scholarly journals Protein metabolism in the rumen of silage-fed steers: effect of fishmeal supplementation

1988 ◽  
Vol 60 (2) ◽  
pp. 339-353 ◽  
Author(s):  
J. M. Dawson ◽  
C. I. Bruce ◽  
P. J. Buttery ◽  
M. Gill ◽  
D. E. Beever
Keyword(s):  
Live Weight ◽  
Period Change ◽  
Diaminopimelic Acid ◽  
Growth Responses ◽  
Microbial Protein ◽  
Total N ◽  
Mean Values ◽  
Rumen Microbes ◽  
Dietary Nitrogen ◽  
Microbial N

1. Ryegrass (Lolium perenne cv. Cropper) silage was given to four Friesian steers (initial live weight (LW) 172 kg) alone or with a fishmeal supplement (150 g fresh weight/kg silage dry matter (DM)) in a balanced two- period change-over design. The dietary components were the same as those used in a recent experiment by Gill et al. (1987). All diets were offered hourly at 24 g DM/kg LW.2. Fishmeal supplementation increased dietary nitrogen intake (P < 0.01) and significantly increased the flow of total N (P < 0.01), non-ammonia N (NAN) (P < 0.01) and amino acids (P < 0.05) at the duodenum. The increased supply of NAN to the duodenum was due largely (67%) to increased flow of undegraded dietary protein.3. Microbial protein production was estimated simultaneously with 15N, diaminopimelic acid (DAPA) and a novel technique using L-[4,5-3H]leucine. Estimates varied with the marker and source of microbial isolate but mean values indicated that microbial N flow was significantly increased by fishmeal supplementation (P < 0.05). The use of L-[4,5-3H]leucine as a microbial marker is justified and its possible advantages over other markers are discussed.4. The efficiency of microbial protein synthesis was significantly increased from 30.8 g N/kg organic matter apparently digested in the rumen (OMADR) to 54.3 gN/kg OMADR by fishmeal supplementation (P < 0.01). However, this indicates that relatively high efficiencies can be achieved with unsupplemented high quality silage supplied continuously. Rumen degradable N (RDN) supply was significantly increased by fishmeal supplementation (P < 0.05) but apparent efficiency of capture of RDN by rumen microbes was not significantly increased.5. Attempts were made to investigate the source of N utilized by the microbes on the two diets by intrarumen infusions of (15NH4)2SO4 and L-[4,5-3H]leucine but these were confounded by rumen-mixing problems. Findings obtained suggest that a lower proportion of microbial N may have been derived from rumen ammonia when the silage was supplemented with fishmeal but no differences in the extent of direct incorporation of leucine into microbial protein were observed. This could indicate an increase in microbial peptide uptake on the fishmeal-supplemented diet. However, evidence was also obtained suggesting that the improvement in microbial protein synthetic efficiency with supplementary fishmeal was also due to the provision of a more continuous supply of nitrogenous substrates for microbial growth, as a result of hourly feeding.6. The results are related to the increased growth responses attained by fishmeal supplementation of this silage in the experiment of Gill et al. (1987).

scholarly journals Microbial protein synthesis in cattle given roughage–concentrate and all-concentrate diets: the use of 2,6-diaminopimelic acid, 2-aminoethylphosphonic acid and 35S as markers

1984 ◽  
Vol 52 (2) ◽  
pp. 249-260 ◽  
Author(s):  
F. G. Whitelaw ◽  
J. Margaret Eadie ◽  
L. A. Bruce ◽  
W. J. Shand
Keyword(s):  
Microbial Population ◽  
Daily Intake ◽  
Specific Radioactivity ◽  
Live Weight ◽  
Dietary Treatment ◽  
Diaminopimelic Acid ◽  
Energetic Efficiency ◽  
Microbial Protein ◽  
Representative Sampling ◽  
Microbial N

1. Three steers, each fitted with a rumen cannula and a re-entrant cannula in the proximal duodenum, were offered diets consisting of a barley-based concentrate and chopped hay at a daily intake of 61 g/kg live weight0-75 given in three. equal meals. The ratio, concentrate: hay was changed from 50: 50 to 90: 10 and then to 100: O in successive periods of 12–18 weeks and the flow and composition of digesta at the duodenum was measured over 48-h periods on each dietary treatment.2. Samples of bacteria and protozoa were separated from rumen contents and the proportions of bacterial and protozoal nitrogen (N) in duodenal digesta were estimated using 2, ddiaminopimelic acid (DAPA) and 2- aminoethylphosphonic acid (AEP) as markers. On separate occasions, radioactive sulphur (35S) was infused into the rumen for 48 h and digesta collected over the final 24 h; the specific radioactivity of S in microbial and digesta fractions was used to estimate the proportions of microbial N.3. 35S gave reproducible and apparently reliable estimates of microbial protein formation: the proportion of microbial N in digesta was significantly higher (P < 0.05) for the 50:50 diet than for the other treatments but the energetic efficiency of microbial protein formation did not differ significantly between diets.4. Estimatesof bacterial N based on DAPA concentrations were highly variable and frequently impossibly high. It is suggested that many of the anomalous values were the result of non-representative sampling of the rumen microbial population and that this is particularly likely to occur when conditions within the rumen are unstable. AEP was found to be unsuitable as a marker for rumen protozoa as considerable concentrations of this substance were found also in rumen bacteria.

scholarly journals Digestion and synthesis in the rumen of sheep given diets supplemented with free and protected oils

1983 ◽  
Vol 49 (3) ◽  
pp. 419-432 ◽  
Author(s):  
J. D. Sutton ◽  
R. Knight ◽  
A. B. McAllan ◽  
R. H. Smith
Keyword(s):  
Protein Synthesis ◽  
Linseed Oil ◽  
Latin Square ◽  
Coconut Oil ◽  
Sodium Caseinate ◽  
Diaminopimelic Acid ◽  
Microbial Protein ◽  
Total N ◽  
Microbial Protein Synthesis ◽  
Microbial N

1. Six wether sheep were each provided with a permanent cannula in the rumen and re-entrant cannulas in the proximal duodenum.2. In a preliminary study, the sheep consumed 200 g hay and 400 g concentrates supplemented with up to 40 g linseed oil, coconut oil or cod-liver oil daily. Feed was refused at higher levels of supplementation.3. Five of the sheep were used in a 5 × 5 Latin-square experiment. They were given 200 g hay and 400 g concentrates alone (B) or supplemented with 40 g linseed oil (L), coconut oil (C), protected linseed oil or protected coconut oil daily. The protected oils were prepared by emulsifying the free oils with formaldehyde-treated sodium caseinate. Formaldehyde-treated sodium caseinate was also included in the other three diets.4. Digestion in the stomach was measured by spot sampling duodenal digesta, using chromic oxide-impregnated paper as the marker. Microbial flow at the duodenum was measured by use of both diaminopimelic acid (DAPA) and RNA as microbial markers.5. Both the free oils had broadly similar effects despite their very different fatty acid compositions. Digestion in the stomach of organic matter (OM) was reduced from 0·48 (diet B) to 0·29 (diets L and C) and that of neutral-detergent fibre from 0·50 (diet B) to 0·19 (diet L) and 0·12 (diet C). The molar proportions of acetic acid and n-butyric acid were decreased and that of propionic acid was increased. Protozoal numbers were reduced by 78% (diet L) and 90% (diet C). The flow of total nitrogen and microbial N was increased by both oils and the efficiency of microbial protein synthesis (g N/kg OM apparently digested in the rumen) was increased from 30 (diet B) to 85 (diet L) and 74 (diet C) when based on DAPA and from 41 (diet B) to 94 (diet L) and 81 (diet C) when based on RNA. The efficiency when based on true digestion of OM (g N/kg OM truly digested in the rumen) was increased from 23 (diet B) to 46 (diet L) and 44 (diet C) when based on DAPA and from 29 (diet B) to 49 (diet L) and 46 (diet C) when based on RNA. The amounts of microbial OM (g/d) at the duodenum were increased from 68 (diet B) to 124 (diet L) and 106 (diet C) when based on DAPA and from 92 (diet B) to 136 (diet L) and 115 (diet C, non-significant) when based on RNA.6. When the oils were given in the protected form, the effects on digestion in the stomach were reduced but not eliminated. No significant increases in the amount of total N or microbial N at the duodenum were established, though there was a tendency for an increase in the efficiency of microbial protein synthesis with protected linseed oil. The results suggested that the method of protection used reduced the effects of the oils on rumen digestion and synthesis but was only partially successful in preventing hydrogenation of the fatty acids.7. It is concluded that free oils can markedly increase the efficiency of microbial protein synthesis, possibly by their defaunating effect, and that this may enhance the potential for using non-protein-N on oil-supplemented diets.

Rumen microbial protein supply to sheep given diets containing either urea or casein as the main N source

1992 ◽  
Vol 1992 ◽  
pp. 215-215
Author(s):  
X. B. Chen ◽  
C. X. Gu ◽  
W. X. Zhang ◽  
E. R. Ørskov
Keyword(s):  
Live Weight ◽  
Basal Diet ◽  
Microbial Protein ◽  
Host Animal ◽  
Rumen Microbes ◽  
Feed Formulation ◽  
N Source ◽  
Ruminant Diets ◽  
Protein Supply ◽  
N Requirement

The ability of rumen microbes to synthesize protein from ammonia-N enables the use of non-protein-N as a N source in ruminant diets. The strategy for feed formulation therefore would be to meet the microbial N requirement with a cheap N source (such as urea) and to increase the proportion of dietary protein for use directly by the host animal. There has been some indication that the efficiency of rumen microbial protein synthesis could be higher if protein N is provided (Stock, Klopfenstein, Brink, Britton and Harmon, 1986). The objective of this experiment was to compare the use of urea and casein as a source of rumen degradable nitrogen (RDN) for the production of microbial protein in sheep.Five male Blackface x Suffolk lambs (33-42 kg live weight) fitted with rumen cannula were used. The animals were fed a restricted amount (721 g DM/day) of a low-N basal diet with or without supplementation with either urea or casein.

The simultaneous use of ribonucleic acid, 35S, 2,6-diaminopimelic acid and 2-aminoethylphosphonic acid as markers of microbial nitrogen entering the duodenum of sheep

1978 ◽  
Vol 39 (1) ◽  
pp. 165-179 ◽  
Author(s):  
J. R. Ling ◽  
P. J. Buttery
Keyword(s):  
Fish Meal ◽  
Barley Grain ◽  
Soya Bean ◽  
Diaminopimelic Acid ◽  
Estimation Methods ◽  
Mean Values ◽  
Advantages And Disadvantages ◽  
Bean Meal ◽  
Soya Bean Meal ◽  
Microbial N

1. Three sheep, each fitted with a ruminal cannula and duodenal re-entrant cannulas were given three isonitrogenous, isoenergetic diets in a Latin-Square design. Each diet contained (/kg) approximately 400 g N as white fish meal, soya-bean meal or urea and approximately 600 g dry matter (dm) was barley grain. The diets were fed continuously and supplied about 28 g N/d.2. Total duodenal digesta was collected manually for 72 h and the proportions of microbial N in that digesta were simultaneously estimated for all sheep using RNA, radioactive sulphur (35S), diaminopimelic acid (DAPA) and aminoethylphosphonic acid (AEPA) as markers.3. Three of the estimation methods showed that the variable source of dietary N had the greatest (RNA P < 0.05, 35S P < 0.005, DAPA P < 0.1) effect on the proportions of microbial N in duodenal digesta, though differences between sheep accounted for some variation.4. These methods also ranked the diets in the order: urea > soya-bean meal > fish meal with respect to the proportions of digesta N that were microbial in origin; the respective mean values for these diets with the different markers were: RNA 0.98, 0.70, 0.56; 35S 0.92, 0.64, 0.54; DAPA 0.80, 0.47, 0.42.5. AEPA was found to be present in substantial quantities not only in isolated rumen protozoa, but also in dietary and bacterial material; an observation that invalidated its further use as a protozoal marker.6. Calculations using values obtained from the 35S procedure showed that the proportions of dietary N degraded within the rumen were 0.38, 0.43 and 0.89 for the white fish meal, soya-bean meal and barley respectively.7. The marker methods are compared and their advantages and disadvantages (real and apparent) are discussed. It is concluded that where microbial N estimates of a more general and comparative nature are required, the use of RNA as a marker is probably adequate. Where information for more exacting purposes is required, the use of 35S appears to be more appropriate.

scholarly journals The efficiency of microbial protein synthesis in the rumen and the degradability of feed nitrogen between the mouth and abomasum in steers given different diets

1984 ◽  
Vol 51 (1) ◽  
pp. 77-83 ◽  
Author(s):  
A. B. McAllan ◽  
R. H. Smith
Keyword(s):  
Protein Synthesis ◽  
Fish Meal ◽  
Basal Diet ◽  
Metabolizable Energy ◽  
Diaminopimelic Acid ◽  
Barley Straw ◽  
Microbial Protein ◽  
Total N ◽  
Microbial Protein Synthesis ◽  
Mixed Bacteria

1. Protozoa-free steers with simple rumen and abomasal cannulas were given basal diets consisting of a concentrate mixture of flaked maize and tapioca with barley straw (BS) or alkali-treated barley straw (BSA). Other diets were supplemented with urea (BSU and BSAU respectively) or with fish meal replacing the tapioca (BSF and BSAF respectively). The diets were isoenergetic and calculated to provide sufficient metabolizable energy (ME) to support a growth rate of 0.5 kg/d. Rumen-degradable nitrogen (RDN): ME values (g/MJ) were estimated to be 0.50, 1.20 and 0.80 for the basal diet, urea- and fish-meal-supplemented diets respectively. RNA and α, ε-diaminopimelic acid (DAP) were used as microbial markers. 103Ruthenium and polyethylene glycol (PEG) were given as flow markers and flows (g/24 h) at the abomasum of organic matter (OM) and nitrogenous constituents were calculated.2. Samples of mixed bacteria separated from rumen digesta from animals receiving N-supplemented diets contained significantly more N than those from animals receiving basal diets (approximately 74 and 62 mg/g dry matter (DM) respectively) but there were no other significant differences in total-N contents between treatments. RNA-N: total-N values were similar for all diets (approximately 0.13). DAP-N: total-N values were significantly lower in bacteria from animals receiving alkali-treated (AT) rather than untreated (UT) straw (approximately 0.008 and 0.011 respectively).3. The proportion of OM intake digested in the rumen (ADOM) was significantly higher for animals receiving AT straw rather than UT straw (approximately 0.54 and 0.43 respectively). N supplementation had no effect on OM digestibility.4. When basal rather than N-supplemented diets or AT-straw- rather than UT-straw-containing diets were given, there were significantly lower flows of ammonia-N, non-ammonia-N (NAN) and microbial-N (based on RNA flow, MN(RNA)) at the abomasum. Mean daily MN(RNA) flows (g) were 21, 30, 31, 16, 27 and 28 for diets BS, BSU, BSF, BSA, BSAU and BSAF respectively. These correspond to estimated efficiencies of microbial protein synthesis, expressed as g MN(RNA) /kg truly-digested OM, at 14, 22, 22, 12, 18 and 19 respectively. Values were significantly lower for basal as compared with corresponding N-supplemented diets and for AT-straw diets as compared with corresponding UT-straw diets.5. Estimated mean proportions of total feed-N intake degraded in the rumen, based on MN(RNA) as microbial marker, of diets BS, BSU and BSF were 0.60, 0.74 and 0.47 respectively; corresponding values for diets BSA, BSAU and BSAF were 0.72, 0.73 and 0.36 respectively. Making certain assumptions, the mean proportions of fish-meal-N digested in the rumen were calculated to be 0.23 and 0.14 respectively for UT- and AT-straw diets. The values were not significantly different. Values for microbial flows based on DAP as marker were significantly lower, by about 25%, than those based on RNA.

scholarly journals The simultaneous estimation of the amounts of protozoal, bacterial and dietary nitrogen entering the duodenum of steers

1984 ◽  
Vol 51 (1) ◽  
pp. 111-132 ◽  
Author(s):  
J. E. Cockburn ◽  
A. P. Williams
Keyword(s):  
Latin Square ◽  
Diaminopimelic Acid ◽  
Simultaneous Estimation ◽  
Rumen Bacteria ◽  
Bacterial Protein ◽  
Flow Estimation ◽  
Dietary Nitrogen ◽  
Amino Acid Profiling ◽  
Dietary Casein ◽  
Microbial N

1. Four steers were given straw and tapioca diets, twice daily, in a 4 x 4 Latin-square design. These diets, containing 4.2 g nitrogen/kg dry matter (DM), were further supplemented with either urea, decorticated groundnut meal (DCGM), untreated (UT) casein or formaldehyde-treated (FT) casein to give a total of 19.7 g N/kg DM and 10.5 MJ/kg DM daily.2. Concurrent samples of rumen bacteria and protozoa and abomasal digesta were collected for each period of the experiment and the concentrations of 2-aminoethyl phosphonic acid (AEPA), diaminopimelic acid (DAPA), total nitrogen (TN), total phosphorus (TP), amino acids and hexosamines were determined in the dried preparations. The nature of the dietary supplements had little effect on the concentrations of most of these constituents or on the total protozoal numbers.3. Abomasal digesta samples marked with polyethylene glycol (PEG) and chromic oxide for flow estimation were collected over 24 h, and the proportions of protozoal-N, bacterial-N and microbial-N estimated simultaneously using the markers AEPA, DAPA and RNA respectively. These digesta-N components were also estimated using an amino acid profiling (AAP) method which gave, in addition, estimates of the dietary and endogenous components. For the diets containing casein, the proportion of dietary casein was estimated directly using casein-P as a marker.4. Estimates of the respective mean proportions of microbial-N in abomasal digesta non-ammonia-N (NAN) for the diets containing urea, DCGM, UT casein or FT casein were: AEPA 0.56, 0.32, 0.27 and 0.16; DAPA 0.88, 0.70, 0.81 and 0.57; RNA 0.98, 0.85, 0.92 and 0.53.5. Giving FT casein significantly (P< 0.001) increased the flow of casein-N at the abomasum and a significantly (P< 0.001) greater proportion of casein-N was found in abomasal NAN (0.51v.0.09) where FT rather than UT casein was given.6. The AAP method gave results for the proportions of microbial- and dietary-N (where casein was given) which were, in general, slightly lower than those obtained using RNA and casein-P as markers. Agreement with estimates of bacterial protein (from DAPA) and of protozoal protein (from AEPA) was less satisfactory.7. Comparisons of the various estimates of the proportions of microbial-N in abomasal digesta suggested that the results obtained for protozoal-N by AEPA were overestimates. AEPA was found in mixed rumen bacteria which may have accounted in part for these overestimates. However, AEPA was not detected in any of the dietary ingredients.

Contribution of dietary nitrogen and purine bases to the duodenal digesta: comparison of duodenal and polyester-bag measurements

1997 ◽  
Vol 65 (2) ◽  
pp. 237-245 ◽  
Author(s):  
J. F. Pérez ◽  
J. Balcells ◽  
J. A. Guada ◽  
C. Castrillo
Keyword(s):  
Live Weight ◽  
Dietary Treatment ◽  
Mean Value ◽  
Barley Grain ◽  
Barley Straw ◽  
Total N ◽  
Dietary Nitrogen ◽  
Direct Measurements ◽  
Bean Meal ◽  
Soya Bean Meal

AbstractFour ewes fitted with ruminal and duodenalT-piece cannulas were given fourdietsin a 4 × 4 factorial design. Diets consisted of 700 (HF) or 400 (LF) g/day of ammonia-treated barley straw supplemented respectively with 150 or 600 g/day of concentrate made up with barley plus either soya-bean meal (SBM) or fishmeal (FM) as the protein source, offered at 2-h intervals. Duodenal flowsof digestawere estimated by the dual-phasetechniqueusing CoEDTAand Yb-acetate as markers and (15NH4)2SO4 was infusedinto the rumento label microbial N. Bacteria were isolated from the liquid (LAB) or solid (SAB) rumendigesta. Purinebases (PB) were isolated by precipitationin an acid solution of AgN03, and microbial contribution either to the duodenalnitrogen(N) or PB were determinedby 15N measurements induodenaldigesta and bacteria.Simultaneously, therumen degradation of Nand PB contained in SBM and FM was studiedby incubating supplements in polyesterbags in the rumen.PBcontent (mmol/g dry matter)and guanine: adenine(G/A) ratio of barley strawwas 2·89 and 5·23; barley grain,7·91 and 111;SBM, 18·8 and 1·26; and FM, 58·9 and 6·96, respectively. Duodenal flow ofPB(mmol/day)was significantly higher than PB intake on all diets and G/A ratio showed a meanvalue of 0·97, similarto the ratios determined in SAB(0·80) and LAB (1·04) and muchlower than diets(1·31 to 4·32). Microbial contribution to duodenal Nflow ranged from43·3% to 61·0%, beinghigherin SBM(59·0%)thanin FM(46·7%)diets. However, microbial contribution to duodenal PB was not affected by the experimentaltreatment, accounting for proportionately 0·77 of total PB at the duodenum. Rumen degradability of PB was much higher than that of total N and in both cases degradability was higher in SBM than FM. Direct measurements of non-microbialN were significantly higher than values determined by the polyester-bagmeasurements. However, once corrected forthe endogenousN (52 mgN per kg live weight)contribution, results show edan acceptable agreement. Duodenal flow of PB non-attributable to microbes (unlabelled PB) showed a mean value of 3·25 mmol/daywithouta significanteffect of dietary treatment. However, undegradablePBsupply determinedfor0·02, 0·05 and 0·08 per h fractional out flow rates were proportionately lower than 0·025 with SBM and 0·100 with FM diets of the estimated duodenalPB flow. Despite the magnitudeof the unlabelledduodenalPB, the close agreement between G/A ratios in duodenaldigesta and bacteria suggests thatthe contribution of dietary PB to the duodenalflow was low and seemsto confirm the reliability of values obtained from polyester-bag measurements.

Estimation of amounts of microbial and dietary nitrogen compounds entering the duodenum of cattle

1978 ◽  
Vol 90 (3) ◽  
pp. 557-568 ◽  
Author(s):  
R. H. Smith ◽  
A. B. McAllan ◽  
D. Hewitt ◽  
Patricia E. Lewis
Keyword(s):  
Specific Activity ◽  
Soya Bean ◽  
Diaminopimelic Acid ◽  
Inorganic P ◽  
Dietary Nitrogen ◽  
Daily Sampling ◽  
Bean Meal ◽  
Soya Bean Meal ◽  
Made In ◽  
Microbial N

SummaryYoung steers with rumen and simple duodenal cannulas were given diets of approximately equal amounts of flaked maize and hay (A) or of flaked maize and straw supplemented with decorticated groundnut meal (DCGM) (B), fishmeal (C), heated soya-bean meal (D) or raw soya-bean meal (E) or of dried grass (F). A cow with rumen and re-entrant duodenal cannulas was given diets of hay and dairy cubes.Some steers received doses of32P-labelled inorganic phosphate twice daily with their concentrate feed. This led to small diurnal variations in inorganic P–32P specific activity but at similar daily sampling times the32P specific activity in rumen bacterial nucleic acids reached a steady state after dosing for about 4 days. Contributions of microbial-N to non-ammonia-N (NA-N) entering the duodenum were then estimated by comparing nucleic acid32P/NA-N ratios in related samples of rumen bacteria and duodenal contents. Similar estimates were made in these and other animals using α-, ε-diaminopimelic acid (DAP) and ribonucleic acid (RNA) as bacterial markers.Estimates for steers given diets A, B, C and F based upon ‘32P-labelled RNA nucleotides’ were, on average, 85% of those based upon total RNA. The differences were attributed mainly to the latter being elevated by the presence of small amounts of dietary RNA. When RNA-based estimates of the proportion of microbial-N in NA-N in duodenal contents for these and other steers which were nearly free of protozoa were multiplied by 0·85 (‘adjusted RNA’) the values were, on average, similar to those based upon DAP. Similar estimates for the cow based upon ‘adjusted RNA’ measurements were, however, about twice those based upon DAP, probably because the cow contained a high protozoal population and the DAP based, method did not account for protozoal N.For some steers total flows at the duodenum of organic matter (OM), microbial-N (mean based upon ‘adjusted RNA’ and DAP) and residual food N were estimated by reference to chromic oxide. Average values for g microbial-N synthesized/kg OM truly digested in the rumen for the different diets ranged from 15 to 22 (mean 20). Mean degradabilities of food N (residual food N at duodenum/N intake) were 0·57, 0·71, 0·71, 0·70 and 0·84 for diets A, B, C, D and E respectively. No differences between diets were significant atP< 0·05.

scholarly journals Synthesis of microbial protein from ammonia in the sheep's rumen and the proportion of dietary nitrogen converted into microbial nitrogen

1970 ◽  
Vol 24 (2) ◽  
pp. 589-598 ◽  
Author(s):  
A. F. Pilgrim ◽  
F. V. Gray ◽  
R. A. Weller ◽  
C. B. Belling
Keyword(s):  
Steady States ◽  
Total Production ◽  
Microbial Protein ◽  
Entry And Exit ◽  
Nitrogenous Compounds ◽  
Dietary Nitrogen ◽  
N Concentration ◽  
Microbial Nitrogen ◽  
Starting Point ◽  
Microbial N

1. The extent to which ammonia-N (NH3-N) serves as a starting point for synthesis of microbial nitrogenous compounds was assessed when 15N as (15NH4)2SO4 was continuously infused into the rumen of a sheep for periods of 78–98 h. Steady states were reached in the composition of the rumen contents because the animal was fed equal parts of its ration at hourly intervals. Concentrations of 15N in bacterial-N, protozoal-N and rumen NH3-N were compared.2. In two trials with a low-N diet consisting largely of wheaten hay the 15N concentration in bacterial N was 76 and 78% of that in the NH3-N. For protozoa the values were more variable —64 and 43%.In two trials with a higher-N diet (lucerne hay), the corresponding values were lower—bacterial-N 62 and 64%, protozoal-N 41 and 35%.It was concluded that synthesis of microbial protein was more dependent on ammonia as a starting point with the low-N diet than with the higher-N diet.3. Entry and exit rates for ammonia into and out of the rumen system were determined, and the results, in combination with those obtained for bacterial-N in the first part of the work, allowed calculations to be made of the production of microbial-N/d formed from NH3-N, and this in turn allowed calculation of minimal values for conversion of plant-N to microbial-N in the lumen. Minimal extent of conversion was 68% for the low-N diet and 53–55% for the higher-N diet.4. Total production of microbial-N in relation to the amount of N given was also calculated by using previously reported values for the relative proportions of protozoal-N and bacterial-N in sheep given diets similar to those used here. These values for extent of conversion were 73% for the low-N diet and 58–59% for the higher-N diet.

Supplementation of maize stover for Ethiopian Menz sheep: effects of cottonseed, noug (Guizotia abyssinica) or sunflower cake with or without maize on the intake, growth, apparent digestibility, nitrogen balance and excretion of purine derivatives

1993 ◽  
Vol 57 (03) ◽  
pp. 429-436 ◽  
Author(s):  
P. O. Osuji ◽  
S. Sibanda ◽  
I. V. Nsahlai
Keyword(s):  
Live Weight ◽  
Cottonseed Cake ◽  
Guizotia Abyssinica ◽  
Microbial Protein ◽  
Purine Derivatives ◽  
Maize Stover ◽  
N Retention ◽  
Maize Grain ◽  
Sunflower Cake ◽  
Microbial N

AbstractThirty-six male Ethiopian Menz sheep (9 to 22 months old, average live weight 15·8 (s.d. 1·84) kg), given maize stover (1·5 timesad libitum) supplemented with either 75 g cottonseed cake (CSC), 114 g noug cake (NGC;Guizotia abyssinica) or 112 g sunflower cake (SFC) with or without maize grain, were used in an 88-day study comprising growth and balance trials. The trials were undertaken according to a randomized-block design with a 2 × 3 factorial arrangement.There were no significant interactions (P&gt; 0·05). Sheep consumed significantly more stover when supplemented with CSC compared with NGC and SFC (P&lt; 0·05). Maize grain significantly increased organic matter intake (P&lt; 0·001). Although CSC tended to support lower live-weight gains, the effect of protein was not significant. Maize grain increased live-weight gains (P&lt; 0·01).Urinary nitrogen (N) excretions were similar between CSC and SFC but about 0·22 higher with NGC (P&gt; 0·05). The faecal N output was 0·33 (P&lt; 0·01) and 0·18 (P&lt; 0·05) higher with CSC than with NGC and SFC respectively. Maize grain had no effect on any of the N-balance measurements.Cottonseed cake supported lower daily production of purine derivatives (PD) (P&lt; 0·01), microbial purine (P &lt; 0·01) and microbial protein (P&lt; 0·01) than either NGC or SFC. Maize grain increased the daily excretion of total PD (P&lt; 0·05), microbial purine (P&lt; 0·05) and microbial protein (P&lt; 0·05). Neither the protein source nor maize grain affected the efficiency of microbial protein synthesis. It was concluded that SFC was utilized more effectively both in terms of rumen microbial N synthesis, N retention and growth. The addition of a small amount of energy as crushed maize grain increased microbial N synthesis, N retention and live-weight gain.

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