also, an insignificant increase for shell thickness was observed, but egg weight increases ( P