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.     

Protein and amino acid metabolism in the digestive tract of growing young bulls. 2. Feed protein flow into the duodenum determined with 2,6-diaminopimelic acid as a marker for crude bacterial protein

The experimental ascertainment of the pure feed protein flowing into the duodenum on the basis of the calculation of the difference between the NH3-free crude protein flowing into the duodenum and the bacterial crude protein determined by means of DAPA showed the following results after the testing of 28 different rations at a dry matter intake adequate to the production level: With a variation of the pure protein in the crude protein content of the ration between 40 and 90%, the quota of feed protein flowing into the duodenum is 52.5%, and with a variation of the pure protein in the crude protein content between 80 and 90% it is 40.6%. The quota of feed protein flowing into the duodenum shows a negative correlation to the apparent digestibility of the organic matter (y=231.7 -2.52x +/- 14.5). With a DM-intake adequate to the production level the quota of feed protein flowing into the duodenum is neither influenced by the flow rate (kg digesta/kg DM-intake) nor by the 'dilution rate' (g bacteria-free DMD/kg live weight 0.75/h).     

Studies on the evaluation of feed protein for ruminants. 1. Passage of nitrogen fractions to the duodenum of dairy cows fed different protein and carbohydrate sources

The duodenal passages of non-ammonia nitrogen (NAN), amino acid N (AA-N) and microbial N (MN) were measured in seven duodenal fistulated dairy cows (6130 kg FCM/305 d) during lactation receiving 30 different rations similar to those used in dairy practice. The rations consisted of roughage (protein-rich silages, hay) and concentrate mixture (corn, barley, oat) in a ratio of 60:40 on a DM basis or roughage/concentrate mixture/fodder beets in the proportions 60:20:20 or 60:0:40 respectively. N supplements consisted of soya bean meal and peas meal (untreated or treated with formaldehyde in each case), rapeseed meal, fish meal and urea. DM intake varied between 9.6 and 19.1 kg/d, the crude fibre content between 166 and 270 g/kg DM, the crude protein (CP) content between 111 and 184 g/kg DM, the AA content (N basis) of the CP between 51 and 82%, the unfermentable CP content of the CP between 23 and 49% and the organic matter digestibility between 70 and 79%. The duodenal passage of NAN was 24.2 +/- 2.7 g/kg DM intake, 34.9 +/- 4.1 g/kg apparently digestible organic matter (in total tract, DOM), 43.3 +/- 5.5 g/kg apparently digestible carbohydrates or 4.2 +/- 0.5 g/MJ net energy fat, (y +/- s, n = 90). The value measured for AA-N was 16.8 +/- 2.9 g/kg DM intake, and that for RNA-labelled microbial CP was 146 +/- 26 g/kg DOM. NAN passage (g/kg DM intake) correlated more closely with the duodenal digesta flow rate (DFR) (kg digesta/kg DM intake) as an intrinsic animal factor (r = 0.78) and with the rumen content dilution rate (RDR) (passage of microbial-free organic matter at duodenum/kg BW0.75.h) as a ration dependent factor (r = 0.64) than with the UDP fraction (% of ration CP) (r = 0.50) or other ration parameters. It was concluded that the specific effect of protein concentrates in mixed rations on duodenal NAN yields in lactating dairy cows is lower than hitherto assumed. The duodenal NAN yield of a single feedstuff or ration (g/kg DM) in cows is dependent on animal and feeding factors. The DFR could represents a suitable target for breeding activities.     

Protein and amino acid metabolism in the digestive tract of growing bull calves. 5. The amino acid flow into the duodenum

The flow of the individual amino acids (AA) into the duodenum was determined after the feeding of 28 different rations to young bulls supplied with duodenal re-entrant cannulae in the live weight range between 140 and 460 kg. The distribution of AA into AA of bacterial origin and AA from the feed was made by difference calculation between the AA at the duodenum (corrected by the endogenous AA quota) and the AA from the bacteria crude protein, with our own results based on a constant AA composition of the bacteria crude protein; by the regression analysis from relative values according to AAD/app. dig. org. m. = a + b AAF/app. dig. org. m. and by the regression analysis of the absolute values according to AAD = b1 app. dig. org. m. + b2 AAF showed the same results from the regression methods but deviating ones from the difference method. The calculation of the flow of the individual AA into the duodenum from the AA content of the ration and the content of app. dig. org. m. of the ration is possible. The equations derived for this purpose of the individual AA are given.     

Protein and amino acid metabolism in the intestinal tract of growing young bulls. 7. Protein estimation and evaluation of protein supply in growing ruminants by the apparently digestible total protein in the duodenum based on rations

The following values were derived from experimental studies of the crude protein (CP) and amino acid (AA) metabolism of growing fattening bulls, the detailed results of which were described in installments 1-6, for the ascertainment of the content of apparently digestible total protein at the duodenum (ADTPD): a) partial method: Degradation quotaCP = NPN + 0.69 X g pure protein/CP; g AD feed PD = g CP (1 -decomposition quotaCP) X 0.72 or g AD feed PD = 0.31 X g pure protein X 0.72; g ADBPDE = 0.149 X g AD org. matter X 0.80 X 0.72 (ADBPDE = apparently digestible pure bacteria protein at the duodenum, dependent on energy release in the reticulo-rumen; g ADBPDN = g CP X (degradation quotaCP) X 0.80 X 0.72 (ADBPDN = apparently digestible pure bacteria protein at the duodenum, dependent on CP supply of rumen microbes); g AD total PD = g AD feed PD + ADBPDE g AD total PD = g AD feed PD + ADBPDN; b) summarizing method: AD total PD = 0.429 + 10.9 X 0.80/CP in % AD org. matter X (CP intake) X 0.72; AD total PD = 0.196 + 16.6 X 0.80/pure protein % AD org. m. X pure pr. intake X 0.72. The requirement of AD total PD was calculated under consideration of the endogenous urine N, skin N and hair N losses as well as protein retention per kg live weight assuming a utilization of 0.70 for this partial performance. The practical application of this balance method is demonstrated in comparison to the digestible CP-system.     

The effect of sugar beets in the ration on metabolism in the forestomach of 11 to 20-week-old calves

The influence of the replacement of cereals by sugar beet in the rations was tested with 6 calves supplied with re-entrant duodenal or ruminal cannulae in 4 measuring periods between their 11th and 17th weeks of life. The control ration (A) consisted of 60% mixed feed, 20% hay and 20% wilted silage, the test ration (B) consisted of 30% mixed feed, 33% sugar beet, 20% hay and 17% wilted silage. A contained 15% crude protein, 32% starch and 2% sugar, B in the same sequence 14, 12 and 24% (amounts in % of DM). The following results were achieved: The functional development of the rumen is largely completed three weeks after weaning. There were no qualitative changes between the 11th and 17th weeks of life. The fermentation of organic matter in the rumen (50...52%) and bacterial protein yield (2.4...2.6 g N per 100 g digestible organic matter) corresponded to that of adult ruminants. The partial replacement of cereals by sugar beet resulted in a significant increase of the molar butyric acid quota to 20.8% (B) in comparison to 13% (A) with the same level of total volatile fatty acids in the rumen, the decrease of the quota of acetic acid to 61.4% (B) in contrast to 73.5% (A) and the reduction of the ruminal NH3 concentration after feeding. The feeding of sugar beets had a positive influence on the passage of starch in the duodenum. The DM-degradation of straw in polyamide bags was also positively influenced. 62.6% (A) and 73.9% (B) of the feed N were degraded in the forestomachs. Per kg DM intake 29.8 g (A) and 28.0 g (B) non-ammonia-N (NAN) were detected at the duodenum. 54% (A) and 64% (B) of NAN consisted of bacteria N. In contrast to adult ruminants at nutrition level 1 (maintenance) a considerable net influx of endogenous N into the rumen was to be observed at a crude protein concentration in the feed of 14 to 15% (in the DM) in both groups. Accordingly, the minimum protein content of the ration (in the DM) should be above 15% in the rearing range studied.     

Urea utilization of growing lambs. 2. Growth experiments

In two growth experiments with 30 lambs per group the influence of urea (1-2% of the ration) and straw (20-30% of the ration) on the performance was studied under conditions of intensive fattening. The content of native crude protein in the rations varied between 10.1 and 18.4% of the DM. In experiment 1 the lambs of the two groups which received mixed feed for fattening lambs without urea on average consumed with 1.02 and 1.11 kg DM resp., 696 and 757 EFUcattle resp. and 173 and 189 g crude protein resp. per animal and day. The groups with wheat or barley and urea consumed 1.06 and 0.96 kg DM resp., 714 and 627 EFUcattle resp. and 209 and 155 g crude protein resp. Their weight gain of 247 g/animal and day was 24% and that of 230 g resp. 26% higher than that in the control groups without urea. The lowest dry matter intake (0.91 and 0.82 kg resp.) was shown by the animals of the groups which received wheat or barley without urea. In the second experiment the control group achieved an average daily weight gain of 327 g at an expenditure of 2.24 kEFUcattle/kg weight gain. Despite a partly higher dry matter intake, the daily EFUcattle intake was between 12.2 and 24.5% lower in the straw groups and energy expenditure increased between 12.0 and 27.8%. Urea supplements of between 1 and 2% improved dry matter, EFUcattle and crude protein intake and thus weight gain.     

Nutrient digestibility and prediction of metabolizable energy in total mixed rations for ruminants.

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%).     

Beet-vinasse (condensed molasses solubles) as an ingredient in diets for cattle and pigs - nutritive value and limitations

Sugar beet vinasse, originating as the condensed molasses residue from yeast production, was fed to bulls and pigs to determine the feed value. It contained, per kg dry matter (DM content 66.8%), 293 g crude protein, 305 g N-free extract (therefrom 34.4 g total sugar), and 395 g crude ash. The experiment was carried out with three fattening bulls (German Holstein) and four adult pigs (Gottingen Minipig). In bulls, two balance trials lasting 20 days each (10 days adaptation; 10 days collection) were conducted in which subsequently a basal ration without and with vinasse (14% in DM) was fed. In pigs, the experiment consisted of three 12-day balance trials with the final 5 days as collection period. In the first trial, pigs received a basal diet without vinasse and in the following, a mixed diet with 16 and 43% vinasse (in DM) respectively. Digestibilities of components in vinasse in bulls were: organic matter 73.5%, crude protein 72.6%, and N-free extract 52.3%. In bulls, no influence on faeces quality could be detected while feeding 14% vinasse in DM. While feeding 16% vinasse in DM to pigs, the digestibility of organic matter amounted to 72.3% (crude protein 71.8%; NfE 74.6%). Feeding higher amounts of vinasse (43% in DM) in the diet of pigs, digestibilities were reduced (organic matter: 61.6%), which might be a result of a reduced retention time of the chyme as a result of an osmotically driven diarrhoea because of unexpectedly high sulphate (136 g/kg DM) content in the vinasse. It is concluded that because of organic matter digestibility >70% for cattle and pigs, the use of vinasse in these species in small proportions is reasonable.     

Measuring of the energy turnover in adult swine during feeding of rations with potato starch, potatoes, beets, pressed shreds and coarse fodder as supplements to a basic ration. 2. Evaluation and discussion of the results for further development of energetic feed rating for swine

Energy metabolism measurings of male castrates of a live weight between 90 and 180 kg after feeding rations with a wide variety in the content of various carbohydrates (crude fibre 36-185, water soluble carbohydrates 25-306, starch 272-683 g/kg DM) formed the experimental basis of the considerations. Energy retention depended significantly on the digestibility and metabolizability of the energy, on energy concentration and the crude fibre content of the rations. By means of multiple regression analyses the energetic effect of 1 g digested matter of the carbohydrate fraction was assessed as follows: 12.9 kJ for starch, 12.1 kJ for disaccharides, 11.5 kJ for the remaining water soluble carbohydrates and 10.4 kJ for bacterially fermentable carbohydrates (BFC). There was a difference between the energetic effective value of starch and BFC. This corresponds completely to the difference in the utilization of metabolizable energy between exclusively precaecal and postileal digestion. The following conclusions are drawn for the further development of the energetic feed evaluation for pigs in the framework of the GDR feed evaluation system: --There are to be differentiated fixed values for the retention of digestible carbohydrates for the fractions starch, water soluble carbohydrates (pectin) and bacterially fermentable carbohydrates. --The influence of the digestibility of the energy in the ration on the energetic retention effect of BFC is small. The integration of these variables into an estimation equation for the energetic feed value is therefore not necessary.     

Adaptation to the digestion of nutrients of a starch diet or a non-starch polysaccharide diet in group-housed pregnant sows

A trial was conducted with twenty group-housed pregnant sows to study the adaptation in nutrient digestibility to a starch-rich diet or a diet with a high level of fermentable non-starch polysaccharides (NSP) during a time period of 6 weeks. The starch-rich diet was primarily composed of wheat, peas and tapioca, whereas soya bean hulls and sugar beet pulp, which both are highly fermentable NSP sources, were used to formulate the NSP-rich diet. The starch-rich diet and the NSP-rich diet were formulated to contain different levels of starch (298 vs. 78 g/kg) and fermentable NSP (100 vs. 300 g/kg), but a similar level of net energy (NE) (8.36 MJ/kg). The trial consisted of a 1-week adaptation period followed by a 5-week collection period. Weekly apparent faecal digestibilities of dry matter (DM), crude protein (CP), crude fat, ash and NSP were measured by using the acid-insoluble ash marker method. Apparent faecal digestibilities of DM and organic matter (OM) of both diets were similar. Faecal digestibility of CP and crude fat was lower (p < 0.001) whereas that of NSP was higher (p < 0.001) for sows that received the NSP-rich diet. Calculated NE values of both diets were similar. Sows fed the NSP-rich diet produced faeces that contained a lower (p < 0.001) DM content compared with sows that were fed with the starch-rich diet. The quantity of dry faeces was the same on both diets, therefore total faeces production (as-is basis) was higher (p < 0.01) for the sows fed the NSP-rich diet. During the 5-week collection period, no changes were observed in the digestibility of DM, OM and NSP in the NE value of the diets. Digestibilities of CP and fat, however, were lower in week 1 (p < 0.05) compared with weeks 2-5 for both diets. The DM content of the faeces and the quantity of dry faeces did not change from weeks 1-5. Diet by time interaction was not observed for any of the response variables indicating that sows adapt as quickly to a diet with a high level of fermentable NSP as to a starch-rich diet. The present trial shows that, with regard to digestibility of nutrients, pregnant sows completely adapt to a NSP-rich diet (i.e., NSP from sugar beet pulp) in 2 weeks and that the time period necessary to adapt to a starch-rich diet or a diet with a high level of fermentable NSP is similar.     

The energy requirement of heifers. 4. Comparison of the digestibility and rumen physiologic parameters in heifers and full-grown sheep

In 159 comparative studies with fully grown sheep and heifers of the digestibility and of rumen physiologic values at a variation of the feed ration in the crude fibre content between 112 and 318 g, in the crude protein content between 94 and 194 g and in the content of nitrogen free extractive between 484 and 641 g/kg DM is provided that the digestibility of energy in heifers was, on average, 4 digestibility units lower than in sheep. The corresponding values for the digestibility of crude protein and crude fibre are 12 and 3.5 digestibility units. Due to the lower methane energy excretion of the heifers the difference at the level of metabolizable energy is reduced to 1.5% of the gross energy. The level of the differences in digestibility is influenced by the development of the young cattle and the composition of the rations. In young cattle of the live weight range between 100 and 150 kg the digestibility of the energy is 6-8 units lower than in sheep. A higher crude fibre content in the ration diminishes the difference in the digestibility of energy and the nutrients between the two animal species.     

The effect of different centrifugation conditions for the isolation of mixed rumen bacteria, on their nitrogen and diaminopimelic acid content

Three cows were given two rations, a silage diet (3 animals) and a green forage diet (2 animals). Samples of rumen content were collected and aliquots of these were separated in a fraction of feed particles and protozoa (FP-fraction) and a fraction of mixed bacteria, varying the conditions of differential centrifugation. The low speed centrifugation was practised at 100 X g/5 min, 400 X g/10 min, 1000 X g/10 min, and 2000 X g/10 min. High speed conditions were 30,000 X g/30 min 4 degrees C. The lyophylisated sediments were used for determination of N and DAP. The content of N gave similar results for all fractions of mixed bacteria, the mean value being 7.43 +/- 0.48% (n = 20), while the N-content of the FP-fractions being 5.68 +/- 0.37% (n = 19). The N:DAP-ratio gave similar values for the cows fed the silage diet, the values were 29.45 +/- 1.56 (n = 12). The values for the cows receiving the green forage diet differed, the mean values were 23.08 +/- 0.88 and 42.01 +/- 5.81 (n = 5), respectively. In all five experiments highest ratios were found at 100 X g. Further investigations showed that storage at -20 degrees C rumen fluid after isolation of feed particles and protozoa decreased both the N- and DAP- content without affecting the N:DAP-ratio. Centrifugation at low speed with 100 X g resulted in a markedly decreased contamination with DAP in all the FP-fractions. Optimal conditions for separation of feed particles and protozoa from rumen fluid to get a fraction best reflecting the rumen bacterial populations are 100 X g/5 min.     

The effect of energy concentration and source on the use of feed protein and NPN in lambs. 3. Allantoin excretion and microbial protein synthesis

In an N balance experiment with male crossbreeding lambs at an age of 3 ... 4 months four different rations were given differing in energy concentration (high greater than 700 EFU cattle/kg DM and low less than 650 EFU cattle/kg DM) and in the energy source (sugar, starch or crude fibre) with crude protein intake being almost equal. The rations contained 2% urea. Microbial protein synthesis in the rumen was assessed according to ROTH and KIRCHGESSNER (1978) (1), RYS et al. (1975) (2) and BICKEL-BAUMANN and LANDIS (1986) (3) on the basis of allantoin excretion in urine. The highest ruminal protein synthesis quotas were 868 ... 921 mg protein N per kg LW0.75 in (2). In (3) 723 ... 766 mg protein N/kg LW0.75 were synthesized. From the 15N labelling of the supplemented urea and the excreted allantoin it could be calculated that 26 ... 40% of the microbial protein resulted from the urea-N of the ration. Despite a high crude protein content of the ration of between 16 and 17% in the DM and a relation of NPN: pure protein of 0.95 the utilization of the NPN in the ration was relatively high but slightly lower than the utilization of pure protein. The variants with higher energy concentration showed as a tendency higher allantoin excretion in spite of slightly lower dry matter intake and a slightly higher NPN utilization than the variants with lower energy concentration.     

Nutritive value of unconventional fibrous ingredients fed to Guinea pigs in the Democratic Republic of Congo

The energy and protein value for Guinea pigs (GP) of 9 forages (7 dicots and 2 grasses) and 5 hay-based diets was determined. The apparent faecal digestibility of dry matter, organic matter, crude protein and energy was measured on GP housed in metabolic cages. The forages and the diets were digested in vitro using pepsin and pancreatin hydrolysis and gas fermentation test to simulate stomach, small intestine and large intestine, respectively. Most of the dicots had high digestible crude protein content (152–201 g/kg DM) and the 2 grasses showed lower values (80–85 g/kg DM). Digestible energy content of the forages ranged between 5.79 to 13.08 MJ/kg DM. None of the forage species or hay-based diets provided sufficient energy to supply the 11.7 MJ/kg metabolic energy requirements. The influence of intestinal fermentation on energy and protein values was highlighted by correlations (P<0.05) between in vivo and in vitro data, including gas fermentation. It is the first time that such relationships are reported in single-stomach animals.     

The energy metabolism of growing swine in the liveweight range of 10-50 kg. I. Study design, feed intake and digestibility

Studies of the energy metabolism at maintenance and growth levels after the feeding of rations with a crude protein content of 17-24% and 44-47% resp. were carried out with hybrid pigs of line 150 in the live weight range between 10 and approximately 50 kg. This paper gives information on the methods and the outlay of the experiment and presents results concerning feed intake, live weight development and digestibility. Feed intake increased on average with growing live weight by 30-35 g DM/kg live weight. Feed conversion ranged from 1.2 to 1.8 kg DM/kg live weight gain in the first period and from 2.3 to 3.2 kg DM/kg live weight gain in the last period. The digestibility of the energy in the rations with a crude protein content of between 17 and 24% averaged 80% and that of the rations with a crude protein content of 44-47% averaged 86%. In the course of ontogenetic development the digestibility increased up to about 30 kg LW. The influence of the nutritional level on the level of digestibility was unequal in the experiments. In one experiment a decrease (1% unit) and in two experiments an increase (1-3% units) of the digestibility after the feeding of growth level in contrast to maintenance level could be observed. The change of rations with a varying protein content did not result in an influence on the digestibility level in comparison with the constant feeding of one ration.     

Basic data on food intake, nutrient digestibility and energy requirements of lorikeets

Although knowledge of the nutrient requirements of pet birds has increased a lot over the last few years, basic data on food and water intake and the energy requirements of nectarivorous species, such as lorikeets, are scarce. Thus, the aim of this study was to try to generate some of these data for lorikeets kept at maintenance. Determination of the daily maintenance energy requirement enables calculation of the daily ration and thus, the appropriate nutrient concentrations in order to maintain body weight. Investigations were carried out with six Goldie's lorikeets (GL; Trichoglossus goldiei: 40-50 g BW; 1-4 years) and six rainbow lorikeets (RL; Trichoglossus haematodus haematodus: 120-140 g BW; 1-12 years). Three of the most commonly used diets/foods (commercial 'lory soup'/apples/pollen: crude ash - 52.9/17.8/18.8; crude protein - 178/32.5/191; crude fat - 52.8/0.89/73.1; crude fibre - 17.9/40.5/30.4; starch - 139/not detectable/127; sugar - 522/859/418 g/kg DM; ME - 13.9/14.6/10.9 MJ/kg DM) were individually offered ad libitum. The measured dry matter (DM) intake (g/100 g BW) corresponded well to the values reported for granivorous bird species of similar body mass. Both lorikeet species achieved an apparent digestibility of organic matter of more than 90% for apples, approximately 82% for 'lory soup' and approximately 55% for pollen. The water content of the food affected the DM content of the excreta; 8% when fed 'lory soup', 2% for apples and approximately 30% when fed pollen. Regression analysis of body weight change relative to energy intake demonstrated constant body mass (assuming no change in body composition) when the daily energy intakes were 860 (GL) or 650 (RL) kJ ME/kg BW(0.75).     

The use of ribonucleic acids as markers for the measuring of microbial protein yield in the rumen. 2. The effect of sample treatment, the time of sampling and the composition of the ration on the RNA:N ratio in rumen microbes]

In two experiments the influence of the treatment of samples, the sampling time and the composition of the rations on the RNA: N ratio in the rumen microbes was checked. Experiment I proved that freezing (-21 degrees C), thawing and freeze-drying of isolated bacteria and protozoa from the rumen fluid and from the duodenal content did not result in a change of the RNA content and the RNA-N: total N relation. If, however, the rumen fluid is stored deep-frozen before the isolation of the bacteria the N content in the DM of the bacteria decreases by 17% and that of RNA by 30%. This results in a change of the RNA: N relation of 16%. In conclusion, the bacteria are to be isolated immediately after rumen fluid sampling. Isolated bacteria can be stored deep-frozen before RNA determination and then freeze-dried. Experiment II showed that the RNA content of the rumen protozoa varies according to the period after feeding. The RNA: N relation was 0.50, 0.92, 0.70 and 0.58 on average 0, 3, 6 and 8 h after feeding, in which the 3rd hour after feeding can obviously be considered the time of increased microbial activity. The conclusion from this variation is that more than one isolation of microbes must be carried out in the course of the day in order to achieve representative samples. These statements apply to easily and not easily fermentable protein as N source in the feed. It could also be proved that no essential variation is to be expected in the RNA: N relation in the microbes isolated from the rumen fluid in the range of 8-21% crude protein in the DM of the ration (roughage: concentrate = 55: 45). On average the rumen microbes contained 1.7 g RNA-N/16 g N, essential differences between bacteria and protozoa could not be ascertained. From the slight variation of the RNA-N: N relation in the isolated bacteria from various cows one can conclude that there is no need to isolate the microbes of each individual animal.     

The effects of different sources of nitrogen supplementation on the post ruminal flows of organic matter and different nitrogenous constituents in steers

Friesian steers, virtually protozoa free, were equipped with simple rumen and abomasal cannulas. They were given diets consisting of approximately equal proportions of ground, pelleted alkali treated straw and a rolled barley, tapioca mixture supplemented with urea + casein (UC), soybean meal (SBM), 'normal' white fishmeal (NDF) or white fishmeal designated as being of 'low' rumen degradability (LDF). The diets were isoenergetic (the protein sources replacing part of the tapioca) and they were given in amounts to supply sufficient metabolizable energy (ME) to support an average growth rate of 0.5 kg/d. Rumen degradable nitrogen (RDN): ME values were estimated to be 2.08, 1.40, 1.90 and 1.66 for diets UC, SBM, NDF and LDF respectively. RNA, alpha-epsilon-diaminopimelic acid and 35S (added as sulphate) were used as bacterial markers. Chromic oxide 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. Rumen volumes and ruminal liquid fractional outflow rates were measured using PEG. Samples of mixed rumen bacteria separated from strained rumen digesta from animals receiving diet UC contained significantly less DAP-N (0.322 g/kg DM) than those from animals receiving diets SBM, NDF or LDF (0.530 g/kg DM). Mean rumen volume (approximately 15 l) and liquid fractional outflow rates (approximately 0.105/h) were similar on all diets but there was appreciable variation between animals. The proportion of OM intake digested in the rumen was similar on all diets. The proportional contribution of bacterial-N to the total non-ammonia-N passing the abomasum based on mean values derived from DAP and 35S as markers was 0.57, 0.47, 0.39 and 0.31 for diets UC, SBM, NDF and LDF respectively. Corresponding values based on RNA were 0.71, 0.50, 0.48 and 0.35 respectively. Bacterial-N (RNA) flows at the abomasum were 31, 25, 26 and 20 g/d for diets UC, SBM, NDF and LDF respectively. Corresponding values for 35S and DAP were 26, 24, 21 and 18 g/d respectively. Values derived from RNA flows were consistently and significantly higher (P less than 0.01) than those based on DAP or 35S. Mean estimated efficiencies of bacterial protein synthesis (g bacterial-N/kg OM truly digested) were 15, 15, 14 and 12 for diets UC, SBM, NDF and LDF respectively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of supplementing Rhodes grass hay (Chloris gayana) with Berchemia discolor or Zizyphus mucronata on the performance of growing goats in Kenya

Twenty growing Small East African goats were used to determine the effects of feeding sun-dried leaves of the browse forages Berchemia discolor and Zizyphus mucronata as supplements to low-quality basal diet, Rhodes grass (Chloris gayana) hay, on voluntary feed intake (VFI), digestibility and growth performance. The grass hay and maize bran were used as a control. The dried leaves were then included at the rates of 15% and 30% of the dry matter intake (DMI). Berchemia discolor had the highest crude protein (CP) content of 195.5 g/kg DM, while Z. mucronata had CP content of 169.5 g/kg DM. The grass hay had the lowest CP content of 50.9 g/kg DM. The browse forages had low fibre content [Neutral detergent fibre (NDF); 257.9-369.5 g/kg DM], while the grass hay had high fibre content (NDF; 713.1 g/kg DM). Goats in the groups supplemented with either of the browse forages had higher total DMI, nitrogen (N) intake and retention and live-weight gains than those in the control diet group. The digestibility of DM and organic matter (OM) was not affected by supplementation, but the CP digestibility increased with supplementation. The use of the browse forages as supplements for goats fed on poor-quality basal diets would enhance the performance of the animals.