THE EFFECT OF INSEMINATION TIMING ON FERTILIZATION AND EMBRYO GENDER IN ZARAIBI GOATS

SUMMARY
The purpose of this study was to evaluate the effect of pH of cervical mucus
and vaginal temperatures from onset of oestrus up to insemination time on sex ratio in
Zaraibi goats. Three Zaraibi bucks were used for semen collection. Semen was
evaluated and immediately diluted with tris-yolk fructose (TYF) extender. Nanny goats
(n=44) were artificially inseminated with 1 ml extended semen containing 600x106
motile spermatozoa. Nanny goats were allocated into four groups (11 females each).
The interval time to estimate pH of cervical mucus and vaginal temperatures during
oestrus period was 6 hrs. Artificial insemination was performed as following: group
(G1) goats were artificially inseminated at onset of oestrus (zero time) which
considered as control group. The groups G2, G3 and G4 were artificially inseminated at
12, 24 and 36 hours (hrs) after beginning of heat , respectively. Oestrus was detected
eight times daily with three hours interval and determined when doe stand to be
mounted. The results indicated that the lowest (P<0.05) value of pH of cervical mucus
and vaginal temperatures were recorded at 24 and 30 hours of heat. The kidding rates
were 54.5, 81.8, 100 and 100 in groups 1, 2, 3 and 4, respectively. Goats inseminated at
0 hr (G1) gave 50% males and 50% females. Goats inseminated at 12 hr produced
62.50% males and 37.50% females. The highest female ratio of offspring (84.62% vs.
15.38% male) were obtained in G3. In contrast, G4 recorded 73.08% male and 26.92%
female kids. 
It is proved that the period between onset of oestrus to insemination time is
able to alter forward motility for either X or Y chromosomes to change the sex kind of
fetal gender in Zaraibi nanny goats.