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Wang Z.,Inner Mongolia Agricultural University | Wang R.,Inner Mongolia Agricultural University | Zhang W.,Inner Mongolia Agricultural University | Wang P.,Inner Mongolia Agricultural University | And 7 more authors.
Small Ruminant Research | Year: 2013

The objective of this study was to determine the genetic parameters and variance components of the economically important fleece traits staple fineness (SF), staple length (SL), fiber diameter (FD) and fiber length (FL) in yearling Inner Mongolia Cashmere goats (IMWC). Data collected in 2008-2011 from 5 Arbas Cashmere goat flocks were analyzed. Fixed effects were determined using a generalized linear model with least square means. Variance components and genetic parameters were determined using the restricted maximum likelihood method. By ignoring or including maternal additive genetic effects and maternal permanent environment effects, and considering whether direct additive genetic and maternal additive genetic effects were correlated or not, six different single-trait animal models were obtained. A log likelihood ratio test was conducted to choose the most appropriate model. Then, genetic correlations among fleece traits were obtained using the average information restricted maximum likelihood method with multi-trait models. Year of production and herd had highly significant influences on all fleece traits (P<0.01). Sex had highly significant influences on all fleece traits (P<0.01) except SF. Dam ages had a significant effect on FD (P<0.05), but was not related to other three traits. Type of birth had no significant effect on the fleece traits in this study (P>0.05). The log likelihood ratio test indicated that neither maternal additive genetic effects nor maternal permanent environment effects had a significant influence on the traits examined in this study. Direct additive heritabilities (hd2) were 0.27, 0.28, 0.34 and 0.17 for SF, SL, FD and FL, respectively, which is moderate to low. Direct additive genetic correlations were negative (-0.40) between SL and SF, but were positive (0.45) between SF and FD. Genetic correlations among the other traits were low, ranging from -0.17 to 0.12. The purpose of this study was to determine the genetics parameters of fleece traits to help improve the genetics of the Inner Mongolia Cashmere goats (IMWC). © 2012 Elsevier B.V.


Dai S.,Inner Mongolia Agricultural University | Wang C.,Inner Mongolia Agricultural University | Wang Z.,Inner Mongolia Agricultural University | Zhang Y.,Inner Mongolia Agricultural University | And 3 more authors.
Small Ruminant Research | Year: 2015

The objective of the present study was to evaluate the level of inbreeding and its effects on fleece traits in Inner Mongolia cashmere goats. Data of 36,901 records for 23 year (1990-2012), collected from the breeding flock of Inner Mongolia cashmere goats maintained at the Arbas stock farm, were used in the analyses. The traits studied were cashmere weight (CW), fiber length (FL), and fiber diameter (FD). The average inbreeding coefficient for the whole population was 4.01%, ranging from 0 to 35.94%. The mean rate of inbreeding was 0.32% per year for all animals. To investigate the effect of inbreeding on phenotypic values, genetic parameters and estimated breeding values, two different models including no measure of inbreeding and individual inbreeding coefficients Fi (linear and quadratic) were take into account. The results suggest that both cashmere weight and fiber length increased at low levels of inbreeding, but decreased when levels of inbreeding were higher than 12.5% and 4.4%, respectively, while FD became thinner with any increase of Fi. Moreover, the estimation of genetic parameters and breeding values for the studied characteristics was essentially unaffected by inclusion of Fi in the model. © 2015 Elsevier B.V.


Wang Z.,Key Laboratory of Animal Genetics Breeding and Reproduction | Wang Z.,Inner Mongolia Agricultural University | Liu Y.,Inner Mongolia Agricultural University | Wang R.,Inner Mongolia Agricultural University | And 3 more authors.
Small Ruminant Research | Year: 2015

The purpose of this study was to estimate the genetic parameters for fiber length (FL) and fiber diameter (FD) in Inner Mongolia White Cashmere goats (IMCGs) across age groups to determine whether genetic improvement of these fleece traits can be attained by early selection. Data on FL and FD were collected for analysis from 2008 to 2012 on IMCGs at the ages of 1-5 years. The 6851 repeat records of 3251 Inner Mongolia Cashmere goats were analyzed. These goats were descendants of 104 sires and 2172 dams. Genetic parameters for FL and FD in IMCGs from 1 to 5 years old were determined using the average Information Restricted Maximum Likelihood (AIREML) method in a multivariate animal model. Estimates of direct additive heritability for each fleece trait were significant across all age groups. The values were 0.19, 0.34, 0.21, 0.23 and 0.18 for FL, and 0.40, 0.39, 0.29, 0.38 and 0.29 for FD from 1 to 5 years old, respectively. The genetic correlation coefficients between FL and FD at each age ranged from 0.12 to 0.38, which were low to moderate. However, the genetic correlations for FL or FD were positive and high for all pairwise age comparisons, ranging from 0.75 to 0.99, and most values for a given trait between any two age classes exceeded 0.85. The high genetic correlations between yearlings and adults for each fleece trait inferred that selecting stocks at earlier ages may lead to genetic progress and improved fiber quality of IMCGs at later ages. © 2014 Elsevier B.V.


Wang Z.,Key Laboratory of Animal Genetics Breeding and Reproduction | Wang R.,Inner Mongolia Agricultural University | Li J.,Inner Mongolia Agricultural University | Zhang W.,Inner Mongolia Agricultural University | And 7 more authors.
Livestock Science | Year: 2014

The objective of this study was to estimate the parameters necessary to determine whether the genetic expression of fleece traits in Inner Mongolia Arbas cashmere goats was unified at different ages. Fleece traits, including fiber diameter (FD) and fiber length (FL), were measured between 2008 and 2012, as goats aged from 1 to 5 years old, and were modeled using repeatability and several multivariate models that varied in covariance structure. Bayesian information criteria were used to choose the most ideal model. In the preferred model, FD could be partitioned into yearlings and older goats, while FL could be partitioned into yearlings, 2 year olds, and older goats. The heritabilities of FD in yearlings and older goats were 0.35 and 0.27, respectively, and the genetic correlation between yearlings and older goats was 0.93. For FL, the estimates of heritability were 0.18, 0.38, and 0.29 within the 3 age groups. The genetic correlations were 0.94 for yearlings with 2 year olds and older goats and close to 1.00 for 2 year olds with older goats. These findings provide useful information for designing more ideal and effective breeding programs to improve fiber quality. © 2013 Elsevier B.V.


Zhang Y.,Inner Mongolia Agricultural University | Wang Z.,Key Laboratory of Animal Genetics Breeding and Reproduction | Lei H.,Inner Mongolia Agricultural University | Wang Z.,Inner Mongolia Agricultural University | And 7 more authors.
Small Ruminant Research | Year: 2014

Genetic parameters and genetic trends for staple length (SL), staple fineness (SF), fiber length (FL) and fiber diameter (FD) were estimated using 7798 repeat records of 4583 Inner Mongolia cashmere goats at different ages measured from 2008-2011. These goats were descendants of 110 sires and 2139 dams, born between 2003 and 2010 at the Inner Mongolia Arbas cashmere goat stock farm. Analyses were carried out by average information restricted maximum likelihood, fitting four single-trait repeatability animal models with various combinations of individual and maternal effects. The best model for each fleece trait was chosen after testing for improvement of the log-likelihood values. Genetic parameters were then estimated under the most appropriate model. Genetic trends were determined by regressing yearly estimated mean breeding values on year of birth. All the fleece traits were influenced by direct addictive genetic and individual permanent environment effects. Estimates of direct heritability for SL, SF, FL and FD were 0.30, 0.27, 0.18 and 0.32, respectively. Genetic correlations among the fleece traits (SL-SF and FL-SF) were negative and high (-0.50 and -0.48). For the other fleece traits (SL-FL and SF-FD), the genetic correlation was moderate and positive (0.26 and 0.31). The phenotypic correlation among all fleece traits was low, ranging from -0.22 to 0.23. Compared with other traits, fleece traits were not objective traits in previous breeding programs; they presented irregular changes across year of birth. Estimates of genetic parameters and analyses of genetic trends would be helpful for designing a breeding program for the genetic improvement of fleece traits in Inner Mongolia cashmere goats. © 2013.

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