[Show abstract][Hide abstract] ABSTRACT: The present study aimed to assess the effect of polymorphisms in the tumor necrosis factor α (TNF-α) promoter (A/A, A/G and G/G) and exons (T/T, T/C and C/C) on immune function and reproductive performance in dairy cows. The occurrence of the first postpartum ovulation within 3 weeks in the cows with the TNF-α promoter A/G and G/G genotypes was higher than in the A/A group. Among the different TNF-α exon genotypes, the occurrence of early first postpartum ovulation was higher in the T/C and C/C genotype groups than in the T/T group. Single nucleotide polymorphisms (SNPs) in the TNF-α gene did not affect the rate of artificial insemination (AI) or duration from parturition to next conception (days open). The apoptosis rate of polymorphonuclear leukocytes (PMNs) did not differ among the TNF-α promoter genotypes, but the PMN transmigration rate was significantly higher for the A/A and A/G genotypes than for the G/G genotype. Interleukin 8 (IL-8) mRNA expression in PMNs and peripheral blood mononuclear cells (PBMCs) before culture was significantly higher for the A/A genotype compared with the G/G genotype. There were no significant differences between the genotypes in the mRNA expression of TNF-α, IL-6, IL-1β, and toll-like receptor 4 (TLR4) in PMNs and PBMCs before and 4 h after culture. IL-8 and IL-1β production by PBMCs cultured for 4 h was significantly higher for the animals with the A/A genotype than for those with the G/G genotype. On the other hand, no significant difference was observed in IL-8 and IL-1β production by PMNs among different TNF-α genotypes. Taken together, these results suggest that SNP in the TNF-α gene affects immune function and reproductive performance in dairy cows.
Journal of Reproduction and Development 02/2014; · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: It is well known that the degree of negative energy balance in high-producing dairy cows is the major cause of delayed resumption of the ovarian cyclicity that closely relates to fertility. Recent evidence suggests that the energetic situation during early lactation critically affects nutrient partitioning, metabolism, and the reproductive axis, whereas the effect of energy status during the dry period is widely unknown. The aim of the present study was to investigate the effect of energy status throughout the entire dry period until early lactation on the onset of the ovarian cyclicity. Blood samples were taken in 23 cows from dry off at 8wk before expected parturition to 8wk postpartum for the analyses of metabolites and hormones, and milk samples were obtained 3 times weekly from d 7 of lactation onward to confirm luteal activity and pregnancy by milk progesterone analysis. Energy balance (EB) was measured weekly during the last 6wk of the dry period and every other week after parturition. Liver biopsies were obtained at 8wk before expected calving, within 1 d after calving, and at 4wk postpartum to measure the mRNA abundance of various gluconeogenic enzymes and metabolic hormone receptors. Cows showing luteal activity within 3wk postpartum were defined as ovulatory during the first follicular wave postpartum (OC), whereas cows without luteal activity within 3wk postpartum were defined as anovulatory (AC). Energy balance and, concomitantly, plasma concentrations of glucose, insulin, insulin-like growth factor-1, 3,5,3'-triiodothyronine, and thyroxine were higher in OC than in AC during the dry period. Plasma thyroxine concentrations and body condition score during the postpartum period were higher in OC than in AC. At the mRNA level (19 cows), hepatic insulin receptor decreased from dry off to early lactation, and mRNA of pyruvate carboxylase was highest at parturition and decreased in early lactation in AC only, whereas both parameters remained unchanged in OC. The mRNA abundance of phosphoenolpyruvate carboxykinase-mitochondrial increased from dry off to parturition in both groups, remained high in OC, and decreased again in early lactation in AC. However, none of the investigated gene transcripts differed between OC and AC cows. Thus, ovarian function postpartum appears to be crucially influenced by the energy status during the dry period, which is reflected by timely changes in hepatic mRNA abundance of only a few key metabolic factors in the liver.
Journal of Dairy Science 08/2012; 95(10):5804-12. · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: During recent decades, milk production per cow has increased drastically due to improved management, nutrition, and genetic selection; however, the reproductive performance of high-producing dairy cows has been declining. One of the factors responsible for this low reproductive performance is negative energy balance (NEB). NEB affects the onset of first ovulation in early postpartum cows. It is generally accepted that early first ovulation positively relates to the resumption of normal ovarian function, first service, and conception rate in dairy cows. Hence, delayed first ovulation has a negative impact on subsequent fertility. The metabolic condition of cows in NEB shifts to catabolic metabolism, which in turn causes increased plasma growth hormone and non-esterified fatty acid concentrations and decreased plasma insulin-like growth factor-1, insulin, and glucose concentrations. On the other hand, plasma β-carotene concentrations decrease throughout the dry period and reach their nadir in about the first week postpartum, and this change reflects energy balance during the peripartum period. β-Carotene plays a role independently of vitamin A in the reproductive performance of dairy cows, and the positive relationship between supplemental β-carotene and reproductive function has been demonstrated in many studies during the past decades. However, β-carotene content in corn silage, which is a popular main feed in high-producing dairy cows, is very low. This review describes nutritional factors related to ovulation during the first follicular wave postpartum in dairy cows.
Journal of Reproduction and Development 01/2012; 58(1):10-6. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In peripartum dairy cows, insulin resistance (IR) increases to adjust the direction of energy to lactation after calving. To investigate the effect of prepartum IR on postpartum reproductive performance, the insulin tolerance test (ITT) was applied to 15 cows at 3 weeks (Pre21) and 10 days (Pre10) before the predicted calving date. Blood glucose area under the curve (AUC(glu)) within 120 min after administration of 0.05 IU/kg-BW insulin was calculated. The occurrence of first ovulation, days to first artificial insemination (AI) and first AI conception rate were recorded. Nutritional status postpartum was evaluated by blood chemical analysis. Based on AUC(glu) changes from Pre21 to Pre10, cows were classified into either the AUC-up group (AUC(glu) increase, n=5) or the AUC-down group (AUC(glu) decrease, n=10). There was no difference in the decrease in blood glucose at 30 min after insulin injection between groups, although glucose recovery from 30 to 60 min during the ITT was slow at Pre10 in the AUC-up group. The AUC-up group had a higher number of days to first AI and high glucose, total protein, globulin, γ-glutamyltransferase, triacylglycerol levels and a low albumin-globulin ratio at the 14th day postpartum. The present study infers that prepartum slow glucose recovery rather than insulin sensitivity might increase the potential for subclinical health problems postpartum and thus suppress reproductive performance. During the prepartum transition period, glucose dynamics in the ITT can be considered as a new indicator for the postpartum metabolic status and reproductive performance of dairy cows.
Journal of Veterinary Medical Science 12/2011; 74(4):457-64. · 0.88 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In cows, interferon-tau (IFNT) regulates maternal recognition around days 15-19 after artificial insemination (AI). The present study hypothesized that if key target genes of IFNT are clearly upregulated in earlier stages of pregnancy, these genes could be use as indices of future pregnancy in cows. Therefore, we determined the expression of these genes in peripheral blood mononuclear leukocytes (PBMCs) and polymorphonuclear granulocytes (PMNs) during the maternal recognition period (MRP). Twenty multiparous Holstein cows were subjected to AI on day 0 and categorized into the following groups: pregnancy (Preg, n = 9), embryonic death (ED, n = 5) and non-pregnancy (NP, n = 6). Progesterone levels in the Preg group were higher than those in the NP group on days 12-21. ISG15 and OAS-1 (IFN-stimulated genes: ISGs) mRNA in PBMCs on day 8 was higher in the Preg group than in the NP group, and these mRNAs in PMNs was higher in the Preg group on day 5 than in the NP and ED groups. Interleukin-10 (IL-10, Th2 cytokine) mRNA expression increased on day 8 in the PBMCs of pregnant cows. Tumor necrosis factor α (TNFα, Th1 cytokine) mRNA expression was stable in all groups. In an in vitro cell culture experiment, IFNT stimulated mRNA expression of ISGs in both PBMCs and PMNs. IFNT stimulated IL-10 mRNA expression in PBMCs, whereas IFNT increased TNFα mRNA levels in PBMCs in vitro. The results suggest that ISGs and IL-10 could be responsive to IFNT before the MRP in peripheral blood immune cells and may be useful target genes for reliable indices of pregnancy before the MRP.
Journal of Reproduction and Development 11/2011; 58(1):84-90. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Many metabolic hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and insulin affect ovarian functions. However, whether ovarian steroid hormones affect metabolic hormones in cattle remains unknown. This study aimed to determine the effect of sex steroids on the plasma profiles of GH, IGF-I and insulin and their receptors in the liver and adipose tissues of dairy cows. Ovariectomized cows (n = 14) were randomly divided into four groups: control group (n = 3) was treated with saline on Day 0; oestradiol (E2) group (n = 3), with saline and 1 mg oestradiol benzoate (EB) on Day 0 and 5, respectively; progesterone (P4) group (n = 4) with two CIDRs (Pfizer Inc., Tokyo, Japan) from Day 0; and E2 + P4 group (n = 4) with two CIDRs on Day 0 that were removed on Day 6 and were immediately injected with 1 mg EB. The animals were euthanized after the experiment, and liver and adipose tissues samples were quantitatively analysed using real-time PCR for the expression of mRNA for the GH (GHR), IGF-I (IGFR-I) and insulin (IR) receptor mRNAs. Oestradiol benzoate significantly increased the number of peaks (p < 0.05), pulse amplitude (p < 0.05) and area under the curve (AUC; p < 0.01) for plasma GH; moreover, it increased plasma IGF-I concentration (p < 0.05), but it had no effect on the plasma insulin profile. P4 significantly decreased the AUC (p < 0.01), compared with the control group, whereas it did not affect the number of peaks and the amplitude of GH pulses. P4 + E2 did not affect the GH pulse profile. E2 increased the mRNA expression of GHR, IGFR-I and IR in the liver (p < 0.05), whereas both P4 and E2 + P4 did not change their expressions. Our results provide evidence that the metabolic and reproductive endocrine axes may regulate each other to ensure optimal reproductive and metabolic function.
Reproduction in Domestic Animals 02/2011; 46(5):854-61. · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The decrease in fertility and conception rates of high-producing dairy cows is one of the major negative impacts for today's producers. The recovery of ovarian activity postpartum is affected by the status of immunity, metabolism and reproduction and plays a critical role in subsequent fertility after parturition in the cow. In the present study we investigated the relationships between polymorphisms in genes relating to the above functions and the first postpartum ovulation as a marker of the recovery of ovarian function in the cow. In immune function related-factors, the occurrence of first postpartum ovulation within 3 weeks in the C/C genotypes of tumor necrosis factor α (TNFα) exon (55.4%) and the A/G genotypes of TNFα promoter (55.4%) was significantly higher than that in T/T genotypes of TNFα exon (14.3%) and A/A genotypes of TNFα promoter (14.3%). Moreover, anovulatory cows with the T/T genotype of TNFα exon and the A/A genotype of TNFα promoter tended to have a prolonged days open compared with those of the other genotypes of TNFα polymorphisms. In metabolic function-related factors, ovulatory and anovulatory cows had a different distribution for alleles of the growth hormone receptor, but there were no significant differences in genotype and allele frequency of insulin-like growth factor-I polymorphism. No significant relationships were found between ovarian function after parturition and polymorphisms for reproduction-related genes. In conclusion, polymorphisms of TNFα gene both in exon and promoter regions have a strong association with the early first ovulation within 3 weeks after parturition in the high-producing dairy cow. Taken together, polymorphisms of TNFα gene could be strongly related to early first ovulation after parturition, thus being an effective tool of selection for improving reproductive performance in the high-producing dairy cow.
Journal of Reproduction and Development 11/2010; 57(1):135-42. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to examine the effect of β-carotene supply during the close-up dry period on the onset of first postpartum luteal activity in dairy cows. Twelve cows were supplied with 2000 mg of β-carotene (20 g Rovimix(®) β-Carotene containing 10% β-carotene; DSM Nutrition Japan K.K., Tokyo, Japan) by oral administration daily from day 21 before expected calving date to parturition. Fourteen cows (control) did not receive β-carotene supplementation. Blood samples were obtained on days 21, 14 and 7 before expected calving date and on days 1, 7, 14, 21 postpartum. When the plasma progesterone concentration exceeded 1 ng/ml by day 21 postpartum, luteal activity was assumed to have been initiated. The result showed that serum β-carotene concentrations in the β-carotene cows were higher than in the control cows during the experimental period (p < 0.01). The number of cows with the onset of luteal activity by day 21 postpartum was 9/12 in the β-carotene cows and 4/14 in the control cows (p < 0.05). Retinol, certain metabolic parameters and metabolic hormones concentrations did not differ between β-carotene and control cows. In addition, serum retinol concentration in β-carotene cows without luteal activity was lower than in β-carotene cows with luteal activity (p < 0.05), and serum gamma-glutamyl transpeptidase concentration in β-carotene cows with luteal activity (p < 0.05) and control cows without luteal activity (p < 0.01) was higher than in control cows with luteal activity. In conclusion, β-carotene supply during the close-up dry period may support the onset of luteal activity during early lactation in dairy cows.
Reproduction in Domestic Animals 12/2009; 45(6):e282-7. · 1.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The sex ratio of mammals has previously been shown to be affected by maternal stress. In our previous study, the proportion of female embryos collected from superovulated and artificially inseminated Holstein heifers that were frequently placed in stanchions and subjected to transrectal examinations of the ovaries during the follicular phase tended to be higher than the expected 50%. The goal of the present study was to test the validity of this observation using a greater number of heifers. Superovulated heifers were artificially inseminated at 56 and 72 h after PGF(2alpha) treatment using a single batch of frozen semen. Frequent capture (FC), transrectal examination and/or blood sampling were performed at 4-h intervals from 36 to 76 h after PGF(2alpha) treatment (n=13). Nine heifers were used as the Control (non-treatment). Seven-day-embryos were recovered by uterine flushing. Male and female embryos were separated using the loop-mediated isothermal amplification procedure. The proportion of female transferable embryos in the FC group (67.8%, 78/115) was significantly higher than that in the Control group (51.2%, 43/84, P<0.05). The peak concentration of plasma cortisol during the follicular phase following superovulatory treatment was 20.6 ng/ml in the FC group. These results suggest that subjecting heifers to stress during the follicular phase following superovulatory treatment may increase the female sex ratio of embryos.
Journal of Reproduction and Development 06/2009; 55(5):529-33. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This study was undertaken to produce trophoblastic vesicles (TVs) by using blastocysts of in vitro origin and to estimate the effect on the interestrous interval after transfer of 4 TVs into the uteri of heifers on Day 7. Morphological examination under a stereoscopic microscope revealed that the total formation rate of TVs prepared from IVP expanded blastocysts was 80.5% and that there was no difference in the formation rates of TVs derived from blastocysts between Day 7 (83.5%) and Day 8 (78.5%). After intrauterine transfer of TVs, observation of the corpus luteum (CL) by transrectal ultrasonography together with measurement of the plasma progesterone concentration confirmed that 2 of 4 recipients (50%) had a longer interestrous interval, 33.5 and 35.0 days, while the other 2 recipients had normal cycles, 20.0 and 24.5 days. In the control group transferred D-PBS, all 4 heifers had a normal cycles, 24.0-24.5 days. Consequently, the average number of days after intrauterine transfer of TVs compared with the 2 consecutive cycles just before the treatment was longer than in the controls (6.1 +/- 2.4 days vs. -0.8 +/- 1.1 days, P<0.05). These results indicate that preparation of TVs from blastocysts of in vitro origin is a useable method and that TVs from blastocysts may have the capacity to maintain CL function after intrauterine transfer.
Journal of Reproduction and Development 05/2009; 55(4):454-9. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Insulin and growth hormone (GH) play critical roles in the process of follicular development and maturation. However, the involvement of insulin receptor (IR) and GH receptor (GHR) during follicular development is not well understood. The aim of this study was to investigate the expression of IR and GHR mRNAs in the granulosa cells (GCs) and theca tissues (TCs) of the follicle at different developmental stages (preovulatory dominant follicles, POFs; estrogen-active dominant follicles, EADs; estrogen-inactive dominant follicles, EIDs; and small follicles, SFs), and second, to examine the effects of follicle-stimulating hormone (FSH) and estradiol (E2) on the expression of IR and GHR genes in cultured bovine GCs. Although the concentration of insulin in follicular fluid (FF) was constant at all developmental stages, the GH concentration in FF was significantly increased in the EAD and POF compared with the EID. IR mRNA in GCs and TCs was significantly increased in the POF compared with other follicles. Regarding GHR expression, significant increases of mRNA expression were observed in GCs of EAD compared to those of SF, EID and POF. GHR mRNA in TCs was significantly decreased in the SF compared with other follicles. In cultured GCs, FSH, but not E2, stimulated the expression of IR and GHR genes. Our results suggest that the increase in the expression of GHR may be a turning point for follicles to enter the ovulatory phase during final follicular development and that the insulin system may support the maturation of preovulatory follicles.
[Show abstract][Hide abstract] ABSTRACT: This study was conducted to estimate the effects of kisspeptin-10 on blood concentrations of LH and GH in prepubertal dairy heifers. Heifers received a single injection of 1 mg kisspeptin-10 (n=5) or saline (n=5) intravenously, and serial blood samples were collected at 15-min intervals to analyze the response curves of both LH and GH after injection. Peak-shaped responses were observed for concentrations of LH and GH, and the peaks were observed at 27+/-3 and 75+/-9 min, respectively, after injection, only in heifers injected with kisspeptin-10. These data suggest various possible important links among kisspeptin, the reproductive axis, and also the somatotropic axis in prepubertal Holstein heifers.
Journal of Endocrinology 03/2008; 196(2):331-4. · 4.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Beta-carotene functions independently of vitamin A in the reproductive performance of dairy cows. The concentrations of beta-carotene in plasma decrease during the dry period, and reach a nadir in about the first week postpartum. This coincides with a negative energy balance, which affects the onset of the first ovulation in early postpartum cows. Thus, we hypothesised that plasma beta-carotene concentrations during the peripartum period may affect ovulation in the first follicular wave postpartum in dairy cows. The aim of the present study was to investigate changes in the profiles of plasma beta-carotene concentrations during the peripartum period in ovulatory and anovulatory cows during the first follicular wave postpartum. We used 22 multiparous Holstein cows, which were fed a total mixed ration consisting of grass, corn silage and concentrate, and collected blood samples for beta-carotene and progesterone analysis from week 3 prepartum to week 3 postpartum when the period of day 0-6 after parturition was regarded as the parturient week (week 0). The first ovulation was confirmed using the profile of plasma progesterone concentrations and colour Doppler ultrasound. Thirteen cows ovulated during the first postpartum follicular wave. Parity, the dry-off period, calving interval, mastitis episodes, and actual 305 days' milk yield during the previous lactation, and milk composition in the last month during the previous lactation in this study did not differ between ovulatory and anovulatory cows. Differences in the plasma beta-carotene profile were observed between ovulatory and anovulatory cows. Plasma beta-carotene concentrations at week 3 prepartum were greater in ovulatory cows (2.97+/-0.24 mg/L) than in anovulatory cows (1.53+/-0.14 mg/L; P<0.001), after that its concentrations in ovulatory cows decreased and reached the lowest level at week 1 postpartum, although its concentrations in anovulatory cows remained unchanged. No differences in plasma beta-carotene concentrations between the two groups were observed postpartum. The present study indicates for the first time that the lower beta-carotene concentrations in plasma during the prepartum period is associated with anovulation during the first follicular wave postpartum.
[Show abstract][Hide abstract] ABSTRACT: The aim of our study was to investigate the effects of suckling on reproductive performance and metabolic status of obese (mean body condition score of more than 4.0 on a scale of 1-5) maternal Japanese Black cows during early postpartum period. We used 7 postpartum Japanese Black cattle. Four cows were suckled ad libitum (suckled) until completion of their first artificial insemination (AI), while 3 cows were not suckled at all because they were separated from their calves immediately after parturition (non-suckled). Body weight and plasma concentrations of metabolites and hormones were measured from wk 1 to 9 postpartum. Ovarian activity was detected using plasma progesterone concentration, and all cows received their first AI after application of the Ovsynch protocol at approximately 4 months postpartum. Although body weights of non-suckled cows increased during experimental period (P<0.05), those of suckled cows remained unchanged. Plasma concentrations of glucose of non-suckled cows were higher at wk 2 postpartum (P<0.05) and their levels of non-esterified fatty acid tended to be lower at wk 1 and 2 postpartum compared with suckled cows (P<0.1); however, these differences between groups were not observed with progression of postpartum period. In addition, plasma insulin concentrations of non-suckled cows were higher than those of suckled cows during experimental period (P<0.05). During sampling period (wk 0 to 9 postpartum), onset of normal ovarian cycle was observed in all non-suckled and 2 of 4 suckled cows, and it was delayed in other 2 suckled cows compared with non-suckled cows; however, 3 suckled cows conceived at the first AI after application of the Ovsynch protocol; none of non-suckled cows conceived at this time. Overall, we suggest that suckling seems to reduce increase of body weight after parturition, although it does not improve obesity, and influences conception despite delay in resumption of normal ovarian cyclicity in obese Japanese Black cows.
Journal of Reproduction and Development 02/2008; 54(1):46-51. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aims of this study were 1) to determine whether dairy cows can be induced to ovulate by the treatment with gonadotropin releasing hormone (GnRH) followed by prostaglandin F(2 alpha) (PGF(2 alpha)) during the early postpartum period and 2) to describe their ovarian and hormonal responses according to ovarian status. Cows were divided in two groups and received 10 microg of buserelin followed by 500 microg of cloprostenol 7 days apart starting from 21 (GnRH21, n=7) or around 37 days postpartum (GnRH37, n=7). The groups were further classified according to presence (-CL) or absence (-NCL) of functional corpora lutea (CL) on the day of GnRH treatment (d 0): GnRH21-NCL (n=4), GnRH21-CL (n=3) and GnRH37-CL (n=7). Ovarian morphology was monitored and the concentrations of P(4), E(2), FSH and insulin-like growth factor 1 (IGF-1) were measured. All cows ovulated after administration of GnRH. The P(4) levels of the GnRH21-NCL group from d 0 to d 5 were lower than those of the GnRH21-CL (P<0.05) and GnRH37-CL groups (P<0.01). In contrast, the E(2) levels of the GnRH21-NCL group within d 2 to d 6 were higher (P<0.05) than those of the other groups. Compared with the GnRH37-CL group, the GnRH21-NCL group had more small follicles on d 2 (P<0.05), d 3 (P<0.01) and d 4 (P<0.01) and more large follicles on d 5 (P<0.05). The induced CL and new ovulatory follicles were larger in the GnRH21-NCL group compared with the GnRH21-CL (P<0.001 and P<0.01) and GnRH37-CL groups (P<0.001 and P<0.05). IGF-1 did not differ among the groups. The GnRH21-NCL group had higher FSH levels than the GnRH21-CL (P<0.01) and GnRH37-CL groups (P<0.001) on d 0. Low P(4) and high FSH levels may suggest higher gonadotropin support on the enhanced ovarian morphology of the GnRH21-NCL group. PGF(2 alpha) treatment induced CL regression and subsequent ovulation in 3/4 (75%), 3/3 (100%) and 7/7 (100%) cows in the GnRH21-NCL, GnRH21-CL and GnRH37-CL groups, respectively. In conclusion, a 7-day GnRH-PGF(2 alpha) synchronization protocol can effectively induce dairy cows to ovulate as early as 21 days postpartum, regardless of ovarian status.
Journal of Reproduction and Development 09/2007; 53(4):867-75. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to examine the relationship between characteristics of the lactation curve, on the basis of daily milk yield, and ovulation within 3 wk postpartum as an indicator of early return to luteal activity in dairy cows. Lactation records from 46 lactating Holstein cows between calving and 305 d postpartum were studied. Milk samples were collected twice weekly between d 7 and 100 for later determination of progesterone concentrations. Occurrence of an early first ovulation was determined by an increase in milk progesterone by 3 wk after calving. Milk yield was recorded daily until 305 d postpartum, and average yield was calculated weekly. The lactation curve was characterized by 8 indices on the basis of the weekly average of milk yield as follows: a) first-week milk yield; b) peak milk yield; c) actual 305-d milk yield; d) peak week; e) difference in milk yield between the first week and peak week; f) difference in milk yield between the peak week and last week (43rd week postpartum); g) ratio of increase in milk yield between wk 1 and the week of peak yield; and h) ratio of decline in milk yield between the week of peak yield and the last week. Indices g and h were calculated as linear. The number of cows having ovulated by 3 wk postpartum was 22 (47.8%). The resumption of ovarian cycles with normal luteal phases occurred earlier in ovular cows than in anovular cows (32.0 d vs. 57.1 d). Although total milk yield did not differ between ovular and anovular cows, the ratio of increase in milk yield from the first week to the peak week (index g) in ovular cows was smaller compared with that of anovular cows (1.71 vs. 2.54). In addition, the ratio of increase in milk yield from the first week to the third week postpartum was greater in anovular cows by 3 wk postpartum (ovular = 1.43 +/- 0.23 vs. anovular = 2.32 +/- 0.29). In conclusion, the present study demonstrates that a greater increasing ratio of milk yield during early lactation may delay resumption of ovarian cycles after parturition. Therefore, this study is the first to demonstrate statistically that a smaller increasing ratio of milk yield (index g) during early lactation may have a beneficial effect on the first ovulation by 3 wk postpartum.
Journal of Dairy Science 06/2007; 90(5):2279-82. · 2.57 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to investigate the changing profiles of plasma metabolic hormones during the ovarian cycles of beef and dairy cattle. We used 16 non-pregnant, non-lactating Japanese Black beef cattle (6 heifers and 10 cows; parity=2.3 +/- 0.8) and 12 multiparous Holstein dairy cows (parity=3.0 +/- 0.3). Blood samples for hormonal analysis (growth hormone, GH; insulin-like growth factor-I, IGF-1; insulin; and progesterone, P4) were obtained twice weekly for 40 days before artificial insemination for Japanese Black cattle and from 50 to 100 days postpartum for Holstein cows. Luteal phases were considered normal if the P4 concentrations for at least 3 time points over the course of 7 days remained above 1 ng/ml and at least 2 of the time points were above 2 ng/ml. The patterns of the ovarian cycles were classified into two types (normal or abnormal, such as having prolonged luteal phase and cessation of cyclicity) on the basis of the plasma P4 profiles. The plasma concentrations of IGF-1 in both breeds increased transiently during the preovulatory period when the P4 levels were low and decreased to lower levels during the luteal phase when the P4 levels were high. The plasma concentrations of insulin in the 3(rd) week of normal ovarian cycles when the plasma P4 concentration dropped to less than 1 ng/ml were higher than those at other time points in the Japanese Black cattle, but not in the Holstein cows. The plasma concentrations of GH did not change during the ovarian cycle in either breed. In conclusion, the present study indicates that the plasma IGF-1 concentration increases during the follicular phase (low P4 levels) and decreases during the luteal phase (high P4 levels) in non-lactating Japanese Black and lactating Holstein cattle. The results suggest that ovarian steroids, rather than nutrient status, may be related to the cyclic changes in IGF-1 secretion from the liver in cattle.
Journal of Reproduction and Development 05/2007; 53(2):247-54. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Metabolic hormones affect ovarian function in the cow. However, the relationship between metabolic factors and ovarian function is not clear in the postpartum primiparous cow because they are still growing. The aim of the present study was to investigate in detail the time-dependent profile of the metabolic hormones, metabolites, and milk yields of ovulatory and anovulatory primiparous cows during the first follicular wave postpartum. We used 16 primiparous Holstein cows and obtained blood samples for the profiles of metabolites (glucose; non-esterified fatty acid, NEFA; ketone body; total cholesterol; and aspartate aminotransferase), metabolic hormones (growth hormone, GH; insulin-like growth factor-I, IGF-1; and insulin), and progesterone every other day from 1 to 21 days postpartum. In addition, all ovaries were observed using ultrasound. Dairy milk yield was recorded during the experimental period. In all cows, the first follicular wave postpartum was observed and 6 of the cows ovulated. The plasma glucose (P<0.0001) and IGF-1 (P<0.001) concentrations were lower and the plasma NEFA (P<0.0001) and ketone bodies (P<0.0001) concentrations and daily milk yield (P<0.0001) were higher in the anovulatory cows compared to the ovulatory cows. However, the GH levels, which enhance lipolysis for milk production, insulin and other metabolites did not differ between the two groups. In conclusion, the present study suggests that anovulation of the dominant follicle during the first follicular wave postpartum in primiparous cows is induced by low IGF-1 levels that are similar to those of multiparous cows. In addition, anovulatory cows are likely to mobilize body fat stores for milk production more easily than ovulatory cows.
Journal of Reproduction and Development 03/2007; 53(1):113-20. · 1.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent studies suggest that IGF-I is a crucial regulatory factor in follicular growth during early post-partum period. The aim of the present study was to determine in detail the changing profiles of metabolic and reproductive hormones in relation to ovulation of the dominant follicle (DF) of the first follicular wave post-partum in high-producing dairy cows. Plasma concentrations of related hormones in 22 multiparous Holstein cows were measured from 4 weeks pre-partum to 3 weeks post-partum, and the development of DF was observed with colour Doppler ultrasound. Thirteen cows showed ovulation by 15.2 days post-partum. Anovulatory cows showed higher GH and lower IGF-I levels than those in ovulatory cows during the peri-partum period. Each DF developed similarly, and a clear blood flow in the follicle wall was observed despite ovulation or anovulation. In addition, detailed endocrine profiles were analyzed in 9 out of the 22 cows. Five cows showed an increase in plasma oestradiol-17beta (E2) with follicular growth followed by E2 peak, LH surge and ovulation. In these cows, plasma IGF-I concentrations remained high until 10 days post-partum followed by a gradual decrease. Subsequently, the insulin level increased together with the E2 peak towards ovulation. These profiles were not observed in anovulatory cows. In conclusion, our data strongly support the concept that IGF-I and insulin represent 'metabolic signals' of the resumption of ovarian function post-partum in high-producing dairy cows. Moreover, we provide the first visual evidence that both ovulatory and anovulatory DFs of the first follicular wave post-partum are similarly supplied with active blood flow.