JWSS - Journal of Water and Soil Science

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In this study 2510 records of reproductive traits from the mating of 879 ewes with 164 rams of Bakhtiari sheep breed, during 1989 to 1997, were used in order to estimate the effects of environmental factors on their reproductive performance.

The mean and standard errors of reproductive traits were as follows: conception rate, 0.9±0.01 number of lambs born per ewe exposed, 1.06±0.01 number of lambs born alive per ewe exposed, 1.01 ±0.0l, number of lambs weaned per ewe exposed, 0.93±0.01 litter size alive at birth, 1.10±0.01 litter size at weaning, 1.01±0.02 and number of lambs weaned per lambing ewe, 1.09±0.01. The effect of joining year was highly significant (P, 0.01) for all of the considered reproductive traits. Age of ewe at joining time was also a significant (P<0.05 and 0.01) source of variation for most of the reproductive traits. Maximum reproductive performance occurred for ewes of 4 to 5 years of age. Mating time was also a significant factor (P<0.05 and 0.01) for all of the reproductive traits. Maximum reproductive performance occurred for ewes mated during the first half of the mating season. Type of birth was a highly significant factor (P<0.0l) for the number of lambs alive and weaning traits. However, due to significant effects of environmental factors on considered traits, and in order to increase reproductive efficiency, one should improve environmental conditions (barn, management, feeding system and ... ) as well as organizing mating plan for the first half of the mating season and make a suitable age combination of ewe herd. In this combination, decreasing the percentage of ewes older than five years could benefit herd performance.

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Three levels of urea (0, 0.5 and 0.75% on fresh weight basis) were added to whole corn plants to investigate their effects on the chemical composition, and digestibility in 16 Ghezel male lambs using a completely randomized design. Rumen degradability and nutritive values were also evaluated.

 pH, total nitrogen and ammonia-N concentration of silages increased (P<0.05) with the addition of urea. Total nitrogen apparent digestibility was higher (P<0.05) with the urea addition. Nitrogen balance in ruminal fluid increased (P<0.05) with the addition of 0.5% urea. pH and ammonia-N concentration increased (P<0.05) with the addition of urea until 1.5 hr post feeding. Blood serum urea nitrogen concentration was higher (P<0.05) with the addition of urea until 6 hr post feeding. Potential degradability of dry matter and organic matter was higher at 0.5% urea level. Average daily gain increased with the urea addition and was highest (212.88 gr) at 0.75% urea. Subcutaneous fat depth was significantly (P<0.0l) lower for the sheep fed with 0.5% urea-treated silage as compared to other treatments. The results indicated that feed efficiency may be improved by urea addition and that the addition of urea (0.5% on fresh weight basis) may be recommended in order to increase the feeding value of whole corn plants.

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In this study, 14322 growth trait records of 2387 sheep bred and reared in the Rearing and Breeding Station of Bakhtiari Sheep during 1989-1997 were used to estimate the phenotypic, genetic, and environmental trends for some of the growth traits using Animal Model for lambs, rams, and ewes. The genetic trend of birth weight, weaning weight, six month's weight, daily gain from birth to weaning, daily gain from weaning to six month and daily gain from birth to six month were 12.2 (+2.9), 19.6 (+5.5), 28.7 (+8.7), .15(+0.04), 0.06 (+0.05) and 0.014 (+0.04) gr. for ewes as an indicator of genetic level of the herd respectively. Also, average of the genetic change rate per year for rams and lambs were calculated. Overall, the maximum progress rate was for six-month body weight (28.7 gr. per year) and the next was weaning weight (19.6 gr. per year). The results for lambs and rams also showed that these traits had the same rank for the genetic progress. The progress could be due to direct selection for these traits in the selection index criterion although there were negative phenotypic and environmental trends during the study years. Negative phenotypic and environmental trends could be due to bad environmental conditions, especially to nutrition of the sheep in an unsuitable (drought) climate during the study years. .

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The aim of this research was to study the effect of treatment with oyster mushroom (Pleurotus sajor-caju) on digestibility of Glycyrrhiza glabra L. pulp. Pleurotus sajor-caju was inoculated on sterilized wheat grains. Two weeks after growth at 25 °C it was added to the sterilized Glycyrrhiza glabra L. pulp in nylon bags. After two weeks (at 25 °C), mycelia grew on the pulp and were used for treatment. Digestibility coefficients were measured in 12 Ghezel rams. Dry matter, crude protein (CP) and nitrogen free extract (NFE) increased, but ash content, cell wall (NDF) and lignin (ADL) decreased significantly in fungal-treated as compared with non-treated pulps. Crude fiber (CF) and ADF contents were not significantly affected by the treatment. There was a tendency for crude fat (EE ether extract) to decrease by fungal treatment (p=0.08). Mean dry matter intake and digestibility coefficient of dry matter were higher in sheep which were fed the fungal-treated pulp compared with the control group. Digestibility coefficients of CP, CF, organic matter (OM), EE, NFE, NDF, ADF and ADL were significantly greater in fungal-treated pulp than in control group. Treatment with P. sajor-caju increased the nutritive value and digestibility of Glycyrrhiza glabra L. pulp (P<0.05), but culture of this fungus was not possible on non-sterilized pulp, which hinders its field application.

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Data from the birth weight (BW), the average daily gain from birth to weaning (ADG) and the weaning weight (WW) of 1182, 1099 and 1099 lambs were respectively collected and applied to estimate the maternal effects on heritabilities as well as on the determination of the environmental factors. The data were collected from Shahrbabak Sheep Breeding Research Station within five year, from 1993 to 1998. The effects of the year of birth, the age of the dam and its sex on all the traits were significant. The type of birth had no effect on BW but it was significant for the other two traits. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two-trait animal models. Based on the most appropriate fitted model, direct heritability of BW, ADG and WW were estimated at 0.10± 0.06, 0.21 ±0.08 and 0.22± 0.09, respectively. The maternal heritability for the three traits was also estimated at 0.27± 0.04, 0.15 ±0.05 and 0.19 ±0.05, respectively. Direct genetic and phenotypic correlations between BW and ADG BW and WW ADG and WW were estimated at 0.85 and 0.41 0.82 and 0.48 and 0.99 and 0.99, respectively. Ignoring maternal effects in animal model caused overestimation of direct heritability. Thus maternal effects are significant sources of variation for early growth traits and their ignorance in the animal model causes inaccurate genetic evaluation of the lambs.

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In modern programmes of animal breeding, the polymorphisms of the milk proteins can be used as marker systems. Beta-Lactoglobulin is the major milk whey protein in the ruminants. The BLG coding gene located on ovine chromosome 3. This protein, synthesis in the mammary glands during pregnancy and the lactation stages. Studies have indicated that this protein is polymorphic in the many breeds of sheep. This is the result of a single base pair substitution in the Beta-Lactoglobulin gene that also rises to the RsaI restriction fragment length polymorphism (RFLP). The aim of this work was to analyze the genotype distribution of Beta-Lactoglobulin in sheep. Blood samples were supplied from 142 sheep of the 5 breeds (Ghezel, Afshari, Moghani, Makoii and Arkharmerino). Genomic DNA was extracted from the 200ul blood sample according to Boom et al. (1989) method modified by Shaikhayev (1995). The Gel monitoring and the spectrophotometeric methods were used for determination of the DNA quality and quantity. the Primers BLG5 and BLG3 amplified a 452 bp fragment from the exon II of the ovine Beta-Lactoglobulin gene. the Products of the amplification were recognized by the electrophoresis on the 1% agarose gel stained with ethidium bromide. The RsaI enzyme was used for restriction of the PCR products. The digested products were separated by the electrophoresis on the 8% nondenaturant polyacrylamide gel and visualized after staining with the ethidium bromide on UV transillumination. The popGen32 software (ver.1.31) was used to estimate the allele and the genotype frequencies, the Hardy-Weinberg equilibrium and dendrogram of the genetic distance. The frequency of A-allele in Ghezel, Afshari, Moghani, Makoii and Arkharmerino breeds was 56%, 34%, 36%, 53% and 48% respectively. The populations were in Hardy-Weinberg equilibrium except to Afshari breed. The lowest genetic distance was observed between Moghani and Afshari breeds and the highest genetic distance between Ghezel and Afshari breeds. The results of this study indicated that PCR-RFLP is an appropriate tool for evaluating genetic variability in sheep.

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In this study external fat-tail dimensions (upper, middle and lower width, length, length of gap, depth and upper circumference) and fat-tail weights collected on 724 Lori-Bakhtiari sheep were used to study external fat-tail dimensions and their relationships with fat-tail weights. Sheep were 3 months to 6 years old and slaughtered at the industrial slaughter house of Joneghan in Chaharmohal and Bakhtiari province in 2003. The mean of fat-tail dimensions were estimated as 15.83, 23.85, 24.73, 26.52, 14.96, 14.12 and 52.59 cm for upper width, middle width, lower width, length, length of gap, depth and upper circumference, respectively. Fat-tail weight varied from 0.10 to 20.60 with overall mean of 2.71 kg. Fat-tail percentage varied from 1.18 to 37.18 with overall mean of 11.87 percent. The effects of fixed factors of age, sex and body condition of sheep on all of traits were highly significant (p<0.0001). The least square means of all traits except fat-tail percentage were increased with increasing age of sheep. Lowest least square mean (± s.e) of 2.12 ± 0.25 kg fat-tail weight and 7.91 ± 0.72% fat-tail were observed for sheep having body condition score of 1 and the highest least square mean with fat-tail weight of 9.84 ± 0.56 kg and fat-tail percentage of 20.59 ± 1.63 were observed for sheep having body condition score of 5. Estimation of correlation coefficients among external fat-tail dimensions and fat-tail weight were positive and varied from 0.60 between upper fat-tail width and fat-tail weight to 0.83 between upper circomference of fat-tail and fat-tail weight. Upper circumference of fat-tail accounted for %69.5 of variation of fat-tail weight. This study showed that fat-tail weight in live sheep of Lori-Bakhtiari could be estimated using external fat-tail dimensions with very high accuracy (r = 0.904).

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Genetic variation within and between five Iranian sheep populations including Sanjabi (SAN), Kordi Kordistan (KKO), Kordi Khorasan (KKH), Mehraban (MEH) and Moghani (MOG) was assessed using six microsatellite markers (McMA2, McMA26, MAF64, OarAE64, OarCP26 and OarFCB304). The PCR reactions were successfully perfomed with all primers except OarAE64. All locus-population combinations were at Hardy-Weinberg equilibrium except McMA2 in MOG population (P<0.005). Polymorphism criteria showed that the five studied loci were polymorphic in all populations. The lowest D_A genetic distance (0.234) was observed between KKH and KKO and the highest (0.388) between SAN and MOG populations. The dendrograms based on D_A distances were drawn using unweighted pair-group method using an arithmetic average (UPGMA) and neighbor-joining (NJ) method. KKO, KKH and SAN were grouped together at one cluster and MEH and MOG at another by both methods. The average expected heterozygosity for each populations (as interpopulation variation) ranged from 0.744 to 0.847 for KKH and MEH, respectively. The estimated time of divergence for two Kordi populations (KKO and KKH) was 445 years that complies with historical evidences. The findings of this research confirmed that microsatellite variation could be a useful tool for screening of investigating biodiversity among domestic animals.

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In order to identify polymorphic microsatellite markers and evaluae genetic variation within Baluchi sheep population, nineteen microsatellite loci were studied. Whole Blood samples were collected from 156 sheep at north eastern animal breeding station of Iran (Abbasabad-Mashhad). DNA was extracted by salting-out procedure with some modifications. Polymerase chain reactions were successfully done except for UNC5C locus. PCR products were electrophoresed on 8% denaturing polyacrylamide gels stained according to rapid silver staining procedure. The genotype and allelic frequencies were calculated by direct counting and used for estimating of different polymorphism and genetic variation criteria. This population wasn't at Hardy-Weinberg equilibrium except for OarAE101 locus (P<0.005). Heterozygosity (gene variation) ranged from 0.1 to 0.93. BULGE5E and BM1329 loci were monomorphic. In conclusion, this investigation showed high polymorphism at the studied loci, so they could be used in future studies.

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In this study 5025 records from the Lori-Bakhtiari sheep stud were used to predict phenotypic, genetic and environmental change in ewe traits from 1989 to 2004. Best linear unbiased prediction (BLUP) of breeding values were estimated by Drivative Free Restricted Maximum Likelihood (DFREML) procedure using single and multi-trait animal model. Phenotypic, genetic and environmental trends were calculated by regressing of the average phenotypic values, predicted breeding values and environmental values in the year of ewe birth respectively. The estimated phenotypic trends were –0.1223 kg for ewe body weight, -0.0415 kg for greasy fleece weight, 0.6639% for conception rate, 0.0003 for number of lambs born per ewe lambing, 0.0094 for number of lambs weaned per ewe lambing, 0.0380 kg for total birth weight per ewe exposed and 0.4227 kg for total weaning weight per ewe exposed. The estimated genetic trends were 0.0603 kg, -0.0004 kg, 0.0183%, -0.0012, -0.0007, 0.0030 kg and 0.0211 kg from single trait analysis and 0.0549 kg, -0.0006 kg, 0.0089%, -0.0008, -0.0008, 0.0030 kg and 0.0230 kg respectively from multi-trait analysis. The estimated phenotypic and environmental trends were significant but genetic trends were not significant (P<0.05) for often traits.

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Variance components and genetic parameters of body weight of Mehraban sheep were estimated by univariate and random regression models. This was done by using body weight records of 2746 Mehraban lambs related to flocks under supervision of the Agriculture Organization of the Hamadan province, collected between 1990 and 2005. In both methods, variance components estimates were obtained by restricted maximum likelihood (REML) using DFUNI and DXMRR programs, respectively, via DFREML 3.1 software package. Results showed that variance components obtained from RR models (except for residual variance) in some ages were higher than those obtained from univariate models. Direct heritability (h2) estimates from univariate and RR models were approximately equal to weaning age but, overall, RR estimates were higher than those obtained from univariate analyses. Maternal heritability estimates (m2) from RR models were higher than univariate models’ estimates, and showed a different pattern of variation with age. Correlations between predicted breeding values from univariate and RR models for birth weight and weaning weight were 0.72 and 0.70, respectively. Results showed that estimates of variance components and genetic parameters by RR models were affected by data structure and in case of the need for genetic parameters, especially those related to body weight late in lambs’ life, estimates of univariate analyses should be preferred.