The effect of crossing Polish Corriedale with East Friesian and meat breeds of sheep on the body weight growth and wool productivity of their lambs.
Body weight and wool production were measured for 858 lambs of 8 breed types and crosses: Polish Corriedale and Friesian ewes and their F1 crosses mated to meat-type sires (Suffolk and Isle-de-France). The trial was carried out in 1982-86. The heaviest birth weights were found in Polish Corriedale (4.82 kg) and (Polish Corriedale × Friesian)×Suffolk (4.92 kg). In Polish Corriedale × Friesian crosses, the direction of crossing affected birth weight. Lambs born from Friesian ewes were heavier than those from Corriedale ewes. Three-breed crossbred lambs born from Polish Corriedale ♀ ×Friesian ♂ ewes were heavier than lambs from Friesian ♀ × Polish Corriedale ♂ ewes. At the age of 3 months the Friesian × Polish Corriedale lambs were lighter (18.38 kg) than the Polish Corriedale × Friesian lambs (23.72 kg), but by the age of 5 months the difference had disappeared. At this stage both crossbred types were heavier than Friesian lambs. At 5 months the heaviest lambs were from the Suffolk crossbreds (33.38 kg). The weight of wool produced was highest in the Polish Corriedale (2.27 kg), whereas Isle-de-France crossbreds had the lowest value (0.98 kg) for 3-breed crossbreds and Friesians had the lowest value of all (0.66 kg). The finest wool was observed in the 3-breed crossbreds with Isle-de-France.