Calf production from vitrified bovine sexed embryos following in‐straw dilution

The objective of this study was to develop an in‐straw dilution method suitable for direct transfer of vitrified bovine sexed embryos. Embryo sexing was performed by molecular diagnosis. Several sexed and vitrified‐warmed embryos were transferred after evaluation of morphologically embryonic survival at warming and in‐straw dilution (Evaluation group). The other embryos were immediately directly transferred to recipients without first being expelled from the straws after in‐straw dilution (Non‐evaluation group). The pregnancy rates of vitrified sexed embryos were 38.7% and 34.8% in the Evaluation group and Non‐evaluation group, respectively, which were not significantly different. The viability of lower quality embryos before vitrification tended to be lower (P = 0.087) than that of the higher quality embryos regardless of evaluating embryos after warming and in‐straw dilution. The abortion rates were similar, and there was no difference between the two groups (13.9% and 12.5%, respectively). These results demonstrate that vitrified bovine sexed embryos can be vitrified and diluted by the in‐straw method and that the vitrified and warmed sexed embryos can develop to term.     

The value of sexed bovine semen

Semen sexing may be used in a variety of practical situations, where part (or all) of the herd may be inseminated with X‐ and Y‐chromosome‐enriched semen. Expressions are presented to calculate the net present value of progeny derived from a semen dose, dependent on the values of females and males, and on the efficiency of sexing. Sexed semen allows selling a higher proportion of the more valuable sex and also increases the value of animals retained for breeding through more intense selection. The expressions to economically evaluate sexed semen are quite general but numerical examples are presented for several practical situations of interest in Brazil.     

Production of sexed calves from frozen-thawed embryos

Three experiments have been conducted with the aim of producing calves from frozen, sexed embryos by combining embryo splitting and cytogenetic methods. In the first experiment, the efficacy of the bisection technique was assessed by transcervical transfer of 10 monozygotic pairs of half embryos to 10 synchronised heifers. Thirteen calves were produced, including four sets of identical twins. In the second experiment, one of the halves of each of eight split embryos was transferred while the other was processed for sexing by identification of the sex chromosomes. In the third experiment, one of the halves from each of 28 embryos was frozen while the other half was used for sexing. Eleven of the 16 which were sexed have been transferred with the production of three calves of the predicted sex. The overall sexing rate was 60 per cent and the calving rate following transfer of sexed embryos was 60 per cent and 23 per cent for fresh and frozen halves respectively.     

Validating bovine sexed semen samples using quantitative PCR

In cattle, separation of X‐ and Y‐bearing sperm cells by flow‐sorting technology makes it possible to predetermine the sex of calves. Due to high costs and decrease in fertilization, the extensive use of sexed semen in livestock depends heavily on sorting purity of sperm cells. Validating the accuracy of sperm sexing requires reliable procedures, therefore a real‐time polymerase chain reaction (PCR) assay was established to calculate the male cell proportion in the sexed semen based on the relationship between the amplification of a SRY fragment and an autosomal gene (MSHR) fragment. Our results showed stable amplification of SRY for 100–1 ng of genomic DNA, which allows detection of 1% of male cells if 100 ng of target DNA is used. To account for the discrepancy in the efficiency of the MSHR and the SRY amplification correction of the difference of the mean values was performed. The ratio of male to female sperm cells in unsexed semen cells was very accurately determined. The fractions of the sexed samples, however, were different from the expected range appearing lower than estimated. Thus, the study reveals that real‐time PCR provides a good basis for the examination of sexed sperm cells, but needs to be optimized for the samples.     

Economic effects of using sexed semen in Japanese dairy herds

Dairy farm agricultural income should increase when sexed semen is used instead of unsexed semen. This study simulated three scenarios: using unsexed semen (N), using X sperm of Holstein and unsexed semen of Japanese Black (H), and using X sperm of Holstein and Y sperm of Japanese Black (HJ). Two management scenarios were considered: conventional management (CONV); and the use of Japanese Black semen with surplus cows to produce F₁s where sufficient replacement female Holstein calves were obtained for maintenance (MAINT). In CONV, the agricultural incomes of H and HJ were 610 000–2 400 000 yen higher than that of N. The agricultural income increased when the difference in the prices between Holstein males and average F₁ male/female calves was 34 000–50 000 yen, that between Holstein male and female calves was 80 000–110 000 yen, and that between F₁ male and female calves was 50 000–90 000 yen. Therefore, the agricultural income can be increased by using sexed semen to select calves of a more valued breed and sex.     

水牛性控冷冻精液授精效果的研究

为优化推广水牛性控冷冻精液人工授精技术,本研究分析了不同类型、胎次、年龄的受体母牛及不输精员对水牛性控冷冻精液人工授精产犊率的影响。收集武鸣县8个村级牛人工授精点3 029头受体母水牛X性控冷冻精液人工授精产犊数据,利用卡方检验方法对所收集数据进行统计分析。结果表明:本研究3 029头受体母牛经人工授精后产犊率为44.2%(1340/3029),产母犊率为82.3%(1103/1340)。以本地水牛及杂交水牛作为受体母牛,杂交水牛人工授精产犊率极显著高于本地沼泽型水牛(P0.01)。不同年龄受体母牛人工授精产犊率差异不显著(P0.05),但存在组间差异。不同胎次受体牛人工授精产犊率差异不显著(P0.05),但存在组间差异。不同输精员人工授精产犊率差异极显著(P0.01)。本研究结果表明不同类型、年龄、胎次的受体母牛及输精员皆会影响到水牛性控冷冻精液人工授精效果。进一步加强受体母牛选择、加强输精员培训是今后水牛性控冷冻精液人工授精大范围推广应用不可忽视的环节。     

Production of sexed lambs after biopsy of ovine blastocyts produced in vitro

Embryos were generated by in vitro fertilization of in vitro-matured oocytes, cultured to the blastocyst stage, biopsied for sex determination by a PCR-based procedure, and transferred to synchronized recipients. Three out of 5 sheep (60%) were diagnosed pregnant, and 4 lambs of predicted sex were born.     

奶牛性控冻精人工授精影响因素研究

用分离X和Y精子的性控精液进行人工授精是控制家畜性别之最简单可行的方法.然而,低密度性控精液输精效果还不如常规人工授精,许多技术环节都有待改进.以常规冻精和稀释常规冻精为对照,研究解冻方法、输精时间和部位、不同精液来源和输精员以及育成和经产牛等因素对性控冻精人工授精妊娠率的影响.结果显示,精液解冻水浴温度和持续时间对人工授精效果有显著影响,性控精液对解冻水浴温度更敏感;性控冻精和稀释常规冻精比常规冻精对输精时间要求更严格;3种精液输精到排卵卵泡同侧子宫角基部受胎率都显著高于输精于子宫体和同侧子宫角前端;3种精液育成牛受胎率(80%)都显著高于经产牛(50%);于输精同时注射促排卵素3号明显提高性控冻精受胎率;经严格挑选、能够从事胚胎移植操作的技术熟练输精员之间性控冻精受胎率差异不显著;在所设计的不同条件下,性控冻精与稀释同样倍数的常规冻精行为相似,说明精子分离过程没有对精子造成特殊损伤.研究结果说明,精确控制人工授精各个技术环节可以实现消除性控与非性控、低密度与高密度精演之间的差别,获得高妊娠率.     

Characteristics of calves produced with sperm sexed by flow cytometry/cell sorting

The objectives of this study were to determine whether calves produced by sexed sperm differed from controls and to what extent the sex ratio of calves was altered by the sexing procedure. Data were collected from 1,169 calves produced from sperm sexed by flow cytometry/cell sorting after staining with Hoechst 33342, and 793 calves produced from control sperm during breeding trials between 1997 and 2001. Least squares ANOVA were completed using factors of treatment (sexed vs. control sperm), 19 management groups from 13 field trials, and calf sex. Responses analyzed include gestation length, birth weight, calving ease, calf vigor, weaning weight, abortion rate, and death rates (neonatal and through weaning). No significant difference was observed for any response due to treatment or treatment interactions (P > 0.10). Therefore, calves produced from sexed sperm grew and developed normally both pre- and postnatally. A neurological disorder was observed in four control calves and one sexed calf from one farm. No gross anatomical abnormalities were reported for any calves in the study. Differences were observed for all responses among management groups (P < 0.03 for abortions and P < 0.01 for all other responses). Heifer and bull calves differed (P < 0.001) in gestation length (278.4 and 279.6 d), birth weight (32.8 and 35.2 kg), calving ease (1.15 and 1.30), and weaning weight (233 and 247 kg). Gestation length did not affect characteristics of calves. The sex ratio at birth of calves from unsexed control sperm was 49.2% male. Sexing accuracy of X-sorted sperm was 87.8% female calves, and Y-sorted sperm produced 92.1% male calves. Flow cytometry/cell sorting can be used to preselect sex of calves safely with approximately 90% accuracy.     

Genetic gain in dairy cattle populations is increased using sexed semen in commercial herds

Using stochastic simulation, the effect of using sexed semen to cow dams (CD) in a dairy cattle breeding scheme, with or without use of multiple ovulation and embryo transfer (MOET) to bull dams (BD), on annual genetic gain at the population level was examined. Three levels of sexed semen were combined with three levels of MOET: no sexed semen, sexed semen to the best CD and sexed semen to all heifers, combined with no MOET, MOET on all BD and MOET randomly on 20% of the BD. In total, nine scenarios were compared. The simulated population was monitored for 30 years and included 450 herds with 100 cows each. Each year 50 young bulls (YB), 10 active sires and 215 BD were selected on best linear unbiased prediction estimated breeding values by truncation selection across the simulated population, and the YB were tested within the population. Use of sexed semen alone gave a positive increase in the annual genetic gain of 2.1% when used on the best CD and 2.7% when used on all heifers, but only the latter was statistically significant. The increased annual genetic gain was caused by a larger contribution from the CD to the BD. Use of sexed semen together with MOET on BD increased the annual genetic gain by 1.8-2.5% compared with schemes without sexed semen and MOET on all BD. Performing MOET on all BD enables selection of offspring with high Mendelian deviations, which increase the annual genetic gain. Use of sexed semen decreased the genetic lag between the sires and the CD by 12-14% when used on the best CD and by 6% when used to all heifers. The decrease in the genetic lag is caused by the increased selection intensity of the cow dams.     

State‐of‐the‐Art‐Review: Immunomodulatory effects of opioids

Objective – To review the immunomodulatory effects of opioids. Data Sources – Original research publications and review articles using the PubMed search engine with the following keywords – opioids, morphine, immuomodulation, and immunosuppression. Veterinary and Human Data Synthesis – Opioids have been shown to modulate the immune system in animal models by affecting both the acquired and innate arms of the immune system. Natural killer cell activity, T‐cell proliferation, antibody production, phagocytic cell function, and cytokine production have all been shown to be affected by opioids. Many of these effects are reversed by opioid antagonists. Opioids have also been shown to induce sepsis in laboratory animals. Opioid administration alters immune parameters in healthy humans at analgesic doses and may increase the risk of infection in some patient populations. Conclusions – While opioids remain the most powerful and widely used analgesics available, their negative effects on the immune system are well established in the laboratory setting. Thoughtful consideration should be given to the use of certain opioids in critically ill patients, especially those with pre‐existing immunocompromise.     

Pharmacokinetics and bioavailability after intramuscular injection of the 5‐HT1A serotonin agonist R‐8‐hydroxy‐2‐(di‐n‐propylamino) tetralin (8‐OH‐DPAT) in domestic goats (Capra aegagrus hircus)

To determine the bioavailability and pharmacokinetic properties of the serotonin 5‐HT_1A receptor agonist R‐8‐OH‐DPAT in goats, and 0.1 mg kg^?1 R‐8‐OH‐DPAT hydrobromide was administered intramuscularly (i.m.) and intravenously (i.v.) to six goats in a two‐phase cross‐over design experiment. Venous blood samples were collected from the jugular vein 2, 5, 10, 15, 20, 30, 40 and 60 min following treatment and analysed by liquid chromatography tandem mass spectrometry. Bioavailability and pharmacokinetic parameters were determined by a one‐compartment analysis. Mean bioavailability of R‐8‐OH‐DPAT when injected i.m. was 66%. The mean volume of distribution in the central compartment was 1.47 L kg^?1. The mean plasma body clearance was 0.056 L kg^?1 min^?1. All goats injected i.v. and two of six goats injected i.m. showed signs of serotonin toxicity. In conclusion, R‐8‐OH‐DPAT is well absorbed following i.m. injection and the observed pharmacokinetics suggest that administration via dart is feasible. Administration of R‐8‐OH‐DPAT hydrobromide, at a dosage of 0.1 mg kg^?1, resulted in the observation of clinical signs of serotonin toxicity in the goats. It is suggested that dosages for the clinical use of the compound should be lower in order to achieve the desired clinical effect without causing serotonin toxicity.     

Orexin‐B‐like immunoreactivity in pituitary αMSH‐producing cells and median eminence GnRH‐containing fibres of the flat‐tailed house gecko

We examined the distribution of the orexin‐like peptides in the pituitary and median eminence of the flat‐tailed house gecko (Hemidactylus platyurus) using immunohistochemistry. Orexin‐B‐like, but not orexin‐A‐like, immunoreactivity was detected in the pituitary, specifically in the pars intermedia, and these cells corresponded to alpha‐melanocyte‐stimulating hormone (αMSH)‐producing cells. Orexin‐B and αMSH secreted from pars intermedia may modulate secretion of adenohypophyseal cells in the pars distalis. In the median eminence, orexin‐B‐immunoreactive puncta and fibres were observed, and these structures corresponded to gonadotropin‐releasing hormone (GnRH)‐immunoreactive puncta and fibres. Orexin‐B secreted from GnRH‐containing neurons in the hypothalamus may affect thyrotropin‐releasing hormone‐containing neurons resulting in modulation of αMSH secretion of melanotrophs in the pars intermedia.