The understanding of the development and growth of an ovulatory follicle
within the ovary is important in order to improve the efficiency of breeding
techniques such as artificial insemination (Al) and embryo transfer. The
objectives of the study were to determine the effects of different levels of
energy diets on characteristics of oestrous behaviour by visual observation,
and follicular development in cows. The experiments were conducted to
determine the oestrous behaviour by visual observation and the effects of
dietary energy levels on follicular development in crossbred cows offered
different levels and duration of energy diets. Thirty crossbred Kedah-Kelantan
(KK) cows were divided into two groups, I) n=15; received grass with
maintenance supplement and II) n=15; received grass with double
maintenance supplement. Oestrous was initially synchronised using
chloprostenol intra vaginal progesterone releasing device (CIDR-B@)
containing 1.38 g progesterone for 7 days and administered 1 ml synthetic
prostaglandin analogue 2 days before CIDR-B@ removal. The cows were
observed for estrous behaviour continuously 24 hours daily for 72 hours
immediately after CIDR-B@ removal. The ovaries then were visualized using
7.5 MHz linear array transrectal transducer attached to a real-time, B mode
portable ultrasound. Scanning was carried out from six hours at the beginning
of estrous and repeated every six hours until ovulation. The day of first
detection of a 2 4 rnm follicle identified as a dominant follicle was taken as
the first day of a follicular wave. During each ultrasound examination, a single
blood sample was drawn and collected into 10 ml plain tubes for
determination of progesterone concentration. A timed insemination was
performed at 48 to 54 hrs after removal of CIDR-BB for all cows. Pregnancy
diagnosis was performed using ultrasonography and rectal palpation
techniques. In expressing oestrous behaviour characteristics, there were no
differences between group of single maintenance (GSM) and group of double
maintenance (GDM) (p>0.05) in the first cycle, while in the second cycle,
characteristics of oestrous behaviour were clearly seen. The results obtained
showed that approximately 33.3% of GSM and 40% GDM cows produced 2
waves of follicular development while 66.67% of GSM and 60% of GDM cows
produce 3 waves of follicular development. Both GSM and GDM had equal
number of cows producing 2 and 3 waves of follicular development. However,
the number of waves of folliwlar development, length of estrous cycle,
growth and regression rate of dominant follicle, and progesterone
concentration between GSM and GDM were not significantly different
(p>0.05). Therefore, the results from the experiment suggest that the higher
and longer period of energy levels would not accelerate the estrous
behaviour and increased the number of animals pregnant. From the study, it
was concluded that cows offered double maintenance levels of energy diet
was not significantly different from cows offered single maintenance levels of
energy diet in terms of exhibit oestrous behaviour, follicular development and
number of animal pregnant (P>0.05)
