Preservation of fowl semen in liquid nitrogen: application to breeding programmes.

1. A method of freezing semen of individual males was adapted for use under farm conditions using an automated freezing apparatus. 2. An insemination programme to produce high fertility and hatchability with semen which had been deep frozen for 2 months was devised. 3. Over 90 % fertile eggs with a 90 % hatch of all eggs set was obtained with frozen and thawed semen over a period from the 2 nd to the 12th day after the first of four insemination. The persistency of fertility was also tested and 93, 86.6 and 30.7 % of the eggs were fertile during days 2 to 6, 2 to 8 and 9 to 15 after the last insemination. 4. Corresponding with the high fertility rate, chicks were produced by every hen that was inseminated and from every male whose semen was frozen and stored. The implications for future breeding practices of this successful result are discussed.