The genetic control of changes in unselected traits of
Wrolstad Medium White turkeys divergently selected for
semen ejaculate volumes (SEV) for 16 generations (G) was
studied. Genetic parameters were estimated in G 10 to 14
for embryonic mortality (EM), the incidence of pipped eggs,
and for total plasma cholesterol (PC) and high density
lipoprotein cholesterol (HDLC) in 16-week old birds of G
15. An attempt at determining enzyme polymorphisms in the
two lines was performed in G 16. A multivariate discriminant
analysis procedure was established in an attempt to
classify birds as low or high SEV based on fertility and
incubation records in G 10 and 12.
It was determined that a more reliable, yet flexible
method of estimation of variance components for
heritability of embryonic mortality in turkeys is a
likelihood procedure. The mean heritability estimates were
-.03 and .10 for embryonic mortality in the early (Days 1-
10) and late (Days 21-28), respectively. Estimates of
heritability for the incidence of pipped eggs were .21 and
.08 in the low and high lines respectively.
Since there were no line differences (P>.05) for PC
and HDLC, data was pooled from low and high SEV lines and
h² was computed to be -.03 and .26, respectively. Genetic
correlation among PC, HDLC, and 16 week body weight (BW)
varied from .05 between PC and HDLC, .13 PC and BW and -.34
HDLC and BW. No polymorphisms were observed for the enzymes
examined in the present study.
The discriminant function developed to categorize
birds as low or high volume semen producers, had a moderate
(.55) to high (.75) hit ratio for classification of birds
as low or high volume producers in G 10 and 12.
It was concluded that divergence in unselected traits,
embryonic mortality and the incidence of pipped eggs, in
the low and high SEV lines had a negligible additive
genetic control. Cholesterol, though a major intermediate
in the biosynthesis of steroid hormones, in turkeys at 16
weeks of age is not a suitable biochemical marker for SEV.
Although genetic control in turkeys appears to be
negligible for PC, there is a moderate and significant
hereditary influence on HDLC. With a misclassification rate
of .30-.40, fertility and incubation records, as
demonstrated here can be used to classify birds as low or
high volume semen producers. / Graduation date: 1992
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/36215 |
| Date | 05 December 1991 |
| Creators | Smith, Edward J. (Edward Jude), 1961- |
| Contributors | Savage, Thomas F. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
Page generated in 0.0018 seconds