A Preliminary Assessment of the Reproductive Performance of Nilotic Bucks under Intensive Management in the Semi-arid Climate of Khartoum

Abstract

Three Nilotic bucks were fed sorghum-based diet and three
molasses-based diets to examine the effect of nutrition and seasons in
Khartoum (Sudan) on the scrotal circumference, sexual behaviour and
semen quality. Reaction time was recorded in seconds from introduction
to a goat in oestrus until ejaculation into an Artificial Vagina (AV). The
scrotal circumference was measured around the width of the two testicles
once every month. Semen was collected by an AV at weekly intervals.
Semen characteristics examined were volume of the ejaculate,
spermatozoa motility and concentration. Although the Nilotic bucks did
not have a period of sexual quiescence, they had an active mating season
starting at the beginning of autumn as indicated by the improved semen
quality and reaction time (22.8 and 17.0 sec in autumn and winter as
compared to 72.3 sec in summer). Testicular circumference reached its
maximal size at the beginning of autumn (20.17 cm), remained at this
level until mid-winter, and then declined thereafter and reached its
minimal value during the next summer (17.08 cm). The season affected
all semen characteristics examined and the best semen was obtained in
autumn and winter. However, the magnitudes of these seasonal effects
may not be sufficient to prevent the bucks from being used for breeding