| چکیده انگلیسی مقاله |
Background and objectives: Considering the limitations on the use of growth-promoting antibiotics due to the emergence of antibiotic resistance, the use of plant-based growth promoters in the livestock and poultry industries has garnered significant attention in recent decades. These alternatives are recognized for their beneficial effects on animal growth, immune function, and physiological status. It appears that with new technologies such as nanoencapsulation, the application of plant essential oils in commercial products can become more cost-effective while enhancing performance and reducing feed costs. Therefore, this experiment investigated the effects of three commercial plant growth promoters on performance, feeding cost per kilogram of live body weight, carcass characteristics, and immune responses in broiler chickens.
Methodology: randomized design comprising five treatments with four replicates of 30 birds each. The experimental treatments were as follows: 1) a control diet (no additive), 2) a 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 at 100 grams per ton of feed). Novi-Herb® included essential oils from thyme (Thymus vulgaris), ajwain (Trachyspermum ammi), and oregano (Origanum vulgare), along with a nanocapsulated form of chitosan. Novi-Grow® contained organic acids (lactic and formic acid), prebiotics (lactose and yeast cell wall), and plant-based compounds such as garlic powder (Allium sativum), turmeric powder (Curcuma longa), and cinnamon powder (Cinnamomum verum). Novi-Herb+® combines essential oils of lemon (Citrus limon) and yeast cell wall with other ingredients found in Novi-Herb®. Recommendations from the local veterinarian implemented the vaccination program. Data was collected on feed intake, body weight, livability, feed conversion ratio, production index, and feeding cost per kilogram of live body weight from day 1 to 42. On day 42, blood samples were taken from three birds per replicate to perform differential white blood cell counts and evaluate antibody titers against Newcastle and Influenza vaccines. Additionally, four birds per replicate, selected based on average body weight, were slaughtered. After weighing and stuffing, carcass yield and the relative weights of body components (breast, thigh, neck, back) and internal organs (liver, heart, gizzard, spleen, bursa of Fabricius, gall bladder, and proventriculus), as well as abdominal fat, were measured.
Results: Including the evaluated plant growth promoters in the diet significantly improved body weight and feed conversion ratio at 42 days of age compared to the control group (P < 0.05). There were no significant effects of the treatments on livability, the European production index, or feed cost per kilogram of live body weight (P > 0.05). However, the use of Novi-Herb®, Novi-Grow®, and Novi-Herb+® led to cost reductions of 4.8%, 4.1%, and 2.7%, respectively, compared to the control group, and 3.5%, 2.8%, and 1.4%, respectively, compared to the Virginiamycin group. Among the measured traits, only the relative weight of abdominal fat showed a significant decrease with the inclusion of the plant-based growth promoters (P < 0.05). Dietary treatments did not significantly affect the percentage of heterophils, lymphocytes, the heterophil-to-lymphocyte ratio, or antibody titers in response to Newcastle and Influenza vaccine injections (P > 0.05).
Conclusion: Based on the results, the evaluated plant growth promoters can serve as effective alternatives to antibiotic growth promoters by improving broiler performance and numerically reducing feed cost per kilogram of live body weight. |