Comparison of different models for genetic evaluation of egg weight in Mazandaran fowl

1. The aim of the present study was to compare different models to estimate variance components for egg weight (EW) in laying hens.

2. The data set included 67 542 EW records of 18 245 Mazandaran hens at 24, 28, 30, 32 and 84 weeks of age, during 19 consecutive generations. Variance components were estimated using multi-trait, repeatability, fixed regression and random regression models (MTM, RM, FRM and RRM, respectively) by Average Information-Restricted Maximum Likelihood algorithm (AI-REML). The models were compared based on Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC).

3. The MTM was the best model followed by the Legendre RRMs. A RRM with 2nd degree of fit for fixed regression and 3^rd and 2^nd degrees of fit for random regressions of direct additive genetic and permanent environmental effects, respectively, was the best RRM. The FRM and RM were not proper models to fit the data. However, nesting curves within contemporary groups improved the fit of FRM.

4. Heritability estimates for EW by MTM (0.06–0.41) were close to the estimates obtained by the best RRM (0.09–0.45). In both MTM and RRM, positive genetic correlations were estimated for EW records at different ages, with higher correlations for adjacent records.

5. The results suggest that MTM is the best model for EW data, at least when the records are taken at relatively few age points. Though selection based on EW at higher ages might be more precise, 30 or 32 weeks of age could be considered as the most appropriate time points for selection on EW to maximise genetic improvement per time unit.     

The study of developmental capacity of vitrified mouse blastocysts in different straws after transfer to mouse pseudo pregnant

Vitrification is the commonly used method for long-term storage of pre-implantation mammalian embryos. It is an essential part of assisted reproductive technologies. The re-expansion rate, pregnancy and birth rate of vitrified blastocysts using CPS were compared with OPS and Conventional Straw. Female NMRI mice were injected with Gonadotrophins in order induce them for super ovulation. At that time the mice were sacrified by cervical dislocation and dissected of mouse abdomen. The uterine horns were existed blastocysts were collected in PBS and randomly allocated to four groups: vitrification in CPS, conventional straw, OPS and untreated controls. The vitrification solution was EFS40%. After storage for 1 month in liquid nitrogen, the blastocysts were thawed in 0.5 M sucrose for in vitro culture in M16 medium. After 6 h of culture, the numbers of expanded blastocysts was recorded and ready for transfer to uterus of pseudo pregnant mouse. The re-expansion rate of the CPS group (72.1%) was significantly higher (p < 0.05) than OPS (52.55) and C.S. (38.6%) groups. The pregnancy (70%) and birth rate (45%) of blastocysts in CPS were similar to those of fresh blastocysts (80% and 45.5%) and the pregnancy (10%) and birth rate (5.1%) in Conventional Straws lower than OPS (20 and 7.5%), but were not significantly different. Mouse blastocysts vitrified using CPS had a better result compared with OPS and Conventional Straw. The value of CPS for vitrification of blastocysts may also merit investigation.     

The Role of Biodegradable Engineered Nanofiber Scaffolds Seeded with Hair Follicle Stem Cells for Tissue Engineering

Background

The aim of this study was to fabricate the poly caprolactone (PCL) aligned nanofiber scaffold and to evaluate the survival, adhesion, proliferation, and differentiation of rat hair follicle stem cells (HFSC) in the graft material using electrospun PCL nanofiber scaffold for tissue engineering applications.

Methods

The bulge region of rat whisker was isolated and cultured in DMEM: nutrient mixture F-12 supplemented with epidermal growth factor. The morphological and biological features of cultured bulge cells were observed by light microscopy using immunocytochemistry methods. Electrospinning was used for production of PCL nanofiber scaffolds. Scanning electron microscopy (SEM), 3-(4, 5-di-methylthiazol- 2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, and histology analysis were used to investigate the cell morphology, viability, attachment and infiltration of the HFSC on the PCL nanofiber scaffolds.

Results

The results of the MTT assay showed cell viability and cell proliferation of the HFSC on PCL nanofiber scaffolds. SEM microscopy images indicated that HFSC are attached, proliferated and spread on PCL nanofiber scaffolds. Also, immunocytochemical analysis showed cell infiltration and cell differentiation on the scaffolds.

Conclusion

The results of this study reveal that PCL nanofiber scaffolds are suitable for cell culture, proliferation, differentiation and attachment. Furthermore, HFSC are attached and proliferated on PCL nanofiber scaffolds.Key Words: Nanofiber, Electrospinning, Stem cells, Tissue engineering     

Effect of allele frequencies,effect sizes and number of markers on prediction of quantitative traits in chickens

The objective was to assess goodness of fit and predictive ability of subsets of single nucleotide polymorphism (SNP) markers constructed based on minor allele frequency (MAF), effect sizes and varying marker density. Target traits were body weight (BW), ultrasound measurement of breast muscle (BM) and hen house egg production (HHP) in broiler chickens. We used a 600 K Affymetrix platform with 1352 birds genotyped. The prediction method was genomic best linear unbiased prediction (GBLUP) with 354 564 single nucleotide polymorphisms (SNPs) used to derive a genomic relationship matrix ( G ). Predictive ability was assessed as the correlation between predicted genomic values and corrected phenotypes from a threefold cross‐validation. Predictive ability was 0.27 ± 0.002 for BW, 0.33 ± 0.001 for BM and 0.20 ± 0.002 for HHP. For the three traits studied, predictive ability decreased when SNPs with a higher MAF were used to construct G . Selection of the 20% SNPs with the largest absolute effect sizes induced a predictive ability equal to that from fitting all markers together. When density of markers increased from 5 K to 20 K, predictive ability enhanced slightly. These results provide evidence that designing a low‐density chip using low‐frequency markers with large effect sizes may be useful for commercial usage.     

Quantitative and financial evaluation of non-timber forest products (case study: Zemkan basin forests,West of Iran)

Although Zagros forests in western Iran lack industrial timber value due to the severe climate and socioeconomics problems, non-timber products are of great value and importance due to their high economic potential and also their potential to improve the welfare of forest-dwelling and forest-fringe villagers. This study was done in the forests of the Zemkan basin, an important part of central Zagros forests, Iran, to recognize the non-timber forest products (NTFP_S), investigate their potential economic value and role in people’s livelihood. Data, collected using forest cruising, participatory observations, interviews with indigenous and local persons and experts, identified wild pistachio resin, wild pistachio fruit, oak fruit and oak syrup (Shokeh manna) among the non-timber products in this basin with total potential harvestable NTFPs of 77.16, 771.602, 13248.68, and 1324.868 tons per year, respectively. The economic rent from NTFPs is 33 US$/ha/year and its total expected values with consideration of real interest rate when the exploiter invests the capital in the bank (6.4 %) and when money is borrowed from the bank to execute the incorporated projects (8.4 %) are $516/ha and $393/ha, respectively. Furthermore, families’ economic share from potential profit of NTFPs is annually $601 per household. In addition wild pistachio resin has the highest share of the total potential profit of NTFPs and its equal to 51 % of the total of potential profit of NTFPs. Therefore, it is suggested that decisions be made to increase the infrastructure and strengthen the local selling market to enhance the cash income from NTFPs. Forest participatory management practices are suggested to organize and improve traditional use of the forests.     

Sampling Strategies and Soil Characteristics for Estimation of Plant Patches Dimensions (Case Study: Inchebroun Rangelands,Golestan Province,Iran)

Survey and monitoring rangelands projects is one the important plans in rangelands management. For this purpose, the survey and monitoring methods could be time-consuming and costly. Sampling strategies of plant patches are effective in sampling procedures that cause minimizing sampling variance and time. In this study, for decreasing sampling time and cost, increasing speed, plant patches parameters (including length, width, height, area, and distance between the patches) were compared. Three transects with 50 m length at three aspect slopes were located randomly systematic at the selected site with different grazing intensities. Soil samples for nitrate (NO₃^?), total nitrogen (TN), ammonium (NH₄⁺), phosphorus (P), sodium absorption ration (SAR), soil acidity or soil reaction (pH), sodium (Na), electrical conductivity (EC), organic carbon (OC), and potassium (K) content were taken in these transects. The data were subjected to analysis of variance (ANOVA), and the average of the measured parameters in the transects was compared by Duncan Multiple Range test using SPSS₁₆ software. The soil characteristics compared between the regions were analyzed with Discriminant Function Analysis using STATISTICA₁₀ software. Results showed that the transect slope aspect and soil characteristics had an effect on measured parameters. It was suggested to withdraw the located transect at one of the North or South and West or East Slope aspects for increasing sampling efficiency. It was also suggested that to avoid time consumtion, sampling can be recorded on plant patches’ width instead of area. It is also suggested that it would be better to record the length of the plant patches instead of their area in the non-grazed zones and record the length and the width of the plant patches in the moderate- and the high-grazed zones.     

Over-mature beech trees (Fagus orientalis Lipsky) and close-to-nature forestry in northern Iran

Oriental Beech is the most important commercial tree species in northern Iran. In recent years wood production companies interested in felling large beech trees for profit have challenged advocates of close-to-nature silviculture who favor conservation. Our study objective was to assess the economic value of over-mature beech trees by relating tree diameter (DBH) to amount of decay. Based on the location of onset of decay, we categorized three types of decay as stump, stem, and crown decay. Trees of greater diameter (age) typically showed greater decay in the stem. Percent of decayed volume, diameter of decayed tissue, and length of decay in tree stems varied between 0.5%?64.3%, 15 cm?75 cm, and 2.0?19.5 m, respectively. With increasing trunk diameter, the proportion of truck decay increased. Red heart and dark red heart constituted 25% and 14.3% of sampled trees, respectively. However, we found no correlation between intensity of stem decay and morphological characteristics of trees. Seedlings were not abundant around the bases of over-mature trees, suggesting that the trees did not contribute to regeneration of the stand. Beech trees of diameter >1 m do not provide valuable round wood for industries and cause to raise wood production costs. We recommend that these trees >1 m DBH should be retained in forest stands because of their low commercial value but high ecological and conservational values such as maintaining biodiversity in forest ecosys-tems.     

Heritabilities and genetic correlations of economic traits in Iranian native fowl and estimated genetic trend and inbreeding coefficients

1. Genetic parameters were estimated in a base population of a closed experimental strain of fowl. Data were obtained on 21 245 Iranian native hens (breeding centre for Fars province) subject to 8 successive generations of selection. This population had been selected for body weight at 12 weeks of age (BW12) and egg number during the first 12 weeks of the laying period (EN), mean egg weight (EW) at weeks 28, 30 and 32, and age at sexual maturity (ASM). 2. The method of multi-traits restricted maximum likelihood with an animal model was used to estimate genetic parameters. Resulting heritabilities for BW12, EN, EW and ASM were 0.68 +/- 0.02, 0.40 +/- 0.02, 0.64 +/- 0.02 and 0.49 +/- 0.02, respectively. 3. Genetic correlations between BW12 and EN, EW and ASM were 0.11 +/- 0.33, 0.54 +/- 0.21 and -0.12 +/- 0.03, respectively. Genetic correlations between EN and EW and ASM were -0.09 +/- 0.03 and -0.85 +/- 0.01, respectively, while between EW and ASM, it was 0.05 +/- 0.03. 4. The overall predicted genetic gains, after 7 generations of selection, estimated by the regression coefficients of the breeding value on generation number were equal to 22.7, 0.17, 0.04 and -1.38, for BW12, EN, EW and ASM, respectively. 5. A pedigree file of 21 245 female and male birds was used to calculate inbreeding coefficients and their influence on production and reproduction traits. Average inbreeding coefficients for all birds, inbred birds, female birds and male birds were 0.048, 0.673, 0.055 and 0.047%, respectively. Regression coefficients of BW12, ASM, EN and EW on inbreeding coefficient for all birds were equal to 0.51 +/- 0.001, 0.31 +/- 0.003, -0.51 +/- 0.003 and 0.03 +/- 0.001, respectively.     

Impact of conformation traits on functional longevity of Holstein cattle of Iran assessed by a Weibull proportional hazards model

A Weibull proportional hazards model was applied to evaluate the effects of 18 linear type traits on the functional length of productive life in Holstein cattle of Iran. Culling data and classification scores on 44,179 cows with first calving from 1996 to 2004 were used. The data included up to 55% of censored records. Length of productive life was defined as the number of days from first calving until last test day or censoring. The significance of each type trait was tested by a likelihood ratio test comparing the full model (with one particular type trait) with reduced models (without any of the type traits). Analyses were performed for each type trait one at a time which included as a covariate in the model. The strongest relationship between length of productive life and type traits were found for fore udder attachment, udder depth, udder cleft angularity and loin strength. Body traits except angularity had minimal effect on functional longevity. Some traits such as udder depth, rear legs side view and foot angle showed an intermediate optimum with respect to longevity and extreme scores of these traits increased risk of involuntary culling. Results of the present study showed that improvement of conformation traits, which is more associated with functional longevity, is a useful way to increase functional length of productive life.