تأثیر سطوح مختلف پودر برگ رزماری (Rosmarinus Officinalis L.) بر عملکرد تولیدی و کیفیت تخم مرغ در مرغان تخمگذار

Abstract

Introduction Supplementation of poultry diets with antioxidant substances seems to be an efficient means for improving the oxidative stability of poultry products. The most important sources of natural antioxidants are plants. The poultry performance parameters generally and positively are affected by the addition of aromatic herbs and their extracts into diets. Rosemary (Rosmarinus officinalis L.), which is herb of the Labiatae family, have been recognized as the plants with the highest antioxidative activity by many authors. The substances associated with the antioxidant activity of rosemary are the phenolic diterpenes, such as carnasol, rosmanol, 7-methylepirosmanol, isorosmanol and carnosic acid. This study examined the effects of dietary supplemented with different levels of dried rosemary leaves on laying hen performance and egg quality in fresh and storage periods. Materials and methods A total of 200 Hy-Line W36 laying hen aged 26 weeks were housed in cages and randomly allocated to 5 treatment groups each containing 40 birds. Each group was divided into 4 replicates. The birds were kept in the laying cages (48.5 cm wide, 45 cm deep, 44 cm high in front and 38 cm high in the rear, 436 cm2 per each one), and housed there along the experimental period. Feed and water were provided ad libitum. The hens received a basal diet (maize and soya bean based; 16.00% crude protein; 2850 kcal/kg ME) that was formulated to meet the hy-line W36 (2014) requirements recommended for nutrients. The diet did not contain any antibiotics and coccidiostats or growth promoters. Treatments were included 0, 0.5, 1, 1.5 and 2 percent of dried rosemary leaves in basal diet. Experiment was designed in a Completely Randomized Design Block with 5 treatments, 4 replicates/ treatment with 10 hens in each replicate, from 29 until 38 weeks of age. Eggs were collected daily and weighed and egg production was calculated on a bird–day basis. Mortality was recorded as it occurred. Feed intake was recorded weekly and calculated as g/hen/d. The value of feed efficiency was calculated as kg feed per kg egg. Twenty four eggs were collected from each group (6 eggs from each replicate) at last 3 day of the experimental period to determine egg quality parameters. Egg quality analyses were done within 24 h of the eggs being collected and after 21d storage period. Egg shell thickness was measured with an egg shell thickness gauge, the egg weight in and out water, the albumen height, the yolk, albumen and shell weight were determined. By using these values, the Haugh units, egg portion (yolk, albumen and shell) relative weight, shell weight per shell unit area and egg specific gravity were calculated. Results and Discussion The results showed dietary supplemented with different levels of dried rosemary have significantly effects on some parameters of performance and egg traits in laying hens (p<0.05). Significant differences in egg production were observed among the groups in the present study. The egg production significantly increased and feed conversion ratio significantly decreased in the birds fed on diets supplemented by 1.5% rosemary dried leaves in comparison to control group, but with increasing levels of dried leaves of rosemary in the diet to 2% the performance indicators decreased. Feed intake was not significantly changed by the dietary treatment.The average weight of the eggs in birds fed a diet containing 1 and 1.5 percent dried rosemary leaves was significantly more than birds fed the control diet. This could lead to better meet the needs of birds because of improved digestibility and utilization of dietary nutrients being consumed. The effect of adding dried rosemary leaves on the egg quality parameters such as Haugh unit, egg specific gravity, shell thickness and shell weight per unit area are not significant. The Hugh unit of eggs, which have been stored for 21 days at 4 C, was higher in birds fed diets containing dried rosemary leaves. Conclusion The highest rate of egg production (%) and egg mass (g/ b/ d) and the lowest feed conversion (g/g) were observed in birds fed diets containing 1.5 % dried rosemary leaves and the highest egg weight, were observed in birds fed diets containing 1 % dried rosemary leaves. Overall addition of dried rosemary leaves in the diet of laying hens lead to improve performance, egg traits and maintaining egg quality during storage.