Plant quality and harvest in old meadows grazed by reindeer in spring

Abstract

Dry matter (DM) production and nutritional quality of plants were recorded on an old meadow before, during and after it was grazed by reindeer (Rangifer tarandus tarandus; 15 reindeer ha -1 ) in the spring of 1996 and 1997 in northern Norway. Mean herbage harvest after 54 and 50 days of growth including 25 and 24 days of reindeer grazing was 1217 ± 320 kg DM ha -1 in 1996 and 2297 ± 495 kg DM ha -1 in 1997 respectively. On ungrazed old meadow, in contrast (P 0.05). Crude protein content (% of DM) was 25% early in the growing season in both 1996 and 1997. After 54 and 50 days of growth including 25 and 24 days of reindeer grazing, crude protein content was about 17% of DM in both 1996 and 1997 respectively, compared with about 12% of DM in ungrazed old meadow in both years. In 1997, crude protein content was 13.3% of DM after 50 days of growth including 7 days of reindeer grazing. The grazed and ungrazed old meadow contained about 20% (of DM) water-soluble carbohydrates throughout the summer in both years. Mean plant cell wall content in ungrazed plants harvested after about 50 days was higher (51.5 and 49.1% of DM; P > 0.05) compared with plant cell wall content in grazed meadow (49.0 and 46.4% of DM) in 1996 and 1997 respectively. In vitro dry matter digestibility (%) of herbage harvest using rumen fluid from domestic ruminants was about 10% higher (73.4 ± 0.30 and 75.7 ± 0.28) in samples from grazed meadow compared with ungrazed meadow (66.2 ± 0.93 and 65.4 ± 1.19) in 1996 and 1997 respectively. Reindeer grazing of old meadow in spring maintains the vegetation at a younger phenological stage during the growing season when compared with ungrazed meadow. Therefore grazing increased the quality of the herbage, but decreased herbage harvest under conditions of high grazing intensity.