جستجوی مقالات مرتبط با کلیدواژه « ترئونین » در نشریات گروه « دامپزشکی »

In order to evaluate effects of dietary protein content and threonine to lysine ration on intestinal morphology and mucin secretion, 480 male broiler chicks (Ross 308) were used in a completely randomized design (seven treatments of six replicates) with 2×4 factorial arrangement. Eight dietary treatments were formulated using four threonine to lysine ratio (0.55, 0.6, 0.7, and 0.8) and two standardized ileal digestible protein levels (17 and 18 percent) and fed for 15 to 35 days of age. Sampling was conducted on day 35 with two birds from each replicate. The ratio of 0.8 for threonine to lysine caused an increase in villus height in all parts of the small intestine and villus surface in the ileum, compared to other ratios (P<0.05). Reduction of dietary digestible protein level decreased crypt depth in the duodenum and jejunum (P<0.05). Increasing the threonine to lysine ratio up to 0.7, increased mucin secretion in the jejunum (P<0.05). Decreasing the threonine to lysine ratio to 0.55, increased digesta viscosity in all three parts of the small intestine (P<0.05). The ratio of 0.7 for threonine to lysine caused an increase in serum alkaline phosphatase (ALP). On the other hand, reduction of dietary digestible protein level decreased the serum ALP (P<0.05). Regarding to the results, it seems that the optimum digestible threonine to lysine ratio for wheat-based diets to be around 0.7 to 0.8; and that with reduction in dietary protein level, higher ratios would be of more importance.

Reducing the protein and amino acid content of diet or altering the dietary electrolyte balance were suggested as the effective strategies to prevent the harmful effects of the heat stress in poultry.

This study surveyed the effects of various levels of threonine and dietary cation-anion balance on the broiler chickens under the heat stress conditions.

700 one-day-old male broilers (Ross 308) were used for 6 weeks under high- temperature conditions. This experiment was conducted using a 2 × 3 + 1 factorial experiment based on a completely randomized design, with 7 treatments (5 replicates per treatment and 20 birds per replicate). Experimental factors included two threonine concentrations (recommended level and 10 % above recommended level) and three dietary electrolyte balances (175, 250, and 325 mEq/kg). The control group considered the treatment with a normal threonine concentration (recommended level) and a dietary electrolyte balance of 250 mEq/kg under optimal temperature conditions.

Although there was no interaction between threonine level and electrolyte balance, the electrolyte balance of 175 meq/kg increased the performance index compared to the electrolyte balance of 250 or 325 mEq/kg (P<0.05). The villus height to crypt depth ratio and villus surface area in the jejunum improved with an electrolyte balance of 175 or 250 mEq/kg (P<0.05). A decrease in the dietary electrolyte balance increased in the nitrogen-corrected apparent metabolizable energy (P<0.05). Besides, an increase in the population of lactobacilli and bifidobacteria in the cecum, as well as an increase in protein digestibility, were observed by increasing levels of threonine in the diet (P<0.05).

Based on these results, a high level of threonine or a low electrolyte balance in diet (175 mEq/kg) may improve the performance, metabolizable energy, and intestinal microbial flora of broilers reared under heat stress.

The present experiment was performed to compare the effect of different levels of dietary threonine on performance, carcass characteristics and immune system and blood factors in Japanese quailunder heat stress. For the experiment, 300 one-day-old Japanese quail chicks (Coturnix coturnix japonica) were used in a completely randomized design with six levels of threonine in 6 treatments and 5 replications, each replication containing 10 chicks. The percentages of threonine in the diet of the experimental treatments were: 1) 0.82 %, 2) 0.92 %, 3) 1.02 %, 4) 1.12 %, 5) 1.22 % and 6) 1.32 %. The results showed that the increase in body weight and feed conversion ratio improved significantly in treatments 5 and 6 (p < 0.001). Levels of 1.12 and 1.22% of threonine in the diet had a significant effect on carcass percentage (p < 0.001). There was no significant difference in the weight of lymphatic organs and the titer of antibodies produced against SRBC (sheep red blood cells) in the treatments (p>0.05). Dietary threonine levels had a significant effect on serum uric acid, HDL (high-density lipoprotein) and LDL (low-density lipoprotein) concentrations (p < 0.05). Liver enzyme levels were not significantly different in any of the treatments (p < 0.05). The results showed that increasing threonine in quail diet up to 1.22% can have beneficial effects on performance and improvement of carcass characteristics under heat stress conditions.