Red grouse digested about 85% of the soluble carbohydrates in heather, their main food, about 40% of the crude fat and amounts of lignin, α-cellulose and hemicellulose varying up to 40%. The metabolisable energy of heather was 1.5-1.9 kcal/g (dry basis) and that of lignin 2.25 ± 0.59 kcal/g. The fatty acid composition of the depot fat of tetraonids reflected that of the food eaten, presumably because the fatty acids were derived directly from the food. The nutrient requirements of poultry were compared, on the basis of metabolisable energy, with the nutrient content of heather. By analogy with poultry, nitrogen and phosphrus were the nutrients most likely to be limiting to breeding hen grouse. Wild grouse in November selected henther containing more nitrogen and phosphorus then the current year's growth of the heather available. Scottish ptarmigan eat the three main plants commonly available. These same species are available to Icelandic ptarmigan, but other available species which contain more nitrogen and/or phosphorus or soluble carbohydrates are preferred, apparently because they are more nutritious. The ecology of red grouse populations at two 'rich' moors overlying basic rooks was contrasted with that at two 'poor' moors overlying acidic rocks. Differences in the nutritive value of the heather, associated with differences in phosphorus content, may have caused the higher grouse numbers and better breeding success recorded at the rich moors. Shoot tips of very young heather appeared to be more nutritions than those of older heather, but no changes in chemical composition with age were noted beyond six years.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:593169 |
| Date | January 1967 |
| Creators | Moss, Robert |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU293820 |
Page generated in 0.0013 seconds