The first results are reported of collaborative work carried out, under the aegis of the Agricultural Research Council, at 13 different laboratories to assess different laboratory procedures for the evaluation of quality in protein concentrate feedingstuffs. In all, 130 samples of seven different types of protein concentrate were evaluated by the Gross Protein Value (GPV) procedure as supplements to cereal protein for chicks and in addition Net Protein Utilisation (NPU), with the samples as the sole protein source for rats, was determined for a limited number. Various chemical and microbiological procedures were applied to the samples in the collaborating laboratories. For fish, meat and whale meals the ‘available lysine’ procedure based on the reactivity of ϵ‐amino groups in the lysine units with fluoro‐2,4‐dinitrobenzene correlated best with the GPV results. For cottonseed meals the results of nitrogen solubility tests correlated well with GPV. Microbiological procedures also yielded some useful correlations.

The Gross Protein Value technique, modified in certain particulars, has been used to evaluate 171 samples of protein concentrates, obtained from world-wide sources, and including a number of animal by-products and oilseed meals.The assessments demonstrated that in nearly all tliese classes of concentrate the samples on the market differ widely in nutritive value. The work reported indicates the need for rapid laboratory tests which will predict the value of different protein concentrates and the range of samples should provide useful reference standards for this purpose. IntroductionThe problem of devising rations for non-ruminant farm animals in the United Kingdom in which the prptein is adequate in both quantity and quality, is complicated by the diversity of materials on the market. The bulk of the feed may be composed of one or several cereals providing energy and some protein. To this must be added one or.more concentrates in order to increase the protein content and to provide a sufficiency of essential amino-acids, some of which will be in short supply in the cereals. These protein concentrates include animal byproducts such as meat and bone meal, fish meal, and dried skimmed milk, and vegetable materials such as groundnut meal and soya-bean meal.In practice several concentrates may be used together and at present the choice depends largely upon the availability and prevailing price of materials. For example groundnut meal may be replaced by sunflower seed meal if the economic conditions dictate, and at another time both may be replaced by soya-bean meal. Such manipulation is permissible if the various mixtures are equivalent in nutritive value. In view of the differing amino-acid compositions and energy contents of the various types of protein concentrate this equivalence is unlikely, and the difficulty is surmounted by the inclusion of larger quantities of supplementary protein than necessary, in order to provide a ' margin of safety '. Information on ' replacement values ' for individual concentrates would permit the safety margin to be cut down, thereby reducing the price of the product and also ensuring that these valuable commodities be used to their best advantage. Recognised deficiencies in quality with respect to a particular component of a mixture could be remedied either by increasing its level, or by adding another material capable of complementing the effect of the first.The biological evaluation of even a proportion of the possible combinations of cereals and concentrates would be a formidable task. Further the variation in quality between different specimens of the same material would seriously detract from the usefulness of the results obtained. The value of a mixture of two concentrates fed with a cereal basal ration may well be greater than that of an equivalent quantity of either.l In consequence deductions from evaluations of single concentrates must be made with care. In addition, the value of a particular concentrate will be affected by the cereal components present in the diet. Despi...

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A protein conccntrate made from wheat leaves, and dried b y a commercial process, was tested as a source of supplementary protein i n practical diets for newly-weaned pigs based on a z : I mixture of barley meal and millers' offals. When about 7% of dricd leaf protein concentrate was included in the diet the rate of growth and the efficiency of utilisation of feed by the pigs were as good as when the diet contained 8% of white fish meal, the two diets being roughly equivalent in their contents of total and supplementary protein. When the content of dried leaf protein concentrate was raised t o IO%, or higher, there was no better growth but the efficiency of utilisation of feed was significantly improved. Inclusion of a small amount (4'5%) of dried leaf protein concentrate in a diet otherwise deriving its supplementary protein from groundnut meal, promoted as good growth and as high an efficiency of utilisation of feed as with high levels of leaf protein concentrate.. IntroductionOnly a limited amount of work has been reported on the use of leaf protein concentrates in the practical feeding of pigs and poultry. In some of this work the products used were made during the early stages of development of the process of preparing protein-rich concentrates from leaves, and the results obtained may not be a safe guide to the nutritive value of later products made by more refined methods. In some of the work the material fed was the wet proteinrich curd and the findings might not apply t o dried products.The early products yielded contradictory results in poultry feeding, whether fed as the wet curd or the dried product. When fed in both forms, leaf protein concentrates were found t o be inferior to white fish meal as a source of supplementary protein in the starting diets of chicks.l I t is possible that failure to include in the diet sufficient leaf protein concentrate to provide as much supplementary protein as the white fish meal provided, in the standard diet, might explain part of the observed inferiority. For growing pullets, dried preparations of leaf protein concentrates proved variable as sources of supplementary protein in diets of a practical nature, with a relatively high content of protein.2 The nutritive value of those samples that appeared to be about equal to white fish meal under these conditions, was not examined under more critical conditions, with the amount of protein provided closer to requirements. For the laying bird, the earlier favourable results obtained with an oven-dried leaf protein concentrate3 were not confirmed in more extensive tests subsequently made with a roller-dried product fed, in diets more critical, for egg production, in their content of protein.2Only one test with pigs has been r~p o r t e d ,~ and in this the product used was made by the current Rothamsted process. In this work, leaf protein concentrate, in the wet curd form, proved equal to wliitc fish meal, for growing pigs between about 50 and 1120 lb. liveweight, when fed as a protein supplement in practical diets, and in ...

Seventy-six samples of barley embracing 14 varieties grown under various conditions of nitrogen fertilisation in different locations in the U.K. were examined for nitrogen content and 14 samples were analysed for their total content of amino acids other than tryptophan.Top dressing with nitrogenous fertilisers during growth resulted in the production of grain with a higher nitrogen content as well as an increased overall yield of nitrogen/hectare. The growth locality had a greater effect upon the nitrogen content of the harvested seed than did the application of nitrogen to the growing crop.Lysine content was inversely proportional to crude protein content for barleys containing between 8 and 11 % crude protein and, in consequence, within this range the yield of Iysine/ton of grain was of the same order.