مجله تولیدات دامی
سال بیست و چهارم شماره 1 (بهار 1401)

The aim of the present study was to investigate the performance of the hybrids obtained by crosses of the six Japanese silkworm lines named IRA1, IRA3, IRA5, IRA7, IRA9, and IRA11 and six Chinese silkworm lines named IRA2, IRA4, IRA6, IRA8, IRA10, and IRA12. The new hybrids derived from these lines along with available commercial hybrids (as control groups) for six traits including cocoon weight, cocoon shell weight, cocoon shell percentage, best cocoon weight, pupation rate and best cocoon pupation rate were measured and recorded in spring 2020. The IRA7×IRA6 and IRA7×IRA12 hybrids had more performance in comparison with commercial hybrids in terms of productive traits including cocoon weight and cocoon shell weight (P < 0.01), but, when productive and viability traits (pupation rate and best cocoon pupation rate) were considered together in an evaluation index, they were not among the selected hybrids. Commercial 31×32 hybrid in terms of cocoon shell weight and cocoon shell percentage had more performance in comparison with the other hybrids (new and commercial) (p<0.01). Hybrids had a significant difference for pupation rate and best cocoon pupation rate (P < 0.01), and the IRA5×RA12, IRA1×IRA10 and IRA11×IRA6 hybrids showed the lowest mean for both traits in comparison to other hybrids (P < 0.01). The results obtained from the present study indicated that seven hybrids including IRA9×IRA2, IRA11×IRA2, IRA3×IRA6, IRA3×IRA2, IRA7×IRA4, IRA7×IRA10 and IRA7×IRA8 were greater than the minimum set for every six traits. Therefore, they can be used to supply the country's required silkworm eggs.

The aim of this research was to investigate the immune system responses against sheep red blood cells (SRBC) and Newcastle disease virus (NDV) in two sexes of both wild and Italian speckled quails. To compare phenotypic differences of two sexes for humoral immune responses a one-way analysis was applied, and a simple animal model using the MCMCglmm package of R software was used for genetic analysis, assuming variance components between the two sexes are different. Phenotypic comparison between males and females did not show a significant difference in any of the strains. In both strains, heritability of humoral immunity in males was higher than females. Results indicated that heritability of IgT in males (0.187), and IgY in females (0.177) were higher than other estimates in wild strain. The highest heritability was related to the NDV, which was estimated to be 0.214 and 0.268 in males and females, respectively. Therefore, genetic selection for IgN can be expected to improve the performance of the birds’ humoral immune system. Likewise, according to the higher estimates of immune responses in males, genetic selection of humoral immune responses for IgN, leads to higher genetic progression.

To evaluate the interaction effects of season and dietary forage particle size on milk yield and composition, 100 early lactation Holstein cows in two seasons of spring and summer (each season with 50 heads) in the form of two treatments containing alfalfa forage with large particle size (geometric mean 7.7 mm) and fine particle size (with a geometric mean of 4.2 mm) were used. The amount of dry matter intake of cows was recorded in groups and the milk production of cows was recorded individually.The results showed that milk yield, protein, lactose and total solid percentage of milk were higher within spring compared to summer (P< 0.01). Milk yield (P= 0.09) and milk lactose percentage (P = 0.08) for cows fed fine forage particle size trended to be higher than cows fed long forage particle size. The amount of dry matter intake within two hours after feeding for summer was higher than spring (P< 0.01). Overall, results of the predent study indicated that cows fed with fine forage particle size had more homogeneous feeding behavior pattern within both studied season than cows fed long forage particle size.

Effect of Saccharomyces cerevisiae on growth performance, health index, nutrient digestibility, serum metabolites and feed intake behavior of dairy calves using 18 Simmental dairy male calves aged about 20 days and initial body weight 47±2.4 kg was studied in a completely randomized design with 3 treatments and 6 replications. Treatments included: 1- control group (without yeast), 2- treatment containing 2.5 grams of Saccharomyces cerevisiae yeast per day and 3- treatment containing 5 grams of Saccharomyces cerevisiae yeast per day. The experimental period lasted 60 days, which the first 7 days were considered as adaptation period. Dry matter intake and daily weight gain were measured, and feed conversion ratio was calculated. Digestibility of nutrients and blood metabolites were also determined. The calves received 5 grams of yeast had higher weight gain and better feed conversion ratio (P<0.05). Blood glucose, cholesterol, triglyceride, and nitrogen urea concentrations were not affected by experimental treatments. The digestibility of dry matter was higher in dairy calves consuming 5 grams of yeast than the control group (P< 0.05). According to the results of the present study, the use of yeast increased daily weight gain and dry matter digestibility and improved feed conversion ratio. Therefore, Saccharomyces cerevisiae yeast can be used in dairy calf diets at a level of 5 grams per day.

The effect of Betaplus probiotic in the diet on growth performance and histomorphometry of Japanese quail jejunum was investigated by using 288 broiler chicks with 6 treatments, 4 replications and 12 birds per each in a completely randomized design from 1 to 42 days of age. The experimental treatments included: control group (without additives); three diets containing levels of 0.5, 1 and 1.5 g/kg of Betaplus probiotic; diet with deficient in protein, and diet with deficient in protein and contained 1 g/kg of Betaplus. Feed intake, and body weight gain were measured weekly and feed conversion ratio was calculated. At 42 days of age, two birds were randomly selected from each replicate and the traits related to carcass dissection were assessed. For histomorphometrical evaluation of the intestine, the jejunum samples were collected. The utility of Betaplus probiotic at level 1 g/kg improved food intake, weight gain, conversion factor and some histomorphometrical parameters of jejunum (P< 0.05). In birds were fed with level of 1.5 g/kg Betaplus, the villi thickness and crypt diameter and number of the goblet cells were decreased (P< 0.05). According to the results, the use of Betaplus probiotic at level 1 g/kg in the diet improves the growth performance and histological parameters of the jejunum in Japanese quail.

This study was performed to investigate the relationship between apparent digestibility of magnesium (Mg) with body weight, feed intake and phytase enzyme with 120 individual B-line Arian male broilers. Birds were assigned two standard diets and a diet supplemented with one gram of phytase (FTU / 500 kg). Daily feed intake, weekly weight gain, feed conversion ratio during rearing and Mg digestibility were measured at 28 to 30 days. Using Gompertz model, growth rate (c), initial weight (b) and maximum growth potential (m) were analyzed. Growth rate and maximum growth potential were higher in the group fed phytase enzyme (P <0.05). Weight gain and feed conversion ratio improved under the effect of phytase supplemented diets (P <0.05). Magnesium digestibility was higher in phytase enzyme diets than standard basal diets (P <0.05). The results showed that the modeled growth rate affected the Mg digestibility, so that birds with higher growth rate (faster growth potential) had more potential for Mg digestion (P<0.05). The relationship between Mg digestibility and body weight gain was positive and with increasing Mg digestion, weight gain improved (P<0.05). Birds with higher growth potential have the ability to digest more Mg, and this digestibility is increased by the use of the phytase enzyme. Therefore, in the breeding programs of Arian chickens, more attention can be paid to the relationship between the use of Mg and the growth rate parameter.

The effects of valine supplementation on performance, immunity and behavioural indices of broiler chickens under heat stress condition was evaluated. Total of 420 male and female Ross-308 broiler chickens were allocated to 6 treatments with 5 replicates in a completely randomized design. Experimental groups were as fallows: positive control (fed basal diet and reared under Ross-308 recommended rearing temperature), nagative control (fed basal diet and reared under heat stress (HS)), and four treatment groups fed basal diet supplemented with 5, 10, 15 and 20% valine above the Ross-308 valine recommendation and reared under HS. Heat stress significantly decreased feed intake, body weight and European production efficiency factor (EPEF), antibody titer against NewCastle, lymphocyte percentage, serum total protein concentration and alkaline phosphatase and lactate dehydrogenase activities and increased heterophile percentage, heterophile to lymphocyte ratio, rectal temperature and tunic immobility of broiler chickens (P< 0.05). Supplementation  of5% valine improved BW of broiler chicken at the end of grower and BW and EPEF at the end of total period. Addition of  10% valine increased relative weight of breast and thigh muscle and 15 and 20% valine supplementation increased lymphocyte and decreased heterophile percentage as compared to control group (P< 0.05). In conclusion, 5% valine supplementation improved final body weight and feed convertion ratio of heat-stressed broiler chikens and 15 and 20% valin inclusion improved blood immune cell percentages but had no effect on humoral immune response and tunic immobility test of HS broiler chickens.

Effect of different levels of calcium (0.3 and 0.6%), phytase (0 and 1500 FTU/kg), and citric acid (0 and 1%) in diets containing 0.15% of non-phytate phosphorus, on growth performance, carcass traits, and bone chemical properties were investigated using 882 10-day-old male broilers from 11 to 40 days of age in 2×2×2 factorial arrangements based on a completely randomized design including 9 treatments (positive control and eight diets without any inorganic phosphorus) and 7 replications. The supplementation of phytase increased average daily gain and gain to feed ratio, but the effect of phytase was more apparent in broiler chickens received diets containing 0.6% calcium at 25 to 40 days of age (P< 0.01). Reducing dietary calcium levels decreased average daily gain (11 to 24 days) and gain to feed ratio (11 to 24 and 25 to 42 days). Also, the inclusion of citric acid in diets containing 0.3% calcium had a negative effect on these traits (P< 0.01). The combination of phytase and citric acid in diets containing 0.6% Ca increased the feed efficiency compared to the 0.3% diet (P< 0.01). Phytase supplementation increased toe ash and bone sodium percentage and decreased bone calcium and phosphorus concentration (P< 0.01). Bone phosphorus decreased by reducing dietary calcium levels and phytase supplementation (P < 0.01). The relative heart and pancreas weight decreased with phytase supplementation (P< 0.05). Reducing dietary calcium levels increased the relative liver and pancreas weight and decreased abdominal fat and heart percentage (P< 0.05). According to the results, the combination of phytase and citric acid in diets containing 0.6% calcium was more effective in improving growth performance of broilers fed diets containing low non-phytate phosphorus.

In order to investigate the effects of different periods of thermal manipulation during embryogenesis on thermotolerance, hatchability and blood parameters of Ross (308) broilers strain, 608 fertile eggs were used in a completely randomized design of 4 treatments with 4 replicates. Experimental groups with different thermal manipulation (for control (0 h), 6, 12 and 18 hours) where incubated at 65% humidity and 39.5°C from 7 to 16 days of incubation. At 7 d of incubation, the infertile and undeveloped eggs were removed after the candling. The result showed that thyroid hormones and facial surface temperature, as metabolism and thermotolerance index, decreased significantly in 6-, 12- and 18-hour-treated groups compared to the control group (P< 0.05). The hatchability was higher in the eggs exposed to 0, 6- and 12-hour thermal manipulation than in the other groups, and a reduction of hatchability was observed in the 18-hour treatment group (P< 0.05). Hatching time increased significantly in the thermal-treated groups (P< 0.05), whereas experimental treatments did not affect body weight, body length, and quality of chickens. Yolk sac percentage was higher in the treated groups than in control (P< 0.05). Increasing the length of thermal manipulation increased the female sex ratio (P< 0.05). The blood concentration of uric acid and total protein significantly decreased in 6-, 12- and 18-hour treatment groups (P< 0.05). In conclusion, based on the results of this study, 6 and 12 hours of thermal manipulation induced thermotolerance without adverse effects on hatchability.

The aim of this study was to investigate the changes in some blood parameters in 15 Lori ewes during pregnancy and compare it with one month before pregnancy and lactation. Blood samples were taken from the jagulur vein before normal mating as a control, at the end of every three months of pregnancy and two weeks after delivery during lactation, and the complete blood cell count of each sample was evaluated by a veterinary cell counter. Giemsa staining and differential white blood cell count were performed on blood smears and total plasma protein values ​​were evaluated by refractometry. The number of red blood cells and the percentage of hematocrits during lactation were significantly reduced compared to pregnancy (P˂0.05). Mean cellular volume was reported in all periods in one spectrum. The Decrease in the mean hemoglobin levels of red blood cells, mean hemoglobin concentrations in red blood cells and platelet count in pregnancy were observed compared to before mating. The number of leukocytes and neutrophils increased around parturition and decreased after parturition. During pregnancy, the number of eosinophils increased significantly and decreased after parturition (P˂0.05). The number of monocytes and lymphocytes increased in late pregnancy and decreased during lactation (P˂0.05). The amount of total protein in the plasma decreased significantly from 100-150 days of pregnancy (P˂0.05). Thus, base on the results of the present study monitoring of changes in blood parameters of Lori ewes, dietary adjustment and preventive measures are necessary to prevent blood disorders such as anemia and thrombocytopenia.