Proceedings of the New Zealand Society of Animal Production.
1979, 39: 118-128
Proceedings of the New Zealand Society of Animal Production.
1979, 39: 118-128
Body composition studies on mice sampled from all four lines were made a generation 5 (at an average age of 16 weeks) and generations 12 and 20 (6 weeks of age). At 6 weeks of age, the line selected for 3-week weight was fatter and the line selected for 6-week weight leaner than the control line. To investigate this finding more definitely, serial slaughter was carried out at generations 23, 29 and 37. These data were then pooled and analysed on a within-sex basis. There were only small differences among lines in the pattern of fat deposition in male mice. But in females, which were fatter than males, there were differences among lines in fat deposition. The line selected for 3-week weight was the leanest line at its selection age but became progressively fatter at older ages and significantly fatter than mice from the 6-week weight or control line. In contrast, the line selected for 6-week weight was the leanest line at 6 weeks of age and at older ages. The line selected for 3-6 week gain had a similar pattern of fat deposition to the line selected for 3-week weight from about 6 weeks of age and older.
These results are discussed in relation to models in the literature which postulate the genetic relationships among age at selection and growth rate, feed efficiency, appetite and body composition.
Keywords: NZSAPAB;
