Document Type : Research Paper
Authors
1 MsC graduate student of Poultry Nutrition, Department of Animal Science, Faculty of Agriculture. Ilam University, Ilam-Iran
2 Department of Animal Science, Faculty of Agriculture, Ilam University, Ilam, Iran
3 Department of Animal Science, Khorasan Razavi Agricultural and Natural Resources Research and Education Center, AREEO, Mashhad, Iran
Abstract
Recently, the inclusion of phytogenic feed additives in poultry for the purpose of supplementing gut health and positively impacting performance has received a great deal of attention and concern. Thyme is used in poultry nutrition in the form of herbal feed additive as it is known that its contents, such as thymol and carvacrol, have a positive impact on broiler performance and feed utilization, which in turn results in enhanced economic profits. This improvement in performance can be attributed to activation of the digestive system structure and function which causes an enhanced absorption and metabolism of the nutrient supplement and its ability to alter the gut microbiota. Formulating diets based on ideal protein concept aim to reduce total N-excretions and ammonia emissionswhile meeting the nutritional needs of the animals. Poultry needs a specific quantity and balance of essential amino acids and nitrogen (for synthesis non-essential amino acids, NEAA) rather than crude protein. Chickens fed the standard levels of dietary protein can synthesize NEAA from excess essential amino acids. However, when low-protein diets are used, less EAA is available for NEAA synthesis. Reducing dietary protein in broiler feed is not a new subject. However, it is revealed that only few trials covered an entire production cycle with several feeding phases while majority of experiments focused on one phase only. Thyme improve protein afficiency so in this experiment, the effect two levels of Zataria multifolra (0 and 0.5 %) and two protein levels (100 (CP100) and 95 (CP95) % of Ross-308 broiler chickens’ requirement) on growth performance, physiological responses and meat quality were studied. In a completely randomized design with 2×2 factorial arrangement, 280 Ross-308 broiler chickens (one-d-old, mixed sexes) were allocated to 4 treatments, 5 replicates and 14 birds in each replicate. Growth performance, immune response, blood metabolites, blood cell count, meat quality and jejunum morphometry were considered. Feed intake, BW and FCR of finisher and total period of production, carcass parameters except abdominal fat percentage were not affected by thyme poweder, protein levels or their interaction (P > 0.05) while inclusion of thyme powder on CP100 diet improved BW and BWG of broiler chickens during starter and grower periods (P < 0.05). Inclusion of thyme powder on CP95 diet decreased serum cholesterol and LDL-cholesterol and increased HDL concentration. Feeding CP95 diet contatining 0.5 thyme poweder led to increase total protein concentration and decreased liver enzymes activity (P < 0.05). Also, feeding CP95 diet containing thyme powder decreased heterophile but increased lymphocyte count (P < 0.05). Dietary treatments had no significant effects on humoral immune response, relative weight of lymphoid organs, breast and thigh meat pH and color, and jejunum morphometry (P > 0.05). In conclusion, apart from addition of thyme powder, 5 percent protein dilution in this experiment had no negative effects on growth performance, immune response and meat quality of broiler chickens and it maybe suggestible for broiler chickens.
Keywords
)