Research Results - (PDF, 101 mb) - USAID

the low or control lines. These results indicate
that selection for reproductive rate using an
index that measures reproductive rate in females
resulted in significant changes in testicular
parameters.
Much of the last half of the year was
devoted to phasing down the active research
projects and planning for the establishment of
an Andean Small Ruminant Network. The
breeding project has produced a book that is
currently in press that is a compilation of the
biology of the alpacas written by many of the
biological scientists involved with the SR-CRSP
in Peni
Research Results
Objectives
The objectives of the breeding component
of the of the Peru project this year was to
complete as many publications as possible and
to continue to analyze as much of our backlog of
data as possible.
Justification
Over the last ten years the animal breeding
component of the SR-CRSP in Peru had
collected large amounts of data that were ready
to be analyzed to evaluate the results of genetic
improvement projects. Therefore, in the final
year of the project in Peru work was focused on
analyzing and publishing much of the data
collected.
In the 1989-90 workplan, a long list of
publications was outlined; many of them were
completed (see publication list).
In summary, we found that heritabilities
estimated under the harsh high elevatTon
Andean environment are similar to those observed
elsewhere in the world. This indicates
that there is considerable genetic variation and a
sound selection program within breed should
result in considerable genetic progress. How-
98
ever, selection in general is being practiced on
phenotypic values that are not accurately assessed.
Thus little progress has been observed.
In criollo sheep we have crossed the
ewes with imported Targhee and Finn-cross
rams and with Junin and Corriedale rams. In
general, the crossbred lambs grew faster and
produced more kilograms of wool than did the
criollo lambs. The criollo ewes had higher
reproductive rates and higher lamb survival
than did the crossbred ewes. This is probably a
result of better adaptation to the environment of
the criollo ewes. Therefore, when expressed as
kilograms of lamb weaned per ewe exposed
there was little difference between the productivity
of the criollo ewes or the crossbred ewes,
with the criollo ewes having a small advantage.
Work at MSU has dealt with the evaluation
of physiological factors that have changed
as a result of selection for high and low reproductive
rate in Rambouillet sheep. This year's
work has evaluated testicular and hormonal
factors that have changed as a result of selection.
Cardenas (1990) found that there was no difference
in the area of the testis volume represented
by seminiferous tubules but rams selected for
low reproductive rate had a significantly (P