Belgian Blue Research Articles

98 What We Think We “know” About Beef X Dairy Crossbred Cattle in the Feedlot

Abstract To increase profitably, dairy farms across the United States have rapidly adopted breeding a portion of their cows to beef sires, generating crossbred progeny. The resulting progeny have, in some cases, increased the value of the calf to the dairy, due to their perceived potential for improved growth, feed efficiency, and carcass characteristics for beef production. U.S. research is behind our European counterparts in recommending the appropriate beef sires for dairy matings, and U.S. semen trends show Angus sales over many other breeds. However, Kempster et al. (1982) reported that calves sired by British breed bulls were actually at a disadvantage in growth performance compared to even purebred Holstein calves. Finnish researchers agreed, reporting that the resulting crossbreds from Aberdeen Angus and Hereford bulls were extremely variable, making them undesirable for beef production. However, resulting crossbred calves from late maturing breed types (Charolais, Limousine, and Simmental) had better average daily gain and carcass characteristics than their counterparts from early maturing breeds (Huuskonen et al., 2013). A comprehensive review of early crossbred systems similarly suggested that calves sired by Continental breeds, like Charolais, had an advantage in the feedlot and the packing house (Shank, 2003). Going a bit further, another European study examined the used of 3 beef breeds (Belgian Blue, Limousine, and Galacian Blonde) known for heavy muscling, but not common in the United States, for use as crossbreeding sires (Fouz et al., 2012). Holstein cows bred to Belgian Blue sires had the greatest difficulty calving; however, calving difficulties were reduced with increasing dam age (Fouz et al., 2012). Unfortunately, that trial did not go on to evaluate feedlot performance. Thus, there remains a dearth of scientific references for crossbred mating decisions as well as subsequent growth performance and carcass outcomes.

Genetic Variations and Haplotypic Diversity in the Myostatin Gene of Different Cattle Breeds in Russia.

Simple SummaryThis paper presents the results of the study of two polymorphisms of the myostatin gene associated with muscular hypertrophy in the Russian populations of Aberdeen Angus, Limousin, Simmental, and Belgian Blue cattle breeds. For their diagnostics, test systems based on modern molecular genetic methods were developed, and the population analysis showed a low frequency of the undesirable allele associated with the genetic defect of double-muscling, and a high frequency of the allele that presumably positively influences meat productivity traits.The myostatin gene (MSTN) in cattle has a number of polymorphisms associated with increased muscle mass. The aim of the current study was to determine the haplotype frequencies of F94L and nt821(del11) MSTN polymorphisms among cattle bred for meat in Russia, using DNA analysis. Using the earlier created test systems based on the AS-PCR and PCR-RFLP methods, six populations of Aberdeen Angus (n = 684), two populations of Limousin (n = 54), one population of Simmental (n = 55), and one population of Belgian Blue (n = 137) belonging to Russian farms were genotyped on nt821(del11) and F94L MSTN polymorphisms. The animal carriers of the mutant allele of nt821(del11) MSTN associated with the double-muscling genetic defect were found in one Aberdeen Angus population at a frequency of 2.18%, but were not found in the Limousin and Simmental populations. However, 100% of the Belgian Blue population were heterozygous carriers of nt821(del11) MSTN. The frequencies of the A allele F94L MSTN desirable for productivity traits in the Limousin populations were the highest and accounted for 0.97 and 1 in populations one and two, while in the Aberdeen Angus, Simmental, and Belgian Blue populations, these figures were considerably lower at 0.04–0.08, depending on the population. The obtained data show the high genetic potential of Russian beef cattle, and facilitate an improvement in meat productivity by preserving the health of animals.

Bovine besnoitiosis in a cattle herd in Sicily: an isolated outbreak or the acknowledgment of an endemicity?

Bovine besnoitiosis is a debilitating infectious disease caused by Besnoitia besnoiti (Apicomplexa; Sarcocystidae). The disease is mainly characterized by cutaneous and systemic signs, infertility in bulls, and abortion in cows. The current study describes an autochthonous outbreak of bovine besnoitiosis in Sicily, Southern Italy, being the first report of B. besnoiti infection in the island so far. In a cattle farm located in Syracuse province, a 4-year-old Belgian blue bull born in Sicily displayed typical clinical signs of the sub-acute/chronic disease phase with thickening of the skin of the scrotum and testicular degeneration. Histological examination of scrotal biopsies revealed the presence of several tissue cysts of B. besnoiti. The serological analysis of the herd using a commercial ELISA revealed a high seroprevalence (45 out of 55; 82%) of antibodies against B. besnoiti. Few seropositive animals (5 out of 45; 11%) showed clinical signs, cysts in vestibulum vaginae (1 out of 31; 3.2%), and testicular degeneration (4 out of 14; 28.6%) assessed by ultrasonographic investigations. The paucity of clinical signs associated with the high seroprevalence in the farm led to hypothesize that bovine besnoitiosis is endemic in the area though further studies are needed. Local practitioners should be more aware of the disease to facilitate the early detection of cases, prevent the spread of infection, and avoid economic losses and animal health problem.

Environmental temperature and relative humidity differently affect the sperm characteristics in Brown Swiss and Belgian Blue bulls.

In a temperature-increasing scenario, due to global warming, the individual thermic resilience of the male assumes a crucial role in the reproductive efficiency of a male since the thermic stress, such as the inability of the male to reduce body or regional temperature on a physiological level, impairs testicular function. In this study, the effect of the environmental conditions on the fresh semen quality, in terms of volume, concentration, total sperm in the ejaculate, total motility, normal morphology, membrane integrity, and discarding rate, were compared longitudinally in Belgian Blue (BB) and Brown Swiss (BS) bulls. The environmental conditions, summarized in the mean temperature-humidity index (THI), were calculated on the day of collection, as well as 7days (epididymal maturation), 35days (late spermatogenesis), and 70days (early spermatogenesis) before the collection, to reflect spermatogenesis time. Our findings showed that limited seasonal effects were present in the semen quality of BS bulls. On the other hand, in BB bulls lower semen quality was found between July and November, with a different timing depending on the seminal parameter. This effect of the season on BB semen parameters appears to be related to the THI. The data presented in this study shows that the temperature and humidity, summarized in THI, could affect the semen quality of the bull on breed basis,given that volume, concentration, total sperm in the ejaculate, total motility, membrane integrity, and sperm normal morphology were significantly reduced by an increasing THI in the Belgian Blue bulls, but not in Brown Swiss bulls.

The genetic diversity of heat shock protein 70 gene at promoter and 5' untranslated region in beef cattle

This study was aimed to identify genetic diversity in the promoter area and 5' UTR (untranslated region) HSP70 (heat shock protein 70) gene in several beef cattle in Indonesia. A total of 86 blood samples of Bali, Madura, PO (Peranakan Ongole), Limousine, and BB (Belgian Blue) cattle were used in this study. The extracted DNA of all blood samples was then analyzed using the direct sequencing method. The genotyping results showed the presence of five SNP (Single Nucleotide Polymorphism) in the promoter region, namely g.-393T>C, g.-343C>A, g.-202T>C and g.-69T>G and three SNPs at 5' UTR, i.e., g.19A>G, g.45C>T, and g.100_101ins30. The frequency of SNP alleles found in PO, Limousine, and BB cattle was in equilibrium, whereas in Bali and Madura cattle populations, the allele frequency was disequilibrium. In general, the level of diversity of observed alleles ranged from low to high (0.26-1.00), where SNP g.19A>G had the widest variety. It was successfully revealed in this analysis that the SNP g.-69T>G binds to both the NF-Y and CAAT box transcription factor. In addition, the 30 bp (base pair) insertions (g.100_101ins30) that were identified in Bali and Madura cattle have never been reported in previous research studies.

A single nucleotide polymorphism of CAPN1 gene region 3’UTR in Bali cattle

Bali cattle (Bos javanicus), as Indonesian origin genetic resources, is domesticated from banteng (Bibos banteng). Bali cattle have the potential to be developed as producer of premium beef. Genes that have important role in meat quality are calcium-activated neutral protease genes, as known as calpains (CAPN). Calpains are classified as Ca2+ dependent intracellular cysteine proteases, including the ubiquitously expressed μ-calpain (CAPN1) and m-calpain (CAPN2). The purpose of this study was to analyze single nucleotide polymorphism (SNP) region 3’UTR CAPN1 gene in beef cattle. Polymorphism of CAPN1 gene was analyzed by direct DNA sequencing method in 42 Bali cattle that compared with 11 Belgian Blue, 7 Limousine, 12 Pasundan, and 12 Katingan. The result showed that CAPN1 gene has 7 polymorphic SNPs (g.15284 C>T, g.15347 T>G, g.15525 G>A, g.15674 C>T, g. 15853 G>A, g.15905 G>A and g.15915 G>A) in Bali cattle. These SNPs that polymorphic in Bali cattle were monomorphics in Belgian Blue, Limousine, Pasundan and Katingan cattle. Only one SNP g.15853 G>A in Bali cattle was polymophics in Belgian Blue. Deletion was detected that 8 nucleotides deletion (CTCCCTCC) occurred in Bali, Pasundan, and Katingan cattle at position g.15795 – g.15802, while Belgian Blue and Limousine cattle the deletion was not found.

Herd solutions from genetic evaluations can be used as a tool to rescale the expected expression of genetic potential in cattle.

The objective of this study was to determine whether response to selection for carcass weight (CW), conformation (CC) and fat (CF), and the association between heterosis and carcass performance varied by herd environment in cattle. Following edits, carcass information was available for 4,616,761 cattle, of which the majority were some crossbred combination of the following breeds: Angus, Aubrac, Belgian Blue, Blonde d'Aquitaine, Charolais, Hereford, Holstein-Friesian, Jersey, Limousin, Saler, Shorthorn and Simmental. Herd environment was defined separately for each carcass trait using herd solutions outputted from carcass trait genetic evaluations. A total of 3,859 herds were stratified, for each trait, into one of five strata based on their corresponding percentile herd solution rank, with the response to selection and the effect of heterosis then estimated within each stratum. The response in CW and CC from selection on the respective estimated breeding values (EBV) increased between the lowest (0.71kg and 0.89 CC score increase per unit increase in the respective EBV) and highest (0.99kg and 1.25 CC score increase per unit increase in the respective EBV) corresponding herd stratum. The response in CF from selection on CF EBV, however, reduced between the lowest and highest CF herd stratum (respective increases of 0.93 and 0.83 CF scores per unit increase in CF EBV). In addition, the effect of a unit increase in heterosis coefficient on CW, CC and CF also varied by herd stratum. Furthermore, results (i.e. the area under relative operating characteristic curves) from the present study demonstrated that the response to selection and heterosis effects estimated for the different herd stratum can be used, along with EBVs and the herd solutions themselves, to improve the accuracy of phenotypic predictions. Results from the present study could help producers to make more informed breeding decisions that are bespoke to their herd.

Effect of dietary restriction and compensatory growth on performance, carcass characteristics, and metabolic hormone concentrations in Angus and Belgian Blue steers

Compensatory growth (CG) is the ability of an animal to undergo accelerated growth after a period of restricted feeding. However, there is a dearth of information in relation to the effect of genotype on CG response, thus the objective of this study was to evaluate CG response in two contrasting breed types, namely Aberdeen Angus (AN) and Belgian Blue (BB). Crossbred AN × Holstein-Friesian or BB × Holstein-Friesian steers were assigned to one of two treatment groups in a two (genotypes) × two (diets) factorial design. For 99 days, one group (11 AN and 12 BB) was offered a high energy control diet (H-H) whereas the second group (11 AN and 12 BB) was offered an energy restricted diet (L-H). At the end of the differential feeding period (99 days), both groups of animals were then offered a high energy control diet for a further 200 days. All animals were then slaughtered on day-299 of the study. During feed restriction, L-H had lower DM intake (DMI), had greater feed conversion ratio (FCR) and lower plasma concentrations of insulin, IGF-1, leptin, glucose, urea, betahydroxybutyrate and smaller M. longissimus thoracis or lumborum muscle and fat depths compared to H-H steers. During realimentation, there was no difference in DMI between diets; however, L-H had greater live weight gain compared to H-H steers. Overall, H-H consumed greater quantities on a DM basis, however, had a higher FCR compared to L-H steers. By the end of the realimentation period, there was no difference in plasma metabolite or hormone concentrations, linear body measurements, ultrasonically scanned fat depths, carcass conformation, dressing percentage or fat class between H-H and L-H steers. At slaughter, carcass weights were affected by diet with greater values for H-H compared to L-H steers. Genotype affected measures associated with body composition including pelvic width and both muscle and fat depths (P < 0.05). Overall, L-H had a CG (or recovery) index of 0.52 and did not make up for the loss of gains during the differential feeding period; however, M. longissimus thoracis et lumborum, a tissue of high economic value, recovered completely making it a target of interest for further investigation.

Genetic variation in the first intron and exon of the myostatin gene in several Indonesian cattle populations.

Background and Aim:Myostatin (MSTN), a member of the transforming growth factor-b family, is a negative regulator of muscle mass. This study aimed to detect the genetic variation of the 1160 bp fragment of exon 1 and part of intron 1 of the MSTN gene in several cattle populations raised in Indonesia.Materials and Methods:Polymerase chain reaction products of the MSTN gene amplified from 92 animals representing 10 cattle populations (Peranakan Ongole [PO], Belgian Blue x PO cross, Rambon, PO x Bali cross, Jabres, Galekan, Sragen, Donggala, Madura, and Bali) were sequenced, compared, and aligned with bovine MSTN of Bos taurus (GenBank Acc. No. AF320998.1) and Bos indicus (GenBank Acc. No. AY794986.1).Results:Four nucleotide substitutions (nt 1045 and 1066 in intron 1; nt 262 and 418 in exon 1) and two indels (nt 807 and 869 in intron 1) were synonymous mutations. Among these substitutions, only the nt 262G>C and nt 418A>G loci were polymorphic in all populations, except Bali cattle. The frequencies of the nt 262C (0.82) and nt 418A (0.65) alleles were highest. For the nt 262G>C locus, the CC genotype had the highest frequency (0.66) followed by GC (0.30) and CC (0.03). For the nt 418A>G locus, the AG genotype had the highest frequency (0.52) followed by AA (0.39) and GG (0.09).Conclusion:The results, showing genetic variations in exon 1 and intron 1 of the MSTN gene, might be helpful for future association studies.

The Molecular Bases Study of the Inherited Diseases for the Health Maintenance of the Beef Cattle.

The article highlighted the problem of meat cattle genetic defects. The aim was the development of DNA tests for some genetic defects diagnostics, the determination of the animal carriers and their frequencies tracking in time. The 1490 DNA samples from the Aberdeen Angus (n = 701), Hereford (n = 385), Simmental (n = 286) and Belgian Blue (n = 118) cattle have been genotyped on the genetic defects by newly created and earlier developed DNA tests based on AS-PCR and PCR-RFLP methods. The Aberdeen Angus cattle genotyping has revealed 2.38 ± 0.31% AMC-cows and 1.67 ± 0.19 % AMC-bulls, 0.65 ± 0.07% DDC-cows and 0.90 ± 0.10% DDC-bulls. The single animals among the Hereford cattle were carriers of MSUD and CWH (on 0.27 ± 0.05%), ICM and HY (on 0.16 ± 0.03%). The Simmental cattle were free from OS. All Belgian Blue livestock were M1- and 0.84%-CMD1-carriers. The different ages Aberdeen Angus cattle genotyping has shown the tendency of the AMC- and DDC frequencies to increase in the later generations. The statistically significant increase of DDC of 1.17% in the cows’ population born in 2019 compared to those born in 2015 allows concluding the further development of the DNA analysis-based measures preventing the manifestation of the genetic anomalies in meat cattle herds is necessary.

The impact of elective caesarean section on colostrum characteristics in double-muscled Belgian Blue cows

Identification of factors associated with the quality and quantity of colostrum production has always been a major challenge in cattle industry. In purebred double-muscled Belgian Blue (BB) cows, parturition is mainly performed by elective caesarean section (CS; >90%). However, the CS itself may influence colostrum production characteristics. The present study aimed to evaluate the impact of maternal and newborn calf factors and the duration of the procedure of CS on the quality and quantity of colostrum production in BB cows. The dataset includes 551 records of cow-calf pairs that were presented for an elective CS at the Ghent University veterinary clinic between 2017 and 2019. The quality (measured via a colostrum densimeter) and the quantity (measured via a standard volume scale) of colostrum were measured within 30 min after the end of the CS. Fixed effects were fitted in mixed linear regression models to test for their potential association with colostrum quality (specific gravity; SG) and quantity (liters), and generalized mixed-effects models were constructed to test the associations of fixed effects with the optimal colostrum production index (yes vs no) based on an adequate supply of both colostrum quality and quantity. The fixed effects tested were parity, the gender of the calf, birth weight, duration of CS (min), and season of birth. Our results show that parity (primiparity), duration of CS (longer CS), and calving season (summer) had a significantly negative impact on colostrum production. Concluding, both colostrum quality and quantity can be influenced by intrinsic and extrinsic factors (including duration of CS), which should be considered while feeding newborn calves delivered via CS.

Discovery of SNPs and indel 11-bp of the myostatin gene and its association with the double-muscled phenotype in Belgian blue crossbred cattle.

Determining double muscle based on the myostatin (MSTN) gene in Belgian blue (BB), Peranakan Ongole (PO) and BB×PO crossbred cattle is very important for crossbreeding programs. This study aimed to investigate single-nucleotide polymorphisms (SNPs) and 11-bp deletions in the coding region of the MSTN gene and their relationship with the double-muscled phenotype in BB×PO crossbred cattle. A total of 86 blood samples were collected from 28 individual BB, 43 individual PO, and 15 individual BB×PO crossbred cattle. SNPs and indel 11-bp variation in the coding region of the MSTN gene were found using the sequencing method, followed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique. The MSTN gene in the coding region was detected in four SNPs found in PO cattle and its crossbreed. However, the four SNPs could not differentiate normal and double-muscled phenotypes although they are polymorphic. Moreover, in this study, an 11-bp deletion in exon 3 of the MSTN gene in BB cattle was found. In this case, by applying the PCR-RFLP technique using the restriction enzyme NmuCI (Tsp45I) in indel 11-bp, the genotypes that were successfully observed were +/+, +/del.11, and del.11/del.11.

Unravelling Belgian Blue cattle farmers’ adoption intention towards diagnostic tools: Integrating insights from behavioural economics and socio-cognitive theories

Macrocyclic lactone resistance in Psoroptes ovis mites, causing psoroptic mange, is emerging in beef cattle. Therefore, diagnostic tools that can indicate macrocyclic lactone resistance should be implemented at farms in order to control these parasitic infections and slow down emerging resistance. Unfortunately, the adoption of such tools remains relatively poor. This study explores which beliefs, and behavioural biases that misconstrue these beliefs, underlie farmers’ adoption intention. Five semi-structured focus groups were conducted with Belgian Blue cattle farmers (n = 38). Inductive analysis revealed that farmers’ positive attitudes towards acaricides use and risk perception towards acaricide resistance made them rather reluctant to implement diagnostic tools. In addition, farmers’ susceptibility to acaricide resistance occurring on their farm was weakened by the optimism and availability bias. Deductive analysis revealed that economic reasons, usefulness of the diagnostic tool and contribution to animal wellbeing motivated farmers to adopt such tools (i.e., behavioural beliefs). However, the loss aversion and time discounting bias weakened farmers’ beliefs related to economic reasons. The veterinarian was seen as the responsible actor for implementing diagnostic tools, while colleague-farmers’ opinion related to the diagnostic tool was also valued (i.e., normative beliefs). The latter belief was strengthened by the bandwagon-effect bias. Farmers’ beliefs about economic costs related to the diagnostic tool tended to hinder adoption intention, while the veterinarian’s assistance motivated farmers to implement such tools (i.e., control beliefs). The loss aversion bias also strengthened farmers’ control beliefs related to the diagnostic tools’ perceived costs. As such, this article provides more insights into the (ir)rational factors shaping farmers’ intention to adopt diagnostic tools. These insights might help animal health organisations to design communication strategies to stimulate the adoption of diagnostic tools on beef cattle farms.

Dermal immune responses against Psoroptes ovis in two cattle breeds and effects of anti-inflammatory dexamethasone treatment on the development of psoroptic mange

Psoroptic mange is a common disease of livestock, caused by Psoroptes ovis. Compared to Holstein–Friesian (HF) cattle, the Belgian Blue (BB) cattle breed is highly susceptible to the infestation. However, the mechanism for this difference is still unclear. To determine the factors responsible for this breed susceptibility, the immune response to P. ovis was studied in experimentally infested BB and HF cattle, using clinical signs, histology, immunohistochemical profiling and gene expression analysis of skin biopsies. The mite numbers and lesion area of BB cattle were greater than in HF during the whole study period. Significant influxes of eosinophils in the epidermis and dermis were detected in comparison with the pre-infestation samples in both breeds, with significantly higher eosinophils in BB at 6 weeks post infestation (wpi). Mast cell numbers were unaffected at all stages of infestation in HF, but were significantly elevated relative to pre-infestation in BB cattle at 2 and 6 wpi. The more pronounced cutaneous eosinophilia and higher IL-4 levels at 6 wpi in BB cattle suggest that a Th2-type immune response is underlying the higher susceptibility of the BB breed. In naturally infested BB cattle, development of the psoroptic mange lesions and eosinophils and CD3+ T cell areas were severely depressed after anti-inflammatory treatment with dexamethasone. Together, these results suggest that a stronger Th2-type immune response to P. ovis causes the skin lesions in psoroptic mange in BB cattle and that local anti-inflammatory treatment could potentially be an alternative to control the pathology caused by this parasite.

Influence of birth weight and weaning weight on performance and veal quality

Influence of birth weight and weaning weight on performance and veal quality

Morphometry of Male Reproductive Organ and Sperm Evaluation of Belgian Blue Crossbreed Cattle as a Candidate of Superior Bull

The purpose of this study was to observe the size of reproductive organ and to evaluate the sperm quality of Belgian Blue (BB) crossbreed cattle. This cattle are the crossbreeding result between a female Brahman Cross (BX) cattle inseminated with frozen semen from pure male BB cattle, by Artificial Insemination (IB) method, as a candidate of superior bull. The samples of this study were 2.5 years old (BB1), (BB2), and (BB3) crossbreed cattle. Its process involved general physical examination, genital organ inspection, sperm production, and quality assessment. The data obtained were analyzed through descriptive analysis. The results of this study were the three BB crossbred cattle showed the good appearance of normal reproductive organs with scrotum circumferences of each bull were 40.2 cm, 38.6 cm, and 39.8 cm respectively, and sperm quality of the good and the normal motility values of each bull were 82%, 81% and 80%, viability 84%, 83%, and 86%, and the sperm concentrations of each bull were 2.218 million/ml, 1.986 million/ml and 2.120 million/ml respectively. As a result, it could be concluded that those three BB crossbreed cattle are suitable for being used as a superior bull.

Beef cattle methane emission estimation using the eddy covariance technique in combination with geolocation

Methane emissions of a grazing herd of Belgian Blue cattle were estimated per individual on the field by combining eddy covariance measurements with geolocation of the cattle and a footprint model. This method allows the measurement of outdoor non-invasive methane emissions but is complex and subject to methodological issues. Estimated emissions were 220 ±35 g CH4 LU−1 day−1 (grams of methane per livestock unit per day), where the uncertainty corresponds to the random error and does not include any possible systematic error. Cattle behavior was also monitored and presented a clear daily pattern of activity with more intense grazing after sunrise and before sunset. However, no significant methane emission pattern could be associated with it, the diurnal emission variation being lower than the measurement precision.

DNA analysis of the Russian populations of Aberdeen Angus, Hereford and Belgian Blue cattle.

The use of specialized meat breeds in cattle breeding programs is considered very promising for improving herds' productivity. However, in animal genotype, along with genes that positively affect the productivity signs, there are genes whose mutations, known as genetic defects, negatively affect the health of animals. The aim of the study was the screening of the Russian populations of Aberdeen Angus, Hereford and Belgian Blue cattle on gene mutations associated with the genetic defects of arthrogryposis multiplex (AM), osteopetrosis (OS), developmental duplication (DD), double muscling (M1), hypotrichosis (HY) and maple syrup urine disease (MSUD) as well as the F94L polymorphism of myostatin gene (MSTN) linked with the gene responsible for less fat content in the carcass by means of DNA analysis. In the article, test systems based on the polymerase chain reaction method are presented. The analysis of the Aberdeen Angus () population has revealed 0.19 0.09 % animal M1 carriers, 0.53 0.03 % OS carriers, 1.92 0.09 % AM carriers and 9.00 0.20 % DD carriers. The genotyping of Hereford cattle of Russian populations () has not revealed any individual carriers of MSUD or HY genetic defects. All of the Belgian Blue population () animals were heterozygous M1 carriers. The study of the F94L MSTN polymorphism has demonstrated extremely high frequencies of the desirable allele (0.93 and 0.90) in two Aberdeen Angus populations with an average mean of 0.63 0.08, which was 32 % higher compared to the Belgian Blue population. The results suggest the high genetic potential of the Aberdeen Angus and Belgian Blue cattle, but the existence in the genotypes of the mutant alleles associated with hereditary diseases indicates the risk of uncontrolled use of these breeds.

EVALUATION OF GENETIC DIVERSITY IN SELECTED BEEF BREEDS

The aim of the study was to estimate genetic drift and gene flow related to population structure and genetic diversity in selected beef cattle. For the evaluation of the genetic drift and gene flow among analysed populations, the Bayesian Population Structure Analysis and software Treemix were used. The genetic analysis included two cattle breeds bred in Slovakia (Charolais and Limousine). In addition to the Limousine and Charolais breeds, other beef cattle (Angus N = 90, Belgian Blue N = 4, Blonde d'Aquitaine N= 5, Hereford N = 98 and Red Angus N = 15) were analysed. The 50k Bead chip was used; the dataset consisted of 34,834 SNPs. To avoid detection bias, SNPs with high linkage disequilibrium (r2 = 0.05) were pruned from the database; the final data set consisted of 296 animals and 2,539 SNP markers. Our results reflected four modes of gene flow between Angus, Red Angus, Charolais, Limousine and Hereford. Analysed breeds were not confirmed to influence genetic make-up of Belgian Blue and Blonde d'Aquitaine populations. All migration edges reached weight values below 0.2. The only two migration edges higher in weight was observed, first between the ancestor of Limousine breed into Blond d'Aquitaine, and second among historical ancestor of Hereford breed into Red Angus. Our results reflect that the donor population has made a significant contribution to the recipient population.

Influence of seasonal differences on semen quality and subsequent embryo development of Belgian Blue bulls

Belgian Blue bulls are more susceptible to high temperature and humidity index (THI) than most other cattle breeds. Here, we investigated whether high ambient temperature during summer affected semen quality and subsequent embryo development in Belgian Blue cattle. For this purpose, semen samples were collected from six healthy mature Belgian Blue bulls in March (Low THI group; THI between 30.6 and 56.4) and August 2016 (High THI group; maximum THI of 83.7 during meiotic and spermiogenic stages of spermatogenesis; 14–28 days prior to semen collection) respectively. Motility, morphology, acrosome integrity, chromatin condensation, viability, and reactive oxygen species production were assessed for frozen-thawed semen. Moreover, the efficiency of blastocyst production from the frozen-thawed semen samples of the two groups was determined in vitro. Blastocyst quality was determined by assessing inner cell mass ratio and apoptotic cell ratio. Fresh ejaculates showed a higher sperm concentration in low THI when compared to the high THI group (P ≤ 0.05), whereas semen volume, subjective motility, and total sperm output were not affected (P > 0.05). In frozen-thawed semen, total and progressive motility, viability, and straight-line velocity were lower in high THI compared to the low THI group (P < 0.05), while H2O2 concentration, aberrant chromatin condensation, and abnormal spermatozoa were higher in the high THI group (P < 0.05). Blastocyst rates were significantly higher when low THI samples were used (P < 0.05). Moreover, the total cell number and trophectoderm cells were significantly higher (P < 0.05) in blastocysts derived from low THI samples, whereas the apoptotic cell ratio was significantly higher (P < 0.01) in blastocysts derived from high THI spermatozoa. In summary, our data show that elevated ambient temperature and humidity during summer can decrease the quality of frozen-thawed spermatozoa in Belgian Blue bulls and also affect subsequent embryo development.