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The genetic correlations among body weight (BW) at 28 days interval during the first year, and between reproductive traits and BW, were estimated using a multivariate animal model. The data consisted of BW at 168, 196, 224, 252, 280, 308, 336 and 364 days and egg size, egg number, egg volume and post-spawning weight of females. All the traits were measured individually but fish were identified at full-sib-family level at the first year while identified individually at spawning season. The estimated genetic correlations between eight BW were all significantly greater than zero and ranged from 0.24±0.09 for BW at 168 days to 0.93±0.02 for BW at 336 and 364 days. The estimated correlation between BW at contiguous ages were consistently high, ranging from 0.57±0.08 to 0.93±0.02, but decreased with increasing interval between ages. Also, there was a trend for the genetic correlations between BW at earlier ages to be smaller than those between BW at later ages, independent to age interval. The genetic correlations of reproductive traits with BW at ages prior to 252 days were not significantly different from zero, while those with BW at ages from 252 to 364 days were significantly greater than zero and increased with increasing age. The range of estimated genetic correlations between reproductive traits and BW at ages from 252 to 364 days were: for egg size, from 0.18±0.08 to 0.29±0.06; for egg number, from 0.21±0.08 to 0.32±0.06; for egg volume, from 0.28±0.08 to 0.45±0.06 and for post-spawning weight, 0.25±0.11 to 0.61±0.08. As a whole, the genetic correlations between reproductive traits and BW during the first year were favorable, allowing positive genetic improvement in both BW and reproductive traits. |
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