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Estimation of Genetic Parameters for Reproduction Traits in Munjal Sheep

Umeel Yadav Z. S. Malik D. S. Dalal S. P. Dahiya C. S. Patil
Vol 8(1), 195-201
DOI- http://dx.doi.org/10.5455/ijlr.20170902025155

Estimates of genetic parameters are important to determine the selection criterion and future breeding strategies. Munjal is one of the heaviest breed of sheep and is popular among farmers for faster growth rate and efficient reproduction. The data of reproduction traits of 287 Munjal sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar for 16 years (2001-2016) were utilized to estimate the genetic parameters. The mixed linear model used for analysis included the sire as a random effect and period of birth and dam’s age at lambing as fixed effects. Heritability and genetic correlations for different traits were estimated by paternal half-sib correlation method using sire components of variance and covariance. All the reproduction traits under study viz., age at first service (AFS), weight at first service (WFS), age at first lambing (AFL), weight at first lambing (WFL) and first lambing interval (FLI) were significantly affected by period of birth. However, effect of dam’s age at lambing was non-significant on all traits. The overall least squares mean for AFS, WFS, AFL, WFL and FLI were estimated as 563.08±14.43days, 29.06±0.16 kg, 713.48±14.02 days, 31.30±0.16 kg and 351.82±1.12 days, respectively. Heritability estimates for AFS, WFS, AFL, WFL and FLI were obtained 0.19±0.12, 0.24±0.15, 0.17±0.10, 0.27±0.15 and 0.05±0.01, respectively. The genetic correlation of AFS with AFL (0.96±0.01) and WFS with WFL (0.94±0.03) was high and positive indicating that ewes in good body condition at service maintaining it after lambing. Low estimates of heritability for reproduction traits indicated that these traits have low additive genetic variance and mostly influenced by environment. So, these traits can be improved by better managemental practices.


Keywords : Correlation Heritability Munjal Sheep Reproduction Traits

Introduction

Sheep farming is an important component of rural economy particularly in the arid, semi-arid and mountainous areas of the country due to its multi-purpose utility for meat, wool, skin, milk and manure. Sheep are capable of living in all kind of environment and thrive well in hot and arid regions. The sheep is known for its adaptability to the harsh environment and potential for high meat production (Gowane et al., 2010). Munjal sheep is large in size, tall, rectangular and popular among the farmers of Haryana, Punjab and Rajasthan for their heavy weight. It has long head with Roman nose and narrow forehead.  Face is generally tan or brown in colour, which may extend up to middle of neck.

Development of breeding strategies and effective genetic improvement programme require knowledge of the genetic variation among important traits and accurate estimates of heritability and genetic correlations. Heritability estimates are useful for construction of selection indices, prediction of genetic response to selection and for deciding how much one can rely upon individual’s own phenotype for selection. The extent and direction of genetic correlations are essential to evaluate direct and correlated responses and net genetic gain, when simultaneous selection for several traits is practiced. The literature is dotted with conflicting and sporadic reports regarding genetic parameters of reproduction traits in sheep (Dey and Poonia (2005) in Nali sheep, Baber and Javed (2009) in Lohi sheep, Qureshi et al. (2010) in Kajli sheep, Chandar (2012) in Magra sheep and Gowane et al. (2014) in Malpura sheep and lalit et al. (2016) in Harnali sheep) but negligible research work is available for Munjal sheep. Therefore, the present investigation was carried out to estimate the genetic parameters of reproduction traits in Munjal sheep.

Materials and Methods

The data were collected over a period of 16 years (2001-2016)  pertaining to reproduction traits of 287 Munjal sheep maintained at Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar. The information were recorded on five reproduction traits namely age at first service (AFS), weight at first service (WFS), age at first lambing (AFL), weight at first lambing (WFL) and first lambing interval (FLI). The data were classified according to year of birth and age of dam at lambing to study the effect of these factors on traits under study. Whole duration of 16 years were divided into 8 groups each having two year duration on the basis of years of birth. For studying the effect of age of dam at lambing, the data were classified into different age groups (≤ 36 month, 36-48 month, 48 to 60 month, 60 to 72 month and ˃72 month of dam’s age at lambing). The effect of non-genetic factors viz. period of birth and dam’s age at lambing on various traits was studied by least squares technique by Harvey (1990) using the following mixed model-

YIJKLM = µ + SI + PJ + DL + EIJKLM

Where, Yijklm is observation on mth animal belonging to lthage group of dam, jth period of birth and ith sire. m is the overall mean; Si is the random effect of ith sire (i= 1 to 27); Pj is the fixed effect of jth period of birth (j = 1 to 8); Dl is the fixed effect of lthage group of dam (l = 1, 2,…5.); eijklm is the random error associated with each observation and assumed to be normality and independently distributed with mean zero and variance σ2e . Modified Duncan’s multiple range test was used for comparing sub group means by Kramer (1957).

Heritability estimates for different reproduction traits were obtained from sire component of variances using paternal half-sib correlation method. The standard errors of heritability estimates were obtained using the formula given by Swiger et al. (1964). Genetic correlations among different traits were calculated from sire components of variances and co-variances and standard errors were estimated using the formula given by Robertson (1959). Phenotypic correlations among various traits were calculated from total variances and covariances and their standard error were computed using the formula given by Snedecor and Cocharan (1968).

Results and Discussion

The analysis of variance and least squares means along with standard error for the reproduction traits are presented in Table 1 and 2 respectively.

Table 1: Analysis of variance for reproduction traits in Munjal sheep   

Source of Variation D.F. Mean Sum of Squares
AFS WFS AFL WFL FLI
Sire 26 14374.05 2.88 13739.03 2.905 106.607
Period of birth 7 61092.67** 45.45** 63398.65** 45.53** 10044.74**
Dam’s age at lambing 5 873.54 1.28 1579.65 1.7 287.19
Error 248 1490.14 2.08 1670.73 2.09 195.42

 ** Significant at P≤0.01

Effect of Non-Genetic Factors

The period of birth had significant (P≤0.01) effect but the dam’s age at lambing had non-significant effect on all reproduction traits. The estimates for AFS, AFL and FLI in first period are lower than later periods which might be due to the reason that the selected ewes were purchased from field in 2001 and their lambs were heavier. The present finding were in close agreement with those reported by Qureshi et al. (2010) in Kajli sheep, Gowane et al. (2014) in Malpura sheep, Lakew et al. (2014) in  Dorper×Local crossbred, and Reddy (2015) in Nellore brown sheep. However, Dey and Poonia (2005) in Nali sheep, Baber and Javed (2009) in Lohi sheep and Das et al. (2014) in Kashmir Merino sheep found non-significant effect of period of birth on age at first service.

Table 2: Least squares means along with standard error for reproduction traits in Munjal sheep

Effects No. of Observation Traits
AFS(days) WFS(kg) AFL(days) WFL(kg) FLI(days)
Overall  (µ) 287 563.08 ± 14.43 29.06 ± 0.16 713.48 ± 14.02 31.30 ± 0.16 351.82 ± 1.12
Period of Birth
2001-2002 57 385.52a ± 19.87 33.04f ± 0.54 531.97a ± 20.15 35.21g ± 0.54 262.84a ± 5.07
2003-2004 60 489.97b ± 18.59 30.95e ± 0.47 636.76b ± 18.73 33.20f ± 0.47 362.70c ± 4.39
2005-2006 37 536.01c ± 22.37 29.40c ± 0.66 692.74c ± 22.90 31.53d ± 0.66 378.55e ± 6.29
2007-2008 31 570.07d ± 25.42 30.42d ± 0.79 724.00d ± 26.22 32.70e ± 0.80 367.99d ± 7.66
2009-2010 36 610.34e ± 20.58 28.58b ± 0.57 760.65e ± 20.93 30.68c ± 0.57 362.33c ± 5.42
2011-2012 23 643.34g ± 19.85 25.60a ± 0.53 792.56g ± 20.12 27.72a ± 0.54 365.33cd ± 5.06
2013-2014 19 628.80f ± 22.00 28.73b ± 0.64 778.05f ± 22.49 30.80c ± 0.64 363.09c ± 6.11
2015-2016 24 640.60g ± 31.24 25.81a ± 1.04 791.64g ± 32.51 28.47b ± 1.05 351.75b ± 10.09
Dam’s Age at Lambing
<36 month 101 555.94 ± 14.99 29.02 ± 0.22 704.63 ± 14.68 31.34 ± 0.22 348.50 ± 1.85
36-48 month 69 565.17 ± 15.86 29.32 ± 0.30 715.14 ± 15.65 31.58 ± 0.30 353.10 ± 2.63
48-60 month 58 561.97 ± 15.64 28.72 ± 0.28 712.34 ± 15.42 30.89 ± 0.28 352.42 ± 2.46
60-72 month 42 562.78 ± 18.23 29.23 ± 0.45 712.15 ± 18.34 31.49 ± 0.45 349.69 ± 4.19
>72 month 17 564.94 ± 17.52 28.96 ± 0.40 714.28 ± 17.53 31.17 ± 0.40 351.30 ± 3.77

Means with different superscript for an effect differed significantly (P<0.05)

Least Squares Means

The overall least squares means AFS, WFS, AFL, WFL and FLI were estimated  as 563.08±14.43days, 29.06±0.16 kg, 713.48±14.02 days, 31.30±0.16  kg and 351.82±1.12 days, respectively. The present findings are in close agreement with those reported by Dixit et al. (2002) in Bharat merino and Jahan et al. (2013) in Balochi sheep. The estimates obtained in the present study were on higher side than those reported by Dey and Poonia (2005) in Nali, Jahan et al. (2013) in Balochi, Poonia (2008) in Munjal, Panda et al. (2012) in Edka, Mane et al. (2014) in Decani and Lakew et al. (2014) in Dorper×Local crossbred sheep. The estimates obtained in the present study were on lower side than those reported by Baber and Javed (2009) in Lohi, Qureshi et al. (2010) in Kajli, Gowane et al. (2014) in Malpura and Kumar et al. (2016) in Harnali sheep. Poonia (2008) reported that the ewes lambing for the first time had longer lambing interval (287.39±10.14), which decreased in the subsequent lambings.

Genetic Parameters

Heritability estimates for AFS, WFS, AFL, WFL and FLI were estimated as 0.19±0.12, 0.24±0.15, 0.17±0.10, 0.27±0.15 and 0.05±0.01, respectively (Table 3). The heritability estimate for AFS in the present study was in close agreement with those reported by Dey and Poonia (2005) in Nali and Reddy (2015) in Nellore brown sheep and lower than those reported by Baber et al. (2008) in Lohi and Akhtar et al. (2008) in Hissardale sheep.

Table 3: Heritability (diagonal), genetic (above diagonal) and phenotypic (below diagonal) correlations along with standard error among reproduction traits

Traits AFS WFS AFL WFL FLI
AFS 0.19 ± 0.12 -0.04 ± 0.03 0.96 ± 0.01 -0.12 ±0.10 -0.17 ± 0.15
WFS 0.09 ± 0.05 0.24 ± 0.15 -0.05 ± 0.10 0.94 ± 0.03 0.05 ± 0.02
AFL 0.97**± 0.01 0.12*± 0.05 0.17 ± 0.10 -0.12 ±0.08 -0.14 ±0.06
WFL 0.06 ± 0.05 0.94**± 0.01 0.07 ± 0.05 0.27 ± 0.15 0.14 ± 0.11
FLI 0.01 ± 0.05 -0.12*± 0.05 0.01 ± 0.05 -0.11 ± 0.05 0.05 ± 0.01

** Significant at P<0.01, * Significant at P<0.05

The heritability estimate for WFS in the present study was higher than those reported by Akhtar et al. (2008) in Hissardale and lower than those reported by Dey and Poonia (2005) in Nali, Baber (2008) in Lohi and Gowane et al. (2014) in Malpura sheep. The heritability estimate for AFL was in close agreement with those reported by Dixit et al. (2002) in Bharat Merino, Dey and Poonia (2005) in Nali and Gowane et al. (2014) in Malpura sheep and lower than those reported by Akhtar et al. (2008) in Hissardale and Kumar et al. (2016) in Harnali sheep. The heritability estimates for WFL in the present study were in close agreement with those reported by Gowane et al. (2014) in Malpura sheep, Khan et al. (2017) and higher than those reported by Akhtar et al. (2008) in Hissardale sheep and lower than those reported by Singh and Manuja (2000) in Gaddi and Dey and Poonia (2005) in Nali sheep. Low estimates of heritability for reproduction traits indicated that these traits are mostly influenced by environmental factors and can be improved by better managemental practices.

The genetic correlations of AFS with AFL (0.96±0.01) and WFS with WFL (0.94±0.03) were high and positive. The genetic correlation of AFS and AFL were found low and negative with WFS, WFL and FLI. Dey (2004) also reported high and positive genetic correlations of AFS with AFL. The phenotypic correlations of AFS with AFL (0.97±0.01) and WFS with WFL (0.94±0.01) were high, positive and significant. The phenotypic correlation of AFS and AFL were found low, positive and non significant with other reproduction traits. Dey (2004) reported moderate to high, positive and significant phenotypic correlations of AFS with AFL, WFS and WFL. The magnitude of association was more between AFS and AFL. The genetic correlations between traits pointed forward the conclusion that the early maturing ewes should be selected to have lower age at first lambing and more weight at lambing.

Conclusion

Development of breeding objectives and effective genetic improvement programme require knowledge of the genetic variation among reproduction traits and accurate estimates of heritability and genetic correlations of reproduction traits. Low estimates of heritability for reproduction traits indicated that these traits have low additive genetic variance and mostly influenced by environment. So, these traits can be improved by better managemental practices. Thus, identifying the source of variation and minimizing their effect is necessary for better reproductive health of Munjal sheep.

Acknowledgement

The authors are indebted to the Vice Chancellor, Lala Lajpat Rai University of Veterinary and Animal Sciences, Hisar, Haryana for providing the infrastructure facilities that enabled the successful completion of the project.

References

  1. Akhtar P, Ali S, Hussain A, Mirza MA, Mustafa MI and Sultan AI. 2008. Heritability estimates of post-weaning performance traits in Hissardale sheep in Pakistan. Turkish Journal of Veterinary Science. 32(4): 275-279.
  2. Babar ME, Abdullah M, Javed K, Ali A. and Ahmad N. 2008. Phenotypic and genetic correlations between age and weight at first service in Lohi sheep. Journal of Animal and Plant Science. 18: 11-13.
  3. Baber ME and Javed K. 2009. Non-genetic factors affecting reproductive traits in Lohi sheep. Acta agricultute scandinavica, section a- animal science. 59: 48-52.
  4. Chandar, S. (2012). Genetic evaluation of growth, wool and reproduction traits of magra sheep. M.V.S.c. Thesis. . Rajasthan University of Veterinary and Animal Sciences, Bikaner, India.
  5. Das AK, Chakraborty D, Kumar N, Gupta P, Khan NN and Bukhari S. 2014. Effect of non-genetic factors on performance traits of Kashmir Merino sheep. Indian Journal of Animal Research. 48(2): 106-108.
  6. Dey B. 2004. Genetic studies on reproduction and production traits of Nali sheep. M.V.Sc. Thesis, CCS Haryana Agricultural University, Hisar, Haryana, India.
  7. Dey B and Poonia JS. 2005. Reproductive performance of Nali sheep. The Indian Journal of Small Ruminant. 11: 10-13.
  8. Dixit SP, Dhillon JS and Singh G. 2002. Sources of variation in reproductive traits of Bharat Merino sheep. Indian Journal of Animal 72(4): 328-331.
  9. Gowane GR, Chopra A, Prakash V and Arora AL. 2010. Estimates of (co) variance components and genetic parameters for body weights and first greasy fleece weight in Malpura sheep. Livestock Science. 131: 94–101.
  10. Gowane, G.R., Prince, L.L.L., Paswan C., Mishra, S.S., Sharma, R.C. and Naqvi, S.M.K. 2014. Genetic analysis of reproductive and fitness traits of Malpura sheep in semi-arid tropics of India. Agriculture Research. 3(1): 1-8.
  11. Harvey WR. 1990. Mixed model least squares and maximum likelihood computer program, January.
  12. Jahan M, Tariq MM, Kakar MA and Waheed A. 2013. Reproductive Performance of Balochi Sheep in Different Ecological Zones of Balochistan, Pakistan. Pakistan Veterinary Journal. 33(1): 37-40.
  13. Khan NN, Assad N , Kumar N , Chakraborty D , Ayaz A , Dar MA , Ali A and Yousuf S. 2017 Wani1Genetic Parameters of Reproduction Traits in Rambouillet Sheep. International Journal of Current Microbiology and Applied Sciences. 6 (8): 2090-2094
  14. Kumar S, Dahiya SP, Malik ZS, Patil CS and Magotra A. 2016. Genetic analysis of performance traits in Harnali sheep. Indian Journal of Animal Research. DOI: 18805/ijar.v0iOF.7827.
  15. Kramer CY. 1957. Extension of Multiple range tests to group correlated adjusted means. Biometrics. 13: 13-18.
  16. Lakew M, Haile-Melekot M, Mekuriaw G, Abreha S and Setotaw H. 2014. Reproductive performance and mortality rate in local and Dorperx Local crossbred sheep following controlled breeding in Ethiopia. Open Journal of Animal Science. 4: 278-284.
  17. Lalit, Malik ZS, Dalal DS, Patil CS, Dahiya SP and Dev K. 2016. Reproductive performance of Harnali sheep. The Indian Journal of Small Ruminant. 22(2): 234-236.
  18. Mane PM, Pachpute ST and Nimase RG. 2014. Growth and reproductive performance of Deccani sheep in an organized farm. The Indian Journal of Small Ruminants. 20(2): 23-27.
  19. Panda P, Rao PK and Kumar P. 2012. Performance of edka sheep of Puri district of Odisha. The Indian Journal of Small Ruminants. 18(2): 188-190.
  20. Poonia,J.S. (2008). Reproductive performance of Munjal sheep. Indian Journal of Small Ruminants. 14: 121-132.
  21. Qureshi MA, Babar ME and Ali A. 2010. Performance of Kajli sheep in Pakistan: reproduction as influenced by environment. Pakistan Journal of Zoology. 42(4): 413–417.
  22. Reddy VV. A study of productive and reproductive performance of Nellore brown sheep. M.V.S.c Thesis. SRI Venkateswara veterinary university, Hyderabad, India.
  23. Robertson A. 1959. The sampling variation of genetic correlation coefficient. 15: 469-485.
  24. Singh U and Manuja NK. 2000. Genetic and phenotypic correlations of reproductive and productive traits in exotic and their crosses with Gaddi sheep in Himachal Pardesh. Indian Journal of Animal Science. 70(1): 63-64.
  25. Snedecor GW and Cocharan WG. 1968. Statistical methods, Oxford & IBH Publ. Co., New Delhi, India.
  26. Swiger LA, Harvey WR, Everson DO and Gregory KE. 1964. The variance of interclass correlation involving groups with one observation. Biometrics. 20: 818-826.
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