R. E. Evans

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.

Nutrition of the bacon pig XVI. The relative supplemental value of the proteins in extracted soya-bean meal and in white-fish meal

In continuation of our work on the relative supplemental value of animal and vegetable protein concentrates (Woodman & Evans, 1951), a study has been made of the proteins in extracted soya-bean meal. It is probable that vegetable protein concentrates may vary among themselves in nutritive value and that the proteins of ground-nut meal, which were the subject of investigation in our previous experiments, could not for this reason be regarded as representative of vegetable proteins in general. The same basal diet, composed of roughly 2 parts of barley meal and 1 part of fine bran, together with a little lucerne meal and minerals, was again used in the present investigation.

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 composition and digestibility, when fed to pigs and sheep, of potato cossettes and potato meal

Artificially dried potatoes are being marketed in this country at the present time in two grades, known as potato cossettes and potato meal. “Chat” potatoes are first washed in water tanks provided with revolving paddles and are then elevated into a machine that pulps them into pieces about the size of fingers. The resulting cossettes enter the drier directly from the pulper, forming a layer about 4 in deep. The wet material passes on an endless conveyer, consisting of a drying belt of perforated sheet metal, through three zones of temperature. The hot-air current has a temperature of 250–260° F. in the first stage and 180–200° F. in the third. The dried cossettes, which are suitable for feeding to sheep and cattle, may be ground to potato meal for use in the rations of pigs.

Sheep nutrition: I. Measurements of the appetites of sheep on typical winter rations, together with a critical study of the sheep-feeding standards

Feeding trials with sheep, subsisting out-of-doors on typical winter rations of known dry-matter and starch-equivalent content, have been carried out during the winters of 1933–4, 1934–5 and 1935–6. Records have been kept over these periods of the live-weights of the animals and their daily consumption of dry matter and starch equivalent. It has been found that the standards of appetite, in terms of lb. dry matter, proposed by Prof. T. B. Wood are uniformly too high, a result in harmony with the findings of Prof. J. A. S. Watson and co-workers at Oxford. It is suggested that Prof. Woods values should be multiplied throughout by the factor 0·85 in order to obtain reasonable measures of the appetites of sheep at different live-weights. The data from the feeding trials have been used in an attempt to decide between the old and the recently proposed standards for the maintenance starch-equivalent requirement of the 100 lb. sheep, namely, 0·74 and 1·26 lb. of starch equivalent per day. The results point to the reliability of the higher figure, and it is shown that the results of recent work on the energy metabolism of sheep are in harmony with this conclusion. A table embodying a revision of Prof. Woods feeding standards for sheep is included in the paper.

The Value of Degermed Maize Meal (Cooked) in the Nutrition of Swine

The growth-promoting properties of maize, when fed to pigs in conjunction with the proper supplements, have long been recognised. Unfortunately, on account of its detrimental influence on the fat of the pork or bacon, the liberal use of maize in the rations, particularly the finishing rations, of porkers and baconers is to be deprecated. This impairment of the quality of the fat is attributed to the influence of the oil constituent, of which maize contains usually from per cent., compared with but per cent. in barley.

Studies of the Sulphur of Pasture Grass. I. The Cystine Content of Pasture Grass

1. Organic sulphur determinations have been carried out on pasture grass at different stages of maturity. A decrease of about 39 per cent. was found in this constituent when the grass was cut for hay compared with the weekly and fortnightly stages of growth. 2. The application of heavy dressings of inorganic sulphates to a good heavy clay permanent pasture produced an average increase of 8 per cent. in the organic sulphur content. 3. No correlation was found between the organic sulphur and protein content of pasture grass, which suggests that the organic sulphur is present in part, at least, as non-protein sulphur.

The minimum amount of white-fish meal required to supplement the proteins in some vegetable-protein concentrates

It was shown in previous work (Evans, 1958) that a cereal diet supplemented with 7% of white-fish meal supplied around 0·76% of lysine and 0·5% of methionine plus cystine. The addition of more pure l -lysine monochloride or dl -methionine to this animal-protein diet failed to bring about any significant improvement in the rate of growth, efficiency of food conversion or in the nitrogen retention of the pig, in the critical period between weaning and 80 lb. live weight. When the same cereal diet was supplemented by as much as 20% of ex. dec. ground-nut meal, however, the lysine content amounted to only 0·62% but the methionine plus cystine was 0·53%. On adding 0·2% l -lysine plus 0·2% dl -methionine to the 20% ground-nut diet the utilization of the nitrogen in the food was improved and the excretion of nitrogen in the urine was reduced. This finding was confirmed by means of a statistically designed growth trial, the daily rate of live-weight gain, improving from a mean value of 0·86 to 0·98 lb. following the addition of 0·2% of lysine and methionine, respectively, to the diet, the corresponding saving in meal consumption, between 35 and 80 lb. live weight, amounting to 16 lb. One group of ten pigs received a supplement of 0·2% of methionine only, and since it failed to show any improvement in performance over the control group it was concluded that 0·5% of methionine plus cystine must suffice to support satisfactory growth.

Nutrition of the bacon pig XVII. The nutritive value of condensed fish solubles

Investigations have been carried out in this department in recent years with the object of establishing the minimum protein requirements of the bacon pig. The results were recently summarized in this Journal (Woodman & Evans, 1948). The minimum protein standards recorded in that communication are consistent with the attainment of the maximum rate of growth compatible with the net energy content of the diet. The basal foods employed consisted throughout of 2 parts of barley meal and 1 part of middlings (fine bran), together with a little lucerne meal and minerals. Briefly, it was found that such a diet, when supplemented with 7% of white-fish meal, supplied the minimum amount of digestible protein required for the quickest possible rate of growth between weaning and 90 lb. live weight, when the level of feeding was such as is shown in the feeding chart (see Table 7). It was also found unnecessary to include any protein concentrate in the diet beyond 90 lb. live weight to ensure the maximum rate of growth over this later period. The requirements were based on the results of statistically designed growth trials, and were confirmed by nitrogen-balance determinations carried out in metabolism crates. It was found that nitrogen retention was just as favourable on the basal diet supplemented with 7% of white-fish meal as when the protein level was increased by feeding higher amounts offish meal.