Browsing by Subject "päiväkasvu"

The aim of the fur production is a high-quality pelt. Selection on pelt size has lead to heavy and possibly obese animals. The obesity can impair animals' health, fertility, welfare and also damage the image of production. Fat animals are most likely increasing feed consumption and subsequent feed costs. A long and lean animal is an economical aim. Blue fox already has a subjective 5-level body score index (BSC), but the aim of this study was to develop a body mass index (BMI) which contains easily measured traits: length and weight. We also wanted to quantify the genetic variation of animals' length, daily gain and BMI and their relation to feed consumption. The data was from MTT's SOLAKKA experiment (2005-2006) where animals were raised in cages occupied by a pair of individuals. The feed consumption was analyzed at an individual- and cage-level. The BMI was developed using the data from the normal sized animals (BSC 3 and 4). The BMI parameters were calculated separately for males and females, because of their weight difference. Using the BMI we could determine with the length of normal sized animals' their required amount of feed. Further, we could calculate the joint feed requirement for a cage pair. The residual feed intake (RFI) was the difference between measured and predicted feed intake. The summed RFI was used for a cage pair. The genetic analyses were performed with R program MCMCglmm package which is based on Bayesian inference. Heritability of length varied 0.43-0.66, heritability of daily gain 0.72-0.83 and heritability of BMI 0.66-0.72. Heritability of dry matter intake was 0.71-0.85 and that of sum-RFI 0.43-0.48. The genetic correlation between sum-RFI and daily gain or BMI was high (0.60-0.63), hence selection on either trait would reduce also RFI. The selection on BMI would not affect length, while there was genetic correlation 0.42 between daily gain and length. The obesity problem of blue fox must be intervened and the BMI seems to be good tool for that. The consequences of its use must still be monitored.