The composition of forage crops

Sastry, K. N. Shama (1949) The composition of forage crops. PhD thesis, University of Glasgow.

Abstract

Part I. Analytical methods. The moisture, crude protein and carotene contents of fresh grass were measured directly after cutting. In some cases, a representative part of these samples was dried and the true protein, ash, fibre and other extractive later determined. Other dried grass samples were analysed from residual moisture, crude protein and carotene. Some of the methods normally used for estimating carotene, crude fibre and true protein were subjected to critical consideration and comparison. Part II. The chemical composition of fresh grasses. An established growth of timothy grass (Phleum pratense. L.) in its second year was cut at weekly intervals and the chemical changes determined. As the season advance, protein, carotene and ether extractives decreased, rapidly at first, whilst fibre showed a regular increase over the same period. A number of first year grasses of the type used for hay production were similarly examined and showed that considerable differences existed in their rate of establishment. Timothy developed most quickly meadow fescue (Festuca elatior. L.) most slowly, with perennial ryegrass (Lolium perenne. L.) and cocksfoot (Dactylis glomerate. L.) equal and intermediate. Comparison of these four grasses and the second year timothy on a growth basis showed little difference in crude protein and carotene contents. A highly significant correlation existed between crude protein and carotene in all fresh samples. As a result of the analysis of leaf, stem and whole plant it was concluded that mechanical separation with a view to providing a leaf concentrate type of meal from older grass would not be practicable. Part III. The effect of manurial treatment on grasses. Nitrochalk was applied to a short ley and an established pasture in different amounts and at different times in the year. Of the nine treatments used, heavy spring dressings produced more material and higher protein and carotene contents in the short ley than the same or smaller quantities applied later in the year. Less variation was observed between the effect of the different manorial treatments in the older pasture although the general tendency was for it to respond best to heavy, spring dressings in a similar manner to the younger ley. The high correlation already noted between crude protein and carotene was again found. Part IV. The carotene content of dried grass. It has been shown that loss of water from cut grass by field wilting, whilst desirable from a drying point of view, results in considerable loss of carotene from the grass. A maximum wilting period of one to two hours, depending on weather conditions, is advocated if a high carotene grass meal is desired. Normal commercial practice in producing and bagging grass was found to cause only minor loss of carotene but major losses occurred in storage due to air oxidation. These losses were increased by storage at high temperatures and could only be prevented entirely by removal of the atmospheric oxygen prior to storage. The beneficial effect of reducing the volume of oxygen available is discussed.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: R Waite
• Keywords: Range management
• Date of Award: 1949
• Depositing User: Enlighten Team
• Unique ID: glathesis:1949-73704
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jun 2019 08:56
• Last Modified: 14 Jun 2019 08:56
• URI: https://theses.gla.ac.uk/id/eprint/73704