Behavioral and hormonal pattern of repeat breeder cows around estrus

Abstract

Repeat breeder (RB) cows were compared with normal (CTRL) ones with respect to behavioral estrus intensity, endocrine patterns and concentrations of plasma estradiol, progesterone and LH around estrus, and ovulation timing. A total of 27 and 31 cycles in 12 RB and 18 CTRL cows, respectively, were synchronized by means of the Ovsynch protocol followed by a single PG injection after 7 days. Behavioral estrus and ovulation were observed in 81.5 and 83.8% of the synchronized cycles in the RB and CTRL cows respectively. The RB and CTRL groups had similar estrus durations of 21.4 and 19.6 h respectively, but estrus was more intense in the RB, as indicated by numerically higher overall activity indexes and higher peak neck activity. The interval from PG injection to estrus onset (considered as proestrus) was 8.2 h shorter in RB than in CTRL cows, at 47.9 and 56.1 h respectively (P!0.007), but the average preovulatory follicle size was similar. The estradiol concentration at peak was numerically higher (21%) and the AUC tended to be higher in the RB cows than in the CTRL cows. LH secretion during the period from 18 to 3 h before the LH peak was also lower in RB than in CTRL cows: 2.5 and 4.6 ng/ml respectively (P!0.01). In conclusion, the behavioral estrus was more intense in the RB cows; nevertheless, short proestrus and subdued LH concentrations before the LH peak, which could impair oocyte competence and development, were first reported in RB cows.

Preovulatory follicle characteristics and oocyte competence in repeat breeder dairy cows

“…In the present study, we found similar P 4 concentrations in the blood of CTL and RB cows at aspiration time, in agreement with our previous findings (Sood et al, 2015). However, earlier studies attributed the reproductive failure in RB cows to increased suprabasal progesterone concentrations during estrus (Båge et al, 2002(Båge et al, , 2003, which we did not find in our present or previous studies (Sood et al, 2015).…”

“…Studies have found that FF E 2 concentrations elicited varied effects on follicles and oocytes: some reported that predominant estrogenic environment in the FF elicited anti-atresia effects and good follicular growth, and enhanced cytoplasmic maturation of the oocytes (Tesarik and Mendoza, 1997), whereas other studies found no beneficial effects on oocytes of higher E 2 (Messinis and Templeton 1987;Dawson et al, 2006). Increased E 2 in the FF, which probably led to increased circulating E 2 around periestrus in the RB cows (Sood et al, 2015), increased the likelihood of achieving pregnancy (Kreiner et al, 1987;Tarlatzis et al, 1993;Teissier et al, 2000) through improvements in sperm transport, fertilization (Hawk, 1983), and embryo quality and viability (Atkins et al, 2013;Jinks et al, 2013). However, increased circulating E 2 , derived from intrafollicular E 2 , might create a favorable uterine environment in RB cows, as was reported previously (Tanabe et al, 1985); however, excessively increased intramolecular E 2 concentrations and E 2 :P 4 ratios might, in turn, result in a relatively more advanced stage of oocyte maturation, and thereby compromise oocyte competence (Kreiner et al, 1987;Tarlatzis et al, 1993;Teissier et al, 2000).…”

“…Fertilization failure (Graden et al, 1968) and embryo mortality (Gustafsson, 1985) are the inherent mechanisms that restrict reproduction under various adverse conditions, of which RB is a pertinent example. There are several documented reasons for subnormal fertility in RB cows; some investigations found endocrine and ovulatory disturbances to be the preponderant reasons (Båge et al, 2002;Saumande and Humbolt, 2005;Bloch et al, 2006;Sood et al, 2015). However, these can be diagnosed from clinical manifestations (e.g., prolonged estrus) or endocrinological assessments, and treated accordingly (López-Gatius et al, 2005).…”

“…However, these can be diagnosed from clinical manifestations (e.g., prolonged estrus) or endocrinological assessments, and treated accordingly (López-Gatius et al, 2005). Nevertheless, other groups of RB cows had normal endocrine and ovulation status, normal genital organs (Sood et al, 2015), and a uterine environment that was favorable for pregnancy (Tanabe et al, 1985). In such cases, determining the exact reason for RB remains a serious challenge, and the etiology remains obscure in 37.8% of the RB cows (Perez-Marin and Espana, 2007).…”

Fertil ve Subfertil Siyah Alaca Düveler Arasında CYP19, ERα, PGR Allel Frekanslarının Dağılımı

“…The rate of pregnancy per artificial insemination (P/AI) is approximately 60-75% in heifers inseminated following estrus detection. Thus, heifers are expected to become pregnant after a maximum two AIs, and heifers with ≥3 AIs can be considered subfertile [7][8][9][10][11] . Subfertile heifers, like repeat breeder cows, cause economic losses in dairy herds because of increased insemination costs, later first calving ages and higher culling rates [5] .…”