Medycyna Wet. 63 (3), 364-368, 2007
Niżnikowski R., Rant W., Popielarczyk D., Strzelec E., Brudka G.
Influence of birth type and sex on reproductive indices and body weight growth in herds of high prolific Polish Heath sheep
The aim of the study was to compare reproductive traits and body weight growth in Polish Heath (Wrzosówka) breed sheep presently maintained in accordance with breeding standards from 1937. The study was carried out between 2003-2005 on 302 ewes and their lambs up to day 100 of life brought up in a flock under a conservation breeding program. Observations were conducted to define the potential of this breed to further improve, mainly in the direction of slaughter lamb production. The evaluated herd of Polish Heath ewes obtained a high level of reproductive features in accordance with breeding standards. The prolificacy, calculated as the number of lambs born per ewe, was 2.06 and the fertility index, evaluated as the relation of ewes lambed to ewes mated, reached 0.97. The litter size distribution showed 42.1% singles, 65.9% twins and 20% triplet litters and quadruplets. The lamb rearing index was considerably higher in the groups of singles and twins in comparison to triplet born litters. The sex of the lambs did not significantly influence the rearing traits, while in the case of body weight growth up to day 100 of life, rams were heavier than ewe lambs. Additionally, ram lambs had higher daily gains, mainly during the first 28 days of rearing. Generally, the accordance of the studied lambs with breed standards regarding reproductive performance, rearing traits and body weight growth indicates the high level of utility of the breed for slaughter lamb production. Further improvements in the breeding process should include increasing the proportion of twin litters born and reducing single and triplet births.
Keywords: sheep, reproduction