GENETIC PARAMETERS AND SIRE 'EVALUATION FOR GROWTH TRAITS IN EGYPTIAN RAHMANI· LAMBS. | ||
| Journal of Animal and Poultry Production | ||
| Article 12, Volume 27, Issue 2, February 2002, Pages 927-843 PDF (5.76 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jappmu.2002.253342 | ||
| Author | ||
| E. Z. M. Oudah, | ||
| Animal Production Department, Faculty of Agriculture, Mansoura University, PC 35516, Egypt. | ||
| Abstract | ||
| Data on 2417 Egyptian Rahmani lambs progeny of 114 sires collected over a 11-years period (1989 to 1999) were used in this study. The average number of lambs per sire was 19.01 . Lamb traits studied were weights at birth (BWT) , 3 (WT3) and 6 (WT6) months of age and averages daily weight gain (AOG) from birth to 3 (ADGO-3), from birth to 6 (ADGO-6) and from 3 to 6 (ADG3-6) months of age. Data were statistically analyzed utilizing the least squares mixed model and maximum likelihood (LSMLMW) computer program of Harvey (1990). The effects of sire as f2t'TCf€:lm effect, year and season of birth, sex of lamb (SL), type of lambil4g (TL) and SL X TL interaction as fixed effects on lamb traits. Birth weight of larnbwas. included in the model as linear and quadratic covariate. whan, at.lal~mSl all! stl:ldie:d'tl'ait'So except BM tfiait. Least squares means. (.±s:~ caIf~, 'iNJJrJ, S.w6JAOOQf.3l, AfIJ@£l,.Qand A[JG3r6. were 2.91 ± 0.033, 16 .. 6ii±«r.1;9m.24.4± (l) ~k9]" 15,1' ±2.1CJi,.119 ± 1'.63al'ld s.a ±: 2'.1.6 !!Jed. resp.ectiveIY. Sire (DE lal"1:lb" ~ea1T of birth and sex-of lal"}1.lo> I:latllni:gbl.y significant (P<0.001 J effects <MIl all: traits studied. Season of birth significantly (P<O.001) affected only WT3, AID.<G:0-31 amdi AIIJ'.G3\.$. Type of lambing had highly significant (P<O.001) effects on all traits' studied except ADG3-6. The effect of SL X TL interaction on all studied traits was not significant except WT3 and ADGO-3. The linear regression coefficients of all studied traits on BWT were positive and significant (P<0.05, 0.010r 0.001), meanwhile the quadratic regression coefficients were not significant except for AOGO·6 (P<0.05) and AOG3-6 (P<0.001) the coefficients were negative and significant. The proportions of sire variance components (82s) for all studied traits were 8.04 to 11.94%. Heritability estimates (±SE) for BWT, WT3, WT6 ADGO-3, AOGO-6 and AOG3-6 were 0.325±0.06, 0.363±O.07, 0.418±0.07, 0.383±0.07, 0.447±0.07, and 0.478±0.08, respectively. The genetic and phenotypic correlation coefficients among studied traits were high and positive (0.712 to 0.992) except between BWT and other traits were very weak or moderate and genetically negative with all averages daily gain (0.008 to -0.242) and between ADG3-6 and both AOGO-3 and WT3 were low and positive (0.122 to 0.188). Percentages of sires that had negative ETA estimates for studied growth traits were 47.6 to 54.0%. Estimates of estimating sire-transmitting ability (ETA's) as deviations from the overall means estimated using Best Linear Unbiased Predictors (BLUP) method for sires have 10 lambs at least ranged from -0.439 to 0.308, -1.684 to 2.735, -2.742 to 3.542 kg, -18.82 to 29.93, -13.76 to 19.65 and -15.46 to 31.57 g/d for BWT, WT3, WT6, ADGO-3, AOGO-6 and AOG3-6, respectively. Spearman rank correlation coefficients among values of sire transmitting abilities were generally high and positive (ranged from 0.311 to 1.00) except between BWT and each of BT3 and AOGO-3 were low (0.120 and 0.120, respectively) and between BWT and each of BT6, ADGO-6 and AOG3-6 were negative (ranged between -0.096 to -0.360). It is concluded that the traits can be improved by selection with no serious antagonisms among traits studied. | ||
| Keywords | ||
| sheep; growth rate; genetic parameters; sire evaluation; Egypt | ||
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