Document Type : Research Paper
Authors
1 Research associate, Animal Science Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO),
2 -Research Professor, Department of Animal and Poultry Nutrition and Physiology, Animal Science Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Abstract
Background and objectives: Considering the limitations of using growth-promoting antibiotics due to the emergence of antibiotic resistance, in recent decades, the usage of plant growth promoters in the livestock and poultry industry has received special attention because of the beneficial effects on growth, immunity and physiological status of animal. It seems that with the aid of new technologies (such as nanoencapsulation) the consumption of plant essential oils in commercial products can be made economical and while improving performance, feed cost can also be reduced. So this experiment was conducted in order to investigate the effects of three commercial plant growth promoters on performance, feed cost per kilogram of live body weight, carcass characteristics and immune responses of broiler chickens.
Methodology: Six hundred day-old Ross 308 broiler chickens (a mixture of two sexes with equal proportion) were used in a completely randomized design with five treatments and four replicates of 30 birds. Experimental treatments included: 1) control diet (no additive), 2) diet containing Virginiamycin (100 g per ton of feed) as a positive control and 3 to 5) diets containing Novi-Herb®, Novi-Grow® and Novi-Herb+® (each was at the rate of 100 grams per ton of feed). Novi-Herb® contained essential oils of thyme (Thymus Vulgaris), ajwain (Trachyspermum ammi), oregano (Origanum vulgare) and nanocapsulated form of chitosan, and Novi-Grow® contained organic acids (lactic acid, formic acid), prebiotics (lactose + yeast cell wall) and some plant compounds included: garlic powder (Allium sativum), turmeric powder (Curcuma longa) and cinnamon powder (Cinnamomum verum). Novi- Herb+® contained essential oils of lemon (Citrus limon) and yeast cell wall as well as other ingredients found in Novi-Herb®. The vaccination program was carried out according to the recommendation of the local veterinarian. Feed intake, body weight, liveability, feed conversion ratio, production index and the cost of feed per kilogram of live body weight were calculated in the period of 1 to 42 days. At the age of 42 days, blood sampling was performed from three birds per replicate in order to differentially count white blood cells and also to evaluate the antibody titer against Newcastle and Influenza vaccine injection. At this age, four birds from each replicate (close to the average weight of the replicate) were killed and after weighing and stuffing, the carcass percentage and the relative weight of the body components (including: breast, thigh, neck and back) and organs (including: liver, heart, gizzard, spleen, bursa of Fabricius, gall bladder, proventriculus) and abdominal fat were calculated.
Results: Dietary addition of evaluated plant growth promoters resulted in a significant improvement in body weight and feed conversion ratio at the age of 42 days compared to the control group (P<0.05). Liveability percentage, European production index and feed cost per kilogram of live weight were not affected by the experimental treatments (P>0.05); however, dietary supplementation of Novi-Herb®, Novi-Grow® and Novi-Herb+®, reduced the cost of feed by 4.8, 4.1 and 2.7 percentage, respectively, in comparison with the control group and by 3.5, 2.8 and 1.4 percentage in comparison with the Virginiamycin group. Among traits such as the relative weight of the carcass, body components and organs, only the relative weight of abdominal fat showed a significant decrease following the dietary inclusion of the evaluated plant growth promoters (P<0.05). Meanwhile, dietary treatments had no significant effect on the percentage of heterophil, lymphocyte, heterophil to lymphocyte ratio and antibody titer in response to the injection of Newcastle and Influenza vaccines (P>0.05).
Conclusion: Based on these results, the evaluated plant growth promoters could be suitable alternatives to antibiotic growth promoter by improving the performance of broiler chickens while numerical reduction of feed cost per kilogram of live body weight.
Keywords
Main Subjects
)