Welfare assessment and phenotype characterisation of transgenic mice.

Induced mutations can cause new and unpredictable phenotypes and may impact the health and welfare of animals. Impairments may arise within normal husbandry and breeding regimes i.e. before starting to do experiments. In order to apply the 3R principles and to use transgenic animals under high scientific and welfare standards, two structured forms for individual health monitoring and strain characterisation have been developed. They are available at: www.vu-wien.ac.at/labortierkunde or www.altex.ch.

Morphological assessment of preimplantation embryo quality in cattle.

The extensive use of embryo technologies has emphasized the need for assessing embryo quality by morphological techniques, such as transmission electron microscopy, immunocytochemistry for confocal laser scanning microscopy and fluorescence in situ hybridization. By a combination of these techniques, it has been possible to demonstrate: (i) that rRNA gene activation, as monitored by embryonic nucleolar development, is comparable in bovine embryos developed in vivo and produced in vitro, whereas reconstructed nuclear transfer embryos may be deviant, (ii) that generating embryos by both in vitro production and reconstruction by nuclear transfer is associated with increased occurrence of apoptosis, in particular in the inner cell mass of blastocysts, and (iii) that these two embryo production techniques are associated with increased occurrence of mixoploidy that is, embryos presenting a large population of normal diploid cells and a small population of abnormal haploid or polyploid cells. It is clear that blastocysts that appear healthy at stereomicroscopy may have subcellular defects. Therefore, the possibility of long-term evaluation in vitro of embryos after hatching has been examined. However, whereas embryos developing in vivo after hatching present a number of well defined developmental milestones, such as elongation of the trophoblast, formation of hypoblast and epiblast followed by differentiation of endoderm, mesoderm and ectoderm, in vitro culture systems for development beyond the blastocyst stage currently allow the embryo to complete only a single milestone, namely hypoblast formation.

Reciprocal translocations in pigs. Their detection and consequences on animal performance and economic losses.

In France, the national computerized program for sow herd management regularly delivers a listing of hypoprolific boars for which a cytogenetic evaluation is required, and participates in the differential diagnosis of the other causes of reduced prolificacy. Two reciprocal translocations, 4/14 and 7/15, reducing the prolificacy by about 45 percent have been discovered since 1979. A third one, leading to a prolificacy reduction of about 28 percent, is described in the present paper. The effects of translocation 4/14 were studied in an experimental herd, in which the ovulation rate did not seem to be modified and the early embryonic mortality accounted for the decrease in litter size. The growth rate at day 35 was higher in piglets carrying the chromosomal abnormality than in their normal littermates, i.e., 215 vs. 182 g per day (P less than 0.10). The economic consequences of using a boar carrying a translocation on a group of 21 sows were estimated by means of a simulation model "Porsim." When prolificacy decreased by five piglets per litter, the losses represented 157 piglets, i.e., about $4000. If, in addition to this, the percentage of non-returns into heat decreased by 35 percent, the losses then represented 248 piglets, i.e., $6000. Because of this important economic risk, it is suggested that measures be taken to detect defective animals and to prevent their use.

[The frequency of chromosome abnormalities in farm animals and their economic consequences]. / L'incidence des anomalies chromosomiques chez les animaux de ferme et leurs conséquences économiques.

Examinations during the last two decades of the chromosome complements of various species of domestic animals have revealed the existence of a considerable number of abnormalities, including inherited rearrangements: approximately 20 in cattle, 15 in pigs (predominantly reciprocal translocations), 3 in sheep, 2 in horses (predominantly monosomy X), and 1 in goats. (The accumulation of data on the frequency of such abnormalities and evaluation of their effects on reproductive performances of carriers of inherited rearrangement depends on a number of factors including the use of artificial insemination, number or progeny per sire or dam, and differences in generation intervals of the species concerned). The economic value of the cytogenetic findings depends on the degree of exchange of information between the breeders and the cytogenetics laboratories. An example of a successful collaboration is a Swedish study of a centric fusion translocation in Swedish Red and White cattle, one that affects chromosomes 1 and 29. There, the fertility-reducing effects of the translocation led to a loss of approximately $250,000. Recognition of the significance of the translocation prompted a search for carrier bulls and their elimination from the artificial insemination units. In swine, in which artificial insemination is used much less than in cattle, data on the frequency of reciprocal translocations in general must be obtained from the farms themselves. The main effect of an inherited chromosome rearrangement is a reduction in the number of offspring, perhaps to 50%, i.e., five piglets per litter.(ABSTRACT TRUNCATED AT 250 WORDS)