The gross composition and amino acid content of the proteins of barley, corn, rye and wheat grains were determined. Leaf protein Concentrates ( L P C ) were produced @om the green matter of clover, lucerne, barley and ryegrass using standard methods and analysed as for the cereal grains. Each cereal was mixed with each concentrate at a protein ratio of 2:1, respectively. The chemical score (CS) and essential amino acid index (EAAI) of the cereals, the protein concentrates and their mixtures were calculated. The biological value (BV) and true digestibility ( T D ) of all proteins were determined on rats using the Thomas-Mitchell balance method.LPC proteins contained more lysine (4.6-6.0 %)but less cystine than cereal proteins (2-8-3-8 and 2-3-27 g per 16 g N, respectively). The CS and BV of LPC proteins were low (30-40 and 44-58, respectively) because of the low cystine content. Mixing cereals with LPC improved the CS, EAAI and BV of their proteins. The BV of the protein mixtures was in almost every case higher than that of either protein alone, but the digestibility of the cereal proteins was reduced as a result of admixture with LPC, especially with clover LPC.
An experiment lasting 73 days was carried out on 40 Black-and-White Lowland 7-day-old calves divided into 5 groups of 8. The animals received 8 kg of whole milk daily for 5 weeks, 6 kg in the 6th and 3 kg in 7th week with free access to concentrate mixture and meadow hay. After 7 weeks of the experiment the calves were fed only concentrate to appetite and 0.3-0.4 kg of meadow hay. This basic control diet was supplemented with wort without yeast and in the experimental groups with liquid cultures of the yeast, Saccharomyces cerevisiae 1026 or Saccharomyces carlsbergensis of the brewery strain SK-1, BS-Bratislava or wine strain T-81. All strains of yeast significantly stimulated amylolytic and proteolytic activity of the digesta in the duodenum, small intestine and ileum but not in the abomasum. Body weight gains of calves fed diets supplemented with SK-1 and B-Bratislava yeast were higher than in control or in groups supplemented with the other two yeast strains.
The experiment was carried out on 12 Black-and -White Lowland bulls with an average body weight of 400 + 50 kg divided into 4 groups and fed concentrates and meadow hay according to the INRA system. After 2 months of adaptation, the level of metabolites in the rumen was determined and the diet for the respective groups was supplemented with yeast cultures: Saccharomyces cerevisiae 1026, Saccharomyces carlsbergensis brewery strains SK-1, BS-Bratislava or wine strain T-81. All yeast supplements caused changes in yeast cell density, protozoa number, pH, ammonia concen tration and VFA proportion in the rumen of bulls. The greatest growth ability and largest effect on fermentation in the rumen was demonstrated by the brewery strains, Saccharomyces carlsbergensis and Saccharomyces cerevisiae 1026.
I. The concentration of 2-aminoethylphosphonic acid (AEP) in 96 h cultures of Tetrahymenapyriforrnis W was studied in order to apply it as an indicator in the assay of the relative nutritive value (RNV; protozoa population with test protein: protozoa population with whole-egg powder) of protein. Foodstuffs and food mixtures of different protein contents and qualities were used as test samples.2. RNV values based on AEP determination (RNVAxp) were compared with corresponding values calculated from protozoa counts (RNV,,), as well as with biological value (BV) and net protein utilization (NPU) of the same proteins assayed on rats.3. Both for foodstuffs and food mixtures highly significant correlations were found between RNVAEp and RNV,,, RNVAE~ and both BV and NPU, and RNV,, and both BV and NPU.4. AEP content in the protozoal suspension was preferred to cell count as a measure of growth response, since it took into account large differences in cell dimensions that were observed between cultures grown with different test proteins.The method for the evaluation of protein quality using the protozoon Tetrahymena pyriformis W (Fernell & Rosen, 1956) as modified by Stott, Smith & Rosen (1963) involves the determination of the number of protozoa organisms after incubation for 4 d in a medium containing the protein to be evaluated. The total number of protozoa cannot be measured turbidimetrically because many foodstuffs are insoluble and coloured.Total protozoa count, estimated using a haemocytometer, has often been made (Fernell & Rosen, 1956; Teunisson, 1961;Rosen, Stott & Smith, 1962;Stott et al. 1963; Baum & Haenel, 1965;Rslle & Eggum, 1971) but such a procedure is laborious and time-consuming (Teunisson, 1971 ;Shorrock & Ford, 1973). For many years, therefore, studies have been made of the potential use of other methods for protozoal population density determination.Teunisson (1971) proposed a method for counting the cells electronically with a Coulter Counter, after separating T. pyriformis W cells from food particles. Attempts to apply acidity determination (Rockland & Dunn, 1949) or a colorimetric method (Anderson & Williams, 1951; Viswanatha & Liener, 1955; Bergner, Munchow & Koch, 1968) in the measurement of growth responses gave poor results.Methods based on extinction measurements have been applied to alkaline extracts of soluble proteins (VoiiSek & Leitgeb, 1973) and to high-protein meals after treatment with papain (Shorrock & Ford, 1973), but they are not widely applicable.Shepherd, Taylor 84 JULITA M A C I E J E W I C Z -R Y S / AND ANNA M . ANTONIEWICZ foodstuffs and food mixtures, estimated both from protozoa counts in a haemocytometer and from AEP content. The results were also compared with biological value (BV) and net protein utilization (NPU) results determined with rats. MATERIALS A N D METHODS MaterialsThe foodstuffs tested were chosen to illustrate differences in quality within and between different protein sources. The samples comprised: fish meals (FM26, FM33, FM45, FM58), blood meals (...
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