Nutrient contents,rumen protein degradability and antinutritional factors in some colour- and white-flowering cultivars of Vicia faba beans

Six colour-flowering (Scirocco, Alfred, Carola, Condor, Tina and Herz Freya) and six white-flowering (Caspar, Albatros, Gloria, Tyrol, Vasco and Cresta) cultivars of Vicia faba were studied. The crude protein contents of colour- and white-flowering cultivars were 267±13·6 and 283±18·8 g kg⁻¹, respectively, which did not differ significantly at P<0·05. The levels of lipids, crude fibre, starch and ash varied from 14 to 22 g kg⁻¹, 88 to 143 g kg⁻¹, 407 to 485 g kg⁻¹ and 32 to 42 g kg⁻¹, respectively. The calculated organic matter digestibility (OMD) and metabolisable energy (ME) of the white-flowering cultivars were significantly higher (P<0·001) than those of the colour-flowering cultivars (OMD: 889·1±26·6 g kg⁻¹ vs 797·5±17·1 g kg⁻¹; ME: 13·97±0·49 vs 12·30±0·34 MJ kg⁻¹). In all cultivars, sulphur amino acids were lower than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2–5-year-old child. The in vitro rumen nitrogen degradability of colour-flowering cultivars was significantly lower (P<0·01) compared to that of white-flowering cultivars (71·4±9·3% vs 88·0±11·1%). Amongst colour-flowering varieties, the contents of total phenols (TP), tannins (T) and condensed tannins (CT) were highest in Alfred (28·3, 21·0 and 35·4 g kg⁻¹, respectively). The contents of TP and T were similar (about 15 and 10 g kg⁻¹, respectively) in Carola, Tina and Herz Freya, and the CT were in the order: Condor>Herz Freya>Carola. The CT were not detected in white-flowering varieties, T were virtually absent and TP were extremely low (4·0–4·9 g kg⁻¹). The activities of other antinutritional factors (white- and colour-flowering cultivars, respectively: trypsin inhibitor activity 3·05±0·34 and 1·85±0·09 mg trypsin inhibited g⁻¹; lectin 27·2±9·4 and 27·1±5·1 mg ml⁻¹ assay medium producing haemagglutination; phytate 15·0±2·7 and 16·6±2·3 g kg⁻¹) were very low. A strong negative correlation (r=-0·92, P<0·001) between tannins and in vitro rumen protein degradability was observed which suggested that tannins have adverse effect on protein degradability. Similarly negative correlations between tannin levels and metabolisable energy (r=-0·89; P<0·001) and organic matter digestibility (r=-0·89; P<0·001) were observed. The correlation coefficient between trypsin inhibitor activity and tannins was negative and highly significant (r=-0·88, P<0·001), whereas between tannins and saponins it was significantly positive (r=0·96, P<0·001). ©1997 SCI     

Dietary fibre content of thirteen apple cultivars

Fibre composition of the following 13 apple cultivars was studied: ‘Cortland’, ‘Empire’, ‘Fuji’, ‘Golden Delicious’, ‘Gala’, ‘Granny Smith’, ‘Jonagold’, ‘Mutsu’, ‘McIntosh’, ‘Delicious’, ‘Rome’, ‘Stayman’ and ‘York’. Fruit samples from each of these cultivars were analysed for non-starch cell wall materials (NSCWM) and non-starch polysaccharides (NSP). NSCWM was further fractionated into soluble and insoluble fibre fractions. Both NSCWM and NSP content were found to be significantly influenced by cultivar. NSCWM content ranged from 19·1 g kg⁻¹ apple flesh in ‘Fuji’ to 36·2 g kg⁻¹ in ‘York’. Mean(±SD) NSCWM content of all the cultivars was 23·1±4·5 g kg⁻¹. NSP content of apple flesh ranged from 13·8 g kg⁻¹ in ‘McIntosh’ to 28·7 g kg⁻¹ in ‘York’ with the overall mean for all cultivars being 17·9±4·2 g kg⁻¹. Relative amount of monosaccharides found in the hydrolysates of apple fibre also varied among cultivars. The greatest difference was observed in galactose content. ©1997 SCI     

In vitro protein digestibility and mineral availability of green beans (Phaseolus vulgarisL) as influenced by variety and pod size

Three varieties of green beans (Cleo, Strike and Sentry) were harvested and sorted into four fractions according to pod size (diameter <7 mm; 7–8·5 mm; 8·6–10 mm and >10 mm). Ash content and dietary fibre increased significantly as pod size increased mainly in Cleo and Strike beans. Strike showed the highest fibre content (378·0 g kg⁻¹) but the lowest carbohydrate (364·6 g kg⁻¹) and ash (68·4 g kg⁻¹) values. Mean values for Fe and Mg content were higher in Cleo beans (70·9 and 27·1 mg kg⁻¹, respectively), Zn, Cu and Mg were higher in Strike beans (48·7 mg kg⁻¹, 22·4 mg kg⁻¹ and 3·15 g kg⁻¹, respectively) while Na and Ca values were maximum in Sentry (459·1 mg kg⁻¹ and 7·11 g kg⁻¹, respectively). Trypsin inhibitor was negatively related to in vitro protein digestibility but no relationship was found between this last parameter and phytic acid content. This antinutrient, together with dietary fibre, and a negative influence on in vitro mineral dialysability of green beans. © 1998 SCI     

The choline content of feed ingredients and mixed feeds determined by an enzymatic assay

A recently developed procedure for the determination of choline in ingredients and feeds was utilised to establish the levels and the variability of choline in a series of ingredients and to compare the analysed and calculated choline values of mixed feeds. The concentrations of choline in samples of maize (7), canola meal (3), wheat middlings (1) and dehydrated bakery product (1) were, respectively, 1·55±0·18, 7·59±0·08, 2·35 and 2·39 g kg⁻¹, all higher than ingredient composition table values. Choline contents lower than table values were found in samples of poultry by-products (7) and meat and bone meal (6): 2·18±0·87 and 1·08±0·29 g kg⁻¹, respectively. The average choline concentration found in samples of dehulled soybean meal (7) was 2·73±0·18 g kg⁻¹, similar to table values. The choline in samples of poultry fat (2) averaged 0·48±0·02 g kg⁻¹. Significant correlations between the concentrations of choline and of some components of the proximate analysis were found. The analysed choline concentrations in mixed feeds were only 1·4% lower than the calculated levels based on the ingredient analyses. The procedure was adequate for choline determination in ingredients or mixed feeds. The high variability in the choline content of some ingredients may require analysis for proper feed formulation. © 1998 Society of Chemical Industry.     

Response of pancreatic secretions to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of soybean trypsin inhibitors (SBTI) on exocrine pancreatic secretions in growing pigs. Six barrows with an average initial body weight (BW) of 27·1±1·4 kg were fitted with permanent pancreatic re-entrant cannulas and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g kg⁻¹ crude protein from either Nutrisoy (food grade defatted soy flour) or autoclaved Nutrisoy. The concentrations of SBTI in Nutrisoy and autoclaved Nutrisoy diets were 13·4 and 3·0 g kg⁻¹, respectively. The experiment consisted of two periods of 9 days each. The average BW at the start of the first and second experimental periods was 33·5±2·7 and 37·2±3·7 kg, respectively. The average BW at the conclusion of the experiment was 41·8±3·9 kg. The volume of pancreatic secretion was higher (P<0·01) when the Nutrisoy, as opposed to the autoclaved Nutrisoy diet was fed (3804 vs 2634 ml (24 h)⁻¹). The concen-tration of nitrogen and protein and specific activities (units litre⁻¹) of amylase, chymotrypsin and trypsin were lower (P<0·05) in pancreatic juice of pigs fed the Nutrisoy diet. There were no differences (P>0·05) in the total secretions of nitrogen (g (24 h)⁻¹) and total activities (units (24 h)⁻¹) of amylase, lipase, chymotrypsin and trypsin in pancreatic juice of pigs fed the Nutrisoy and autoclaved Nutrisoy diets. However, the total secretion of protein was slightly higher (25·7 vs 22·8 g (24 h)⁻¹; P<0·05) in pancreatic juice of pigs fed the autoclaved Nutrisoy diet, which corresponded with the increase in the secretion of protein-bound amino acids. There was also an increase in the total secretion of free amino acids in pancreatic juice. These studies show no effect of SBTI on the total enzyme activities in pancreatic juice of growing pigs. © 1998 SCI.     

Chemical characterisation and ruminal nutrient degradability of hulled and hull-less oats

The objectives of this study were to determine the chemical and ruminal nutrient degradability characteristics of two hulled (Calibre and AC Mustang) and one hull-less (AC Belmont) oat varieties. Ruminal nutrient degradability characteristics of the oat varieties were determined relative to barley using one ruminally fistulated cow. Neutral (NDF) and acid (ADF) detergent fibre levels were higher (P < 0·05) in hulled than hull-less oats. Hulled AC Mustang had higher (P < 0·05) NDF and ADF content than hulled Calibre. Starch content was higher (P < 0·05) in AC Belmont (590 g kg⁻¹) than Calibre (457 g kg⁻¹) and was higher in Calibre than AC Mustang (415 g kg⁻¹). Crude protein was higher (P < 0·05) in hull-less than hulled oat. Both hulled varieties had similar CP content (average 124 g kg⁻¹). Estimated digestible energy value was highest (P < 0·05) for AC Belmont (16·94 MJ kg⁻¹), intermediate for Calibre (14·18 MJ kg⁻¹) and lowest for AC Mustang (13·34 MJ kg⁻¹). Ruminal dry matter and NDF degradability were higher (P < 0·05) in hull-less than barley and was higher in barley than hulled oats. Ruminal starch degradability exceeded 900 g kg⁻¹ for all tested feeds and had the order AC Belmont = barley > Calibre = AC Mustang. It was concluded that oat varieties used in this study varied considerably in their chemical composition and ruminal degradability. When compared with barley, hulled oats had lower while hull-less oats had higher ruminal degradability. © 1998 SCI.     

Study of the nutritional value of black cumin seeds (Nigella sativaL)

The nutritional value of five samples of black cumin seeds from five different sources available in the local market were studied. The average values of the proximate analysis on dry matter basis were 216 g kg⁻¹ for crude protein, 406 g fat, 45 g ash, 84 g crude fibre and 249 g of nitrogen-free extract, whereas moisture content was 38 g kg⁻¹. The mineral and vitamin analyses showed that black cumin seeds contained iron, (105 mg kg⁻¹) copper (18 mg), zinc (60 mg) phosphorus (527 mg), calcium (1860 mg), thiamin (15·4 mg), niacin (57 mg), pyridoxine (5·0 mg) and folic acid (160 μg). The protein quality of black cumin seeds was evaluated using net protein utilisation (NPU), protein efficiency ratio (PER) and net dietary protein energy percent (NDPE %) for two samples imported from Syria and Turkey, while PER was determined for the Syrian sample only. The results indicated that the NPU standardised of Turkish black cumin seeds was significantly higher than that of Syrian type (P<0·05). The mean results (±SD) were 54·6±2·72 for the Syrian type and 63·1±3·74 for the Turkish type. The NDPE% mean results (±SD) were 5·3±0·79 and 5·6±0·26 for the Syrian and the Turkish samples, respectively. The PER adjusted value for the Syrian samples was 1·9. The results of protein quality evaluation and those of the nutrient composition suggest that black cumin is of relatively good nutritional value. © 1998 SCI.     

Determination of Chlorogenic Acids with Lactones in Roasted Coffee

An HPLC method has been developed which allowed the determination of mono- and dicaffeoylquinic acids (CQA and di-CQA), corresponding lactones (CQL) and feruloylquinic acids (FQA) in roasted coffee within one chromatographic run. The elution order was verified by isolation of the individual compounds by preparative HPLC, chromatography of the fractions on the analytical HPLC system, NMR spectroscopy and thermospray LC-MS. At least 15 additional minor compounds had the spectra of hydroxycinnamic acids, some of them only occurring in roasted coffee. Caffeoyltryptophan, which has been identified some time ago by another working group could also be separated with this system. The average contents in commercial roasted coffee samples (n=12) were: 3-CQA, 5·0 g kg⁻¹; 4-CQA, 6·2 g kg⁻¹; 5-CQA, 11·4 g kg⁻¹; 4-FQA, 0·7 g kg⁻¹; 5-FQA, 1·4 g kg⁻¹; 3-CQL, 2·1 g kg⁻¹; 4-CQL, 1·0 g kg⁻¹; 3,4-di-CQA, 0·7 g kg⁻¹; 3,5-di-CQA, 0·4 g kg⁻¹ and 4,5-di-CQA, 0·8 g kg⁻¹ dry matter. There were only small differences between the different brands. Two series of samples with different degrees of roast produced from the same green coffee have also been analysed. One series was steam treated before roasting (a process which is commercially used to improve digestibility). Only in the initial stages of roasting (light roast) could a difference in the contents of the acids between both series be observed. Keeping coffee brews at an elevated temperature (4 h at 80°C) reduced the amounts of CQL to 60% of the initial value. The contents of 3-CQA and 4-CQA increased, whilst that of 5-CQA decreased. The overall contents of CQA decreased.     

In vitro biohydrogenation and total tract digestibility of oleamide by sheep

Disappearance of cis-18:1(n-9) from ruminal in vitro cultures supplemented with either oleic acid or oleamide was measured over 48 h to determine if the amide resisted biohydrogenation. Oleamide added to the substrate maintained higher concentrations of cis-18: 1(n-9) in the microbial cultures at 24 and 48 h of incubation compared to substrates with added oleic acid. Disappearance rates of cis-18: 1(n-9) from the cultures, which were calculated as a measure of biohydrogenation, were 0·064 and 0·025 h⁻¹ for the oleic acid and oleamide supplements, respectively. Four sheep were fed four diets (control, 42 g kg⁻¹ oleic acid, 23 g kg⁻¹ oleamide, and 45 g kg⁻¹ oleamide) in a 4×4 Latin square to determine how the amide affected fatty acid digestibility. Total tract digestibilities of protein and fibre were not affected (P>0·05) by either oleic acid or oleamide compared to the control diet. Fatty acid and energy digestibilities were not changed (P>0·05) by oleic acid, but were increased (P<0·05) when oleamide was added to the sheep diets at 45 g kg⁻¹. These results show that oleamide resists ruminal biohydrogenation without impairing fatty acid digestibility. © 1998 SCI.     

Wet Milling Comparison of Quality Protein Maize and Normal Maize

Quality protein maize (QPM) experimental hybrids and normal maize possessing different physical and chemical properties were studied as the raw material for wet milling. Maize samples were steeped for 36 h in a 600-ml solution containing 15 g kg⁻¹ lactic acid and 0·5 g kg⁻¹ SO₂ followed by 12 h in a second 600-ml solution containing 5 g kg⁻¹ lactic acid and 1 g kg⁻¹ SO₂. The steeped grain was then wet milled and the yields and purity of fractions were analysed. Water-soluble solids, kernel size, quality protein, total dietary fibre and ash content were higher in QPM samples than in normal maize. Water-soluble solids were positively correlated to kernel size ( r =0·97, P< 0·05), test weight ( r =0·83, P< 0·05) and density ( r =0·57, P< 0·05). Total fraction recovery for the five hybrids tested ranged from 921 to 955 g kg⁻¹, with the highest values corresponding to QPM hybrids. QPM hybrids yielded slightly higher starch content than normal maize. Gluten yields of QPM-HO (high oil) presented the highest values. The lysine contents of kernel, gluten and milling solubles were highest for QPM hybrids. QPM contained more palmitic acid than the other hybrids. The H-137 normal maize and QPM yellow dent-HO contained more oleic and linolenic acids than the other samples, and the QPM white-C (corneous) contained more linoleic acid than QPM-HO and normal maize.     

The yield and carcass chemical composition of impala (Aepyceros melampus), a southern African antelope species

This investigation analyses the commercial carcass yields and chemical composition of impala (Aepyceros melampus). The potential of this species for the export market is also discussed. Impala rams (eight) and ewes (eight) cropped commercially in Zimbabwe were found to have a similar dressout proportion (580 g kg⁻¹), although the males had a heavier live weight (49.4 ± 4.606 kg) than the females (33.5 ± 3.417 kg). Sexual dimorphism was shown, with the males having significantly (p < 0.01) heavier necks (69 ± 5.47 g kg⁻¹) and forequarters (279 ± 3.79 g kg⁻¹) than the females (51 ± 1.70 and 259 ± 2.15 g kg⁻¹ respectively) when expressed as a proportion of cold carcass weight (27.6 ± 2.551 and 19.0 ± 1.960 kg for males and females respectively). No sexual effects (p > 0.2) were found in the mean chemical proximate composition of the 9‐10‐11 rib cut for the moisture (724.0 ± 14.00 g kg⁻¹ pooled sample), protein (238.3 ± 7.46 g kg⁻¹ pooled sample) and ash (21.2 ± 3.74 g kg⁻¹ pooled sample) contents. The females had a statistically higher (p = 0.0197) mean total lipid content (33.9 ± 1.705 g kg⁻¹) than the males (24.5 ± 3.171 g kg⁻¹). This investigation occurred at the end of the impala rut season, a period when the rams not only consume less feed but also expend more energy owing to strenuous activities in fighting for and maintaining a harem. © 2000 Society of Chemical Industry     

The Nutritive Value of Mango Seed Kernels for Starting Chicks

Raw mango ( Mangifera indica L) seed kernels were found to contain tannins (56·5 g kg⁻¹ DM), cyanogenic glucosides (64 mg kg⁻¹ DM), oxalates (42 mg kg⁻¹ DM) and trypsin inhibitory activity (20 TIU g⁻¹ DM). The contents of these anti-nutritive factors were lowered by both soaking and boiling treatments, but boiling was more effective. The in vitro protein digestibility (26·3%) and apparent metabolisable energy (7·88 MJ kg⁻¹ DM) values of raw kernels were low, and these parameters were improved by soaking and boiling. The observed improvements paralleled reductions in tannin contents, indicating that tannins are largely responsible for the poor nutritive value of raw kernels. In experiment 1, diets containing 0, 50, 100, 150 and 200 g kg⁻¹ raw mango seed kernels that replaced maize were fed to 7-day-old White Leghorn cockerels for 14 days. Inclusion of more than 50 g kg⁻¹ raw kernels lowered ( P< 0·05) the weight gains, feed intake and feed efficiency of chicks. High level inclusion of raw kernels had toxic effects, as evidenced by increased mortality. In experiment 2, soaking and boiling treatments improved ( P< 0·05) feed intake of chicks fed on diets containing 100 g kg⁻¹ kernels and reduced mortality. Feed/gain was unaffected by processing. Soaking had no effect, whereas boiling of kernels improved the weight gains. However, weight gains of chicks receiving diets containing 100 g kg⁻¹ boiled kernels were numerically, though non-significantly, lower than those of the maize-control group. It is concluded that raw mango seed kernels are unsuitable as a feed ingredient in chick diets and, that soaking and boiling do not completely overcome the anti-nutritive effects of raw kernels.     

Response of nutrient digestibilities to feeding diets with low and high levels of soybean trypsin inhibitors in growing pigs

Studies were carried out to determine the effect of dietary soybean trypsin inhibitor (SBTI) content on nutrient and energy digestibilities in growing pigs. Six barrows, average initial body weight (BW) 47·8±4·0 kg, were fitted with a simple T-cannula at the distal ileum and fed two diets according to a crossover design. Two maize starch-based diets were formulated to contain 200 g crude protein (CP) kg⁻¹ from either Nutrisoy (a food-grade defatted soy flour) or autoclaved Nutrisoy. The contents of SBTI in the Nutrisoy and autoclaved Nutrisoy diets were 13·4 and 3·0 g kg⁻¹, respectively. The experiment consisted of two periods of 12 days each. The average BW at the start of the first and second experimental periods were 53·3±3·7 and 61·0±5·1 kg, respectively. The average BW at the conclusion of the experiment was 71·8±7·6 kg. The ileal digestibilities of dry matter (DM), organic (OM), energy, CP and all amino acids measured were higher (P<0·01) in pigs fed the autoclaved Nutrisoy diet. The energy digestibility increased from 66·0 to 77·9%, and the CP digestibility increased from 37·4 to 77·1%. The increases in ileal digestibilities of the indispensable amino acids ranged from 27·0 (methionine) to 49·2 (leucine) percentage units. The increases in ileal digestibilities of the dispensable amino acids ranged from 30·2 (aspartic acid) to 50·8 (tyrosine) percentage units. The faecal digestibilities of all criteria measured were also higher (P<0·01) in pigs fed the autoclaved Nutrisoy diet. Furthermore, there was a greater (P<0·01) net disappearance (g kg⁻¹ DM intake) of DM, OM, CP, energy and all amino acids in the large intestine of pigs fed the Nutrisoy diet. In conclusion, feeding diets containing high levels of SBTI decreased both ileal and faecal digestibilities of all criteria measured. The formation of SBTI-enzyme complexes is likely to be responsible for the reduction in protein digestion and amino acid absorption. © 1998 SCI.     

Effects of intraruminal infusions of propionate and butyrate with two different protein supplements on milk production and blood metabolites in dairy cows receiving grass silage-based diet

Four cows were used in a balanced 4×4 Latin square with 2 week experimental periods to investigate the effects of intraruminal infusions of volatile fatty acids and protein source on milk production and blood metabolites. The four treatments in a 2×2 factorial arrangement were isoenergetic intraruminal infusions of propionate (500 g day⁻¹) or butyrate (417 g day⁻¹) each given with isonitrogenous protein supplementation of fish meal (FM) or barley protein (BP). The cows were fed restrictively with 9 kg dry matter day⁻¹ of formic acid treated grass silage and 8 kg day⁻¹ of concentrate. Propionate infusion increased milk yield (24·9 vs 23·4 kg day⁻¹; P<0·05), milk protein yield (832 vs 778 g day⁻¹; P=0·05) and milk lactose content (44·7 vs 43·5 g kg⁻¹; P<0·05) and yield (1113 vs 1023 g day⁻¹; P<0·01), whereas butyrate infusion was associated with a higher milk fat content (44·7 vs 39·4 g kg⁻¹; P<0·01) and yield (1033 vs 974 g day⁻¹; P<0·01). FM tended (P<0·10) to increase milk yield, but had no significant effects on milk composition or milk component yields compared with BP. Butyrate infusion increased blood ketones, plasma non-esterified fatty acids and glycine relative to propionate infusion. The concentrations of ammonia N in rumen fluid and urea in plasma and milk were similar for both protein supplements. The profile of amino acids in plasma was similar for both protein supplements except for the higher concentrations of phenylalanine, proline and tyrosine with BP. The results show that protein utilisation can be improved by increasing the supply of propionate from rumen fermentation in cows given a grass silage-based diet. © 1998 SCI.     

Proximate Composition and Seed Lipid Components of Sorghum Cultivars from Argentina

Seeds of 11 sorghum cultivars ( Sorghum bicolor ) from Argentina were analysed for proximate composition, fatty acids and sterols. Oil, protein, carbohydrate and ash contents varied between 41 and 66 g kg⁻¹, 111 and 156 g kg⁻¹, 670 and 730 g kg⁻¹ and 13·8 and 20·6 g kg⁻¹ of dry matter, respectively. Fatty acid profiles revealed that the major acids were palmitic (15·1–24·8%), oleic (29·9–41·8%) and linoleic (35·9–51·3%). Unsaponifiable matter was examined for sterols. Sitosterol was the prominent component in all cultivars (43·8–57·9%), followed by campesterol (18·7–29·1%) and stigmasterol (12·4–20·5%).     

Oven drying improves the nutritional value of Calliandra calothyrsus and Gliricidia sepium as supplements for sheep given low-quality straw

Leaves from the tree legumes Gliricidia (Gliricidia sepium) and Calliandra (Calliandra calothyrsus) were fed as supplements (200 g dry matter) to sheep (n=3) given a basal diet of barley straw ad libitum. Tree leaves were fed either freshly harvested (F=fresh) or after drying at 60°C in a forced draught oven (D=dried). Voluntary intakes, digestibility and aspects of nitrogen (N) and phenolic compound metabolism were measured in all sheep. Drying decreased the condensed tannin (CT) content of Calliandra (F 117, D 82 g CT kg⁻¹ DM). Total phenolics (TP) were significantly decreased when Gliricidia was dried (F 39, D 21 g TP kg⁻¹ DM), and CT content was reduced from 20 g CT kg⁻¹ DM to zero. Sheep given Gliricidia had higher rumen ammonia concentrations (73–85 mg N litre⁻¹) than did sheep given Calliandra (37–40 mg N litre⁻¹). For both species, drying significantly increased the voluntary consumption of straw, increased DM digestibility, decreased faecal N excretion and increased N balance. For calliandra, drying decreased the apparent degradability of N in the rumen (DNR) from 0·40 to 0·28 g N g⁻¹ N ingested, and increased the apparent digestibility of N (ADN) in the post-ruminal tract from 0·20 to 0·52 g N absorbed g⁻¹ N flowing into the small intestines. For Gliricidia, DNR decreased from 0·64 to 0·51 and ADN increased from 0·41 to 0·56. There were no significant effects of drying on rates of microbial N synthesis. The above changes were discussed in relation to changes in tannin content and it was concluded that drying facilitates the formation of protein–tannin complexes which protect proteins from degradation in the rumen. These proteins are subsequently released in the small intestines, thereby promoting an increased efficiency of dietary N utilisation. ©1997 SCI     

Optimization of cyclopropane fatty acids production in Yarrowia lipolytica

Cyclopropane fatty acids, which can be simply converted to methylated fatty acids, are good unusual fatty acid candidates for long-term resistance to oxidization and low-temperature fluidity useful for oleochemistry and biofuels. Cyclopropane fatty acids are present in low amounts in plants or bacteria. In order to develop a process for large-scale biolipid production, we expressed 10 cyclopropane fatty acid synthases from various organisms in the oleaginous yeast Yarrowia lipolytica, a model yeast for lipid metabolism and naturally capable of producing large amounts of lipids. The Escherichia coli cyclopropane fatty acid synthase expression in Y. lipolytica allows the production of two classes of cyclopropane fatty acids, a C17:0 cyclopropanated form and a C19:0 cyclopropanated form, whereas others produce only the C17:0 form. Expression optimization and fed-batch fermentation set-up enable us to reach a specific productivity of 0.032 g·L⁻¹·hr⁻¹ with a genetically modified strain containing cyclopropane fatty acid up to 45% of the total lipid content corresponding to a titre of 2.3 ± 0.2 g/L and a yield of 56.2 ± 4.4 mg/g.     

Aflatoxins and their Metabolites in the Tissues,Faeces and Urine from Lambs Feeding on an Aflatoxin-Contaminated Diet

Twenty-four lambs were intoxicated with 2·5 mg of aflatoxin (AF) kg^-1 in their feed for 21 days. Twelve lambs were slaughtered at day 21 and the remaining animals had an 8 day clearance period. Aflatoxins and their metabolites were detected in liver, kidneys, faeces and urine using TLC and fluorescence densitometry. During the intoxication period, the samples gave a wide range of concentrations, the lower extreme being in the liver and the kidney (0·03 μg kg^-1 of AFG₁) and the higher extreme in faeces (61·82 μg kg^-1 of AFM₁) and urine (27·84 μg litre^-1 of AFM₁). The average value of AFB₁ (1·94±0·9 μg kg^-1) was higher than AFM₁ (0·35±0·17 μg kg^-1) in the liver. In the kidney AFM₁ (5·45±4·01 μg kg^-1) was higher than AFB₁ (1·29±0·84 μg kg^-1). There were higher concentrations of AFM₁ (27·2±16·1 μg kg^-1, 7·37±6·53 μg litre^-1, respectively, of average level) in faeces and urine, than of AFB₁ (17·25±8·1 and 1·78±1·57 μg litre^-1, respectively). AFB_2a appeared in the kidney (0·05±0·03 μg kg^-1) and urine (0·35±0·25 μg litre^-1). The clearance time of AFB₁ from the faeces was less than or equal to 8 days and in all samples aflatoxin residues were still detected on the 8th day of the clearance period although in low quantities. These results suggest that aflatoxin transfer to and elimination by the liver and the renal tissue is small and that the danger to humans consuming lamb meat is also small. The examination of the faeces and urine could be useful as markers to detect lambs consuming a contaminated diet. © 1997 SCI.     

Faecal Composition and Nitrogen Excretion of Rats Fed on Diets Containing Sweet Lupin (Lupinus angustifoliusL) or its Fractions

Five N balance studies were conducted to determine the faecal composition and N excretion of feeding raw Lupinus angustifolius seed meal and its fractions for growing rats using a semi-synthetic lactalbumin-based diet as control. Diets were formulated to have equal amounts of energy. The protein was incorporated at the level of 10% bulk and contained unsupplemented lupin seed meal (LMU) and fully supplemented lupin seed meal (LMFS) at 360 g kg⁻¹ diet, aqueous extract non-dialysed (LPAND) at 196 g kg⁻¹ aqueous extract dialysed soluble at pH 7·0 (LPAD) at 148 g kg⁻¹ aqueous extract dialysed insoluble at pH 7·0 (LPADI) at 124 g kg⁻¹, buffer dialysed soluble at pH 7·0 (BUSOL) at 136 g kg⁻¹, buffer dialysed insoluble at pH 7·0 (BUDI) at 119 g kg⁻¹ and lupin meal residue after aqueous and buffer extraction (LMR) at 170 g kg⁻¹ diet. Rats were pair-fed for 10 days with all the above diets which had been supplemented with essential amino acids up to the target requirements for rats. Faecal wet and dry weight were increased in rats fed on LMU, LMPS and LMR diets compared to those obtained from the control diet based on lactalbumin (milk protein) LACT. The higher faecal weight was largely due to water content. The higher faecal N excretion observed in LMU, LMFS, LPAND, LPAD, BUSOL, BUDI and LMR compared to that of LACT diet was significantly lower and thus which was assumed not to be due to a decrease in the digestibility of the dietary protein, which was over 90% as compared to that in the control group. Analysis suggested that an increase in endogenous N excretion is involved in the rise of its excretion in the faeces, and indicates a long-term effect of this seed as a protein and or fibre source in monogastrics.     

Sugar Beet Grown Using Nutrient Film Technique: Yield and Nutritional Quality

Sugar beet (Beta vulgaris L cv Great Western Sugar) was grown using the nutrient film technique with a half-strength modified Hoagland nutrient solution to determine its biomass yield and nutritional quality. After 6 months, storage root and foliage weights per plant were 493·1 g and 551·0 g, respectively. Sucrose content in the fresh storage root was 118·4 g kg⁻¹ but was less than 10 g kg⁻¹ in the fresh leaves and petioles. Some nutrients in the leaves and petioles were analysed to evaluate their potential as a leafy vegetable. Fresh leaf protein, total dietary fibre, mineral (Ca, Mg, Zn, Fe and K), vitamin (carotene, ascorbic acid and thiamine) and oxalic acid concentrations were similar to those of consumer-accepted green vegetables.