نشریه علوم دامی (پژوهش و سازندگی)
پیاپی 136 (پاییز 1401)

In the management of camel breeding, weightlifting plays a decisive role in grouping livestock, regulating nutritional needs and also annual evaluation of animals. Due to the many difficulties and risks, camel owners usually prefer alternative methods such as using apparent estimates or weight -meter to estimate the weight of camels. Since the accuracy of mathematical models in estimating the weight of camels is not equal, so the present research was conducted to compare the accuracy of estimating artificial neural network and multiple linear regression model in estimating the weight of dromedary camels from their body dimensions. For this purpose, 26 camels with 203 records were used from a private farm for one year. Weighing and determining the body dimensions of camels (body length, shoulder height, back height, hump height to the ground, chest and abdomen girth) were measured monthly. To estimate the weight of camels from their body dimensions, the data were analyzed using multiple linear regression model and artificial neural network. The weight of camels on their body dimensions was estimated with accuracy of 0.94 and 0.99, respectively, using multivariate linear regression model and artificial neural network model. The weight of camels on their body dimensions was estimated with accuracy of 0.94 and 0.99, respectively, using multivariate linear regression model and artificial neural network model. The results of this research showed that the artificial neural network has the proper ability to estimate the weight of camels based on their body dimensions and can replace conventional regression methods.

This study was conducted for predicting performance traits of the whole production period of Arian broiler breeder via its initial performances using artificial neural network (ANN). The input variables of modeling were house, number of hens in the house, weeks of production, body weight at 20-24 weeks of age and outputs of the model were body weight, egg number, egg mass, egg weight and feed intake at the 25 to 47 weeks of age. The used ANN model for prediction of body weight had 5 inputs, 5 neurons at 1st hidden layer, 2 neurons at 2nd hidden layer and 1 output, thus we write it as 5-5-3-1. Similarly, the optimized ANN model structure for feed intake, egg number, egg weight and egg mass were 7-7-4-1, 8-8-4-1, 7-7-3-1 and 7-7-3-1, respectively. R2 of adequate models for BW, FI, EN, EW and EM were 0.991, 0.998, 0.989, 0.993 and 0.996, and Root Mean Square Error were 1.55, 0.992, 0.266, 3.838 and 0.506, respectively. The results of the study shown that architecture and the specification of the neural networks such as inputs, outputs, number of neurons and number of hidden layers can affect the performance of the ANN model. The results indicated the possibility of predicting whole production period of Arian broiler breeder using early stage production records.

The aim of this study two-hundred Holstein dairy cows were selected and used in 4 free stall barn in a completely randomized rotating design. Sixty cows (30 cows per pen) of selected animals with the same characteristics (DIM: 180 ±15, average milk production 49±5, lactation number 2.95) were used for blood and milk sampling. Experimental treatments include control diet (diet 1) based on corn silage and experimental diet (diet 2) replacing 5% of corn silage with barley silage. The results showed that if barley silage is replaced at 5% level with corn silage so that other nutrients in the diet do not change significantly, it had no significant effect on milk production and composition, however, it significantly reduced (p <0.05) the feed intake in the experimental group that received barley silage. In addition, experimental treatments caused a significant increase in blood urea compared to the control group. Replacing barley silage at 5% level with corn silage also significantly increased the percentage of ruminal propionic acid, and had no significant effect on other ruminal parameters. Barely silage also increased the apparent digestibility of dry matter, protein and neutral and acidic detergent fiber. The results of this study showed that barley silage can be replaced with corn silage at the level of 5% without negatively affecting production performance.

This study was conducted to evaluate the effects of an aromatase inhibitors on chick’s sex phenotype in order to produce more male birds which are economically beneficial to the broiler industry. In ovo injection of an aromatase inhibitor was carried out with 360 eggs of Ross 308 that randomly divided into six groups with 5 replicates. Experimental groups included: 50 (L50) and 100 (L100) µg of Letrozole, multivitamin + antibiotic (MA), antibiotic (A), male and female mixed control group (C1), and also male and female separated control group (C2). Hatched chicks were reared with the same diet and condition up to 42 days of age. Percentage of hatchability, hematological parameters, level of steroid hormones, bone strength, and biochemical composition in the progeny broiler chickens were evaluated. In ovo injection of Letrozole did not cause any significant effect on percentage of hatchability and the chicks’ hematological and serum biochemical parameters whereas notably resulted in increased percentage of male phenotype and their serum testosterone level, feed intake, and improved feed covvertion ratio in the broiler chicks (P<0.05). This study reveals that in ovo Letrozole administration results in a higher male phenotype of hatched broiler chicks and markedly improved feed conversion rate of the progenies without negative effects on their survival and hatchability.

An experiment was conducted to determine the optimal dietary level of wheat middlings for Arian commercial strain broilers. One thousand and fifty hundred Arian broiler chickens (a mixture of two sexes) were reared from 5 to 49 days old in a completely randomized design with 5 treatments, 10 replicates and 30 birds in each replicate. Experimental treatments included zero (control), 12.5, 25, 37.5 and 50% levels of wheat middlings in the diet. Wheat middlings reduced the feed cost per kilogram of live weight of broilers at 49 days of age; these reductions at levels of 37.5 and 50% were about 9 and 11%, respectively, and were significant compared to the control. The multi-attribute decision making (MADM) method was applied to determine the optimal level of wheat middlings in the diet. Based on the scoring obtained from this method, the group of birds receiving 37.5% of wheat middlings gained the highest score (72.92) and the groups receiving 25, 50, 12.5 and 0% wheat middlings were in the next ranks (72.58, 72.52, 63.98 and 17.41), respectively. In the end, the optimal level of dietary wheat middlings inclusion to achieve the highest management score obtained by the MADM method was determined to be 34.7%.

In this study, the effect of silymarin powder (SMP), nano-silymarin (NSM), and lecithinized silymarin (LSM) were considered on shell quality, carcass characteristics, some blood biochemical parameters, concentration of calcium, and phosphorus bone and iNOS gene expression in older laying hens. Materials and methods Seventy 80-weeks Lohmann LSL-Lite hens were allocated to 7 treatments with 10 replicates. Treatments included: 1) diet without silymarin (control), 2) daily intake of 100 mg SMP/kg body weight (BW), 3) daily intake of 200 mg SMP/kg BW, 4) daily intake of 100 mg NSM/kg BW, 5) daily intake of 200 mg NSM/kg BW, 6) daily intake of 100 mg LSM/kg BW, and 7) daily intake of 200 mg LSM/kg BW. The results indicated that all groups receiving silymarin showed an decrease in serum cholesterol content than the control (p <0.05) except those fed the SMP 100 diet. There were a decreases in iNOS gene expression in birds fed the NSM and LSM diets compared to control group (p < 0.05). Moreover, the effects of silymarin were more pronounced when converted to NSM or LSM and offered at the highest level (p <0.05). Overally, diet supplementation with 200 mg/kg BW of NSM or LSM to have been able to reduce blood lipids and iNOS gene expression.

If spermatogonial stem cells (SSCs) are transplanted into the testicles of lambs that do not have this type of cell, they begin to produce sperm in the testis of the recipient rams. The aim of this study was to prepare recipient lambs. For this purpose, heat treatments of 35, 45, 55 and 65 °C or water-ice treatment for 20, 40 and 60 minutes were used for three replicates with two days interval. The results showed that the condition of the testicles was normal at 45 °C, but the treatment at 55 °C caused infection in the seminiferous tubules and at 65 °C, the testicles were completely destroyed. The use of water-ice treatments did not change the appearance of the testes. Colony formation after extraction and culture of SSCs at 45 °C treatment and water-ice treatments were significantly reduced compared to the control (P <0.05). Also, the expression of c-myc, plzfand gfrl genes as specific SSC markers was significantly reduced in 45 °C and cold treatments compared with the control (P <0.05). Accordingly, for reducing the number of SSCs in lambs’ testicles, water ice or 45 °C treatments for 20 minutes can be used three times at intervals of two days.

This research was conducted to study the effect of chickpea straw and strawberry forage in the diet of fattening calves. Eighteen Simmental male calves with initial weight of 285.16±38.15 kg were used in a completely randomized design with three diets over a four-month fattening period. Three diets were adjusted based on 70% concentrate and 30% forage. The forage section in the control was 18% alfalfa and 12% wheat straw, the second treatment was 25% strawberry plant, 3% alfalfa and 2% wheat straw and the third treatment was 25% chickpea straw and 5% alfalfa. The digestibility of diets was determined by acid-insoluble ash method. The use of strawberry forage and chickpea straw had no effect on feed intake and performance of calves. The digestibility of dry matter and organic matter in diet containing chickpea straw was higher than other complete feed blocks, however, the digestibility of NDF and ADF was higher in diets containing chickpea straw and strawberry forage than control . The feed conversion ratio in the group receiving chickpea straw was better than the control group. The cost price per kilogram of complete feed containing strawberry forage and chickpea straw were 20.2 and 24.57% lower than the control, respectively, which resulted in a reduction in feed cost per kilogram of increased calf weight compared to the control group. The results of this experiment showed that the use of strawberry forage and chickpea straw as a forage portion up to 25% in the diet reduced the cost of calf fattening.