The Journal of Research ANGRAU

RAMANA et al
with small follicles measuring > 6 mm diameter. In
the ultrasound monitoring follicles measuring above
6 mm diameter and corpus luteum measuring 8-10
mm were detected by day 20-25 postpartum period.
The resumption of ovarian activity observed in this
investigation is close to the findings of Roche et al.
(1992) Henao et al. (2000). The follicular size > 6
mm reported in this study is in concurrence with the
observations of Krishna mohan et al (2010) and
Satheesh kumar et al (2008). However,
Rajamahendran et al. (1990) reported first postpartum
ovulation as early as 10-15 days postpartum in Bos
indicus cows.
The follicular growth pattern monitored using
an ultrasound scanner during the standing estrus in
ten estrus cycles revealed the occurrence of seven
two wave and the other three shown three wave
cycles with wave emergence on day 1.80 + 0.80 and
12.46+0.50 for two wave cycles, day 1.52 +0.03, 9.60
+0.40 and 15.20 + 0.37 for three wave cycles,
respectively. The two wave pattern (7/10) of follicular
growth observed in the present investigation is in
close agreement with the findings of Figueiredo et
al. (1997), Mayra et al. 1999), Alan et al. (2003),
Borges et al. (2004), Gaur and Purohit (2007) and
Akter et al. (2010) who have reported predominantly
two wave pattern in the estrus cycle in Nelore or Zebu
cows. On the contrary much shorter intervals were
reported by Borges et al.(2001) in zebu crosses,
Rhodes et al.(1995) in cross breed heifers and Malhi
et al. (2005) in Hereford cows.
The mean diameter of the first and second
dominant follicles (10.23 +0.40 and 12.30+ 0.36 mm)
of the two wave recorded in this study were in close
agreement with the findings of Figueiredo et al. (1997)
Mayra et al. (1997) Akter et al. (2010) in Nelore cows.
Contrary to these findings Gaur and Purohit (2007)
observed the lesser average diameter of dominant
follicle size of 8.02 + 0.38 and 9.10 + 0.24 mm in
Nelore cows for the first and second waves,
respectively. However Krishna Mohan et al. (2010)
also recorded higher diameter of (14.6 + 0.12 mm)
than the present study in normal cyclic Sahiwal cows.
It was observed that the first wave dominant follicle
of three wave cycles attained a maximum size of
10.70+0.20 mm with a mean growth rate of 0.87+0.03
mm per day and in the second wave of the dominant
follicle maximum size was 9.80+0.37 mm with growth
rate of 0.77+0.06 per day. The third wave maximum
diameter was 12.80+0.37 mm with a mean growth
rate of 1.46+0.90 mm per day, which is significantly
bigger and faster in growth rate than the first and
second waves in the same estrous cycle. However,
the growth rate of second and third waves were not
significant. This could be due to larger duration of
dominant higher progesterone and low pulsatile
frequency of LH secretion (Wolfenson et al. 2004)
The growth rate of the dominant follicle recorded in
the present study were in agreement with the findings
of Figueiredo et al. (1997). The variation in the
diameter and growth rate of the dominant follicle
reported could be due to inherent characters of the
breeds.
Body score condition (Rhodes et al.1995),
negative energy balance, Insulin like Growth factor,
inhibin and gonadotrophin hormones systemic levels
Rhodes et al. 1997) altered LH pulse frequency and
follicular growth.
In normal two wave cycles, the first wave dominant
follicle did not differ significantly in their size with
ovulatory dominant follicle but it was small in size.
The smaller diameter of first wave dominant follicle
might be due to the fact that the first wave emerged
during the period of higher progesterone production
by the corpus luteum. These findings are in close
agreement with the observations of Figueiredo et al.
(1997), Mayra et al. (1999) and Viana et al. (2000) in
Nelore cows.
In the present study the progesterone
concentration observed during the development of
first follicular wave was between 1.48 to 2.98 ng/ml
which could be a contributing factor for the smaller
size of the dominant follicle of this first wave (Vinoles
et al. 1999).
Perusal of data revealed that, the mean
maximum diameter of the ovulatory follicle was larger
than the diameter of the dominant follicles of previous
waves, which was in agreement with the findings of
Figueiredo et al. (1997) and Mihm et al. (2006). The
growth rate of ovulatory follicle in two wave cycles
was 0.91+0.88 mm per day, was less than first wave
follicle (0.94+0.80 mm per day), which could be due
to lower plasma concentrations of progesterone and
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