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.     

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.     

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     

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.     

The Nutritional Value of High-Lysine Barley Determined in Rats,Young Pigs and Growing Pigs

Three experiments, the first with rats, the second with young pigs and the third with growing pigs, were carried out to compare the nutritional value of cv Lysimax, a newly developed high-lysine barley, to cv Lami, a conventional barley grown in Denmark. In the diets for rats and growing pigs the barleys were the sole protein source while in the experiment with young pigs the barleys made up to 649 g kg^-1 of the respective diets. The lysine content of cv Lysimax was 52·6% higher than that of cv Lami; 4·99 g 16 g N^-1 compared to 3·27 g 16 g N^-1. The contents of threonine, tryptophane, methionine and cystine of cv Lysimax were 3·80, 1·41, 1·80 and 2·27 g 16 g N^-1, respectively; being 18·4, 8·5, 9·8 and 5·1% higher than in cv Lami. Conversely, the contents of glutamic acid and proline in cv Lysimax were 15·79 and 7·40 g 16 g N^-1, respectively, being 36·1 and 40·0% lower than in cv Lami. In the experiment with rats, the higher lysine content and the lower content of glutamic acid and proline in cv Lysimax resulted in a 34·8% increase (P<0·05) in biological value (BV); 0·867 for cv Lysimax compared to 0·643 for cv Lami. True protein digestibilities and energy digestibilities in rats fed cv Lysimax were 0·019 and 0·010 units lower (P<0·05) than for cv Lami. For young pigs the increased lysine content and the lower content of glutamic acid and proline of cv Lysimax increased (P<0·05) nitrogen (N) retention from 10·9 to 12·4 g day^-1, respectively, and increased (P<0·05) apparent BV from 0·690 to 0·734, respectively. The digestibility of energy was 0·030 units lower (P<0·05) for the diets with cv Lysimax than for the diets with cv Lami. Likewise, with growing pigs the increased lysine content and the lower content of glutamic acid and proline increased (P<0·05) N retention from 6·4 to 10·8 g day^-1 and apparent BV from 0·271 to 0·495, respectively. The apparent ileal digestibilities of lysine, threonine, tryptophane, methionine and cystine were similar (P>0·05) between the barleys. It is concluded that the development of high-lysine barley varieties could be beneficial for meeting the requirements of essential amino acids for monogastrics. Moreover, N excretion into the environment was substantially reduced due a reduction in the prolamine fraction which is rich in glutamic acid and proline. © 1997 SCI.     

Nitrogen in browse species: ruminal degradability and post-ruminal digestibility measured by mobile nylon bag and in vitro techniques

This study determined nitrogen degradability and digestibility of rumen undegradable nitrogen using mobile nylon bag (MNB) and pepsin/pancreatin in vitro technique (IV) of 40 browse species. Thirty Ethiopian highland sheep fitted with rumen cannulae were used in nitrogen (N) degradability studies. Six steers fitted with rumen cannulae were used in preparation of 16-h and 24-h ruminal undegraded residues and four steers fitted with distal abomasal cannulae were used in MNB technique. The browses varied widely in nitrogen solubility (15–468 g kg⁻¹), potential degradability (223–976 g kg⁻¹), rate of degradation (0·13–24% h⁻¹) and effective degradability (135–821 g kg⁻¹). The apparent N digestibility (ND) of the rumen undegraded residues differed significantly (P<0·05) among browse species. No significant difference (P>0·05) was observed in ND of 16-h and 24-h residues. The ND of the 16-h residue varied from -218 to 759 g kg⁻¹ and 169 to 851 g kg⁻¹ for MNB and IV methods, respectively. Browse species with high tannin contents such as Acacia hockii, A horrida, A melanoxylon, A persiciflora, A salicina, A saligna and Flemingia macrophylla had high rumen by-pass and a low ND, while Sesbania spp and A nilotica with low tannin contents underwent rapid and extensive dry matter and nitrogen degradation in the rumen. Acacia sieberiana, Chamaecytisus palmensis, Erythrina spp, Gliricidia sepium, Samanea saman and Enterolobium cyclocarpum had high proportions of protein escaping rumen degradation (BP ) and with a high proportion of the by-pass protein digested in the intestine, therefore these browses had a high potential as protein supplements. The ND measured with the MNB were significantly lower (P<0·001) than by the IV method. The correlation between MNB and IV was high and significant (R²=0·89, P<0·0001) as also indicated by the regression equation (SE in parentheses): MNB=-22·8 (4·55)+1·0 (0·08)IV (RSD=10·56, R²=0·79, n=40, P<0·001). The intercept of the linear relationship obtained was different from zero while the slope was not different from unity. Multiple regression analysis suggested that some of the unexplained variation could be accounted for by either nitrogen, acid detergent fibre, total phenolics or neutral detergent fibre bound tannin levels in browses. The IV method is accurate for estimating digestibility of ruminally undegradable N, and hence its use would considerably reduce the need for delicate surgery and the elaborate procedures involving the MNB technique. © 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%).     

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.     

Effects of Silage Fermentation and Post-ruminal Casein Supplementation in Lactating Dairy Cows: 1—Diet Digestion and Milk Production

Two silages were prepared from the first-cut sward of timothy-meadow fescue and wilted to a dry matter (DM) content of 300 g kg^-1. One was ensiled with the addition of a formic-acid-based additive (4 litres formic acid (FA) per tonne) and the other with the addition of a bacterial inoculant (LAB) at a rate of 5×10⁶ colony forming units g^-1. Both silages were well preserved, but the extent of fermentation was greater in LAB-silage than in FA-silage as indicated by a lower concentration of water soluble carbohydrates (68 vs 177 g kg^-1 DM) and a higher concentration of lactic acid (147 vs 32 g kg^-1 DM). Four Ayrshire cows were used in a 4×4 Latin square experiment with 21-day periods to study the effects of silage fermentation and postruminal casein supplementation on silage intake, nutrient supply and milk production. The four treatments were FA-silage without casein (FA-0), LAB-silage without casein (LAB-0), FA-silage with casein (FA-C) and LAB-silage with casein (LAB-C). Both silages were given ad libitum with 8 kg day^-1 of barley without or with 400 g day^-1 of casein infused into the duodenum. Organic matter digestibility was lower (0·723 vs 0·753; P<0·01) for FA-silage than for LAB-silage. Cows offered FA-silage had a higher molar proportion of acetate and a lower proportion of propionate in ruminal fluid than cows offered LAB-silage. Microbial protein synthesis estimated from the output of purine derivatives in urine was greater (288 vs 260 g N day^-1; P<0·05) for cows given FA-silage compared with LAB-silage. Feeding LAB-treated silage tended (P<0·10) to decrease silage DM intake compared with FA-treated silage (10·61 vs 11·77 kg DM day^-1). Silage composition did not affect significantly milk yield or milk composition. Casein infusion increased milk yield (25·1 vs 27·1 kg day^-1; P<0·05), milk protein content (32·4 vs 33·8 g kg^-1; P<0·05) and protein yield (808 vs 905 g day^-1; P<0·01). The responses were similar for both silages. © 1997 SCI.     

Proximate,Fatty Acid and Sterol Compositions of Aboriginal Peanut (Arachis hypogaea L) Seeds from Bolivia

Oil, protein, ash, carbohydrate, iodine value, fatty acid and sterol compositions were studied in 46 aboriginal Arachis hypogaea cultivars originating from Bolivia. The oil and protein contents varied between 440 and 547 g kg^-1 and 242 and 547 g kg^-1, respectively. Results showed a lower protein content in the variety hypogaea (264·4 g kg^-1) than in the varieties fastigiata (299·7 g kg^-1) and peruviana (294 g kg^-1). The carbohydrate content ranged between 86 and 216 g kg^-1. The principal fatty acids were oleic (358–536 g kg^-1) and linoleic (250–462 g kg^-1). The variety hypogaea exhibited higher concentrations of oleic acid (449·0 g kg^-1). The sterol composition showed higher concentration of β-sitosterol (554–632 g kg^-1) following by campesterol (139–180 g kg^-1), stigmasterol (82–130 g kg^-1) and Δ⁵-avenasterol (86–138 g kg^-1). © 1997 SCI.     

Caecal metabolites and microbial populations in chickens consuming diets containing a mined humate compound

The objectives of this study were to compare the short-chain fatty acid (SCFA) concentrations, amino acid concentrations and key carbohydrate-fermenting anaerobic bacterial populations in the caeca of chickens consuming either control diets or a mined humate compound (MH; Menefee Humate^TM). Dietary MH at concentrations of 0, 5 or 10 g kg⁻¹ did not affect (P ⩾ 0·05) the caecal concentrations of SCFA and amino acids. Regardless of treatment, acetate was found to be the predominant SCFA in the caecum followed by propionate (P < 0·05). MH had no effect on the caecal concentrations of 17 amino acids compared with control birds but, when analysed across treatments, glutamate was found to be the predominant free amino acid in the caecum, followed by alanine (P < 0·05). MH did not significantly influence any of the anaerobic microbial populations but Escherichia coli populations from birds receiving either 10 or 50 g kg⁻¹ MH were between 10 and 100 times greater than control birds (P < 0·05). It appears that MH does not influence concentrations of fermentation acids or amino acids in the caecum but may influence levels of individual microbial populations. © 1998 SCI.     

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.     

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     

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.     

Genetic and environmental variability in starch,fatty acids and mineral nutrients composition in cowpea (Vigna unguiculata (L) Walp)

Fifteen cowpea cultivars grown in three locations (Kano (12°00′N 8°31′E), Mokwa (9°17′N 5°04′E) and Ago-Iwoye (6°58′N 4°00′)) between 1993 and 1994 were analysed for genotype, environmental and genotype×environment variability for starch (g kg⁻¹), fatty acids (% of total oil) and mineral nutrients (g kg⁻¹) composition. There were significant environmental as well as genetic effects on these nutritional qualities. The environmental effect accounted largely for the variability observed in starch (60%), palmitic acid (80%), arachidic acid (100%), potassium (100%), phosphorus (81%) and manganese (86%), while the genotypic effect accounted largely for the variability observed in linoleic acid (50%), linolenic acid (50%) and copper (68%) contents. Correlation coefficient (pooled data) from the three locations indicated that starch was positively correlated to palmitic acid (r = 0·21, 0·01< P < 0·05), potassium (r = 0·80, P < 0·001) and phosphorus (r = 0·65, P < 0·001), but negatively correlated to oleic (r = −0·23, 0·01< P < 0·05), linoleic (r = −0·67, P < 0·001) and linolenic acid (r = −0·74, P < 0·001) contents. Starch showed a strong positive correlation with magnesium content (r = 0·75) and a strong negative correlation with copper (r = −0·73) and iron (r = −0·62) at the genetic level. This research established the degree of variability for these characters in cowpea. © 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 composition,digestibility and protein quality of 12 sunflower (Helianthus annuus L) cultivars

Twelve sunflower (Helianthus annuus L) cultivars grown in Spain were analysed and tested in experiments with rats. The dehulled seeds contained an average of 32.2 MJ kg⁻¹ dry matter (DM) gross energy, 653 g kg⁻¹ DM fat, 60 g kg⁻¹ DM total non-starch polysaccharides (NSP) and 6 g kg⁻¹ DM Klason lignin. The sunflower seed hulls contained 20.2 MJ kg⁻¹ DM gross energy, 53 g kg⁻¹ DM fat, 562 g kg⁻¹ DM total NSPs and 239 g kg⁻¹ DM Klason lignin. The sunflower samples were dehulled and partially defatted (to ∼17% fat) and included in diets for rats. The dehulled, partially defatted samples contained on average 74.6 g nitrogen kg⁻¹ DM and 1.409 mg g⁻¹ phenolic compounds (chlorogenic acid + caffeic acid + derivative 1 + derivative 2) varying from 0.677 to 2.847 mg g⁻¹. Groups of five growing rats were fed diets (9.38% crude protein) containing one of the sunflower cultivars as the only source of protein. Apparent ileal and faecal digestibilities were determined by using an indigestible marker (Cr₂O₃) and faecal digestibility based on total faecal collections. Apparent ileal, caecal and faecal digestibilities of organic matter were 81.2–91.5% (P = 0.05), 95.8–97.1% (P = 0.005) and 94.7–95.3% (P = 0.94) respectively. The apparent faecal digestibilities of DM, energy and protein (N × 6.25) were 93.2–93.8%, 93.5–94.3% and 81.6–84.3% respectively with no differences among cultivars. Biological value (BV) ranged between 63.8 and 73.2% (P = 0.0001) and net protein utilisation (NPU) between 59.9 and 69.5% (P = 0.0001). BV and NPU were positively correlated with lysine and threonine contents, but no correlation with the analysed phenolic compounds was detected. © 1999 Society of Chemical Industry     

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     

Influence of Fermentation Time and an ‘Indigenous Tenderiser’ (Kanwa) on the Microbial Profile,Chemical Attributes and Shelf-Life of Rice Masa (a Nigerian Fermented Product)

Investigations on the influence of fermentation time, ‘Kanwa’ (an indigenous tenderiser and a flavouring agent) and potassium sorbate (0·5, 1·0 or 1·5 g kg⁻¹) were conducted by examining the microbial profile, chemical attributes and shelf-life of rice ‘Masa’ (a Nigerian fermented product). Various types of microorganisms occurred at the initial stages of rice slurry fermentation and these included fungi (Aspergillus spp, Penicillium spp, Saccharomyces spp, Rhizopus spp) and bacteria (Lactic acid bacteria, Bacillus spp, Enterobacter spp and Acetobacter spp). But beyond 8 h fermentation time, fewer types of micro-organisms (Lactobacillus spp, Saccharomyces spp and Rhizopus spp) were isolated.Total aerobic counts increased significantly (P=0·05) as fermentation progressed (0, 6 or 12 h), with lactic acid bacteria (LAB) and yeasts dominating and probably contributed to the sour–sweet spongy characteristic of the rice Masa. But after fermentation and baking process, the rice Masa became dominatedand spoilt by Bacillus spp, Lactobacillus spp and Saccharomyces spp withstorage time. Longer fermentation time resulted in a less acceptable product,being more acidic. Rice Masa produced from a 6 h fermentation showedbetter sensory qualities (aroma and visual appearance). Use of Kanwa(Na₂CO₃.NaHCO₃.2H₂O) improved aroma but was detrimental to visualappearance and spoilage was accelerated, probably due to higher pH. Potassium sorbate at higher concentrations (1·0 and 1·5 g kg⁻¹) induced beneficial antimicrobial effects and reduced the microbial load thereby prolonging the shelf life of the rice Masa (treated with 1·5 g kg⁻¹) by about 3 days.     

High-pressure-induced changes in the characteristics of low-fat and high-fat sausages

The purpose of this study was to analyse the consequences of applying high pressures (100 and 300 MPa for 5 and 20 min) on characteristics such as water and fat binding properties, texture, colour, microstructure and microbiology of low-fat (90 g kg⁻¹, LF) and high-fat (247 g kg⁻¹, HF) meat emulsions. Pressurising of LF and HF samples at 300 MPa caused a decline (P<0·05) in emulsion stability, which was more pronounced at the higher pressure. The influence of high pressures on emulsion texture varies according to fat content. In HF samples, high pressure caused a decrease (P<0·05) in Kramer shear force and Kramer energy, regardless of pressure intensity or time. Pressurisation generally caused increase (P<0·05) in the colour lightness parameter in sausages; the effect on redness and yellowness, however, was dependent on fat content, pressure intensity and pressure time. © 1997 SCI.