فصلنامه تحقیقات تولیدات دامی
سال سیزدهم شماره 4 (زمستان 1403)

Glutamine represents approximately 30-35% of the total amount of nitrogen in the blood derived from amino acids. The role of glutamine as a nitrogen shuttle helps to protect against the toxic effects of high levels of ammonia in the blood. In addition, glutamine has vital and specific metabolic functions as a vehicle for carbon exchange between tissues, as a fuel for rapid cell division, and as a precursor of many naturally active molecules. It's a great example of how amino acids are used for different purposes in the metabolism and the immune system of the body. Glutamine, a conditionally essential amino acid, seems to be a key nutrient for the gut, as it may be a prominent source of vitality for the enterocytes. Glutamine appears to trigger an increase in the level of intestinal secretory immunoglobulin A, which is essential for mucosal defense. The investigation showed that the use of amino acid supplements in broiler diets improves the performance and the carcass characteristics. Glutamine is one of the most abundant amino acids in blood plasma and is involved in the building of muscle, and tissue, and gaining body weight. Researchers found that adding 10 g of L-glutamine per kg of food increased the weight gain and serum immunoglobulin A and G concentrations in broiler chickens. Therefore, an experiment was carried out in broiler chickens over 42 days of production to determine the effect of L-glutamine on broiler growth, carcass quality, and certain blood parameters.

The experiment was conducted using 300 one-day-old male Ross 308 broiler chickens in a completely randomized design with five treatments and five replicates from the age of 1 to 42 days. The experimental treatments included were: the addition of zero, 0.25, 0.5, 0.75, and 1% of L-glutamine in corn-soybean meal-based diets supplemented with dietary fat. During the experimental period, average daily feed intake (DFI), body weight gain (BWG), and feed conversion ratio (FCR) were measured. At the end of the experiment, two birds were selected from each replicate and slaughtered after weighing, and the weight of the internal organs (thigh, breast, heart, liver, gizzard, fat pad, pancreas, bursa, spleen, and thymus) was measured. Blood samples were collected from two birds per replicate to determine the number of white blood cells (WBC), and heterophile to lymphocyte ratio (H/L). Blood samples were taken from the jugular vein in tubes without anticoagulant and then centrifuged (2000×g for 10 min) to obtain a serum. On the 42nd day of rearing, serum cholesterol (total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL)) and triglycerides were determined by calorimetric examination.

Weight gain during the initial and growth periods was affected by L-glutamine supplementation (P<0.05). Despite higher feed intake for L-glutamine-supplemented diets during the initial period, this effect was significant only during the growth period (P<0.05). FCR and relative weight of internal organs, except liver weight, were not significantly different from the control group in the L-glutamine-supplemented chickens. The addition of 0.5% L-glutamine supplementation reduced cholesterol and triglyceride content and increased HDL in the blood of broilers (P<0.05). The H/L ratio in chickens that consumed L-glutamine was significantly lower than in the control group (P<0.05). L-glutamine has been reported to increase the activity of the intestinal enzyme Na-K ATPase, thereby indirectly increasing the absorption capacity of nutrients such as glucose and amino acids in the intestine. Researchers reported that L-glutamine increases the performance and feed intake of chickens by improving intestinal function and increasing digestibility. Expanding the villi of the small intestine can increase digestion and feed intake by increasing nutrient absorption and thus improving chicken performance. Improving the morphology of the digestive system is one of the possible mechanisms of the positive effect of L-glutamine on improving weight. Since glutamine stimulates anabolic conditions in the body and increases the amount of protein synthesis, therefore, along with muscle growth, it can increase the final body weight. Avian health is directly related to the immune system, and birds with adequate immune systems grow better. The majority of essential amino acids are recognized as critical resources for cytokine production and immune function.

Results from this study indicate that 0.5% dietary glutamine supplementation improved growth performance and had a positive effect on lipid metabolism-related blood parameters.

 In poultry breeding farms, density is one of the important factors in terms of welfare, production, and health in poultry. Density can be defined as the number of birds per unit area or kilograms per unit area. High density reduces body heat loss, bad air quality due to its improper exchange, increased ammonia level, and reduced access to food and water, which leads to reduced feed efficiency. It seems that the stress caused by high density can upset the balance of the microbial population of the digestive system. Improving the microbial population of the gastrointestinal tract through the addition of different sources of insoluble fiber may be beneficial for the development of the health and growth performance of broiler chickens grown at high densities. In Iran, rice hull is obtained as waste from rice grain processing, which contains a high percentage of insoluble fibers. Sunflower husks, as a byproduct, contain a significant amount of fiber. On the other hand, the sunflower hull is the outer covering of the sunflower seed. Sunflower hull and rice hull have high fiber and low energy. Considering the negative effects of high density and the positive impact of fibrous sources, the present study investigated the influence of different insoluble fiber sources on the performance and microbial population of the caecum in broiler chickens raised at high density.

 The experiment was performed with 390 one-day-old broiler chicks of Ross 308 strain in a completely randomized design with a 2×3 factorial arrangement and five replications. The experiment included two density levels (10 and 16 birds per square meter) and three fiber sources (diet without fiber, diet containing sunflower hull, and rice hull). Characteristics of feed intake, body weight gain, and feed conversion ratio were measured regularly and blood factors and bacterial counts were sampled on the last day after slaughter.

 There was no significant difference between the fiber source and density in different growing periods on average feed consumption and relative weight of different carcass components (P<0.05). High density resulted in a decrease in feed intake in the starter, finisher, and overall period compared to normal density (P<0.05). Birds fed with different fiber sources showed higher feed intake compared to the control treatment in the growth, finisher, and overall period of the experiment (P<0.05). Birds fed with a diet containing sunflower hull and rice hull in normal density conditions showed higher weight gain compared to other treatments in the final period. The best feed conversion ratio was observed in the rice hull treatment at the normal density level in the final and overall period of the experiment (P<0.05). Birds fed with sunflower hull in normal density and rice hull in high density showed a significant increase in blood HDL concentration compared to other treatments (P<0.05). Birds reared at high density showed significantly higher blood glucose, cholesterol, and LDL concentrations compared to birds reared at normal density (P<0.05). It may be the reason for the increase in LDL, glucose, and blood cholesterol concentration in high density, negative responses such as an increase in corticosterone level, an increase in lipid peroxidation, production of free radicals, and an increase in immunosuppression in chickens reared in high density. The interaction effect of fiber source and density level had no significant effect on Coliform and Escherichia coli populations in cecum (P<0.05). In the presence of sunflower hull and rice hull, high density led to a significant increase in the population of cecal Lactobacillus compared to normal density (P<0.05). In the absence of fiber, high density caused a significant decrease in the cecum Lactobacillus population compared to normal density (P<0.05). Diet is a major environmental factor that can directly affect the nature of the microbiota in the host.

 The results of this study showed that the use of fiber could improve the feed conversion ratio in high-density rearing conditions compared with birds fed a diet free of fiber and in normal-density rearing conditions. In addition, the use of sunflower hull and rice hull led to increased feed intake, weight gain, cecal Lactobacillus population, and improved feed conversion ratio in broiler chickens. Compared to birds reared at normal density, birds reared at high density showed a decrease in feed consumption, a decrease in weight gain, and an increase in the population of the cecal Coliform population.

The principal aim of the dairy sheep industry worldwide is to produce high-quality milk. Mastitis is an inflammatory disease in dairy animals that occurs in response to infectious factors and has substantial impacts on animal health, and economic profitability. Somatic cell count has been used as an indirect method to control mastitis. Genetic resistance to mastitis involves linked biological mechanisms resulting from differences in mastitis response, which activate and regulate different levels of the immune response. Over the last decade, interest in identifying genes or genomic regions targeted by selection has grown. Identifying selection signatures can provide valuable insights into the genes or genomic regions that are or have been under selection pressure, which in turn leads to a better understanding of genotype-phenotype relationships. This study aimed to identify effective genes and genomic regions under positive selection in two sheep breeds using selection signature methods. For this purpose, FST and hapFLK analyses were performed using the genome-wide single nucleotide polymorphisms (SNPs).

In this study, data from 585 sheep of different breeds were used to identify genomic regions under selection related to the somatic cell counts in milk. Illumina ovine Bead Chip 50K was used to determine the genotype of the samples. The genomic information of sheep breeds was extracted from the Zenodo database. Quality control on genotyped samples was performed using PLINK v1.9. SNPs with a minor allele frequency (MAF) of less than 0.02 and those with a call rate of less than 0.97 were excluded. In addition, individuals with more than 10% missing genotype data were removed. SNPs that did not conform to Hardy–Weinberg equilibrium (P<10-6) were also eliminated. Following these quality control measures, 41,673 SNPs from 585 sheep were retained for further analysis. To identify the signatures of selection, two statistical methods of FST and hapFLK were used under the software packages FST and hapFLK, respectively. The candidate genes were identified using PLINK v1.9 software and the Illumina gene list in R by SNPs located in the 0.01 percentile of FST and hapFLK values. In addition, the latest published version of the animal genome database was used to define QTLs associated with economically important traits at identified loci. The GeneCards (http://www.genecards.org) and UniProtKB (http://www.uniprot.org) databases were also used to interpret the function of the obtained genes.

Using the FST approach, nine genomic regions on chromosomes 2, 5, 7, 10, 11, 13 (two regions), 17, and 22 were identified. The identified candidate genes associated with somatic cell count in these genomic regions included IL11RA, CDC16, CARD14, BTRC, OTUD4, COL23A1, LACTB, and PRELID3B. Some of the genes located in the identified selection regions were associated with the immune system, innate immune response, inflammation response, cancer disease, and milk production. Some of these genes in the selected regions were consistent with previous studies. The investigation of reported QTLs showed that these regions are related to QTLs of important economic traits, including milk somatic cell count, udder height and depth, clinical mastitis, bovine tuberculosis susceptibility, and heat tolerance. Moreover, the results of hapFLK statistics in this research led to the identification of six genomic regions on chromosomes 3, 4, 5, 7, 10, and 13. The identified candidate genes associated with the somatic cell count in these genomic regions included FAM49A, CDK6, and DLGAP5. Bioinformatics analysis demonstrated that some of these genomic regions overlapped with known genes related to innate immune and various cancers.

Different genes that emerged in the aforementioned regions can be considered candidates for selection based on their function. It was found that most of the selected genes were consistent with some previous studies and were involved in production traits. However, further investigation is recommended to determine the exact function of the identified genes and QTLs. These areas should also be confirmed by other independent studies using larger samples. In general, the data from this study may be used in research on genomic selection and genomic regions associated with mastitis in dairy sheep and in further reviews and evaluations for the improvement of dairy sheep production.

 Wheat grain is normally used for animal feed in some regions, but is seldom used in others. Its nutritional composition is very similar to that of the barley grain commonly used, but there are concerns about its effects on the performance and health of the animals. Wheat seed is one of the grain varieties with the highest amount of protein available for animal feed, exceeding corn. Furthermore, it has a high energy value of 3.0 to 3.5 Mcal of ME (metabolizable energy), which is an important source of energy for animal feed. The most abundant carbohydrate in wheat is starch, a digestible polysaccharide. On the other hand, it is recommended that wheat has a moisture content of less than 14% to avoid problems with digestibility and contamination by mycotoxigenic fungi. Barley is an important grain which is widely used as a source of feed for ruminants. Feed deliveries during the fattening period are the physical processing of the feed. It has been demonstrated that barley starch ferments rapidly in the rumen. The high digestibility of barley has raised concerns regarding acidosis, lameness, liver abscesses, and gastrointestinal abnormalities in ruminants. It is generally considered that the processing of barley grain may be used in the feed industry to adjust the rate of digestion of its nutrients to avoid acidosis. Consequently, the distribution of particle sizes after processing is one of the main factors influencing the rate and extent of digestion of barley (feeding of livestock accounts for 65-70% of the cost of raising livestock). Wheat and barley are used as the predominant source of energy for animal nutrition in most parts of the world. Wheat seed has been used for a long time because of the extensive cultivation and livestock rearing in Iran. The most common way of processing barley and wheat grain in the country is by grinding. Farmers prefer to use whole grains in the production of concentrates, as the concentrate involves the use of crushed grains, but the farmer's wish to use whole grains in the concentrate requires a study and field investigation. The purpose of this study is therefore to examine the effects of the grain size of barley and wheat on the diet of lambs fattening and to compare their effects on growth performance, digestibility, rumination and blood parameters.

 This experiment was carried out in the form of a completely randomized design with a factorial arrangement of 3×2 with six treatments including 1. Finely milled barley grain with sieve number two, 2. Coarsely milled barley grain with sieve number eight, 3. Unmilled barley grain, 4. Finely milled wheat grain with sieve number two, 5. Coarsely milled wheat grain with sieve number eight, and 6. Unmilled wheat grain. Five fattening lambs aged 4-5 months with almost the same starting weight were allocated to each treatment and a total of 30 male lambs were individually tested for 98 days, including two weeks for acclimatization and 84 days for the remainder of the main test period. The performance of lambs was assessed in this experiment, including average daily feed consumption, daily weight gain, final weight, and feed conversion ratio. Nutrient digestibility was measured by the acid-insoluble ash (AIA) method from day 80 for four days. The digestibility of dry matter organic matter, crude protein, ether extract, and neutral detergent fiber was evaluated. Blood parameters were measured including blood glucose, blood cholesterol (LDL-c, HDL-c), and blood urea nitrogen (BUN).

 The results showed that daily weight gain was significant throughout the treatment period and daily weight gain was greater in the treatment group that consumed barley than in the treatment group that consumed wheat (P<0.05). The impact of the grain, the type of processing, and their interaction on feed consumption in all three experimental periods was not significant. Total feed consumption was not significant, but it was significant during the last month of fattening (P<0.05). Lambs consuming barley and wheat milled with sieve number eight had the highest feed consumption compared with the treatment of wheat and barley with sieve number two and whole grains (P<0.05). The feed conversion ratio in treatments receiving wheat was higher than that in those receiving barley (P<0.05). The type of processing had no significant impact on the feed conversion rate (P>0.05). In the study of nutritional behavior, the results showed that the parameters of eating and rumination were higher in the treatments receiving wheat compared to barley (P<0.05). Also, the treatments receiving unmilled barley and wheat (whole grain) showed the highest levels of eating and rumination (P<0.05). The treatments receiving barley and wheat grains with sieve number two also showed the lowest levels of eating and rumination. There were no significant differences in nutrient digestibility, rumination parameters, and blood parameters (P>0.05). Contrary to the view of the farmers that whole grains are better than milled grains, the results showed that overall the use of ground or whole grains did not show a significant difference.

 Overall, the results showed that there was no significant difference between whole grain and milled grain, and even from the point of view of palatability, milled grain with a sieve number 8 had a higher consumption rate than the other treatments. These findings indicate that milled barley grain with a sieve number 8 may be used as a substitute for whole barley grain in the feeding of lambs.

 Animals need vitamins A, D3, and E to improve their performance and health. Vitamin A has an active role in maintaining all epithelial cells in the body and plays an important role in bone growth. Vitamin D3 plays an important role in increasing the absorption of calcium and phosphorus, in addition to the formation and calcification of the bones in animals. Vitamin E is a fat soluble vitamin which is both a growth-promoting vitamin and is considered an antioxidant. These vitamins also play an important role in improving the immune system in ruminants. Ruminants cannot produce vitamins A, D3, and E in their body; therefore, to meet physiological requirements and maintain high production performance, they need to be provided with an exogenous regular intake of vitamins A, D3, and E in their diet. Several studies have been carried out on the effects of dietary or injectable vitamin AD3E supplements on fattening lambs. This study aimed to determine the effects of various forms of AD3E supplementation on growth performance, rumen fermentation, protozoa population, and blood parameters in Mehraban lambs by in vivo and in vitro experiments.

 The project comprised two in vitro and in vivo experiments. In this experiment, the in vivo growth parameters such as final body weight, total weight gain, average daily gain, average daily gain, dry matter intake, feed conversion ratio, the ruminal fermentation parameters such as pH, ammonia nitrogen, total volatile fatty acids, blood biochemical metabolites [blood urea nitrogen (BUN), cholesterol, triglyceride, glucose, albumin, HDL, LDL, and malondialdehyde (MAD)], protozoa count, and in vitro gas production, organic matter digestibility, methane gas production, metabolizable energy, and short-chain fatty acids were studied. This experiment consisted of a 14-day adaptation period and a 60-day experiment. Twenty Mehraban lambs (body weight of 41.3±0.5 kg) were divided into four groups with five replicates in each group using a completely randomized design. The treatments included 1) the control group received a base diet without vitamin supplements, 2) injectable vitamin AD3E, 3) rumen-protected vitamin AD3E as a part of concentrate, and 4) AD3E vitamin in drinking water. Feed intake and body weight of lambs were recorded weekly during the fattening period. The samples of blood and rumen liquid were collected from the lambs on the 30th and 60th days of the experiment.

 The results indicated that the gas production, digestible organic matter, metabolizable energy, and short-chain fatty acids were reduced due to vitamin AD3E supplementation compared with the control group (P<0.05). Growth performance was not different when supplemented with AD3E, but for the rumen-protected vitamin, the average daily increase was 48 g more than that in the control group. The feed conversion ratio showed a significant decrease in AD3E water-soluble vitamins compared with the control group (P<0.05). The pH was not influenced by experimental treatments. The ammonia concentration was higher in treatments 3 and 4 (P<0.05), and the protozoa count was reduced due to vitamin AD3E supplementation (P<0.05). The BUN serum concentration was lower in treatments 2 and 3 compared with other treatments (P=0.008). Vitamin supplementation with AD3E administered in water or its injection made a significant increase in cholesterol concentration (P=0.002). Blood concentration of triglyceride showed a significant increase in treatment 4 (P=0.007). Plasma concentration of HDL was lower in lambs who received rumen-protected AD3E compared to the control group (P<0.05). Experimental treatments did not affect plasma glucose, total protein, albumin, LDL, and MAD concentrations of fattening lambs (P>0.05). Plasma concentration of BUN on day 60 was higher compared to the 30th day in all treatments (P<0.05). However, plasma concentrations of triglyceride and glucose were lower on day 60 compared to the 30th day of the experiment in all groups.

 Results showed that vitamin AD3E had no significant effect on growth performance; however, it was greater in the vitamin group treated with rumen protection than in the control group. Gas production, protozoa population, and ammonia nitrogen decreased compared to control. Higher doses of vitamins, especially the rumen-protected vitamin AD3E, are recommended in larger sample sizes and for longer periods.

 In ruminants, vitamin B12 is a cofactor for two enzyme systems that are involved in many metabolic processes, such as the metabolism of carbohydrates, lipids, some amino acids, and DNA. Vitamin B12 in ruminants is synthesized by rumen bacteria or provided by dietary sources. Vitamin B12 deficiency may result in poor growth, anemia, and reduced milk production in lactating animals. In young ruminants such as newborn lambs and calves, the rumen is not fully developed for vitamin B12 synthesis until six to eight weeks of age. This means that during this period, a dietary source of vitamin B12 is necessary. Colostrum, milk, or milk replacers may be used as a source of vitamin B12 in these young ruminants. However, different factors, including nutritional deficiencies, may affect the vitamin B12 content in milk. This study aimed to investigate the effects of vitamin B12 intramuscular injection on the lactation performance of ewes and on certain blood parameters in their lambs.

 The current research was conducted at the animal husbandry station of Lorestan University.  Twenty early lactating ewes (60±0.50 kg) were selected and allocated to one of the two groups (10 ewes per group). Treatments included 1. Ewes without vitamin B12 injection (control group) and 2. Ewes with a weekly injection of vitamin B12. The first injection of vitamin B12 was given immediately after the ewes were lambed and three further injections were given per week (four injections in total). The amount of vitamin B12 injection was 1 mg intramuscularly in each injection. Milk production was recorded during the 10th, 20th, and 30th days of lactation, and the lambs were separated from their mothers for 12 hours, at which time they were weighed using a digital scale for 10 minutes. The lambs were allowed to use their mother's milk. Immediately after separation from their mother, lambs were weighed again and the difference in weight before and after milk consumption was recorded. The milk composition (including milk protein, milk fat, fat-free solids, palmitic acid, stearic acid, oleic acid, polyunsaturated fatty acids, monounsaturated fatty acids, and total unsaturated and unsaturated fatty acids) was measured with DA 7250 NIR Auto-analysis. To check the blood parameters of lambs, blood samples were taken from the jugular vein of newborn lambs at 10, 20 and 30 days of age, and from two separate tubes, one for the count of cells and one for the measurement of serum concentrations of vitamin B12 and other metabolites in the blood. Vitamin B12 concentrations were measured using the Pars Azmoun kit and the ELISA device. The data analysis was carried out with SAS statistical software (version 9.4). The comparison of the means was done using a t-test with a significance level of 0.05.

 Results showed that milk yield in the vitamin B12 group were significantly higher than that in the control group during the four weeks of the experimental period (P<0.05). This increase in milk production can be considered a response to the increased availability of plasma glucose for milk lactose production by increasing plasma vitamin B12 concentration and its vital role, such as participating in many metabolic pathways in the body and acting as an intermediary in the catabolism of some amino acids. However, the percentage of milk compounds, including milk fat, protein, solids not fat, palmitic acid, stearic acid, oleic acid, mono- and polyunsaturated fats, and saturated fats, was unaffected by the administration of vitamin B12 (P˃0.05). Blood vitamin B12 concentration was significantly higher in vitamin B12 injected ewes compared with the control group (P<0.05). There was no significant difference in growth performance, average wean weight, average birth weight, or daily weight gain of lambs born to vitamin B12-treated ewes compared to control lambs (P>0.05). Injection of vitamin B12 into pregnant ewes had no significant effect on the blood glucose, white blood cells, hemoglobin concentration, red blood cells, or hematocrit percentage of the newborn lambs (P>0.05). Vitamin B12 status in suckling lambs can be related to the rate of transfer of this vitamin through milk during lactation and through the placenta during pregnancy.

 Consequent intramuscular administration of vitamin B12 to ewes at the beginning of lactation may increase milk production and thereby increase the lambs' performance and vitamin B12 concentration in the blood.

 Microelements in organisms have several structural, catalytic, and regulatory functions and play an important role in the functioning of the immune system. The trace mineral content of colostrum and milk is not optimal and in suckling calves, the inclusion of trace mineral supplements in the diet is necessary. Selenium (Se) is a basic mineral for humans and animals and has now been identified as an integral component of more than 35 selenoproteins which are involved in enzymatic, structural, or as yet unidentified functions. In livestock, Se is important for fertility and the prevention of diseases. Sufficient intake of Se increases fertility and enhances antioxidant protection systems and immunological potential. Se deficiency in cattle is associated with several problems, including delayed conception, muscular degenerative disease in calves, myocardial necrosis, heart failure, impaired immune function, increased risk of mastitis, abortion, perinatal mortality, and growth retardation in young calves. Based on the recommendation of the National Research Council, the daily requirements for Se and vitamin E in growing calves are 0.30 mg and 40 IU, respectively. To avoid Se deficiency and to promote animal health, inorganic sources of Se (sodium selenite and selenium) are routinely used as a supplement to the diet of farm animals. Zinc is involved in over 300 enzymes either as a component or as an activator. Zinc (Zn) is involved in immunity, metabolism, growth, and reproduction. It plays a role in the structure and function of antioxidant enzymes. Due to mineral interactions, the inorganic forms are less bioavailable in the gastrointestinal tract. The aim of this study was therefore to assess the effects of supplementation with sodium selenite and Zn oxide on growth performance, immune response, blood parameters, and antioxidant status in Holstein calves.

 The calves were kept in well-ventilated sheds with concrete floors and with individual feeding and watering facilities. The basal diet was prepared from locally available feed ingredients to meet the nutritional requirements of calves growing except for Zn and Se. Calves are fed milk at 10% of body weight in the morning and evening. The experiment started at four days of age and the calves were kept in individual pens for up to 42 days. The study used 36 Holstein calves with an average weight of 34.5±2 kg over 42 days in a completely randomized design. The basal diet (containing 40 mg Zn and 0.15 mg Se) was without Zn and Se supplementation (diet 1). Diet 2 contained 0.3 mg sodium selenite, diet 3 contained 40 mg Zn oxide, diet 4 contained 55 mg Zn oxide, diet 5 contained 0.3 mg sodium selenite + 40 mg Zn oxide, and diet 6 contained 0.3 mg sodium selenite + 55 mg Zn oxide. Feed intake was calculated daily, and calves were weighed weekly to calculate the feed conversion ratio and average daily gain. Blood samples were taken on days 20 and 42 to determine trace mineral levels in plasma and biochemical, enzymatic, hormonal, antioxidant, and hematological parameters. Data on growth and blood parameters were analyzed using the GLM procedure of the SAS program. Significant difference between treatments was determined by Duncan's test and the results were considered significant if the P-value was less than 0.05.

 The results showed that the use of sodium selenite and different levels of Zn oxide did not have a significant effect on feed intake, final weight, body weight gain, growth performance, and immune response (P>0.05). No significant differences in blood metabolite concentrations were observed between treatments (P>0.05). Supplementing milk with 0.3 mg sodium selenite and 40 and 55 mg Zn oxide significantly increased the activity of superoxide dismutase and decreased the levels of malondialdehyde and aspartate aminotransferase (P<0.05). Se plays a role in the defense against the accumulation of hydroperoxides from cellular metabolism. This biological function is mediated by selenoproteins such as glutathione peroxidase (GPx), iodothyronine deiodinases, and thioredoxin reductases, of which selenium is a structural component. Se also acts on enzymes involved in the production and regulation of thyroid hormones and is recognized as a factor in immunological function. The role of Zn as an antioxidant and its role in cell replication and proliferation are the two most directly related links between Zn and the immune system.

 Supplementing milk with Zn oxide and sodium selenite improved the antioxidant status and helped to relieve the stress experienced by suckling calves.