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Three experiments were conducted to evaluate the nutritive value of sorghum var. serena known to be a high tannin variety (HTS). In the first experiment 16 female pigs weighing 23.5 kg on average were allotted to 2 dietary treatments; germinated and ungerminated sorghum diets. The experiment lasted for 5 weeks during which time, feed intake and growth rate were measured. Growth rate, feed intake, and feed conversion ratio were not affected by treatment. In a second balance experiment with pigs it was shown that digestibility was not significantly affected by germination. A third experiment was conducted using Wistar male rats to determine true protein digestibility (TD), biological value (BV), net protein utilization (NPU) and digestible energy (DE) of sorghum. BV, NPU and DE were reduced by sprouting. Chemical analyses revealed also that dry matter (DM), ether extract (EE) and ash were reduced after sprouting. The average daily gains obtained from the sorghum diets are comparable to values obtained with other cereal sources. The results indicate that germination is not an effective way of improving pig performance through reduction of tannin levels in serena sorghum.

Piglets weaned at an age of 4 weeks were fed for 28 days with diets having different concentrations of the amino acids lysine, methionine and threonine. A basal diet which was considered to contain the requirement for essential amino acids was fortified with 20% extra of the above mentioned amino acids singly or in combinations. A growth trial with 160 pigs and a balance trial with 32 pigs were performed with 8 diets having different combinations of lysine, methionine and threonine. On the parameters daily gain, feed utilization and N-balance no interaction could be recorded between the three amino acids added to the diets. However, all three parameters responded positively to the lysine fortification while this was not the case when methionine or threonine was added. The extra lysine in the diets improved the biological value 10% while daily gain and feed utilization were raised 8%. Values for digestible amino acids (lysine, methionine, threonine) in relation to digestible energy are presented.

1. Genetic adaptation was investigated in broilers selected for seven generations on a normal (A) or a low (B) protein diet.2. Protein and energy metabolism were studied in males from these selected lines fed on a diet of intermediate protein content.3. All selected birds retained more nitrogen than those studied 10 years previously.4. There was no difference in nitrogen retention between groups, although relative growth rate of group B birds was higher.5. Heat productions relative to gross energy intake were 0.38 (group B) and 045 (group A). Energy retentions relative to gross energy intake were 0.39 (group B) and 0.35 (group A); the difference being primarily due to higher fat retention in group B.6. Using a common maintenance requirement for metabolisable energy, group B utilised metabolisable energy for growth (0.78) better than did group A (0.71).7. At 53 d of age plasma glucose (10%) and insulin (50%) were higher in group B than in group A.

The nutritional value of three pale seeded and one dark seeded variety ofAmaranthus caudatus was studied by chemical analyses and in balance experiments with growing rats. Effects of processing: popping, toasting and flaking were also examined. The pale seeds contained about 14% protein, 10% fat, 2.5% ash, 64% starch and 8% of dietary fibre. The black seeds had a much higher content of fibre (16%). The concentration of essential amino acids were high. Lysine ranged from 5.2–6.0 g/16 g N in the grains, and the limiting amino acids were leucine followed by valine or threonine. The grains contained small amounts of tannin (0.3%) and heat-labile protease inhibitor activity, at levels typical of common cereal grains. Digestibility of protein in the pale seeds was high (87%) and quite unaffected by processing. Protein digestibility of the black seeds was lower, and the digestibility was further reduced by toasting. The biological value of the protein was similar in all products, and very high. The content of minerals varied among varieties and was also affected by processing. Phytate: zinc molar ratios were high in most products, and rats fed the amaranth samples with the lowest zinc contents were in negative zinc balance. In general, femur zinc concentrations were rather low. However, amaranth is an unconventional crop which deserves further attention.

The purpose of this investigation was to study the nutritional value of grain amaranth (Amaranthus caudatus) as a supplement to cereals, and to determine the effect of heat on nutritional quality of cereal/amaranth mixtures. Maize, wheat and low-tannin sorghum blends containing 0%, 10%, 25% and 50% of popped amaranth flour were studied in balance experiments with growing rats. The popped amaranth was very high in lysine (5.19 g/16g N), but lysine was still the first limiting amino acid in the blends. However, amino acid scores were raised significantly by amaranth substitution, and the tryptophan deficiency of maize protein was alleviated by addition of amaranth. True protein digestibility was, in general, not affected by amaranth substitution, but the biological value increased considerably with increasing levels of inclusion. Amaranth substitution also resulted in remarkable increases in weight gain of the rats. The energy digestibility of the different blends was quite similar and there was only little variation in the amount of digestible energy of the mixtures.

Protein, energy and mineral utilization were examined in growing rats fed cooked, dry legume seeds in combination with polished rice. The legumes tested included 3 varieties of common beans, black, white and brown (Phaseolus vulgaris), lentils (Lens esculenta) and peas (Pisum sativum). The rice:legume mixtures (1:1 N ratio) were the only dietary sources of protein, Zn, Fe and Cu. The rice:black bean mixture was also tested at a 4:1 N ratio. Nutrient utilization was studied by balance trials and mineral utilization was further assessed by tissue analyses. True protein digestibility (TD) and energy digestibility of the rice:legume (1:1) mixtures were high. Biological value (BV) varied only little but was lowest in the rice:lentil mixture. The rice:brown bean mixture had the lowest amount of utilizable protein (UP). The (1:1) rice:legume mixtures did not adversely affect Fe status, as measured by liver Fe content and blood hemoglobin and hematocrit, or Cu status, as measured by liver Cu content and plasma ceruloplasmin. However, femur zinc content indicated a sub-optimal Zn status. Increasing the dietary N from rice in combination with black beans resulted in a substantial improvement of BV, NPU and Zn status of the animals but had a negative effect on UP and Fe status of the rats.

Grain yield, chemical composition, protein quality and digestible energy were measured for 18 maize varieties (opaque-2, high oil, waxy hybrids, normal hybrids) cultivated in Yugoslavia. Protein quality assessment was based on amino acid composition, and true protein digestibility, biological value, net protein utilization and utilizable protein as determined in nitrogen balance experiments with rats. The protein concentration in dry matter varied from 8.63–18.81% while the fat concentration varied from 4.45–16.13%. There were only minor differences in ash and crude fibre, while starch and sugar varied inversely to fat and protein concentration. Lysine levels were approximately 30% higher for the opaque-2 varieties compared with normal maize, while leucine levels were about 30% lower. Yields were extremely high for all varieties with the highest value being 10.3 tonnes/ha. Due to the high yields, protein production/ha was high in range of 822–977 kg. This resulted in high yields of amino acids/ha. Protein utilization was very high in the opaque-2 varieties, which had the highest lysine contents. The biological values were close to 80 in these varieties, whereas they were only 60–65 in the normal maize varieties.

Rye, wheat, barley, rice, maize and sorghum were milled into more or less refined fractions, and the content of thiamin, riboflavin, vitamin B6, folate, biotin, niacin and tryptophan were determined. Differences in vitamin content between the different cereal grains were rather small. Refining resulted in marked losses of all vitamins studied. On average, 70%–80% of the vitamins were lost during the milling process. The lowest vitamin content was found in highly refined rice, containing only about 5% of the folate and 10% of the niacin present in brown rice. Maize had a low content of tryptophan, and the concentration was greatly reduced by degerming. For the other cereal grains, milling had only a slight effect on tryptophan concentrations.

Pigeonpea occupies an important place in human nutrition as a source of dietary proteins in several countries. Some of the important factors that affect the protein quality of pigeonpea have been reviewed and summarised in this paper. Among important food legumes, pigeonpea contained the lowest amount of limiting sulphur amino acids, methionine and cystine implicating the importance of these amino acids in protein quality improvement program. Large variation existed in the levels of protease inhibitors of pigeonpea varieties. The concentration of these inhibitors were significantly higher in some of the wild relatives of pigeonpea. Protein digestibility of cooked pigeonpea meal remained low and this could be due to the presence of certain compounds other than trypsin inhibitors. Pigeonpea polyphenolic compounds adversely affected the activity of digestive enzymes and this would affect the protein quality of pigeonpea. The protein quality of pigeonpea was greatly influenced by storage and processing practices.

Brown and milled rices were prepared from rough rice, and the nutritive value of the rices was studied by chemical analyses and in balance experiments with growing rats. The concentration of essential nutrients decreased with the degree of milling, but the energy density of brown and milled rices was similar. In the highly refined white rice the protein content was reduced to 86% and the mineral content to 23% of corresponding levels in brown rice. The zinc concentration was halved. The amino acid composition was rather unaffected by the degree of milling, but the lysine concentration was slightly lower in white rice than in brown rice. Milling was accompanied by an increase in true protein digestibility and a corresponding decrease in biological value. Thus net protein utilization of the different rices was remarkably uniform. A total of 33% of the utilizable protein and 22% of the digestible energy in brown rice was removed during milling.

Low-tannin sorghum was milled into flour with extraction rates between 100 and 64%. The nutritive value of the flours was studied by chemical analyses and in balance experiments with growing rats. The effects of amino acid supplementation was also examined. In general, the content of essential nutrients decreased when the extraction rate was lowered, but the content of fibre, tannins and phytate was also significantly reduced by milling. The digestibility of energy as well as protein was high, but the protein quality was poor, especially in flours of low extraction. Amino acid supplementation improved protein utilization and weight gain considerably. Femur zinc concentration was significantly depressed in the rats fed the amino acid supplemented diets, and sorghum seems to be a poor source of available zinc, in particular when it is highly refined. The poor zinc availability may be attributed to the high content of phytate.

Different grades of maize flour were produced by dry milling of yellow maize. The chemical composition of wholemeal, three semi-sifted flours and degermed maize was determined, and the nutritional value of the flours were investigated in balance experiments with growing rats. Distinct differences in nutrient and fibre content were found. Amino acid composition was significantly different in the milled fractions, and the content of minerals and phytate in the flours was determined by the extent to which the germ was retained. Phytate: zinc molar ratios ranged from 43 to 2. Weight gain of rats was closely correlated to the concentration of lysine (r=0.99) and tryptophan (r=0.97). Weight gain of rats fed degermed maize was reduced to half of that of rats fed wholemeal. True protein digestibility was high, but protein quality varied widely between the different flour fractions. Energy density of the flours was quite similar. Rats fed wholemeal had the highest intake of zinc and the highest apparent zinc absorption and retention but the lowest femur zinc concentration. Factors present in whole maize may interfere with zinc utilization. The results might indicate an interaction between phytate and fibre. Supplementation of wholemeal with lysine and tryptophan increased the biological value of the protein and the weight gain considerably, but apparent absorption and retention of zinc as well as femur zinc concentration were similar in unsupplemented and supplemented rats. The percentage of zinc absorbed from degermed maize flour was high, but degermed maize has a very low content of minerals and is highly deficient in lysine and tryptophan.

Barley was milled into flours with extraction rates between 100 and 69%. The nutritive value of the flours was studied by chemical analyses and in balance trials with growing rats. The concentration of essential nutrients decreased when the extraction rate was lowered. The protein content in the 69% extraction flour was reduced to 82% of that in whole barley. Lysine (g/16 g N) decreased from 3.30 in whole barley to 2.82 in the most refined flour, however, the biological value was not significantly affected by the degree of milling. The content of minerals was reduced to 40% of that in whole barley, but only rats fed refined flours were able to maintain their femur zinc concentration. Factors present in the outer part of the kernel interfere strongly with utilization of zinc; and it appears that phytate is not solely responsible for the adverse effects on zinc utilization. In rats fed whole barley, femur zinc could be maintained and protein utilization improved by zinc supplementation. It could be concluded that unless barley is milled into refined products, or zinc is supplied from external sources, zinc utilization is adversely affected and protein utilization is limited by a poor zinc status.

Variability in oil quality was observed in four groundnut mutants (TG-1, TG-3, TG-14, TG-16) induced by ?-irradiation. The fatty acid composition of the mutants differed from their parent Spanish Improved. All the mutants had lower linoleic and higher oleic acid than the parent Spanish Improved. TG-3 and TG-14 had substantially higher linoleic acid and lower oleic acid as compared with TG-1 and TG-16. Other fatty acids also showed minor variation amongst mutants and Spanish Improved. The ratio of oleic to linoleic acid, which is an index of oil stability, was 2.7 and 3.3 fold respectively in TG-16 and TG-1 as compared with Spanish Improved.

The in vitro and in vivo resistant-starch (measured in growing rats) levels were low in five raw rice cultivars differing in apparent amylose content, and the values were correlated positively with amylose content. Cooked and cooked parboiled rices generally had higher resistant-starch contents than raw rices, particularly those with intermediate gelatinization temperature starches, but waxy rice had very low values. Values for undigestible energy, which is mainly in the form of unfermented energy and undigestible protein, were similar in raw rices, but increased with processing, particularly in the higher-amylose rices. In vivo resistant starch was not correlated significantly with undigestible energy and undigestible protein, but undigestible energy and protein were correlated with each other. Parboiling was calculated to increase the resistant-starch content of cooked rice by not more than 1%. Thus, cultivar differences in cooked-starch digestibility were reflected less in levels of resistant starch than in the rate of starch digestion as indicated by glycaemic and insulin response. Copyright 1993, 1999 Academic Press

Current knowledge of the effects of dietary fibre and associated components on protein digestibility and utilization are discussed. Based on the literature it could be shown that the implications and mechanisms behind the effect of soluble and insoluble dietary fibre on protein digestibility and utilization are quite different. Insoluble dietary fibre will increase faecal bulk and faecal nitrogen excretion is primarily due to and increased excretion of cell wall bound protein. Contrary to this, soluble dietary fibre increase faecal bulk and faecal nitrogen due to an increased excretion of microbial nitrogen. A matter of controversy is the influence of dietary fibre on endogenous nitrogen excretion and factors affecting the losses of nitrogen in this way. It is not known if fibre acts as a secretogogue.

1. Correlated responses in protein and energy metabolism were studied in 2 lines of meat-type chickens selected during 6 generations for improved efficiency of food utilisation (line A) or greater body weight (line B).2. Daily gain was 18% higher in line B but efficiency was 15% better in line A3. Metabolisability (ME/GE) was 0.752 in line A and 0.725 in line B.4. Retained nitrogen as a fraction of nitrogen intake was 0.51 for line A and 0.46 for line B.5. Energy retention as a fraction of metabolisable energy was 0.38 in line A and 0.43 in line B the difference being primarily attributable to greater fat retention in line B.6. Selecting for improved efficiency of food utilisation in meat-type chickens having a growth capacity of 50 to 60 g was very effective and produced a lean bird with higher metabolisability of the diet.

In pot experiments with greatly differing rates of N, P, S, K and Ca, dry matter (DM) yields of leek stems varied from 25 to 164 g/pot. Total-N and NO3-N concentrations varied from 1.18 to 3.56% and from 10 to 1515 ppm in DM, respectively. Both N applications and P and K deficiency greatly increased total-N and NO3-N content. S applications increased total-S content from 0.047 to 0.359% in DM, of which between approximately 100 to 25% were found in methionine+cystine. Total-N/total-S ratios decreased from 57 to 6 with the highest S level. P and K applications increased their respective content in DM two- and threefold. Severe Ca deficiency reduced Ca content from 0.495 to 0.045%. Iron, zinc, manganese and copper contents varied from 33–69, 14–26, 11–34 and 3.1–5.7 ppm in DM, respectively. Increasing N contents, whether due to N applications or P or K deficiency, decreased the content of all essential and some other amino acids in crude protein. Both S and severe P deficiency had a pronounced negative effect on amino acid composition and chemical score. Only glutamic acid (glutamine) and arginine were increased by increasing N contents. However, expressed as g/kg DM the concentrations of all amino acids were positively correlated with protein content. S and P deficiency reduced total dietary fibre (TDF) content of DM from 28.3 to 18.6% and 17.4%, respectively, of which between 53 and 60% were insoluble dietary fibre (IDF). Digestible energy (DE) was positively correlated with protein content (r=0.90**). In N-balance trials with rats, increasing protein concentrations (50% of total protein given as casein and supplemented with 1% methionine) raised the true digestibility (TD) of the protein from 44 to 72%. The biological value (BV) of protein was generally high, with a mean of 91.7 N deficiency tended to increase and S deficiency tended to decrease the BV.

Chemical analyses and feeding experiments using rats were conducted to evaluate the nutritive value of winged bean and other legumes (soyabean, green gram, bambarra nuts, pigeon peas, field beans, cow peas) sources grown in Tanzania. Proximate analyses showed that the composition of winged bean was similar to soyabean, while the composition of the other legumes differed considerably. This was also the case for antinutritional constituents and minerals. As to the amino acid composition, the lysine level was high with the highest value in winged bean (7.5 g/16 g N). However, the concentration of methionine and cystine was low which limits their protein quality. Another important amino acid, threonine, was generally high, especially in winged bean (4.3 g/16 g N). With exception of field bean, true protein digestibility was above 80%, soyabean having the highest value (90.7%). The biological value was also highest in soyabean (76.1%) followed by winged bean (69.9%). Utilizable protein was high in soyabean (28.8%) and somewhat lower in winged bean (23.4%). Energy digestibility was around 80%, soyabean having the highest value of 85.8%. The study findings support the idea that winged bean is a good alternative plant protein source in Tanzania.

Crisphead lettuce was cultivated under different growth conditions. Sixteen batches differed in time of planting (early and late), total nitrogen supply (200 kg N/ha, 150 kg N/ha, 100 kg N/ha, 50 kg N/ha) and time of harvest (early and late). Based on chemical analysis and balance studies on rats the nutritive value of each 16 batches was determined. The protein content increased progressively from 16.00 to 19.88% with fertilization level. This increase in protein caused a significant drop in essential amino acids (g/16 g N) demonstrating a lower biological value of this protein. Early planting or early harvest resulted in a higher protein content than in lettuce of late planting or late harvest. Total dietary fibre content was approximately 25% of DM — and this value was not much influenced by the different growth conditions. Soluble dietary fibre was approximately 20–25% of total dietary fibre. Due to the high fibre content, energy digestibility was relatively low. The contents of Cd and Pb were below what is considered as ‘acceptable’ levels.

In pot experiments with greatly differing rates of N, P, K, and S, and 3 levels of water, dry matter (DM) yields of tubers varied from 28 to 454 g/pot. Especially P-, K- and S-deficiency reduced the starch content of boiled potatoes, from P from 74 to 59% in DM. S-deficiency increased soluble, insoluble and total digestible fibre (TDF) from about 9 to 12.4% TDF in DM of boiled potatoes. Lignin content of fresh potato DM was increased from 0.7 to 2.0 and from 0.8 to 3.7% by P- and K-deficiency. P-deficiency considerably increased arabinose, galactose, and uronic acid, and decreased glucose content. N-application and P-, K- and S-deficiency increased total- and NO3-N concentrations which varied from 1.32 to 3.67% and from 17 to 400 ppm in DM. Water stress slightly decreased total-N content. Increasing N in DM, due to high N-rates or P- or K-deficiency, decreased concentrations in crude protein (CP) of all essential amino acids, whereas aspartic acid (asparagine) increased. S-deficiency caused particularly strong decreases in concentrations of essential amino acids from 1.28 to 0.49, 1.62 to 1.10, 5.24 to 3.68, and 5.59 to 2.57 g/16 g N of cystine, methionine, lysine and leucine, respectively. Glutamic acid (glutamine) content was increased from 15.7 to 27.6 g/16 g N by S-deficiency. Expressed as g amino acid/kg DM, all amino acid concentrations increased with increasing % N in DM. In N-balance trials with rats, increasing crude protein concentrations in DM of boiled potatoes increased the true digestibility (TD) of the protein from 72 to 90 but decreased the biological value (BV) from 89 to 65. S-deficiency caused a further reduction of the BV to 45. Excluding S-deficiency treatments, linear regression equations between CP concentrations and BV and TD gave correlation coefficients r of -0.94*** and 0.82***, respectively. There was close agreement between changes of BV and concentrations of first limiting amino acids (chemical score), with r=0.96***.

Nutrient composition of eight commonly consumed spices of South India was analysed. Spices analysed were red chillies (Capsicum annum), black pepper (Piper nigrum), coriander seeds (Coriandrum sativum), cumin seeds (Cuminum cyminum), garlic (Allium sativum), asafoetida (Ferula foetida), dry ginger (Zingiber officinale) and ajowan (Carum copticum). The nutrients analysed were proximate principles, minerals, starch, sugars, dietary fibre components, tannins, phytic acid, enzyme inhibitors and amino acids. Dry ginger, ajowan and asafoetida had high calcium (1.0–1.5%) and iron (54–62 mg/100 g) levels. The tannin content of spices was also high (0.9–1.3% DM). Dietary fibre ranged from 14–53%. Spices had appreciable amounts of essential amino acids like lysine and threonine. A survey revealed the average per capita consumption of spices to be 9.54 g and at that level, the nutrient contribution from spices ranged from 1.2 to 7.9% of an average adult Indian male's requirement for different nutrients.

The chemical composition of different varieties of field beans (Vicia faba L.), cowpeas (Vigna unguiculata), groundnuts (Voandzeia subterranea), and sorghum (Sorghum vulgare) were determined. Nutrients analysed in these materials included amino acids, starch, sugar, fibre, minerals and antinutritional factors. All the materials were further tested in balance trials with rats; true protein digestibility (TD), biological value (BV), net protein utilization (NPU) and digestible energy (DE) were evaluated. Based on the chemical analyses as well as on the biological data, the nutritive value of plant materials between species as well as between varieties within species differed considerably. Therefore, more quality evaluation studies along with plant breeding programmes are needed to select the most promising varieties from the nutritional point of view.

Genetically dependent 20 to 30 percent increase in lysine per 16 grams of nitrogen results in improved nutritional values in feeding trials with mice and rats. The recessive gene was selected from the World Barley Collection. Other amino acids are also influenced by the gene. Protein content segregates independently of the changed amino acid pattern. The gene putatively influences the matrix proteins, which characteristically adhere to the starch grains in meal preparations. The morphological character permits rapid microscopic screening of single seeds without affecting viability. Low yield is considerably improved by crossing and selection.