Livestock production faces major challenges through the coincidence of major drivers of change, some with conflicting directions. These are:

1. An unprecedented global change in demands for traditional livestock products such as meat, milk and eggs.

2. Large changes in the demographic and regional distribution of these demands.

3. The need to reduce poverty in rural communities by providing sustainable livelihoods.

4. The possible emergence of new agricultural outputs such as bio-fuels making a significant impact upon traditional production systems.

5. A growing awareness of the need to reduce the environmental impact of livestock production.

6. The uncertainty in the scale and impact of climate change. This paper explores these challenges from a scientific perspective in the face of the large-scale and selective erosion of our animal genetic resources, and concludes thai there is a stronger and more urgent need than ever before to secure the livestock genetic resources available to humankind through a comprehensive global conservation programme.

Introduction. The Australian almond [Prunus dulcis (Miller) D.A. Webb] improvement program commenced five years ago with the main aims of developing scion and rootstock cultivars that are better adapted to local conditions, and that provide a superior product for Australian and overseas markets. Approaches used. The program has a number of approaches including breeding, virus detection and elimination, and biotechnology. The classical hybridisation approach aimed at generation of diversity is combined with research into the more targeted techniques of plant tissue culture, genetic fingerprinting, genome mapping and transformation. Cryopreservation research is important for genebank storage, and tissue culture for micropropagation of new rootstocks and for transformation. Material is screened for Prunus Necrotic Ringspot (PNRV) and Prune Dwarf (PDV) Viruses. In addition, work has commenced into identifying Australian isolates of Colletotrichum acutatum, the pathogen causing anthracnose disease of almonds. The work is conducted in collaboration with overseas research groups, to take advantage of the long experience of these programs, and to contribute to the international effort in Prunus improvement. Outcomes from the almond project. The important outcomes achieved after the first five years of the project by the research team are listed.

The toxicity of five cryoprotectants – methanol, DMSO, glycerol, ethanediol and sucrose – on different development stages of zebrafish embryos was investigated. Embryos were exposed to a range of cryoprotectant concentrations for 30 min at room temperature. Post-heart beat stage embryos were more resistant to cryoprotectants than carly embryonic stages. The maximum non-toxic concentrations of cryoprotectants on heart beat stage embryos were 2 M methanol, 2 M DMSO, 1 M glycerol, 2 M ethanediol and 0.5 M sucrose. Gradual stepwise addition did not reduce toxicity. Heart beat stage embryos survived 2 M methanol at room temperature for up to 5 hours, whilst DMSO and ethanediol were toxic after 3 and 1 hour exposure respectively. The effect of the nature and concentration of cryoprotectant, equilibrium time, and cooling rate were investigated during cooling to –30 °C. Methanol was more effective than either DMSO or ethanediol for zebrafish embryo cryopreservation and 0.3 °C/min was found to be the optimum cooling rate. Two-step addition of cryoprotectants, with the higher concentration of cryoprotectants added at 0 °C, improved the results. The best embryo survivals obtained after cooling were 94% at – 10 °C, 72% at – 15 °C, 43% at –20 °C, and 8% at –25 °C, no embryos hatched following cooling to –30 °C. Ice formation within the egg was found to be the main factor affecting survival of the embryos.

Preliminary studies of freshly collected halibut (Hippoglossus hippoglossus) sperm by light microscopy indicated that sperm motility, i.e. the percentage of motile sperm and the duration of fonvard progressive movement, was optimized under conditions of osmotic pressure ranging between 400 and 1100 mOsmol/kg and pH for 6.5-8.5. The quality of sperm, stored in vitro on ice, deteriorated rapidly within a few hours, a charactenstic particularly evident in sperm after freezing and thawing tests. Studies of several cryoprotectants indicated that halibut sperm could be successfully preserved frozen when diluted with 3 parts extender (sucrose: 150 mM, CaCl2: 1.7 mM, MgSO4: 7 mM, glycine: 86 mM and Tris: 30 mM at pH: 8), 10% of 1-2 propanediol and one part sperm (3:l). Additional studies of the motility of seawater-activated halibut sperm were conducted by dark field microscopy under stroboscopic illumination. These observations indicated that fast forward-moving sperm motility, which lasts 60-70 s, is correlated with propagating waves on the full length of the sperm flagellum with an initial beat frequency of 45-50 Hz which abruptly drops to about 10 Hz after 60-80 s. The beat frequency is blocked by KCN (5mM) and NaN3, (1.2mM), on intact sperm. The flagellum beat frequency of demembranated/reactivated sperm is dependent on the ATP concentration in the reactivation solution.

Goldfish embryos of pre-morula, somite formation, optic vesicle, heart formation and pigment formation stages were tested for cryoprotectant toxicity, using DMSO and glycerol at 10, 12 and 15% concentration. Those that showed 50% or more survival were employed for cold shock test, from 24 to 4 °C at the rate of –1 °C/min. Only embryos at the heart formation stage protected with 12% DMSO showed 60% survival and 35% hatching. A group of embryos of that stage went through a freezing and thawing test to temperatures of –15, –25 and –35 °C. They showed 30, 5 and 2% survival and 12, 3 and 1% hatching respectively.

Cryopreservation of sperm is an important component of genetic conservation programs for fish.However, since fish eggs or embryos cannot be successfully cryopreserved and since the mitochondrialDNA is maternally inherited, the mitochondrial genomes of fish populations are presently not beingpreserved in these programs. One method of obtaining eggs from stored materials would be tocryopreserve embryonic cells that could later be transplanted into female recipient embryos, formingchimeras; a proportion of these transplanted cells would be expected to enter the germ line andsubscquently develop into eggs. The hypothesis of this study is that isolated blastomeres of rainbowtrout can be successfully cryopreserved and thawed. The objective of this investigation was to determine if the rate of cooling or the type of container alters cryopreservation success. Isolated blastomeres in a freezing solution containing 8.7% DMSO were subjected to one of two different cooling rates in either 0.5 ml French semen straws or cryovials. Thawed samples were examined using phase contrat microscopy, wkh cells scored as being either intact or non-intact. In the nonfrozen control group, 85.4%f 7.6 ($\bar{x}$ ± S.D.) of the blastomeres were intact. There was no significant difference between the cooling rates used in this investigation based on the proportion of intact cells, but there was a significant (p < 0.002) difference in the proportion of intact cells between samples frozen in French straws (35.9% ± 16.5) and those frozen in cryovials (19.4% ± 4.9).

La tolérance aux basses températures des gamétophytes de l'algue alimentaire Undaria pinnatifida est examinée selon différentes méthodes de cryoconservation. La conservation à -80 °C dans une solution glycérolée à 28 % et celle à −196 °C dans une solution en eau de mer de glycérol à 5 ou 10 % ne permettent que des survies de, respectivement, 9 et 4 jours. Par ailleurs, la viabilité n'est pas affectée par un refroidissement de 5 °C/min et une conservation de 15 minutes à −15 °C sans milieu de cryoprotection mais est fortement diminuée par un stockage de 15 minutes à −30 ou −196 °C, même en présence de DMSO. La réduction de la survie des gamétophytes se traduit morphologiquement par une dépigmentation et/ou une contraction des cellules.