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The experiment focused on feed evaluation was conducted with goats to determine the feeding value of two aggressive weeds, the giant goldenrod (Solidago gigantea) and the bushgrass (Calamagrostis epigejos). Studied plants at the pre bloom stage were evaluated for feeding value by 7-month-old castrated goats (n=5 per group, BW=25.0 kg). All animals received no supplemental feed. The two plants differed in content of dry matter (DM) (266 vs. 394 g/kg) as well as in crude protein (119 vs. 86g), crude fibre (222 vs. 317 g) and N-free extract (523 vs. 447 g) per kg DM. In this study, total daily DM intake from giant goldenrod and bushgrass was similar (666 vs. 689 g/goat). Apparent digestibility of these plants was similar for organic matter (58-59%), but differed for crude protein (71 vs 53%) and N-free extract (72-62%). The values of total digestible nutrients (55.9-53.4%), net energy for maintenance (NEm: 4.90-4.54 MJ) and net energy for lactation (NEl: 5.16-4.91 MJ) per kg DM were similar. The study concluded that Solidago gigantea and Calamagrostis epigejos aggressive plants could be interesting feed for goats due to their feeding values. In addition, both of these aggressive weeds are relatively easily available.

Second crops of oil radish (Raphanus sativus) and white mustard (Sinapis alba) being in the bloom stage were evaluated for nutritive value for wether lambs (n=5 per crop, BW=35.6 kg) and in situ grazability by ewes (n=15 per crop, BW=50 kg). Animals received no supplemental feed. The two forage crops differed in dry matter (DM) (135 vs. 154 g/kg) as well as in crude protein (148 vs. 206 g), crude fibre (141 vs. 194 g) and N-free extract (550 vs. 482 g) per kg DM. In the feeding trial, total daily DM intake of lambs from oil radish and white mustard differed (1063 vs. 1203 g/head) but was similar in percent bodyweight (3.3-3%). Apparent digestibility of the two forage crops were similar for crude protein (69-70%) and N-free extract (70-71%), but differed (Pm (5.70-5.88 MJ) per kg DM. In the 4-day grazing trial was used rotational grazing, based on results, the oil radish provided a carrying capacity twice as high as white mustard’s notably, 1700 vs. 740 ewe grazing days per ha - equal to 60 ewes grazing one hectare for 28 and 12 days, respectively. Thus, oil radish seemed better to be used as fall grazing pasture for mutton sheep.

Using portable, non-destructive own developed chambers (d=60 cm) and infrared gas analyses, the in situ field investigation was performed to study the seasonal and inter-annual dynamics of the stand level CO2-flux and production of sandy grassland that has been extensively grazed for decades. Furthermore, NEE measurements and biomass samples were used to identify the initial effects of grazing exclusion on CO2 exchange, aboveground phytomass and potential plant productivity in years of significantly different precipitation levels. A considerable inter-annual variation in all of the studied parameters was found both in the non-grazed and grazed stands. As a result of the grazing exclusion the CO2 uptake potential of the non-grazed stand increased by 13% compared to the grazed stand. It was more significant in the extreme dry year (220%), however, in wet year slightly lower average carbon sequestration was detected at the non-grazed stand (-13%), than that of the grazed area. Significant carbon sequestration potential was only detected during wet periods in both stands. The rate of CO2 uptake was found to be nearly six times higher in the non-grazed stand in the wet year than in the previous extremely dry year. The drought in 2003 significantly reduced the CO2 uptake of both stands, leading to lower annual net primary production and potential plant productivity. The annual net primary production dropped by almost 40% in the extremely dry year but then it rose by nearly two and a half times in the subsequent year with adequate rainfall.