فصلنامه تحقیقات تولیدات دامی
سال دوم شماره 3 (پاییز 1392)

In this study, production, reproduction, population, management and economic parameters resulted from recording of 12 industrial dairy farms in Chaharmahal-va-Bakhtiari province with herd size 20 to 250 and a total of 1240 head of Holstein cows in a cycle of production, during 2010 to 2012 were used for cost-benefit analysis and determination of the economical and biological efficiency values. Revenue was derived from milk, live weight, breeding animals and cull animals. Costs were included to feed, management and labor, health and veterinary, fuel and energy, interest rate and fixed. The results showed that the annually average profits per cow were ranged from 15206843 to 25921834 Rials (507 to 864 US$), revenue to cost ratio were 1.18 to 1.27 and biological efficiency ranged from 57.43 to 65.38 and all of them increased by milk production level. In general, the sale of milk yield, animal live weight and stock animal accounted the highest proportion of total revenue, respectively and the proportion of milk yield from total revenue increase by increasing milk level. The cost of feeding, interest rate, management and labor, health and veterinary, fixed and energy had the highest percent of total cost, respectively and the proportion of feeding cost increased with level of milk yield. The estimated cost- benefit analysis and efficiencies obtained in this study could be used to assist researchers, macro policy makers, determination of dairy cattle strategy and farmers in making decisions that will improve sustainability and also farm profitability.

The objective of this study was to determine the optimum number of young bull for progeny test program in Iranian Holstein dairy cattle population with the use of deterministic simulation. Three traits including milk yield, fat and protein yield were considered as selection goal traits. In the simulated programs, number of young bulls were variable, but number of daughters per young bull was kept constant equal to 70 heads so, selection accuracy was constant, but selection intensity was different. The economic efficiency of each progeny test program was considered as the ratio of discounted return to the discounted cost. Maximum economic efficiency, genetic economic gain, discounted cost and discounted return were equal to 5.46, 416223.75, 7307144667 (Rials) and 19766307238 (Rials), respectively, which were achieved by progeny testing of 29, 93, 120 and 100 young bulls. The study of optimum progeny test economic efficiency and the young bull number per %20 changes in model’s economic parameters showed that economic efficiency had the maximum sensitivity to changes in discounted rate and milk yield economic value. %20 fluctuations in discount rate and %20 decrease in young bull purchasing and maintenance cost were led to change in progeny test structure while %20 fluctuations in other economic parameters had no effect on the structure of optimum progeny test structure.

(Co) variance components and genetic parameters for growth traits including birth weight (BW), weaning weight (WW) and six-month weight (6MW) as well as parameters, genetic and phenotypic trends of reproductive traits including total weight of lambs weaned per the ewe (TWLW) and the number of lambs born at birth per ewe (NLBE) in Lori sheep were estimated using the Bayesian method. The data included 7363 records for BW, 7054 records for WW, 6765 records for 6MW, 1012 records for TWLW and 1048 records for NLBE. The data were collected by the Agricultural Organization of Lorestan Province between the 2001 to 2010 years (for growth traits) and 2003 to 2010 years (for reproductive traits). The estimates of direct heritability for lamb body weights were 0.36 at birth, 0.11 at weaning and 0.05 at six months of age. The genetic and phenotypic trends reproductive traits were calculated based on regression of the mean of breeding value on birth year and mean of phenotypic value on birth year, respectively. Heritability, genetic and phenotypic trends for TWLW trait were 0.05, 5.4±1.16 and 255±0.45 grams per year, respectively. Heritability, genetic and phenotypic trends of NLBE trait were 0.09, 0.002±0.02 and 0.125±0.07, respectively. Genetic improvement of TWLW and NLBE traits at considered period were 31.64 grams and 0.008 of Lamb. The estimate of heritability at birth was higher than other traits so selection based on this trait would increase the genetic advances. Genetic and phenotypic trends for reproductive traits were not significant and the genetic trend was low.

In order to investigate the effect of edible mushroom and savory on performance and nutrients apparent digestibility and humoral immune responses 120 one-day old Japanese quail chick were used in a completely randomized design, with 6 experimental treatments, 4 replications and 5 chicks per replicate. Rearing period lasted for 5 weeks. Experimental groups were: control (with no additives), antibiotic virginiamycin (15 ppm), edible mushroom and savory, each one in 2 levels (10 and 20 g/kg). Production indices were measured weekly and were reported for entire period. In order to study the humoral immune response, 0.2 ml of Sheep Red Blood Cell (SRBC) suspension was injected on day 28 of age and antibody titers were determined by hemaglutination assay on day 35. Also Newcastle vaccine B1 was used on day 21 for all birds and antibody titers were measured 2 weeks after vaccination. In order to measure the apparent digestibility of feed nutrients, 2 g of TiO2 per kg of feed, as an exotic marker, was used. Results showed that final body weight and body weight gain were not affected significantly by experimental treatments (P>0.05). Usage of 1% edible mushroom in diet and 1 (661.1 g) and 2% (589.9 g) of savory increased feed intake in comparison with control group (P<0.05). Nutrient apparent digestibility was not affected by experimental treatments (P>0.05). Based on the results of this experiment, supplementation of Japanese quail’s feed with 1 and 2% of edible mushroom and savory had no positive effect on performance and feed apparent digestibility, but 2% of edible mushroom increased antibody titers against SRBC in comparison with antibiotic and control groups.

This experiment was conducted to evaluate the effects of different levels of dietary crude protein (CP) on reproductive performance of native hens at Khorasan stations using 300 hens, in a completely randomized design with 6 dietary treatments and 5 replicates and 10 hens in each replicate from 26 to 50 weeks of age. Treatments based on corn, soybean meal and wheat with different levels of protein, including 17.5, 16, 14.5, 13, 11.5, and 10% CP levels and another nutrient including the energy was equal as possible. Results showed that the initial weight of chickens and the ratio of chicken weight to egg weight increased with CP levels upto 16% from the beginning of experimental period to 50 weeks and decreased with 17.5% CP level. The highest hatchability percentage in all periods was related to the 17.5% CP diet that showed significant difference with other treatments (P<0/05). Results on immune responses showed that treatment with 17.5 % CP, the highest titer of antibody against SRBC, IgG and IgM (P<0/05). In relation to cellular immunity (Test CBH) the result was slightly different and the highest cellular immune response to treatments containing 16% CP and higher levels of CP (17.5%) education compared to the treatment (16%). Overall, the results showed that reproductive performance and humoral immune response of native birds improved with increasing levels of CP.

The effects of different levels of Silymarin were studied on performance and immune responses in 288 one-day chicks (Cobb 500) in a completely randomized design with 6 treatments and 4 replicates and 12 observations per replicate. The treatment groups received 0 (Control), 160, 200, 240, 280 and 320 ppm of Silymarin in diet, respectively during days 3 to 42. Daily feed intake, daily body weight gain and feed conversion ratio (performance) were measured. The birds were immunized with sheep red blood cells (SRBC) on days 8 and 22 of age and serum antibody levels produced in response to SRBC were measured on days 21, 28, 35 and 42 by hemagglutination assay. Skin response to phytohemagglutinin-P (PHA-P) injected intradermally on day 16 were measured 24 and 48 h after injection. The results indicated that consumption of 200, 240, 280 and 320 ppm Silymarin reduced feed intake and feed conversion rate (P<0.05), but they did not affect on daily weight gain (P>0.05). The levels of 200, 240, 280 and 320 ppm Silymarin were increased total Anti-SRBC and IgG titer in experimental groups compared to control group (P<0.05), but IgM titer and skin response against PHA-P were not affected by Silymarin (P>0.05). It is concluded that the continuum consumption of 200, 240, 280 and 320 ppm Silymarin improved performance and increased humoral immunity in broilers.

Eexperiment was conducted to investigate the effects of a synbiotic containing Enterococcus faecium and inulin on performance, serum lipid and humoral immune response against sheep red blood cell (SRBC) with using 400 one-day-old male broiler chicks. Broiler chicks were randomly divided into 16 experimental units (25 birds per unit) and fed corn-soybean meal-based diets. Four units were considered for each treatment and 0, 0.5, 1 and 1.5 g/kg synbiotic supplement were added to diet for each treatment. The results showed that body weight gain and feed conversion ratio during the whole experimental period were higher in treatments 1 (2662g and 1.72, respectively) and 1.5 (2596 g and 1.74, respectively) g/kg synbiotic compared to control (P<0.05). Also, on 28 and 42 d, serum cholesterol levels were lower in treatments 1 (156.8 and 107.6 mg/dL, respectively) and 1.5 (146.3 and 106.5 mg/dL, respectively) g/kg synbiotic compared to control (P<0.05). On 41 d, the antibody titer against SRBC was higher in treatments 2 (8.09) and 1.5 (8.69) g/kg synbiotic in comparison with control (P<0.05). In general, the results of this experiment showed that using of 1 and 1.5 g/kg synbiotic in broiler diets could improve growth performance, immune responses and reduce serum of blood cholestrol.