In this study, 230 heads of Guilan native cows were phenotypically evaluated for 29 traits. Descriptive statistics were obtained per each level of sex (male and female), two levels of the genetic group (straight bred native and crossbred of the native by Holstein), and four levels of genetic groups × sex interaction. The results showed that the crossbred cows had dairy conformation while the type of Guilan native cows was meat-oriented. A distinctive feature of native cattle compared to cross and other breeds are the presence of withers, which is often seen in males and rarely in females. The phenotypic correlation coefficients of 25 attributes were calculated. There were 270 positive and 30 negative coefficients. Correlation coefficients ranged from -0.5 (thigh girth and fore teat length) to 0.95 (thigh girth and front leg length). The principal component analysis was performed to find the variables explaining the maximum variance in the main set of variables. The first and second components accounted for 57.17 and 11.53 percent of the total variance, respectively. Seven components accounted near to 90 percent of the total variance. Traits consist of width and environment of the chest, height in the hip area (rump), head length and hip to pin distance, height in stature area, depth and girth of abdominal, hip-width (hip to hip distance), front leg length, body length, and neck girth were more important for the first component, which is important in terms of bulk, size, length, width, height, and body growth as a result of meat production. Manuscript profile

The objective of the present study was to determine factors affecting body condition score (BCS) and its association with productive and reproductive performances in Holstein cows. Mixed model analysis was performed on monthly records of BCS from April 2006 to July 2012 comprising 34666 records from 3134 dairy cows in a large commercial dairy herd under arid climatic conditions of Isfahan in Iran. Body condition scores were recorded on a scale of 1 to 5. Fixed factors included in the final mixed model of analysis were evaluation year, parity and evaluation season and also year by parity, season by parity and year by season interaction effects. Average BCS in the dairy herd was 3.06 ± 0.77. The results showed that there was an increasing trend for BCS over the years from 2006 to 2012 (P<0.001). Also, the recording season of winter provided greater BCS than other seasons (P<0.001). Mean BCS increased from first to third parity but then declined thereafter (P<0.05). The correlation between BCS and milk yield was negative and varied from -0.23 to -0.13 over the parities. The correlation between BCS and fat percentage was low and changed from 0 (fourth and greater parities) to 0.08 (first and second parities). There were low to medium correlations (0.14 to 0.29) between BCS and protein percentage over the parities. The correlation estimates between BCS and days open, calving interval and number of inseminations per conception were low and positive, but the correlation between BCS and conception rate was negative over the parities. Manuscript profile

Recently genetic studies have been revolutionized by next generation sequencing (NGS) technology, and it is expected that the use of this technology will largely eliminate defects in the methods of association studies. The NGS technology is becoming the premier tool in genetics. However, at the moment the use of this method is limited especially in the livestock due to high cost and computational problems. But it is expected that the development of sequencing and computing technologies and reducing the cost will have significant impacts on the livestock health and production. This study reviews the literature on genetic association studies, NGS technologies and their application in animal breeding. Manuscript profile

The objective of the present study was to evaluate the effects of inbreeding on average daily gains and Kleiber ratios in Moghani sheep. Traits included average daily gain from birth to 3 months (ADG1), average daily gain from birth to 6 months (ADG2), average daily gain from 3 months to 6 months (ADG3), average daily gain from 3 months to 9 months (ADG4), average daily gain from 3 months to yearling (ADG5) and corresponding Kleiber ratios (KR1, KR2, KR3, KR4 and KR5, respectively). Data and pedigree information used in this study were collected at the Breeding Station of Moghani sheep during 1987-2005. All the animals were grouped into three classes according to the inbreeding coefficients obtained by their pedigree: the first class included non-inbred animals (F=0%); and the second and third classes included inbred animals (00.10, respectively). There were significant regression coefficients of ADG5 and KR5 on inbreeding of all lambs for changing 1% inbreeding (P<0.01). Indeed, there were significant regression coefficients of ADG3 (P<0.01) and KR3 (P<0.05) on inbreeding of twin-born lambs for a change of 1% in inbreeding. In addition, there were significant regression coefficients of ADG1 (P<0.05) and ADG5 (P<0.05) on inbreeding of male lambs and significant regression coefficient of ADG2 (P<0.05) on inbreeding of female lambs for a change of 1% in inbreeding. Effects of inbreeding on average daily gains and Kleiber ratios in Moghani sheep was not very pronounced in the flock. Planned matings are, however, suggested to avoid accumulation of inbreeding and appearance of its deleterious effects. Manuscript profile

The objective of this study was to evaluate non-genetic factors affecting longevity and survival of Guilan sheep from birth to yearling. Longevity and survival records of 41037 lambs born from 496 rams and 10256 ewes of Guilan sheep were analyzed using linear and Weibull models. Results indicated that the overall mean of longevity was 1260.84 days. The fixed effects of flock, dam age, sex, year and month of birth and interaction between dam age-sex had significant effects on longevity (P<0.05). But birth type, birth weight and interactions of sex-birth type and dam age-birth type had no significant effect on longevity (P>0.05). Male lambs had lower survival and greater hazard ratio compared with female lambs. Lambs which born in recent years and last months of year had greater hazard ratios and lower survival in the period from birth to 2-months and birth to yearling. Lambs which born in early months of year had greater survival and lower hazard ratio than those birth to 3, 6 and 9 months of age. Although twin lambs had lower survival and greater hazard from birth to 2 and 3 months of age periods, difference of single and twin lambs was not significant in other time periods. In conclusion, linear and non-linear models can be used to study the survival of lambs and it’s possible to improve this important item through modifying non-genetic factors. Manuscript profile

The objective of this study was to estimate variance components and genetic parameters for growth curve parameters in Shall sheep. Studied traits were parameters of Brody growth model which included A (asymptotic mature weight), B (initial animal weight) and K (maturation rate). The data set and pedigree information used in this study were obtained from the Animal Breeding Center of Iran and comprised 4020 growth curve parameters of lambs from birth to 400 days of age during 1982 to 2012. Marginal posterior distributions of parameters and variance components were estimated using TM program. The Gibbs sampler was run 300000 rounds and the first 60000 rounds were discarded as a burn-in period. Posterior mean estimates of direct heritabilities for A, B and K were 0.13, 0.15 and 0.19, respectively. Estimates of direct genetic correlation between growth curve parameters were 0.41, -0.30 and -0.31 between A-B, A-K and B-K, respectively. Residual correlations between growth curve parameters varied from -0.57 (between A-K) to 0.62 (between A-B). Also, phenotypic correlations between growth curve parameters varied from -0.48 (between B-K) to 0.30 (between A-B). The low estimates of heritability obtained in this study implies that although genetic selection could be partially affected on the growth curve parameters, much of the improvement in these parameters could be attained by improvement of production environment rather than genetic selection in this breed of sheep. Manuscript profile