Research Results - (PDF, 101 mb) - USAID

example, the EAG does may have been on
average further into lactation than the other
breed-types. The data evidences a considerable
improvement in milk yield with infusion of
genes from the dairy Toggenburg and Anglo
Nubian breeds. The yield of the KDPG is
consistent with a 3.5 kg peak daily yield and
sufficient variation is evident in the breed-type
to allow selection to ensure the breeding goal
and also to reduce the variation in yield that is
evident in the existing first generation KDPG.
Future work will gather daily yields for
completed lactations on sufficient numbers of
animals to allow quantification of sources of
variation in milk yield including breed-type and
to determine genetic parameters for evaluation
of the sires of lactating does to facilitate selection.
View A&M University and from the University
of Nairobi.
C. Selection Response
Table 3. Distribution of Genotypes at Ol'Magogo Research Station
October 1989
EAG/Galla F1 KDPG
Does 440 282 118
Bucks 32 201 114
Total 472 483 232
B.Multiplication
From October 1989 to June 1990, animal
numbers at Ol'Magogo increased as shown in
table 3
Numbers of purebred indigenous goats
are decreasing proportionally to Fls and KDPGs
as the breeding program emphasis moves
towards producing the four-way synthetic from
Fls and inter se mating of KDPGs. An effort to
utilize the purebred EAG/Galla as recipients in
an Multiple Ovulation and Embryo Transfer
(MOET) program was unsuccessful because of
lack of supplementary funds to achieve this
program. Vigorous efforts will be expended in
an attempt to implement this program in February-March,
1991. In addition, efforts will be
made simultaneously to run an ET training
school in Kenya and produce greater numbers
of KDPG from purebred EAG/Galla with the
collaboration of reproductive physiologists from
the International Dairy Goat Center at Prairie
A computer model that simulates small
ruminant performance was used to project how
sheep in northern Kenya would respond to
selection for mature size and milk production.
Three selection intensities were employed which
corresponded to culling ewes at five, six, or
eight years of age. In addition, rams were
replaced every one or two years. With the
simulation model it was possible to evaluate
flock productivity as well as individual animal
performance over 15 years. Flock performance,
determined by protein efficiency, indicated that
in this arid environment, culling ewes at eight
years of age was the most beneficial practice in
June 1990
EAG/Galla F1 KDPG
322 329 155
38 233 135
360 562 290
terms of increasing protein efficiency. Culling at
five years of age decreased protein efficiency for
much of the 15-year pg horizon and resulted in
decreasing total flock size. These results suggest
that selection could be practiced on this population
but that the high rates of replacement
usually recommended for optimizing genetic
progress resulted in non-optimal levels of flock
productivity due to decreased levels of flock
maturity. Consequently, high level of selection
intensity should be used to compensate for
modest ewe replacement rates to maximize the
merit of replacements.
Intensity of selection and culling strategies
impact the rate of genetic progress obtained
in selection programs. Several studies have
addressed the issue of optimizing genetic
progress by balancing culling rates and selection
intensity. However, a question not completely
addressed by these studies is how production
changes over time as populations are undergoing
selection. A major factor influencing the
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