François Ménissier

Molecular definition of an allelic series of mutations disrupting the myostatin function and causing double-muscling in cattle

We have determined the entire myostatin coding sequence for 32 double-muscled cattle sampled from ten European cattle breeds. Seven DNA sequence polymorphisms were identified, of which five would be predicted to disrupt the function of the protein, one is a conservative amino acid substitution, and one a silent DNA sequence variant. Four additional DNA sequence polymorphisms were identified in myostatin intronic sequences. In all but two breeds, all double-muscled animals were either homozygous or compound heterozygotes for one of the five loss-offunction mutations. The absence of obvious loss-of-function mutations in the coding sequence of the two remaining breeds points either towards additional mutations in unexplored segments of the gene, or towards locus heterogeneity of double-muscling.

Haplotype diversity of the myostatin gene among beef cattle breeds

A total of 678 individuals from 28 European bovine breeds were both phenotyped and analysed at the myostatin locus by the Single Strand Conformation Polymorphism (SSCP) method. Seven new mutations were identified which contribute to the high polymorphism (1 SNP every 100 bp) present in this small gene; twenty haplotypes were described and a genotyping method was set up using the Oligonucleotide Ligation Assay (OLA) method. Some haplotypes appeared to be exclusive to a particular breed; this was the case for 5 in the Charolaise (involving mutation Q204X) and 7 in the Maine-Anjou (involving mutation E226X). The relationships between the different haplotypes were studied, thus allowing to test the earlier hypothesis on the origin of muscular hypertrophy in Europe: muscular hypertrophy (namely nt821(del11)) was mainly spread in different waves from northern Europe milk purpose populations in most breeds; however, other mutations (mostly disruptive) arose in a single breed, were highly selected and have since scarcely evolved to other populations.

Developing a breeding objective for a French purebred beef cattle selection programme.

Abstract This paper presents a procedure for the development of a breeding objective for a beef cattle breed used in a range of production systems. The five main beef cattle production systems in France were first described and then equations of income and costs as a function of the 25 biological traits to be genetically improved for breeding and production were established. Economic values for individual systems were defined as the first derivative of the herd profit with respect to these 25 traits while the economic values for the overall breeding objective were taken as the average of economic values over the five production systems. An application is presented for the Limousin breed. Sensitivity of the breeding objective to variation in the economic or demographic context was also studied. Breeding traits, especially maternal effects on weaning weight and calving success, were identified as the most economically important traits requiring improvement. Relative economic values were very robust with respect to variations in system frequencies and replacement rates. A dramatic change in the market price for beef (−50%) increased the relative weighting of carcass quality traits to the detriment of breeding traits although a smaller change in beef price (−25%) had no significant effect on the relative economic values.

Age-related changes and location of types I, III, XII and XIV collagen during development of skeletal muscles from genetically different animals.

The ontogenesis of total collagen and of different collagen types was studied in four muscle types from genetically different cattle. Hydroxyproline content was 1.2-fold higher in muscles from cross-bred foetuses with normal muscle growth compared to those of the other genetic types (pure bred with different growth rates, double-muscled breed). A similar tendency was observed for type III collagen content. In all muscles of each animal studied, type XII and XIV collagens were colocated in perimysium. Immunolabelling obtained for type XII collagen was higher during foetal life than after birth, while for type XIV collagen, the opposite result was obtained. Whatever the muscle studied, but especially in semitendinosus muscle, during the foetal and the post-natal period until 15 months of age, immunolabelling with antibody anti-type XIV collagen tended to be more intense in muscles of animals from fathers selected for a low muscle growth capacity compared to those from fathers selected for a high muscle growth capacity. In conclusion, this study shows, that during foetal life, selection according to muscle growth capacity has no significant effect on the contents of total hydroxyproline or type III collagen, but minor effects on collagen localization.

Estimation of genetic parameters of preweaning performance in the French Limousin cattle breed

Summary - Direct and maternal genetic and environmental parameters of preweaning growth and conformation at weaning were estimated in the French Limousin beef cattle field recording program using the tilde-hat approach of Van Raden and Jung (1988) with a sire, maternal grandsire (MGS) and dam within MGS model. The numerator relationship matrix among bulls was included in the estimation. The data available after editing contained 169 391 calves with performance records, from 43 683 dams, 7 265 sires, 5 664 maternal grandsires and 1 605 herds, for the years 1972-1989. The traits involved were: birth, 120-d and 210-d weights, average daily gains from birth to 120-d, from 120-d to 210-d, from birth to 210-d, muscular development (MD) and skeletal development (SD) scores at weaning. Estimates ranged from 0.22 to 0.32 for additive direct heritabilities and from 0.06 to 0.16 for maternal heritabilities. Correlations between direct and maternal genetic effects for these traits were negative, ranging from -0.23 to -0.49. Maternal permanent environmental effects were small for all traits, accounting for 5-9% of the phenotypic variances for preweaning growth performance, and 3% and 4% for MD and SD, respectively. beef cattle / variance components / preweaning growth / conformation score / direct and maternal effects / field data

Étude du caractère culard. VII. – Croissance et musculature des femelles, déséquilibre morphologique au vêlage

A partir d’un échantillon de génisses charolaises culardes et normales accouplées avec des taureaux charolais de chaque type, nous avons précisé l’incidence du caractère culard sur la croissance et la morphologie des femelles après sevrage, ainsi que les conséquences de l’hypertrophie musculaire sur les difficultés de parturition. Le caractère culard s’accompagne de poids supérieurs à la naissance suivi d’un ralentissement de la croissance de I à 3-4 ans. Les troubles de mise bas résultent, d’une part, du déséquilibre pondéral entre mère et fœtus lié à leur forme particulière de courbe de croissance et, d’autre part, des modifications morphologiques du train postérieur du veau et du canal pelvien de la mère.

Genetic variability of the length of postpartum anoestrus in Charolais cows and its relationship with age at puberty.

Fertility records (n = 1 802) were collected from 615 Charolais primiparous and multiparous cows managed in an experimental herd over an 11-year period. The objectives of the study were to describe the genetic variability of the re-establishment of postpartum reproductive activity and the relationship with body weight (BW) and body condition score (BCS) at calving and age at puberty. The length of postpartum anoestrus was estimated based on weekly blood progesterone assays and on twice daily detection of oestrus behaviour. The first oestrus behaviour was observed 69 days (± 25 days s.d.) post-calving and the first positive progesterone measurement (≥ 1 ng mL-1) was observed at 66 days (± 22 days s.d.) for the group of easy-calving multiparous suckling cows. Estimates of heritability and repeatability were h2 = 0.12 and r = 0.38 respectively, for the interval from calving to first oestrus (ICO). Corresponding values were h2 = 0.35 and r = 0.60 for the interval from calving to the first positive progesterone test (ICP). The genetic correlation between both criteria was high (rg= 0.98). The genetic relationships between postpartum intervals and BW and BCS of the female at calving were negative: the genetic aptitude to be heavier at calving and to have high body reserves was related to shorter postpartum intervals. A favourable genetic correlation between age at puberty and postpartum intervals was found (rgbetween 0.45 and 0.70). The heifers which were genetically younger at puberty also had shorter postpartum intervals.

Étude du caractére culard. IX. – Fertilité des femelles et aptitude maternelle

Nous avons comparé la fertilité et la production laitière de femelles Charolaises culardes et normales. La présence du caractère culard chez la femelle entraîne un important retard de la puberté et semble diminuer leur fertilité durant les premières années de mise à la reproduction. Les manifestations du comportement sexuel et les signes de préparation à la mise bas sont moins apparents chez ce type de femelles. L’aptitude maternelle est également affectée par le caractère culard : la production laitière traite des femelles culardes est réduite d’environ 5o p. 100 par rapport à celle de vaches Charolaises conduites de la même façon ; une partie de cet écart est probablement lié à l’effet des césariennes. La quantité de lait produite par ces femelles culardes est insuffisante, dès le 2e mois de lactation, pour nourrir leur veau. Ces observations conduisent à penser que les femelles culardes auraient un taux d’oestrogènes plus faible que les femelles normales ; des études endocrinologiques devraient être entreprises sur ce type de bovin, pour déterminer la nature du déséquilibre hormonal en cause. Ces résultats ôtent tout intérêt à l’emploi de femelles culardes Charolaises pour la reproduction et permettent surtout de chiffrer le coût de la sélection d’une souche de mâles culards destinés à être utilisés, par insémination artificielle, pour le croisement terminal.

Possibilités d'amélioration des conditions de vêlage par sélection. I. – Technique de mesure de l'ouverture pelvienne des bovins

La sélection précoce des reproducteurs sur la taille de leur détroit pelvien antérieur ou le ouverture pelvienne a, peut être considérée comme un moyen de réduire les risques de difficultés de vêlage liés à une incompatibilité morphologique foeto-maternelle. Dans le but de mesurer cette ouverture sur l’animal vivant, a été mis au point un compas qui permet d’estimer, par exploration rectale et après anesthésie épidurale, les dimensions du détroit pelvien antérieur dès l’âge d’un an. L’appareil, les mesures appréciées et la technique opératoire sont décrits. La précision de ces mesures est calculée (coefficients de répétabilité) et comparée à celle des mesures corporelles externes.

Genetic relationship between cyclic ovarian activity in heifers and cows and beef traits in males

Records were collected in an experimental herd over an 11-year period from purebred Charolais heifers (n = 351), cows (n = 615) and young entire bulls (n = 383). The objective of the study was to estimate the genetic relationship between the components of female ovarian activity (age at puberty and postpartum anoestrus length), their growth rate and body condition score and beef traits measured on related bulls. Two methods were used to estimate age at puberty and postpartum anoestrus length: the detection of oestrous behaviour and a test of cyclicity based on plasmatic progesterone assay. This study shows the existence of significant heritability estimates for the different cyclicity traits (h2 between 0.11 and 0.38). Most of the genetic correlation coefficients between ovarian activity and growth rate of females and males are negative and favourable (rg between -0.43 and 0.06). Cyclicity is also favourably related with body condition score in young or adult females (rg between -0.65 and -0.22). The genetic relationship between female ovarian activity and proportion of adipose tissue in the male carcass is, however, close to zero. These results show that an antagonism between male beef traits measured in this study and female ovarian activity is unlikely to be a cause for concern in the short term.