Poultry Mr. Skeet asked the Minister of Agriculture, Fisheries and Food to what extent he estimates that the replacement of meat by poultry consumption in the United Kingdom is due to its low cholesterol content. Mrs. Fenner My Department has no estimates of the influence of cholesterol content on the replacement of meat by poultry in the United Kingdom diet. However, since the cholesterol contents of both meat and poultry are similar, it is unlikely to be the reason for increased poultry consumption. Mr. Skeet asked the Minister of Agriculture, Fisheries and Food how many diseases are known by his Department to affect poultry; whether the pattern is changing with the continued application of existing drugs; and to what extent biotechnology through genetic engineering has provided more resilient strains. Mrs. Fenner There are three notifiable diseases of poultry — Newcastle disease, fowl plague and paramyxovirus of pigeons, and innumerable other non-notifiable diseases. There is no evidence that the pattern of any of the diseases is being influenced by the application of drugs. Genetic engineering has been applied to the production of new vaccines in animal disease but to date no improved vaccines have been produced in the poultry field. Mr. Skeet asked the Minister of Agriculture, Fisheries and Food whether factory methods of poultry production show diminishing returns of output with the length of performance of this type of farming. Mr. MacGregor In all laying poultry, egg production reaches a peak some six to eight weeks after commencement of lay; thereafter the rate of egg production slowly declines. Research undertaken over a number of years indicates that the rate of decline in egg laying is lower in birds housed in cage systems than in those kept under other conditions.