Endogenous Crude Protein Research Articles

Characterization of ruminal degradation, intestinal digestion and total true nutrient supply to dairy cows from feedstocks and coproducts from Canola bio-oil processing: Impact by source origin.

The objective of this study was to characterize ruminal degradation, intestinal digestion and total true nutrient supply to dairy cows from canola feedstock (canola seeds) and coproducts (meal and pellets) from bio-oil processing which were impacted by source origin. The feedstocks and coproducts (mash, pellet) were randomly collected from five different bio-oil processing plants with five different batches of samples in each bio-processing plant in Canada (CA) and China (CH). In situ rumen degradation kinetics were determined using four fistulated Holstein cows with incubation times at 0, 2, 4, 8, 12, 24 and 48 h. Intestinal digestions were determined using the three-step in vitro method with preincubation at 12 h. The DVE/OEB and National Research Council systems were applied to evaluate the truly absorbable nutrient supply to dairy cows and feed milk values (FMVs). The results showed that in situ undegradable fractions (U) (p = 0.025) were higher in CA meals, and potentially degradable fraction of D was higher (p = 0.016) in CH meals. CH meals had higher total digestible dry matter (TDDM, p = 0.018) and intestinal digestibility of protein (dIDP, p = 0.016). Canola meals from CA had lower MREE (microbial protein synthesized in the rumen based on available rumen degradable protein; p = 0.011) and DVME (rumen synthesized microbial protein digested in the small intestine; p = 0.011) and had higher ECP (endogenous protein in the small intestine, p = 0.001) and absorbed endogenous crude protein (truly absorbed ECP in the small intestine) than CH (p = 0.001). The FMV evaluated based on the metabolic protein and net energy showed no differences between CA and CH in both coproducts and feedstocks.

True and standardized ileal digestibilities and specific ileal endogenous recoveries of crude protein and amino acid in soybean meal, rapeseed meal and peas fed to growing pigs

A digestibility study was conducted to investigate true (TID) and standardized (SID) ileal digestibilities and specific ileal endogenous recoveries of crude protein (CP) and amino acids (AA) in pigs fed cornstarch-based assay diets with soybean meal, rapeseed meal or peas. The TID and total ileal endogenous CP and AA recoveries were determined using the homoarginine (Harg) method. Six barrows (German Landrace×Pietrain) with an initial body weight of 19±1.8kg, and fitted with ileal T-cannulas were fed the assay diets according to a double 3×3 Latin Square design. The assay diets were formulated to contain 180g CP/kg (as fed basis). Ileal digesta were collected continuously for 24h to determine SID values on days 6 to 8 and for 12 h to determine TID values on days 9 to 10 of each experimental period. The TID and total ileal endogenous recoveries were determined by feeding assay diets with 50% of the dietary protein source guanidinated to convert Lys to Harg for direct determination of TID of Lys. Total ileal endogenous Lys and CP recoveries (g/kg DMI) were highest (P<0.05) in ileal digesta of pigs fed the pea compared to the rapeseed meal or soybean meal assay diets. By contrast, recoveries of specific ileal endogenous CP and most AA (g/kg DMI) in the assay feed ingredients were higher in soybean meal compared to rapeseed meal (P<0.05) and intermediate for peas (P>0.05). The TID of CP and AA were the lowest (P<0.05) in rapeseed meal compared to soybean meal or peas. The lowest SID of CP and indispensable AA were observed in rapeseed meal, with intermediate values for peas, and highest values in soybean meal (P<0.05). As specific ileal endogenous recoveries differ among feed ingredients, these losses should be considered explicitly in addition to SID values to account for the metabolic costs associated with the intestinal synthesis and recycling of endogenous CP and AA.

Chemical composition and standardised ileal digestibilities of crude protein and amino acids in grain legumes for growing pigs

The study was conducted to determine chemical composition and standardised ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) in currently available grain legume cultivars for growing pigs. Three consecutive experiments were conducted with six barrows each, fitted with simple ileal T-cannulas. In total, 18 assay diets including six different cultivars of faba beans ( Vicia faba) and peas ( Pisum sativum), respectively, five different cultivars of lupins ( Lupinus luteus, Lupinus angustifolius) and one assay diet with a commercial soybean meal (SBM, 490 g kg − 1 CP as-fed) were fed according to a row-column-design. The assay feed ingredients were added to a corn starch casein-based basal diet at the expense of corn starch. Each diet was formulated to supply approximately 50% of CP and AA from the assay feed ingredient and casein, respectively. Furthermore, the basal ileal endogenous losses and SID of CP and AA in casein were estimated by regression analysis from apparent ileal digestible and total dietary contents of CP and AA. The SID of CP and AA in the grain legumes were determined in difference to SID of CP and AA originating from casein, after correcting the apparent ileal digestibilities (AID) of CP and AA in the assay diets for basal ileal endogenous CP and AA losses. The average SID of CP in faba bean cultivars (76%) and pea cultivars (79%) were lower compared to lupin cultivars (87%) and SBM (87%) ( P < 0.05). The SID of all AA in faba bean cultivars were lower compared to lupin cultivars and SBM ( P < 0.05). Digestibility values measured in the present study provide further information to accurately formulate diets for pigs based on standardised ileal digestible contents of CP and AA in currently available grain legumes for growing pigs.

Parâmetros ruminais e síntese de proteína metabolizável em bovinos de corte sob suplementação com proteinados contendo diversos níveis de proteína bruta

Avaliaram-se os efeitos dos níveis de nitrogênio de suplementos proteicos sobre as concentrações de nitrogênio amoniacal (N-NH3) e ácidos graxos voláteis (AGV) e o pH em bovinos de corte em pastagem de capim-marandu (Brachiaria brizantha, cv. Marandu). Foram realizadas estimativas da síntese microbiana, do aporte de proteína nãodegradável no rúmen (PNDR) e proteína endógena e das suas contribuições no pool de proteína metabolizável (PM). Quatro bovinos Nelore com 395 ± 9 kg, fistulados no rúmen, foram utilizados nas medidas dos parâmetros ruminais e nas avaliações da degradabilidade, da cinética ruminal e das estimativas de síntese microbiana em um delineamento quadrado latino 4 ×4. Suplementos com 30, 40 ou 50% de proteína bruta (PB) foram fornecidos na quantidade de 400 g/animal.dia para comparação a um grupo controle, sem suplementação proteica. Os animais foram mantidos em pastagens de Brachiaria brizantha, cv. Marandu, distribuídos em quatro piquetes com área de 1,0 ha cada, com oferta do suplemento e retirada das sobras, realizada diariamente. As concentrações de N-NH3 nos animais que receberam o suplemento com 50% PB foram superiores às observadas naqueles sob suplementação com 40% PB e no grupo controle, mas foram semelhantes às observadas no grupo sob suplementação com 30% PB. As concentrações de AGV no grupo sob suplementação com 30% PB foram superiores às observadas no grupo controle e semelhantes às obtidas com suplementação com 40 e 50% PB. O pH não diferiu entre os grupos. A estimativa de oferta de proteína microbiana e de PNDR foi maior para os animais sob suplementação com proteína em relação à observada no grupo controle.

The Concept of Standardized Ileal Amino Acid Digestibilities: Principles and Application in Feed Ingredients for Piglets

In this review, the terminology that is used to describe ileal amino acid (AA) digestibilities in piglet feed ingredients is defined. If one accepts that the determination of AA digestibilities should be based on the ileal analysis method, one should consider that ileal digesta contains variable amounts of endogenous crude protein (CP), which originates mainly from digestive secretions, sloughed-off epithelial cells and mucins. The ileal endogenous CP and AA losses are separated into basal ileal endogenous CP and AA losses (IAAL B ), which are not influenced by the feed ingredient composition, and specific ileal endogenous CP and AA losses (IAAL S ), which are induced by feed ingredient characteristics such as level and type of fiber and anti-nutritional factors (ANF). Depending how ileal endogenous CP and AA losses are considered in the measurement of CP and AA digestibilities, digestibility values are expressed as apparent (AID), standardized (SID), or true (TID) ileal digestibilities of CP and AA. The main concern associated with the use of AID values in diet formulation for pigs is that they are not additive in mixtures of feed ingredients. Consequently, the concept of standardized ileal CP and AA digestibilities was introduced by correcting AID values for basal ileal endogenous CP and AA losses (IAAL B ). The correction for both IAAL B and IAAL s yields TID values, however, routine procedures to measure IAAL s are not yet available. In principle, SID values should be preferred, because they represent the fundamental properties of the feed ingredient. There exist only few reports on SID of CP and AA in feedstuffs frequently used in piglet nutrition. These include soybeans (SB), soybean meal (SBM), soy proteins (SP), soy protein concentrate (SPC), soy protein isolate (SPI), corn gluten (CG), wheat gluten (WG), pea protein (PeaP), potato protein (PotP), fish meal (FM) and whey proteins (WP), but the results obtained are inconsistent. Differences in SID values within feed ingredients may, at least in part, be attributed to different processing conditions or inherent differences of the assay feed ingredients. Moreover, there is some evidence that the determination of SID values and IAAL B in piglets may be confounded by the dietary CP level of the assay diet, age and (or) body weight (BW), the level of feed intake or the methodological approach used to determine IAAL B .

Effect of dietary crude protein level on basal ileal endogenous losses and standardized ileal digestibilities of crude protein and amino acids in newly weaned pigs

The study was carried out to estimate basal ileal endogenous crude protein and amino acid losses (IAAL(B)) and standardized ileal digestibilities (SID) of crude protein (CP) and amino acids (AA) originating from casein in newly weaned pigs from linear relationships between ileal recoveries and dietary intakes of graded levels of CP and AA. A total of 14 (12 + 2 for replacement) 3-week-old barrows weighing 5.7 kg was fitted with simple T cannulas at the distal ileum. At 28 days of age, the pigs were randomly allocated to the six experimental diets with two pigs per diet in four weekly repeated measurements. Corn starch-based diets, containing six graded levels of CP from casein (90, 155, 220, 285, 350, 415 g/kg CP as-fed basis respectively), were formulated. Titanium dioxide (TiO(2)) was included as a digestibility marker. Each experimental period consisted of 7 days. Ileal digesta were collected for a total of 24 h during day 6 and 8. Splitting the total range of 90 to 415 g/kg CP into smaller ranges, i.e. from 90 to 220, 220 to 350 or 285 to 415 g/kg CP, provides estimates for CP and AA recoveries which are not significantly different from zero. As a result, dietary CP and AA originating from casein are completely digested and absorbed until the end of the small intestine. In addition, the use of large ranges of dietary CP levels showed that IAAL(B) were affected (p < 0.050) by the dietary CP content. Accepting that ileal recoveries of CP and AA are exclusively of endogenous origin when purified corn starch casein-based diets are fed, IAAL(B) were estimated as a function of the dietary CP level. There were linear increases (p < 0.050) in IAAL(B) when the dietary CP content was increased from 90 to 415 g/kg. Average IAAL(B) expressed in g/kg dry matter intake (DMI) were 16.3, 0.7, 0.2, 0.9 and 0.2 for CP, lysine, methionine, threonine and tryptophan respectively. These values are in close agreement with IAAL(B) obtained in grower-finisher pigs.

Estimates of basal ileal endogenous losses of amino acids by regression analysis and determination of standardised ileal amino acid digestibilities from casein in newly weaned pigs

AbstractBACKGROUND: This study was carried out to estimate basal ileal endogenous crude protein (CP) and amino acid (AA) losses (IAALB) in newly weaned pigs by regression analysis from apparent ileal digestible and the corresponding total dietary contents of CP and AA in order to obtain standardised ileal digestibilities (SID) of CP and AA originating from casein. A total of fourteen 3‐week‐old barrows were fitted with simple T cannulas at the distal ileum and were fed six diets with two pigs per diet in 4 weekly repeated measurements. Corn starch‐based diets containing six graded levels of CP from casein with 90, 155, 220, 285, 350 and 415 g kg−1 CP (as‐fed basis) were formulated.RESULTS: Linear relationships (P &lt; 0.001) between apparent ileal digestible and total dietary contents of CP and AA (g kg−1 dry matter intake (DMI)) exist for CP and all AA in the range of 90–220 g kg−1 CP content in the diet. The IAALB extrapolated from the range of 90–220 g kg−1 CP content are different from zero (P &lt; 0.001 to P = 0.019) except for tryptophan (P = 0.220). Based on regression analysis in the range of 90–220 g kg−1 CP, estimates of IAALB, expressed as g kg−1 DMI, and SID of CP and AA in casein (in parentheses, %) were as follows: CP 9.3 (98.0); arginine 0.4 (98.9); histidine 0.2 (98.5); isoleucine 0.2 (98.1); leucine 0.5 (99.2); lysine 0.4 (99.0); methionine 0.1 (99.1); phenylalanine 0.4 (99.9); threonine 0.6 (97.8); tryptophan 0.1 (96.2); valine 0.4 (98.5).CONCLUSION: The IAALB and SID of CP and AA originating from casein in newly weaned pigs are in close agreement with values obtained in grower finisher pigs. Copyright © 2007 Society of Chemical Industry

Evaluating standardized ileal digestibility of amino acids in growing pigs

The ileal digestibility coefficient (CSID) of amino acids (AA) and crude protein (CP) in 40 feedstuffs for growing pigs were determined with the protein-free (PF) and enzyme-hydrolyzed casein (EHC) methods. The 40 feedstuffs that were used earlier were 10 samples of cereals and cereal by-products, 12 samples of legumes, 6 samples of animal protein feedstuff and 12 samples of oil seed meals. Six growing pigs (initial body weight of 35 ± 1.5 kg), fitted with T-cannula at the terminal ileum, were randomly allocated to either a PF or a EHC diet according to a crossover design during two ileal digesta collection periods. In each period, pigs were adjusted to the experimental diets for 5 days. On days 6 and 8, ileal digesta were collected continuously for 24 h to determine ileal endogenous AA and CP losses. Pigs fed the EHC diet had a higher ileal flow of endogenous CP and of most of AA (P<0.05) than pigs fed the PF diet. Among the ileal endogenous AA flows (g/kg dry matter intake for pigs), methionine excretion was the lowest in pigs (0.09 and 0.25 g/kg dry matter intake) fed the PF and EHC diet, respectively, whereas glutamate (1.83 g/kg dry matter intake) and proline (1.22 g/kg dry material intake) excretion were the highest in pigs fed the EHC and the PF diet, respectively. Endogenous losses of CP and AA determined in the current study and previously published data on apparent ileal digestibility [Yin, Y.L., Huang, R.L., Zhong, H.Y., Chen, C.M., Li, T.J., Pan, Y.F., 1993. Nutritive value of feedstuffs and diets for pigs: 1. Chemical composition, apparent ileal and fecal digestibilities. Anim. Feed Sci. Technol. 44, 1–27] were used to calculate CSID coefficients. For most cereals and cereal by-products, the CSID coefficients of CP determined by the EHC method were higher than those determined by the PF method. Arginine, lysine, methionine, threonine, valine, alanine, aspartate, glutamate, glycine, proline and serine in some cereals and cereal by-products; methionine, valine, alanine and proline in some legumes; and methionine, alaline and proline in some oilseed meals had higher CSID determined by the EHC method than the PF method indicating that there are methodological differences when evaluating the CSID of feed ingredients.

Effect of dietary inclusion of hazelnut and soybean meals on microbial protein synthesis

The aim of this study was to compare effects of dietary inclusion of hazelnut meal (HZM) with soybean meal (SBM) on site of digestion and microbial protein synthesis in sheep. Four ruminally and duodenally cannulated female Redkaraman × kıvırcık sheep (initial BW of 44.0 ± 1.02 kg) were utilized in a crossover experiment. Sheep were fed a diet of 60% corn silage (DM basis) and 40% concentrate consisting of barley and SBM or HZM. Feed was fed at 115% of ad libitum intake. Intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were similar between sheep fed SBM or HZM based diets ( P > 0.05). Organic matter intake averaged 1089 (2.37% BW) and 1143 g/day (2.42% BW) for SBM and HZM, respectively. Apparent and true ruminal and total tract DM and OM digestibilities did not differ between diets ( P > 0.05). True ruminal OM digestibility was 74.3 and 74.6% for SBM and HZM based diets, respectively. Total CP entering the duodenum was similar between diets ( P > 0.05). Dietary plus endogenous CP entering the duodenum in grams and as a percentage of total CP was greater ( P < 0.05) for SBM versus HZM. Quantities of microbial protein ( P < 0.15) and NH 3 N ( P < 0.08) flowing to the duodenum tended to be less for SBM versus HZM; percentages of total CP were lower ( P < 0.05) for SBM. Apparent ruminal and total tract CP digestibilities did not differ between diets, but true ruminal CP digestibility and efficiency of microbial protein synthesis tended to be higher in animals fed the HZM based diet compared with the diet based on SBM ( P < 0.13). In conclusion, because total CP entering duodenum did not differ between diets, HZM can be substituted for SBM in sheep fed corn silage and barley based diets with a moderate CP level.

Variation in precaecal amino acid and energy digestibility between pea (Pisum sativum) cultivars determined using a linear regression approach

1. 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. 2. 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. 3. 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. 4. 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. 5. 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 arginine > glutamic acid > lysine > methionine > phenylalanine > leucine. The AAs with the consistently lowest digestibilities were cystine < threonine. The ranking of the remaining AAs varied slightly between cultivars. 6. The multiple linear regression approach is suitable to study differences in AA digestibilities without the need for consideration of basal endogenous AA losses. 7. 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.

Effect of including purified jack bean lectin in casein or hydrolysed casein-based diets on apparent and true ileal amino acid digestibility in the growing pig

AbstractThe effect of including purified jack bean lectin (concanavalin A) in the diet of grower pigs on endogenous ileal nitrogen (N) and amino acid (AA) losses, and apparent and true ileal AA digestibility was investigated in a study with four growing pigs (average initial live weight (LW) 25 kg) fitted with simple T-cannulae at the terminal ileum. Both the homo-arginine (HA) method and peptide-alimentation method were used to estimate endogenous gut AA losses. The animals were offered four diets :(1) an enzymatically hydrolysed casein (EHC) containing diet, (2) an EHC containing diet supplemented with 266 mg/kg jack bean lectin, (3) a normal casein (NC) containing diet, and (4) a NC containing diet supplemented with 266 mg/kg lectin. For the estimation of ileal endogenous AA flows in pigs given NC diets, a subsample ofNC was guanidinated to convert lysine to HA. The experiment was conducted using a 4X4 Latin-square design. In each experimental period, pigs were adjusted to the experimental diets for 5 days. On day 6, ileal digesta was collected continuously for 24 hfor determination of apparent ileal digestibility. At 08:30 h of day 8 the HA NC diets were offered to pigs on NC treatments and ileal digesta were again collected for 24 h from all pigs. There were no interactive effects of casein type and added dietary lectin on apparent and true ileal AA digestibility and endogenous ileal AA flows (P &gt; 0-05). The addition of lectin to the diet did not influence (P &gt; 0-05) the apparent ileal digestibility of dry matter (DM), crude protein (CP) and AA. Casein type did not affect ileal DM digestibility (P &gt; 0-05). Pigs given the NC-based diets had higher (P &lt; 0-05) apparent ileal AA digestibility than pigs given the EHC-based diets. Addition of lectin to the diet did not influence (P &gt; 0-05) endogenous ileal CP and AA flows. Endogenous ileal AA losses were generally higher (P &lt; 0-05) in pigs given EHC diets than in pigs given NC diets. Neither casein type nor diet lectin level influenced (P &gt; 0-05) the true ileal digestibility ofCP and AA; values ranged for most AA between 0-98 and 1-00. These data suggest that including purified jack bean lectin at the level of 266 mg/kg in a casein-based diet did not influence the ileal endogenous CP and AAflow, nor the apparent and the true ileal digestibility ofCP and AA, in growing pigs between 25 and 50 kg LW. Compared with the HA method, the peptide-alimentation method yielded higher estimates of ileal endogenous CP and AA acid losses in pigs given casein-based diets, although these two methods yielded similar estimates of true ileal AA and CP digestibility.

Evaluation through literature data of the amount and amino acid composition of basal endogenous crude protein at the terminal ileum of pigs

The paper summarizes and evaluates data on estimates for the amount and amino acid (AA) composition of basal endogenous crude protein (CP) at the terminal ileum of pigs derived from 33 ileal digestibility studies with pigs (30–100 kg BW). Different methods and approaches are used to obtain these estimates: (A) the N-free diet method (16 studies), (B) calculations based on ileal digestibility values of diets with highly digestible protein sources (casein or wheat gluten) (11 studies), (C) the regression method (3 studies), (D) the enzymatic hydrolyzed casein (EHC) method (2 studies) and (E) the N-free diet method with intravenous infusion of AAs (1 study). The mean values for the flow of basal endogenous ileal CP (6.25× N) for the five respective methods were 10.5, 12.6, 12.0, 17.1 and 12.7 g/kg dry matter (DM) intake. The overall mean value using all observations was 11.8 g/kg DM intake. The mean AA composition of basal endogenous protein (g/16 g N) was estimated as 3.2 for isoleucine, 4.2 for leucine, 3.4 for lysine, 1.0 for methionine, 1.8 for cystine, 2.9 for phenylalanine, 2.6 for tyrosine, 5.1 for threonine, 1.2 for tryptophan, 4.5 for valine, 3.4 for arginine and 1.6 for histidine. The flow of basal endogenous ileal CP and AAs can be considered as an inevitable loss for the pig. Data on the flow of basal endogenous protein and AAs can be used to calculate true or standardized ileal digestibility values or corrected apparent ileal digestibility values of feed ingredients for pigs. The use of more accurate and additive ileal digestibility values of AAs in feed ingredients improves diet formulation for pigs, in which AA supply via the diet is matched with AA requirements.

Studies on the Effect of Dietary Crude Protein Supply on the Composition of Ileal Endogenous Crude Protein Loss in Growing Pigs

Two experiments were carried out to investigate endogenous crude protein (N 2 6.25) (CP) losses in growing pigs. In experiment I, 42 cross-bred gilts [live weight (LW) 35-40 kg] were fitted with a simple T-cannula at the terminal ileum. Seven experimental diets (four feedstuffs: barley, wheat, soyabean meal and rapeseed meal, and three mixtures with varying compositions of the same feedstuff batches) were investigated. Each diet was fed at six different CP levels, obtained after dilution with a 1:1 mixture of sucrose and dextrose. In total, 42 different diets were used and on each pig three different diets were tested. In experiment II, 12 (LW , 18 kg) plus eight (LW , 88 kg) cross-bred castrates were fitted with a simple T-cannula at the terminal ileum. Four experimental diets based on casein as the sole protein source and with CP dietary levels from 6 to 25% were used. By extrapolation to zero CP intake the basal endogenous protein loss in experiment I was 15.7 g kg -1 dry matter (DM) intake, when including all diets, and 14.3 g kg -1 DM intake after excluding the barley diets. In experiment II the basal endogenous CP loss was 11.3 g kg -1 DM intake. In experiment I a relative increase in almost all amino acids in the endogenous CP loss was found when the dietary CP level in the diets increased from zero to 17%. Exceptions were glycine, which was constant, and proline, which decreased significantly from 176 to 58 g 160 g -1 CP. However, the sum of proline and glutamic acid in the endogenous protein loss was almost constant. Similar results were obtained after correction for undigested dietary CP and amino acids, based on in vitro analyses of CP digestibility. In a supplementary study, ileal samples, selected for unusually high levels of proline were analysed for free amino acids. For proline, 36-64% was free, whereas insignificant proportions of the other amino acids were free. It is concluded that the composition of endogenous CP is generally relatively constant. However, experimental conditions with low or inappropriate dietary CP supply may influence the composition and occasionally induce unexpected high levels of proline from secretion of free proline into the lumen of the digestive tract.

Partitioning of Amino Acids Flowing to the Abomasum into Feed, Bacterial, Protozoal, and Endogenous Fractions

We partitioned the flow of amino acids (AA) to the abomasum among rumen undegradable protein (RUP) and bacterial, protozoal, and endogenous fractions using four Holstein cows in midlactation that were equipped with ruminal and abomasal cannulas. A 2 × 2 factorial design with four diets, combinations of high or low ruminally degradable organic matter, and rumen degradable protein, was employed. Crude protein (CP) and AA contents of ruminal bacteria and protozoa and abomasal digesta were determined. Equations for the source compositions and in vivo flows of CP and 16 AA were then solved simultaneously with a linear program to estimate the contribution of RUP, bacterial, protozoal, and endogenous CP to AA flows. The flows of RUP and bacterial AA were not affected by diet. Low dietary RDP increased the flow of protozoal AA to the abomasum, but the ruminally degradable organic matter content of the diet did not affect protozoal AA flow. Across diets, RUP, bacterial, protozoal, and endogenous fractions provided 55, 33, 11, and <1% of the CP, and 62, 26, 12, and <1% of the AA that reached the abomasum. The linear program was a useful tool for partitioning AA that flows to the abomasum. The technique may also allow dietary effects on ruminal microbes and the AA profile of protein flowing to the duodenum to be better understood and perhaps manipulated.

Protein and amino acid metabolism in the gastrointestinal tract of young bulls. 3. Flow of NH3-free raw protein into the duodenum

The amount of NH3-free crude protein getting into the duodenum corrected by the endogenous crude protein quota was determined on the basis of 28 differently composed rations for growing bulls in the live weight range of 140-460 kg provided with duodenal re-entrant cannulae. The experimental results were generalized by means of regression analysis and can be summarized as follows: The amount of NH3-free crude protein getting into the duodenum can partially be calculated with the regression equation (Formula: see text) resp. NH3-free crude protein D = 155 app. dig. org. matter + 0.262 pure protein +/- 42. The remaining dispersion amounts to +/- 6% of the mean value. The coincidence between the values calculated with these equations and those measured experimentally is very good. There is an interaction between the pure protein of feed getting into the duodenum in % of pure protein intake (y) and the bacteria crude protein D/kg app. dig. org. matter (x) characterized by the equation y = 116.8-0.52 x +/- 12.9. The amount of NH3-free crude protein duod. is not influenced by the flow rate (kg digesta/kg intake of org. matter) and not by the "dilution rate' (g bacteria free org. matter duod./kg live weight 0.75/h) either at a DM intake adequate to the production level. Apart from the partial estimation of the NH3-free crude protein duod. a evaluation based on the crude protein and pure protein concentration in app. dig. org. matter of the ration is possible.

Simultaneous diffusion and reaction of azide in a cylindrical crystal of ferrimyoglobin

The aim of this study was to compare effects of dietary inclusion of hazelnut meal (HZM) with soybean meal (SBM) on site of digestion and microbial protein synthesis in sheep. Four ruminally and duodenally cannulated female Redkaraman × kıvırcık sheep (initial BW of 44.0 ± 1.02 kg) were utilized in a crossover experiment. Sheep were fed a diet of 60% corn silage (DM basis) and 40% concentrate consisting of barley and SBM or HZM. Feed was fed at 115% of ad libitum intake. Intakes of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were similar between sheep fed SBM or HZM based diets (P > 0.05). Organic matter intake averaged 1089 (2.37% BW) and 1143 g/day (2.42% BW) for SBM and HZM, respectively. Apparent and true ruminal and total tract DM and OM digestibilities did not differ between diets (P > 0.05). True ruminal OM digestibility was 74.3 and 74.6% for SBM and HZM based diets, respectively. Total CP entering the duodenum was similar between diets (P > 0.05). Dietary plus endogenous CP entering the duodenum in grams and as a percentage of total CP was greater (P < 0.05) for SBM versus HZM. Quantities of microbial protein (P < 0.15) and NH3 N (P < 0.08) flowing to the duodenum tended to be less for SBM versus HZM; percentages of total CP were lower (P < 0.05) for SBM. Apparent ruminal and total tract CP digestibilities did not differ between diets, but true ruminal CP digestibility and efficiency of microbial protein synthesis tended to be higher in animals fed the HZM based diet compared with the diet based on SBM (P < 0.13). In conclusion, because total CP entering duodenum did not differ between diets, HZM can be substituted for SBM in sheep fed corn silage and barley based diets with a moderate CP level.