NAAS Score 2020

                   5.36

UserOnline

Free counters!

Previous Next

Estimation of Genetic Parameters of Growth Traits of Khari Goat Kids (Capra hircus L.) in Nawalparasi, Nepal

N. Bhattarai M. R. Kolachhapati N. R. Devkota U. C. Thakur S. P. Neopane
Vol 7(1), 80-89
DOI- http://dx.doi.org/10.5455/ijlr.20161218124223

Genetic parameters of growth traits of kids are important in improving their genetic make-up with respect to production and productivity. A study was carried out mainly aiming at estimating genetic parameters of growth traits of Khari goat kids in Nawalparasi, Nepal from February, 2012 to January 2015. Altogether 1260 kids of Khari goat born from 1004 adult does mated with 53 breeding bucks were considered for estimating the heritability (h2) of body weight (at birth, pre-weaning, weaning, six months, nine months, twelve months and fifteen months age), genetic and phenotypic correlation among body weight of kids at different stage of growth of kids. Least Square Mixed Model and Maximum Likelihood Computer Program: PC-2 developed by Walter R. Harvey. Findings revealed that the h2 estimates of body weights were within the range of 0.37±0.12 (at birth) and 0.46±0.14 (at six months), respectively. Similarly, genetic correlation (rg) among the body weight of kids at different stage of growth was ranged from 0.61 (between birth and pre-weaning) to 0.96 (between nine and twelve month). Whereas, phenotypic correlation (rp) among the body weight of kids at different stage of growth was determined within the range of 0.56 (between pre-weaning and fifteen months) and 0.94 (between twelve and fifteen month). Moderate to high h2 estimates of weight traits in this study indicated a relatively greater contribution of additive genetic variance and high potentiality for improving productivity of kids through intense selection. Whereas, significantly strong positive genetic and phenotypic association (p<0.001) between the weight of kids at earlier and later age indicated that these traits could be the most important and effective selection criteria for achieving higher body weight at later age of kids.


Keywords : Weight Traits Heritability Genetic and Phenotypic Correlation Khari Goats

Introduction

Livestock farming contributes about 26.8% to total Agricultural Gross Domestic Product (AGDP) and about 11% to total Gross Domestic Product (GDP) as reported by MOAD (2015). Cattle, buffalo, sheep, goat, pig and poultry are the major livestock species widely being reared in Nepal. Goat farming is being the most popular means of self employment among the youths in the country. Current statistics regarding to goat population indicated that there are more than 10.25 million heads of goats in the country (MOAD, 2015). Nepalese hill goat that is also popular as Khari or Aule is one of the most popular for its productivity, prolificacy, twinning ability and adaptively over the other three prominent indigenous breeds viz. Chyangra (in mountains), Sinhal (in high hills), and Terai (in Terai) as reported by Kharel and Neopane (1998). The rate of increment in goat population during last 15 years (2000/01 to 2014/15) was reported 3.65 percent per year contributing about 20.1% to the total meat production in the country (MOAD, 2015). Genetic parameters of growth traits of kids are important in improving their genetic make-up in relation to increased production and productivity of goats. Thiruvenkadan et al., 2009 studied the heritability of body weight tended to increase with increasing age from birth to six months and then decreased. Weight at birth was of low heritability (0.062 ± 0.069) and the heritability’s of the body weights at three, six, nine and twelve months of age were medium to highly heritable. The heritability estimates for Tellicherry kids observed are in accordance with earlier reports (Acharya & Malik, 1971; Bhadula & Bhat, 1980; Mandal et al., 2003). Correlation analysis measures the degree and direction of association between two variables but could not explain the cause and effect relationship between traits (Gomez and Gomez 1984; Mead et al., 1996). Phenotypic correlation between traits is the gross correlation that includes the environmental and genetic portion of covariance (Lasley, 1963).

Very few studies on estimating genetic parameters of growth traits of Khari goat kids have been carried out in Nepal that needs to be redefined and updated. Neopane (1997) and Parajuli (2012) estimated the genetic parameters of Nepalese hill goats mainly focusing to heritability, genetic and phenotypic correlation and reported the low to moderate heritability of growth traits. Present study has been carried out with the main objective of determining the heritability estimates birth weight (BWT), pre-weaning weight (PWT), weaning weight (WWT), six months weight (SWT), nine months weight (NWT), twelve months weight (TWT) and fifteen months weight (FWT) of Khari goat kids. In addition, the study had aimed at determining the genetic and phenotypic correlation among these traits.

Materials and Methods

Study Area and Duration

This study was conducted in the village goat herds of Deurali VDC, Nawalparasi, Nepal from February, 2012 to January 2015 covering two agro-ecological domains viz. Inner Terai (lower altitude, ranging 300-700 masl) and hill (upper altitude, ranging 700-1100 masl).

Study Animals and Study Design

Altogether 1260 kids born from 1004 adult does mated to 53 breeding bucks were selected randomly from the participant households of research sites. The participants were identified based on their willingness to participate in the research and flock size (>5 heads) they own. The structural summary of the data sets under this study is presented in Table 1.

Table 1: Structural Summary of Data Sets Taken Under the Study

Non-genetic factors and their sub-classes No. of observation for kids traits No. of observation for dam’s traits
Altitude
Lower 188 134
Upper 1072 870
Color
Black 460 300
Black and white 45 25
Brown 537 525
Mixed 64 40
White 154 114
Season of Conception
Spring 98 76
Rainy 418 338
Autumn 722 574
Winter 22 16
Season of Kidding
Spring 548
Rainy 26
Autumn 316
Winter 370
Parity
Early (1st and 2nd) 424 378
Middle (3rd to 6th) 634 481
Late (> 7th ) 202 145
Size of Dams
Small 152
Medium 902
Large 206
Sex
Male 696
Female 564
Birth Type
Single 754
Twins 472
Triplets 34
Total Breeding Bucks = 53 Kids = 1260 Dams = 1004

Data Collection

Data regarding to weight traits of kids at different stages of growth were directly measured regularly starting from the birth to fifteen months age of kids using weigh balance on monthly basis.

Traits under Consideration

Body weight traits of Khari goat kids at different stages of growth including birth, pre-weaning, weaning, six months, nine months, twelve months and fifteen months age were considered for estimating their genetic parameters. The traits under consideration of present study are described in Table 2.

Table 2: Body Weight Traits of khari Goat Kids at Different Stage of Growth and Their Recording Procedure

Traits Recording procedure
Birth weight (kg) Live weight of individual kids taken within 24 hours after birth.
Pre-weaning weight (kg) Live weight of kids taken at the age of 2 months from kidding.
Weaning weight (kg) Live weight of kids taken at the age of 4 months from kidding.
Six months weight (kg) Live weight of kids taken at the age of 6 months from kidding.
Nine months weight (kg) Live weight of kids taken at the age of 9 months from kidding.
Twelve months weight (kg) Live weight of kids taken at the age of 1 year from kidding.
Fifteen months weight (kg) Live weight of kids taken at the age of 15 months from kidding.

Data Analysis

Collected data were analyzed by Least Square Mixed Model and Maximum Likelihood Computer Program (LSMMML PC-2)’ (Harvey, 1990). Least Square mean (LSM) and standard error of the mean (SEM) of heritability of weight traits of kids at different stages of growth were determined using the following statistical model given by Henderson (1953). Sire was taken as random (genetic) factor to estimate the genetic parameters (heritability estimates) of the traits assessing the genotypic and phenotypic correlation traits considered.

Yij= μ+ Si +eij

Where, Yij = Heritability estimates of the body weight traits of kids at different stages of growth.

μ = the overall population mean

si= random effect of ith Sire (i = 1, 2, …………53)

eij = random error or residual effect- is the random (residual) element assumed to be normally & independently distributed.

The terminology adopted for the discussion of the magnitude of various types of correlations (absolute values) was low = 0.00 to 0.25, moderate = 0.26 to 0.50, high = 0.51 to 0.75 and very high = 0.76 to 1.0 as suggested by Kuthu et al., 2015.

Results and Discussion

Heritability Estimates

Results of this study revealed that the heritability estimate of body weight was observed to be 0.37 at birth, 0.42 at both pre-weaning and weaning, 0.46 at six months, 0.44 at nine months, 0.40 at twelve months and 0.39 at fifteen months age of Khari goat kids (Table 3). Moderate to high heritability of the weight traits of Khari goat kids indicated a relatively large contribution of additive genetic variance and potentiality for improving body weight in goats by selection. Similarly, increasing heritability of body weights of kids at the later stages of growth indicated that environmental factors have more influence on birth weight than on the weights achieved later on the later stage of growth. Heritability estimates for weight traits at different stages of growth of Khari goat observed in present study were higher than those usually found in literature (Neopane, 1997; Parajuli, 2012) for this breed of goat.

Table 3: Heritability Estimates of Weight Traits of Khari Goat Kids at Different Stage of Growth in Nawalparasi, Nepal

Traits Heritability Estimates
Birth weight 0.37±0.12
Pre-weaning 0.42±0.13
Weaning 0.42±0.13
Six months 0.46±0.14
Nine months 0.44±0.13
Twelve months 0.40±0.12
Fifteen months 0.39±0.12

*Significant at 5% level (i.e. p<0.05); **Significant at 1% level (i.e. p<0.01); ***Significant at 0.1% level (i.e. p<0.001)

Hasan et al., 2014reported the heritability estimates for birth, weaning, six months, twelve months, and eighteen months weight as 0.54±0.12; 0.35±0.07; 0.37±0.09; 0.68±0.16 and 0.63±0.19, respectively that were in line with the findings of present study. Bosso et al., 2007 working in West African Dwarf goats and Al-Shorepy et al., 2002 working in Emirati goat reported the heritability estimates of birth weight as 0.50 and 0.39, respectively which had confirmed the reliability of present findings. Zhang et al., 2009 and Al-Saef (2013) also reported the heritability estimates of birth weight in Syrian Damascus goat and Boer goat as 0.41 and 0.30, respectively. The increased heritability estimate of weight traits as the age increased from birth to weaning indicated that gain due to selection in weights at later age could be obtained, as compared to that of earlier age. In the contrary, high estimate of heritability for birth weight of Aradi goat, Damascus and their crossbreed kids was reported by Al-Saef (2013). Heritability estimates obtained for weaning weight in present study was 0.42 which was higher than the finding of Hasan et al., 2014 and Zhang et al.,2009 who reported a lower value of heritability estimates for the same trait in Ettawa Grade goats (0.35) and Boer goats (0.09 – 0.23). However, heritability estimates for weaning weight of Khari goats in this study was within the range of published values (Al-Shorepy et al., 2002; Boujenane & El-Hazzab, 2008; Al-Saef, 2013). Estimation heritability of weaning weight was reported in Emirati and Syrian Damascus goat to be 0.45 and 0.21 respectively (Al-Shorepy et al., 2002; Al-Saef, 2013). Boujenane & El-Hazzab et al., 2008 obtained heritability for weaning weight used single-trait analysis with range of 0.18-0.65. It has been reported that genetic improvement for weaning weight have been attributed to affecting fertility, prolificacy, kid survival to weaning and dam viability from mating to weaning (Zhang et al., 2009).

Heritability estimate of six month weight of Khari goat kids in present study was recorded to be 0.46 (Table 3). Hasan et al., 2014, Al Saef, 2013 and Boujenane & El-Hazzab , 2008, estimated the lower value of heritability of six months weight than the findings of present study in Etawa Grade goat (0.37), Draa goats (0.11-0.23) and in Syrian Damascus goat (0.36). The variations in these literatures may be due to the differences in goat breed, environment and management. Additionally, statistical methods, data structure and sampling error as reported by Zhang et al., 2009. The heritability estimates for twelve months weight of Khari goat kids in this study was determined to be 0.40 (Table 3). In contrary, Hasan et al., 2014 and Bosso et al., 2007 reported significantly higher value of heritability estimates for twelve months weight of Etawa Grade goats (0.68) and West African Dwarf goats (0.73). However, results of present study were in line with the findings obtained by several authors Zhang et al., 2009 on Boer goat, Ozcana et al., 2005 on Turkish Merino sheep, Safari et al., 2005 on sheep and Gizawa et al., 2007 on Menz sheep. Moderately high heritability estimates of body weight traits at different stages of growth in present study suggested that selection on the basis of individual performance will be effective in achieving increased genetic gain in these traits. Besides, Khari goat not being subjected to intense selection process might be the reason for higher variation and consequently higher heritability.

Genetic Correlation

Genetic correlation among the weight traits at different stages of growth of Khari goat kids is presented in Table 4. Accordingly, genetic correlations between all body weight traits in this study ranged from 0.61 (between birth and pre-weaning) to 0.96 (between nine and twelve months weight). Hasan et al., 2014 reported the genetic correlations between all body weight traits in this study ranged from 0.03 for birth weight and twelve months weight and 0.87 for twelve months and eighteen months weight of Etawa Grade goat kids. Similarly, genetic correlations among weight measurements were low to high and ranged from 0.19 to 0.92 (Bosso et al., 2007; Zhang et al., 2008; Wang et al., 2011). In disagreement with the findings of present study, Hasan et al., 2014, Bosso et al., 2007 and Al-Saef, 2013 reported low genetic correlation of birth weight with the weight traits at later ages ranging from 0.03 to 0.35. Boujenane & El-Hazzab (2008) reported that birth had higher genetic correlation on Draa goats which was within the range of the results of present study.

Table 4: Genetic Correlation between the Weight Traits of Khari Goat Kids at Different Stage of Growth in Nawalparasi, Nepal

Body Weight at Body Weight at
Birth Pre-weaning Weaning Six months Nine months Twelve months Fifteen months
Birth 0.61** 0.71** 0.72** 0.76*** 0.79*** 0.78***
Pre-weaning 0.81*** 0.80*** 0.75*** 0.65** 0.55*
Weaning 0.95*** 0.86*** 0.78*** 0.68**
Six months 0.93*** 0.85*** 0.76***
Nine months 0.96*** 0.85***
Twelve months 0.95***
Fifteen months

*Significant at 5% level (i.e. p<0.05); **Significant at 1% level (i.e. p<0.01); ***Significant at 0.1% level (i.e. p<0.001)

The estimate of genetic correlation of weaning weight with six, nine and twelve months weight in this study was high (0.95, 0.86 and 0.78, respectively) and this implied that weaning weight is a good indicator of subsequent development of the kid as pointed by Hasan (2014). The genetic correlation coefficients in this study also correspond well with Bosso et al., 2007 who reported genetic correlation for weaning weight and yearling weight for West African Dwarf goat as 0.74. The reason of different estimates could be due to the fact that all estimates depend on the models that were utilized as well as the random factors (Hasan et al., 2014 and Zishiri et al., 2009). The high and positive genetic correlations of weaning weight with six months, nine months and twelve months weight of Khari goat kids in this study indicated that they are all being controlled by similar genes and thus selection for any one of these traits would lead to positive changes in the other as reported by Hasan et al., 2014 and Boujenane & El-Hazzab (2008).

Phenotypic Correlation

Phenotypic correlation among the weight traits at different stages of growth of Khari goat kids is presented in Table 5. Accordingly, phenotypic correlations among all the body weight traits in this study ranged from 0.56 (between pre-weaning and fifteen months) to 0.94 (twelve months and fifteen months body weight). Hasan et al., 2014 working in Etawa Grade goats reported the phenotypic correlations ranging from 0.08 between birth weight and twelve months weight to 0.93 between twelve months weight and eighteen months weight of kids. The phenotypic correlations between all traits found same trend as the genetic correlations in accordance with previous studies in different goat breeds as reported by Al-Shorepy et al., 2002, Xu et al., 2005, Han et al., 2005, and Maxa et al., 2006. Phenotypic correlation between birth weight, one month weight and three months weight of kids ranging from 0.45 to 0.99 (Al-Shorepy et al., 2002) which was within the range of present findings. Snyman (2012) reported that estimates of direct heritability increased from 0.12 for eight months, to 0.34 for twelve months and 0.58 for sixteen months in Angora goat kids and young goats, which was in accordance with the findings of present study. Besides, findings of this study were also in accordance with estimates obtained with sheep (Snyman et al., 1995; Safari & Fogarty, 2003). Strong positive association among the weight traits of kids at all stages of growth in this study indicated that selection for increased weight at earlier age will result in increased weight of kids at later stage of growth as reported by Bosso et al., 2002.

Table 5: Phenotypic Correlation between the Weight Traits of Khari Goat Kids at Different Stage of Growth in Nawalparasi, Nepal

Body Weight at Body Weight at
Birth Pre-weaning Weaning Six months Nine months Twelve months Fifteen months
Birth
Pre-weaning 0.64**
Weaning 0.67** 0.80***
Six months 0.68** 0.75*** 0.91***
Nine months 0.71** 0.69** 0.81*** 0.92***
Twelve months 0.70** 0.62** 0.75*** 0.83*** 0.94***
Fifteen months 0.72** 0.56* 0.66** 0.76*** 0.86*** 0.94***

*Significant at 5% level (i.e. p<0.05); **Significant at 1% level (i.e. p<0.01); ***Significant at 0.1% level (i.e. p<0.001)

Conclusion

Since the moderate to high heritability estimates of weight traits are supported with significantly strong positive genetic and phenotypic association among the traits recorded at different stages of growth of kids, it can be concluded that there is great scope of bringing improvement in the genetic make-up of existing population of Nepalese hill goats, Khari through intense and effective selection practice. Significantly high positive genetic and phenotypic association between weaning weight and the weight of kids at proceeding age suggested that this trait could be the effective criteria for selecting the kids for better performance in later stage of growth reducing the time to wait for the weight of kids at later age. Similarly, significantly strong positive genetic and phenotypic association between six and twelve months age of kids indicated that this trait is more effective to consider in selection program for increased finish weight of kids at twelve months age.

Acknowledgements

The authors are grateful to Bhola Shankar Shrestha, Yamuna Kumar Shrestha and Sunita Sanjyal, NARC for their everlasting cooperation while preparing this manuscript. Authors are equally grateful to Prof. M.P. Sharma and the entire team of the Department of Animal Breeding and Biotechnology, Agriculture and Forestry for their constant encouragement during the study period. Sincere thanks and heartfelt gratitude also goes to University Grant Commission (UGC), Sanothimi, Bhaktapur for the partial funding assistance while conducting present study in the field. Authors are also grateful to the farmers of commercial and smallholder farmers of Deurali VDC of Nawalparasi district. Support from the Dean, FAVF; Director, DOREX, colleagues and administrative officials from Agriculture and Forestry University, Rampur, Chitwan are highly valued for their continuous cooperation during the study period.

References

  1. Acharya, R.M. and R.C. Malik. 1971. Genetic and phenotypic parameters for pre- and post-weaning body weight in Nali and Lohi and their crosses with Nellore and Mandya. Indian J. Anim. Sci. 41, 1126-1129.
  2. Al-Saef. 2013. Genetic and phenotypic parameters of body weights in Saudi Arabi goat and their crosses with Syrian Damascus goat. Small Rumin. Res. 112: 35-38. htp:// dx.doi.org/10.1016/j.smallrumres.2012.12.021
  3. Al-Shorepy, S. A., G. A. Alhadrami., and K. Abdulwahab. 2002. Genetic and phenotypic parameters for early growth traits in Emirati goat. Small Rumin. Res. 45: 217-223. htp:// dx.doi.org/10.1016/S0921-4488(02)00110-4
  4. Bhadula, S. K. and P. N. Bhat. 1980. Genetic and non-genetic factors affecting body weights in Muzaffarnagari sheep and their half breeds. Indian J. Anim. Sci. 50, 852-856.
  5. Bosso, N. A., M. F. Cisse., E. H. van der Waaij, A. Fall, & J. A. M. van Arendonk. 2007. Genetic and phenotypic parameters of body weight in West African Dwarf goat and Djallonke sheep. Small Ruminant Research. 67: 271-278. htp://dx.doi. org/10.1016/j.smallrumres.2005.11.001
  6. Boujenane, I and A. El Hazzab. 2008. Genetic parameters for direct and maternal effect on body weights of Draa goats. Small Ruminant Research. 80: 16-21. htp://dx.doi.org/10.1016/j.sm allrumres.2008.07.026
  7. Gizaw, S., S. Lemma, H. Komen and J. A. M. van Arendonk. 2007. Estimates of genetic parameters and genetic trend for live weight and fleece traits in Menz sheep. Small Rumin. Res. 70: 145-153.
  8. Gomez, K.A. and A.A. Gomez. 1984. Statistical Procedures for Agricultural Research. 2nd edition. John Wiley and Sons, Singapore. pp. 364-420.
  9. Han, W. J., T. Feng., J. J. An and Y. L. Chen. 2005. Analysis on comparison of body weight for different hybrid weaned lamb. Acta Ecologiae Animalis Domastici. 26: 43-45.
  10. Harvey, W.R.1990. Users’ Guide for LSMLMW and MIXMDL. PC-2 Version. Mixed Model Least Squares and Maximum Likelihood Computer Program.
  11. Hasan, F., J. Jakaria and A. Gunawan. 2014. Genetic and phenotypic parameters of body weight in Ettawa grade goats. Media Peternakan, 37(1), 8–16. http://doi.org/10.5398/medpet.2014.37.1.8
  12. Kharel, M. and S.P. Neopane. 1998. Goat genetic resources. In: Proceedings of the 1st National Workshop on Animal Genetic Resources Conservation and Genetic Improvement of Domesticated Animals in Nepal. (Editor: JNB Shrestha). Nepal Agricultural Research Council (NARC) from 11 to 13 April 1994, Pp 48-54, Kathmandu, P O Box 5459, Nepal.
  13. Kuthu Z. H., K. Javed, N. Ahmad, A. Hussain and S. A. Khan. 2015. Genetic evaluation of post-weaning growth traits in Teddy goats. J Dairy Vet Anim Res 2(2): 00032. DOI: 10.15406/jdvar.2015.02.00032.
  14. Lasley, J. F. 1963. Genetics of Livestock Improvement. Printice-Hall of India Pvt. Ltd, New Delhi. pp. 69-71.
  15. Mandal, A., K. P. Pant, P. K. Nandy, P.K. Rout and R. Roy. 2003. Genetic analysis of growth traits in Muzaffarnagari sheep. Trop. Anim. Hlth. Prod. 35, 271-284.
  16. Mead, R., R.N. Curnow, and A.M. Hasted. 1996. Statistical Methods in Agriculture and Experimental Biology. 2nd Edition. Champman and Hall, London. Pp. 161-211.
  17. MOAD. 2015. Selected indicators of Nepalese Agriculture and Population. Agri-business promotion and Statistics Division (ABPSD), Ministry of Agriculture Development (MOAD), Singh Durbar, Kathmandu, Nepal.
  18. Neopane, S.P. 1997. Genetics of productive traits in a Nepalese Hill goat flock. Ph.D. Thesis. University of London, UK. 278p.
  19. Ozcana, M., B. Ekiza., A. Yilmaza and A. Ceyhanb. 2005. Genetic parameter estimates for lamb growth traits and greasy fleece weight at first shearing in Turkish Merino sheep. Small Rumin. Res. 56: 215-222. http://dx.doi.org/10.1016/ j.smallrumres.2004.06.00
  20. Parajuli, A.K. 2012. Morphometric Characterization and Performance Evaluation of Hill Goat in Mid Hills of Nawalparasi District of Nepal. Thesis MSc. Institute of Agriculture and Animal Sciences, Rampur, Chitwan. 114p.
  21. Safari, A. and N.M. Fogarty. 2003. Genetic parameters for sheep production traits. Estimates from the literature. NSW Agriculture, Orange Agricultural Institute, Orange, NSW, 2800, Australia. Australian Sheep Industry Cooperative Research Centre. pp. 13-21.
  22. Snyman, M.A., Erasmus, G.J., Van Wyk, J.B. & Olivier, J.J., 1995. Direct and maternal (co)variance components and heritability estimates for body weight at different ages and fleece traits in Afrino sheep. Livest. Prod. Sci. 44, 229-235.
  23. Snyman. 2012. Genetic parameters for body weight of South African Angora kids and young goats. Grootfontein Agric 12 (1): 24.
  24. Thiruvenkadan, A. K., M. Murugan, K. Karunanithi, J. Muralidharan, and K. Chinnamani. 2009. Genetic and non-genetic factors affecting body weight in Tellicherry goats. South African Journal of Animal Sciences, 39(SUPPL. 1), 107–111.
  25. Wang, D. H., G. Y. Xu., D. J. Wu, & Z. H. Liu. 2011. Characteristic and production performance of Tianfu goat, a new breed population. Small Rumin. Res. 95: 88-91. htp:// dx.doi.org/10.1016/j.smallrumres.2010.10.010
  26. Xu, T. S., D. J. Wang., X. L. Liu., G. Y. Hou., W. L. Xia, & X. Z. Huang. 2005 .Genetic parameters and trends of milk and fat yield in Holstein’s dairy cattle of West Province of Iran. Int. J. Dairy. Sci. 6: 142-14.
  27. Zhang C.Y., Y. Zhang, D.Q. Xu, X. Li, J. Su, and L.G. Yang. 2009. Genetic and phenotypic parameter estimates for growth traits in Boer goat. Livest. Sci. 124: 66-71.
  28. Zhang, C.Y., L.G. Yang, Z. Shen. 2008. Variance components and genetic parameters for weight and size at birth in the Boer goat. Livest. Sci. 115, 73–79.
  29. Zishiri, O. T., S. W. P. Cloete, J. J. Olivier & K. Dzama. 2010. Genetic trends in South African terminal sire sheep breeds. S. Afr. J. Anim. Sci. 1: 450-458.
Full Text Read : 1433 Downloads : 246
Previous Next

Open Access Policy

Close