干旱区生态环境知识资源中心

A two year trial with modified continuous pasture of lambing ewes with lambs was conducted in a protected area of the Krkonose National Park (KRNAP) at the height of 1,1150 - 1,250 m above sea level. The objective of the trial was to find and test a procedure of the most economical management of areas with similar conditions and ecological requirements, and also production of biologically genuine lamb meat.

The trial involved the ewes of the Tsigai and Improved Sumava breeds which were tupped by rams of the Tsigai and Suffolk breeds. The lambing ewes were wintering in the foothill area (450 m above sea level) and they were habituated to pasture in the surroundings of the shed along with the lambs born in February to March. When the regrowth in mountainous pastures was satisfactory, the animals were moved to KRNAP, where they were grazing from 17th May to 17th September. The annual precipitation amount in the area is 1,363 mm and the annual average temperature makes 4.7-degrees-C. The lands are sloping, untilled, the pastures were not additionally fertilized. There was no shelter for the animals to hide under. The ewes and the lambs were vaccinated against monieziasis once a year. A portable electric fence was installed in the pasture. Temperature sum and precipitation amounts were recorded in both grazing season (Tab. V).

In the first year, the group of lambs of the genotypes Tsigai (C) an d Tsigai x Suffolk (C x SF) had average weight gain of 172 g per head and day over 120-day pasture (from birth to pasture termination it was 170 g). In the second year, the experimental group of the lambs of the breeds C and Improved Sumava (ZS) showed weight gain of 154 g over 103-day pasture (from birth to pasture termination it was 173 g). As the weight gains from birth to load out were almost identical in both years, we can suppose that the lower growth rate of the lambs in the first years was compensated in pasture while in the second year of the trial the weight gains in pasture were lower when the growth in the shed had been higher. These results do not attain the level in highly productive cultures, but the weight gains in mountainous pasture were not supported by any addition of concentrates to feed ration at all, both for lambs and their mothers. The average five weight of lambs was 36.32 kg in the first year, and 34.19 kg in the second year.

The results for both years being confounded, statistical assessment of the effect of the factors on the live weight of lambs (F-test and t-test) indicated significant differences in the genotypes (between the C and A lambs), sex arid effect of year over the grazing season. On the other hand, there was only a difference between the singles and twins in the early phase of lamb growth. The other effects were not proved to influence the weight at birth, apparently due to considerable impacts of management (nongenetic) factors in the ewes’ pregnancy.

The live weight of ewes in pasture increased by 11.22 kg per head on average. The animal density per 1 ha pasture was 6.07 lambing ewes and 9.52 lambs in the first year (3.07 ewes and 4.81 lambs including reserve areas), in the second year it was 6.26 lambing ewes and 5.18 lambs. The total live weight gain per 1 ha was 262.95 kg (132.90 kg per overall utilized area) in the first year, and 160.80 kg in the second year. The low density of animals and total weight gain per 1 ha are optimum from an ecological view considering utilization of mountainous areas.

The animal habituated to harsh mountainous conditions very quickly. Their health was very good, without any clinical symptoms of diseases and without losses.