Iranian Journal of Animal Science
Year:2017 | Volume:48 | Issue:2|Papers Count:17

Understanding of population genetic structure is valuable for better implementation of breeding programs and most importantly, preservation of genetic resources. Genomic data provide an opportunity to consider complex evolutionary history of populations and reconstruct rare historical events. In this research, the structure of Iranian buffalo populations was studied by using principal component analysis and discriminant analysis principal component methods. For this purpose, the number of 404 buffalos from three breeds including North, Azari and Khozestani were sampled and genotyped by SNPChip 90k from Padano Company in Italy. The results of principal component analysis and discriminant analysis principal component showed a clear picture of the genetic structure of the studied populations. Assessing the optimal number of clusters with criteria BIC, K=3 by the DAPC method showed the best results. The result of cross-validation for retaining principal components was optimized to 50 first components that showed the lowest MSE. In this study, DAPC predicted assignment of individuals to clusters and membership probabilities with 100% accuracy. PCA method was not able to provide a group assessment and DAPC method outperformed than PCA in achieving a clear variance difference between populations. DAPC method can be applied in quality control and stratification population correction of GWAS as an alternative to the PCA because of summarizing the genetic differentiation between groups and overlooking within-group variation and providing better population structure.

The aim of this study was to estimate the accuracy of genomic breeding values using GBLUP (Genomic Best Linear Unbiased Prediction) model and compare it with the traditional method with (BLUP) and without (BLUP_noPed) pedigree by computer simulation. In this study, a genome with 30 pairs of chromosomes, 3000 QTL and 45000 marker (SNP) was simulated. The different scenarios including two effective population of 100 and 1000 animals, two reference population size of 1000 and 2000 animals and three heritabilities, low (0.05), medium (0.30) and high (0.5) were investigated. The criteria were accuracy, bias and mean square error (MSE) of breeding value to compare traditional and genomic methods. The results showed that the accuracy of breeding values increased with increasing heritability. GBLUP mehtod was more accurate than BLUP_noPed in all scenarios and the former model had more performance in higher heritability compared with BLUP model. The accuracy of genomic breeding values decreased about 11% with increasing effective population size 100 to 1000; however, the accuracy of traditional methods was not affected by changing effective population size. Increasing the reference population size 1000 to 2000, the accuracy of genomic breeding values was improved by 5%. Although, the bias (underestimate) was higher for genomic than traditional methods in all scenario; but the MSE of breeding values was lower for GBLUP than BLUP model with increasing reference population size and heritability. Therefore, GBLUP method can be used to select top animals in populations without pedigree.

The current study was carried out to evaluate the effect of Letrozole feeding on plasma LH and FSH concentrations and testicular histology in Ross 308 broiler breeder roosters. Twenty 40-week old roosters were randomly divided into four groups, individually housed and fed different levels of capsulated Letrozole including 0 (L0), 0.5 (L0.5), 1 (L1) or 1.5 (L1.5) mg/bird/day for 12 consecutive weeks. Blood sampling was done on 1th, 3 th, 5 th, 7 th and 9th weeks of trail. Testicular histology was assessed on samples from last week (12th) of experiment. According to the results, plasma LH and FSH levels, seminiferous tubule diameter and epithelium thickness as well as Leydig cell numbers were significantly increased in Letrozole treated groups compered to control group. The highest concentration of FSH and LH were recorded for L1 (10.39 ±0.11 and 2.93±0.08) and L1.5 (9.5±0.2 and 3.17±0.08) groups, respectively. Both L0.5 and L1 groups had significantly higher spermatogonial numbers than control group. However, blood vessel numbers were not significantly affected. In conclusion, orally feeding Letrozole (1 and 1.5 mg) could improve gonadotropin concentration and testicular histology parameters of male broiler breeders at 40 weeks of age. Further studied are needed to confirm these results and extend them to final fertility.

In the this research, 38 Holstein dairy cows (18 heads low production and 20 heads high-production) were selected randomly and blood samples were taken their from tail vein. DNA was extracted from whole blood with phenol-chloroform. PCR amplification of 750bp from 37 to 39 exons of FASN gene was performed using one pairs of special primers. Sequencing of the amplified region was performed by the Sanger method. Sequence data of other species was achieved and aligned by searching its genome database (NCBI). The nucleotide substitution rate of the sequences and molecular evolution of the FASN were calculated by maximum likelihood and neighbor-joining method, respectively and phylogenetic tree was constructed. Evolutionary and phylogenetic tree analysis was performed using MEGA6 and Dnasp5.1 software' s. Bioinformatics analysis results showed that the substitution percentage of purines was more than pyrimidine nucleotides. The numerical value of dN/dS in two groups of dairy cow and in comparison with that of other species were 1.16 and 1.12, respectively which indicating positive selection during evolution of this gene. Phylogenetic tree for the FASN gene in mammals shows close relationship between Buffalo and Bison, as well as Cats and Cheetahs (%98 and %57, respectively).The results show that over the years segregation and selection of new varieties, resulted in the development of new varieties, new proteins and also stabilizes their performance during the evolution and advance progress toward their performance has been purified.

In this study, Bayesian approach via Gibbs sampling was used to predict unknown parameters of five equivalent Genomic Best Linear Unbiased Predictions (G-BLUP), each with different scale of G matrix by using allele frequency of founder population (Gfoun), allele frequency of reference population (Gref), allele frequency equal to 0.5 (G05), a normalized matrix with average diagonal coefficients equal to 1 (Gnorm) and a weighted G matrix with A matrix (Gwei). A random mating population and a selected population were used to compare results of a trait with heritability of 0.25 on a genome constructed of three chromosomes with 105 QTLs and 3000 single nucleotide polymorphisms. The results showed that higher variance existed in the elements of G matrices compared with A matrix. Average diagonal and off-diagonal elements except Gnorm and Gwei were higher than corresponding elements in A. Gnorm-BLUP and G05-BLUP methods led to inflated genetic variance in contrast other three methods and this inflation was lower in selected population. Average accuracy over 5 G-BLUP in random population was 0.084 higher than selected population (0.762 vs.0.652) and bias was 0.041 lower (0.026 vs.0.04). Bias of prediction of true breeding value of selected population by using Gwei almost was zero but with Gref greater than 0.06. The greatest accuracy and the smallest bias can be obtained by using allele frequency of reference population that re-scaled with A matrix.

The aim of this research was to evaluate the effect of in ovo injection of different ratios of L- arginine to L- lysine on body growth, muscle production and blood metabolites concentration of day old Ross broilers chicks. A total of 210 fertile Ross 308 broiler breeder eggs were used in a completely randomized design with seven experimental groups of 30 individual eggs in each treatment. The experimental treatments included: sham-control (sterile distilled water injected), control (non-injected), and injection of solutions with 75.7, 80.7, 85.7, 90.7 and 95.7 percent L-arginine to L-lysine ratios. On hatching, the chicks were weighed and their blood samples were collected. Then, chicks were euthanized and their carcass traits were weighed. According to the results of this study, the maximum hatchability percentage was observed in 90.7 percent of L- arginine to L- lysine ratio. The results also showed that the in ovo injection of different L- arginine to L- lysine ratio up to 90.7 percent resulted in significant increase in chick weight (P<0.01), relative weight of scalped carcass (P<0.01), carcass efficiency (P<0.01), thigh relative weight (P<0.05), breast muscle relative weight (P<0.01) and relative weight of liver (P<0.05), whereas blood plasma urea concentration was significantly (P<0.05) decreased. In overall, results indicated that in ovo injection of 90.7% L-arginine to L-lysine ratio is an advisable ratio for improving muscle growth, blood serum metabolite concentrations, and hatchability percentage of broilers.

The effects of replacing 0, 15 and 20 of corn by percent oak acorn (OA), in diets containing recommended and twice recommended level of methionine by NRC (1994) on performance of broilers were investigated.528 one-day-old Cobb 500 broiler chicks in a 2×3 factorial arrangement based on completely randomized design with four replicates of 22 chicks were used. Chicks fed with diets containing 15 and 20 percent OA had lower body weight gain and higher feed conversion ratio compared to those fed with diet without OA, in all experimental periods (P<0.05). The increasing dietary methionine level as Twice as NRC (1994) recommendation reduced feed intake and body weight gain in finisher and overall experimental periods significantly (P<0.05). No significant interaction was observed between dietary OA utilization and methionine for performance parameters. The 20 percent dietary OA utilization had undesirable effect on some tibia characteristics (P<0.05). Generally, the substitution of 15 and 20 percent of dietary corn with OA resulted in reduction in broilers performance and increasing the dietary level of methionine could not prevent this situation.

A total of 392 one-day male broiler chicks (Ross 308) were used to evaluate the effect of grain source (corn or Sardari, Zarrin and Azar-2 wheat cultivars) with or without a carbohydrase mixture enzyme an chicks performance from day 1 to day 49. A completely randomized design (seven treatments, four replicates and 14 chicks per replicate) was used. Results showed that birds fed diet contained Zarrin vs. Sardari or Azar-2 had higher body weight at 11, 25 and 42 days of ages. Birds fed Zarrin vs. Azar-2 diet had higher feed intake from 1 to 11 d. Bird’s fed diet with Sardari treatment showed lower serum glucose and total protein at 20d, lower carcass and pancreas relative weight (%) at 21 and 41d, respectively. Enzyme supplementation significantly improved bird’s body weight at 11, 25 and 42 d. Enzyme improved feed conversion ratio from 12 to 25 and 43 to 49 days of age. In addition, birds fed enzyme contained diet had significantly lower gizzard and pancreas relative weight (%) at 21d. In conclusion, the findings show that birds fed diet containing Zarrin cultivar or supplemented with enzyme mixture had higher performance.

This research was conducted to evaluate feedlot performance, carcass characteristics, nutrient digestibility, blood metabolites, chewing activity, and economic return of Afshari and Lori lambs feeding a high concentrate diet. Eight Afshari lambs and 8 Lori lambs (28.4±3.8 kg initial weight, 3-4 months of age) were assigned into a completely randomized design for 104 days and fed a diet consisting of (DM basis) 80% concentrate mixture and 20% forage. Results indicated that feed intake (P=0.01), final body weight (P=0.03) and average daily gain (P=0.03) were greater in Afshari than Lori lambs. However, feed conversion ratio and nutrient digestibility were not different between two groups (P<0.05). Despite higher feed cost in Afshari lambs, income over feed cost were greater for Afshari than for Lori lambs (P<0.05). Weight percentage of fresh carcass dressing, concentrations of blood metabolites, total short chain and individual fatty acids were similar between two groups. Compared to Afshari lambs, Lori lambs showed greater total chewing activity per g of DMI as well as ruminal pH (P<0.05). Despite similar feed efficiency between two breeds, feeding high concentrate diet is recommended to Afshari lambs because of better fattening performance and economic return.

The purpose of this research was to evaluate the effect of five levels of vitamin A including 0, 4, 000, 8, 000, 16, 000 and 32, 000 international units per kilogram of diet on productive and reproductive parameters in Japanese quail.320 adult Japanese quails were used in a complete randomized block design with 5 treatments, 4 replicates and 16 quails (12 female and 4 male) in each replicate for 42 days. Percentage of egg production and egg weight were recorded weekly and their mean were calculated for total period of experiment. After two weeks of experiment, food intake weight was measured to determine the daily food intake amount and food conversion ratio and was extended for total period. At the end of experiment, 5 eggs of each replicate were randomly selected for evaluate egg quality parameters, and also, 40 eggs from each replicate were incubated for evaluation the reproductive parameters. The different levels of vitamin A in diet had no significant effect on food intake, egg production rate, weight and quality parameters of eggs (P>0.05). Fertility, hatchability, and embryonic mortality rates as well as hatched chick weight were not affected by different levels of dietary vitamin A (P>0.05). The lowest food conversion ratio was observed in 32000 IU/kg of vitamin A (P<0.05).

This research was conducted to examine the effect of addition 400, 200 and 200 mg/kg carvacrol, menthol and thymol, respectively, to a non- supplemented control diet on carcass fat deposition and distribution pattern in broilers.96 female Ross 308 broiler chicks were used in 4 treatments and 12 replicates of two birds in each from 14 to 42 days of age. Ileal fat digestibility was decreased by 8.02, 5.06 and 15.08 percent in the birds receiving carvacrol-, menthol- and thymol-supplemented diets, respectively (P<0.01). The mean of carcass fat and feather fat percentage was reduced in the birds fed diets containing carvacrol by 6.08 and 31.57 percent, respectively, in comparison to control (P<0.05). The addition of carvacrol to diet resulted in 6.86 (P>0.05), 6.95 (P>0.05), 38.01 and 10.50 (P<0.05) percent reduction in abdominal, neck, subcutaneous and thigh intramuscular fat deposits, respectively. The back fat thickness of chicks receiving diets containing carvacrol, thymol and menthol was significantly (P<0.05) lower than that of control group. The blood serum concentration and ratio of estradiol, dehydroepiandrosterone, testosterone, cortisol and progesterone of chicks fed diets containing carvacrol, thymol and menthol had no significant difference with control (P>0.05). According to the results of this study, it seems that carvacrol and thymol will result to reduction in ileal fat digestibility and carcass fat of broilers especially in subcutaneous fat.

This research was conducted to evaluate broiler response toin-ovo feeding of beta-hydroxy beta-methylbutyrate (HMB) and dextrin and the timing of the first feed deprivation using Box-Behnken design and response surface methodology. On day 18 of incubation, 1500 fertile eggs from Ross 308 strain were randomly assigned to experimental treatments of Box-Behnken design, each with 4 replicates, as 3 levels in-ovo injection of HMB (0, 0.5 and 1 %) and dextrin (0, 20 and 40 %), and 3 levels of the first water and feed restriction time (6, 27 and 48 hours). The in-ovo injection of dextrin led to significant lower hatchability (P<0.05), whereas in-ovo injection of HMB had no significant effect on hatchability (P>0.05). In European efficiency factor models, the jejunal villi surface area and glycogen contents of liver and breast muscle at 7 days of age, the linear components showed highest contribution (0.61 to 0.79) of variation in chick responses. The results of this research showed that maximum European efficiency factor at 7 days of age can be achieved by in-ovo administration of HMB and dextrin (0.54 and 39.03 percent, respectively) in amnion fluid till maximum 20.79 hours feed deprivation after hatch.

The aim of this study was to evaluate the effects of different concentration of Butylated hydroxy toluene (BHT) and Butylated hydroxyanisole (BHA) on freezing capacity of Rams semen. Semen of four healthy mature ram (2.5 - 4 years) was collected, twice a week for three weeks. Collected semen samples were pooled after primary evaluation and divided into 8 groups. Then samples were diluted with one of the treatments [including negative control (without antioxidants and DMSO), positive control (without antioxidants, with DMSO), BHA-0.5 (containing 0.5 mM BHA), BHA-1 (containing 1 mM BHA), BHA-2 (containing 2 mM BHA), BHT-0.5 (containing 0.5 mM BHT), BHT-1 (containing 1 mM BHT) and BHT-2 (containing 2 mM BHT)] and were equilibrated at 4 ºC for 150 min. Afterward the cooled semen were loaded into 0.25 mL straws and were frozen in liquid nitrogen vapor. Motion characteristic (using CASA: Computer Assisted Sperm Analysis), viability and membrane integrity were assessed after thawing. The results of this study showed that addition of 2mM BHA to the extender could significantly increase total motility compared to the negative and positive control treatments (P>0.01). Also addition of 2 mM BHA significantly improved the progressive motility and membrane integrity compared to rest of the groups (P>0.05). However, different levels of BHA and BHT have not shown any significant difference in viability of ram sperm (P>0.05). So it is concluded that the addition of 2 mM BHA to the extender could improves the freezability of Ram semen.

In this study, the records of survival of 3056 kids related to the breeding station of Raini Cashmere goat were used during years 1993-2004. These records were collected in Raein Breeding station located in the Baft city, Kerman province, Iran. The data were analyzed using linear and hazard ratio models with Weibul function. These models included fixed factors such as year and month of birth, sex, type, age of dam and birth weight as quadratic covariate, and direct additive genetic, maternal additive genetic, maternal permanent environmental and residual random effects. Genetic parameters were estimated using restricted maximum likelihood procedure and different animal models contained with and without maternal and common environmental effects and sire model. The direct heritability of length of life and survival rate estimated from different linear models was low (0.01 to 0.06). The estimates of heritability in logarithmic scale, original scale and effective heritability obtained from sire and animal models with Weibull function were medium to high (0.17 to 0.70) and higher than analogous values estimated by different linear models. Medium estimates show that genetic and non-genetic factors affect survival. Hence, to improve these traits, selecting beside suitable management are necessary.

This study was conducted to evaluate the relationship between calving body condition score (BCS) as well as first and second milk test postpartum with clinical and subclinical mastitis prevalence. After calving 117 multiparous cows were divided to two groups based on their BCS as fat and normal conditioned and milk samples were taken in week one and two postpartum. The results showed BCS at calving time had no significant relationships with udder health. Milk protein and fat had significant associations with udder health in week 1 and 2 postpartum; however in none of weeks no meaningful relationships were found between milk fat to protein ratio with udder inflammation. Therefore, calving BCS and fat to protein ratio are not reliable markers for clinical or subclinical mastitis incidence; however milk fat and protein in week 1 and 2 postpartum can be used as proper markers for predicting subclinical mastitis in dairy cows at early lactation.