Resumption of follicular activity in the early post-partum period of dairy cows

Abstract

Summary. Lactating Friesian dairy cows (2nd\p=n-\4thparity) which calved in spring (N = 7) or autumn (N = 15) were used. Their ovaries were examined by ultrasound scanning and blood samples were obtained daily for progesterone and oestradiol concentrations from the 5th day after calving until the first post-partum ovulation occurred. Five autumn-calving cows selected at random were bled every 15 min over a 6-h period on 1 day each week for 4 weeks after calving to assess the patterns of LH secretion. Follicular development during the post-partum anoestrous period was characterized by the growth and regression of small ( \ m=l e\ 4 mm) and medium-sized (5\ p=n-\ 9 mm) follicles, until a dominant follicle (> 10 mm) was detected. The first detected dominant follicle ovulated in 14 cows, became cystic in 4 cows (all in autumn), and failed to ovulate in 1 cow. It was not possible to detect a dominant follicle in 3 cows due to scanning difficulties. The post-partum interval to detection of the first dominant follicle (mean \ m=+-\ s.d.) was shorter (P < 0\m=.\05) in autumn (6\m=.\8\ m=+-\ 1\m=.\8days) than in spring (20 \m=+-\10\m=.\1days). However, there was no significant difference between the respective intervals to first ovulation (autumn 27\m=.\4\ m=+-\25\m=.\9and spring 27\m=.\3\ m=+-\18\m=.\9 days). Autumncalved cows which had cysts had longer (P < 0\m=.\001) intervals to first ovulation (58\m=.\2\ m=+-\ 23\m=.\5days) than did normal cows (12\m=.\0\ m=+-\2\m=.\5 days). All cows with cysts had twin ovulations at their first post-partum ovulation. A pulsatile pattern of LH secretion was detected in the first week post-partum and LH pulse frequency was 2\p=n-\3 per 6-h period in Weeks 1 and 2 post partum and increased to 5\p=n-\7 pulses per 6-h period in the presence of a dominant or cystic follicle. Concentrations of progesterone in plasma during post-partum anoestrus were usually low (< 0\m=.\2 ng/ml); oestradiol concentrations were also low (<5pg/ml), but higher values (5\p=n-\110 pg/ml) were observed in cows that had a dominant or a cystic follicle.

Parturition to resumption of ovarian cyclicity: comparative aspects of beef and dairy cows

“…This continued growth appears to be owing to lack of positive feedback induced by oestradiol and thus failure of induction of the LH/FSH pre-ovulatory surge, despite increased LH pulse frequency (to an intermediate level). At this time, systemic concentrations of progesterone are low, whereas concentrations of oestradiol are elevated above normal pro-oestrus concentrations (Savio et al, 1990b;Hatler et al 2003), resulting in many cases in strong exhibition of oestrous behaviour by cows in the early phases of a follicular cyst. This is followed by a period of time when there is an absence of oestrous behaviour in the second half of the cysts' lifespan.…”

“…With beef cows in good body condition, the first postpartum dominant follicle to ovulate is generally from wave 3.2 ± 0.2 (~30 days; Murphy et al, 1990), whereas for beef cows in poor body condition there are typically 10.6 ± 1.2 waves of follicular growth before ovulation occurs (~70 to 100 days; Stagg et al, 1995; Figure 3). In the case of dairy cows' ovulation of the first postpartum dominant follicle typically occurs in 30% to 80% of cows, whereas it undergoes atresia in 15% to 60% of cows or becomes cystic in 1% to 5% of cows (Savio et al, 1990b;Beam and Butler 1997;Sartori et al, 2004;Sakaguchi et al, 2004). There is no evidence that lack of FSH or a delayed resumption of ovarian follicle waves are causes of prolonged postpartum anoestrous intervals in either beef (Crowe et al, 1998;Stagg et al, 1998) or dairy cows (Beam and Butler, 1999).…”

Periodicity of Ovarian Follicular Dynamics in Postpartum Cows Demonstrated Using Time-Series Analysis Based on the Maximum Entropy Method.

“…It has been reported that there are three wave of ovarian follicular development occurring at about 7-day intervals in the bovine estrous cycle, and during the early postpartum period of a cow periodical follicular wave can also occur [1,7,8]. Since a long-term observation at a short interval, such as 3 days, would negatively influence the reproductive function of a cow, we introduced 7-day intervals in this study.…”

Ovarian follicle growth dynamics during the postpartum period in Holstein cows and effects of contemporary cyst occurrence

“…Early resumption of ovarian activity is essential for timed cow conception, and thus for achieving an economically acceptable length of the open period. Crucial events in the resumption of ovarian activity postpartum (pp) are the emergence of the 1 st follicular wave (Lucy, 2007) and selection of the dominant follicle (DF) (Mihm and Austin, 2002), which can ovulate, become atretic, or develop into a cyst or non-ovulatory follicle (Savio et al, 1990a;Beam and Butler, 1997;Sakaguchi et al, 2006). Factors affecting the fate of DFs pp are closely related to the metabolic status of animals -for instance, prepartum diet (Cavestany et al, 2009), energy balance (EB) pp (Beam and Butler, 1997), but also parity (Zhang et al, 2010).…”

“…It has been determined that the first follicular growth wave emerges soon after delivery and is independent of the EB of the animal (Butler, 2003). Selection of its DF (> 9 mm) takes place around day 10 pp (Savio et al, 1990a). DFs from the first follicular growth wave ovulate in 30-80% by day 20 (Crowe, 2008), and the interval from parturition to the first ovulation seems to be dependent on parity (Darwash et al, 1997;Tanaka et al, 2008).…”