THE POTENTIALITY OF MILK PRODUCTION AND LACTATION CURVE IN DHOFARI GOAT

SUMMARY
Records of 233 Dhofari does, progenies of 40 sires, were available for this study. The present study was carried out in the Livestock Research Station at Salalah, Sultanate of Oman. During the inception phase, this flock has been composed of four suggested ecotypes; Elwasat, Elsharkiya, Elgharbiya and Najd. The objective of this study was evaluating the potentiality of these suggested ecotypes and hence the potentiality of Dhofari goat towards milk production, assessing the effect of ecotypes and lactation years on some milk production traits as well as characterize the lactation curve and its parameters together with those factors affecting it. Milk production data were recorded from does in their first lactation season in two successive years. The present study dealt with total milk yield (TMY), the 90 days cumulative milk yield (M90), lactation period (LP), persistency (PR), the lactation curve peak of production and lactation curve parameters (a, b and c) according to the Wood nonlinear model. The present study estimated least square means of TMY and M90 as 51.08 kg and 26.56 kg, respectively. Results indicated highly significant impact of lactation year on TMY, M90 and PR. Among all lactation curve parameters, ecotype and lactation year have only significant effects on “a”. The first year of lactation was always higher than the second one for these traits. Furthermore, the shape of lactation curves for Dhofari goat was described to have initial milk production of 0.217 kg, a rate of ascending phase of 0.83 kg/week and a decline rate of -0.14 kg/week during the descending phase. LP was about 32 weeks (226.10 days), the actual peak milk yield of 0.37 kg has been initiated at about 4.3 weeks and terminated at a peak milk yield of 0.41 kg in 11.6 weeks, and then the curve tended to decrease gradually until the end of lactation with an average persistency of 64.17%. Heritabilities of TMY, M90 and PR were estimated as 0.08, 0.05 and 0.46, respectively. Genetic and phenotypic correlations between M90 and TMY were 0.60 and 0.86, respectively.The present study provides evidence that Dhofari goat possess a promising potential for milk production that could response to genetic improvement process and recommends pooling the studied four ecotypes together as a Dhofari goat breed.