Heat stress is one of the major problems of poultry in heat areas of the world including Iran, especially in summer, leading to reduced performance, the production, feed intake, growth rates and effective use of the feed (Sahin ., 2009). In general, birds have a thermal comfort zone, which ranges between 18 to 22 ° C and no problem for the physiological regulation of body temperature in this range will. Birds lack sweat glands, increase in body temperature above the point of the thermal comfort zone, leading to problems with the excretion of excess heat due to metabolic heat production and ultimately to reduce the nutrient metabolic, to reduce the feed intake of that this practice leads to loss of yield and growth rate of the (Geraert , 1996). Research shows that between different levels of temperature and stability of the bird, a negative correlation there. So that put the chicken in the temperature range 32 ° C compared with normal temperature, a 14% decrease in food intake (El Husseiny, 1981). Heat stress, minerals and vitamins are excreted from the body increases, so that the concentrations of vitamins A, E, C and the minerals iron, magnesium, zinc and chromium in serum and liver is reduced (Feenster, 1985; Kucuk, 2003).
The effects of heat stress in poultry by increasing the temperature from 30 ° C to above appear (Yardibi, 2008). The temperature range 32.2 to 43 ° C in a short time, resulting in decreased levels of antibodies, blood cells and plasma, as well as a 14 percent reduction in food intake in chickens is (Aengwanich, 2008). Research shows that heat stress, the production of egg laying hens and feed intake of broilers can be greatly affected by the (Kucuk, 2003). Heat stress of laying hens on egg shell thickness will lead to weight loss (Wolfenson, 2001). Broilers at high temperature range, leading to lower quality and carcass characteristics and increase the time it gets to market (McDougald, 1980). Heat stress also causes undesirable meat and carcass characteristics of growing period becomes (Sandercock, 2001). In Conditions of heat stress, broiler feed intake by about 3.6 percent for every 1 ° C increase in temperature (22 to 33 ° C) reduced (Furlan, 2004). Indicate that the heat stresses in the range of 32 ° C decrease in food intake by 14 percent at the age of 4 weeks and 24% at 6 weeks of age is (Belay, 1996). Studies Belay and Teeter (1996) found that temperature range 24 to 35 ° C reduced the rate of phosphorus, potassium, sodium, magnesium, sulfur, manganese, copper and zinc in broiler chickens compared with the 24 ° C temperature range. Energy intake of the nutrient limiting the performance of birds at high temperatures.
With the increase in ambient temperature above 21 ° C, the energy required to maintain approximately 30 kcal per day reduced (Daghir, 2008). It is reported that the upper temperature limit stop resulted in the digestibility of nutrients. It is observed that the digestibility of foods such as protein, starch and fat in broilers under heat stress significantly reduced. The enzyme activity of trypsin, Chymotrypsin and amylase significantly decreased in the temperature range of 32 ° C is (Hai, 2000). Glutamine (Gln) is a non-essential amino acid which is quantitatively the most abundant free amino acid in blood plasma compared to other free amino acids (Tapiero, 2002; Newsholme, 2003 a; Murakami , 2007; Bartell and Batal2007). Gln is important for different physiological functions and maintenance of cell functions (Newsholme, 2003a; Tapiero, 2002). It acts as the substrate for several aminotransferases involved in the synthesis of purines, glucosamine, pyrimidine's and asparagine (Watford, 2008; Li, 2007). Gln is also involved in protein, peptide, and n nucleic acid synthesis. It is available as source of oxidative energy and in the biosynthesis of glucose, amino sugars and glutathione (Tapiero, 2002; Newsholme, 2003 a). Objective of the recent study was to assess the effect dietary glutamine supplementation on performance, some blood parameter, characteristics carcass and quality meat of broiler chickens under continuous heat stress condition.
Materials and methods
A total of two hundred one-day-old broiler chicks (Ross 308) were obtained from a commercial hatchery. Chickens were weighed and allotted into 5 groups randomly. Each treatment comprised 5 replicate pens with 10 birds each. All chickens had ad lib access to water and feed and the diets were available as mash from. Diets were based on corn-wheat- soybean meal and formulated to meet the chicken’s recommended levels of Ross requirements (Ross Company). Diets had similar nutritive value (Table 1). The chickens were fed the same starter (from day 1 to day 21of age) and grower (from day 22 to day 42 of age) diets throughout the whole experiment but received different levels of 0.0, 0.25, 0.5, and 1 percent glutamine. Chicks were raised at 32±1 °C for inducing heat stress from day one to the end of the experimental period (day 42 of age). Birds were exposed to 23h and 1h darkness during the experiment. Body weight gains (BWG), feed intake (FI) and feed conversion ratio (FCR) were determined for the starter, grower and whole the experimental periods.
To evaluate carcass traits at 42 days of each replications based on the weighted average number of chicks a selection unit, weighing, sampling and were slaughtered. Two blood samples in tubes containing anticoagulant Ethylenediaminetetraacetic acid (EDTA) were obtained. Blood plasma was separated by centrifugation for 5 min at 5,000 rounds and laboratory measurements were stored at -20 ° C. The first set of blood samples for measurement of total cholesterol, triglycerides and total protein were used. Full blood samples for measuring the activity of hemoglobin concentration were taken. Plasma samples were then transported to the laboratory and cholesterol, triglyceride and total protein samples with a spectrophotometer (Alcyon300, USA) and Test Kits Pars (Tehran, Iran) were measured. Hemoglobin concentration was measured by the colorimetric method. This test method is thus indicative of hemoglobin with drobkins (containing potassium Ferricyanide) reaction and its derivatives are often placed into cyan. Cyan absorption spectrophotometer at 540 nm was recorded and compared with standard hemoglobin concentration is measured in grams per deciliter of blood.
For measuring carcass weight, liver, breast, thigh, heart, and abdominal fat were measured and weighed each of these organs to body weight ratio was calculated. Quality parameters and characteristics of meat, thigh and breast muscle samples were zippers and inside pockets, and after Slaughtering the freezer (-20 ° C) were relocated. Digital PH meter to determine the pH of meat (calibrated with buffers 4 and 9) were used. Malondialdehyde(MDA), a secondary product of lipid oxidation compounds that largely defines the oxidative spoilage. One way is fast, simple and MDA common calculation method is TBA1. This method is based on the adsorption of a molecule if the reaction of MDA with two molecules of TBA is based (Botsoglou .,2004). Ash, dry matter, fat, protein, meat color, respectively, Through ash famous furnace ash, oven 60 ° C, Soxhlet, Kjeldahl and apparatus (Minolta chronometer (CR-100 in terms of three factors A, B and L) were measured. The data were analyzed based on a completely randomized design using the GLM procedure of SAS (SAS Institute, 2003). Duncan’s multiple range tests was used to separate the means when treatment means were significant (P≤ 0.05). The experimental protocols were reviewed and approved by the Animal Care Committee of the Urmia University.
Table 1. Ingredient composition and chemical analysis of the experimental diets (g kg –1, as fresh matter)
Results and discussion
Dietary supplementation effects of Gln on BWG, FI, and FCR during the starter, grower, and whole experimental periods are shown in Table 2. No Gln effect was detected for FI and FCR during the starter, grower, or whole experimental periods (P > 0.05). Similarly, no significant difference was determined between the treatments for BWG during the starter period (P > 0.05). During the grower period and the whole period, BWG was affected by Gln (P < 0.05). The BWG of MG-fed birds was greater than that of other birds during the grower period (P < 0.05), but there was no significant differences between other treatments. For the whole experiment, the BWG of MG fed birds was higher than that of ZG- and LG-fed birds (P < 0.05). No significant difference was noted between HG birds and other treatments for BWG during the whole period (P > 0.05).
Table 2. The effects of L-glutamine on performance of broiler chickens reared under heat stress conditions during the starter (0 to 21 day of age), grower (22 to 42 days of age), and whole experimental (0 to 42 days of age) periods.
The effect of different levels of glutamine the weight of internal organs is shown in Table3. No significant differences between treatments for breast weight, thigh, liver, heart, abdominal fat was observed at 42 days of age (P > 0.05). Glutamine consumption in independent comparisons significant effect on various parameters of the internal organs of the body weight was (P > 0.05).
Table 3. The effects of L-glutamine on Carcass characteristics of broiler chickens reared under heat stress conditions during the whole experimental (0 to 42 days of age) periods
As shown in Table 4, the consumption of glutamine had no effect on cholesterol levels, triglycerides, total protein, hemoglobin was 42 days (P > 0.05). In addition, independent comparisons of glutamine supplementation had no significant effect on various parameters of blood parameters (P > 0.05).
Table 4. The effects of L-glutamine on Blood Parameter of broiler chickens reared under heat stress conditions whole experimental (0 to 42 days of age) periods .
As shown in Table 5, the consumption of glutamine had no effect on characteristics was 42 days (P > 0.05). In addition, independent comparisons of glutamine supplementation had no significant effect on various parameters of Quality Meat (P > 0.05).
Table 5. The effects of L-glutamine on characteristics and Quality Meat of broiler chickens reared under heat stress conditions during the whole experimental (0 to 42 days of age) periods
In general results of a recent investigation showed that 0.5 percent glutamine without affecting other performance parameters has resulted in improved weight gain. Agrees with recent experimental results, consume 5 grams of glutamine separately or in combination with 100 mg of gamma-aminobutyric acid improves weight gain in broilers 21 to 42 days under heat stress (30 to 32 ° C) was (Dai ., 2011). Also with the results obtained in Priya and (2010) agrees that showed a 0.5 percent glutamine diet significantly increased the body weight of broilers in the period of 42 days under normal temperature (18- 24 ° C) was. The experiment are likely stress temperatures (31-33 ° C) causes deterioration of broiler body weight is 21 to 42 days and 0.5 % of glutamine supplementation of the duodenum and jejunum through changes in morphology (height Wiley) complications thermal stress is reduced, resulting in improved weight gain.
Although the 0.5 percent improvement in weight but high levels of glutamine in recent experiment (one per cent) had no effect on performance. While consumption of 0.5 percent glutamine separately or in combination with 100 mg of gamma-aminobutyric acid effect on weight gain, feed intake and feed conversion ratio of broilers 21 to 42 days at normal temperatures (18-22 ° C) did not is (Dai, 2011). Yi and (2001) improved the body weight gain in turkey poults fed diets containing a Glutamine percent in just the first week of age were reported, Glutamine had no effect on this parameter in the starter period (0-21), grower (22-42) total period (0-42) did not. Even the Inverse consumption of Glutamine and asparagine at 1% for broiler broilers under normal conditions improved weight gain, feed intake and feed conversion were (De-lian, 2009). In another experiment, consumption of combined Glutamine and glycine levels 0.01 and 0.05 kg improved weight gain, feed intake and feed conversion ratio at weeks 3, 5, 7, 10 in Yue-Huang broilers reared race in normal conditions (18 -20 ° C) is (Shu, 2007). Murakami (2007), Batal and Bartell (2007), Soltan (2009) found 0.5% of Glutamine consumption improves performance of broilers from 1 to 42 days under normal conditions of temperature (18-22 ° C) is. Glutamine a major fuel in many cells of the intestinal mucosa and the cells of the intestinal mucosa (Reeds ., 1997).
Improve the morphology of the digestive system is one of the possible mechanisms of positive effects on Glutamine have improved weight gain. Morphological improvement after the ingestion of Glutamine because some of the studies are specified. For example, 1% Glutamine consumption in broiler chickens grown in normal conditions increase the length and crypt depth at 21 days of age is Wiley (Khempaka, 2011). 1% Glutamine and glutamate levels in pig consumption increased height and increased Wiley and jejunum lamina propria in kids 7 to 14-day-old piglets were. Liu (2002) also observed that consumption Glutamine and glutamate 1% increase in uptake of D-xylose (absorption index carbohydrates) in pigs have been. Glutamine also reduces the microbial population of mucosal transmission (Li, 1994). Therefore, given the important role of glutamine as an essential prerequisite for the synthesis of macro-molecules such as DNA and proteins (Newsholme, 1985), this material is extremely important in the proliferation of epithelial cells of the small intestine and colon mucosal repair (Peng and ., 2004). Another reason is probably due to the beneficial effects of glutamine on the synthesis of nitric oxide plays an important role in this material is determined. Glutamine and arginine plays an important role in the synthesis of nitric oxide and nitric oxide secretion in the regulation of intestinal and digestive system maintenance.
The last possible reason for the beneficial effects on weight gain in recent experiment substance, the immune system can increase heat stress. Research has shown that glutamine supplementation can make digestive irregularities during heat stress conditions improve (Peter, 1997). This amino acid provides a large portion of energy to mucosal cells of the gastrointestinal tract and thereby increasing the rate of lymphocyte proliferation (Windmueller, 1980). Although consumption improves weight gain was 0.5 percent glutamine in our experiments, but the lack of effect of higher levels of glutamine (1%) and other functional parameters were determined on weight gain. While Bartell and Batell (2007) observed that the addition of glutamine caused a significant increase in body weight gain in broilers at normal temperature (18- 22 ° C), respectively. Soltan (2009) stated that the addition of 0.5 and 1% glutamine in the diet had no significant effect on feed intake of broiler chickens is 42 days in normal temperature. Ebadisal (2011) also conducted experiments, the effect of dietary supplementation with glutamine and glutamate levels 0.5 and 1% performance improvement in gastrointestinal morphology in the jejunum and cecum of broilers under heat stress perfringens C. (32 ° C) study and showed that supplementation of the diet with glutamine and glutamate changes in broiler feed up to 35 days does not cause. Soltan (2009) reported that the addition of more than 0.5 percent (1%) of glutamine in the diet can be toxic and cause weight loss. The effect of glutamine supplementation in animals is not so apparent.
So that changes in weight gain of pigs when dietary supplementation with glutamine has been reported (Kitt ., 2002). Yi and (2001) improved the body weight gain of pullets turkeys fed diets with glutamine percent in just the first week of age were reported. Yi (2001) reported that the addition of glutamine to the diet of turkey poults in normal conditions and the weeks after hatching improves the conversion efficiency. Kitt (2002) reported that the addition of glutamine to the diet improves feed conversion in pigs have been weaned. Also in our study, the weight of any of the internal organs Glutamine consumption was not affected. Similar to our results, the consumption levels of 0, 0.5, 0.75, 1% glutamine, no significant effect on tissue weight, thigh, broilers breast grown at normal temperature (Mussini, 2012). In normal conditions of temperature (20-22 ° C), the consumption levels of 0.5 and 1% effect on liver weight of broilers from 1 to 42 days is not (Soltan, 2009).
In a recent study, none of the parameters of blood cholesterol, triglycerides, total protein and hemoglobin were not affected by dietary glutamine. Protein concentration in the blood is a reflection of the ability of the liver to synthesize proteins. Studies indicate that it is total concentration of blood proteins in terms of reduced tension and this would reduce the feed consumption and imbalance of amino acids has been linked and it is reported that glutamine supplementation improved the entire process of making a protein in the blood are animals (Zou, 2006). Although recent research due to the lack of treatment cultured at normal temperature, it was unclear how changes in food intake induced by heat stress. But it seems that the lack of blood protein changes in research recent due to the good balance of amino acids be used ration of this research. It is reported that supplementation with glutamine and glycine may lead to decreased fatty acid oxidation (Shu, 2007).
However, recent research due to the lack of effect of glutamine on changes in blood levels of cholesterol and triglycerides were observed. In vitro, it has been found that providing glutamine can provide 38 percent of the energy required for macrophages (Newsholme, 1985). Processes of cell division in the rat, rabbit and human lymphocytes depends on glutamine is mitosis division. Reconstruction of glutathione in the liver from amino acids glutamate, cysteine and glycine and cysteine are required for the process of sulfur amino acids such as methionine - cysteine is produced in the liver (Tanha, 2011). Glutamine supplementation has no significant effect on meat characteristics (ash, acidity, total protein, dry matter, fat, MDA meat and meat color parameters (A, B and L) was (P > 0.05). The above results Rican Dai and ( 2012) reported that glutamine levels had no effect on the characteristics and meat quality of broilers under heat stress at 28 ° C display. But overall improved survival from the time of the slaughter until the meat is consumed. Acidity of meat with high levels of glutamine consumption was little changed in comparison with the other indicators, this will not change the color of the meat.
It is true that glutamine supplementation had no significant effect on meat color parameters change. In an overview of the Table 5 (Kannan ., 1997) Effect of glutamine supplementation on meat color invoices will realize that glutamine supplementation decreased the concentration of MDA meat was probably caused by the increased concentration of glutathione peroxidase and beneficial effects of this amino acid the reduction reaction is oxidation in meat tissue (Zhu .,2011). In addition, glutamine supplementation improves meat color parameters compared to the control which is likely Goes. It must be remembered texture color components significantly influenced by factors such as diet and environmental conditions, genetic (binam ., 2007). This is caused by meat tissue glutamine in the buffering property through donation of natural acidity and nitrogen groups maintain the texture on the one hand and on the other hand, powering it through the synthesis of private and glycolysis process in the context of which this cause properties to protect against the paleness and reduced water-holding capacity and improves meat tenderness have been slaughtered chickens (Souba, 1990).
It is concluded that glutamine supplementation improves performance by increasing the weight. But was not significant effect on carcass characteristics, blood parameters, and meat quality. Further study on the effect of glutamine supplementation on intestinal morphological status and immune systems of broilers under heat stress done.
This article was originally published in International Journal of Farming & Allied Sciences. Vol., 3 (12): 1234-1242, 2014.