Leaf protein concentrates were treated in various ways in an attempt to improve their nutritive value, as measured by the “gross protein value” technique with chicks. Washing with hot water improved the value of some lucerne concentrates by removing a water‐soluble toxic factor. No appreciable improvement was obtained by: (a) varying pH of precipitation of curd, (b) different methods of drying the wet curd, or (c) solvent extraction of pigments, waxes, etc. Dried whole juice and alkali‐soluble protein had low nutritive values. The leaf protein concentrates differ considerably in “gross protein value”, but all are inferior to the better animal protein concentrates.

The value of leaf protein concentrates as supplements to cereal diets for chicks has been studied using the ‘gross protein value’ technique. Protein concentrates from different crops have been found to vary widely in nutritive value, but have in all cases been inferior to casein. Concentrates from lucerne contained a factor depressing chick growth, the effect of which was counteracted by adding cholesterol to the diets. This factor was not found in concentrates from Italian ryegrass or white clover. The addition of lysine increased the value of diets containing leaf protein concentrates, possibly because the lysine present in the latter was partly unavailable through low digestibility of the proteins or chemical combination.

The standard method of measuring the digestibility of pasturage involves the daily cutting of fresh herbage from the field for feeding to the experimental animals (1, 2). That the herbage cut may not be representative of that consumed by animals actually grazing has been noted (1, 3, 4), but such feeding trials are likely to be valuable in connexion with work on the relation between composition of faeces and feed intake, and in studying the factors affecting digestibility. However, the method suffers from several disadvantages. Firstly, the labour involved in the daily cutting and sampling of the feeds is considerable, and various errors in sampling are introduced. Secondly, during the ten to fourteen days of the feeding trial, the grass available on the field will increase in maturity, and so will be likely to decrease in digestibility. ' Table 1 gives data from two such feeding experiments conducted during 1947. The crude protein contents of the herbage consumed by the sheep in cages during the successive four-day sub-periods of each experiment are given, and below these is recorded the digestibility of the dry matter eaten during the sub-period (these figures, over such short periods, can only be approximate). Trial Trial 1 2 % CP. % D.M % CP. % D.M eaten dig. eaten dig. Period 1 15.4 73.0 14.65 71.0 Period 2 13.15 68.4 12.95 64.5 Period 3 11.35 60.9 11.2 64.7 TABLE 1. Digestibility data for grass (average of three sheep).It is seen that as both trials progressed, the protein content of the herbage eaten by the caged sheep decreased, this being accompanied by a decrease in the dry matter digestibility of the grass. By taking aliquot samples of each day's feed, and bulking for chemical analysis, an average figure is obtained, but variation in feed quality is obviously undesirable in accurate experiments. This has been considered by Forbes and Garrigus (5) who reduced the feeding period with steers to six days in order to minimise errors due to the changing herbage composition. In the experiments of Sheehy (6) separate plots on a uniform sward were mown on 14 consecutive days, and then after 35 days growth the plots were mown in the same order throu.ghout a further 14 days, and the herbage fed to caged sheep. This method gave herbage of constant composition, but involves conditions of management which are rather artificial.Forbes and Garrigus (5) have also considered the difficulty of feeding the same weight of dry matter to the animals each day. This they overcame by carrying out a rapid moisture determination on the cut herbage each day before weighing the feeds.Ul

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1. The extraction of leaf protein from autumn-grown perennial ryegrass is described.2. The composition, chemical analysis and rate of feeding of two mashes compared in the experiment are given. The same basal cereal mixture was used in each ration, with fish meal added to one and leaf protein and minerals to the other.3. Two groups of three birds were kept on each ration. Nine-month-old Brown Leghorn × Light Sussex pullets, in full lay, were used.4. The birds were given a 6 weeks' preliminary period on a uniform ration to accustom them to the experimental conditions and to ascertain their potential egg production.5. In a 10-week feeding trial no difference occurred in the number of eggs or the total weight of eggs laid by the birds fed on either ration.6. A small loss of body weight occurred in the birds in both treatments.7. Egg-quality determinations indicated that the specific gravity of the eggs was not affected by the differential feeding. Yolk height was greater in eggs from birds fed on the ration containing fish meal. This ration also resulted in a higher number of eggs with rough shells and containing a higher content of foreign bodies.8. The eggs from both treatments had low ‘Yolk-colour indices’, showing that the leaf xanthophylls were not present in quantities in the leaf-protein extract.