INVESTIGATIONS ON BREED DIFFERENCES IN MILK-YIELD OF SWINE .1. COMMITMENT - METHODOLOGY OF MECHANICAL MILKING AND MILK-YIELD

This paper deals with the methodology of mechanical milking of sows. By a milking machine, especially developed herefore, milk yields of the breeds Pietrain (PI) and German Large White (DE) which differ a lot in weaning performance, were investigated. Milk was taken in two-hourly control intervalls on the days 3, 7,14, 21 and 28 of lactation. During this period of 4 weeks, DE showed a continuous increase in milk yield from 5.05 l on day 3 to 12.8 l on day 28. Secretion rate of PI followed parallel with a quantitative decrease of 2 to 3 liters/day, till a maximum was reached on day 14. Then lactation rates decreased. The difference in yield performance between the two breeds was about 5 l on day 28. This superior milk performance of the DE-sows allowed them to wean 3 piglets per litter more than PI. The advantage of DE over PI stays even after standardization of the litter size on n = 10 piglets. Milk composition, its relation towards breed and lactation day and its meaning for the litter performance will be topic of the second comittment.