Monitoring changes in back fat thickness and its effect on the restoration of ovarian activity and fertility in Bos indicus cows

With the objective of testing the hypothesis if animals with a stable layer of body fat (FAT) during the peripartum have a better chance of becoming pregnant after calving, fifty‐nine multiparous Brahman cows in their last trimester of pregnancy were used. Animals averaged four parturitions and were stocked at a rate of 1.25 animal units per hectare and divided into two groups depending on the time postpartum (dpp) that the intravaginal releasing device CIDR was inserted; Group 1 (<30 dpp; n = 30) received the implant at 25.2 ± 4.21 and withdrawn 9 days later. Group 2 (≥30 dpp; n = 29) received the CIDR at 38.41 ± 5.8. Animals were AI at detected oestrus until 170 dpp and calculated as pregnant at first service or requiring more than one service (1s and >1s), not pregnant but cycling (not pregnant) and those not cycling at all (anestrus). The FAT measurements were taken twice each month from the last trimester of gestation until 96 dpp. The onset of ovarian activity was monitored through blood levels of progesterone (P4) at days 14 and 9 prior to CIDR insertion and days 10, 13, 30 and 33 after CIDR withdrawal. Animals pregnant did not have any major changes in their fat thickness. In contrast, cows pregnant in the group ≥30 dpp had changes in their FAT homoeostasis, and pregnant animals in the 1s and >1s groups did not show differences in dorsal back fat in the last trimester of pregnancy and early postpartum. In contrast, animals not pregnant and in anestrus FAT values decreased considerably after parturition. Overall, fertility was 49%, but 18% of all the animals remained anestrus losing FAT. Thus, animals with adequate metabolic conditions will have a better chance of pregnancy regardless of the time postpartum when the reproductive programme starts.     

The effect of select seminal plasma proteins on endometrial mRNA cytokine expression in mares susceptible to persistent mating‐induced endometritis

In the horse, breeding induces a transient endometrial inflammation. A subset of mares are unable to resolve this inflammation, and they are considered susceptible to persistent mating‐induced endometritis PMIE Select seminal plasma proteins cysteine‐rich secretory protein‐3 (CRISP‐3) and lactoferrin have been shown to affect the innate immune response to sperm in vitro. The objective of this study was to determine whether the addition of CRISP‐3 and lactoferrin at the time of insemination had an effect on the mRNA expression of endometrial cytokines in susceptible mares after breeding. Six mares classified as susceptible to PMIE were inseminated during four consecutive oestrous cycles with treatments in randomized order of: 1 mg/ml CRISP‐3, 150 μg/ml lactoferrin, seminal plasma (positive control) or lactated Ringer's solution (LRS; negative control) to a total volume of 10 ml combined with 1 × 10⁹ spermatozoa pooled from two stallions. Six hours after treatment, an endometrial biopsy was obtained for qPCR analysis of selected genes associated with inflammation (pro‐inflammatory cytokines interleukin (IL)‐1β, IL‐8, tumour necrosis factor (TNF)‐α, interferon (INF)‐γ, anti‐inflammatory cytokines IL‐1RN and IL‐10, and inflammatory‐modulating cytokine IL‐6). Seminal plasma treatment increased the mRNA expression of IL‐1β (p = .019) and IL‐8 (p = .0068), while suppressing the mRNA expression of TNF (p = .0013). Lactoferrin also suppressed the mRNA expression of TNF (p = .0013). In conclusion, exogenous lactoferrin may be considered as one modulator of the complex series of events resulting in the poorly regulated pro‐inflammatory response seen in susceptible mares.     

Supplementing rumen‐protected methionine to lactating multiparous dairy cows did not improve reproductive performance

There is evidence that supplementing methionine has positive effects on uterine environment, oocyte quality and embryo development in cattle. Thus, the objective of this study was to evaluate reproductive traits of cows supplemented with rumen‐protected methionine (RPM) during early to mid‐lactation in comparison with an untreated control group (CON). An additional focus was on the effect of puerperal diseases on reproductive performance parameters in RPM‐supplemented group MET and in CON. A total of 1,709 multiparous Holstein‐Friesian cows were enrolled in this field trial conducted on a commercial dairy farm in Slovakia. Cows were allocated at approximately 12 days post‐partum (dpp) to either CON or MET, the latter supplemented with 25.0 g–27.2 g RPM per cow per day incorporated into the total mixed ration (TMR) until leaving the study pen at approximately 140 dpp. The amount of RPM was calculated based on individual feed ingredients analysis and adjusted during the study period when TMR changed. Cows were monitored during the post‐partum period by vaginal examination (day 5 pp), measuring of beta‐hydroxybutyrate in blood (3, 5, and 8 dpp) and by vaginal examination, uterine cytology and measuring of back fat thickness by ultrasound (all at 31 ± 3 dpp). Compared with CON, cows supplemented with RPM did not show better reproduction performance parameters (first service submission rate, days to first service, conception risk, days open 140). Results from binary logistic regression model for the risk of conception showed that metritis had a significant effect, but the supplementation of methionine had not. Results of Cox regression analysis for the odds of conception within 140 dpp revealed only metritis and clinical endometritis as significant factors. In conclusion, supplementation of RPM had no beneficial effect on reproductive performance in this study farm compared with an untreated control group.     

Use of postpartum vaginoscopic (visual vaginal) examination of dairy cows for the diagnosis of endometritis and the association of endrometritis with reduced reproductive performance

OBJECTIVE: To assess the association between the findings from vaginoscopic examination of postpartum dairy cows with peripartum reproductive disease and their subsequent reproductive performance, and to determine the factors that might be associated with a positive vaginoscopic examination (VV). METHODS: Cows (n=1325) from 17 seasonal calving dairy herds were enrolled if they had been calved at least 7 days and had at least one of the following conditions that placed them at risk of endometritis: retained fetal membranes (RFM), dystocia, a dead calf, hypocalcaemia, twin birth, calving induction or an observed vulval discharge (VD). Examination was undertaken 28-37 days before mating start date (MSD) within each herd. All cows were body condition scored (BCS) and were VV scored on a scale of 0 (clear) to 3 (purulent). The uterus and ovaries were assessed by rectal palpation. RESULTS: Cows with a positive VV score (1-3) were less likely to conceive to first service and had a lower pregnancy proportion than cows that had a negative VV score (score 0). Mean MSD to conception interval was longer in VV-positive cows. A positive VV score was associated with a low BCS, primiparity, intrapelvic uterus, poor uterine tone, large uterus, RFM, VD, dystocia, dead calf and twins. CONCLUSION: In the present study a positive VV score was associated with reduced reproductive performance and was more common in primiparous and low BCS cows. Of the at-risk cows, those with RFM, VD, dystocia, dead calf or twins were more likely to have a positive VV score.     

Comparison of two methods of detecting purulent vaginal discharge in postpartum dairy cows and effect of intrauterine cephapirin on reproductive performance

Objective   Part 1: compare the use of a Metricheck™ device (a stainless steel probe with a semi-spherical rubber cup attached at one end) to sample the contents of the anterior vagina with a vaginal speculum examination for the diagnosis of pus in the vagina of postpartum dairy cows and to investigate the association of that pus with reproductive performance. Part 2: assess the effect of a single intrauterine infusion of 500 mg cephapirin in cows diagnosed with vaginal purulent or mucopurulent discharge 7 to 28 days after calving on reproductive performance.
Procedure   Six herds were visited fortnightly to examine cows that had calved between 7 and 28 days (n = 423) with both the Metricheck device and a vaginal speculum to score, by each method, the vaginal discharge from 0 (clear or absent) to 3 (purulent) for each animal included in the study. Half of the cows that had a positive discharge score (1 to 3 by either examination method) were then treated with an intrauterine infusion of 500 mg of cephapirin. The relationship between Metricheck score, vaginoscopy score, treatment and reproductive performance was assessed.
Results   There was a substantial measure of agreement between each method when scores were analysed by status. Cows that were positive with either method had inferior reproductive performance compared with cows with a score of zero. Treatment of cows diagnosed with a purulent or mucopurulent discharge with intrauterine cephapirin improved reproductive performance in both the vaginoscopy and Metricheck groups.     

Genome‐wide linkage disequilibrium in the Blonde d'Aquitaine cattle breed

We present here the first genome‐wide characterization of linkage disequilibrium (LD) in the French Blonde d'Aquitaine (BLA) breed, a well‐muscled breed renowned for producing high‐yielding beef carcasses. To assess the pattern and extent of LD, we used a sample of 30 unrelated bulls and 36 923 single nucleotide polymorphisms (SNPs) covering all cattle autosomes. The squared correlation of the alleles at two loci (r²) was used as a measure of LD. The analysis of adjacent marker pairs revealed that the level of LD decreases rapidly with physical distance between SNPs. Overall mean r² was 0.205 (±0.262). Strong LD (r² > 0.8) and useful LD (measured as r² > 0.2) were observed within genomic regions of up to 720 and 724 kb, respectively. We analysed the genetic structure of the BLA population and found stratification. The observed genetic sub‐structuring is consistent with the known recent demographic history that occurred during BLA breed formation. Our results indicate that LD mapping of phenotypic traits in the BLA population is feasible; however, because of this sub‐structuring, special care is needed to reduce the likelihood of false‐positive associations between marker loci and traits of interest.     

2018年国内外家兔遗传育种及繁殖研究进展

该文主要针对2018年国内外家兔传统育种、分子育种和繁殖技术3个方面的研究进展展开综述,其中传统育种方面主要研究了选择效应及性状评定、遗传与环境互作和种质性能测定;分子育种方面主要涉及生长、肉质、皮毛、繁殖等性状相关基因的研究;而家兔繁殖技术方面主要包括精液冷冻研究及添加物和环境对家兔繁殖的影响。2018年国内在家兔传统育种和分子育种方面研究较多,传统育种主要对一些地方品种种质性能进行了测定和比较;分子育种主要集中于肉质、皮毛和繁殖性状的研究,并获得了新的相关分子标记和基因;但家兔繁殖技术方面研究相对较少。而国外传统育种主要研究了选择与性状评定和遗传与环境互作;分子育种主要集中在筛选生长与肉质及繁殖性状分子标记的研究方面,但在皮毛性状方面的研究相对欠缺,且国外分子育种主要是使用传统的研究方法筛选分子标记或研究性状相关基因的功能,而国内多采用高通量测序技术筛选对研究性状具有重要调控功能的基因及调控网络。作者对2018年国内外家兔育种研究进行了综述,以期为今后家兔育种提供参考。     

Genome‐wide analysis of homozygosity regions in european simmental bulls

The study of Runs of Homozygosity (ROH) is a useful approach for the characterization of the genome of livestock populations. Due to their high relationship with autozygosity, ROH allow to make inference about population genetic history, to estimate the level of inbreeding, to assess within breed heterogeneity and to detect the footprints of selection on livestock genomes. Aim of this study was to investigate the distribution of runs of homozygosity in bulls belonging to five European Simmental populations and to assess the relationship between three production traits (milk yield, fat and protein contents) and autozygosity. ROH count, distribution and ROH‐based coefficient of inbreeding (F_ROH) were calculated for 3,845 Simmental bulls of five different European countries: Austria (AT), Switzerland (CH), Czech Republic (CZ), Germany (DE) and Italy (IT). Average values of ROH number per animal, and total genome length covered by ROH were 77.8 ± 20.7 and 205 ± 74.4 Mb, respectively. Bulls from AT, DE and IT exhibited similar ROH characteristics. Swiss animals showed the highest (12.6%), while CZ the lowest (4.6%) F_ROH coefficient. The relationship between ROH occurrence and milk production traits was investigated through a genome‐wide ROH‐traits association analysis (GWRA). A total of 34 regions previously associated with milk traits (yield and/or composition) were identified by GWRA. Results of the present research highlight a mixed genetic background in the 5 European Simmental populations, with the possible presence of three subgroups. Moreover, a strong relationship between autozygosity and production traits has been detected.     

Effect of intrauterine treatment with cephapirin on the reproductive performance of seasonally calving dairy cows at risk of endometritis following periparturient disease

OBJECTIVE: To determine the effect of intrauterine cephapirin (0.5 g) treatment on the reproductive performance of cows diagnosed as at risk of developing endometritis. METHODS: Cows (n = 1325) from 17 seasonal calving dairy herds were enrolled if they had been calved for more than 6 days and had a condition that placed them at risk of endometritis. Half were treated with intrauterine cephapirin at an examination performed 28-37 days prior to mating start date (MSD). Cows were scored for body condition, their vaginal discharge was scored using vaginoscopy (VV), and the uterus and ovaries were assessed by rectal palpation. RESULTS: Overall, there was no significant treatment effect on reproductive performance. In 945 modified at risk (MAR) cows the effect of treatment varied with the calving to treatment interval (CTI) and VV status. For the subset of 229 MAR cows with CTI < or = 28 days, treatment improved the proportions of first-service conception (OR 3.1; P < 0.01) and 6-week in-calf (OR 2.1; P < 0.05), and reduced the mean MSD to conception interval by 20 days (P < 0.05). The difference was greater in cows with a positive VV score (1-3). Treated VV-negative cows with CTI > 48 days had a reduced proportion of cows in-calf by 6 weeks (OR 0.58; P = 0.056) compared with untreated cows. CONCLUSION: Intrauterine cephapirin infusion of MAR cows improved reproductive performance, depending on CTI. The greater treatment effect in VV-positive cows suggests that VV scoring is a useful tool for the diagnosis of endometritis.     

Evaluation of animal models to explore the influence of maternal genetic and maternal permanent environment effect on reproductive performance of Jersey crossbred cattle

The present study was conducted on 1,002 reproductive records of 430 Jersey crossbred cattle, descended from 57 sires and 198 dams, maintained at the Eastern Regional Station of ICAR-National Dairy Research Institute, Kalyani, Nadia, West Bengal, India to investigate the influence of direct genetic, maternal genetic and maternal permanent environmental effect on three most important reproductive traits viz., number of service per conception (NSPC), days open (DO) and calving interval (CI) of Jersey crossbred cattle. Six single-trait animal models (including or excluding maternal genetic or permanent environmental effects) were fitted to analyse these traits, and the best model was chosen after testing the significant increase in the log-likelihood values when additional parameters were added in the model. Direct heritability estimates for NSPC, DO and CI from the best model were 0.10, 0.14 and 0.20, respectively. The maternal permanent environmental (c²) effects on reproductive traits accounted for almost negligible fraction of the total phenotypic variance in this study. The maternal genetic effects (m²) also contributed very little (0%–3%) to the total phenotypic variance except for CI where it was important and accounted for 20% of phenotypic variance. A significantly large negative genetic correlation was observed between direct and maternal genetic effects for all traits, suggesting the presence of antagonistic relationship between dam's direct additive component and daughter's additive genetic component. Results suggest that both direct and maternal effects were important only for CI but not for other traits. Therefore, both direct additive effects and maternal genetic effect need to be considered for improving this trait by selection.     

我国牛遗传育种研究进展

过去二十多年的牛育种工作取得了长足进展,同时也面临良师益友上飞速发展的生物技术的严重挑战。本文将从常规育种方法的评价、数量遗传学在牛育种中的应用、计算机技术与牛的育种、遗传标记及其在牛育种中的应用、生物技术与牛的育种五个方面详细综述牛的育种进、遗传主其在牛育种中的应用、生物技术与牛的育种五个方面详细综述牛的育种进展,为我国养牛产业化发展提供依据。     

mtDNA在家畜遗传育种中的应用

家畜ｍｔＤＮＡ具有大小恒定、核苷酸替代率多，以母性方式遗传、密码不通用性、基因排列相当经济、同源性高等基本特点，其多态性很丰富，可用于基因工程，家畜品种起源进化、亲缘关系、畜群遗传结构、及其与家畜生产性能的关系等方面的研究，这将为ｍｔＤＮＡ广泛应用于家畜遗传能种领域提供重要的理论价值和实际意义。     

Association of herd BRSV and BHV-1 seroprevalence with respiratory disease and reproductive performance in adult dairy cattle

Background

The aim of this study was to detect the associations between bovine herpesvirus 1 (BHV-1) status of a herd and respiratory disease (BRD) occurrence and reproductive performance in pregnant heifers and cows. The association between management-related factors and higher BRD occurrence was also estimated.

Methods

Serum samples, collected from cows and youngstock from 103 dairy cattle herds, were analyzed for antibodies against BHV-1, bovine respiratory syncytial virus (BRSV), bovine viral diarrhoea virus (BVDV), and Mycoplasma bovis. A questionnaire was used to collect data concerning herd management factors and reproductive performance, as well as the occurrence of clinical signs of respiratory disease in the last two years, as evaluated by the veterinarian or farm manager. Multiple correspondence analysis (MCA) and logistic regression analysis were performed to identify and quantify the risk factors.

Results

A low to moderate prevalence (1-49%) of BRSV antibodies among youngstock was associated with a high occurrence of respiratory disease (OR = 6.2, p = 0.010) in cows and in-calf heifers. Employees of the farm may participate in the spread of such disease. Larger herd size, loose-housing of cows, housing youngstock separately from cows until pregnancy, and purchasing new animals were factors possibly related to a high occurrence of respiratory disease symptoms in pregnant heifers and cows. The highest risk of abortions (> 1.3%) and increased insemination index (number of inseminations per pregnancy) (> 1.9) occurred in herds with a moderate prevalence of BHV-1 antibodies (1-49%) in cows.

Conclusions

BHV-1 was not associated with acute respiratory disease in adult dairy cattle, however was significantly related to reproductive performance. BRSV possesses the main role in respiratory disease complex in adult dairy cattle.     

线粒体DNA在牛遗传育种中的应用

线粒体DNA是动物体内除了核DNA之外的唯一遗传物质,它具有结构简单、进化速度快、母系遗传和基因重组率小等特点被广泛应用于研究。本文在介绍线粒体DNA的特点和研究现状的基础上,对线粒体DNA在牛的起源进化、亲缘关系、杂交育种和生产性能等方面的应用进行了阐述。     

Breeding objectives for the Boran breed in Kenya: Model development and application to pasture-based production systems

Bio‐economic profit models were developed and applied to evaluate biological and economic variables that characterize production systems utilizing the Boran breed. Production systems were described according to their sale age (24 months short‐fed or 36 months long‐fed), levels of input (low, medium or high) and final goal (beef or dual purpose) representing practical circumstances that exist in the various beef cattle farms in Kenya. The input variables were classified into production and economic variables. The outputs from the profit models included revenue, costs and feed intake of cows, heifers and steers in the different production systems. These models can be used to simulate changes in production and marketing circumstances. The biological relationships and assumptions in the model are general and flexible and can therefore be applied to a wide range of beef cattle production circumstances by changing the input variables. In addition, by modifying the herd dynamics and management variables this model may be applied in Kenya or other countries to production systems that utilize indigenous cattle genetic resources or their crosses with Bos taurus breeds.     

2017年国内外家兔遗传育种研究进展

作者对2017年国内外家兔遗传育种（传统育种、分子育种、繁殖技术）相关的研究进展进行了综述,发现国内外研究侧重不同,且与往年相比存在明显变化。国内传统育种主要包括品种选育和性状评定两方面研究,并取得了良好的进展;在分子育种领域做了较多的研究,主要涉及性状包括生长、肉质、皮毛、繁殖、抗病性能等,并筛选了与目标性状相关联的功能性基因和分子标记;繁殖技术研究少而散,包括人工授精、配种季节和光控管理等环境效应对家兔健康和生产力影响的研究。国外传统育种包括性状遗传评估、遗传与环境互作、评估方法等,在改进生长性能和肉质方面得到了提升;分子育种主要涉及生长、肉质、抗病及繁殖等性状,也进行了分子标记筛选与研究,但在皮毛性状方面研究相对欠缺;繁殖技术主要包括环境和添加物对家兔繁殖、精液冷冻等方面的影响研究,也取得了良好进展。本综述可为后期家兔育种研究和生产提供参考。     

Phenotypic and genetic variation in longevity of Polish Landrace sows

The influence of some production traits on the longevity of Polish Landrace sows was evaluated using survival analysis. Estimates of genetic parameters were obtained from the sire and animal components in linear and survival methodologies. Comparison between survival and linear models was based on heritabilities and ranking of estimated breeding values of sires. The same data set, 13 031 sows, was used for both methodologies, even in the presence of censored observations. The effects of herd*year and year*season of the first farrowing had the largest influence on the risk of culling of sows. Sows born in spring season (March–May) had a 24% (p < 0.001) lower hazard for removal than those born in winter (December–February). The age at first farrowing had a small but significant effect on culling: the hazard regression coefficient for this trait was 0.002 per day. Sows that had more piglets born alive and fewer stillborn in the first litter had a decreased risk of being culled. Within a contemporary group, slower growing gilts had decreased removal risk. The relative risk ratios show a marginal decreased rate of culling for sows with backfat thickness between 9.5 and 11 mm compared to the leaner sows. Loin depth had no effect on sow longevity. Heritability estimates ranged from 0.09 to 0.38 depending on the model and type of analysis. In survival analysis, all heritabilities for longevity were higher when analysed with sire models (0.21 and 0.38) compared to animal models (0.09 and 0.16). The use of animal or sire models in the linear analysis gave similar heritability estimates (0.12 and 0.10). Correlations between breeding values for sires were moderate and high, with absolute values from 0.51 to 0.99, depending on the model fitted and methodology. A stronger correlations within methodologies (0.83–0.99) than within models with different methodologies (0.51–0.63) were obtained.     

2019年国内外家兔遗传育种与繁殖研究进展

家兔是节粮型草食小动物,其养殖投资少、见效快,已成为中国促进农民增收、助力脱贫攻坚的优势产业。近年来,随着生命科学的发展,国内外家兔遗传育种取得了较大进展。文章分别从家兔传统育种、分子育种和繁殖等方面对国内外2019年家兔遗传育种与繁殖研究进展进行了综述。国外在传统育种、分子育种和家兔繁殖方面均作了较多的研究,传统育种主要是针对选择和环境及添加物对家兔生产性能影响的研究;分子育种方面主要是对繁殖性状相关基因的研究,其中产仔数及精液蛋白方面的研究较多,其次是生长、肉质、毛色等性状相关基因的研究;而繁殖方面的研究主要针对公兔精液的保存方法及添加物对家兔精液品质、产仔数和受胎率的影响。国内家兔遗传育种与繁殖研究也主要包括传统育种、分子育种和家兔繁殖,但国内的研究重点在分子育种研究,其中品种与遗传多样性及皮毛性状功能基因的研究较多,主要采用高通量测序、常规基因克隆和基因编辑的方法筛选对研究性状具有重要调控功能的基因及调控网络;而传统育种性状评定和家兔繁殖方面的研究相对较少。该综述可为家兔的育种和生产研究提供参考。