مجله علوم دامی ایران
سال پنجاه و یکم شماره 1 (بهار 1399)

The aim of present study was to produce selenium enriched yeast and determine its optimum level on morphology and biometry of internal and reproductive organs in broiler breeder hens in comparison to Selemax (commercial organic sodium selenite) and mineral selenite. This study was done in two parts, in the 1st experiment; selenium-enriched yeast was produced. In the 2nd experiment, a total of 150 Ross 308 broiler breeder hens (49 weeks of age) were used in 6 treatments of 5 replicates with 5 hens each. The treatments were included: 1) Control group (without selenium), diet containing; 2) 0.15; 3) 0.30 and 4) 0.45 mg/kg of produced selenium enriched yeast (SY0.15, SY0.3, SY0.45, respectively), 5) 0.30 mg/kg Selemax, and 6) 0.30 mg/kg sodium selenite (SS). At the end of the experiment, three hens from each replication were slaughtered. In the 1st experiment, the amount of selenium per kilogram of dry selenium-enriched yeast was 2823 mg. In the 2nd experiment, the number of large follicles in the SY0.45 group was significant higher compared to control, SY0.15 and SS groups. The weight of the abdominal cavity fat of the SY0.45 group was significantly lower compared to control group. Therefore, using of 0.45 mg/kg of produced organic selenium in the broiler breeder diet increased number of large follicles and decreased abdominal cavity fat. Of course, further studies are needed to assessment of other performance and reproductive parameters.

A multiple-component pricing (MCP) method for the purchase of milk by dairy processors in Iran was developed and compared with the current procedure, reference on percentage differential pricing (PDP) method. Data on the quantity and quality of raw milk and dairy products, and economic data relating to the sale prices of dairy products and processing costs for the Iran dairy market in 2017 were used. Cheese, cream, skim milk powder and liquid milk were the reference dairy products. After calculation of net return for each reference product, and consideration of composition and total production share, economic importance for milk fat and protein were estimated using weighted least square method. Economic values for each percent of milk fat and protein were estimated as IRR 2,741 and 1,311 respectively, with a total value of 12,704 IRR for 1 kg of basal milk (3.2% fat, 3.0% protein); this was slightly higher than the current PDP of 12,500 IRR. The effect of including milk composition (quality factors) in the MCP created a differential between milk of the highest and lowest quality that was more than twice that of using the PDP. This illustrates the importance of encouraging the adoption of MCP for dairy processors and farmers in Iran to take into account the pricing structure of the end-products. A more realistic pricing structure for milk based on the protein and fat content would encourage comparison of the value of different products (e.g. milk products vs. meat) for Iranian consumers.

The aim of the current study was to estimate the genetic parameters of growth traits at the late ages (25-45 days of old) as well as humoral immune responses in Japanese quail. Therefore, the studied traits were growth traits (body weights (BW) at 25, 30, 35, 40 and 45 days of age, average daily gain (ADG) in 5 day periods as well as the immune system responses against SRBC (IgT) and Newcastle vaccine (IgN)). To estimate genetic parameters, a multivariate analysis was utilized using Gibbs sampling through Gibbsf90 software. The heritability for BW and ADG were varied between 0.303-0.437 and 0.053-0.338, respectively. Moreover, heritability estimates for IgT and IgN were 0.252 and 0.015, respectively. Genetic correlation between growth traits with immune responses were negative and ranged from low to moderate (−0.218 to −0.483). According to the results, genetic selection based on BWs might to result in higher genetic response than ADG and immune system performances. Among body weight traits, the BW30 based on its higher genetic correlation with BW45 (0.809), moderate heritability (0.406) and negative and relatively low genetic correlation with IgT (−0.226) and IgN (−0.235) would be consider as an appropriate criterion introduce applicable breeding program to improve growth traits with lower decreasing in the immune system performance.

A total of 384 Shaver laying hens were selected at 50 weeks of age, and used in a factorial arrangement with two feed forms (mash and pellet) and three cage densities (3, 4 and 5 hens per cage) for 10 weeks. During 10 weeks of experiment, laying performance and at week 10 egg quality parameters, were measured. The results showed that hens fed pellet feed had higher egg weight at first 5 weeks and higher egg weight and lower feed intake and lower feed conversion ratio for ovearll 10 weeks of experiment, compared to those fed mash diet. During first 5 weeks of experiment, with increasing birds per cage 3 to 4 and 5, feed intake and feed conversion ratio (P<0.01), and for overall 10 weeks of experiment, with increasing birds from 3 to 5 per cage, egg production and feed consumption werer significantly reduced (P<0.05). The final body weight and weight changes of lying hens were affected by the cage density, feed form (P<0.01) and their interaction (P<0.05) during experimental period. The effect of cage density on shell thickness and specific gravity of eggs was significant (P<0.05). Egg production during the day was postponed in birds fed pellet feed or reared at higher density. The results showed that by increasing the cage density, laying performance was decreased, but for hens fed pellet feed, cage density had no effect on feed intake.

This study was designed to evaluate the effects of encapsulated reduced glutathione added to extender on the quality of bull sperm after freezing and thawing process. Extender contains lecithin nanoliposomes supplemented with different concentrations of glutathione (0, 1, 2.5 and 5 Mm concentration). The supplemented nanoliposomes with glutathione were prepared by thin-film preparation method.  The particle size decreased to nanometer by sonication. 40 ejaculations were collected from 6 Holstein bulls and frozen for 6 weeks. Evaluated characteristics after freezing and thawing process were kinetic parameters (CASA), membrane activity (HOST), membrane integrity (eosin-nigrosin) and morphology of sperm ( Hancock's solution). Results showed that level 1 mM significantly increased the total and progressive motility (47.5±1.7, 32.7±2 %).  Although, there was no significant difference with level 2.5 mM glutathione (45.0±1.7, 26.2±2 %). Also, the concentration of 2.5 mM showed the highest value of cell membrane integrity and cell membrane functionality but did not differ with the concentration of 1mM. However, supplementation of nanoliposomes with 5 mM glutathione reduced the quality of post-thaw sperm. Thus, level 1 M encapsulated glutathione can provide better protection compare to the other level of that for bull sperm.

In the present study, data collected from 1993 to 2011 in Raeini Cashmere goat breeding station were used for genetic evaluation and inferring causal relationships among reproductive traits applying structural equation models. The studied lifetime reproductive traits were included the overall number of kids born (OLSB), the overall number of kids weaned (OLSW), the overall litter weight at birth (OLWB) and the overall litter weight at weaning (OLWW). Three models including standard (SMM), recursive based on prior knowledge (PRM) and recursive based on inductive causation algorithm (ICM) multivariate models were used for genetic evaluation of animals under the Bayesian approach. The comparisons of the investigated models via deviance information criterion (DIC), mean square error (MSE) and Pearson's correlations between observed and predicted records () revealed that ICM had lower DIC and MSE and higher () for all the studied lifetime reproductive traits; implying the more plausibility of ICM over SMM and PRM. Furthermore, re-raking of the animals under SMM and ICM confirmed the importance of considering the causal relationship among the traits for ensuring accurate ranking of animals according to their breeding values.

This study intended to investigate the effects of canola meal fermentation on its nutritional characteristics and broiler chickens growth performance using Lactobacillus fermentum and Bacillus subtilis and Aspergillus oryzae. In this experiment, 280 male Ross day-old chicks were randomly assigned to 7 experimental treatments with 4 replicates containing 10 chicks each. Treatments included control diet, canola meal and fermented canola meal at 3 levels (5, 10 and 15%) each. Results indicated that fermentation of canola meal reduced the amount of glucosinolates and amino acids methionine and cysteine by 50%, while its sulfur content increased about 50% and protein content of fermented canola meal increased by 2.2%. At the level of 15%, processed and unprocessed canola meal had no effect on growth performance, weight of carcass parts, tibia mineralization and nutrient digestibility in grower, finisher and whole period .It is concluded that fermented canola meal increased TSH and ACTH levels. Also intestinal viscosity increased with consumption of both types of meal (P <0.05) but had no effect on jejunal morphology and ileum pH. canola meal meal (processed or unprocessed) can be used up to 15% in broiler diets without any adverse effect. However fermentation process reduces the glucoseinolate level significantly.

The present experiment was designed to evaluate the efficiency of the slow-release bolus containing different selenium levels on performance and some blood and milk parameters of Lori Bakhtiari ewes. For this purpose, 45 ewes were divided into three groups (15 in each). Treatments were: 1) control ewes; 2) ewes receiving 0.2 milligrams of selenium per day; and 3) ewes receiving 0.4 mg selenium per day. On the first day of the experiment, all ewes received CIDR and the boluses were fed to the different groups on the same day. During the feeding period the ewes were grazed on the pasture. Blood samples collected from all ewes at 76 days post-mating (mid-gestation) and 30 days postpartum before going to rangeland. The results showed that birth weight, weight at two months of age, average daily gain, milk production, fat content, protein content, non-fat solids content in milk and milk selenium concentration were higher in the groups receiving selenium than the control (P<0.05). Milk production of ewes receiving 0.4 mg selenium per day was higher than those of receiving 0.2 mg selenium per day (P <0.05). Serum selenium and triiodothyronine concentration and blood glutathione peroxidase activity in ewes receiving different levels of selenium were higher than those of control (P<0.05). Overall, both levels of selenium improved the performance of the lambs and some of the blood and milk parameters of the ewes, but the use of 0.40 mg Se/day due to higher milk production is recommended.