32 research outputs found
Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep
Inheritance of the ovulation rate (OR) in the Lacaune meat breed was studied through records from a small nucleus of 36 hyper-prolific ewes screened on farms on the basis of their natural litter size, and from progeny data of three selected Lacaune sires. These sires were chosen at the AI centre according to their breeding values estimated for the mean and the variability of their daughters' litter size. Non-carrier Lacaune dairy ewes were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve sons (four from each sire) were used in turn to inseminate non-carrier Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC progeny were brought from private farms and gathered after weaning on an experimental farm where ovulation rates were recorded in the first and second breeding seasons. With an average of 6.5 records each, the mean OR of hyper-prolific ewes was very high (5.34), and 38.4% of records showed a rate of 6 or more. F1 data showed high repeatability of OR (r = 0.54) within ewe, with significant variability among ewes. High OR (≥ 4) were observed in each family. A segregation analysis provided a significant likelihood ratio and classified the three founders as heterozygous. BC ewes also displayed high repeatability of OR (r = 0.47) and the mean OR varied considerably between families (from 1.24 to 1.78). Seven of the 12 BC families presented high-ovulating ewes (at least one record ≥ 4) and segregation analysis yielded a highly significant likelihood ratio as compared to an empirical test distribution. The high variability of the mean ovulation rate shown by a small group of daughters of BC ewes inseminated by putative carrier F1 rams, and the very high ovulation rate observed for some of these ewe lambs, confirmed the segregation of a major gene with two co-dominant alleles borne by an autosome. The difference between homozygous non-carriers and heterozygous ewes was about one ovulation on the observed scale and 2.2 standard deviations on the underlying scale
Use of a new container, CBS straw, for biosafe cryostorage of mammalian embryos and its application to the perservation of embryos and its application to the preservation of embryos from a scrapie contamined flock
National audienc
Superovulatory response and quality of embryos recovered from Romanov ewes after a single injection of pFSH dissolved in polyvinylpyrrolidone
National audienc
Superovulation and embryo production in ewes with single or multiple injections of pFSH
National audienc
Studying the seasonality of scrapie transmission in an experimental flock
International audienc
Modélisation de la transmission de la tremblante dans le troupeau de Langlade : Etude de l'effet saison
National audienc
Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep
Inheritance of the ovulation rate (OR) in the Lacaune meat
breed was studied through records from a small nucleus of 36
hyper-prolific ewes screened on farms on the basis of their natural
litter size, and from progeny data of three selected Lacaune
sires. These sires were chosen at the AI centre according to their
breeding values estimated for the mean and the variability of their
daughters' litter size. Non-carrier Lacaune dairy ewes
were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve
sons (four from each sire) were used in turn to inseminate non-carrier
Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC
progeny were brought from private farms and gathered after weaning on
an experimental farm where ovulation rates were recorded in the first
and second breeding seasons. With an average of 6.5 records each, the
mean OR of hyper-prolific ewes was very high (5.34), and 38.4% of
records showed a rate of 6 or more. F1 data showed high repeatability
of OR () within ewe, with significant variability among
ewes. High OR () were observed in each family. A segregation
analysis provided a significant likelihood ratio and classified the
three founders as heterozygous. BC ewes also displayed high
repeatability of OR () and the mean OR varied considerably
between families (from 1.24 to 1.78). Seven of the 12 BC families
presented high-ovulating ewes (at least one record ) and
segregation analysis yielded a highly significant likelihood ratio as
compared to an empirical test distribution. The high variability of
the mean ovulation rate shown by a small group of daughters of BC ewes
inseminated by putative carrier F1 rams, and the very high ovulation
rate observed for some of these ewe lambs, confirmed the segregation
of a major gene with two co-dominant alleles borne by an autosome. The
difference between homozygous non-carriers and heterozygous ewes was
about one ovulation on the observed scale and 2.2 standard deviations
on the underlying scale