GENETIC-PARAMETERS FOR LAMB WEIGHT AT DIFFERENT AGES AND WOOL PRODUCTION IN BALUCHI SHEEP

The Baluchi breed is the most common native breed of Iran adapted to h arsh environments in the eastern parts of the country. The data used i n the present study, collected from two research flocks at the Abbasab ad sheep breeding station in north-east Iran, included 20 534 animals descended from 363 sires, 5992 darns, 282 maternal grandsires, and 286 5 maternal granddams during the period 1966 to 1989. The traits record ed were: birth weight (BW), weaning weight (WW), weight at 6 months (W 6), weight at 12 months (YW), pre-weaning gain (WG), post-weaning gain (PWG), lamb fleece weight (LFW), ewe fleece weight sheared before fir st joining (FW1) and adult ewe fleece weight (FW). Genetic parameters, estimated with restricted maximum likelihood and a two-trait animal m odel, were similar in the two flocks. Direct heritabilities for the va rious body weight traits were moderate and varied between 0.13 and 0.3 2, while the maternal heritabilities were low and varied between 0.01 and 0.12. Direct and maternal genetic correlations between WW and weig hts at later ages were moderate to high (0.59 to 0.96). Direct heritab ilities of weight gain measures varied between 0.12 and 0.19, while no significant maternal influence on either of these weight gain measure s could be detected. The estimates of direct genetic correlation betwe en WG and PWG were positive and varied between 0.54 and 0.74, while ne gative maternal genetic correlation (-0.17 on average) between WG and PWG was detected. For LFW, direct heritability was low and no maternal heritability could be shown. For FW1, both direct and maternal geneti c influences were demonstrated (0.07 to 0.26). Direct genetic correlat ion between LFW and FW1 was very low and close to zero, while maternal genetic correlation was positive and relatively high (0.72 on average ). The relative contributions to phenotypic variance from variance com ponents due to common environmental effects ranged from 0.01 to 0.15 f or all traits. The repeatability of FW was low (0.03 to 0.12).