Abstract: A method for preparing transgenic pigs is disclosed. The method comprises the steps of: obtaining a recently fertilized pig ovum; isolating a first DNA sequence encoding a suitable promoter region; inserting the first DNA sequence into a plasmid cloning vector; isolating a second DNA sequence encoding a porcine growth hormone gene; inserting the second DNA sequence into the plasmid cloning vector; introducing the plasmid cloning vector into the male pronucleus; and, subsequently implanting the ovum into a female pig.

Abstract: The present invention relates generally to the isolation of leukaemia inhibitory factor (LIF) genes from livestock species, the expression of said genes in recombinant vectors and the isolation of the recombinant LIF molecules and the use of livestock species LIF to enhance the in vitro development of an embryo to the implantation stage.

Abstract: A method of regulating the reproductive functions of animals, preferably domesticated ruminants, and veterinary implants for use in such a method are provided. The veterinary implant tablet comprises about 2-15% by weight of a fatty acid salt compression binder, about 25-50% by weight of a directly compressible vehicle selected from the group consisting of calcium phosphate and derivatives thereof, about 1-5% by weight of a granulating agent, and an amount of melatonin effective to maintain blood melatonin at, or above, a natural nighttime level of an animal to be treated for a period of time effective to accelerate an onset of breeding activity in mature animals or to delay an onset of puberty in prepubescent animals. The implant tablet provides a substantially continuous release rate of melatonin so as to maintain blood melatonin at, or above, the stated level. A method for preparing such a veterinary implant tablet is also described.