French Beef Breeds Research Articles

Long-range linkage disequilibrium in French beef cattle breeds

BackgroundLinkage disequilibrium (LD) is a key parameter to study the history of populations and to identify and fine map quantitative trait loci (QTL) and it has been studied for many years in animal populations. The advent of new genotyping technologies has allowed whole-genome LD studies in most cattle populations. However, to date, long-range LD (LRLD) between distant variants on the genome has not been investigated in detail in cattle. Here, we present the first comprehensive study of LRLD in French beef cattle by analysing data on 672 Charolais (CHA), 462 Limousine (LIM) and 326 Blonde d’Aquitaine (BLA) individuals that were genotyped on the Illumina BovineHD Beadchip. Furthermore, whole-genome LD and haplotype block structure were analysed in these three breeds.ResultsWe computed linkage disequilibrium (r2) values for 5.9, 5.6 and 6.0 billion pairs of SNPs on the 29 autosomes of CHA, LIM and BLA, respectively. Mean r2 values drop to less than 0.1 for distances between SNPs greater than 120 kb. However, for the first time, we detected the existence of LRLD in the three main French beef breeds. In total, 598, 266, and 795 LRLD events (r2 ≥ 0.6) were detected in CHA, LIM and BLA, respectively. Each breed had predominantly population-specific LRLD interactions, although shared LRLD events occurred in a number of regions (55 LRLD events were shared between two breeds and nine between the three breeds). Examples of possible functional gene interactions and QTL co-location were observed with some of these LRLD events, which suggests epistatic selection.ConclusionsWe identified long-range linkage disequilibrium for the first time in French beef cattle populations. Epistatic selection may be the main source of the observed LRLD events, but other forces may also be involved. LRLD information should be accounted for in genome-wide association studies.

Mycobacterial Infection of Precision-Cut Lung Slices Reveals Type 1 Interferon Pathway Is Locally Induced by Mycobacterium bovis but Not M. tuberculosis in a Cattle Breed.

Tuberculosis exacts a terrible toll on human and animal health. While Mycobacterium tuberculosis (Mtb) is restricted to humans, Mycobacterium bovis (Mb) is present in a large range of mammalian hosts. In cattle, bovine TB (bTB) is a noticeable disease responsible for important economic losses in developed countries and underestimated zoonosis in the developing world. Early interactions that take place between mycobacteria and the lung tissue early after aerosol infection govern the outcome of the disease. In cattle, these early steps remain poorly characterized. The precision-cut lung slice (PCLS) model preserves the structure and cell diversity of the lung. We developed this model in cattle in order to study the early lung response to mycobacterial infection. In situ imaging of PCLS infected with fluorescent Mb revealed bacilli in the alveolar compartment, in adjacent or inside alveolar macrophages, and in close contact with pneumocytes. We analyzed the global transcriptional lung inflammation signature following infection of PCLS with Mb and Mtb in two French beef breeds: Blonde d'Aquitaine and Charolaise. Whereas, lungs from the Blonde d'Aquitaine produced high levels of mediators of neutrophil and monocyte recruitment in response to infection, such signatures were not observed in the Charolaise in our study. In the Blonde d'Aquitaine lung, whereas the inflammatory response was highly induced by two Mb strains, AF2122 isolated from cattle in the UK and Mb3601 circulating in France, the response against two Mtb strains, H37Rv, the reference laboratory strain, and BTB1558, isolated from zebu in Ethiopia, was very low. Strikingly, the type I interferon pathway was only induced by Mb but not Mtb strains, indicating that this pathway may be involved in mycobacterial virulence and host tropism. Hence, the PCLS model in cattle is a valuable tool to deepen our understanding of early interactions between lung host cells and mycobacteria. It revealed striking differences between cattle breeds and mycobacterial strains. This model could help in deciphering biomarkers of resistance vs. susceptibility to bTB in cattle as such information is still critically needed for bovine genetic selection programs and would greatly help the global effort to eradicate bTB.

P5007 Systems biology approach provides novel insights into gene networks controlling tenderness and meat quality traits across French beef breeds

P5007 Systems biology approach provides novel insights into gene networks controlling tenderness and meat quality traits across French beef breeds

Assessment of finishing beef cattle mortality in a sustainable farming perspective

Cattle mortality has a relevant economic and environmental impact but it has been scarcely investigated in finishing beef cattle farms. Aim of this study was to investigate mortality rate in 45 intensive beef cattle farms located in North-Eastern Italy from 2010 to 2013 and to evaluate potential risk factors affecting it. Information from the Italian National Cattle Movement database, as source of mortality data, were crossed with descriptors of barn features and farm management gathered by an on-farm survey to identify factors influencing mortality at farm level, which could be of direct utility for the farmers to reduce cattle losses. Results showed an overall average mortality rate in the 4-year period of 1.4% ranging from 0% to 5.3%. Mortality occurred within the first half of the finishing period, on average 3.4 months after the arrival at the fattening unit. A multivariate regression model showed that mortality was affected by breed (P=0.020) and by floor type as trend (P=0.083). Pure Charolaise (Odds ratio=1.70, 95% Confidence interval=1.11-2.59; P<0.005) and Limousine breeds (Odds ratio=1.96, 95% Confidence interval=1.26–3.05; P<0.005) showed higher odds for mortality compared to other beef breeds or crosses. Bulls housed on fully slatted floor showed higher odds compared to those on deep litter (Odds ratio=1.45, 95% Confidence interval=1.01–2.08; P<0.005). Season at arrival affected mortality (P=0.013), with summer (Odds ratio=1.45, 95% Confidence interval=1.14–1.84; P<0.005) and autumn (Odds ratio=1.74, 95% Confidence interval=1.27–2.38; P<0.005) being the most critical seasons. Differently from expected, space allowance and barn features such as presence/absence of roof insulation and/or ventilation devices as well as the managerial choice of separating or not newly arrived bulls in a dedicated receiving area for quarantine did not affect mortality. Based on findings from this study, it could be concluded that the avoidance of rearing specialized French beef breeds, of using fully slatted floor and of importing young cattle during warm seasons could be considered as preventive measures to reduce the risk of mortality in intensive beef cattle farms.

Genetic characterization of the Blonde d’Aquitaine cattle breed using microsatellite markers and relationship with three other French cattle populations

This study was conducted to evaluate the genetic diversity of Blonde d'Aquitaine, a well-muscled native French beef breed, and to understand the relationships between Blonde d'Aquitaine, Limousin and Salers. We also compared these three beef breeds to the Holstein dairy breed. For this purpose, a set of 16 microsatellite markers were investigated. The obtained results show that Blonde d'Aquitaine has a high level of genetic diversity. Our study shows also that the French beef breeds have genetic differentiation among them, with approximately 9% of the total variation owing to breed differences. Our results show also that Blonde d'Aquitaine and Salers populations are genetically more similar to each other than to the Limousin.

Effects of polymorphisms in the calpastatin and µ-calpain genes on meat tenderness in 3 French beef breeds1

The objectives of the study were to evaluate allelic frequencies and to test the association of polymorphisms in the calpastatin (CAST) and µ-calpain (CAPN1) genes with meat tenderness in 3 French beef breeds. A total of 1,114 Charolais, 1,254 Limousin, and 981 Blonde d'Aquitaine purebred young bulls were genotyped for 3 SNP in the CAST gene and 4 SNP in the CAPN1 gene. Two of these markers, 1 in each gene, can be found in Australian or American commercial genetic tests. Others have previously been reported in American studies or are newly evidenced SNP. The quantitative traits studied were Warner-Bratzler shear force and a tenderness score evaluated by trained sensory panels. All the SNP were informative in the 3 breeds. Associations of individual markers or haplotypes with traits were analyzed. The results differed in the 3 breeds. The G allele of a CAST marker (position 97574679 on Btau4.0) was found to exert a significant effect on the shear force (+0.18 phenotypic SD; RSD) and tenderness score (-0.22 RSD) in the Blonde d'Aquitaine breed. In the same breed, this marker was associated with another CAST SNP (position 97576054 on Btau4.0) such that the GA haplotype appeared to be associated with tougher meat. Two CAPN1 markers (positions 45221250 and 45241089 on Btau4.0) had a significant effect on both traits in the Charolais breed (from |0.11| to |0.25| RSD). In the same breed, these markers were associated with another CAPN1 SNP (position 45219395 on Btau4.0) such that the ACA and AGG haplotypes appeared to be associated with a tender meat and a tougher meat, respectively. Consequently, the present results indicate that the effects of the markers studied are breed-specific and cannot be extended to all Bos taurus breeds. Further studies are also required to identify other more appropriate markers for French beef breeds.

The challenge and limitations of combining data: a case study examining the relationship between intramuscular fat content and flavour intensity based on the BIF-BEEF database

The BIF-BEEF (Beef Integrated and Functional Biology) data warehouse for muscle biology to predict beef quality gathers data related to bovines, their carcasses and their beef. These data come mainly from three sources: the INRA database named FiLiCol, the European GEMQUAL program and the French QUALVIGENE program databases plus other minor sources. At the beginning of 2011, the BIF-BEEF data warehouse contained 331 745 measurements for 621 variables. Measurements were obtained on eight muscles and/or from 5197 animals (mainly young bulls) belonging to 20 different breeds (mainly Charolais, Limousin, Blonde d’Aquitaine, the three major French beef breeds) from experiments carried out over a 10-year period. A web interface was developed to extract data and to analyse them using basic statistical tools (correlation, variance analysis, etc) with R software. Clearly, since the various experiments were not designed initially to ultimately link together, it appeared very difficult to integrate some data which differ a lot by units, scales or laboratory methods. Ontology will help to address these issues. However, the usefulness of the BIF-BEEF data warehouse is described by studying the relationship in M. longissimus thoracis between intramuscular fat content (IMF) and flavour assessed by sensory panels. When data from different sources or different sensory panels were used, they were corrected for these fixed factors in the regression model. They were also corrected for known sources of variation (sex, breed and age of the animals). On average, the relationship between IMF and flavour was low (partial correlation coefficient r = 0.11) but significant. This relationship was no more significant for breeds with low IMF levels (such as Blonde d’Aquitaine) or for animals with the highest IMF such as steers or females.

Specific features of muscles and meat from ‘AOC’ guaranteed-origin Taureau de Camargue beef cattle

The French AOC Taureau de Camargue guaranteed-origin breed certification was obtained in 1996. This denomination covers two local breeds, di Biou and Brave, and crossbreeds between them. On average, 2000 head of these beef cattle are raised every year, yielding 300 tons of meat. Little research has been done on these breeds, especially on meat quality. The aim of the work reported here was to characterise the muscles of these animals. Two muscles, semitendinosus and triceps brachii, were taken on slaughter from 10 males and 10 females from each of the two breeds. Colour, contractile and metabolic properties, intramuscular lipid contents and fatty acid composition were recorded for each sample. The results obtained highlight special features of the muscles of Taureau de Camargue cattle. Compared with all other French beef breeds, these muscles have a strongly oxidative metabolism, associated with a dark red colour and a very low proportion of IIx fast glycolytic fibers. They also contain very low levels of intramuscular lipids. Analysis of fatty acid composition revealed a particularly favourable dietary profile, with 15–20% polyunsaturated fatty acids and about 10% C18:3 fatty acids. We noted a darkening of the meat in both muscles from both breeds, and a strong propensity for myoglobin oxidation.

Genetic Variability and Linkage Disequilibrium Patterns in the Bovine DNAJA1 Gene

Correlation between expression level of the bovine DNAJA1 gene and meat tenderness was recently found in Charolais longissimus thoracis muscle samples, suggesting that this gene could play an important role in meat tenderness. Here, we report the validation of polymorphisms within the bovine DNAJA1 gene, and the haplotype variability and extent of linkage disequilibrium in the three main French beef breeds (Blonde d'Aquitaine, Charolais, Limousin). Genotyping 18 putative SNPs revealed that 16 SNPs were polymorphic within the breeds tested. Two SNPs were removed from further analyses as one SNP had a low genotyping call rate, while the other SNP was not in Hardy-Weinberg equilibrium. The degree of heterozygosity observed for the remaining 14 SNPs varied between breeds, with Charolais being the breed with the highest genetic variation and Blonde d'Aquitaine the lowest. Linkage disequilibrium and haplotype structure of DNAJA1 were different between breeds. Eighteen different haplotypes, including three shared by all breeds, were discovered, and two to three tag SNPs (depending on the breed) are sufficient to capture all the genetic variability seen in these haplotypes. The results of this study will facilitate the design of optimal future association studies evaluating the role of the DNAJA1 gene in meat tenderness.

The two mutations, Q204X and nt821, of the myostatin gene affect carcass and meat quality in young heterozygous bulls of French beef breeds1

The availability of genetic tests to detect different mutations in the myostatin gene allows the identification of heterozygous animals and would warrant the superiority of these animals for slaughter performance if this superiority is confirmed. Thus, 2 mutations of this gene, Q204X and nt821, were studied in 3 French beef breeds in the program Qualvigène. This work was done with 1,114 Charolais, 1,254 Limousin, and 981 Blonde d'Aquitaine young bulls from, respectively, 48, 36, and 30 sires and slaughtered from 2004 to 2006. In addition to the usual carcass traits recorded at slaughter (e.g., carcass yield, muscle score), carcass composition was estimated by weighing internal fat and dissecting the 6th rib. The muscle characteristic traits analyzed were lipid and collagen contents, muscle fiber section area, and pH. Regarding meat quality, sensory qualities of meat samples were evaluated by a taste panel, and Warner-Bratzler shear force was measured. Deoxyribonucleic acid was extracted from the blood samples of all calves, the blood samples of 78% of the dams, and the blood or semen samples of all the sires. Genotypes were determined for 2 disruptive mutations, Q204X and nt821. Analyses were conducted by breed. The superiority of carcass traits of calves carrying one copy of the mutated allele (Q204X or nt821) over noncarrier animals was approximately +1 SD in the Charolais and Limousin breeds but was not significant in the Blonde d'Aquitaine. In the Charolais breed, for which the frequency was the greatest (7%), young bulls carrying the Q204X mutation presented a carcass with less fat, less intramuscular fat and collagen contents, and a clearer and more tender meat than those of homozygous-normal cattle. The meat of these animals also had slightly less flavor. Also in the Charolais breed, 13 of 48 sires were heterozygous. For each sire, the substitution effect of the wild allele by the mutant allele was approximately +1 SD for carcass conformation and yield, showing that the estimate of the substitution effect was independent of family structure, as it ought to be for a causal mutation. These results illustrate the challenge of using genetic tests to detect animals with the genetic potential for greater grades of carcasses and meat quality.

Calving ability of three French beef breeds: Preliminary results

This short communication summarizes the main results of a factorial crossing experiment between French beef breeds: Charolaise, Limousine, Maine-Anjou, for evaluating their calving ability. Both paternal (birth weight and calf morphology) and maternal (calving weight, pelvic opening and maternal effect on calf size) components have been investigated.