SELCTION INDEX FOR SOME BODY MESUREMENTS TOWARDS IMPROVING MILK PRODUCTION IN DHOFARI GOAT

ABSTRACT
The present study investigate the possibilities of improving milk production in Dhofari goat raised
at Salalah of Sultanate of Oman through selection index containing body weight and dimensions at
birth. Records of 190 Dhofari does, daughters of 35 sires were available for this study. During two
successive years, data were collected on the same animal at birth (birth weight, BW; body length, BL;
body height at withers, BH; heart girth, HG and rear girth, RG) and after the first lactation season
(total milk yield, TMY). The present study estimated genetic and phenotypic parameters for the
studied traits and constructed 19 selection indices to predict TMY in Dhofari goat.
The present study estimated averages of BW, BL, BH, HG, RG and TMY as 2.9 kg, 31.4 cm, 34.7
cm, 33.6 cm, 37.0 cm and 50.0 kg, respectively. Among body dimensions, HG and RG were more
variable than BL and BH. Heritability estimates for all studied traits were little and ranged from 0.002
to 0.1. The correlation coefficients among all studied traits were genetically high and phenotypically
low. Genetic correlations between TMY and all live body measurements were close to one and much
higher than the corresponding phenotypic ones. Genetically and phenotypically, TMY had positive
correlations with BW, BL and BH and negative ones with HG and RG. The maximum accuracy of the
full index was 0.45. The greatest improvement in TMY was +0.25 kg. Selection on all indices reduced
HG and RG. Selection on I13 while reducing HG (-0.31 cm) and RG (-0.42 cm), it increases the size of
animal probably through BL (+0.11cm) and BH (+0.18 cm). The present study concluded that the
simplified selection index (I13) utilizing individual kid performance (HG and RG at birth) is the most
efficient (rTI =0.38), attain adequate improvement in TMY (+0.21 kg), less expensive and being about
13% more efficient in the improvement than direct selection for milk yield alone compared with the
other studied indices. Thus, I13 can be used as a selection criterion for the simultaneous improvement
of milk and meat production in Dhofari goat.