Actual genetic parameters for feed conversion rate of station tested progenies of Pietrain boars in Lower Saxony (brief report).

摘要

In swine, economic relevance of feed conversion rate is increasing in view of noticeable increased feeds costs. So, genetic parameters for feed conversion rate together with five other traits out of the complexes fattening performance, carcass and meat quality were estimated. Using the same models and the estimated variance components a breeding value estimation for all six traits was conducted for calculation of breeding value differences between selected (10%) and non selected boars in all cases of trait specific selection to compare direct and indirect selection responses for feed conversion rate. Data originated from 2577 female pigs station tested under ad libitum feeding with a standardised feed. These crossbred progenies of Lower Saxony Pietrain boars were kept in groups of ten pigs with electronic feeding stations. Estimated heritabilities for the fattening performance traits daily gain, feed intake and feed conversion rate are on a consistent level (h2 = 0.47 to 0.53). Feed conversion rate shows clear genetic relationships to their input variables feed intake (r_g=0.31) and daily gain (r_g = -0.51). These input variables are correlated with r_g= 0.66. An undesirable direction of estimated genetic correlations exists between the two fattening performance traits (daily gain and feed intake) and the two carcass traits backfat thickness (r_g = 0.20 and r_g = 0.52) and lean meat content (r_g = -0.20 and r_g = -0.59). Growth rate and feed intake have small genetic correlations to pH₁ loin (r_g = 0.11 and r_g = -0.00). A direct selection of the boars according to feed conversion rate breeding values leads genetically to increased growth rates and better carcass, reduced feed consumption and almost constant meat quality. However, in progenies growth rates will be far from growth potential and feed intake will decrease. At longer term this reduction of feed consumption will limit further increase of growth rates. The results are valid only for ad libitum feeding regime as realised in the test station. Further establishment of restricted feeding in practice as reaction on strong changes of the economic conditions could induce an adjustment of the test station feeding regime. In this case, advantages (e.g. better feed conversion rate and less fat deposition) and disadvantages (e.g. less growth rates and decreased breeding value variability, limited transferability to ad libitum conditions) should be contrasted.