نشریه پژوهش های علوم دامی
سال بیست و یکم شماره 1 (بهار و تابستان 1390)

This experiment was conducted to evaluate the effects of different nutrients levels on performance and carcass traits of broilers during 1 to 49 days of age. For this purpose 384 days old Ross-308 broilers in a completely randomized design was used with 6 treatments in four replicates (n=16). The experimental diets were consisted: 1- NRC (1994) recommendation; 2- %110 of NRC recommendation; 3- Ross catalog recommendation; 4- %90 of Ross catalog recommendation; 5- nutrient level mean of NRC and Ross-308 catalog with recommended periods by NRC; 6- nutrient levels mean of NRC and Ross-308 catalog with recommended periods by Ross Catalog. All of the rations were isocaloric، with different levels of nutrients. The results of this study indicated that، in all of the periods، the body weight gain and feed intake in broilers fed by NRC recommendation significantly higher than other treatments (P< 0. 05). Decreasing of dietary nutrient levels to %90 of Ross catalog recommendation significantly decreased feed intake as compared to other treatments in all periods. The broilers were fed 110% of NRC nutrient levels had the lowest feed conversion ratio than those were fed other rations (P< 0. 05). Percentage of carcass and breast in broilers were fed by NRC nutrients levels were significantly higher than those were fed by other nutrients levels (P<0. 05). Using of NRC nutrients levels significantly decreased the production costs of each kilogram of live weight in comparison to other nutrients levels. These data suggest that formulation of diets based on NRC recommendation could be useful in improvement of performance and decreasing of production costs.

Effects of microwave irradiation (900 W، 2450 MHz) for 3، 5 and 7 min on nutritive value of barley and corn grains were evaluated using in vitro gas production technique. Gas production volumes were recorded at 2، 6، 12، 24، 48 and 72 h of incubation and then gas production kinetic was estimated. The obtained data from gas production at 24 h after incubation were used for estimation of metabolizable energy، net energy for lactation، short chain fatty acids، digestible organic matter and microbial protein. Irradiation of microwave increased (P<0. 05) gas production of barley grain after 24 h، but the differences between different irradiation times were not significant. This heat treatment resulted decreasing in gas production of corn grain after 6 h. The rate of gas production of barley (10. 01 % h-1) and corn grain (6. 56 % h-1) decreased by microwave irradiation. Microwave treatment increased (P<0. 05) gas production of soluble and insoluble fraction (A) of barley grain، but did not affect corn grain. Microwave heat treatment of corn grain significantly decreased (P<0. 05) values of metabolizable energy، net energy for lactation، short chain fatty acid، digestible organic matter and microbial protein، but in barley، this treatment increased significantly (P<0. 05) mentioned parameters. The rate of gas production of barley grain can be decreased by microwave irradiation resulting improved rumen ecosystem and decreased acidosis due to decreasing of rate of fermentation.

Present study was conducted to study the effects of poultry by-product meal (PBPM) on performance of commercial Laying Hens. 160 Hy–Line W-36 hens at the age of 42 wk were selected and housed in laying cages with four hens per cage. Five experimental diets containing 0%، 2%، 4%، 6% and 8% PBPM were formulated according to nutrient requirement recommendations of Hy-Line W-36 strain and were fed during 42-52 wk of age. The trial was conducted using completely randomized design with five experimental diets as treatments and four replications for each treatment. Tow cages served as one replication. Egg weight، egg production percent، egg mass and feed intake were significantly decreased as the level of PBPM was increased in the diets (P<0. 05). Feed conversion ratio was significantly increased by increasing the level of PBPM in the diets (P<0. 05). The highest Haugh unit (80. 38) and yolk color (7. 18) were observed in diet containing 8 percent PBPM (P<0. 05). Increasing level of PBPM in the diets had no significant effect on albumen and yolk percentage. The effect of different levels of PBPM on serum glucose، cholesterol، triglyceride، calcium، phosphorous، LDL and HDL concentration were not significant. The results suggested that this product could be used up to 2% in layer diets at the 42-52 weeks of age without any detrimental effects on laying performance، egg quality and blood parameters.

105 multiparous and 15 primiparous Holstein cows were assigned based on parity to three treatment groups: 1) six times milking a day for 150 DIM (6x); 2) six times daily milking for 90 DIM followed by three times daily milking (6x-3x); and 3) three times milking a day for 150 DIM (3x). Milk production was recorded every other day for the first 60 day and on two consecutive days in a week subsequently. Cows were weighed and scored for body condition immediately after parturition and monthly afterwards. Blood samples from tail vein and milk samples from all milking times in a day were taken monthly. Dry matter intake was not significantly affected by milking frequency treatment. Milk and 3. 5 % fat corrected milk production were higher in 6x and 6x-3x cows compared to 3x cows during experimental period (41. 03، 42. 13; 40. 11، 40. 60، respectively vs. 37. 97، 38. 40). Blood glucose concentration was significantly higher in 3x cows than 6x and 6x-3x cows (69. 02، 64. 36 and 63. 44، respectively) and blood NEFA and BHBA concentration were significantly lower in 3x cows than 6x and 6x-3x cows (0. 33، 0. 69; 0. 44، 0. 94 and 0. 38، 0. 91، respectively). Regarding production and economic aspects، milking six times daily for 90 DIM and 3 times subsequently was preferred to other treatments.

The genetic polymorphism of goat caseins has raised a considerable research interest due to its relationship with milk composition and technological characteristics important for cheese making. The goat milk also is important in human nutrition because of its quite different composition from bovine milk. In this study، the blood samples of 80 goats were collected from a herd kept in Sanandaj research station. After extraction of genomic DNA، two separate fragments of 407 and 279bp of goat kappa-casein gene located on exon four were amplified using specific primers and analyzed using PCR-SSCP and PCR-RFLP techniques، respectively. The 279-bp fragment had polymorphic restriction sites for HaeIII and TaqI endonucleases for alleles E and K، respectively but these alleles were not seen in this population. In the SSCP، 13 different alleles such as A، G، C''، J، M، C، H، B''، D/I/L and B''/B were identified. The allele A and B with frequencies of 0. 401 and 0. 018 were the most frequent and the lowest frequency respectively. The results of this research showed that combination of these two techniques can determine polymorphism presented in the studied population.

In order to evaluate the effect of feeding different levels of wheat bran on fattening performance as well as carcass characteristics، an experiment was conducted on fifteen Baluchi male lambs. The experiment was done using three treatments with five replicates each. in completely randomized design manner. The treatments consisting 10،20and 30% wheat bran. In the last two treatments، wheat bran was substitute with barley and corn. The experiment was run for 90 days. The results indicated that carcass componentsas well as، average daily gain، final live weight and feed conversion ratio were not affected by the treatments. Feed intake as well as nutrient consumption were not significantly affected by the treatments. Wheat bran consumption was affected by the treatments significantly (P<0. 05). Although pH was not significantly affected by the treatments، ammonia nitrogen concentration was different among the treatments (P<0. 05) and increased as wheat bran percentage increaded. It can be therefore concluded that levels higher than 30% DM of wheat bran could be used in replace of cereals.

This study was conducted in order to evaluate of premix included selenium and vitamin E effect on serum antioxidant (selenium، glutathione peroxidase and vitamin E) and F2 isoprostanes (marker of oxidants) on 40 Arabian male horses. Animals were located in control and treatment groups. Control group received only routine equine diet. Treatment group received routine diet plus premix (included 0. 5 mg sodium selenite + 250 mg α- tocopherol) for sixty days. Blood samples (5ml) were taken by venoject tube from jugular vein on day 0، 30 and 60 of trail period. Blood sera selenium، glutathione peroxidase، vitamin E and F2 isoprostanes concentrations were measured using atomic absorption، biochemical، fluorimetric chromatography and ELISA respectively. The mean of measured parameters did not show any considerable changes at study period (0 – 60 day) in control group،But sera F2 isoprostanes decreased and other metabolites increased significantly in treatment group. the mean of sera selenium، glutathione peroxidase، vitamin E and F2 isoprostanes concentrations had significant difference between control and treatment groups on 30 and 60 day. On day 30 the correlation of selenium and glutathione peroxidase was significant in both groups (P<0. 001 and r= 0. 961; P<0. 001 and r= 0. 844 respectively). the correlation of selenium and glutathione peroxidase was significant in control group (P<0. 001 and r= 0. 940)، but the correlation of selenium and glutathione peroxidase (P<0. 001 and r= 0. 727) and the correlation of selenium and F2 isoprostanes (P<0. 05 and r= - 0/530) was significant in treatment group at day60. The results of present study showed that use of vitamin E and selenium premix increased blood sera antioxidants and decrease F2 isoprostanes، according to results، use of premix is important in horse especially during exercise.

This experiment was carried out to study the effect of deactivation of sainfoin phenolic compounds using PEG (6000) and water on sainfoin digestibility، rumen and blood parameters of Holstein cows fed with sainfoin. This trial designed using 3 nonlactating ruminally cannulated multiparous Holstein cows، in balanced changeover design consisted of 3 diet and 3 periods of 17 days (10 days for adaptation and 7 days for sample collection). Extractable tannin content of control forage was 21. 3 (g/kg DM). Both of treatments were able to decrease it more than 90 percent. Treatments resulted in increased digestibility of organic matter، crude protein، forage cell wall and metabolisable energy of sainfoin (P<0. 05)، but no effects have been found on total concentrations and molar proportions of rumen volatile fatty acids. Tannin deactivation can cause elevation of ruminal ammonia nitrogen concentration (P<0. 05)، but blood urea، glucose and creatinine concentrations were not affected. Tannin deactivation increased DM degradability of sainfoin in PEG treated group (P<0. 05). We concluded that PEG and water treatments diminished phenolic compound in sainfoin and could elevation of nutrient availability، especially in the case of nitrogen. Water treatment was practical method for processing of sainfoin in Iran and can be used on the farm.

The growth parameters of Ross broiler chickens was estimated using Gomperz non-linear model in an experiment with different levels of grass pea seed. In this experiment 210 fourteen days old broilers were randomly assigned to 7 diets including 0، 10، 20 and 30% of raw or oven-heated grass pea seed with 3 replicates including 10 birds per each replicate by using completely randomized design. The results showed that according to the fitted model، the initial weight parameter (w0) was highest for treatments containing 20 and 30 % raw grass pea seed. The birds that received 20 % oven-heated and 30% raw grass pea seed، had significant differences about initial weight (w0)، final weight (wf) and the time of inflection point (t*) parameters. t* was predicted later (47 d) for diet containing 30 % raw grass pea seed than diet containing 10 % oven heated grass pea seed (39 d). There were significant differences (P<0. 05) between diet containing 30 % raw (2279. 4 g) and 10 % oven-heated grass pea seed (1701. 2 g) about body weight، at the t*. A lower initial weight and earlier growth change was revealed for chickens fed with diet containing 20 % oven-heated grass pea seed. Chickens fed with diet containing 30 % raw grass pea seed، showed not only later time but also greater weight at t* as compared to diet containing 20 % oven-heated grass pea seed.

To study calving interval and days open of Holstein cows in West and East Azerbaijan Provinces and the effects of some factors on them، 2213 records from ten herds collected during years 2000 to 2008 were used. The statistical analysis of data was done with proc. GLM (generalized linear models procedure) of SAS. The mean (±SE) of calving interval and days open were 395. 12±1. 36 and 115. 38±2. 98 days، respectively. Effects of herd، lactation number، year of calving and milk yield on calving interval were significant (P<0. 05). Effect of sex of calf on reproductive performance was not significant. Milk yield was increased from years 2000 to 2008. The relationship between milk yield and days open was not significant. It is important to give more emphasis on reproductive traits besides production traits to improve them in the herds of these two provinces.

In this research، the effect of environmental factors on 15507 records of production traits (milk yield، fat yield، fat percentage، protein yield and protein percentage) was studied. Data collected from 163 buffaloes herds from Guilan، Mazandaran، West Azerbaejan، Khuzestan and Ardebil provinces by Animal Breeding Organization of Iran during 16 years (1992-2008). The environmental factors were state، herd nested within state، lactation period، age at calving، season of calving and year of calving، analysed by GLM procedure in SAS software. Least square means and standard errors of milk yield، fat yield، fat percentage، protein yield and protein percentage were 1904. 16±6. 51kg، 123. 21±0. 46kg، 6. 41±0. 01%، 90. 65±0. 50kg، 4. 16±0. 01%، respectively. Result indicated that age at calving was significant for fat percentage only lactation period significantly influenced all traits، except fat percentage (P<0. 01). The effect of all other factors on all traits was significant.