Japanese Black Research Articles

129 Embryo Production from Fully Grown and Growing Stage Oocytes in Japanese Black Calves

Before fattening of Japanese Black female calves, the ovaries are sometimes removed and discarded. Production of embryos from the oocytes residing in such ovaries is beneficial for the rescue of genetic resources. The aim of this study was to establish an embryo production system using oocytes collected from the ovaries of calves just before fattening and to investigate the correlation between the developmental competence of oocytes and the onset of puberty. Ovaries were collected from Japanese Black calves (9.5 ± 0.1 months old, n = 30, 3 replicates) in a fattening farm and separated according to the presence or absence of corpus luteum as the indicator of puberty (CL+ and CL– groups, respectively). Immature fully grown oocytes (IM oocytes), ~120 μm in diameter, were aspirated from follicles of 2 to 6 mm in diameter (CL+; n = 132, CL–; n = 41) and cultured for 22 to 23 h for maturation (IVM). After in vitro fertilization (IVF) for 6 h (designated Day 0), the oocytes were cultured for 9 days (in vitro culture, IVC) (Matoba et al. 2014 J. Dairy Sci. 97, 743-753). Growing oocytes, ~100 μm in diameter, were also collected by dissecting the follicles smaller than 1 mm in diameter. The growing oocytes were cultured for 14 days on membrane inserts for in vitro growth (IVG) (Hirao et al. 2013 Biol. Reprod. 89, 1-11). Then, IVG oocytes (CL+; n = 29, CL–; n = 32) were subjected to IVM, IVF, and IVC. Presumptive zygotes were cultured individually in microwells in culture dishes. Mitochondrial DNA (mtDNA) copy numbers (COX1 gene) of oocytes were examined (Takeda et al. 2010 Mitochondrion 10, 137-142). A comparison was made between the oocytes derived from calf ovaries and those of oocytes collected from cow ovaries by transvaginal ovum pick-up or by aspiration of the ovaries obtained at a local slaughterhouse. In IM oocytes, the rate of embryos developed to the blastocyst stage on Day 7 to 9 was higher in the CL+ group than in the CL– group (38.9 ± 2.6 v. 10.0 ± 7.1%, respectively; P < 0.05, t-test). However, IVG oocytes were compared, there was no significant difference in the blastocyst formation rate between the CL+ or CL– groups (34.7 ± 5.2 v. 19.8 ± 10.1%, respectively). The mtDNA copy numbers of matured oocytes were similar between IM and IVG oocytes irrespective of the maturity of the donor animals. In conclusion, we demonstrated the possibility of embryo production by IVM/IVF/IVC using fully grown and growing oocytes that are present in the ovaries of calves before fattening. Puberty positively affected the developmental competence of IM oocytes but the effect was not significant in IVG oocytes. Utilisation of both fully grown oocytes and growing oocytes may double the chance of rescuing genetic resources of high-breeding-value calves. This study was partly supported by grants from the Ito Foundation. We thank staff at Mie-Katoubokujou for allowing access to calves’ ovaries.

Gas Chromatography-Mass Spectrometry for Metabolite Profiling of Japanese Black Cattle Naturally Contaminated with Zearalenone and Sterigmatocystin.

The objective of this study was to evaluate the metabolic profile of cattle fed with or without zearalenone (ZEN) and sterigmatocystin (STC)-contaminated diets using a gas chromatography-mass spectrometry metabolomics approach. Urinary samples were collected from individual animals (n = 6 per herd) from fattening female Japanese Black (JB) cattle herds (23 months old, 550–600 kg). Herd 1 had persistently high urinary ZEN and STC concentrations due to the presence of contaminated rice straw. Herd 2, the second female JB fattening herd (23 months old, 550–600 kg), received the same dietary feed as Herd 1, with non-contaminated rice straw. Urine samples were collected from Herd 1, two weeks after the contaminated rice straw was replaced with uncontaminated rice straw (Herd 1N). Identified metabolites were subjected to principal component analysis (PCA) and ANOVA. The PCA revealed that the effects on cattle metabolites depended on ZEN and STC concentrations. The contamination of cattle feed with multiple mycotoxins may alter systemic metabolic processes, including metabolites associated with ATP generation, amino acids, glycine-conjugates, organic acids, and purine bases. The results obtained from Herd 1N indicate that a two-week remedy period was not sufficient to improve the levels of urinary metabolites, suggesting that chronic contamination with mycotoxins may have long-term harmful effects on the systemic metabolism of cattle.

Identification and Characterization of Volatile Components Causing the Characteristic Flavor of Wagyu Beef (Japanese Black Cattle).

To clarify the characteristic sweet aroma of Wagyu (Japanese Black Cattle), aroma extraction dilution analysis (AEDA) was applied to the volatile fractions of Wagyu and Australia beefs. Some 20 odor-active peaks were detected, and 17 odorants were identified or tentatively identified. Among the perceived odorants, most of them were newly identified from the Wagyu beef. The main constituents of the potent odorants were aldehydes and ketones, which are known as the degradation products of polyunsaturated fatty acids that were significantly included in the lipids of the Wagyu. In addition, the most potent odorant was trans-4,5-epoxy-(E)-2-decenal, which is known to be the oxidation product of polyunsaturated acids, such as linoleic acid and arachidonic acid, that were significantly included in the lipids of the Wagyu. Accordingly, these findings strongly suggested that the kind of fatty acid constituting lipids of the Wagyu plays an important role in the formation of the characteristic aroma of the Wagyu beef.

Different thermotolerances in invitro-produced embryos derived from different maternal and paternal genetic backgrounds.

The present study evaluated the effects of genetic backgrounds on the developmental competence and thermotolerance of bovine invitro-produced (IVP) embryos. First, Holstein (Hol) and Japanese Black (JB) oocytes were fertilized with sperm from Hol, JB and a thermotolerant breed (Brahman), and invitro development was evaluated when the embryos were exposed to heat shock on Day 2 (Day 0=day of fertilization). Sperm genetic backgrounds affected the developmental competence in controls (P<0.05). Second, the effect of sperm pre-incubation for 4h on subsequent invitro fertilization was assessed using different sperm genetic backgrounds. The pre-incubation of sperm did not decrease the embryonic development regardless of the breed of the sperm. A milder heat shock (40.0°C) effect on parthenotes (Hol and JB) and IVP embryos were evaluated. JB parthenotes showed developmental arrest after Day 4, and the rate of development to the blastocyst stage decreased by heat shock, but not in Hol parthenotes. Heat shock decreased developmental competence after cleavage of IVP embryos regardless of genetic background. The thermotolerance of IVP embryos would be controlled by both maternal and paternal factors but genetic involvement was still unclear. Further evaluation is needed to reveal the genetic contribution to thermotolerance.

Genetic analysis of semen production traits of Japanese Black and Holstein bulls: genome-wide marker-based estimation of genetic parameters and environmental effect trends.

The semen production traits of bulls from 2 major cattle breeds in Japan, Holstein and Japanese Black, were analyzed comprehensively using genome-wide markers. Weaker genetic correlations were observed between the 2 age groups (1 to 3 yr old and 4 to 6 yr old) regarding semen volume and sperm motility compared with those observed for sperm number and motility after freeze-thawing. The preselection of collected semen for freezing had a limited effect. Given the increasing importance of bull proofs at a young age because of genomic selection and the results from preliminary studies, we used a multiple-trait model that included motility after freeze-thawing with records collected at young ages. Based on variations in contemporary group effects, accounting for both seasonal and management factors, Holstein bulls may be more sensitive than Japanese Black bulls to seasonal environmental variations; however, the seasonal variations of contemporary group effects were smaller than those of overall contemporary group effects. The improvement of motilities, recorded immediately after collection and freeze-thawing, was observed in recent years; thus, good management and better freeze-thawing protocol may alleviate seasonal phenotypic differences. The detrimental effects of inbreeding were observed in all traits of both breeds; accordingly, the selection of candidate bulls with high inbreeding coefficients should be avoided per general recommendations. Semen production traits have never been considered for bull selection. However, negative genetic trends were observed. The magnitudes of the estimated h were comparable to those of other economically important traits. A single-step genomic BLUP will provide more accurate predictions of breeding values compared with BLUP; thus, marker genotype information is useful for estimating the genetic merits of bulls for semen production traits. The selection of these traits would improve sperm viability, a component related to breeding success, and alleviate negative genetic trends.

自然環境としてのわが国の大型野生動物 : ニホンツキノワグマとニホンイノシシ : 「森林と国土論 : 地理学からのアプローチ」 : 昭和62年度秋季学術大会シンポジウム

自然環境としてのわが国の大型野生動物 : ニホンツキノワグマとニホンイノシシ : 「森林と国土論 : 地理学からのアプローチ」 : 昭和62年度秋季学術大会シンポジウム

Microsatellite markers for animal identification and meat traceability of six beef cattle breeds in the Chinese market

Microsatellite markers have been shown to be a useful tool in individual identification and meat traceability. Aiming at developing a genetic tracing system for beef cattle breeds in the Chinese market, this study identified a set of 16 specific microsatellite markers within six breeds, including Japanese Black, Anduo yak, Limousin, Jiaxian Red, Nanyang Yellow and Luxi Yellow. A total of 180 alleles have been detected with an average number of 11.2 per locus, and the average polymorphism information content (PIC) is 0.7696 for all loci. The 16-loci set could successfully distinguish all the individuals of the six breeds. When the six most polymorphic markers were chosen for each breed, the matching probability (MP) value was found to be about seven in one million, excluding the extremely high value in Limousin. As the number of markers increased, the MP value was gradually lowered, and the accuracy was also enhanced. Meanwhile, the traceability validation test was conducted with the seven most polymorphic markers (ETH10, ETH225, ILSTS006, INRA032, INRA035, INRA037 and TGLA122), the conforming probabilities of genotypes for 28 blood and corresponding tissue samples were 100%. The results of this study could partly prevent the food fraud incidence in the Chinese market, and they also showed further evidence in the applications of genetic markers to meat traceability based on animal identification to ensure food safety.

Estrous detection by monitoring ventral tail base surface temperature using a wearable wireless sensor in cattle

In the present study, the ventral tail base surface temperature (ST) was monitored using a wearable wireless sensor for estrus detection in cattle. Relationships among ST, behavioral estrus expression, ovulation, and changes in hormone profiles during the estrous cycle were examined. Holstein Friesian or Japanese Black female cattle were used in summer (August–September), autumn (October–November) and winter (January–February; three animals per season). On Day 11 of the estrous cycle (Day 0=the day of ovulation), the sensor was attached to the surface of the ventral tail base and ST was measured every 2min until Day 11 of the next estrous cycle. Hourly maximum ST values were used for analysis. To exclude circadian rhythm and seasonal effects, ST changes were expressed as residual temperatures (RT=actual ST − mean ST for the same hour on the previous 3days). Obvious circadian rhythms of the ST were observed and daily changes in the ST significantly differed among seasons. There was no significant seasonal difference, however, in the RT. The mean RT increased significantly ∼24 compared with ∼48h before ovulation. The mean maximum RT was 1.27±0.30°C, which was observed 5.6±2.4h after the onset of estrus, 2.4±1.3h before LH peak, and 26.9±1.2h before ovulation. The ST of the ventral tail base could be monitored throughout the estrous cycle and could detect a substantial change around the time of expression of behavioral estrus. Calculation and analysis of the RT could be useful for automatic estrous detection.

Abundance of beige and brown adipocyte markers in different adipose depots of cattle at 26 months of age

Activity of brown and beige adipocytes could contribute to breed differences in fat deposition. Therefore, we compared the abundance of markers for adipocyte types in steers from three cattle breeds differing in fat deposition (Japanese Black, Holstein, Charolais). Markers for white (leptin (LEP)), beige (transmembrane protein 26 (TMEM26), uncoupling protein 1 (UCP1)), and brown adipocytes (Zic family member 1 (ZIC1), UCP1) were analysed by quantitative reverse transcription PCR in subcutaneous fat (SCF), intramuscular fat (IMF), intermuscular fat (IRMF), perirenal fat (PF) and visceral fat (VF). LEP messenger RNA (mRNA) was less abundant in VF compared with other depots (P&lt;0.05). TMEM26 was weakly but evenly expressed in all depots in all animals, whereas UCP1 mRNA showed higher individual variation in some depots. ZIC1 was not detectable in VF and PF but abundant in SCF, IMF and even more abundant in IRMF (P&lt;0.05). No significant breed differences were detected. Using antibodies against UCP1, TMEM26 and ZIC1, we demonstrated that fat depots of 26-month-old cattle still comprise different adipocyte types. However, our results did not support the hypothesis that higher energy expenditure associated with higher abundance or activity of beige or brown adipocytes contributed to differences in fat deposition.

Cattle with the BoLA class II DRB3*0902 allele have significantly lower bovine leukemia proviral loads.

The bovine MHC (BoLA) class II DRB3 alleles are associated with polyclonal expansion of lymphocytes caused by bovine leukemia virus (BLV) infection in cattle. To examine whether the DRB3*0902 allele, one of the resistance-associated alleles, is associated with the proviral load, we measured BLV proviral load of BLV-infected cattle and clarified their DRB3 alleles. Fifty-seven animals with DRB3*0902 were identified out of 835 BLV-infected cattle and had significantly lower proviral load (P<0.000001) compared with the rest of the infected animals, in both Japanese Black and Holstein cattle. This result strongly indicates that the BoLA class II DRA/DRB3*0902 molecule plays an important immunological role in suppressing viral replication, resulting in resistance to the disease progression.

Genetic analysis of semen production traits of Japanese Black and Holstein bulls: genome-wide marker-based estimation of genetic parameters and environmental effect trends

Genetic analysis of semen production traits of Japanese Black and Holstein bulls: genome-wide marker-based estimation of genetic parameters and environmental effect trends

100 FACTORS AFFECTING PREGNANCY RATES IN THE TRANSFER OF IN VITRO-PRODUCED JAPANESE BLACK CATTLE EMBRYOS

Despite the rapid expansion of in vitro embryo production (IVP) technology for genetic improvement in the cattle industry in the last decades, pregnancy rates by the transfer of IVP embryos are still lower than those derived from in vivo-produced embryos. The objective of this study was to analyse factors affecting pregnancy rates after the transfer of IVP Japanese Black cattle embryos under farm conditions. Holstein heifers (n = 4,475) and cows (n = 8,541) were selected as recipients. Most cows (80%) were managed in tie-stall barns and most heifers (80%) were managed in pens. Embryo transfers were performed for 9 years, from 2004 to 2012. The embryos were produced from oocytes derived from a local abattoir and semen from 14 proven bulls by the Livestock Improvement Association of Japan (Hamano and Kuwayama 1993 Theriogelogy 39, 703–712). The fresh IVP embryos (quality; IETS code 1) that reached the blastocyst stage after 7 to 8 days (insemination = Day 0) were transported by an airplane (2 h) and subsequently by a car (1.5 h). Embryos were non-surgically transferred to each recipient on Day 7 to 9 of their natural oestrous cycle on farms. Pregnancy was diagnosed on Day 40 to 60 after oestrus. Pregnancy results were statistically analysed using the GLM procedures of SAS. The following variables were included in the model: recipient parity (0, 1, 2, or 3), day (7, 8, or 9) of the oestrous cycle at the time of embryo transfer, oestrus behaviour (increased activity observed by farmers), presence of mucus at oestrus, presence of blood after oestrus, and year (1, 2, 3, 4, 5, 6, 7, 8, or 9) and season (April–June as spring, July–September as summer, October–December as fall, or January–March as winter) of embryo transfer. The Bonferroni correction was used to counteract the problem of multiple comparisons. Heifers had significantly higher pregnancy rates than cows (51.0% v. 37.9%, respectively; P &lt; 0.01), and first parity cows had higher pregnancy rates than third parity cows (42.9% v. 35.7%, respectively; P &lt; 0.01). Pregnancy rates were significantly higher in recipients that received an embryo transfer on Day 8 of their oestrous cycle, than on Day 7 (46.6% v. 42.4%, respectively; P &lt; 0.01). Recipients without oestrus behaviour had higher pregnancy rates than those with oestrus behaviour (46.3% v. 43.4%, respectively; P &lt; 0.01). The presence of mucus and/or blood after oestrus and the season of transfer were not found to significantly affect pregnancy rates. The results of this study indicated that performing IVP embryo transfers on Day 8 of a recipient’s oestrous cycle will improve the pregnancy rate, season does not have an effect on pregnancy rate, and the detection of oestrus by monitoring increased activity is not always reliable and instead should be determined by multiple symptoms on farm conditions.

Histopathological changes in the pancreas of cattle with abdominal fat necrosis.

The association between pancreatic disorder and abdominal fat necrosis in cattle remains unclear. The pancreases of 29 slaughtered cattle with or without fat necrosis were collected to investigate pathological changes. Japanese Black (JB) cattle were classified into the FN group (with abdominal fat necrosis; n=9) and N group (without fat necrosis; n=5). The pancreases were also collected from 15 Holstein Friesian (HF) cows. All JB cattle showed high body condition scores. Regarding the pathological findings, fatty pancreas which involves adipocyte infiltration into the pancreas and fat necrosis (saponification) were observed in 25 and 27 cases, respectively. Immunohistochemical staining with anti-Iba-1 antibody showed large numbers of macrophages surrounding the saponified fat in the pancreas. CD3-positive T cells were significantly more common in the pancreas of both the FN and N groups compared with the HF group (P<0.05). Furthermore, fibrosis in the pancreas exhibited a correlative tendency with the formation of necrotic fat mass in the peritoneal cavity (P<0.1). These results indicate that obesity leads to increased severity of pancreatic disorder, including fatty pancreas and pancreatitis. The pathological lesions in the pancreas may play a key role in abdominal fat necrosis through the inflammatory process.

Curious Japanese black: Shaping the identity of Dutch imitation lacquer

Curious Japanese black: Shaping the identity of Dutch imitation lacquer

Long-Term Survey of Cadmium and Lead Contamination in Japanese Black Bears Captured in Iwate Prefecture, Japan

Cadmium and lead were measured in liver and kidney samples of 242 Japanese black bears (Ursus thibetanus japonicus) captured from 1999 to 2014 from two local populations in Japan. The median concentration of cadmium was 0.54 (mean: 0.80) mg/kg-w.w. in liver and 7.7 (mean: 11.8) mg/kg-w.w. in kidney. The median concentration of lead was 0.24 (mean: 0.40) and 0.21 (mean: 0.32) mg/kg-w.w. in liver and kidney, respectively. Bears in the Kita-ou local population had higher concentrations of cadmium and lead than those in the Kitakami Highlands local population. No chronological change was observed in cadmium levels in tissues, but the percentage of bears whose lead levels exceeded 0.5mg/kg-w.w. has been decreasing in recent years. Countermeasures against lead poisoning in wildlife, which were instituted in 2002, may have contributed to the decrease in lead contamination of the Japanese black bear.

Differences in Circulating microRNAs between Grazing and Grain-Fed Wagyu Cattle Are Associated with Altered Expression of Intramuscular microRNA, the Potential Target PTEN, and Lipogenic Genes.

We aimed to understand the roles of miRNAs in the muscle tissue maturation and those of circulating microRNAs (c-miRNAs) in beef production of Japanese Black (JB) cattle (Wagyu), a breed with genetically background of superior intermuscular fat depot, by comparing different feeding conditions (indoor grain-feeding vs. grazing on pasture). The cattle at 18 months old were assigned to pasture feeding or conventional indoor grain feeding conditions for 5 months. Microarray analysis of c-miRNAs from the plasma extracellular vesicles led to the detection of a total of 202 bovine miRNAs in the plasma, including 15 miRNAs that differed between the feeding conditions. Validation of the microarray results by qPCR showed that the circulating miR-10b level in the grazing cattle was upregulated compared to that of the grain-fed cattle. In contrast, the levels of miR-17-5p, miR-19b, miR-29b, miR-30b-5p, miR-98, miR-142-5p, miR-301a, miR-374b, miR-425-5p, and miR-652 were lower in the grazing cattle than in the grain-fed cattle. Bioinformatic analysis indicated that the predicted target genes of those c-miRNAs were enriched in gene ontology terms associated with blood vessel morphogenesis, plasma membrane, focal adhesion, endocytosis, collagen, ECM-receptor interaction, and phosphorylation. In the grazing cattle, the elevation of miR-10b expression in the plasma was coincident with its elevation in the longissimus lumborum (LL) muscle. Expression of bovine-specific miR-2478, the most plasma-enriched miRNA, tended to be also upregulated in the muscle but not in the plasma. Furthermore, grazing caused the downregulated mRNA expression of predicted miR-10b and/or miR-2478 target genes, such as DNAJB2, PTEN, and SCD1. Thus, the feeding system used for JB cattle affected the c-miRNAs that could be indicators of grain feeding. Among these, miR-10b expression was especially associated with feeding-induced changes and with the expression of the potential target genes responsible for glucose homeostasis and intramuscular fat depot in the LL muscle of JB cattle.

Reproductive performance of Japanese Black cattle: Association with herd size, season, and parity in commercial cow-calf operations

The Japanese Black is the most common breed of beef cattle in Japan. However, only limited data are available on the associations of season, parity, and herd size with reproductive performance in Japanese Black cattle. Therefore, the objective of the present study was to determine the associations of these factors with reproductive performance parameters, such as the calving to first service interval (CFSI) and first service conception rate in Japanese Black cattle. Data were collected from 34,763 calvings in 13,186 animals from 826 commercial cow-calf operations in the Miyazaki prefecture, which is located on the south eastern coast of Kyushu, Japan. This region has a temperate climate with warm humid summers and cold winters. All cattle were reared intensively, and the animals were housed in free stalls throughout their lives. The mean number of cows per farm was 18 (range, 1–454). All animals were bred by artificial insemination. Herds were classified into three groups based on size: small (≤10 cows), intermediate (11–50 cows), and large (≥51 cows). The mean (±SD) parity, CFSI, and the first service conception rate were 4.9 ± 2.9, 80.0 ± 46.2 days, and 53.5 ± 49.9%, respectively. Cows that calved in the spring (March to May) and winter (December to February) had the longest CFSI (P < 0.05). The CFSI in first-parity cows was shorter than in cows at parity 7 or higher (P < 0.05). Cows in large herds had an approximately 10 days shorter mean CFSI than those in small herds (P < 0.05). Cows inseminated in the winter or spring had an approximately 5% points lesser first-service conception rate (FSCR) than those inseminated during the summer (June to August) or autumn (September to November; P < 0.05). As parity increased from 1 to 9, FSCR decreased from 60.0% to 43.1% (P < 0.05). Cows in small herds had a lesser FSCR than those in intermediate and large herds (P < 0.05). In summary, decreased reproductive performance in intensively reared Japanese Black cattle was associated with calving and artificial insemination during the winter and spring, greater parity, and small herd size.

Fetal gender prediction based on maternal plasma testosterone and insulin-like peptide 3 concentrations at midgestation and late gestation in cattle

We compared maternal plasma testosterone and insulin-like peptide 3 (INSL3) concentrations between dams carrying a male versus female fetus from early to late gestation and examined the application of maternal hormonal concentrations to fetal gender prediction in dairy and beef cattle. Blood samples were collected from Holstein cows or heifers (N = 31) and Japanese Black beef cows (N = 33) at 1-month intervals at 2 to 8 months of gestation. Fetal gender was confirmed by visual observation of external genitalia of calves just after birth. Plasma testosterone and INSL3 concentrations were determined by enzyme-immunoassay. Fetal genders were judged based on cutoff values of maternal testosterone and INSL3 concentrations (male, if it was ≥ cutoff value; female, if < cutoff value), which we set for each hormone at each gestational month using receiver operating characteristic curves. Plasma testosterone concentrations were higher for dams with a male fetus than those with a female at 4, 5, 7, and 8 months for the dairy cattle (P < 0.05) and at 4, 5, 6, and 8 months for the beef cows (P < 0.05). Plasma INSL3 concentrations were higher for dams with a male fetus than those with a female at 2 and 6 months for the dairy cattle (P < 0.05) and at 4 to 8 months for the beef cows (P < 0.05). The predictive values and detection rates for fetal gender prediction based on maternal testosterone concentrations were 75.8% to 79.3% for dairy cattle at 5 and 7 months and for beef cows at 5 and 6 months, whereas those values by maternal INSL3 concentrations were 71.0% to 72.4% for the dairy cattle at 6 months and beef cows at 4 and 8 months. When multiple time points of testosterone and INSL3 concentrations at several midgestation and late gestation months were considered for fetal gender prediction, predictive values were 89.3% (5–7 months) and 85.7% to 88.0% (4–6, 8 months) for the dairy and beef breeds, respectively. Maternal testosterone and INSL3 concentrations in dams carrying a male fetus were higher than those carrying a female at midgestation and/or late gestation in Holstein and Japanese Black beef cattle. Nearly, 80% accuracy was obtained for fetal gender prediction by a single time point of maternal plasma testosterone concentrations at midgestation. Nearly 90% accuracy for the prediction was obtained when multiple time points of testosterone and INSL3 concentrations from midgestation to late gestation were considered.

Effects of parity and season on pregnancy rates after the transfer of embryos to repeat-breeder Japanese Black beef cattle

Abstract. Repeat-breeder (RB) cows are a major source of economic waste due to their decreased fertility. Embryo transfer (ET) is an alternative tool to improve the fertility of RB cows. The aims of the present study were to evaluate the effects of recipient parity and the season on pregnancy rates following ET in RB Japanese Black beef cattle. Embryos were transferred nonsurgically to recipients, consisting of 155 heifers (&lt; 2 years old) and 172 cows (&lt; 8 years old), which were defined as RB cattle. Of the recipients that were presented for ET, 57 recipients received a fresh embryo and 270 recipients received a frozen embryo. There were no differences in the pregnancy rates between cattle that received fresh embryos or frozen embryos. The rates of recipients with pregnancy, abortion, stillbirth, and normal calving were similar between heifers and cows. In cows, the pregnancy rates were lower (P &lt; 0.05) in summer (June to August) than in spring (March to May) and winter (December to February). In heifers, however, there were no differences in the pregnancy rates among the seasons. Our findings indicate that in RB Japanese Black beef cattle, the parity of the recipients does not have an effect on the pregnancy rates following the transfer of fresh and frozen embryos. However, heat stress may affect reproductive performance in RB Japanese Black cows.

Genetic Polymorphisms of Cytochrome P450 2D14 (CYP2D14) Gene in Japanese Black Cattle and Holstein-Friesian Cattle

Two types of cytochrome P450 2D14 (CYP2D14) gene deletions (GD1 and GD2) in Japanese Black cattle has been reported by us. In this study, we determined the frequency of cytochrome P450 2D14 (CYP2D14) genetic polymorphisms in 48 Japanese Black (JB) and 48 Holstein-Friesian (HF) cattle using polymerase chain reaction (PCR)-direct sequencing. Two types of CYP2D14 gene deletion variants, GD1 and GD2, were observed 58% in JB cattle, but only 8% of HF cattle. Genotype frequencies of CYP2D14 gene (105 C>A) also were assessed, but the AA substitution was not detected. The results of CYP2D14 gene variation study in cattle show that CYP2D14 GD allele may be an important mutation relevant to an enzyme defect in JB cattle because of high frequency of gene deletion variants.