مجله تولیدات دامی
سال دوازدهم شماره 2 (پاییز 1389)

Mulberry powdery mildew is the most important fungal disease in silkworm rearing zones. Resistance of mulberry varieties is different against this disease. The mulberry varieties have different resistance against powdery mildew disease. Percentage of moisture, nitrogen, protein, phosphor, fiber, calcium and ash of powdery mildew infected leaves and healthy control in five mulberry varieties including Kenmochi, Local, Kaironozomi, Ichinose and Shinichinose were determined. Meanwhile, larvae mortality percentage, pupae mortality percentage, total produced cocoon weight, cocoon weight, single cocoon shell weight and percentage, and produced cocoon number recorded after larvae feeding with control and infected leaves. The obtained results showed that powdery mildew disease resulted to nutrients decline in mulberry leaves and economical parameters in those larvae which fed with infected leaves (P< 0.01). Moisture percentage, protein, percentage, nitrogen, phosphor, calcium decreased after powdery mildew infectious for each five races. Meanwhile, pupae mortality percentage, single cocoon weight, single cocoon shell weight and percentage, and produced cocoon number decreased after feeding with infected leaves for total five varieties significantly (P< 0.05). Therefore, quality decline of mulberry leaf under powdery mildew disease resulted to decreasing of silkworm performance in rearing process.

In this study, the effect of different levels of fat with antibiotics and probiotics on blood biochemical traits and performance of broiler chicks was investigated. In a factorial experiment, 288 Day-old Ross broiler chicks treated with two level of fat (3 and 6 percent) and three additives (Flavomycin, Protexin and none-additive). The birds were allocated randomly in six treatments with four replicates and 12 birds per replicat. Results showed that the chicks fed on diets containing 3 percent of fat + Flavomycin had higher feed intake and body weight gain compared to birds fed with fat + Protexin (p< 0.05). The concentration of cholesterol, HDL and LDL in serum of birds of 6% fat was more than of those fed diets with 3% fat. Birds fed diets containing protexin had lowest cholesterol, HDL and LDL (p< 0.05). It was concluded that supplementing the rations containing fat with probiotics decrease feed intake and body weight gain in broilers chicks and their performance decrease by increasing fat in diets.

In this study, the genetic and phenotypic trend of milk and fat production traits were estimated form 94121 cows’ first lactation records and that for age at first calving and calving interval traits were estimated from 41900 cows’ reproduction records. Data related to Iranian Holstein dairy cattle from 1995 to 2003. Data were analyzed, using univariate and mulitivariate animal model with genetic group effects. The heritability of milk yield, fat yield and fat percentage, age at first calving and calving interval were 0.29 (±0.01), 0.22 (±0.01), 0.38 (±0.01), 0.055 (±0.01) and 0.034 (±0.005), respectively. The linear regression of average breeding values and phenotypic values of cows for a trait on birth year provided an estimate of genetic and phenotypic trend, respectively. There genetic trend for milk yield, fat yield and Calving Interval were 53.5 kg, 1.07kg and 0.46 day, respectively. Their trend for fat percentage and Age at First Calving were -0.011% and -0.23 day, respectively. There was a positive phenotypic trend for milk yield, fat yield and fat percentage. This trend was negative for Age at First Calving and Calving Interval.

To study of environmental effects (sex and age) on fleece traits of dromedary camel in Sistan and Balouchestan province, 48 male and female which rose in five cities (Zahedan, Zabol, Khash, Iran-shahr and Ghabahar) belonging to three age groups (<2, 2-6 and >7 years) were measured. Results indicated that there was not significantly different between sexes and age groups for all of fleece parameters, expect staple length of hump was effect by sex and also rump staple length and scoured yield were effect by age groups (P< 0.05). The means of shoulder, flank, rump, hump and overall four spots staple lengths were 4 (± 1.6), 2.6 (± 1.2), 2.6 (± 1.4), 4.4 (± 1.9) and 3.5 (± 0.13) cm. The means of inner coat, fiber diameter and coefficient of variation of fiber diameter, and scoured yield were 82 (± 1.07)%, 36.7 (± 1) micron, 38.8 (± 0.9)% and 74.3 (± 0.09)% res. The ranges varied of these characters were from 58.3 to 94%, 16.8 to 39.2 micron, 26.1 to 61% and 61.2 to 84.5%, respectively.

The effect of feeding of soaked barley straw on milk production and composition and rumen characteristics was studied. The degradability of soaked barley straw (for 24, 48 and 72 hours) and unsoaked barley straws were studied in the first experiment. The unsoaked barley straw had more readily degraded fraction (a) than soaked straw treatments (p> 0.05). There was no significant difference between slowly degradable fractions (b) and degradation rates (c, %h) in various treatments of barley straw. The degradability parameters of different rations also studied. The differences between readily (a) and slowly (b) degradable fractions were not significant. In the second experiment the effect of partial replacement of alfalfa hay with unsoaked barley straw and 24h soaked barley straw on performance of 9 multiparous lactating dairy cows in midlactation (580.9 ± 39.3 BW) with 27.8 ± 4.5 kg daily milk yield was studied in a crossover design. The effects of different treatments on milk yield (p< 0.05), milk fat (g/kg yield) (p< 0.05), N-NH3 rumen liquor (p< 0.0001), rumination and chewing activity (min/d) were significant. The rumination and chewing activity (min/d) were increased in diets that contained barley straw. In conclusion utilization of soaked barley straw in ration of midlactation cows is recommended.

15 Holstein cows (1st lactation, 554 ± 57 Kg) randomly divided into three groups. Cows fed Vicia ervilia seed at the rate of 0%, 7% and 14%, DM of dietary, which replaced with Soya been meal and barely. Vicia ervilia (VE) contain approximately: 93.93% DM, 22.8% CP, 5.95% Ash, 3.02% EE, 63% NFE, 5.23% CF, 15.01% NDF and 6.13% ADF. The effective ruminal degradability of CP and DM of VE amounted to 74.76% and 70.57% respectively. Milk production increased in 14% group compared with control (P< 0.05). The values of urea nitrogen in treated cows were significantly increased (P< 0.05). The result of this study indicated that the Vicia ervilia can be used as a protein source replaced with Soya been at the 14% level in dairy cows ration during lactation period after partition.

Beta-lactoglobulin (LGB) is one of the proteins in the mammals’ milk synthesized by the epithelial cells of the mammary glands and affects the quality and coagulation of the milk. The aim of this study was to determine allele frequencies in LGB gene of Native and Holstein cattle in Kerman province using PCR-RFLP method. Genetic polymorphism, for 100 DNA samples in the locus was determined by digestion of PCR products with endonuclease HaeIII (LGB), followed by electrophoresis in agarose gel stained with ethidium bromide. Allele frequency for the A and B alleles in Holstein cattle was 0.62 and 0.38 and in Native cattle was 0.55 and 0.45, respectively. Average heterozygosity in Holstein and Native cattle was 0.47 and 0.46, respectively. Results indicated that the studied populations were not in Hardy-Weinberg equilibrium for the LGB locus.