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Herbage use was tested in mixed grazing of cattle and sheep on originally arable lands converted to permanent grasslands. Growth of youngs and live weight of dams were investigated in three grazing seasons, under semi-arid lowland conditions, for a semi-extensive management method, at average dry matter yield of 7.823 t/ha. Rotational grazing in 3-4 paddocks at average stocking 1,874 kg I.w./ha was practised. Sheep representation was 18% on average with a variation of 17-24% throughout the season. Ewes with lambs accounted for 31% of the resultant output 539 kg I.w./ha The fitness of suckling cows and ewes improved over all grazing seasons. Respective increases in live weight per growing season were 50.32 +/- 6.36 kg and 8.68 +/- 0.70 kg. They were reflected in the trend of daily weight gains recorded in calves and lambs in the particular seasons:

1995 - 0.983 +/- 0.049 and 0.190 +/- 0.011 kg

1996 - 1.083 +/- 0.057 and 0.251 +/- 0.008 kg

1997 - 1.139 +/- 0.115 and 0.228 +/- 0.009 kg.

Weather conditions in 1997 were extreme. Differences in daily weight gains of young cattle of different genotypes fluctuated around the average value of the set 0.889 +/- 0.034 kg within a small range. The results of breed groups Czech Pied (C), Blonde d’Aquitaine (BA), Hereford (He), Charolais (Ch) were insignificantly better than the average, while breed groups Limousine (Li), Aberdeen Angus (AA) gave results worse than the average, and statistically significantly lower weight gains were recorded in Piemontese breed (Pi). With respect to daily weight gain of the whole set of all genotypes under observation, lamb group Ch100 gave the best results (0.256 +/- 0.009 kg) and group Bo25Ch showed average values (0.229 +/- 0.010 kg). As for the other breeding characteristics, the best values in this management system were observed in sheep breed Charollais and its commercial crosses with a share higher than 74%.