Identification of complex vertebral malformation carriers in Holstein cattle in south China

Complex vertebral malformation (CVM) is a recently described monogenic autosomal recessive hereditary defect of Holstein dairy cattle that causes premature birth, aborted fetuses and stillborn calves. Guanine is substituted by thymine (G>T) in the solute carrier family 35 member A3 gene (SLC35A3). A valine is changed to a phenylalanine at position 180 of uridine 5'-diphosphate-N-acetyl-glucosamine transporter protein. CVM is expected to occur in many countries due to the widespread use of sire semen. We developed a created restriction site PCR (CRS-PCR) method to diagnose CVM in dairy cows. This was tested on 217 cows and 125 bulls selected randomly from a Holstein cattle population in south China. Five Holstein cows and five Holstein bulls were identified to be CVM carriers; the percentages of CVM carriers were estimated to be 2.3, 4.0 and 2.9% in the cows, bulls and entire Holstein cattle sample, respectively.     

牛脊柱畸形综合征检测方法的建立与应用

牛脊柱畸形综合征(Complex vertebral malformation, CVM)是近年来新发现的致死性牛常染色体隐性遗传缺陷病。由于编码UDP-N-乙酰葡糖胺载体的SLC35A3基因发生G→T的突变而引起本病的发生, 可引起胎牛死胎、流产、早产。为了解我国正常的荷斯坦牛(黑白花奶牛)的CVM携带和发生情况, 建立、应用创造酶切位点PCR(Created restriction site PCR, CRS-PCR)、等位基因特异性PCR(Allele-specific polymerase chain reaction, AS-PCR)检测方法检测了表型正常的436头荷斯坦母牛和93头荷斯坦公牛, 检测到3头CVM携带者, 其中杂合母牛1头, 杂合公牛2头, 携带率分别为0.60%、2.20%。此方法简便、可靠, 为奶牛CVM有害基因的分型和筛选提供了新的方法和思路, 为我国奶牛的分子选育提供了可靠的理论依据。     

荷斯坦奶牛脊柱畸形综合征的研究进展

荷斯坦奶牛脊柱畸形综合征是近年新发现的一种常染色体隐性遗传病,该病对纯合子胎儿是致死性的。当荷斯坦牛的育种核心群中携带者达到一定比例,脊柱畸形综合征就会对奶业造成巨大损失。文章综述了脊柱畸形综合征的主要症状和影响、致病基因及检测方法的研究进展以及我国潜在的荷斯坦奶牛脊柱畸形综合征携带者的状况。     

Effects of sire and dam genotype for complex vertebral malformation (CVM) on risk of return-to-service in Holstein dairy cows and heifers

The emergence of a new hereditary disease, called "Complex vertebral malformation" (CVM), has been described in Holstein cattle population. This paper studied the incidence of mating concerning Holstein dairy cattle with CVM in Brittany and the possible influences of CVM status for sires and dams on return-to-service at different intervals post-service in cows and heifers. It was carried out based on a set of data for first and second inseminations between 1998 and 2001 in cows (n=530,538) and heifers (n=248,140). Incidence of matings between CVM gene carriers, between a carrier bull and a non-carrier cow and between a non-carrier bull and a carrier cow were estimated to be 1.4, 10.6 and 9%, respectively (1.1, 9.3 and 10.9%, respectively in heifers). Compared to CVM-free mating, the relative risk of return-to-service was increased when the sire was a CVM carrier and the dam was at risk of being a carrier, especially for late return (>25 days post-service). When the sire alone was a carrier, the relative risk was increased whenever the return occurred at a low but significant level. Following mating between a non-carrier bull and a dam at risk of being a carrier, the risk of return-to-service decreased at a low but significant level, whatever the interval in the heifers but only for 19-25 days intervals in the cows.     

Effects of Complex Vertebral Malformation on Fertility in Swedish Holstein Cattle

Complex vertebral malformation (CVM) is an autosomal recessive inherited defect in the Holstein breed. It causes intra-uterine mortality through the entire gestation period leading to repeat breeding and involuntary culling of cows and thereby economic losses. The defect was first reported in Denmark in 1999 and a direct DNA test for the defect has been available since February 2001. The aim of this study was to investigate if Holstein bulls heterozygous for the CVM gene had reduced reproductive performance, measured as non-return rate (NRR) and in a daughter fertility index. All genotyped Swedish Holstein bulls born between 1995 and 1999 were included. Altogether 228 bulls were analysed, of which 53 bulls, i.e. 23%, were confirmed CVM carriers. A statistically significant difference between carriers and non-carriers in the relative breeding value for NRR was observed for 168 days NRR (101.1 ± 0.9 vs. 103.1 ± 0.6, p < 0.05). There was no difference for 28 days NRR whereas the difference approached significance for 56 days NRR. No significant effect of the paternal CVM genotype on the daughter fertility index was shown probably due to the complexity of traits this index is composed of. In conclusion, the study showed that carriers of the CVM defect have an inferior NRR compared with non-carriers.     

Evaluation of the Inheritance of the Complex Vertebral Malformation Syndrome by Breeding Studies

To investigate the congenital complex vertebral malformation syndrome (CVM) in Holstein calves, two breeding studies were performed including 262 and 363 cows, respectively. Cows were selected from the Danish Cattle Database based on pedigree and insemination records. Selected cows were progeny of sires with an established heterozygous CVM genotype and pregnant after insemination with semen from another sire with heterozygous CVM genotype. Following calving the breeders should state, if the calf was normal and was requested to submit dead calves for necropsy. In both studies, significantly fewer CVM affected calves than expected were obtained; a finding probably reflecting extensive intrauterine mortality in CVM affected foetuses. The findings illustrate increased intrauterine mortality as a major potential bias in observational studies of inherited disorders.     

Induction of twinning in Holstein and Japanese black cows by ipsilateral frozen embryo transfer

Induction of twinning by ipsilateral nonsurgical transfer of two frozen-thawed Japanese Black bovine embryos to each of 20 Holstein and 26 Japanese Black cows, that had been kept under a stable in private farm conditions, was examined. The cows were monitored every 20 days from Day 25 to Day 65 of gestation for pregnancy and fetus survival (estrus is Day 0). Seventy-five per cent (15 of 20), 65.0% (13 of 20) or 60.0% (12 of 20) and 61.5% (16 of 26), 53.8% (14 of 26) or 50.0% (13 of 26) of Japanese Black cows were diagnosed pregnant at 25, 45 and 65 days after transfer by ultrasonic echography. Embryonic losses were observed between Days 25 and 65 in 29.2% (7) Holstein and 31.8% (7) Japanese Black cows. The twin pregnancy rate in Holstein and Japanese Black cows decreased with time; 60.0% (9 of 15) vs. 37.5% (6 of 16) at Day 25; 53.8% (7 of 13) vs. 28.6% (4 of 14) at Day 45 and 41.7% (5 of 12) vs. 15.4% (2 of 13) at Day 65. At calving, Holstein cows produced five sets of twins and seven single calves, and Japanese Black cows two sets of twins and 11 single calves. The twinning rate in Holstein cows was higher (P < 0.05) than that in Japanese Black cows, 41.7% (5 of 12) vs. 15.4% (2 of 13). The calf birth weight in Holsteins was heavier (P < 0.05) than that in Japanese Black dams (24.5 kg, 33.6 kg vs. 19.3 kg, 25.5 kg for twin and single calves). The placental weight in Holstein dams calving twins was heavier than that in Holstein dams calving a single calf or in Japanese Black dams calving either twins or a single calf (6.6 kg vs. 3.5 kg, 4.6 kg or 2.8 kg). The number of placentome in Holstein dams calving twins was also higher (P < 0.05) than that in Holstein dams calving a single calf or Japanese Black dams (103.5 vs. 41.8, 67.9, 33.0). The number of placentome was approximately double in dams calving twins than that of dams calving a single calf.     

Breed differences in growth hormone and insulin secretion between lactating Japanese Black cows (beef type) and Holstein cows (dairy type)

This study was performed to clarify the levels of growth hormone (GH) and insulin (INS) secretions and the glucose response to INS during lactation in a representative beef breed in Japan, Japanese Black cows, and to compare them with their counterparts in a dairy breed, Holstein cows. Six Japanese Black and seven Holstein primiparous cows received a single intravenous injection of GH-releasing factor (GRF; 0.25 microg/kg), glucose (112.5 mg/kg), or INS (0.2 U/kg) from late pregnancy (2 weeks antepartum) to mid-lactation (6 months postpartum). Japanese Black cows had one-tenth of the total milk yield of Holstein cows during lactation, and significantly lower GRF-induced GH and higher glucose-induced INS secretions than Holstein cows at all stages. In Japanese Black cows, even with lactation, these secretions remained essentially unchanged, whilst Holstein cows showed higher GH and lower INS secretions after the onset of lactation as compared with cows in late pregnancy. Both breeds had similar glucose response to INS at the respective stages. These results suggest that, during lactation, Japanese Black cows may minimize the catabolic effects of GH and sustain the anabolic effects of INS, in contrast with Holstein cows, but have similar ability to inhibit INS-mediated glucose utilization in peripheral tissues to Holstein cows.     

Prevalence of complex vertebral malformation carriers among Polish Holstein-Friesian bulls

An increasing number of Holstein calf births exhibiting vertebral deformations has been detected in Denmark since 1999 by a program monitoring the incidence of genetic diseases. Pedigree analysis demonstrated that the affected calves originated from a family afflicted by an autosomally recessively inherited complex vertebral malformation (CVM) syndrome. To determine the actual carrier frequency of the CVM-determining mutation in a population of Polish Holstein-Friesian (=Polish Black-and-White) cattle, we examined 202 proven bulls (active in 2001–2005) used by 4 domestic artificial insemination companies and 403 unproven bulls (under evaluation for breeding value). Out of the 605 bulls examined, 150 T/G heterozygotes were diagnosed, including 118 that were sons of known CVM carriers. Identification of a gene polymorphism in a bovine solute carrier family 35 member 3, termedSLC35A3, was conducted with the use of a new PCR-SSCP method (polymerase chain reaction - single stranded conformation polymorphism), which - due to its ease of use and high reliability - can be applied in widespread screening programs aimed at reducing the incidence of the CVM defect.     

Additional evidence of the formation of unbalanced embryos in cattle with the 7/21 Robertsonian translocation

To confirm the effect of the 7 21 Robertsonian translocation on fertility in Japanese Black Cattle, cytogenetic studies were performed on embryos collected from the following 3 mating groups: normal bull cross normal cow, translocation carrier bull cross normal cow, and normal bull cross translocation carrier cow. All the analyzable embryos showed normal chromosome complements when the parents had a normal karyotype. In the group sired by the 7 21 translocation heterozygous bulls, a total of 56 embryos had metaphases suitable for chromosome analyses. Out of these embryos, 28 had normal chromosome complements and 25 were embryos with a balanced karyotype. However, 3 (5.4%) were monosomic and trisomic embryos, presumably resulting from the fertilization of normal ova by aneuploid spermatozoa. Unbalanced embryos were also observed in the chromosome analyses of embryos derived from the 7 21 translocation heterozygous cows. These results suggest that the 7 21 translocation in the heterozygous state may be associated with a slight reduction in reproductive efficiency.     

Comparison of pure Holsteins to crossbred Holsteins with Norwegian Red cattle in first and second generations

A total of 1922 first generation crossbred cows born between 2005 and 2012 produced by inseminating purebred Israeli Holstein cows with Norwegian Red semen, and 7487 purebred Israeli Holstein cows of the same age in the same 50 herds were analyzed for production, calving traits, fertility, calving diseases, body condition score, abortion rate and survival under intensive commercial management conditions. Holstein cows were higher than crossbreds for 305-day milk, fat and protein production. Differences were 764, 1244, 1231 for kg milk; 23.4, 37.4, 35.6 for kg fat, and 16.7, 29.8, 29.8 for kg protein; for parities 1 through 3. Differences for fat concentration were not significant; while crossbred cows were higher for protein concentration by 0.06% to 0.08%. Differences for somatic cells counts were not significant. Milk production persistency was higher for Holstein cows by 5, 8.3 and 8% in parities 1 through 3. Crossbred cows were higher for conception status by 3.1, 3.6 and 4.7% in parities 1 through 3. Rates of metritis for Holsteins were higher than the crossbred cows by 7.8, 4.6 and 3.4% in parities 1 to 3. Differences for incidence of abortion, dystocia, ketosis and milk fever were not significant. Holstein cows were lower than crossbred cows for body condition score for all three parities, with differences of 0.2 to 0.4 units. Contrary to comparisons in other countries, herd-life was higher for Holsteins by 79 days. A total of 6321 Holstein cows born between 2007 and 2011 were higher than 765 progeny of crossbred cows backcrossed to Israeli Holsteins of the same ages for milk, fat and protein production. Differences were 279, 537, 542 kg milk; 10.5, 17.7, 17.0 kg fat and 6.2, 12.9, 13.2 kg protein for parities 1 through 3. Differences for fat concentration were not significant, while backcross cows were higher for protein percentage by 0.02% to 0.04%. The differences for somatic cell score, conception rate, and calving diseases other than metritis, were not significant. Holstein cows were lower than backcross cows by 1.5% to 2.5% for conception status in parities 1 to 3 and lower for body condition score for parities 1 and 2, with differences in the range of 0.06 to 0.09 units. Culling rates were higher, and herd-life lower for the crossbred cows. The gains obtained in secondary traits for crossbred cows did not compensate for the major reduction in production.     

Bovine mitochondrial DNA polymorphism in restriction endonuclease cleavage patterns and the location of the polymorphic sites

Cleavage patterns of mitochondrial DNA (mtDNA) by restriction endonuclease analysis were examined in four Japanese Black cows, three Japanese Shorthorn cows, and six Holstein cows. Seventeen restriction enzymes which recognize six base pairs and two restriction enzymes which recognize four base pairs were used in this study. Polymorphism was observed with three restriction enzymes, HindIII, TaqI, and MspI, and was detected within the breeds. Nucleotide substitution was determined in the HindIII polymorphic site by DNA cloning and sequencing; this is C----T at position 10126 of the URF-3 region. Furthermore, the MspI and TaqI polymorphic sites were located on the physical map.     

利用PCR-RFLP检测中国荷斯坦牛遗传缺陷——瓜氨酸血症

瓜氨酸血症(Citrullinemia)是荷斯坦牛尿素循环发生代谢紊乱的一种常染色体隐性遗传缺陷。精氨酸琥珀酸合成酶基因外显子5发生突变(C-T)对这一紊乱负责。本研究应用PCR-RFLP方法和DNA测序技术检测济南市周边120头荷斯坦母牛和山东奥克斯生物技术有限公司种公牛站50头荷斯坦公牛的精氨酸琥珀酸合成酶基因外显子5。结果发现,所检测的公牛未发现瓜氨酸血症突变基因携带者,母牛中有2头为携带者,携带频率为1.18%。     

Characterization of a donor mitochondrial DNA transmission bottleneck in nuclear transfer derived cow lineages

In embryos derived by nuclear-transfer (NT), fusion of donor cells with recipient oocytes resulted in varying patterns of mitochondrial DNA (mtDNA) transmission in NT animals. Distribution of donor cell mtDNA (D-mtDNA) found in offspring of NT-derived founders may also vary from donor cell and host embryo heteroplasmy to host embryo homoplasmy. Here we examined the transmission of mtDNA from NT cows to G(1) offspring. Eleven NT founder cows were produced by fusion of enucleated oocytes (Holstein/Japanese Black) with Jersey/ Holstein oviduct epithelial cells, or Holstein/Japanese Black cumulus cells. Transmission of mtDNA was analyzed by PCR mediated single-strand conformation polymorphism of the D-loop region. In six of seven animals sampled postmortem, heteroplasmy were detected in various tissues, while D-mtDNA could not be detected in blood or hair samples from four live animals. The average proportion of D-mtDNA detected in one NT cow was 7.6%, and those in other cows were <5%. Heteroplasmic NT cows (n = 6) generated a total 12 G(1) offspring. Four of 12 G(1) offspring exhibited high percentages of D-mtDNA populations (range 17-51%). The remaining eight G(1) offspring had slightly or undetectable D-mtDNA (<5%). Generally, a genetic bottleneck in the female germ-line should favor a homoplasmic state. However, proportions of some G(1) offspring maintained heteroplasmy with a much higher percentage of D-mtDNA than their NT dams, which may also reflect a segregation distortion caused by the proposed mitochondrial bottleneck. These results demonstrate that D-mtDNA in NT cows is transmitted to G(1) offspring with varying efficiencies.     

Can spermatozoa with abnormal heads gain access to the ovum in artificially inseminated super- and single-ovulating cattle?

The collective efficiency of barriers in the female tract against spermatozoa with abnormal heads was studied. In Experiment 1, Day 6 ova/embryos were recovered nonsurgically from superovulated (n = 24) and single-ovulating (n = 44) cows following artificial insemination with semen of bulls selected for normal spermatozoal motility (> or = 50%) and high content (> 30%) of spermatozoa with misshapen heads, random nuclear vacuoles or the diadem defect. To assess characteristics of spermatozoa capable of traversing barriers in the female tract, accessory spermatozoa were classified morphologically (x 1250) and compared with those of the inseminate. Superovulated cows proved inadequate for assessment of accessory spermatozoa due to evidence of poor sperm retention in the zona pellucida; thus, only single-ovulating cows were used. Accessory spermatozoa (n = 479) from 31 ova/embryos recovered from 44 cows were more normal in head shape than those in the inseminate (76 vs 62%; P < 0.05). Spermatozoa with normal head shape, but with nuclear vacuoles appeared as accessory spermatozoa at the same frequency as they were found in the inseminate (20 vs 17%, respectively). Only sperm cells with subtly misshapen heads appeared as accessory spermatozoa. In Experiment 2, semen pooled from 4 bulls having large numbers of spermatozoa exhibiting a gradation from severely asymmetrically misshapen heads to subtly misshapen heads was evaluated. Again, the accessory sperm population (960 sperm cells recovered from 64 ova/embryos) was enriched with spermatozoa of normal head shape relative to the inseminate (53 vs 26%, respectively; P < 0.05). Sperm cells with only nuclear vacuoles and those with subtly misshapen heads were not different between the accessory and inseminate populations (11 vs 8%, and 20 vs 25%, respectively). We conclude that morphologically abnormal spermatozoa are excluded from the accessory sperm population based upon severity of head shape distortion.     

Normal development of fetuses resulting from Holstein semen processed for sex separation

Semen from two high fertility Holstein bulls with extensive histories in artificial insemination was specially processed for the purpose of sexing and then frozen. The semen was used to inseminate 200 open crossbred beef heifers carefully selected for reproductive soundness from a much larger group. Animals were inseminated alternately with the semen from one of the two bulls and subsequently slaughtered. There were 96 fetuses, ranging in age from 63 to 88 days, which were carefully examined for general appearance, fetal crown-rump length and body weight. There was no effect of sire on fetal size, but the difference between fetal sexes was significant, with the male fetus being appreciably heavier. The regression of fetal length on fetal age was linear and the regression of fetal weight on fetal age was curvilinear. Fetal age accounted for 92% to 96% of the variation in fetal weight and also in crown-rump length.     

Use of F1 progeny of HolsteinxZebu cross cattle as oocyte donors for in vitro embryo production and gene microinjection

This study was designed to determine the possibility of using F1 crossbreed cattle (Holstein x Zebu) as donors of oocytes for in vitro fertilization (IVF) and for pronuclear gene microinjection into in vitro-produced embryos. In the first part of the experiment oocytes from Bos taurus (Holstein), Bos indicus (Zebu) and F1 crossbred Bos taurus x Bos indicus (Holstein x Zebu) genotypes were inseminated with Bos taurus (Holstein) semen and were allocated for in vitro embryo production using conventional IVF procedures. No differences were observed on the in vitro maturation (IVM) rates between breeds (Holstein x Holstein:85%, Zebu x Holstein:84% and Zebu x Holstein x Holstein:88%). Holstein cows yielded the highest number of cumulus oocyte complexes (6.8 per ovary) for in vitro maturation, differing (P<0.05) from Zebu x Holstein and Zebu x Holstein x Holstein F1 by 5.1 and 5.8, respectively. However, the Holstein breed also yielded the lowest percentage of cleavage (45.1 vs 71.9% for Zebu x Holstein and 65.1% for Zebu x Holstein x Holstein). Of the 3 genotypes, the hybrid F1 breed was the most efficient source of oocytes for the production of embryos capable of reaching morulae and blastocyst stages (76 250 ; P< 0.001). In the second part of the study, 599 oocytes from the F1 breed were fertilized in vitro, 1 group of 150 oocytes was used for the determination of the optimal pronuclear visualization period. The highest number of oocytes with 2 pronuclei was observed between 24 to 28 h after IVF (27 to 42%). The remaining 399 oocytes were microinjected with a gene construct bearing the bacterial lacZ gene as the reporter for gene expression. Survival of embryos to microinjection was 73.8%, and 45.5% of them (50 110 ) cleaved in culture. Of the microinjected embryos, 1 out of 50 showed beta-galactosidase activity. These findings indicate that a tropical crossbreed of cattle (Zebu x Holstein x Holstein) can be used as a source of oocytes for IVF programs and gene microinjection studies.     

Effectiveness of lipopolysaccharide as an intrauterine immunomodulator in curing bacterial endometritis in repeat breeding cross-bred cows

Antibiotics are usually used to combat microbial infections of the uterus, responsible for hindering establishment of pregnancy in cross-bred cows. The major disadvantages of antibiotics are: development of bacterial resistance, high costs and diminishing uterine defense mechanisms (UDM). As an alternative therapy, intrauterine application of Escherichia coli Lipopolysaccharide (E. coli LPS) as a uterine defense stimulator was used in this study in confirmed clinical cases of repeat breeding associated with bacterial endometritis. In the treated group (n=12), on the day of estrus, 100 microg of E. coli LPS dissolved in 30-ml sterile phosphate buffer saline (PBS) was infused intrauterine; while in the control group (n=12), only 30 ml of PBS was infused. Six-hour post-treatment, in the treatment group uterine washings showed a 100-fold increase in the total leucocytic count (TLC). Out of the cellular contents, more than 80% of the cells were recognised as neutrophils; above 60% were alive and their phagocytic activity was five bacteria/neutrophil. Such a cellular response was maintained until 72-h post-treatment. At the subsequent estrus period, the cervicovaginal mucus (CVM) became clear in 9 out of 12 cows (75%) and showed no bacterial growth. In the control group, similar micro-organisms were present in CVM of all the 12 cows before and after the PBS infusions. During the subsequent estrus, all nine cows with sterile CVM in the treatment group conceived while only one cow conceived from the control group. It was concluded that, administration of intrauterine E. coli LPS as single infusion in cows with bacterial endometritis stimulated UDM and cleared the infection within one estrous cycle, and thereby restoring fertility.     

Applications of sexed semen in cattle production

Sexed semen will contribute to increased profitability of dairy and beef cattle production in a variety of ways. It could be used to produce offspring of the desired sex from a particular mating to take advantage of differences in value of males and females for specific marketing purposes. Commercial dairy farmers, those who produce and market milk, could use sexed semen to produce replacement daughters from genetically superior cows and beef crossbred sons from the remainder of their cow population. To increase the rate of response to selection, seedstock dairy cattle breeders could produce bulls for progeny testing from a smaller number of elite dams by using sexed semen to ensure that all of them produced a son. Using sexed semen could then reduce the cost of progeny testing those bulls, because fewer matings would be necessary to produce any required number of daughters. Commercial beef cattle farmers, producing animals for eventual slaughter, could use sexed semen to capitalize on the higher value of male than female offspring for meat production. They could also use sexed semen to produce specialized, genetically superior replacement heifers from as small a proportion of the herd as possible. This would allow the remainder of the herd to produce male calves from bulls or breeds with superior genetic merit for growth, feed conversion efficiency, and carcass merit. Single-sex, bred-heifer systems, in which each female is sold for slaughter soon after weaning her replacement daughter, would be possible with the use of X-chromosome-sorted semen. Use of sexed semen would make terminal crossbreeding systems more efficient and sustainable in beef cattle. Fewer females would be required to produce specialized maternal crossbred daughters, and more could be devoted to producing highly efficient, terminal crossbred sons.     

No incidence of DUMPS carriers in Polish dairy cattle

DUMPS (Deficiency of Uridine Monophosphate Synthase) is a hereditary recessive disorder in Holstein cattle causing early embryo mortality during its implantation in the uterus. The only way to avoid the economic losses is early detection of DUMPS carriers. Because American Holstein semen has been intensively imported to Poland since 1970, there was a risk that DUMPS could have spread in Polish dairy cattle. In our study, 2209 dairy cattle of the Polish Holstein breed have been screened by the DNA test. The dominant group was young bulls entering the testing program (1171) and proven bulls (781). They represented all sires entering Polish breeding programs between 1999 and 2003. Also, 257 sire dams were included in the screening program. No DUMPS carrier has been found. Our results then indicate that the population of dairy cattle reared in Poland is free from DUMPS. Because of the economical significance of the DUMPS mutation and its recessive mode of inheritance, attention has to be paid to any case of a bull having in his origin any known DUMPS carrier. Such a bull should be tested and if positive eliminated from the active population. Also, young bulls (testing bulls) should be screened for DUMPS if in their progeny a high incidence of embryo mortality is observed and their genealogy cannot exclude their relatedness to any DUMPS carriers.