مجله پژوهش در نشخوار کنندگان
سال یکم شماره 1 (بهار 1392)

The present study was carried out to estimate genetic and phenotypic parameters for litter size trait in Mehrabani sheep by threshold model. Data file included the litter size of 5069 ewes which collected from 1994 to 2010 at Mehrabani sheep breeding center under supervision of Agriculture-Jahad Organization of Hamedan. The pedigree file consisted of the information of animals burned which were born from 1987 to 2010. The number of lambs per ewe were used as, repeated records. The effects of herd, year, and lambing time were fitted in the model as fixed effects. The significance of fixed effects was examined using Logistic procedure of SAS software. The analysis for trait was carried out, using the Thrgibbs1f90 program. Estimates of direct heritability, maternal heritability and repeatability were 0.039, 0.11 and 0.057, respectively. The low estimations of direct heritability, maternal heritability and repeatability were obtained in the current study for litter size trait. It indicates that selection based on the ewe’s own performance may result in slow genetic improvement.

This study was conducted to estimate genetic parameters of milk production in Yazd Holstein dairy cows using fixed and random regression model. The dataset consisted of 35178 test day records belonging to 5101 first calving Holstein cows with two or three times of milking was used. Data were collected from 42 herds during 1991 to 2009. A combination of herd, year, season and times of milking were included in the models. Age at calving along with Holstein percertage of each cow were considened as covariates. Direct genetic and permanent enviromental effects were included in the models as random effects. Random direct genetic and permanent enviromental effects were fitted on milk production curve using Legender orthogonal polynomial with power three for permanent enviroment effect and power four for direct genetic effect in random regression model. Estimated heritability for milk production in fixed regression model was 0.17. In random regression model, heritability of milk production was higher in second than first mid of lactaion period. The highest and the lowest heritability were estimated at first (0.088) and tenth (0.292) months, respectively. Estimated breeding values for sires and daughters were evaluated in both models. The mean of estimated breeding values in random regression model was significantly higher than fixed regression model. Rank correlations between breeding values of two models were 0.958 and 0.964 for sires and daughters, respectively. In conclusion, random regression model can be recommended for genetic parameter estimation, because of its higher accuracy compared to fixed regression model.

In this study the number of 71 head of conceived ewe from the flock of Lori-Bakhtiari sheep (with number of 360 head), in Sholi Station selected as randomly to determine influence of acquired colostrum immunity on mortality rate and performance of growth traits in lambs. The sampling of blood of ewe, colostrum of ewe and blood of lamb were taken 2 weeks before parturition, 1 to 8 hours after parturition and 36 hours after birth of lamb, respectively. The serum samples extracted and then measured immunoglobulin G (mg/ml) and total serum protein (gr/l) in samples. Results showed that the overall mean of immunoglobulin G (mg/ml) were 21.33, 48.48 and 7.86 for blood serum of ewe, serum colostrum of ewe and serum blood of lamb and total serum protein (gr/l) were 71.98, 114.48 and 65.77, respectively. The least square means of all traits were significantly (P<0.05) lower in died lambs. The concentration of immunity traits in serum of ewes, lambs and colostrums of ewes were not significant on performance of growth traits in lambs (P>0.05). Thus, lamb mortality can be reduced through improving the immunity level in blood of lambs by improving immunity level of ewes (through nutritional supplementation) before parturition.

This study was conducted to compare the traditional, reconstructed and semi-industrial sheep housing for different characteristics constant: building (construction Index), reproductive traits and dead rate on sheep performance in village management system, We randomly selected 13 flocks with 3578 sheep for recorded more than 100 ewes: 3 flocks on traditional, 6 flocks reconstructed and 4 flocks semi-industrial sheep house, respectively. The data were used about construction and equipment of sheep house.SAS varsion 9.1were used to carry out the statistical analyses. The results showed that mean of closed house in traditional sheep housing, reconstructed and semi-industrial sheep housing were0.94, 3.51 and 3.71 m2/head, respectively; and between traditional and two other groups were significant difference (P<0.05). The mean of yard area in traditional sheep housing, reconstructed sheep housingand semi-industrial sheep housing were0.73,3.36 and 5.13 m2/head,respectively. The yard area of traditional sheep housing significantly was less than semi-industrial (P<0.05). The mean length of feeder and feeding trough were same in different sheep housing, but feeds storage semi-industrial housing were higher than other housing system (P<0.05). Reproductive of semi-industrial sheep housing were higher than traditional sheep housing (P<0.05). The mean of daed rate in semi-industrial sheep housing significantly was lower than traditional (P<0.05). Finally, we have recommended that traditional sheep housing be reconstructed and semi-industrial housing be fully rebuilt.

The aim of this study was to compare the digestibility of sugarcane pith treated with steampressured by rumen microorganisms and rumen bacterial of Holstein cow and buffalo of Khuzestan under similarfeedingconditions. Digestibility of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) of steam treated sugarcane pith was measured by total rumen microorganisms and rumen bacterial of cow and buffalo.Two-stagedigestionmethod and gas production techniques were used. In vitro digestibility of DM of steam treated sugarcane pith by total rumen microorganisms of buffalo (63.71%) were more than cow (60.04%), also DM and ADF digestibility by the rumen bacterial of buffalo (38.18 and 22.19%) was more than cow data significantly (34.74 and 13.72%) (P<0.05). However, about the NDF and ADF digestibility by total rumen microorganisms and NDF by the rumen bacterial, digestibility of rumen buffalo was more than cow numerically (P>0.05). Regardless of thetype of microorganism, DM and ADF digestibility by rumen microorganisms of buffalo (50.94, 33.23%) was higher than cow (47.39, 28.35%) (P<0.05). Potential of gas production (B) of steam treated sugarcane pith by total rumen microorganisms and buffalo rumen bacterial (91.02, 61.25 ml) was more than cow (68.83, 24.27 ml) (P<0.05). But rate of gas production (C) of steam treated sugarcane pith by total rumen microorganisms and rumen bacterial of cow were significantly higher than buffalo (P<0.05). Partitioning Factor (PF), microbialbiomassand microbialbiomassefficiency of steam treated sugarcane pith for rumen bacterial and total rumen microorganisms of cow were significantly higher than buffalo (P<0.05). The total bacteria population of Khuzestan buffalo (1.9×105 cells/ml) was significantly more than Holstein cows (0.92×105 cells/ml) (P<0.05).

Present study was carried out to determine the chemical composition and degradability parameters of Dry Matter (DM), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF) and Organic Matter (OM) in Agropyrontauri, which isa dominant rangeland plant in Neor region (Ardabil province). Plant samples were collected at 3 stages including: vegetative growth stage, flowering stage, seeding stage and in two different elevations. 30 plants from each stage were collected and evaluated.Ruminal degradability of samples was determined by in situ technique using two ruminalcannulatedMoghani rams. There were significant differences between average amount of DM, NDF, ADF, Ash contents; and their degradability of DM, ADF, NDF and OM including rapid degradable portion (a), slow degradable portion (b), constant rate of degradability (c) and Effective Degradability (ED) in different phenological stages (P<0.05). Results showed thatby developing phenological stages the average amount of DM, EE, Ash contents and parameters of DM and NDF degradability were decreased, however the mean amount of ADF, NDF and OM were increased (P<0.01). The highestaverage amount values for a and b portions of DM were observed in vegetative growth stage, however the lowestaverage amount values were in seeding stage. Moreover, effect of height on NDF and degradability parameters of DM and NDF was significant (P<0.05). Generally, present study showed that maturity of plant led to decrease in amount of rumen degradability and nutritional value of plants.

This experiment has conducted to assess the utilization of urea treated date palm leaves in fattening of buffalo male calves. In order to increase the nutritive value of date palm leaves, it treated by 5 percent of urea. The experiment was done based on Randomized Complete Blocks Design with three treatments and five replications during 138 days. The initial 15 days of experiment was considered as adaptation period. Treatments include three diets containing zero (control), 12.5 and 25 percent (on dry matter basis) of urea treated date palm leaves that replaced part of the forage (bagasse) ration of animals. The diets were included 50 percent forage, 50 percent concentrate. Treated date palm leaves contained 14.67±0.18 percent crude protein and 0.74±0.06 Mcal/Kg metabolizable energy. Experimental measurements included daily feed intake, daily weight gain and feed conversion ratio were 6.81, 7.25, 7.11 kg and 0.845, 0.889, 0.902 kg and 8.24, 8.19, 7.97 respectively. The results showed there were no significant differences between treatments for all factors (P>%5). It was concluded that 25 percent of ration can be used date palm leaves treated by 5 percent of urea in fattening buffalo's calves ration (on dry matter basis).