Studies were conducted to assess influencing the effectiveness of sheep for grazing control of false brome (Brachypodium sylvaticum) an invasive grass species. Orphan lambs were exposed to false brome via grass extract in their milk and naturally reared lambs were exposed by grazing dense stands of false brome with their...
This dissertation develops mixed family selection for Pacific oysters using marker-based pedigree reconstruction. It focuses on improving the efficiency of parentage assignment, determining the optimum life stage to mix oyster families for rearing and selection, comparing mixed-family and separate-family selective breeding in the field, and applying the mixed method to...
Embryonic loss of potential lambs resulting in partial failure of multiple ovulations is a significant factor in the reproductive rate of prolific breeds. The roles of genetic and nutritional variation (and their possible interaction) on embryonic loss were studied by mating blackface and whiteface ewes of either high or low...
Use of sheep to control weeds in a ryegrass-white clover pasture in which Knob Cone-Monterrey hybrid pine trees had been planted was investigated in Corvallis, Oregon during 1997-1998. Treatments consisted of an ungrazed control (C) and grazing applications to achieve 25 (L), 50 (M) or 75 (H) percent utilization of...
Callipyge (CLPG, n=16) and normal (N, n=11) lambs were
produced from Polypay dams and Dorset sires heterozygous for
the CLPG gene to study the effects of the gene on growth and
carcass and meat quality parameters. CLPG lambs had higher
average daily gain than N lambs (0.26 vs 0.23 kg/day,...
A series of trials was conducted with Polypay (P), Coopworth
(CP), Hampshire (H), and crossbred ewes over a two year period at three
locations to assess the effects of ewe body condition and pre-lambing
supplementation on ewe productivity. Supplementation trials were
conducted at all three locations in Year 1 using...
Coopworth sheep, a newly available genotype, were compared with
other genotypes in two trials to assess cumulative lamb and wool
production and contributing components related to survival, reproduction
and growth, and for the effects of ewe body weight on reproductive traits.
In a third trial, various genotypes generated in the...
Two trials were conducted over consecutive years to examine the effects of ewe
body condition and post-mating nutrition on ovulation rates and embryo survival. Trial 1
used 146 Polypay ewes ranging in age from 5 to 8 years in a 3 x 2 factorial array of pre-mating
(high-H, low flushed-LF...
Grazing experiments were conducted in summer, autumn and winter
to assess the effects of stock density, grazing duration, pre-grazing
pasture mass and stock type on forage intake by sheep grazing at high
stock densities for short durations. In summer and winter, sheep were
stocked at 200 sheep/ha on 0.1 ha...
Two concurrent trials were conducted to examine genetic and
environmental influences on growth rate, carcass fatness
and muscle fiber type proportions. Trial 1 compared
Polypay and Coopworth x Polypay male lambs either left
intact or castrated early, mid or late in growth. Trial
two compared Hampshire sired lambs (females, early...