H. E. Woodman

Nutritive value of pasture: I. Seasonal variations in the productivity, botanical and chemical composition, and nutritive value of medium pasturage on a light sandy soil

An account has been given of an investigation into the seasonal changes in the productivity, botanical and chemical composition, and nutritive value of pasture grass, the work constituting the initial stage of a comprehensive study of the nutritive properties of different types of pasture. The pasture on which the work was carried out was situated on a light sandy soil of low water-retaining capacity; the pasturage was of medium quality. Grazing was imitated by the daily use of a motor-mowing machine, the system of cutting being such as to ensure the whole plot being cut over once per week. The season was divided into ten periods, each period corresponding with the duration of a digestion trial carried out on two wether sheep. The main feature of the weather conditions during the season was the extremely low rainfall during the period from early June to mid-July. The pasture plot results were compared with corresponding results obtained from contiguous plots which were allowed to grow for hay, and from which, after removal of hay, several successive aftermath cuts were taken. The main findings of the investigation are summarised below: Seasonal changes in the botanical composition of the herbage . Although precise and systematic botanical analyses of the herbage of the pasture were not carried out, yet careful surveys made at an early and a late date in the season, together with general observations made during the whole course of the experiment, enabled interesting conclusions to be drawn in respect of the seasonal activity and persistency of the different species of grasses in the sward. During the spring season, Bromus mollis, Lolium perenne, Poa annua and Poa trivialis accounted for almost 80 per cent, of the herbage.

The mucous secretion of the cervix of the cow

The secretions of the cervix are of interest because of the changes that occur in them during the oestrous cycle and during pregnancy. It is probable that these changes have an efEect in assisting or hindering the ascent of the spermatozoa to the Fallopian tubes after their deposition in the vagina.

Nutritive Value of Pasture. VII. The Influence of the Intensity of Grazing on the Yield, Composition and Nutritive Value of Pasture Herbage (Part III).

The main conclusions from the present investigation, which was undertaken in order to obtain an insight into the consequences of the adoption of a 5-weekly rotational close-grazing system, may be summarized as follows: The lengthening of the interval between successive cuts from a month to 5 weeks leads to a definite, though not very serious, reduction in the digestibility of the herbage. This reduction is most noticeable during the flush period of growth, and the constituent most affected is the crude protein. During the fore-flush and post-flush periods, it appears to be immaterial, from the standpoint of digestibility, whether a system of monthly or 5-weekly cutting is adopted. The falling off in digestibility is not connected with the onset of lignification in the herbage, since the digestion coefficient of the fibrous constituent remains high throughout the season, and it may be concluded that, during a season of favourable rainfall , it is possible by cutting (or close-grazing) at intervals of 5 weeks, to prevent the herbage from becoming lignified and of greatly reduced digestibility. The possibility, however, during seasons of a droughty character , of a premature onset of lignification under a system of cutting (or close-grazing) at 5-weekly intervals is discussed.

Digestion trials with swine: II. Comparative determinations of the digestibility of dry-fed maize, soaked maize, cooked maize and flaked maize

In Table XII is given a summary of the mean digestion coefficients obtained in the foregoing maize feeding experiments. The figures in Table XII bring out very clearly the effect of preliminary treatment on the digestibility of maize. An inspection of the dry matter digestion coefficients reveals the fact that maize meal possesses the lowest digestibility when fed in the dry condition, a higher value when fed after thorough soaking in water and a higher value still when first submitted to cooking. These facts are in accordance with anticipation; the surprising feature of the results, however, lies in the discovery of the inappreciable extent to which the maize digestibility is raised by soaking or cooking. A relatively low degree of digestibility might justifiably have been anticipated for raw unsoaked maize, since the hard flinty nature of the grain, even after crushing, might render it liable to be excreted in appreciable amount into the faeces without having been much affected by digestive enzymes. This proved by no means to be the case. The effect of thoroughly soaking the grain prior to feeding was merely to raise the digestibility of the maize by 1 per cent, (from 85·9 per cent, to 86·9 per cent.), whilst even efficient cooking only brought about a rise in digestibility from 85·9 to 88·1 per cent., although, as will be noted by reference to an earlier part of this communication, the conditions of the trial were weighted in favour of the cooked meal by using fine meal for cooking and crushed maize for dry-feeding.

A chemical study of the development of the wheat grain

The connection which has been shown to exist between the strength of wheat flour and the chemical individuality of the glutenine fraction of the wheat protein (Woodman, 1922) (1) led the writers to institute an enquiry into the manner in which the individual wheat proteins are developed and stored during the progress of the grain from the early stages after flowering to ripeness. The immediate object of the investigation was to secure information in regard to the stages at which the different proteins made their appearance in the grain and to determine at what point the character of the grain contents was such as to enable a tenacious gluten to be obtained by grinding up the kernels with successive quantities of dilute NaCl solution. It was also intended to follow the rate of alteration of the amounts of the several proteins during the growth of the grain and to attempt to elucidate as far as possible the relationships which exist between the simple and complex forms of nitrogen at the various stages.

The mechanism of cellulose digestion in the ruminant organism

During the carrying out of the series of researches which led to the formulation of the well-known expression for calculating the starch equivalent of a feeding stuff, Kellner(1) was led to investigate the value of crude fibre in the fattening ration of oxen. For this purpose he used material which had resulted from the boiling of rye straw with an alkaline solution under pressure, the object of this treatment being to free the cellulose of the straw from incrusting substances. This fibre-rich preparation was added to a basal ration which was slightly in excess of maintenance requirements. The result produced by the addition to the basal ration of the digestible matter derived from the fibre of the treated straw was found by Kellner to be equal to that produced by the addition of an equal weight of pure starch. The conclusion was therefore warranted that the digestion products of cellulose in the ruminant organism are equal, for purposes of fat formation in the body, to those derived from the digestion of starch. This finding is given practical expression in Kellner1s formula for calculating the starch value of a feeding stuff, an equal value being attached to digestible fibre and digestible carbohydrate. It is clear that any theory which is put forward to explain the breakdown of cellulose in the ruminant tract must be compatible with the experimentally demonstrated fact that the products of such digestion of a given weight of digestible fibre are equal in nutritive value to the products derived from the digestion of the same weight of starch.

The nutritive value of fodder cellulose from wheat straw. II. The utilization of cellulose by growing and fattening pigs

The fodder cellulose used in this investigation was prepared from wheat straw by the factory process described in the preceding communication. It was dried and milled, so that the resultant material was light and fluffy in character, with the fibres well frayed. This was considered to be important, since the physical state of the cellulose might exert a considerable influence on the ability of the intestinal bacteria to bring about its fermentation and breakdown. It was shown in the preceding paper that the fodder cellulose, on the basis of dry matter, contains 79·8% of crude fibre, of 85·1% digestibility, and 69·2% of ‘total digestible nutrients’. The present feeding trial has demonstrated that the figure for ‘total digestible nutrients’ obtained from the results of the pig digestion trial is a true measure of the productive value of the fodder cellulose for growth and fattening in bacon pigs, provided that the product is fed in a finely divided condition and in intimate admixture with the meal forming the rest of the ration.

Nutritive value of lucerne. II. Investigations into the influence of systematic cutting at three different stages of growth on the yield, composition and nutritive value of lucerne

The present communication is the second contribution to the study of the nutritive characters of the lucerne crop. It deals with investigations that are the outcome of certain preliminary trials carried out in the 1932 season and reported on in an earlier communication(1). The primary object of the present trials was to investigate the composition, digestibility and nutritive value of the first, second and third growths of lucerne under conditions of systematic cutting at the stages of (1) bud and (2) flower. A determination of the digestibility and nutritive value of lucerne in its pre-budding stage of growth was also made. In addition, account has been kept of the effect of cutting lucerne systematically at certain definite stages of growth, namely, pre-budding, budding and flowering, on the yields per acre of dry matter, starch equivalent and digestible protein, and on the health and vigour of the crop.

Nutritive value of Lucerne: IV. The Leaf-Stem Ratio.

In this paper are brought together a number of data concerning the ratio of the amount of leaf to stem in the lucerne crop, at different stages of growth, and the separate composition of the leafy and stemmy fractions. It is shown that the proportion of leaf falls off as the crop advances in maturity, and that the rate of decrease of leafiness is greater before budding than during the period from the beginning of budding to early flower. The changes in the leaf-stem ratio largely account for the fall in protein content, the rise in fibre content and the running-off in digestibility and feeding value that take place as the crop passes through the successive stages of growth up to flowering.

The mechanism of cellulose digestion in the ruminant organism: II. The transformation of cellulose into glucose by the agency of cellulose-splitting bacteria

An attempt was made in a recent communication (1) to propound a theory in connection with the digestion of cellulose in the ruminant organism which should be compatible with Kellners findings as to the value of digestible fibre in the fattening of ruminants. It was shown that the generally accepted theory, that cellulose is digested by bacterial agency in the rumen with the production of organic acids and gaseous products, such as methane, hydrogen and carbon dioxide, failed entirely to account for the equal values of digestible fibre and starch for fat production in the ruminant animal. This could only be explained by assuming that glucose (or some other sugar capable of hydrolysis to glucose) was formed as a primary product of the action of bacteria on cellulose, and that, as with digestible carbohydrates originally present in the food, only about 8 per cent, of the sugar so formed underwent further bacterial breakdown into organic acids and gases, the remainder being available for absorption into the organism in the form of glucose. On this assumption, it would follow that every gram of fibre so digested would yield to the organism as much glucose as would a gram of starch, and in this way Kellners practical finding would be capable of explanation.