Profiles of Ovarian Steroids, Luteinizing Hormone and Estrous Signs from Luteolysis to Ovulation in Lactating and Non-lactating Dairy Cows

Abstract

Abstract. The aims of the present study were to investigate the profiles of ovarian steroids and luteinizing hormone (LH) and the appearance of estrous signs in relation to luteolysis and ovulation in lactating and non-lactating cows and to examine the influence of lactation on those observations. Five lactating (daily milk yield of 28.4 ± 3.2 kg; mean ± SD) and five nonlactating cycling Holstein cows were examined. Their ovaries were monitored by ultrasonography daily during one estrous cycle. Blood samples were collected daily and then at 3-h intervals after luteolysis until ovulation. Estrous signs in terms of behavior, the vulva and the vagina were checked at 8-h intervals after luteolysis until ovulation. Profiles of progesterone, estradiol-17β and LH did not differ between the groups. There were no differences in the interval from luteolysis to ovulation (4.6 ± 0.5 and 4.2 ± 0.8 days) and the interval from the estradiol-17β peak to ovulation (34.2 ± 4.5 and 30.6 ± 3.9 h) between lactating and non-lactating cows. The interval from the peak of the LH surge to ovulation was 27 h in all cows examined. Appearance of estrous signs did not differ between the groups. The vaginal estrous signs were observed conspicuously in all cows examined, but the behavioral signs were not observed in 20.0% of the cows. The duration of behavioral signs (41.3 ± 23.6 h) was shorter (P<0.05) than that of the vagina (68.9 ± 25.4 h). These results imply that lactation might not interfere with the hormonal profiles from luteolysis to ovulation.

Possible causes and treatment strategies for the estrus and ovulation disorders in dairy cows

“…However, the profiles of E2, P4, and LH in plasma collected at 3-h intervals during the period from natural luteolysis to ovulation did not differ significantly between the lactating and non-lactating dairy cows [27] (Table 1). In this study, the lactating cows were in their mid-lactation period (>80 days postpartum) and had a good nutritional status [27]. It is likely that lactation itself did not disturb the periovulatory endocrine events and that lactating cows could maintain normal estrus cyclicity.…”

“…Previous studies have reported that plasma E 2 concentration around estrus is correlated with the intensity of estrus behavior and duration of estrus [ 25 , 26 ]. To determine the characteristics of ovarian and endocrine profiles during the estrus cycle and periovulatory period in lactating dairy cows, the development of follicles and corpus luteum, plasma concentrations of estradiol-17β (E 2 ), progesterone (P 4 ), and LH, and timing of ovulation were compared with those of non-lactating dairy cows [ 27 , 28 ]. In estrus cycles with two follicular waves, the maximal diameter of the ovulatory follicle is greater in lactating cows than in non-lactating cows [ 28 ].…”

“…An increase in the size of ovulatory follicles in lactating dairy cows has been reported previously [ 29 , 30 ]. However, the profiles of E 2 , P 4 , and LH in plasma collected at 3-h intervals during the period from natural luteolysis to ovulation did not differ significantly between the lactating and non-lactating dairy cows [ 27 ] ( Table 1…”

“…). In this study, the lactating cows were in their mid-lactation period (> 80 days postpartum) and had a good nutritional status [ 27 ]. It is likely that lactation itself did not disturb the periovulatory endocrine events and that lactating cows could maintain normal estrus cyclicity.…”

Influence of Contact Force on Electrochemical Responses of Redox Species Flowing in Nitrocellulose Membrane at Micropyramid Array Electrode

“…LH temporally and rapidly increases just before ovulation in what is called the LH surge. 2 The detection of the LH surge is very important to estimate the optimal artificial insemination period and to improve the conception rate. Measuring estrogen and progesterone levels is useful to estimate the date of calving, 3,4 which helps farmers in achieving safe calving.…”