ABSTRACT
Reproductive variables in Suffolk Down ewes as a function of the age of the dam

Christian Crempien L.1 y Julia Avendaño R.2
 

Production records for a period of 8 years and 1,552 entries of Suffolk Down ewes, up to seven years of age and six lambing seasons, were analized to obtain correlations for the reproductive variables observed at lambing on the age of the dam. The variables studied were: 1) ewes lambed/ewes present at mating (OP/OPE), 2) dry ewes/ewes present at mating (OS/OPE); 3) lambs born/ewes present at mating (CN/OPE); 4) lambs born/ewes present at lambing (CN/OPP): 5) lambs born/ewes lambed (CN/ OPl; 6) single lambings/total lambings; 7) double lambings/total lambings, and 8) cuocient of single lambings/double lambings (U/D). AII the equations, their coefficient of correlation and the degree of significance are listed below. in the same order:

1. Y = 66.700 + 10.690x -1.260x2 r = 0.981 (P 0.01)
2. Y = 19.284 -5.764x + 0.768x2 r = 0.899 (P 0.05)
3. Y = 51.254 + 25.038x -2.834x2 r= 0.971 (P 0.05)
4. Y = 56.617 + 23.846x -2.699x2 r = 0.983 (P 0.01)
5. Y = 85.635 + 14.100x -1.431x2 r = 0.962 (P 0.01)
6. Y = 122.898 - 23.205x + 2.328x2 r = 0.946 (P 0.01)
7. Y = -22.310 + 22.878x -2.293x2 r = 0.943 (P 0.01)
8. Y = 13.201 - 4.605x + 0.454x2 r = 0.951 (P 0.01)

Keywords:
1 Estación Experimental La Platina (lNIA), Casilla 439, Correo 3, Santiago, Chile.
2 Subestación Experimental Cauquenes (lNIA), Casilla 165, Cauquenes, Chile.