[Studies on cattle in anoestrus (author's transl)].

One of the items of a herd management programme concerned with reproduction consists in a study of those animals which have not yet come into oestrus within fifty to sixty days after parturition. On twenty farms, an inventory was made of the causes of anoestrus in these animals and the effects of anoestrus on fertility were studied. In addition, studies were done to determine whether there was a possible relationship between the causes of anoestrus and the age of the animals, the season, type of housing and the course of the last parturition and puerperium. Of the total number of 2,720 animals which had calved, 438 (16 per cent) had not yet come into oestrus within fifty to sixty days after parturition. This proportion varied markedly from one herd to another (8-24 per cent). The following causes of failure to come into oestrus were diagnosed: suboestrus (76 per cent), genuine anoestrus (9 per cent), ovarian cysts (2 per cent), pyometra (6 per cent) and gestation (1 per cent). All these changes obviously had an effect on the fertility of the herds (Table 1). Genuine anoestrus was found to occur particularly in primparous cows, whereas ovarian cysts and pyometra were diagnosed in the older cows (Table 2). It also became apparent that suboestrus and genuine anoestrus mainly are problems in tying stalls during the winter season (Table 3). There was not found to be any relationship between the presence of suboestrus or genuine anoestrus and the course of parturition and the puerperium. Fifty-two per cent of those animals in which a diagnosis of pyometra was established, had shown retained placentas (Table 4). In view of the fact that a diagnosis of suboestrus was so frequently established, particular attention should be paid to the detection of oestrus.