Publications (15) View all
-
Article: Effect of duration of the growing phase of ovulatory follicles on oocyte competence in superstimulated cattle.
[show abstract] [hide abstract]
ABSTRACT: In the present study, we tested the hypotheses that oocyte competence is compromised by a longer duration of follicular growth and that it is not affected by FSH starvation. Cows were allocated to short FSH (n=14), FSH starvation (n=13) and long FSH (n=13) groups. The first two groups were given eight doses of FSH, whereas the third group was given 14 doses of FSH, starting from the day of wave emergence (Day 0). A progesterone-releasing device (controlled internal drug release; CIDR) was placed intravaginally at the start of the experiment in all groups. The short FSH group was given prostaglandin (PG) F on Day 3, whereas the two other groups received PGF on Day 6. In all cows, the CIDR was removed at the time of PGF treatment; porcine (p) LH was given 24h after CIDR removal and cows were inseminated 24 and 36h later. Reproductive tracts were collected 4 days after insemination and ova and/or embryos were cultured for ≥6 days. The FSH starvation group had fewer ovulations (P=0.001), and ova and/or embryos (P<0.05). No difference in embryo quality was detected between long and short FSH groups at 7, 9 or 10 days after artificial insemination. In conclusion, oocyte competence was not altered by the duration of the follicular growth phase in superstimulated cows, whereas FSH starvation substantially reduced the ability of superstimulated follicles to ovulate.Reproduction Fertility and Development 03/2013; 25(3):523-30. · 2.11 Impact Factor -
Article: Short communication: Effects of serum obtained from dairy cows with low or high body condition score on in vitro embryo development.
[show abstract] [hide abstract]
ABSTRACT: The objective of the study was to determine whether the serum obtained from animals differing in body condition score (BCS) affects in vitro embryo development. After in vitro fertilization, serum obtained from dairy cows of either low (L-BCS; 2.1 ± 0.14 on a scale of 1 to 5) or high BCS (H-BCS; 4.0 ± 0.0), or commercially available bovine serum (control) was added at 5% concentration to the in vitro culture medium. Use of serum obtained from H-BCS cows increased the cleavage rates compared with control serum at both 24 and 48 h after in vitro fertilization (78.3 vs. 71.9% and 79.9 vs. 75.1%, respectively), whereas use of serum obtained from L-BCS cows increased the blastocyst rate compared with control serum at 7 d (23.8 vs. 19.1%), but this difference was not evident at 8 or 9 d after in vitro fertilization. As nonesterified fatty acid concentrations were highest in control serum, followed by serum from L-BCS and H-BCS cows (621, 559, and 272 μEq/L, respectively), a high concentration of nonesterified fatty acids might adversely affect the very early stages of embryo development, and its negative effects might be greater immediately after fertilization compared with developmental stages after morula formation. Our findings also suggest that factors promoting early stage embryo development do not necessarily promote blastocyst development. Serum obtained from animals under different physiological conditions may be used for in vitro embryo culture to study the effects of nutritional management of dairy cattle on embryo development.Journal of Dairy Science 01/2013; · 2.56 Impact Factor -
Article: Factors affecting reproductive performance in high milk-producing Holstein cows.
[show abstract] [hide abstract]
ABSTRACT: Although the number of dairy farms is decreasing, that of large farms is increasing in Japan. Milk production in Japanese dairy cows has increased from 62 kg/year to 88 kg/year over the last 2 decades. However, Japanese dairy cows are experiencing a sustained decline in reproductive performance, calving intervals, and days open; further, the number of inseminations required for conception have increased, and the conception rate has decreased. In order to improve fertility in high milk-producing dairy cows, it is necessary to evaluate their reproductive characteristics. In this study, the postpartum body condition score (BCS) was remarkably low, and the functional recovery of reproduction was consequently delayed. Moreover, the results indicate that the estrus duration varies among individual cows. However, it is possible to improve the conception rate by inseminating cows 8-12 h after the onset of estrus. Reproductive management systems suitable for the current dairy farming system with large herd sizes are required.Journal of Reproduction and Development 01/2010; 56 Suppl:S61-5. · 1.46 Impact Factor -
Article: Effect of length of progesterone exposure during ovulatory wave development on pregnancy rate.
[show abstract] [hide abstract]
ABSTRACT: The objective was to determine the effects of the duration of progesterone exposure during the ovulatory wave on fertility (pregnancy rate) in beef cattle. We tested the hypothesis that short-progesterone exposure during the growing and early-static phase of the ovulatory follicle (analogous to the ovulatory wave of 3-wave cycles) is associated with higher fertility than a longer duration of exposure (analogous to the ovulatory wave of 2-wave cycles). Three to 5 days after ovulation, beef heifers (n = 172) and suckled beef cows (n = 193) were given an intravaginal progesterone-releasing device (CIDR) and 2.5 mg estradiol - 17β +50 mg progesterone im to induce a new follicular wave. Cattle were allocated to short- or long-progesterone exposure groups (for 3 and 6 d after wave emergence, respectively) after which prostaglandin F(2α) was administered and CIDR were removed. Forty-eight hours later, all cattle were given 12.5 mg pLH and artificially inseminated (AI) with frozen-thawed semen. The diameter of the two largest follicles and the corpus luteum were measured by transrectal ultrasonography at CIDR removal, insemination, and 36 h after insemination. Pregnancy diagnosis was done ultrasonically 38 and 65 d post-AI. There was no difference in pregnancy rates in short- vs long-progesterone exposure in heifers (53 vs 47%, P = 0.44) or cows (63 vs 58%, P = 0.51). However, the diameter of the ovulatory follicle at CIDR removal and AI was smaller in short- than in long-progesterone groups (P < 0.02), and larger in cows than in heifers (P < 0.006). In conclusion, short-progesterone exposure during the growing and early-static phase of the ovulatory follicle (similar to 3-wave cycles) was not associated with higher fertility than a longer progesterone exposure (similar to 2-wave cycles).Theriogenology 01/2012; 77(2):437-44. · 1.96 Impact Factor -
Article: 77 reproductive performance of dairy cows differing in the interval from calving to the first ovulation in the postpartum period.
[show abstract] [hide abstract]
ABSTRACT: In recent years, reproductive performance of dairy cows has declined worldwide. The reproductive characteristics of dairy cows should be evaluated to improve their fertility. Dochi et al. (2010) had reported that dairy cows that exhibited early first ovulation gave a low milk yield, had an early recovery of body condition score (BCS) in the postpartum period and a shorter number of days open. The objective of this study was to evaluate the effect of BCS on the functional recovery of reproduction after the birth of the calves. In this study, lactating Holstein cows were placed in free-stall housing equipped with an automatic milking system. The data presented in this study were collected from 48 cows that had calved between December 2007 and October 2010 with an average parity of 3.4 (range 2-6). The reproductive performance and the BCS during the different intervals between calving and the first ovulation were analysed using ANOVA. The conception rate at the first service was 38.1%. The average milk yield (305 days) was 12299kg. The first ovulation and oestrus were determined by ultrasonography. The results of the different intervals to the first ovulation are presented in Table 1. The average interval from the start of days in milk (DIM) to the first ovulation, first oestrus and first service; the number of days open; the number of services per conception and the milk yield (kgday(-1), by 90 DIM) were 37.4, 54.7 and 110.3 days; 168.2 days open; 2.5 times; and 42.1kgday(-1), respectively. The cows that exhibited early first ovulation (≤21 DIM) in the postpartum period had significantly shorter intervals between the start of DIM and the first oestrus (P<0.01). However, the days to first service, the number of days open, the number of services per conception and the milk yield (kgday(-1), by 90 DIM) did not differ significantly. The BCS in the peripartum period of different intervals to the first ovulation decreased from 3.1 to 2.4 by 150 DIM. This study showed that average BCS of preparturient 50-10 DIM is 3.0. Moreover, the average BCS of parturition is declining to 2.5 (parturition from 70 to 150 DIM). The cows became pregnant after an increase in the BCS (>150 DIM). In conclusion, these results suggest that the delay to the first ovulation in the postpartum period tended to have delayed the oestrus expression in the cows. Moreover, the low level of BCS in the peripartum period, regardless of the number of days of the first ovulation and the first oestrus, potentially influenced the prolongation in the number of days open. To improve the fertility of the cows, it is important to elucidate the factors affecting the fluctuations in the BCS during the peripartum period.Reproduction Fertility and Development 12/2011; 24(1):151. · 2.11 Impact Factor
