Introduction
Threonine is one of the essential amino acids in broiler nutrition, which plays an important role in improving growth performance, feeding efficiency and strengthening the immune system. This amino acid is especially important in the synthesis of proteins, the production of enzymes and the strengthening of the intestinal mucosal barrier. Deficiency or excess of this amino acid can have negative effects on the health and productivity of poultry. The aim of this study is to investigate the effect of different levels of threonine on growth performance and safety indicators of broiler chickens.
Materials and methods :
To investigate the effect of different levels of threonine, an experiment was designed using 300 pieces of one-day-old male broiler chickens from Ross 308 breed. The treatments included five different levels of threonine (0.85%, 0.95%, 1.05%, 1.15%, and 1.25%) added to the basal diet. Basal ration was adjusted according to NRC (1994) standard nutritional requirements. Chickens were kept in the same environmental and management conditions, and the experimental period included two stages of growth (first 21 days) and final (next 21 days).
During the experimental period, growth parameters including live weight, feed consumption and feed conversion ratio were recorded. Also, immune indices including antibody titer against Newcastle disease and bird flu and phagocytosis activity were measured. Data analysis was performed using SAS software and Duncan's test to compare means.
Results and discussion :
The results showed that the optimal level of threonine (1.05%) provided the best growth performance and improved food conversion ratio. Chickens that received this level of threonine had higher live weight and more optimal feed intake. Also, this level caused a significant increase in the antibody titer against Newcastle disease and bird flu, which indicated the strengthening of the immune system.
Lower levels of threonine (0.85% and 0.95%) led to decreased live weight and increased feed conversion ratio. This was probably due to the insufficiency of this amino acid to meet the metabolic and immune needs of chickens. On the other hand, levels higher than the optimal level (1.15% and 1.25%) led to a decrease in feeding efficiency and an increase in production cost. This result may be due to the negative effects of excess threonine on the balance of amino acids in the body of birds.
conclusion
Adequate threonine levels in broiler diets can improve growth performance and immune responses. It is suggested that the level of 1.05% threonine is considered as the best level for economic productivity and health of birds. Further studies are recommended to investigate the long-term effects of threonine on gut health and meat quality.
References:
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2. Kidd, M. T., Kerr, B. J., & Anthony, N. B. (2001). “Dietary threonine for broilers: dietary interactions and feed additive considerations.” Poultry Science, 80(6), 691-701.
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4. NRC (1994). “Nutrient Requirements of Poultry.” 9th Revised Edition. National Academy Press, Washington, D.C.
5. Emadi, M., & Kaveh, K. (2009). “The role of threonine in broiler nutrition and its effect on growth performance and immune response.” World’s Poultry Science Journal, 65(4), 689-703
