The aim of this work is to evaluate the course of rearing Red Pied heifers reared with use of graze and stable and review effect of graze use on subsequence performance in 1st lactation. In selected breed was monitored process of heifer grow by periodical weighting in three months interval, furthermore was taken for these heifers these reproduction indices: 1st insemination age, insemination index, 1st calve age. Heifers are divided by rearing form (graze, stable) and compared differences in grow intesities and reproduction efficiency between particular groups. Subsequently, for cows on first lactation were monitored and compared these indices: level of milk performance, content of milk elements, degree of physical condition, indices of fertility. Dairy cows are divided into groups according to how they were reared as heifers (graze, stable). When comparing growth of heifers, grazed heifers reaches higher values than group of not grazed heifers. Grazed heifers grows more quickly: at age 3 months was their average weight 93,26 Kg against 88,30 Kg not grazed heifers. At age 6 months was weight of grazed heifers 169,51 kg against 161,80 kg not grazed heifers, At age 9 months was values 236,47 kg for grazed heifers, 228,07 kg for not grazed heifers, at age 12 months 326,62 kg and 299,87 kg, at age 15 months 366,11 kg and 359,98 kg. From reproduction indices have been found statistically significant differences in age at 1st insemination, when the grazed heifers were flushed in average age of 18,43 months against not grazed heifers in age of 17,12 months. In addition, was found statistically significant differences in age at first calving, when the values obtained for the group of grazed heifers was 28.63 months and for not grazed heifers 27,73 months. First calving heifers reared on graze produce in lactation average 7 782,4 Kg of milk, first calving heifers reared in stable produce in lactation average 7 064,40 Kg of milk. Differences was statistically significant. Average duration of lactation at first calving heifers reared on graze was 359,47 days, duration of lactation at first calving heifers reared in stable was 329,01 days. Differences was statistically highly significant. From the linear description is clear that graze has positive effect on heifers muscling and limbs. In overall assessment made grazed heifers higher rating points 81,43 for heifers reared on graze and 81,00 point for heifers reared in stable. These differences could not be statistically demonstrated.

Forage intake by animals is an important factor in determining production of livestock products from rangelands. However, relatively little is known of effects of such forage variables as availability and distribution in space upon intake. Even less is known about how the grazing animal modifies its feeding tactics when confronted with diminishing or limited supplies of available forage and how such altered behavior may affect the animal's energetic cost for existence. Forage intake, body weight gain, grazing time and biting rate of Angus heifers was related to forage availability and plant height on semiarid crested wheatgrass rangeland during the late summer. Forage availability was estimated within 10 percent of the 2 mean (P2plots. Forage intake was estimated from data on fecal production and in vitro digestibility of forage. Fecal production was determined by total collection, using fecal collection bags, and by a single-dose marker technique, used to estimate fecal production indirectly. Digestibility was determined by an in vitro procedure. Additionally crude protein and cell contents of forage were determined. Grazing time was measured by mechanical grazing clocks (Vibracorders) mounted on animals' necks. Biting rate was determined visually using a stop watch to time specific grazing intervals during which all bites were counted. There were a total of four 4-day trials during 1977 and five 4-day trials during 1978. Crude protein content within years was significantly higher during the third period in 1977 and during the fifth period in 1978 when regrowth occurred. Within years, in vitro digestibility was significantly higher only for the fifth trial during 1978. Cell contents decreased as grazing progressed only during 1978. Crude protein content, cell contents and in vitro digestibility were higher during 1977 than 1978. Forage intake of heifers did not vary significantly among successive grazing trials as forage availability declined from 919 to 143 kg DM/ha. Heifers apparently compensated for the diminishing forage availability by increasing grazing time from 380 to 656 min/day and biting rate from 37 to 50 bites/min. Grazing time was inversely related to forage availability and was expressed by the relationship y = 676.8 - 0.3x; r2 = 0.93. Biting rate was less correlated with forage availability and was described as y = 50.4 - 0.02x; r2 = 0.86. However, biting rate was more closely correlated with plant height as described by the relationship y = 53.0 - 0.48x; r2 = 0.95. Heifers maintained or gained 0.1 to 0.7 kg/head/day weight during all trials except the last trial in 1978 when they lost approximately 1.1 kg/head/day. The weight loss for this trial was apparently not a result of restricted forage intake or limited forage quality but partly due to extra maintenance energy expenditures attributable to increased grazing time and biting rate. Correlation between estimates of fecal output by the single dose marker technique with total fecal collection were not significant (P