Because of the increasing need for ewes which can rear more than two lambs adequately and without shepherding, studies were made in Finland (F), New Zealand (N. Z.) and Ireland on criteria relating the development of such ewes. The Finnish study was based on small trials in 1963—66 and in 1985—88 and on field data from the 1980’s. Data of Vainikainen (1945) was also used. In N.Z., a more systematic experiment has been carried out since 1984, while in Ireland a small study of teat parameters was made in 1985. The frequency of ewes with supernumerary teats (ST) in Finnsheep and Coopworth was ca. 20 %. The frequency of six-teated animals increased with selection for teat number. In Finland, about ½ of the 4-teated ewes had milk-yielding STs. Six-teated ewes in N.Z. gave 30—40 % of their daily milk from the STs. The N.Z. Coopworths seemed to have a »multiple lamb image»; multiple lambs tended to be closely bonded and sucked together, leading to higher success rates than when sucking individually. Heritability of teat number in N.Z. was 0.6. The lengths of STs were more variable than those of main teats, and their mean length ca. half of that of main teats. The average distance of STs from the main teats in Finnish trials was ca. 20 mm (range 1—50mm); the length and separation of teat pairs were correlated, although this was not the case in several flocks studied in Ireland.
Possibilities of developing sheep which suckle from several teats
