Some effects of fibre and starch on the determination of protein quality

An assessment was carried out of the effects of an increase in the amount of fibre, as cellulose, and of a replacement of maize starch by potato starch in diets containing egg albumen as the sole protein, on the determination of true digestibility (TD) and biological value (BV). An increase in the fibre content of the diet at the expense of maize starch led to a rise in both fascal and urinary N excretion, with diets containing either 20 or 80 g egg albumen kg^?1. However, the response of the rats to increasing fibre concentration in the diet was different for the two levels of protein probably due to differences in dry matter intake (DMI). It was found that the conventional method of estimating metabolic faecal nitrogen (MFN) was not adequate for diets of decreasing digestibility; TD decreased by 0.35% for a rise of 1% cellulose in the diet. A more accurate method of estimating MFN was derived from a relationship between the N in the faeces and the digestibility of the diet. The increase in urinary N excretion led to a decrease of 0.41% in BV for a 1% rise in the cellulose concentration of the diet. It appears, therefore, that the ratio of digestible to indigestible matter in the diet affects the determination of protein quality. The replacement of maize starch by potato starch in the diet caused an increase in faecal N excretion and a decrease in urinary N excretion until a level of 200 g potato starch kg^-1 was reached. This affected the determination of TD and BV accordingly. An increase in the size of the caecum of the rats fed potato starch indicated that increased fermentation may have resulted in production of additional bacterial cells to be excreted in the faeces. Thus, both the amount of fibre and the type of starch in the diet affect the determination of protein quality.     

The determination of endogenous urinary nitrogen in protein quality studies with rats

The determination of the endogenous urinary nitrogen (EUN) excretion in protein quality studies using the Thomas-Mitchell method with rats has usually been estimated using either a protein-free or low concentration egg protein diet. Generally no effort has been made to equate EUN excretion with the urinary nitrogen excretion in the urine whilst the rat is in a state of maintenance. An attempt was made to find the diet which would maintain the weight of the rats used to determine the EUN at the time of the balance period of the protein quality test animals. It was found that a diet containing 20 g egg albumen kg^?1 came the nearest to fulfilling this criterion and was the diet most suitable for the determination of the EUN.     

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.     

Dietary non-extractable condensed tannins as indigestible compounds: Effects on faecal weight,and protein and fat excretion

The possible degradation of non-extractable condensed tannins (NECT) within the intestinal tract and their effect on faecal weight and composition was studied. Two groups of male Wistar rats were fed either a NECT-free control diet, or a diet containing 100 g carob pod concentrate kg^?1 (53 g NECT kg^?1 dry matter) for 5 weeks. A slight effect of NECT on growth rate was observed in the fifth week. The NECT diet did not affect food intake. Significant increases of total faecal output as well as water, nitrogen and fat excretion were observed. NECT were not degraded in the intestinal tract, since they were quantitatively recovered in faeces (98 ± 1%). Since the usual spectrophotometric methods gave contradictory results on NECT levels in the diet and faeces, an alternative method based on Klason lignin residues was used.     

Effect of phytase inclusion and calcium/phosphorus ratio on the performance and nutrient retention of grower–finisher pigs fed barley/wheat/soya bean meal‐based diets

Two experiments were conducted to evaluate the effects of phosphorus (P) level and calcium (Ca)/total P (tP) ratio on the efficacy of microbial phytase. Experiment 1 examined the effects of P concentration and microbial phytase inclusion on mineral excretion and pig performance, while experiment 2 examined the effects of Ca/tP ratio and microbial phytase inclusion on mineral excretion and pig performance. In experiment 1, nutrient and mineral digestibility (n = 4) and growth performance (n = 12) were determined in pigs individually fed diets containing (T1) 5.5 g kg^?1 tP, 2.3 g kg^?1 available P (aP) and 8.0 g kg^?1 Ca, (T2) 5.5 g kg^?1 tP, 2.3 g kg^?1 aP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 Peniophora lycii phytase, (T3) 4.3 g kg^?1 tP, 1.4 g kg^?1 aP and 8.0 g kg^?1 Ca and (T4) 4.3 g kg^?1 tP, 1.4 g kg^?1 aP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase. In experiment 2, nutrient and mineral digestibility (n = 4) and growth performance (n = 12) were determined in pigs individually fed diets containing (TT1) 4.3 g kg^?1 tP and 8.0 g kg^?1 Ca, (TT2) 4.3 g kg^?1 tP, 8.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase, (TT3) 4.3 g kg^?1 tP and 5.0 g kg^?1 Ca and (TT4) 4.3 g kg^?1 tP, 5.0 g kg^?1 Ca and 750 FYT kg^?1 P lycii phytase. All diets were formulated, using standard feeding values for the ingredients, to have similar concentrations of digestible energy (DE) and lysine. In experiment 1, pigs offered the low‐P diets had significantly lower P intake (P < 0.001), faecal P excretion (P < 0.05), Ca intake (P < 0.05) and faecal Ca excretion (P < 0.05) compared with pigs given the adequate‐P diets. These pigs also had significantly lower daily gain (P < 0.01), feed intake (P < 0.05) and feed conversion ratio (FCR) (P < 0.05). The inclusion of phytase in both the adequate‐ and low‐P diets increased the digestibility of energy (P < 0.05) and Ca (P < 0.01) but had no effect on pig performance. In experiment 2, lowering the Ca/tP ratio from 1.85:1 to 1.15:1 increased the DE content of the diet (P < 0.05). The inclusion of phytase increased (P < 0.05) the digestibility of protein (0.874 versus 0.840, SEM 0.009) and Ca (0.427 versus 0.380, SEM 0.019) as well as the DE content of the diet (14.47 versus 14.26 MJ kg^?1, SEM 0.073). There was a significant ratio × phytase interaction (P < 0.5) for P digestibility. Microbial phytase significantly increased P digestibility when added to the 1.15:1 ratio diet but had no effect when added to the 1.85:1 ratio diet. The inclusion of microbial phytase increased feed intake (2.16 versus 2.00 kg day^?1, SEM 0.05; P < 0.05) and weight gain (0.893 versus 0.818 kg day^?1, SEM 0.022; P < 0.05). Lowering the Ca/tP ratio resulted in a significant improvement in FCR (2.32 versus 2.40 kg kg^?1, SEM 0.03; P < 0.05). In conclusion, the beneficial effects of microbial phytase supplementation of pig diets are adversely affected by a wide Ca/tP ratio. © 2002 Society of Chemical Industry     

Nutritional value of animal feed grade wheat as replacement for maize in lamb feeding for mutton production

The utilization of abundantly available animal feed grade wheat (AFW) as a replacement for conventional and costly cereal supplement in lamb feeding to lower the cost of mutton production was explored. Thirty‐five growing lambs divided into five equal groups and were fed diets containing 0, 118, 235, 353 or 470 g kg^?1 AFW replacing equal quantity of maize. The diets were fed in the form of composite feed mixture, which had a roughage (Prosopis cineraria leaves) to concentrate ratio of 25:75. Dry matter intake (DMI) was not different in these groups, ranging from 35 to 42 g kg^?1 body weight, while AFW inclusion linearly (P < 0.05) reduced DMI. The digestibility coefficients of dry matter (DM), organic matter (OM), crude protein (CP) and cellulose were not affected by AFW addition, whereas neutral detergent fibre and acid detergent fibre digestibility coefficients were reduced (P < 0.05). The digestible CP content (142.7–162.7 g kg^?1 diet) increased (P < 0.01) linearly with increased AFW inclusion levels. However, AFW additions did not affect metabolizable energy (ME) value of diet (10.2–10.5 MJ kg^?1 diet DM). Digestible CP intake was similar but digestible DM and OM intake tended to decrease (P < 0.05) linearly when expressed in terms of g kg^?1 W^0.75. ME intake (MJ d^?1) was not different among the diets but showed linear (P = 0.041) reducing trends with increasing AFW levels in diet. The efficiency of ME and N utilization for unit gain was also not affected by AFW incorporation. N retained as g d^?1, percentage of intake and percentage of absorbed ranged from 15.4 to 19.5 g, 49.7% to 60.3% and 62.6% to 74.6%, respectively. Intake and utilization of dietary N was not affected but urinary N excretion reduced (P < 0.05) linearly by AFW. Daily microbial N (MN) flow estimated by urinary purine derivative excretion was significantly (P < 0.01) higher for lambs fed a diet with AFW 235 g kg^?1 (3.05 g MN) and 353 g kg^?1 (2.51 g MN) compared to without AFW diet (1.31 g MN). MN when expressed as g kg^?1digestible organic matter intake (DOMI) and microbial protein g kg^?1 digestible organic matter apparently fermented in rumen (DOMR) followed a similar trend. During the growth trial, lambs fed diets containing AFW (353 g kg^?1), which replaced 75% maize had higher total gain (14 kg, P < 0.05) and average daily gain (ADG 154 g, P < 0.05). However, feed efficiency (feed consumed kg^?1 live weight gain) was not different. Rumen pH and microbial enzyme activities studied 4 h post feeding revealed that AFW did not affect rumen pH, which ranged from 5.95 to 6.30. Similarly, carboxymethyl cellulase and β‐xylosidase enzyme activities were not different among treatments, but AFW inclusion linearly (P = 003) increased carboxymethyl cellulase enzyme activities. The α‐amylase enzyme activity differed significantly (P < 0.05) and was highest (22.6 IU) in groups where AFW replaced maize completely. It was concluded that, in lambs reared under intensive system for mutton production on high concentrate diets, conventional and costly energy supplements like maize can be replaced up to 75% with a low‐cost animal feed grade wheat to economize on cost of production. However, more studies are required to confirm these inclusion levels for greater economic returns. Copyright © 2007 Society of Chemical Industry     

Chemical composition,nutritive value and voluntary intake of tropical tree foliage and cocoyam in pigs

The composition of the leaves of cocoyam (Xanthosoma sagittifolium) and of two trees (Trichanthera gigantea and mulberry, Morus alba), their nutritive value in pigs and voluntary intake by pigs were determined. The average protein content ranged from 170 to 240 g kg^?1 dry matter (DM) and that of neutral detergent fibres from 218 to 398 g kg^?1 DM. The leaves are interesting sources of calcium (up to 69 g kg^?1 DM), potassium, iron and manganese. The proteins are well balanced in essential amino acids, with lysine ranging from 43 to 57 g kg^?1 proteins. The apparent faecal digestibility was determined by difference in 35 kg pigs fed a diet containing 35% leaf meal. The digestibility coefficients of DM, N and energy were, respectively, 47–57, 33–36 and 51–53%. The digestible energy value ranged from 1.674 to 2.037 kcal kg^?1 DM. The voluntary intake of Trichanthera and Xanthosoma was measured in sows weighing 100 kg on average. The intake reached 3.4 kg fresh leaves day^?1 (0.51 kg DM) and 1.0–1.1 kg dry leaf meal/day. It is concluded that low energy density is the main limiting factor of tree foliage for pig nutrition but that they are good sources of minerals and well‐balanced proteins. Copyright © 2005 Society of Chemical Industry     

Nutrient digestibility,performance and carcass traits of growing–finishing pigs fed diets containing graded levels of dehydrated lucerne meal

BACKGROUND: Plant breeders have attempted to improve the nutritonal value of lucerne (alfalfa) by selecting for higher protein and lower fibre concentrations. Although targeted at ruminants, such changes could also improve the nutritional value of lucerne for monogastrics. The objective of this study was to determine the effects of graded levels of dehydrated lucerne meal on nutrient digestibility, performance and carcass traits of swine. RESULTS: The digestibility of dry matter, protein and energy declined linearly (P < 0.05) as the level of lucerne meal in the diet increased. Including lucerne meal at levels greater than 75 g kg^?1 was detrimental to the growth rate of pigs during the growing period. During the finishing period, inclusion of lucerne meal at 75 and 150 g kg^?1 resulted in improvements in weight gain and feed intake. Carcass traits were generally unaffected by lucerne inclusion. CONCLUSION: Lucerne meal may have greater potential for inclusion in diets fed to growing–finishing pigs than previously realized. To maximize pig performance, lucerne meal should be limited to less than 75 g kg^?1 diet during the growing period, while it is possible to go as high as 150 g kg^?1 diet during the finishing period without detrimental effects on performance. Copyright © 2008 Society of Chemical Industry     

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     

Rice Protein Isolates Produced by the Two Different Methods Lower Serum Cholesterol Concentration in Rats Compared with Casein

Highly purified rice protein isolates (RPI) were prepared by an alkaline extraction–acid precipitation method (E-RPI) and by an α-amylase treatment to remove starch (T-RPI). Biological values of these RPI were significantly lower than that of casein. Serum cholesterol concentrations were compared among groups of rats fed (per kg diet) 200, 300 or 400 g E-RPI, 400 g T-RPI, 250 or 400 g casein kg⁻¹ or 400 g soya bean protein isolate (SPI). With all the diets containing 400 g protein kg⁻¹ diet, growth rates of rats were the same. At this level, E-RPI, T-RPI and SPI diets produced significantly lower serum cholesterol concentrations than the casein diet. Faecal bile acid plus neutral steroid excre-tion was significantly higher in rats fed the 400 g kg⁻¹ T-RPI or 400 g kg⁻¹ SPIdiets compared with rats fed the 400 g kg⁻¹ casein diet. On the other hand, the 400 g kg⁻¹ E-RPI diet did not increase steroid excretion. Plasma cholesterol concentrations in rats fed diets with amino acid mixtures simulating SPI and E-RPI were also significantly lower than that of rats fed the diet with an amino acid mixture simulating casein even though the faecal excretions of total bile acids were the same amongst groups. These results support the view that RPI are hypocholesterolaemic relative to casein and at least the hypocholesterolaemic effects of E-RPI would be independent of interruption of the enterohepatic circulation of endogenous steroids.     

Response of growing Japanese quails to dietary concentration of L‐threonine

The influence of dietary levels of L ‐threonine (Thr) on growth and immune response was investigated in growing (0–5 weeks of age) Japanese quails (n = 288). Three dietary treatments were formulated using three levels of Thr [9.6, 10.2 and 11.2 kg^?1 diet dry matter (DM)] at a fixed protein level of 233 g kg^?1 and an energy level of 12.15 MJ (2900 kcal) metabolizable energy (ME) kg^?1 feed dry matter. A metabolism trial with a 3‐day collection period was conducted at the third week of age employing all the birds. The cell‐mediated (using PHA‐P) and humoral (SRBC response) immune responses were measured at the fourth week of age. Carcass traits were assessed at the end of fifth week of age. Body weight gain was lower (P < 0.01) in birds received 9.6 g Thr kg^?1 DM than in groups fed 10.2 g or 11.2 g kg^?1 DM in the diet, but there was no significant difference in gain between the groups fed 10.2 or 11.2 g Thr kg^?1 DM in the diet. Feed intake differed significantly owing to Thr levels being lowest (P < 0.05) at 9.6 g Thr kg^?1 DM in the diet. Feed conversion ratio (FCR), protein efficiency and energy efficiency improved at the 11.2 g kg^?1 level from 0 to 3 weeks of age; however, from 3 to 5 weeks of age, better FCR emanated from a diet with 9.6 g Thr kg^?1 DM. The nitrogen balance did not differ (P > 0.05) with Thr level. Carcass traits, relative weight of immune organs and cell‐mediated (PHA‐P) and humoral (SRBC response) immune responses did not differ significantly (P > 0.05) as a result of the dietary treatments. Copyright © 2006 Society of Chemical Industry     

Effects of methionine addition in soya bean or casein diets supplemented with carrageenan on weight gain and blood lipids in rats

Seven groups of 12 Wistar rats were fed during two experimental periods. During the first period of 4 weeks, rats were fed diets containing 100 g kg^?1 of casein or soya-protein. In the case of casein, diets contained casein, casein + 3.5 g kg^?1 of sodium carrageenan and casein + 3.5 g kg^?1 of sodium carrageenan + 1 g kg^?1 of DL-methionine. In the case of soya protein, diets contained soya protein, soya protein + 6.2 g kg^?1 of sodium carrageenan, soya protein + 6.2 g kg^?1 of sodium carrageenan + 1 g kg^?1 of DL-methionine and soya protein + 1 g kg^?1 of DL-methionine. During the second period of 8 weeks, all rats were fed laboratory pellets containing 170 g kg^?1 of standard protein mixture. Methionine supplementation of heated soya bean meal containing carrageenan prevented the decrease of growth observed with unsupplemented diet. Methionine supplementation of casein improved protein efficiency ratio and had no effect on long-term growth of rats because carrageenan did not cause growth retardation. At the end of second period, carrageenan ingested during the first period had no effect on plasma cholesterol. When carrageenans added to casein were ingested during the first period, plasma triglycerides were significantly lower after the second period. It would seem that carrageenans induce protein malnutrition by a lack of methionine when they are present in low protein diets with low methionine content, and that a sufficient content of methionine in diets prevents the carrageenan effect.     

Acacia saligna as a fodder tree for desert livestock and the interaction of its tannins with fibre fractions

Acacia saligna was examined as potential fodder for sheep (27.4 kg) and goats (14.8 kg) raised in arid and semi-arid areas. This leguminous tree remains green all year and can be grown in deserts using only runoff water. Phyllodes collected in March had a crude protein content of 12.5% dry matter (DM) and high tannin content (tannins as tannic acid equivalent to 11.3% and condensed tannins as leucocyanidin equivalent to 8.3% DM). DM intake was low, amounting to 0.80% and 1.05% body mass daily for sheep and goats, respectively. Sheep lost 227 g day^?1 and goats 196 g day^?1 while on this diet. Dry matter, organic matter and energy digestibilities were low in both species but were higher for goats than for sheep, and negative digestibilities were measured for acid detergent fibre (ADF) and acid detergent lignin (ADL). Metabolisable energy intake for goats was 121.9 kJ kg^?0.75 day^?1 and for sheep was 78.6 kJ kg^?0.75 day^?1. Apparent N digestibility was 17.5% and 0.9% for goats and sheep, respectively, and both species were in negative N balance of 0.25–0.30 g kg^?0.75 day^?1. Total water intake and output were higher in sheep than in goats. Extractable tannins were virtually absent in faeces in both species, however, output of condensed tannins and protein in the ADF and ADL fractions were substantially higher. This showed the presence of tannin-protein complexes in these fractions which explained the negative digestibilities of ADF and ADL. It was concluded that Acacia saligna could not be used as a sole dietary source for small ruminants because of low intake and negative nitrogen balance. This was due mainly to the high tannin content. However, the tree might have a potential as a supplementary fodder due to its high crude protein content.     

Nutritional quality of the blue-green alga Spirulina platensis geitler

The nutritional quality of the blue-green alga Spirulina platensis has been evaluated on the basis of its chemical and amino acid compositions and feeding trials with rats. The protein content of the alga was 58.5%, lysine 4.34 g 100 g^?1 protein, sulphurcontaining amino acids (methionine and cystine) 2.77 g 100 g^?1 protein, and nucleic acids 4%. The true protein digestibility of the alga was found to be 75.5 and its biological value (BV) 68. Supplementation of the alga with methionine (0.2%) resulted in a significant improvement in the BV and net protein utilisation (NPU), but had no effect on true digestibility (TD). TD, BV and NPU were significantly improved when the alga was supplemented with barley (50% nitrogen from both). In Chad and Mexico the alga has been used for centuries as a food. This together with its low cost of production, makes it a suitable source of high quality protein for use as a feed supplement.     

The effect of oat hulls,added to the basal ration for pregnant sows,on reproductive performance,apparent digestibility,rate of passage and plasma parameters

Thirty-five Large White x Landrace sows were housed in individual stalls during gestation and were fed a standard diet (DE, 13.2 MJ kg^?1) supplemented with oat hulls (OH), such that the ratios of basal diet to OH were 1:0, 9:1, 7:3 or 1:1. Digestibility and balance measurements were made during 7-day periods beginning on days 45 and 90 of gestation. During a 3-week lactation all sows were fed a standard diet (calculated DE, 12.5 MJ kg^?1, CP, 152 g kg^?1). Increasing OH intake increased mean net maternal weight gains and P2 fat depths during pregnancy and tended to increase total litter weight at birth. Sow-milk solids content and litter weight gain during the 3-week suckling period also tended to increase (nonsignificant), following increasing OH supplementation during gestation. Increasing OH intake tended to increase VFA and reduce cholesterol concentration in blood plasma at 56 days of gestation. The time taken to consume the once-daily feed allowance increased and gastrointestinal transit time decreased as OH intake increased. The apparent digestibilities of the major nutrients were significantly depressed with increasing levels of OH in the diet but the total amounts of nutrients absorbed increased. The following values were calculated for OH by the difference method: apparent digestibility of DM, 0.31; apparent digestibility of ADF, 0.17; DE, 6.25 MJ kg^?1; ME 6.01 MJ kg^?1.     

The effect of methanal (formaldehyde) treatment of casein on its digestion in vivo and in vitro

The effect of methanal (HCHO) treatment of casein on its in vitro and in vivo digestion was investigated. As the quantity of HCHO bound to casein increased, the in vitro rumen degradability decreased but no further reduction occurred above 10.6 g HCHO kg^?1 treated casein DM. The proportion of the original HCHO (25.4 g HCHO kg^?1 treated casein DM) remaining bound to casein at pH values 3.0 to 6.0 was approximately 0.5; the proportion remaining bound at pH 2.0 was significantly less (0.39). N solubility and in vitro digestion of casein by pepsin/HCl and/or intestinal proteolytic enzymes was significantly reduced by treatment with HCHO (10.6 g HCHO kg^?1 treated casein DM). When fed to rats the dry matter (DM) and true N digestibilities decreased significantly as the ratio HCHO;casein increased; the digestibility of the N-free component of the diet remained unchanged. The quantity of available lysine in the diets and their true biological value (BV) decreased as the level of bound HCHO increased; there was significant linear relationship between BV and available lysine. The apparent disappearances of amino acids from the small intestine of sheep, when untreated or HCHO treated caseins (12.3 g HCHO kg^?1 DM) were infused into the duodenum, were not affected by the pH of the infusate (pH 2.5 or 6.8) but were significantly reduced by HCHO treatment. It is concluded that exposure of HCHO-treated casein to low pH values does not completely release bound HCHO from casein and that the intestinal digestion of casein to which HCHO remains bound is reduced when compared to untreated casein. All amino acids determined showed similarly reduced apparent intestinal absorptions due to HCHO treatment. It is suggested that the lower BV of HCHO-treated caseins was due to reduced metabolic availability of lysine.     

Chemical composition and nutritive value of peach palm (Bactris gasipaes Kunth) in rats

The peach palm (Bactris gasipaes Kunth) is the starchy fruit of a palm tree widely cultivated in Central and South America. The present study aimed at determining its chemical composition and its nutritive value in rats. The average chemical composition of 17 samples was as follows: 410 g kg^?1 water and, in g kg^?1 of dry matter (DM), 54 g crude protein, 114 g oil, 39 g neutral detergent fibre, 716 g starch, 21 g sugars and 18 g ash. The main variability was observed for the oil (60–180 g kg^?1 DM) and starch (590–780 g DM) contents. The proteins contained, on average, in g kg^?1 of proteins, 49 g lysine, 13 g methionine, 19 g cysteine, 39 g threonine and 7 g tryptophan. The mineral fraction contained, per kg DM: 1.0 g Ca, 0.8 g P, 0.6 g Mg, 0.3 g Na, 44 mg Fe, 4 mg Cu and 10 mg Zn. The digestibility of four peach palm genotypes was determined in rats fed a diet composed of 350 g kg^?1 of peach palm and 650 g of a control diet based on maize and soybean meal. The digestibility of DM, energy, starch and protein of peach palm alone reached, on average 91, 87, 96 and 95%, respectively. No difference was observed between varieties, except for starch (p < 0.05). On average, peach palm contained 51 g of truly digestible protein kg^?1 DM and 3.691 kcal digestible energy kg^?1 DM. A growth trial was also carried out for 1 month on rats (initial weight: 78 g) fed a diet containing 0, 200, 400, 600 or 800 g peach palm kg^?1, at the expense of a diet composed of maize starch and casein. The growth rate of the rats decreased (p < 0.05) as the peach palm concentration increased. The growth decrease was due to a decrease (p < 0.05) in DM intake and to the lower quality of the peach palm protein. It is concluded that peach palm is mainly an energy source for humans and animals. It is poor in protein and minerals but can be consumed in large amounts. Copyright © 2005 Society of Chemical Industry     

Digestibility of amino acids in maize,wheat and barley meal,measured in pigs with ileo-rectal anastomosis and isolation of the large intestine

Maize, soft wheat and barley diets were compiled to have similar crude fibre (CF) concentration by addition of purified cellulose. Protein-free diets, with purified cellulose included at 60 g kg^?1 dry matter (DM) (PF1) and 90 g kg^?1 DM (PF2), were formulated. Each of four littermate, male pigs (22 kg liveweight) was surgically modified to create an ileo-rectal anastomosis with complete isolation of the large intestine. Diets were fed, and the ileal digesta, excreted via the anus, were collected. Endogenous amino acid output was higher after feeding PF2 than PF1. The choice of factor for correction of apparent digestibility (AD) to true digestibility (TD) was based upon CF intake of cereal diet. AD of most essential amino acids was greater in wheat than in maize or barley, although AD of lysine in barley (67.1%) was higher than in maize (56.8%) or wheat (63.4%). TD of most essential amino acids was higher for wheat and maize than for barley, although TD of lysine was similar for all cereals. Lysine and threonine were the most poorly digested essential amino acids in all cereals.     

Responses of young chicks to amino acid supplementation of methanol-grown dried microbial cells

Two experiments have been conducted to examine the effects on chick growth and carcass composition of amino acid additions to diets containing spray-dried or flash-dried forms of methanol-grown microbial cells (S-DMC and F-DMC respectively). The spray-dried form was an early development product. An additional factor was the level of total nitrogen (N) in control diets containing soyabean (SBM) and in experimental diets containing 100 g S-DMC or 150 g F-DMC kg^?1 diet. In the first experiment, a diet containing S-DMC supported less growth than the control SBM diet containing equivalent concentrations of total N (39 g kg^?1 DM) and of the sulphur containing amino acids. Supplementation of S-DMC diets containing 36 and 32 g N kg^?1 DM with methionine had no substantial effect on growth or on carcass composition. In the second experiment, methionine supplemented SBM and F-DMC diets containing 43 g N kg^?1 DM elicited similar growth performance and efficiency of food conversion. However, the feeding of basal SBM and F-DMC diets containing sub-optimal concentrations of total N (35 and 36 g N kg^?1 DM respectively) resulted in inferior utilisation of the F-DMC diet, this effect being only partially alleviated by combined dietary supplements of arginine, lysine and methionine.     

Starch but not protein digestibility is altered in pigs fed transgenic peas containing α‐amylase inhibitor

Eighteen individually housed boars were randomly allocated to one of three dietary treatments, an experimental wheat diet containing 989.4 g kg^?1 of a basal wheat diet, or this experimental wheat diet with 500 g kg^?1 of the basal wheat diet replaced with 500 g kg^?1 of either transgenic or non‐transgenic peas. The transgenic peas expressed the bean (Phaseolus vulgaris L.) α‐amylase inhibitor 1 gene. Diets contained n‐hexatriacontane (0.2 g kg^?1) as an indigestible marker to allow the determination of nutrient digestibility at the terminal ileum. Pigs were offered 1.6 kg day^?1 for 15 days, after which they were anaesthetised, the ileal and faecal digesta collected and the pigs subsequently euthanased. The ileal dry matter and starch digestibilities of the experimental wheat, non‐transgenic and transgenic pea diets were 78.3, 74.2 and 45.8% and 95.9, 95.2 and 42.4%, respectively. The apparent nutrient digestibilities of the non‐transgenic and transgenic peas were determined by difference. The ileal dry matter digestibility was significantly reduced in the transgenic peas compared with the non‐transgenic peas (12.7 and 69.9%, respectively; P = 0.006), which was largely due to a reduced starch digestibility. The apparent crude protein digestibilities of the transgenic peas were similar to the non‐transgenic, being 79.7 and 78.5%, respectively. The amino acid digestibilities of the transgenic and non‐transgenic peas were also similar. Copyright © 2006 Society of Chemical Industry