فهرست مقالات non-genetic factors

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  1 - Growth Modeling and Genetic Analysis on Growth Traits of Sirohi Goat under Field Conditions
  ل. گاوتام ر.آ. کومار ناگدا ه. اشرف وایز
  The data on 6772 growth records of Sirohi goats maintained at All India Coordinated Research Projecton Sirohi goat at Livestock Research Station, Vallabhnagar, Udaipur, India, and recorded between 2004 and 2016, were analysed to study the growth related traits and their چکیده کامل

  The data on 6772 growth records of Sirohi goats maintained at All India Coordinated Research Projecton Sirohi goat at Livestock Research Station, Vallabhnagar, Udaipur, India, and recorded between 2004 and 2016, were analysed to study the growth related traits and their genetic control. The overall least squares means of body weight at birth, W3M, W6M, W9M, W12M, were 2.34 ± 0.03, 12.44 ± 0.19, 16.31 ± 0.22, 20.08 ± 0.47 and 25.09 ± 0.40 kg, respectively while least-squares means for pre- and post-weaning average daily gains were 113.66 ± 2.15 and 46.17 ± 0.94 g/day, respectively. The various non-genetic factors exhibited variable effects on the growth traits at different phases of age. Cluster and period of birth had significant effect on all growth traits. Season of birth had significant effect except birth weight. Summer born kids heavier and higher body weight and pre- and post-weaning gains than winter and rainy season born kids. Males had a higher weight and higher daily gain than females at almost all stages of growth. Kids of primiparous dams had significantly lower birth weight as compared to multiparous dams’ kids. Single born kids had a distinct advantage over those born in multiple births at all stages of growth. The regression on dam’s weight at kidding were positive significant for all stages of growth traits. The heritability estimates of all body weights and weight gains at different stages of growth were moderate (0.16-0.28), except for post-weaning average daily gain, which had low heritability (0.07±0.01). The phenotypic and genetic correlations among the different growth traits were positive and high, except for phenotypic correlation between pre- and post-weaning gains which was negative. Four non-linear growth models, viz., Gompertz, Brody, Logistic and Von Bertalanffy were used to describe the growth pattern in Sirohi kids based on the growth parameters. The highest R2 value and lowest mean absolute error (MAE), akaike’s information criteria (AIC) and mean absolute percentage error (MAPE) values were observed in Brody model. پرونده مقاله
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  2 - Study of Factors Affecting Longevity and Survival of Iranian Guilan Sheep Using Linear and Non-Linear Models
  م. نداف فهمیده ن. قوی حسین زاده م. گلشنی
  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 Weibul چکیده کامل

  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. پرونده مقاله