The water‐soluble carbohydrates of grasses. II. —Grasses cut at grazing height several times during the growing season

Abstract

Four perennial grasses were cut with a motor mower each time they reached a height of about 8-10 in. during the growing seasons of 1951 and 1952. The water-soluble carbohydrates, glucose and fructose (reported together as free hexoses), sucrose and fructosan were determined in each cut. Grasses in which the growing point had recently changed to a floral development (in May or June) contained more carbohydrate than grass grown and cut later in the season. The primary reason for this was that the later grasses were more leafy, and, secondly, that their stems contained much less fructosan than those of the earlier cuts.In Part 11 the changes in the amounts of the water-soluble carbohydrates in four perennial grasses during their normal growth-cycle from April to October were described. These grasses passed through the flowering and seed-setting phases, and it was suggested that these physiological changes were probably responsible for the fluctuations jn the content of the major carbohydrate fraction, the fructosan, most of which was present in the stem. The content of free hexoses and sucrose varied with the stage of growth, but there was little difference either between the values for the different species or the values in the two successive years. The value of the free hexoses was low at all times of the season, whereas the sucrose content rose appreciably in May-June.Having thus established the trend of the carbohydrate changes associated with the continuous growth of grasses, we wished to investigate the composition of the soluble carbohydrates in grass such as would be used for grazing dairy cows. The present paper deals with the same four grasses used previously, but in the present experiments they were cut with a motor-mower whenever they had grown to a height of about 8-10 in. I t is realized that this did not closely resemble defoliation by animals on the widely used system of continuous grazing, but it would bear a fair resemblance to the removal of herbage by close-folded animals or in well-managed rotational grazing. ExperimentalThe grass plots used were part of those described in Part I, and consisted of rye-grass (Lolium perenne, strain S23), cocksfoot (Dactylis glomerata, strain sI43), meadow fescue (Festuca pratensis, strain S53) and timothy (Phleum pratense, strain S48) in their first and second harvest years (1951 and 1952). The plots received 2 cwt./acre each of potash (60% K,O) and superphosphate (18% P,O,) in February of each year, and a further I cwt./acre of each fertilizer in June. ' Nitro-Chalk ' (15.5% N) was applied as follows : z cwt./acre in April and 3 cwt./acre after each cut until August, when the amount was reduced to I cwt./acre after each cut. The plots had been divided into two ; one half of each grew on without check (as described in the previous experiment'), but the other half was cut whenever it reached a height of about 8-10 in. The grass was cut between 9 and 10 a.m. with an Allen motor-scythe. I t was considered that the height of the stubble left by this machine, 1-2 in.,...

The intensive production of herbage for crop-drying Part VI. A study of the effect of intensive nitrogen fertilizer treatment on species and strains of grass, grown alone and with white clover

“…Cocksfoot tends to have a lower non-protein nitrogen content than ryegrass (Table 10) and also has a lower content of soluble sugar than other species (Waite & Boyd, 19536). These observations are both in accordance with the view that cocksfoot is particularly efficient in rapidly synthesizing structural material, and may account in part for the rapidity of growth which it normally displays.…”

“…These results suggest that there may be wider differences between species than is generally thought. More detailed evidence of some of these differences is given by Waite & Boyd (19536). The botanical composition of the swards Botanical analyses were carried out by a simplified Point Quadrat method at the end of each season, at least ten sampling frames each of ten each grass and treatment, being means of three replicates for all except treatment 2X, 2Y and 2Z, are too bulky for presentation but are available on application to the authors.…”

Prevalence of Clostridium perfringens in faeces and ileal contents from grass sickness affected horses: Comparisons with 3 control populations

“…Although dietary intake is dependent on the feed provided, it is also influenced in grazing animals by seasonal fluctuations in the relative composition of herbage. Waite and Boyd (1953) demonstrated that the nonstructural carbohydrate content of grasses was greatest in late spring, declined in mid summer and then reached medium levels in early autumn. Similarly, fluctuations in grass protein content also show a seasonal pattern, being highest when the plant is young (spring) and declining at the time of ear emergence (summer) (Green et al .…”

Extraction of Total Available Carbohydrates from Grass and Legume Tissue

“…Grasses native to temperate latitudes, such as timothy and orchardgrass, accunmulate sucrose and fructosan ( 1,4,7,12,13). Extraction of total available carbohydrates has been accomplished by acid hydrolysis (8) or with water (1,14,15) since fructosan is soluble in water. Starch, however, is largely water-insoluble.…”