| Summary: | Several studies were conducted to evaluate the use of
artificial insemination (AI) as a means to improve the reproductive
success of hand-reared wild-strain Mallards (Anas platyrhynchos).
The effects of age, mate choice and isolation on reproductive
parameters of captive Mallards were studied.
Eighteen adult and yearling hens were allowed physical,
visual-auditory or auditory only contact with drakes. In addition,
another 28 yearling hens were placed (17 random, 15 self-chosen)
with yearling drakes. Age of males was a key determinant in Mallard
reproductive success, specifically egg fertility. Self-chosen pairs
performed better than randomly assigned pairs and isolation of hens
from drakes did not affect egg production. The data suggests that
artificial breeding is needed to supplement natural mating and
increase egg fertility in yearlings.
Since egg fertility was generally low in captive held
yearling Mallards, comparisons between captive and free-flying
Mallard drakes were made to assess differences in gonadal
development. Measurements of numerous parameters indicated that,
gonadal development was suppressed in captive drakes of both age
classes. For the captive drakes, seasonal profiles of testosterone
(T) levels and semen characteristics were determined in yearlings
and adults. Plasma T concentrations increased from basal levels in
March, peaked in April and decreased to basal levels in May. The
decrease in T concentration to basal level occurred two weeks
earlier in yearlings compared to that of adults. Surprisingly,
semen volume and semen concentration were not different between the
two age groups. Mallards were artificially inseminated by modifying
a technique developed for domesticated poultry. Egg fertility
obtained with Al was 73%. Thus, these results suggest that Al may
indeed be used successfully in propagating wild Mallards.
Two poultry semen extenders [Beltsville Poultry Semen Extender
(BPSE) and Lake's Poultry Semen Extender (LAKE)] were compared with
respect to their effects ..on sperm survival and sperm fertilizing
capacity. BPSE and LAKE worked equally well to maintain the semen
fertilizing capacity during short-term storage. Last of all,
effects of various concentrations of cryoprotectants [glycerol,
ethylene glycol (EG), propylene glycol (PG) and sucrose] on the
fertilizing capacity of unstored chicken spermatozoa were tested.
The addition of sucrose to EG or PG on the viability of frozen-
thawed chicken semen was determined. Fertility declined with
increasing concentrations of glycerol and sucrose, but not with
increasing concentrations of EG and PG. The addition of sucrose
(0.2 M) did not improve freeze-thaw protection of EG and PG. === Land and Food Systems, Faculty of === Graduate
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