Preliminary Study of Prolificacy and Maternal Ability on Six Sheep Biotypes in Uruguay

The results of the first evaluation of the Prolific Sheep Project of INIA (2008-2011) demonstrated that the crossbred biotypes Corriedale by East Friesian or Corriedale by Finnish Landrace weaned 60 % more lambs than pure Corriedale and, on the other hand, the crossbred East Friesian by Finnish Landrace weaned 85 % more than pure Corriedale. However, and under the same productive conditions, the behavior at lambing and colostrum production of these new biotypes are unknown. In order to find out, an experiment was conducted at INIA La Estanzuela, Colonia, Uruguay (34°S; 57°O) where 61 female lambs 4-6 teeth born in the spring of 2010 were evaluated. Two pure breeds were used: Corriedale (C.C) and East Friesian (M.M), and the crosses Finnish Landrace x Corriedale (F.C), East Friesian x Corriedale (M.C), 3/4 East Friesian - 1/4 Finnish Landrace (M.(F.M)), 7/8 Finnish Landrace - 1/8 Corriedale (F.(FxF.C)), mated with Texel rams. The increase in Finnish blood resulted in more prolificacy (2.2; 2.3 and 2.4 for 1/4; 1/2 and 7/8 Finnish with lighter lambs and less lambing assistance. Both half and pure East Friesian had similar and moderate prolificacy (1.8 M.C and 1.7 M.M) whereas lambing assistance was high. Colostrum production and composition was similar between biotypes, with the exception of M.M, that produced more. There were no differences in placental efficiency between biotypes. Birth weight of lambs affected their behavior in the first hour of life, specifically the time from birth to first stand up to suckle.