فصلنامه تحقیقات تولیدات دامی
سال دهم شماره 4 (زمستان 1400)

This study aimed to investigate the effect of reducing the dietary level of crude protein (CP) and inclusion of extruded soybean meal (SBM) and canola meal (CM) on blood and ruminal parameters, the population of methanogens, and hyper-ammonia producing bacteria (HAB) of feedlot calves. To this purpose, 36 male calves were used in a completely randomized experimental design with six treatments and six replicates. Experimental treatments included: 1) Control (CP=15%, SBM (15SBM)), 2) SBM (CP=13%, 13SBM), 3) Extruded SBM (CP=13%, EXSBM), 4) CM (CP=13%, 13CM), 5) Extruded CM (CP=13%, EXCM), and 6) Fish meal (CP=13%, FM). Concentrations of albumin, total protein, creatinine, and blood urea nitrogen in experimental treatments decreased compared to 15SBM (P>0.05). The highest values of ruminal ammonia and acetate and the lowest amounts of propionate and volatile fatty acids (VFA) were observed in the 15SBM (P<0.05). The minimum ruminal HAB population was observed in EXSBM and EXCM and then in 13SBM, 13CM and FM and was maximum in 15SBM (P<0.05). Also, treatments fed EXSBM and EXCM had a smaller methanogens population than the control group (P<0.05). Based on the results obtained, decreasing dietary CP level and processing of extrusion for SBM and CM decreased HAB population, rumen ammonium, and blood urea concentration. Furthermore, extrusion declined methanogens bacteria population and acetate to propionate ratio and increased total VFA concentrations which can be considered as an indication of the rumen improvement in fermentation efficiency index.

In this research, an ozone gas-based oxidation technique for enhancement of delignification along with urea-based chemical treatment as a nitrogen source was used to improve the nutritional value of wheat straw. The experiments were performed with four treatments and three replications in a completely randomized design. Experimental treatments of wheat straw were 1. Untreated sample, 2. Separate treatment with urea (3% w/w, 24 h), 3. Separate treatment with ozone (3 g/h, 45 min), and 4. Combined treatment of ozone (3 g/h, 45 min) with urea (3% w/w, 24 h). The results showed that ozonized treatments had a significant improvement (P<0.01) in the nutritional value of wheat straw compared to the untreated and urea-treated samples. Also, According to the results, the combined ozone-urea treatment increased the nutritional value of wheat straw more than urea and ozone treatment alone. The combined ozone-urea treatment caused a reduction of 18.28%, 7.97%, and 50% in NDF, ADF, and ADL, respectively. Also, improving the nutritional value was observed by increasing 333.3%, 22.5%, 23.67%, and 35.34% in CP, bonded organic-N, TDN, and RFV, respectively, and improvement of gas production parameters were obtained by increasing 100.21%, 63.76%, 34.93%, and 46.43% for GP24, ME, IVOMD24, and SCFA, respectively, as compared to control sample. Overall, from the results of this study, it can be concluded that combined ozone-urea treatment is comparable to traditional and existing novel treatment methods, which due to its ability to perform at ambient temperature, atmospheric pressure, and short-time treatment, can be used as a suitable alternative in agricultural straw treatments.

To investigate the milk yield and composition and some blood parameters of pregnant ewes receiving a slow-release bolus of copper, 120 Lori-Bakhtiari pregnant ewes (in their third and fourth parities with a body condition score of 3 to 3.5) were divided into three groups of 40 heads each in a completely randomized design. Treatments included: 1) control ewes (5.79 mg copper per kg of dry matter); 2) ewes receiving two milligrams of copper per day (one bolus), and 3) ewes receiving four milligrams of copper per day (tow boluses). On the first day, days 10 and 60 postpartum, blood samples were taken from the ewes. Serum copper concentration, serum ceruloplasmin concentration, and white blood cell count were significantly higher in ewes receiving one or two copper bolus than in the control group (P<0.05). Milk production, protein content, and percentage of non-fat milk solids were significantly higher in ewes receiving two copper bolus than in other treatments (P<0.05). Also, ewes receiving one copper bolus had significantly higher milk production, protein content, and percentage of non-fat milk solids than the control treatment (P<0.05). The percentage of milk fat in the control group was higher than ewes receiving two slow-release copper bolus (P<0.05). Milk copper concentration in ewes receiving one or two copper boluses was higher than in the control treatment (P<0.05). In general, both levels of copper improved milk production and some blood parameters, but the use of two boluses is recommended for higher milk production.

In this study, the effect of black cumin and the black seed was evaluated on the growth, blood metabolites, thyroid hormones, and liver enzymes activity of lambs under pasture grazing conditions.  Twenty-four Sanjabi male lambs in their four to five months of age (live weight of 30 ±0.9 kg) were used in four treatments and six replicates in a completely randomized design for 70 days. Treatments included group 1: Control (rangeland forage), group 2: Rangeland forage plus 0.3 g of black seed per kg body weight (BW), group 3: Rangeland forage plus 0.3 g of black cumin per kg BW, and group 4: Rangeland grass plus 0.15 g of black seed + 0.15 g of black cumin per kg BW. The lambs were weighed every two weeks. Blood samples were collected from the jugular vein on days one, 35, and 70 of the experiment. Adding black seed and cumin had no significant effect on growth performance, but significantly increased total blood protein in treated groups (P<0.05). The blood urea level of lambs in treated lambs was lower than in the control group. Thyroxine concentration in lambs fed on black seed was higher than that of other groups (P<0.05). The activity of aspartate aminotransferase and alanine aminotransferase was lower in the herbal supplemented groups than in the control group (P<0.05). Overall, the results of this experiment showed that incorporation of these amounts of black seed and black cumin to the diet as herbal supplements improved some blood parameters, but had no significant effect on growth performance.

The main aim of the present research was the genetic analysis of the first lactation milk yield trait and evaluation of the impact of selection for milk on the phenotype of age at first calving in Iranian dairy cows using quantile regression. Lactation milk records of 327190 first parity cows (progeny of 5260 sires and 235172 dams) in 637 herds (in 15 provinces) and calved between 2007 and 2015 were utilized. Genetic analysis was carried out with the use of an animal model. In the model, fixed effects of the province, herd, year and month of calving, covariates of lactation length, age at first calving, percentage of Holstein gene, as well as the random effect of the cow were included. The model was fitted on the data using the DMU package. Regression of age at first calving on predicted breeding value was fitted through a quantile regression model. The findings revealed that the heritability of lactation milk yield was equal to 0.276. Annual genetic gain in grade and Holstein purebred were found to be 17.352 (R2=0.913) and 23.398 (R2=0.962) Kg, respectively (P<0.0001). All estimated regression coefficients were negative in different percentiles of age at first calving and ranged between -0.0009 and -0.0344 (month per Kg) which indicates that the influence of genetic potential of cows for milk yield on different parts of calving age distribution is not the same.

The present study aimed to determine the best mathematical model to describe the growth curve of dromedary camels. For this purpose, the data recorded between 1990 and 2018 in the National Research and Development Station on Dromedary Camel located in Bafgh, Yazd province, were used. The records included the body weight of 747 dromedary camels at different ages (from birth to 14 months of age). To determine the best model describing the growth curve of dromedary camels, eight different mathematical models including linear, quadratic, cubic, Gompertz, Brody, logistic, monomolecular, and von Bertalanfy were compared. The age of camels was included in the model as an independent variable and the weight of camels as a dependent variable. The criteria for comparing the performance of the models were having the highest value of the corrected coefficient of determination (R2 adj) or the lowest values of Akaike information criterion (AIC) and the mean square error (MSE). Based on the results of this study, the accuracy of linear, quadratic, and cubic equations in describing the growth curve of dromedary camels was significantly lower than that of Gompertz, logistic, monomolecular, von Bertalanfy and Brody models. The results of the present study showed that the weight of dromedary camels could be predicted precisely up to weaning age (200 days), However, after weaning, due to the effect of different environmental conditions on the growth of camels and a sudden change in feed type, the increase in camel weight does not have a linear relationship with their age, and it is better to use other parameters such as biometric measurements to accurately estimate camel weight.

The objective of this study was to investigate the effect of two processing methods of barley and corn grains (steam-flaking or cracking) and the addition of a probiotic containing Enterococcus faecium (10 g/d to provide 2.5 × 1011 colony-forming unit) to diet on nutrients digestibility, fecal pH, blood glucose, and pathologic problems of horses. In this experiment, 12 adult Kurdish horses with an average weight of 416± 43 kg were used in a replicated 4×4 Latin Square experiment with a 2×2 factorial design during four periods of 28 days, including 21 days for dietary adaptation and seven days for sampling. Experimental diets (60:40 forage to concentrate ratio) were: 1) Cracked grains based diet without probiotic, 2) Cracked grains based diet with 10 g/d probiotics, 3) Steam-flaked grains based diet without probiotic, 4) Steam-flaked grains based diet with 10 g/d probiotics. Results showed that mean fecal pH was 6.57 in different treatments and was not affected by the type of grain processing, probiotic supplementation, and their interaction (P>0.05). Also, digestibility of dry matter, organic matter, NDF, and ADF, as well as blood glucose, lameness, and colitis incidence were not affected by two types of cereal processing including cracking or steam-flaking, the addition of probiotic, and their interaction. Overall, our results showed that replacing steam-flaked corn for cracked corn and supplementing 10 g per day enterococcus faecium probiotic did not affect digestibility, fecal pH, and blood glucose. However, further research is recommended to investigate the effects of higher enterococcus faecium probiotic doses in high grain diets.

To evaluate the effect of hydroalcoholic extract of Scrophularia striata (SSE), vitamin E, vitamin C, and selenium on performance, blood parameters, and immune response of broilers under heat stress conditions, an experiment was performed using 350 one-day-old male broilers (Ross 308) in a completely randomized design with seven treatments and five replicates (10 chickens per replicate). Experimental groups were a group under normal environmental conditions (negative control), a group under heat stress (positive control), and other groups under heat stress and fed with the diet supplemented with 200 ppm vitamin E, 500 ppm vitamin C, 0.3 ppm selenium, or 200 and 400 ppm SSE. From day 1 to the end of the breeding period, a temperature of 34 ± 2 °C was applied to create heat stress for 8 h (10 am to 6 pm). The results showed that all treatments improved (P<0.05) body weight gain, feed conversion ratio, performance index, heterophil to lymphocyte ratio, total and IgG titers against sheep red blood cells, and cellular immunity (toe web swelling skin in response to phytohemagglutinin injection), and the best performance was observed in the negative control, high SSE and vitamin E, respectively. All experimental treatments, except for low SSE and selenium treatments, increased blood lymphocytes and potassium compared to the positive treatment (P<0.05). In general, the inclusion of 400 ppm of SSE in the diet had a beneficial effect on growth performance, blood parameters, and immune response during heat stress.

The present descriptive-survey research was conducted to investigate attitudes of fatteners about the factors affecting the development of male calf fattening units in Guilan province. The data of the present study were collected through a questionnaire and its validity was controlled by 10 professors and its reliability was obtained by calculating the Cronbach's coefficient of 0.92. The study population of fatteners included 52 active fattening units in Guilan province which were census. This research was conducted in two separate sections. The purpose of the first part was to be aware of the current situation of fattening in the province that the results showed that the average technical efficiency using the variable and constant efficiency approach to the scale is equal to 0.961 and 0.941, respectively, which show the high production efficiency of fattening units in Guilan province and also fatteners' satisfaction with continuing their work was moderate. The second part of the study sought to examine the attitude of fatteners about the factors affecting the development of male calf fattening units in Guilan province, which examined the attitude of fatteners about social, economic, fattening cooperatives, structure, and presentation of educational-extension courses. The results showed that from the point of view of fatteners, indicators of economic, structural, and participation in educational-extension courses have a significant impact on fattening and explain about 95% of its changes.