Genetics of growth and reproduction in the turkey. 13. Effects of repeated backcrossing of an egg line to two sire lines.
The objective of the present study was to determine the feasibility of rapidly increasing the BW of dam lines by repeated backcrossing of a dam line to a sire line. A line (E) selected long-term for increased egg production was backcrossed to a line (F) selected long-term for increased 16-wk BW (BC1) and to a commercial sire line (BC2). The BW of the F and commercial sire lines were about twice as large as that of the E line. Egg production of the E line was more than double the egg production of either of the sire lines. Large gains in BW and breast width were observed in both backcrosses. Based on additive genetic variation, gains in BW were less than expected in the first generation for females in the BC1 and for both sexes in the BC2. Values observed for males of the BC1 were similar to expected values at 8 and 16 wk and larger than expected values at 20 wk of age. Slower than expected BW gains in Generation 1 may have been attributable to the small egg size of E females. After Generation 1, BW at 16 and 20 wk of age were equal to, or greater than, expected. Egg production was reduced in both backcrosses relative to the E line. Fertility and hatchability were reduced relative to the E line by backcrossing in BC1 but not in BC2. Results of the present study suggest limited repeated backcrossing of a dam line to a sire line may be an economically feasible method to greatly increase the BW of dam lines without unduly sacrificing reproduction capability.
Nestor
K E
KE
Department of Animal Sciences, Ohio Agricultural Research and Development Center, Ohio State University, Wooster 44691, USA.
Noble
D O
DO
Emmerson
D A
DA
D000375:Aging; D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D003433:Crosses, Genetic; D004531:Eggs; D005260:Female; D005298:Fertility; D008297:Male; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000254:growth & development*; D010058:Oviposition; D011995:Recombination, Genetic; D012727:Sex Characteristics; D014422:Turkeys / Q000235:genetics* / Q000254:growth & development