Abstract:
The objective of this work was to evaluate the
effect of two synchronization methods with prostaglandins
F2α (PGF2α) on heifers and multiparous cows. Fourty-three
Bos indicus cows (white and Red Fulani) were divided into
four groups in a two-by-two factorial structure, parity x method
of synchronization. The synchronization methods
consisted of a two-dose regime which involved injection of
animals on day 0 with PGF2α (Lutalyse) at 5 ml per cow
intramuscularly. On day 11, the injection was repeated at the
same dosage. On day 14 (72 h after the second injection), a
fixed-time artificial insemination (AI) was done. On day 15
(96 h after the second injection), a second insemination was
done. The one-and-a-half-dose regime consisted of an injection
similar to the first treatment mentioned above on day 0.
Thereafter, cows were observed for heat, and anyone showing
heat was inseminated. A second dose was given on day 11 to
all animals not having shown any heat. A fixed-time AI was
done on days 14 and 15. Blood samples were collected on the
day 0 of insemination for each cow while day 11 and day 21
after insemination. Progesterone was analysed by means of standard ELISA progesterone kits to determine its profiles
after insemination. Results show no evidence of the effect of
treatments on conception rates (P>0.05). Similarly, heifers
and multiparous cows had similar conception rates
(P>0.05). Between 3 weeks and 3 months of pregnancy, there
was a loss of embryos of 28 % in heifers and 20 % in
multiparous cows, but the difference between the two groups
was not significant (P>0.05). It recommended that farmers do
not synchronize animals with poor body condition score
(BCS). They should also monitor weight gains of heifers,
remove them from the herd when they have been mixed with
young growing bulls and put them in a breeding herd. The
two-dose regime is better to be used in areas where the
inseminator cannot easily be available.
