SOW CULLING - REASONS FOR AND EFFECT ON PRODUCTIVITY

The duration of productive life in the sow was studied on the basis of a survey conducted in commercial herds from which 106,242 sows were culled during the period 1975-1976. The average number of litters weaned per sow was 4.2. This investigation revealed unproductive periods which had an important effect on the number of piglets weaned per sow present in the herd per year. The main reasons for culling 52,800 sows were as follows: • - failure to breed after one or several matings : 31.0% • - decrease in productivity due to old age : 27.2% • - lameness (leg weakness) : 8.8% • - low farrowing and weaning performances : 8.4% • - sow dying on the farm : 6.5% • - no oestrus : 5.4% • - farrowing difficulties : 4.0% • - abortion : 2.8% • - miscellaneous : 5.9%. Fifty percent of the cullings occurred before the first four litters and 21.2% after the first weaning. Management of the herd, housing and feeding of the young sows seemed to be the major problems in relation to reproductive disturbances. Pure Large White sows and Large White × French Landrace crossbred sows showed the same culling rate through successive litters, whereas the rate of culling of Landrace gilts was higher after the first litter. Technical and economical results might be improved by better management and observation of each animal in the herd to ensure earlier discarding of unfertile sows and by application of a strict herd replacement policy. © 1979.