The investigations reported are based on two studies; the first
is concerned with the selection practiced for performance in one inbred
Angus and three inbred Hereford lines of cattle, the realized
responses, levels of inbreeding and associated performance, and
heritabilities of the performance traits.
Selection differentials for all performance traits...
Eight purebred rams (four Suffolk and four Panama) previously
selected as high and low on the basis of post-weaning performance
feed test of 84 days were used each of three years. Each of the
rams was mated to approximately 25 grade Panama ewes each year.
One ram and 25 ewes...
An experiment was conducted to examine the responses to
selection for high and low rate of gain in the mouse under a system
whereby inbreeding was maximized. Rate of gain was measured by an
index designed to include gains in both the pre- and postweaning
periods with the gains in...
There were two studies involved in the thesis research. In the
first study, variation in the amount of adenohypophysis gonadotropins
among 22 individual beef bulls were investigated. These bulls
represented four inbred lines, and six linecrosses. The bulls were
raised in the Oregon State University purebred herd.
The bulls were...
The first study utilized ova transfer in sheep and involved
hormonal treatments for synchronization of estrus and superovulation
in an investigation of crossbred maternal influences on inbred and
linecross lambs.
Synchronization of estrus in ewes was achieved effectively
with either oral progestogen, 6 α-methyl-17α-hydroxy-progesterone
acetate (60 mg./ewe/day), or intramuscular injections...
One of the most important productive characteristics of hogs is reproductive efficiency. Reproductive efficiency is best measured by litter size at weaning. Litter size at birth and weight of the pigs at birth are among the most important factors affecting litter size at weaning. It has been demonstrated that less...