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In this study, we determined whether deficient dietary amino acid (AA) concentrations influence the precaecal (pc) AA digestibility when determined using the regression approach. We mixed two basal diets. Basal diet 1 was deficient in essential AAs, whereas adequate AA concentrations were ensured in basal diet 2 by adding free AAs. Rapeseed cake and full-fat soya beans as test ingredients were included in the basal diets at levels of 100 and 200, and 150 and 300 g/kg, respectively, at the expense of maize starch. Each diet was tested with six replicates of 10 broiler chickens each. The feed intake of the chickens that were fed diets based on basal diet 2 was similar, whereas the feed intake of the chickens that were fed diets based on basal diet 1 differed considerably. The numerical differences in pc AA digestibility determined with basal diet 1 or 2 ranged from 2.6 percentage points to 20.8 percentage points in rapeseed cake and from 0.5 percentage points to 15.2 percentage points in soya beans. Across all measured AAs, the average differences were 10.1 percentage points and 5.4 percentage points in rapeseed cake and soya beans, respectively. The differences in the estimated pc AA digestibility between the basal diets were probably caused by different basal endogenous AA losses in the digesta between treatments as a consequence of different feed intake. Adequate AA concentrations and test ingredient levels that are specifically adjusted to avoid a negative effect on feed intake are recommended for future studies.

1. Herein, it was investigated whether different particle size distributions of feed ingredients achieved by grinding through a 2- or 3-mm grid would have an effect on precaecal (pc) amino acid (AA) digestibility. Maize and soybean meal were used as the test ingredients. 2. Maize and soybean meal was ground with grid sizes of 2 or 3 mm. Nine diets were prepared. The basal diet contained 500 g/kg of maize starch. The other experimental diets contained maize or soybean meal samples at concentrations of 250 and 500, and 150 and 300 g/kg, respectively, instead of maize starch. Each diet was tested using 6 replicate groups of 10 birds each. The regression approach was applied to calculate the pc AA digestibility of the test ingredients. 3. The reduction of the grid size from 3 to 2 mm reduced the average particle size of both maize and soybean meal, mainly by reducing the proportion of coarse particles. Reducing the grid size significantly (P 0.050) increased the pc digestibility of all AA in the soybean meal. In maize, reducing the grid size decreased the pc digestibility of all AA numerically, but not significantly (P 0.050). The mean numerical differences in pc AA digestibility between the grid sizes were 0.045 and 0.055 in maize and soybean meal, respectively. 4. Future studies investigating the pc AA digestibility should specify the particle size distribution and should investigate the test ingredients ground similarly for practical applications.

The objective of the present study was to determine whether there are differences in prececal amino acid digestibility between commonly used slow- and fast-growing broiler strains when the regression approach is applied. ISA J-275 and Ross 308 were selected as common representatives of slow- and fast-growing broiler strains, respectively. The experimental diets with soybean cake at levels of 0, 100, and 200 g/kg were offered for ad libitum consumption between 22 and 29 d post-hatch. Titanium dioxide was used as an indigestible marker. Each treatment was tested with six pens comprising 10 birds each. Digesta samples were collected on a pen basis from the distal two-thirds of the intestine section between Meckel’s diverticulum and 2 cm anterior to the ileocecal-colonic junction. The prececal amino acid digestibility of soybean cake was calculated by linear regression simultaneously for both strains. There was no significant interaction between broiler strain and inclusion level of soybean cake with respect to the prececal CP and amino acid digestibility of complete diets; there was a significant strain effect for 5 out of the 16 measured amino acids. The prececal CP and amino acid digestibility of soybean cake did not differ significantly between strains and was numerically almost identical. The results of the present study provide evidence of the transferability between broiler strains of prececal amino acid digestibility data, determined using the regression approach, thus improving the accuracy of diet formulation without drawbacks.

Interest in amino acid digestibility of feed ingredients for poultry has been keen during the past decade. It is now acknowledged that digestibility determined at the terminal ileum is a better measure of amino acid absorption by the poultry. There had been a proliferation of publications on ileal amino acid digestibility values of range of feed ingredients, but wide variations seen in the published values remain a major concern to the end-users. In addition to the inherent ingredient variation, differences in assay methodology employed in laboratories are important contributing factors, highlighting the need for a consensus standard methodology to determine ileal amino acid digestibility. Two collaborative studies, involving five research stations, were initiated with this aim. In Study 1, maize and rapeseed meal were assayed, and pronounced variations in the ileal amino acid digestibility of these two ingredients were observed when the assay was conducted using station protocols, which differed in assay procedures. Use of a common agreed protocol in Study 2, in which a maize-soybean meal diet was assayed, completely eliminated the variation among research stations in apparent amino acid digestibility estimates. Based on these results, a consensus assay procedure for the determination of apparent ileal amino acid digestibility in feed ingredients for growing birds is proposed. It is hoped that this exercise will enable better comparison of data generated across research stations.

A regression approach was applied to determine the influence of feed provisioning prior to digesta sampling on precaecal (pc) amino acid (AA) digestibility in broiler chickens. Soybean meal was used as an example test ingredient. Five feed-provisioning protocols were investigated, four with restricted provision and one with ad libitum provision. When provision was restricted, feed was provided for 30 min after a withdrawal period of 12 h. Digesta were sampled 1, 2, 4 and 6 h after feeding commenced. A diet containing 300 g maize starch/kg was prepared. Half or all the maize starch was replaced with soybean meal in two other diets. Average pc digestibility of all determined AA in the soybean meal was 86% for the 4 and 6-h protocols and 66% and 60% for the 2 and 1-h protocols, respectively. Average pc AA digestibility of soybean meal was 76% for ad libitum feed provision. Feed provisioning also influenced the determined variance. Variance in digestibility ranked in magnitude 1 h ad libitum 2 h 6 h 4 h for all AA. Owing to the considerable influence of feed-provisioning protocols found in this study, comparisons of pc AA digestibility between studies applying different protocols prior to digesta sampling must be treated with caution. Digestibility experiments aimed at providing estimates for practical feed formulation should use feed-provisioning procedures similar to those used in practice.

Title ofthe paper: The efficiency of utilization of intestinal digestible indispensable amino aeids in growing bulls There are problems to determine the efficiency of protein deposition of intestinal absorbed amino aeids, because it cannot be exeluded that the amount of single or some indispensable amino acid (IAA) can influence the growing Performance of the animal. The dependence of amino acid gain on the flux of essential absorbable amino aeids into the duodenum was studied in growing bulls to calculate the utilization rate of these amino aeids. Four growing bulls (Schwarzbuntes Milchrind, BW: 240–310 kg) with duodenal T-type cannulas were fed diets varying in crude protein content. Energy level was 11,2 MJ ME/kg DM. The efficiency for the different absorbable IAA was decreased with increasing nutritional level. This is in contrast with the constant utilization factor ofthe protein evaluation system (AfB, 1995; 1997). The efficiency of utilization of apparently digestible IAA for protein retention was highest for His and Met and amounted to 33 (He), 34 (Phe and Thr), 38 (Lys and Val), 41 (Leu), 52 (Met) und 76 (His) %, respectively. The intersection ofthe regression curve (AA-deposition against apparently digestible AA) with the abscissae resulted in the maintenance requirement of absorbable amino acid. For growing bulls (BW: 300 kg) a value of 4,7 g/d histidine and 4,2 g/d methionine was determined, but more investigations are necessary in this field.

A rising atmospheric CO2 concentration might affect the nutritional value of feedstuffs. Only little information about the effects of elevated CO2 on C4 plants, such as maize, is known. Therefore, the present study investigated the effects of atmospheric CO2 enrichment on the nutritional value of maize grains (cv. “Romario”), which were grown at two different atmospheric CO2 concentrations (ambient CO2: 380 ppm (AMBI) and enriched CO2: 550 ppm (FACE)) in 2008. The nutrient composition of the maize grains was analyzed and two digestibility studies with pigs (trial 1) and broilers (trial 2), and an in sacco degradability study with cows (trial 3) were performed. Regarding the chemical composition of nutrients, a significant CO2 effect on sugar concentration was observed. The grain sugar concentration increased significantly under CO2 enrichment from 19.9 to 24.8 g kg−1 DM. There were no major effects of the CO2 concentration on the other analyzed nutrients and amino acids. Different results were calculated in both digestibility studies and in the in sacco experiment. The digestibility of the ether extract (EE), organic matter (OM) and the metabolisable energy (ME) for pigs were significantly increased for diet maize grown under FACE conditions. In broiler chickens, the digestibility of crude protein (CP) of the diet containing maize grain cultivated under enriched atmospheric CO2 concentration was significantly increased from 912 to 927 g kg−1 as well as EE, which rose from 914 to 924 g kg−1. The degradability CP and neutral detergent fiber (aNDFom) in the in sacco degradability study were significantly influenced by the CO2 treatment. In both cases, the effective degradability declined significantly from about 730 to 619 g kg−1 (CP) and from 865 to 617 g kg−1 (aNDFom) under FACE conditions at a passage rate of 0.05 h−1. It is concluded that the content of crude nutrients of maize grain cultivated under elevated CO2 did not change, but the digestibility of some nutrients was significantly increased in trials with pigs and broiler chickens and the CP and aNDFom in sacco degradability was significantly decreased.

1. The objectives were to study the variation in amino acid (AA) digestibility of rapeseed meal in laying hens and to investigate whether the variation in AA digestibility can be explained by chemical constituents of the rapeseed meal. Nine rapeseed meals from different processing plants operating in Germany were used. The crude protein and crude fibre concentrations of the meals ranged from 367 to 410 and 137 to 175 g/kg dry matter (DM), respectively. The concentrations of total glucosinolates varied between 5.1 and 12.9 mmol/kg DM. Each meal was included in one of the experimental diets at an inclusion level of 200 g/kg at the expense of maize starch. 2. A total of 16 Lohmann Brown laying hens were used for this experiment and were surgically caecectomised. They were housed individually in metabolism cages. Each of the 10 diets was fed to at least 6 hens in 4 periods of two weeks duration. Excreta were collected during the last 5 d of each period. The digestibility coefficient of AA was calculated for each diet. The digestibility of the rapeseed meals was calculated by multiple linear regression analysis. 3. Mean essential AA digestibility of rapeseed meals varied between 0.78 and 0.84. Among the essential amino acids, the ighest level of digestibility was found for arginine (0.88) and methionine (0.87), and the lowest for lysine (0.74) and threonine (0.75). The highest variation between rapeseed meals in digestibility was found for threonine (0.68 to 0.79) and lysine (0.68 to 0.78). The concentration of neutral detergent insoluble nitrogen of the rapeseed meals was negatively correlated with the digestibility of lysine, but was not significantly correlated with digestibility of any other AA. Glucosinolate concentration was significantly correlated with valine digestibility. 4. Multiple regression analysis showed that the concentrations of crude protein and ash together were the major factors considered to explain variation in digestibility of essential AA. Additional consideration of neutral detergent insoluble nitrogen and total glucosinolates improved the goodness of fit only marginally and was unlikely to be of practical significance.

The objective of this study was to determine the effect of the duration of prefeeding on prececal amino acid (AA) digestibility of wheat distillers dried grains with solubles (DDGS) in broilers. The experimental diets with DDGS at levels of 0, 10, and 20% were offered ad libitum for 7, 5, and 3 d, starting on 14, 16, and 18 d of age. Titanium dioxide was used as an indigestible marker. Six pens of 10 birds were allocated to each treatment. Digesta was sampled on a pen basis from the distal two-thirds of the intestine section between Meckel's diverticulum and 2 cm anterior to the ileo-ceca-colonic junction. Ingested and digested amounts of AA were determined for each pen. Digestibility of AA in the diets was not significantly affected by the duration of prefeeding but was significantly reduced by inclusion of DDGS. Digestibility of AA in DDGS was determined by using a linear regression approach. The digestibility of AA in DDGS ranged from 76% (Arg, 5 d of feeding) to 33% (Asp, 3 d of feeding). There was no significant effect of prefeeding time on AA digestibility of DDGS. Lysine digestibility of DDGS was 72%. The mean digestibility of the AA Arg, Cys, Ile, Leu, Lys, Met, Phe, Thr, and Val of DDGS across the 3 prefeeding times was 66%. This study gave evidence that 3 d of prefeeding a diet is sufficient in studying prececal AA digestibility in broilers when low-digestible feeds are used.

Beet pulp contains high amounts of pectins that can reduce the risk of rumen disorders compared to using feedstuffs high in starch. The objective was to study the effects of inclusion of ensiled pressed beet pulp in total mixed rations (TMR) for high-yielding dairy cows. Two TMR containing no or about 20% (on dry matter (DM) basis) beet pulp silage were used. The beet pulp silage mainly replaced maize silage and corn cob silage. The TMR were intentionally equal in the concentrations of energy and utilisable crude protein (CP) at the duodenum. TMR were fed to 39 and 40 dairy cows, respectively, for 118 days. The average daily milk yield was about 43 kg/day. No significant differences in milk yield and milk fat or milk protein content were detected. DM intake of cows was significantly reduced by the inclusion of beet pulp silage (23.0 v. 24.5 kg/day). However, a digestibility study, separately conducted with sheep, showed a significantly higher organic matter digestibility and metabolisable energy concentration for the TMR that contained beet pulp silage. In vitro gas production kinetics indicated that the intensity of fermentation was lower in the TMR that contained beet pulp silage. In vitro production of short-chain fatty acids, studied using a Rusitec, did not differ between the TMR. However, the inclusion of beet pulp silage in the ration caused a significant reduction in the efficiency of microbial CP synthesis in vitro. The amino acid profile of microbial protein remained unchanged. It was concluded that beet pulp silage has specific effects on ruminal fermentation that may depress feed intake of cows but improve digestibility. An inclusion of beet pulp silage of up to 20% of DM in rations for high-yielding dairy cows is possible without significant effects on milk yield and milk protein or milk fat.

BACKGROUND:Moringa stenopetala is a multipurpose tree which has several agricultural, industrial and medicinal uses. The nutritive value of East African M. stenopetala has not been fully investigated and pertinent data for ruminants are lacking. The present study was therefore conducted to fill this gap by providing the latest information on chemical composition and in vitro fermentation of M. stenopetala tree parts. RESULTS: The respective metabolizable energy values for leaves, seeds and seedpods were 10.0, 7.0 and 5.1 g kg−1 dry matter (DM). The crude protein (CP) contents for leaves, seeds and seedpods were 395, 282 and 110 g kg−1 DM, respectively. For leaves and seeds, 88% and 83%, respectively, of the CP was true protein. Fat contents (g kg−1 DM) were relatively high in seeds (334) but not in leaves (84) or seedpods (110). No starch was detected in seeds. Leaves were a potentially useful source of calcium,, sodium and manganese, containing 18.5, 4.1 and 0.086 g kg−1 DM, respectively. The concentrations of essential amino acids in leaves for leucine, valine, phenylalanine, isoleucine and threonine were 8.5, 5.3, 5.3, 4.5, and 4.4 g 16 g N−1, respectively, and were comparable to those found in soybean and Moringa olifera leaves. The contents of total phenols in seeds and leaves were 1.2 and 56.7 g kg−1 DM, respectively. CONCLUSION: The chemical composition of leaves and seeds from M. stenopetala revealed its potential as a protein and energy supplement for ruminant livestock. Copyright © 2008 Society of Chemical Industry

This study investigated the possibility of using cecectomized laying hens for the determination of amino acid (AA) digestibility of protein sources as an alternative to measurements made at the terminal ileum. Toasted soybeans and corn gluten meal were used as test protein sources. A low-protein basal diet was based mainly on corn, wheat gluten, and cornstarch. In 4 other diets toasted soybeans or corn gluten meal were included each at 15% or 30% at the expense of cornstarch, so that the changes in the AA concentrations of the diets resulted from the protein sources only. Titanium dioxide was used as the indigestible marker. In experiment 1, two hundred ten 18-wk-old pullets were used. Digesta from the posterior 2-thirds of the intestine between Meckel's diverticulum and 2 cm anterior to the ileo-ceca-colonic junction was obtained from killed hens. In experiment 2, fourteen cecectomized hens were used. They were kept individually, and excreta were quantitatively collected. The apparent digestibility of AA was calculated for each diet. Linear regression analysis was used to calculate AA digestibility for the 2 protein sources. Across all diets, apparent AA digestibility was significantly higher in experiment 2 than in experiment 1. However, AA digestibilities of the 2 protein sources were not different between both experiments. Differences in AA digestibility between the protein sources were not significant in experiment 1, but in experiment 2 significant differences between the protein sources were detected for some AA due to a lower standard error of estimate. It was concluded that AA digestibility of protein sources for laying hens can be evaluated based on quantitative excreta collection with cecectomized hens using the regression approach. This needs fewer animals than the determination of digestibility at the terminal ileum. Differences between protein sources are easier to detect because of the lower standard error of estimate.

Summary Four tropical crop seeds, namely Vigna unguiculata (Cowpea), Mucuna pruriens, Manihot esculenta and Centrosema pubescens were thermally processed for 1 h at 100 °C and analysed for their antinutritional factors (ANF). Four hundred and forty-eight 1-day-old broilers were used to determine the effect of heating the seeds on their precaecal crude protein (CP) digestibility. Total phenols, protein precipitable tannins and l-dopa were higher in the mucuna and centrosema seeds and diets than in the vigna and manihot seeds and diets. Phytic acid was of similar occurrence in all the raw seeds. Heat treatment resulted in reduction in all the ANF in the seeds. Precaecal CP digestibility, feed intake and growth rate were significantly (P

It was the objective to compare the digestibility and energy value of fresh grape pomace originating from either white or red wine species. The white grape pomace had higher sugar, but lower fiber concentrations than the red wine pomace. Pomace was mixed with a basal diet and digestibilities were determined with adult wether sheep for the basal diet and the diets containing grape pomace. Faeces were quantitatively collected for 6 days following 14 days of adjustment to the diets. Inclusion of grape pomace in the diet significantly reduced digestibilities and the ME content of the diet, these effects being more pronounced for red grape pomace than for white grape pomace. Digestibilities calculated by difference for the white (and red) grape pomace were 56% (32%) for organic matter, 8% (30%) for crude protein, 19% (6%) for crude fiber, 21% (15%) for neutral detergent fiber, and 7% (0%) for acid detergent fiber. The ME concentration was 8.3 and 5.8 MJ/kg dry matter for white and red grape pomace, respectively. It was concluded that grape pomace can substantially vary in the feeding value for ruminants, depending on the technical details of the wine production process.

Summary Studies on the use of lucerne silage as a forage source for high-yielding dairy cows It was the main objective of this study to investigate effects of lucerne silage inclusion in maize silage-based rations on dry matter intake, milk yield and metabolic parameters of high yielding dairy cows. Three total mixed rations (TMR) were used. They contained as the main forage source on a dry matter basis 41.5% maize silage and 12% grass silage (ration maize) or 18% maize silage and 29% of either grass silage (ration grass) or lucerne silage (ration lucerne). Organic matter digestibility, determined with wether sheep, was 77 and 65% for the grass and the lucerne silage, respectively. Each TMR was fed to 4 wether sheep to determine crude nutrient digestibilities. The content of net energy for lactation (NEL), as calculated from digestible crude nutrients, was (MJ/kg dry matter (DM)): 7.1 (maize), 7.2 (grass) and 6.8 (lucerne). Based on the results of a chemical fractionation of crude protein it was calculated that the content of utilisable crude protein (nXP) was not below 167 g/kg DM and that the N balance in the rumen was not negative for all 3 TMR. The TMR were fed for 169 days to at least 28 dairy cows per treatment which were in their first half of lactation. Feed intake, milk performance data and physiological indicators were measured for each individual cow. The DM intake was significantly higher in treatment lucerne (23.2 kg/d) than in treatments grass (21.2 kg/d) and maize (22.6 kg/d). Daily intakes of NEL and nXP were significantly lower in treatment grass than in the other two treatments. Milk yield was significantly higher in treatment maize (41.7 kg/d) than in treatments grass (37.3 kg/d) and lucerne (38.5 kg/d). This was associated with a significantly lower milk fat content in treatment maize (3.5%) in comparison with the other two treatments (3.9% each). Milk protein content was unaffected by treatment (3.4% on average). Similarly, the acetone content of milk was not significantly different between treatments. The β-hydroxybutyrate content of the deproteinized blood was significantly higher in treatment lucerne at start of lactation, but this difference disappeared in subsequent parts of the experimental period. Measurements of back fat thickness indicated mobilisation and retention of energy by cows during the experimental period to be similar in all treatments. It is concluded that lucerne silage is a suitable forage source for high yielding dairy cows in spite of its low digestibility. Zusammenfassung In dieser Untersuchung sollte geklart werden, wie sich ein Einsatz von Luzernesilage als Alternative zu Grassilage in maisbetonten Rationen auf die Futteraufnahme, die Milchleistung und Stoffwechselparameter von Milchkuhen mit hoher Leistung auswirkt. Daher wurden 3 Mischrationen (TMR) konzipiert, die als wesentliche Grundfutterkomponenten Maissilage in Kombination mit Grassilage (Mais, 41,5 bzw. 12% der Trockensubstanz (T) Mais- und Grassilage) oder (Gras, 18 bzw. 29% der T Mais- und Grassilage) oder Luzernesilage (Luzerne, 18 bzw. 29% der T Mais- und Luzernesilage) enthielten. Die Verdaulichkeit der Organischen Substanz, bestimmt mit Hammeln, betrug fur die Grassilage 77% und fur die Luzernesilage 65%. Die Rohnahrstoffverdaulichkeiten wurden fur die 3 TMR mit Hammeln gemessen und die aus den verdaulichen Rohnahrstoffen berechnete NEL betrug (in MJ/kg T) 7,1 (Mais), 7,2 (Gras) und 6,8 (Luzerne). Auf Basis einer chemischen Rohproteinfraktionierung wurde ermittelt, dass die Gehalte an nutzbarem Rohprotein (nXP) in allen Rationen mindestens 167 g/kg T betrugen und die ruminale N-Bilanz nicht negativ war. Die Rationen wurden uber einen Zeitraum von 169 Tagen an mindestens 28 Milchkuhe je Ration verfuttert. Futterverzehr, Leistungsdaten und Stoffwechselindikatoren wurden tierindividuell erfasst. In der Behandlung Luzerne war der Futterverzehr mit 23,2 kg T/Tag signifikant hoher als in den Behandlungen Gras (21,2 kg T/Tag) und Mais (22,6 kg T/Tag). Die tagliche Aufnahme an NEL und nXP war im Mittel des Versuches in der Behandlung Gras signifikant niedriger als in den beiden anderen Behandlungen. Die tagliche Milchmenge war in der Behandlung Mais (41,7 kg/Tag) signifikant hoher als in der Behandlung Gras (37,3 kg/Tag) und in der Behandlung Luzerne (38,5 kg/Tag), verbunden mit signifikant geringeren Milchfettgehalten in der Behandlung Mais (3,5% im Vergleich zu 3,9% bei Gras und Luzerne). Der Milcheiweisgehalt war nicht von der Behandlung beeinflusst. Der Acetongehalt der Milch war zwischen den Behandlungen nicht signifikant verschieden, in der Behandlung Mais aber tendenziell geringer. Der Gehalt an s-Hydroxybutyrat im Blut war zu Laktationsbeginn in der Behandlung Luzerne signifikant hoher als in den beiden anderen Behandlungen. Dieser Unterschied bestand im weiteren Verlauf der Laktation nicht mehr. Messungen der Ruckenfettdicke deuten einen zwischen den Behandlungen weitgehend ahnlichen Verlauf von Energiemobilisation und -retention im Verlaufe des Versuches an. Daher kann Luzernesilage trotz der relativ geringen Verdaulichkeit auch in Rationen fur Hochleistungskuhe als eine geeignete Grundfutterkomponente angesehen werden.

Three tropical crop seeds, namely Enterolobium cyclocarpum, Mucuna pruriens and Centrosema pubescens, were assessed for their contents of chemical constituents, antinutritional factors (ANFs), crude protein (CP) and amino acid (AA) digestibility. Their meals were incorporated into broiler diets in place of maize starch at two levels (150 and 300 g kg−1). Four hundred and twenty 1-day-old broilers were randomly assigned to seven experimental diets on a weight basis and used to determine CP and AA digestibility in the diets and seeds, and performance of the birds. The CP contents were 237, 278 and 252 g kg−1 DM in E. cyclocarpum, M. pruriens and C. pubescens, respectively. Compared to the basal diet, the digestibility of CP and AAs in the diets and seeds was significantly (p < 0.05) reduced at higher level of inclusion of E. cyclocarpum and M. pruriens but increased at higher C. pubescens inclusion. Digestibility of arginine, threonine and lysine in the C. pubescens meal diets was similar to that in the basal diet. Digestibility values of CP and AAs were least in E. cyclocarpum. Aspartic acid was the least and glutamic acid the most digested AA in all the seeds. Among the essential AAs, threonine was the least digested AA, while leucine (in E. cyclocarpum and M. pruriens) and lysine (in C. pubescens) had the highest digestibility with values of 65, 73 and 72%, respectively. Feed intake, body weights and weight gain in the birds were significantly (P < 0.05) reduced in the E. cyclocarpum and M. pruriens diets but increased in the C. pubescens diets compared to the basal diet. Results of the study suggest that, based on the CP content and AA profiles in the seeds, they have potential for poultry feeding. The presence of ANFs, especially in E. cyclocarpum and M. pruriens, however, could be a major limitation in their use in poultry feeding. Copyright © 2006 Society of Chemical Industry

Measurements of precaecal amino acid digestibility with digesta sampled from slaughtered animals may be affected by the chosen length of the sampled section. The length needs standardization, therefore, when digestibility is understood to be a measure of feedstuff potential. It was our objective to study the change in the net disappearance of amino acids from the lower small intestine of broiler chicken. The section between Meckel's diverticulum and 2 cm anterior of the ileo-caeco-colonic junction was cut into three subsections of equal length: proximal, medial, and terminal. The contents of each subsection were pooled within the birds of each pen (12 in Experiment 1 and 10 in Experiment 2). TiO2 was used as an indigestible marker. Prior to digesta sampling, broilers had been fed the experimental diets for seven days. In Experiment 1, two diets with either soybean meal or a mix of soybean meal and peas as the main protein sources were used. Each diet was allocated to eight pens and feeding commenced on day 14 of age. Net disappearance was significantly affected by diet only in regard to aspartic acid and methionine. No significant interaction between diet and subsection occurred. Net disappearance was significantly affected by subsection for all amino acids. It ranged from 74-92% for individual amino acids without significant differences in the medial and terminal subsections. Net disappearance was, however, between 3% and 9% lower in the proximal subsection. In Experiment 2, diets contained soybean meal as the main protein source and were given to 18 pens from day 22 of age. Again, the effect of subsection on net disappearance was significant for all amino acids. Net disappearance was significantly lower in the proximal than in the middle subsection, and differences ranged from 5-10%. Significant differences in the net disappearance were also found for most of the amino acids between the middle and the terminal subsection ranging from 2-4%. In conclusion, when precaecal amino acid digestibility should be used as a measure for a protein source's potential, digesta sampling should not consider the proximal third of the section between Meckel's diverticulum and the end of the ileum.

The alkane technique allows estimates of intake and diet composition. For the latter a correction for incomplete recovery of faecal alkane concentrations has to be made. Feeding level and diet proportions have been discussed as factors possibly influencing recovery. A balance trial was conducted to study these effects on faecal alkane recovery rates and their consequences on estimates of roughage intake in sheep. The diets consisted of force-dried pelleted alfalfa meal (A) and wheat whole meal (W) in three levels each (360, 480, 600 and 270, 360, 450 g/day, respectively); the wheat was partly labelled with beeswax to provide a distinctive alkane pattern. Each diet was fed to four wethers. Despite significant effects (P

The amount of crude protein entering the small intestine (nXP) and the nitrogen balance in the rumen (RNB) are the two components of the German protein evaluation system. Although there is no scientific evidence, feeding strategies for the practice imply an excess in RNB, particularly in diets for high-yielding cows. This study was undertaken to investigate whether cows benefit from an excess in RNB under conditions of sufficient nXP supply. Three rations were used equal in energy (7.2 MJ net energy for lactation per kilogram dry matter; DM) and nXP (173 g/kg DM) and mainly based on silages from maize, grass, and brewer's grains as well as ground barley and solvent extracted meals from rapeseed and soybeans. Three rations were calculated to allow for an RNB of either 0 or 50 g/day. RNB was adjusted by either a supplementation of urea or a change in the proportions of oilseed meals. The intended levels of energy, nXP and RNB in the diets were confirmed under consideration of separate digestibility measurements with wether sheep and a chemical fractionation of dietary crude protein. The rations were offered as total mixed rations. At least 35 cows between days 21 and 98 of lactation were used per treatment. Cows were milked three times daily and had continuous access to feed and water. Feed intake was measured continuously and for each cow individually by a feeder system through which the rations were offered. The average values for the three treatments ranged between 20.1 and 21.7 kg/day for DM intake, 43.0 and 44.0 kg/day for milk yield, and 1.39 and 1.42 kg/day for milk protein yield. No significant treatment effect was detected in any of the monitored criteria. Cows were in a negative energy budget as indicated by a loss in backfat thickness, similar for all treatments. Under inclusion of literature data it is concluded that under conditions of a sufficient nXP supply, dairy cows do not need an excess in RNB in total mixed rations, even at very high levels of milk protein yield.

1. Caecectomised laying hens were used in two assays to study the effects of a microbial 6-phytase on amino acid (AA) digestibility and energy metabolisability using (1) diets with phytate-rich protein sources and (2) with two dietary phosphorus (P) levels. The two assays followed a 2 x 2-factorial arrangement of treatments using 8 hens per treatment. The hens were housed individually in metabolism cages, and excreta were quantitatively collected for a period of 5 d. 2. In Assay 1, two dietary P levels (8.0 and 4.0 g/kg dry matter) and two levels of phytase supplementation (0 and 1000 U/kg diet) were used in diets that were mainly based on maize, sunflower meal and wheat gluten. The digestibility of AA was 001 to 002 lower in the diet with the low P than with the high P concentration. The effect of P content was significant for 12 out of the 14 AA studied. The supplementation of phytase significantly improved the degradation of myo-inositol(1,2,3,4,5,6)hexakisphosphate (IP6), but affected neither AA digestibility nor energy metabolisability. An interaction between the two factors was not detected. 3. In Assay 2, diets contained one main protein source (sunflower meal or rapeseed meal) at a concentration of 250 g/kg. The diets were either supplemented or not with phytase (1500 U/kg diet). On average, AA digestibility was 0.01 lower in the rapeseed meal-containing diet than in the sunflower meal-containing one. The maximum difference was 0.03. The effect of the protein source was significant for 9 of the 14 AA studied. The supplementation of phytase had no significant effect on AA digestibility or energy metabolisability. 4. Our studies do not substantiate the hypothesis that improved IP6 degradation due to phytase supplementation is associated with improved AA digestibility and energy metabolisability in laying hens. An interaction between phytase efficacy to improve AA digestibility or energy metabolisability and the P level in the diet does not seem to exist.

The objective of this study was to determine the inevitable endogenous amino acid (AA) loss at the terminal ileum of broilers that were fed diets with 2 different fiber levels using a regression approach. The design of the study was a randomized complete block employing a factorial arrangement of treatments with 3 CP levels (50, 90, and 130 g/kg) and 2 fiber levels. The fiber level was adjusted by inclusion of cellulose at the expense of cornstarch. The AA pattern of the CP was the same in all diets. Titanium dioxide was used as indigestible marker. Six cages of 8 birds were allocated to each diet. The experimental diets were offered for ad libitum consumption for 3 d, starting on 21 d of age. Digesta were sampled on a cage basis from the distal two-thirds of the intestine section between Meckel's diverticulum and 2 cm anterior to the ileo-ceca-colonic junction. Inevitable endogenous CP and AA losses were determined by extrapolating the linear regressions between intake and prececal flow toward zero intake. The inevitable losses of CP and AA, expressed in relation to DM intake, were significantly increased by increased cellulose inclusion in the diet. Amino acids with the greatest loss were Glu, Asp, and Thr, whereas Met was the AA with the lowest loss. The ranking of the concentrations of AA of inevitable CP loss was very similar between the 2 fiber levels. This ranking also was similar in comparison to published values for the endogenous AA losses in broilers. It was concluded that the fiber level in the diet can affect the amount of AA inevitably lost at the terminal ileum and that all AA are affected to a similar extent. The results suggest that there is no effect of enhanced fiber level in the diet on AA composition of prececal endogenous CP loss in broilers. These findings can be considered in modeling the AA requirements of broilers.

Summary The objective was to study whether thermally treated lupins (TTL) can replace solvent-extracted soybean meal (SBM) and rapeseed meal (RSM) in dairy cow rations. Three total mixed rations (TMR) were used. They differed in the inclusion of the main protein feeds (TTL alone, TTL + RSM and RSM + SBM) but were equal in organic matter digestibility and metabolizable energy content. In vitro organic matter fermentation was not significantly different between the TMR. Efficiency of microbial crude protein (MCP) synthesis was significantly higher for TMR RSM + SBM than for TTL. In vitro gas production potential was similar for the three TMR. The maximal rate of gas production was achieved later in TMR TTL than in RSM + SBM. Feed intake of dairy cows was significantly lower when TMR TTL was fed than when TMR TTL + RSM or RSM + SBM were fed. Milk yield was significantly lower with the high inclusion rate of TTL in comparison with the other TMR. The contents of milk protein and milk fat were significantly lower when the two TTL containing TMR were fed in comparison with the RSM + SBM ration. Effects of TTL inclusion on MCP synthesis may affect the amino acid supply to the duodenum of cows to a greater extent than differences in the degradability of feed proteins.

The objective of this study was to compare prececal amino acid (AA) digestibilities in broilers, turkeys, and Pekin ducks that were 3 wk old. Five diets were used: a basal diet and diets that contained either soybean meal (SBM) or rapeseed meal (RSM) at the expense of starch each at either 150 or 300 g/kg. The differences in dietary CP and AA concentrations resulted only from the inclusion of SBM or RSM. Titanium dioxide was used as an indigestible marker. Each diet was allocated to 6 pens of 12 birds from each species and provided ad libitum for 1 wk starting at 14 d of age. Digesta were sampled on a pen basis from the distal two-thirds of the section between Meckel's diverticulum and 2 cm anterior to the ileocecocolonic junction. Ingested and digested amounts of AA were determined for each pen. Digestibilities for the 2 meals were then determined by a multiple linear regression analysis, which makes a correction for basal endogenous AA losses unnecessary. Digestibilities for essential AA from the meals varied between 92% (Met, RSM, broilers) and 62% (Val, RSM, ducks). Digestibilities were not significantly different between SBM and RSM for broilers and turkeys, but the average digestibility across all AA was slightly higher for SBM and lower for RSM in turkeys than in broilers. Digestibilities were lower in ducks than in the 2 other species, and significant differences between SBM and RSM were detected for some AA in ducks. Amino acid digestibility ranking was very similar between broilers and turkeys but different for the 2 meals. It was concluded that differences among species cannot be explained by differences in basal endogenous AA losses among species. Amino acid digestibilities determined with broilers should not be used in formulating feed for ducks.

The objective was to study the variation in the amino acid profile of microbial fractions obtained after feeding 16 total mixed rations for dairy cows in a Rusitec. Each ration was incubated for 15 d in 3-fold replicate. The rations showed high variation in the inclusion level of different ingredients and the content of proximal nutrients, fiber fractions, and energy. Three microbial fractions were isolated by centrifugation. The reference microbes (RM) were isolated from the liquid effluent of vessels between d 7 and 15 of incubation. Solid-associated microbes (SAM) were detached with methylcellulose from feed residues after incubation, and liquid-associated microbes (LAM) were obtained from the liquid content of the vessel. Both SAM and LAM were obtained only once for each vessel at the end of the incubation period. Across all rations, significant differences were found between RM, LAM, and SAM in amino acid concentration for some, but not all, amino acids. Within each microbial fraction, significant differences in the content of amino acids were found between rations. Multiple linear regression analysis did not show that the content of a certain nutrient or the inclusion rate of single feedstuffs could be used to predict the amino acid profile of microbial protein with an adequate level of accuracy. Further studies are necessary before the supply of individual microbial amino acids to the cows' duodenum can be modeled and predicted in dependence of diet data.

Studies on the use of lucerne silage as a forage source for high-yielding dairy cows. It was the main objective of this study to investigate effects of lucerne silage inclusion in maize silage-based rations on dry matter intake, milk yield and metabolic parameters of high yielding dairy cows. Three total mixed rations (TMR) were used. They contained as the main forage source on a dry matter basis 41.5% maize silage and 12% grass silage (ration maize) or 18% maize silage and 29% of either grass silage (ration grass) or lucerne silage (ration lucerne). Organic matter digestibility, determined with wether sheep, was 77 and 65% for the grass and the lucerne silage, respectively. Each TMR was fed to 4 wether sheep to determine crude nutrient digestibilities. The content of net energy for lactation (NEL), as calculated from digestible crude nutrients, was (MJ/kg dry matter (DM)): 7.1 (maize), 7.2 (grass) and 6.8 (lucerne). Based on the results of a chemical fractionation of crude protein it was calculated that the content of utilisable crude protein (nXP) was not below 167 g/kg DM and that the N balance in the rumen was not negative for all 3 TMR. The TMR were fed for 169 days to at least 28 dairy cows per treatment which were in their first half of lactation. Feed intake, milk performance data and physiological indicators were measured for each individual cow. The DM intake was significantly higher in treatment lucerne (23.2 kg/d) than in treatments grass (21.2 kg/d) and maize (22.6 kg/d). Daily intakes of NEL and nXP were significantly lower in treatment grass than in the other two treatments. Milk yield was significantly higher in treatment maize (41.7 kg/d) than in treatments grass (37.3 kg/d) and lucerne (38.5 kg/d). This was associated with a significantly lower milk fat content in treatment maize (3.5%) in comparison with the other two treatments (3.9% each). Milk protein content was unaffected by treatment (3.4% on average). Similarly, the acetone content of milk was not significantly different between treatments. The beta-hydroxybutyrate content of the deproteinized blood was significantly higher in treatment lucerne at start of lactation, but this difference disappeared in subsequent parts of the experimental period. Measurements of back fat thickness indicated mobilisation and retention of energy by cows during the experimental period to be similar in all treatments. It is concluded that lucerne silage is a suitable forage source for high yielding dairy cows in spite of its low digestibility.

An experiment was conducted to study the variation in the precaecal amino acid (AA) and energy digestibility of 4 cultivars of white-flowering peas (Pisum sativum) for broiler chickens. The 4 cultivars were grown and harvested under the same agronomic and environmental conditions. One basal diet and 8 diets including each pea cultivar at inclusion rates of either 150 or 300 g/kg were used. Peas were included at the expense of starch. Hence, the differences in dietary crude protein and AA concentrations resulted only from the inclusion of peas. Titanium dioxide was included as an indigestible marker. Crude protein concentrations in the complete diets ranged from 164 to 244 g/kg. All diets were fed ad libitum to broiler chickens between 14 and 21 d of age. Seven pens of 12 chickens were allocated to each treatment. Digesta were sampled on a pen basis from the section of the gastrointestinal tract between Meckel's diverticulum and 2 cm anterior to the ileo-caeco-colonic junction. The proportions of crude protein and AAs digested responded linearly to increased intake and the relationships between quantitative intake and digested amounts of AAs were described by multiple linear regressions. The slope determined for each pea cultivar was taken as a measure of AA digestibility without the need for consideration of basal endogenous crude protein and AA secretions. Digestibility of AAs in peas ranged from 0.60 to 0.91. One cultivar had significantly lower AA digestibilities than the other three cultivars. This could be explained neither by the trypsin inhibitor activity nor by tannin levels. The AAs with the highest digestibilities in all cultivars were arginineglutamic acidlysinemethioninephenylalanineleucine. The AAs with the consistently lowest digestibilities were cystinethreonine. The ranking of the remaining AAs varied slightly between cultivars. The multiple linear regression approach is suitable to study differences in AA digestibilities without the need for consideration of basal endogenous AA losses. Diets containing 300 g/kg of peas had significantly lower energy digestibilities than the pea-free basal diet. The pea cultivar with the lowest AA digestibility caused the lowest energy digestibility at both levels of pea inclusion.

The aim of the present study was to determine equations that predict ME in total mixed rations (TMR) based on routine methods. The ME content of 30 TMR for dairy cows was determined based on digestible crude nutrients obtained with wether sheep. Concentrations in the TMR (in g/kg DM) varied between 118 and 234 for crude protein, 26 and 48 for crude lipid, 131 and 250 for crude fibre, 281 and 488 for NDF, and 173 and 304 for ADF. Gas production ranged from 40.7 to 54.1 ml/200 mg DM, and enzymatically degraded organic matter from 652 to 800 g/kg DM. Digestibility [%] ranged from 68.6 to 84.0 for organic matter, from 55.6 to 84.3 for crude lipid, from 55.0 to 77.8 for crude fibre, from 57.6 to 77.0 for NDF and from 53.1 to 79.6 for ADF. ME ranged from 9.6 to 11.9 MJ/kg DM, and NEL from 5.7 to 7.4 MJ/kg DM. ME content was highly correlated with the concentration of both crude fibre and enzymatically degradable organic matter as well as with organic matter digestibility. A multiple regression equation based on crude fibre and crude lipid predicted ME with a reasonable goodness of fit (r2 = 0.81; s(y.x) = 2.4%). The inclusion of other nutrients, of neutral and acid detergent fibre, neither of gas production did improve the goodness of fit. The best prediction was achieved with inclusion of enzymatically degraded organic matter (r2 = 0.90; s(y.x) = 1.7%).

The amount of crude protein entering the small intestine (nXP) and the nitrogen balance in the rumen (RNB) are the two components of the German protein evaluation system. Although there is no scientific evidence, feeding strategies for the practice imply an excess in RNB, particularly in diets for high-yielding cows. This study was undertaken to investigate whether cows benefit from an excess in RNB under conditions of sufficient nXP supply. Three rations were used equal in energy (7.2 MJ net energy for lactation per kilogram dry matter; DM) and nXP (173 g/kg DM) and mainly based on silages from maize, grass, and brewer's grains as well as ground barley and solvent extracted meals from rapeseed and soybeans. Three rations were calculated to allow for an RNB of either 0 or 50 g/day. RNB was adjusted by either a supplementation of urea or a change in the proportions of oilseed meals. The intended levels of energy, nXP and RNB in the diets were confirmed under consideration of separate digestibility measurements with wether sheep and a chemical fractionation of dietary crude protein. The rations were offered as total mixed rations. At least 35 cows between days 21 and 98 of lactation were used per treatment. Cows were milked three times daily and had continuous access to feed and water. Feed intake was measured continuously and for each cow individually by a feeder system through which the rations were offered. The average values for the three treatments ranged between 20.1 and 21.7 kg/day for DM intake, 43.0 and 44.0 kg/day for milk yield, and 1.39 and 1.42 kg/day for milk protein yield. No significant treatment effect was detected in any of the monitored criteria. Cows were in a negative energy budget as indicated by a loss in backfat thickness, similar for all treatments. Under inclusion of literature data it is concluded that under conditions of a sufficient nXP supply, dairy cows do not need an excess in RNB in total mixed rations, even at very high levels of milk protein yield.

The effect of a continuous duodenal infusion of L-histidine (His) (8 g/d) on the retention of nitrogen was investigated in two experiments (I, II), each of which was carried out using two young bulls. In Exps. I and II, the animals (150-250 kg BW) were fitted with a re-entrant cannula in the proximal duodenum and were fed diets containing 125 g CP/kg DM and 11.5 MJ ME/kg DM. A third experiment (III) using two young bulls (140-200 kg BW) fitted with a simple T-cannula was carried out infusing 6 g L-His. The animals were fed a low protein diet (94 g CP/kg DM and 11 MJ ME/kg DM). The study was done to find out whether or not L-His is the first limiting amino acid (AA) for growing ruminants. N retention was 28 and 31, 38 and 38, 22 and 24 g/d without L-His infusion and with L-His infusion for Exps. I, II and III, respectively. Both in the experiments with a standard protein supply (I, II) and in the experiment with reduced protein supply (III), no significant differences were found between periods with and without infusion of L-His. The utilisation of duodenal NAN varied between 39% and 50% and was also not significantly influenced by the duodenal infusion of L-His. No significant effect was observed on the flow of AA into the duodenum. The faecal excretion of AA was also not significantly influenced by the infusion of L-His. The utilisation of individual amino acids as calculated by the ratio of retained AA to intestinal apparently digested AA, did not differ significantly following the duodenal infusion of L-His. As expected, the utilisation of His decreased. Of the different essential AA, L-His was the most utilised (80%) followed by Arg (72%), Met (60%), Leu (45%) and Lys (44%), during periods without supplementation of L-His. It is concluded that the intestinal supply of L-His from the basal diet was sufficient for the potential growth level of animals under these experimental conditions. In all AA present at the proximal duodenum, L-His could have at first a limiting effect on the performance of growing young bulls with high body gain. Arg and Met, but not Lys, could be second or co-limiting AA.

There is a growing interest in the use of lesser known plant seeds as sources of protein in monogastric feeding in the tropics. It is thought that the exploitation of novel seeds which are currently not utilized by man can contribute to the amelioration of the insufficient feed supply situation in tropical countries like Nigeria. The seeds of Manihot esculenta (Cassava) have the potential to complement the conventional plant protein in poultry diets. Lack of information on the nutritional quality and digestibility of the protein and amino acids in the seeds has caused a limitation in their use for poultry feeding. The objectives of this study were 1) to investigate the chemical and antinutritional constituents in the seeds of Manihot esculenta, and 2) to determine the precaecal digestibility of crude protein (CP) and amino acids (AAs) in the seeds with broilers and their effect on the performance of the birds.

The efficacy of three microbial phytases to increase the amount of digestible phosphorus (dP) was studied in pigs. A basal diet was prepared meeting the requirements of 30-kg pigs with the exception of P. Concentrations (in g/kg dry matter) were: P 2·9, phytate P 1·3, calcium (Ca) 6·9, and crude protein 208. Intrinsic phytase activity was below detection limit. Microbial phytase was supplemented from three sources (Aspergillus niger (Asp), Peniophora lycii (Pen), and consensus phytase (Con)) at the following levels (phytase units (FTU) per kg diet): 150, 300, 450, 600 and 900. Diets were pelleted without steam. Forty-eight male castrated crossbred pigs ((Large White X German Landrace) X Pietrain) initially weighing, on average, 28 kg were individually penned. Each of the 16 diets was offered to three pigs in three consecutive periods of 17 days each, resulting in nine replicates per treatment. No animal received the same diet twice. Faeces were spot-sampled for each individual pig twice daily for the last 7 days of each period. TiO2was used as an indigestible marker. An exponential function was fitted to the data, and both marginal and cumulative efficacies of phytases were described on the basis of the resulting functions.No significant period effect was detected for any of the obtained data. On overall average, daily live-weight (LW) gain was 730 g, and 2.57 kg food were needed per kg LW gain. Neither criterion was significantly affected by source or level of supplementary phytase. Digestibility of organic matter and crude protein averaged 0.90 and 0.84, respectively, again without a significant treatment effect. Digestible P concentration in no case exceeded 1.5 g/kg DM, indicating that P supply to pigs was marginal in all treatments. Digestibility of P from the basal diet was 0.22. P digestibility was significantly affected (P = 0.001) both by the source and by the level of supplementary phytase. It responded in a non-linear fashion to increasing phytase supplementation, this course being less clear for Pen than for Asp and Con phytase. In no case was a clear plateau in P digestibility reached within the range studied. For Asp and Con, marginal efficacy decreased from about 2 mg dP per incremental FTU at low supplementary level to roughly 0.6 mg dP per incremental FTU. This clear dose dependent effect was not present for the Pen phytase, where about 0.6 to 0.7 mg dP per incremental FTU were released almost irrespective of the level of supplementation. It is concluded that phytases of different origin rank differently from each other regarding their efficacy, depending on the level of supplementation. Dose-response studies are recommended in cases where different phytases are to be compared.

The goal of this study was to identify dietary factors that affect fermentation and efficiency of microbial crude protein (CP M ) synthesis in the rumen in vitro. We used 16 total mixed, dairy cow rations with known digestibilities that varied in ingredient composition and nutrient content. Each ration was incubated in a Rusitec (n = 3) for 15 d, and fermentation of different fractions was assessed. Observed extents of fermentation in 24h were 35 to 47% for organic matter, 25 to 60% for crude protein, 3 to 28% for neutral detergent fiber, and 31 to 45% for gross energy. Organic matter fermentation depended on the content of crude protein and neutral detergent fiber in the ration. We studied net synthesis of CP M using an 15 N dilution technique and found that 7 d of continuous 15 N application are needed to achieve an 15 N enrichment plateau in the N of isolated microbes in this type of study. The efficiency of CP M synthesis was 141 to 286 g/kg of fermented organic matter or 4.9 to 11.1 g/MJ of metabolizable energy, and these ranges agree with those found in the literature. Multiple regressions to predict the efficiency of CP M synthesis by diet data showed that crude protein was the only dietary chemical fraction that had a significant effect. Fat content and the inclusion rate of corn silage in the ration also tended to improve efficiency. We suggest that microbial need for preformed amino acids may explain the crude protein effect. A large part of the variation in efficiency of microbial activity still remains unexplained.