Cellulose fermentation capacity of the hindgut and nitrogen turnover in the hindgut of sows as evaluated by oral and intracecal supply of purified cellulose

Adult sows fed a constant amount of a basal diet received purified cellulose either orally at levels of 0 and 475 g/animal.d (Experiment 1) or intracecally at levels of 0, 285, 570 and 855 g/animal.d (Experiment 2). Each experiment consisted of subsequent periods of faeces and urine collection with the animals re-allocated to the treatments each time. With that, a total of 36 observations on each parameter was achieved. The faecal samples were analyzed for the contents of organic matter, cell wall carbohydrates and various nitrogen fractions such as bacterial N and undigested dietary N. Furthermore, N balance, urinary allantoin excretion and plasma urea concentrations were determined. In a preliminary study, the effects of freeze-drying and of shaking of the faecal samples as suspensions with water (in order to release bacteria from fibre) on content and composition of faecal nitrogen had turned out to be reproducible. Cellulose significantly enhanced faecal nitrogen loss whereas N retention was not affected due to the counteraction of urinary N loss. Plasma urea concentration reflected the situation with urinary N. The proportion of undigested dietary N and of water-soluble protein in total faecal N was somewhat increased by cellulose at cost of the bacterial N proportion which accounted for about 72% of total N on average. Urinary allantoin did not respond to the higher bacterial activity in the hindgut in the presence of supplementary cellulose. Cellulose significantly decreased the apparent N digestibility by on average about 3 percentage units per 100 g of supplementary cellulose. True N digestibility was also reduced by cellulose but did not go below 95%. The supplementary cellulose was fermented in the hindgut at similar rates of on average about 60% regardless of the route of administration. The almost 100 g of native cellulose incorporated in the basal diets were lignified by about 20%, and that is why they were fermented at a rate of only about 30%. The rate of fermentation was only slightly decreasing with increasing amounts of supplementary cellulose, and a daily quantity of 564 g (11 g/W0.75) cellulose was fermented on average if the highest level of cellulose was provided. This was within a range exclusively reported for easily-fermentable carbohydrates but was achieved in the case of cellulose only at a consistently higher level of supply. The true efficiency of bacterial protein synthesis was 5.2 g bacterial protein/100 g supplementary cellulose on average. The apparent efficiency was 60% higher averaging 8.4 g bacterial protein/100 g further apparently fermented organic matter.     

Studies on the protein and amino acid metabolism of laying hens using 15N labeled casein. 4. Fecal excretion of nitrogen and amino acids, digestibility of crude protein and absorption of basic amino acids]

Generally, the faeces of laying hens fed 15N casein rations were found to contain equal proportions of TCE-precipitable and TCE-soluble nitrogen. Considerable variations were observed to occur between the 64 samples investigated (27%-75%) and no explanation was found to account for this fact. The content of basic amino acids in faecal proteins was found to differ considerably from that of the proteins in the intestinal contents. A high lysine content was found after the feeding of wheat. The present trial substantiated this result, provided the casein contained a certain proportion of non-available lysine. The apparent and true digestibility of dietary N was 88% or 91%, that of 15N (2nd and 6th day of experiment) and 92%. During the feeding of labelled casein a higher level of N labelling was found in the TCE-soluble portion of the faeces, whereas on the 8th to 12th day a higher level of labelling was observed in the TCE-precipitable portion of the faeces. The peak of 15N excretion occurred on the 3rd day of experiment. When 15N administration terminated the atom% 15N in the faeces and in urine was found to decrease rapidly approximating the initial level of labelling asymptotically.     

Dietary carbohydrates affect caecal fermentation and modify nitrogen excretion patterns in rats. II. Studies with diets differing in protein quality.

In 2 two-factorial experiments, each conducted on 80 growing male rats, the effects of substituting 10% raw potato starch (PS), pectins (PEC), or cellulose (CEL) for wheat starch (WS) and the addition of tannic acid to WS (WSTA) were studied using diets differing in protein quality. Casein unsupplemented or supplemented with DL-methionine and gluten unsupplemented or supplemented with lysine, methionine and tryptophan were used as protein sources in Experiment 1 and 2, respectively. Parameters indicative of caecal fermentation intensity (pH, acetic, propionic and butyric acid contents, digesta and tissue weight) and of protein metabolism (urea blood concentration, faecal and urinary nitrogen excretion) were determined. Ten-day balance experiments were preceded by a 10-day adaption period to respective carbohydrates given in a diet containing balanced protein. In both experiments the type of carbohydrates affected the caecal concentration of individual and total SCFA and other parameters of fermentation intensity. Pectins and potato starch were fermented more intensively than cellulose. Faecal N excretion was increased by all carbohydrates substituted for cereal starch, and by tannic acid. Urinary excretion was greater on CEL than on PEC and WSTA containing casein and on other diets containing gluten. In both experiments urinary N excretion was the lowest on PEC diets. Protein quality had the greatest effect on apparent biological value and net protein utilization but all indices of protein utilization were also affected by carbohydrates. It is concluded that not only the amount of N excreted in faeces but also in urine is affected by the type and fermentability of carbohydrates.     

Dietary carbohydrates affect caecal fermentation and modify nitrogen excretion patterns in rats. I. Studies with protein-free diets.

In a two-factorial experiment on 96 young male rats, the effects of substituting 10% raw potato starch (PS), pectins (PEC), or cellulose (CEL) for corn starch (CS) were studied using an unsupplemented protein-free (PF) diet or a PF diet supplemented either with DL-methionine or urea. The pH and the short chain fatty acids (SCFA) content in caecal digesta, as well as caecal digesta and tissue weights were determined and used as the criteria of caecal fermentation intensity. Blood urea level, amount of N excreted via faeces and urine, DAPA content, and amino acid composition of faecal protein were analyzed as indices of protein metabolism. A 10-day adaptation period to the carbohydrates fed with the casein diet preceded the experimental period of feeding the respective carbohydrates with protein-free diets. Dietary carbohydrates significantly influenced total and individual SCFA content in caecal digesta, as well as other parameters related to the intensity of fermentation. Potato starch and pectins were more intensively fermented than cellulose. Supplementation of the PF diet with methionine and urea affected only caecal isobutyric and valeric acid content in a way dependent on the carbohydrates present in the diet. Carbohydrates significantly altered the routes of N excretion. Faecal excretion was increased by all carbohydrates studied compared to corn starch, pectins had the most marked effect. Urinary excretion was significantly increased by cellulose (as compared with the PEC and PS groups) and decreased by pectins as compared with all other groups. There was an interaction between the effects of carbohydrates and type of protein-free diet on faecal and urinary excretion. The sum of amino acids in faecal protein was the lowest on the PEC diet, but the amino acid composition expressed as a per cent of total amino acid content was similar in all groups. It can be concluded that dietary carbohydrates alter the excretion patterns of endogenous nitrogen in rats in different ways and that this effect is related to the intensity of their fermentation in the hind gut.     

Dietary lactulose decreases apparent nitrogen absorption and increases apparent calcium and magnesium absorption in healthy dogs

To study the effect of lactulose on the route of nitrogen excretion, we fed six healthy, adult dogs on diets containing either 0, 1 or 3 g lactulose/MJ metabolizable energy according to a 3 × 3 Latin square design. The results were analysed to identify statistically significant linear trend effects of lactulose. Faecal pH was significantly lowered by lactulose. Faecal ammonium and nitrogen excretion tended to be raised by lactulose feeding whereas urinary urea excretion was significantly reduced. Lactulose feeding significantly lowered apparent nitrogen digestibility. It is concluded that lactulose feeding shifts nitrogen excretion from urine to faeces in dogs which may be beneficial for liver patients. The data are in line with the concept that lactulose stimulates bacterial growth in the colon which in turn enhances faecal nitrogen excretion and lowers the entry of colonic ammonia into the bloodstream, leading to a lesser workload for the liver and less urinary nitrogen excretion. Lactulose consumption was also found to produce a dose-dependent increase in the apparent absorption of calcium and magnesium, but not phosphorus.     

Effect of thermal treatment of potato products on nutrient decomposition in the digestive tract of swine. 1. Passage and digestibility of nutrients in the various portions of the intestine

In addition to a basic ration (barley, dried green fodder, fishmeal) pigs (castrated males, 100 ... 130 kg live weight) received a supplement of raw potato starch, raw ensiled potatoes, cooked potato starch or steamed ensiled potatoes; nutrient and amino acid passage and digestibility (absorption) were measured in the small intestine, the upper large intestine and the total digestive tract with the help of simple cannulae at the distal ileum and the middle of the hind gut and the estimation of the HCl insoluble ash as an indicator. In addition, the amounts of bacteria in faeces were determined and the influence of raw and cooked potato starch on N retention was ascertained. When raw potato products were fed, distinctly higher amounts of dry matter, organic matter and starch pass the ileum, which get into the colon undigested, i.e. the digestibility of these substances is low at the end of the ileum (raw potato starch 24%, starch of raw ensiled potatoes 36%). Up to the middle of the colon there is intensive bacterial starch degradation so that in this place the difference between raw and thermically treated potatoes is only small. No matter what the previous treatment of the potatoes was, there is hardly any starch in faeces, i.e. it was nearly 100% digested up to the end of the digestive tract. The passage and digestibility resp. of ash and crude cellulose from the basic ration is not influenced by the supplement of raw or thermically treated potato products in the individual sections of the digestive tract. At the end of the ileum there are no differences between the apparent digestibility of the crude protein and absorption of amino acids of supplemented raw or cooked potato starch or steamed ensiled potatoes; after the use of raw ensiled potatoes they are, however, significantly more reduced than the comparison of analyses of faeces shows. In the large intestine the high amount of potato starch stimulates the metabolism and the reproduction of faecal bacteria as is shown by an increase by 20-30% in bacteria N excretion in faeces. Apparent crude protein digestibility and amino acid absorption are diminished by that. The increased N excretion in faeces after the supplement of raw potato starch to the basic ration is-in comparison with the supplement of heated starch-compensated by a commensurately lower N excretion in urine so that N retention practically remains uninfluenced by the supplement of variously treated potato starch.(ABSTRACT TRUNCATED AT 400 WORDS)     

Macronutrient digestibility, nitrogen balance, plasma indicators of protein metabolism and mineral absorption in horses fed a ration rich in sugar beet pulp

In a cross-over study with six mature horses, the effect of iso-energetic replacement of dietary glucose by beet pulp on macronutrient digestibility, nitrogen metabolism and mineral absorption was studied. The test ration contained 25% beet pulp in the total dietary dry matter. Beet pulp feeding significantly lowered crude fat and non-structural carbohydrate digestibility, but had no significant effect on digestibility of other macronutrients, faecal and urinary nitrogen excretion and the faecal to urinary nitrogen excretion quotient. However, on the beet pulp diet, plasma ammonia and creatinin concentrations were significantly lower than on the glucose diet. No diet effect on magnesium absorption was observed. It is suggested that dietary beet pulp stimulates the conversion of ammonia into urea.     

Influence of cellulose fibre length on faecal quality,mineral excretion and nutrient digestibility in cat

In dogs, faeces quality and nutrients digestibility were affected by different types of cellulose ( Wichert et al., 2002 ). In this study, it was investigated whether there are comparable effects of cellulose type in cats. Seven adult, healthy cats were fed a moist commercial complete cat food with three different cellulose type added at a level of 4% for a 1 week period. Faeces quality was between 1 and 3 on the scale used from 1 to 5. The addition of long fibre cellulose resulted in significantly firmer faeces. Addition of cellulose decreased the digestibility of dry matter and energy, whereas the impact on protein and fat digestibility was not significant. The type of cellulose affected faecal bulk and faecal water excretion. Faecal excretion of sodium and potassium was exponentially correlated to faecal water, faecal bulk and to a lesser extent to faecal dry matter excretion. Faecal calcium, magnesium and phosphorus excretion showed an exponential correlation to faecal dry matter excretion. A weaker correlation existed in all three elements to faecal bulk, whereas the effect of faecal water excretion was small. Results suggest a remarkable likeness between cats and dogs with regard to the digestive physiology of major minerals.     

Nutrient digestibility and nitrogen utilization in lactating cows under restricted protein supply and subsequent refeeding

The effects of a 17% deficiency of crude protein for four weeks on nutrient digestibility and parameters of N metabolism were investigated using four pairs of monozygotic twin cows. During a period of realimentation of three weeks with slight nutrient oversupply and a further period of three weeks with nutrient supply adjusted to the lactation trend it was examined if residual effects remain. Protein restriction enhanced the excretion of fecal dry matter by 7.7%. Total fecal nitrogen was a high in the restricted group as in the control group. Apparent digestion coefficients for dry matter, organic matter and N-free extracts were lowered by 2 to 3 percent points with deficient protein nutrition. Crude fiber and nitrogen digestibilities declined by 4.5 and 9.8 percent points, respectively. The reduction of urine nitrogen excretion amounted to 47% as consequence of a drastically diminished nitrogen content of urine. Total nitrogen retention (milk-N and body-N) was lowered by 14%. The sum of the relative nitrogen losses via faeces and urine was not different between the protein-deficient and the normal diet. The utilization of feed nitrogen for milk nitrogen excretion was 28.2% in protein deficiency and 25.9% in control feeding. After realimentation no relevant residual effects of the previous protein deficiency were found neither with respect to nutrient digestibility nor to parameters of the nitrogen balance. So far the observed permanent effect in reduced milk yield by 6% of the expected performance can not be explained with changes in digestibility or nitrogen balance.     

Effect of fructo‐oligosaccharide on nitrogen utilization in guinea pigs

The present study was conducted to determine the effects of fructo‐oligosaccharide (FOS) on the nitrogen (N) utilization and digestibilities of dietary nutrients through cecotrophy in guinea pigs. Adult male guinea pigs that were housed or not housed in wooden frames to prevent cecotrophy were fed a commercial pellet diet (50 g/day) with 3% and 5% glucose or FOS for 8 days in individual metabolism cages. In the guinea pigs allowed cecotrophy, addition of FOS to the diet had no significant effects on body weight gain or apparent digestibility of N, but showed significantly lower value for the urinary N excretion and acid‐detergent fiber digestibility (P < 0.05 and P < 0.01, respectively) and significantly higher value for N retention and the N retention rate (P < 0.05). In the guinea pigs prevented from cecotrophy, FOS had no effect on N retention, but showed tendencies toward a higher value for fecal N excretion and a lower value for urinary N excretion. These results suggest that FOS stimulates cecal microbial proliferation, thereby improving N utilization in guinea pigs.     

不同精粗比日粮对青年母水牛尿中嘌呤衍生物排出规律的影响

试验选取3头24月龄、体重相近的健康母水牛,采用随机区组试验设计,分别饲喂象草22.93kg+精料1.19kg/d(处理A)、象草18.63kg+精料2.07kg/d(处理B)和象草14.33kg+精料2.96kg/d(处理C)3种不同精粗组合的试验日粮。结果表明:随着精料水平的上升,营养物质的表观消化率呈递增趋势(P<0.05);粪氮和尿氮呈递减趋势(P<0.05);氮平衡和能量消化率明显增加(P<0.01);尿中PD的排出量显著升高(P<0.05);肌酸酐的排出量稳定在40mmol/d左右,各处理间无显著差异(P>0.05)。     

饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响

本试验旨在研究饲喂高淀粉饲粮时不同瘤胃降解淀粉水平对奶牛泌乳性能、营养物质表观消化率和氮平衡的影响。选用10头荷斯坦经产奶牛[平均泌乳天数为(214±38)d,平均乳产量为(26.2±2.4)kg/d,平均体重为(727±65)kg]作为试验动物,随机分成2组,每组5头。试验设计2种不同瘤胃降解淀粉水平的试验饲粮,分别为瘤胃降解淀粉水平为62.3%(占总淀粉的百分比)的低瘤胃降解淀粉水平饲粮(L-RDS)和瘤胃降解淀粉水平为72.1%(占总淀粉的百分比)的高瘤胃降解淀粉水平饲粮(H-RDS)。采用交叉试验设计,试验分为2期,过渡期7 d,每期试验21 d,其中适应期14 d,采样期7 d。结果显示:1)相比L-RDS组,H-RDS组有机物和淀粉的表观消化率显著升高(P0.05),中性洗涤纤维和酸性洗涤纤维的表观消化率显著降低(P0.05),干物质表观消化率有升高趋势(P=0.07),蛋白质表观消化率无显著差异(P0.05)。2)相比L-RDS组,H-RDS组尿素氮及它们占摄入氮比例有降低趋势(P=0.09),摄入氮、乳氮、粪氮、尿氮和沉积氮及它们占摄入氮比例无显著变化(P0.05),尿中总嘌呤衍生物排出量和微生物蛋白产量亦无显著变化(P0.05)。3)饲粮瘤胃降解淀粉水平对奶牛干物质采食量、乳产量和乳成分均无显著影响(P0.05)。综合以上结果可知,饲喂高淀粉饲粮时不同瘤胃降解淀粉水平影响饲粮营养物质的表观消化率,对泌乳性能和氮平衡无显著影响。     

日粮蛋白质水平对断奶仔猪氮代谢的影响

试验研究了日粮不同蛋白质水平对断奶仔猪氮代谢的影响。试验采用完全随机设计,将72头35日龄断奶的仔猪分为4组,每组3个重复,每个重复6头。4个组分别饲喂24%、22%、20%、18%蛋白水平的日粮。结果表明:粪氮排泄随日粮蛋白水平的升高而增加,24%蛋白组粪氮排泄量显著高于其它3组(P<0.05),尿氮变化不显著;22%、20%、18%蛋白组氮表观消化率无显著差异,24%蛋白组氮表观消化率显著低于其它3组(P<0.05);氮代谢率随蛋白水平上升而下降;血清总蛋白浓度与日粮蛋白水平无显著的相关性;血清尿素氮浓度随日粮蛋白水平的降低而降低。总之,考虑到仔猪生长和氮排出,仔猪日粮蛋白水平应以20%~22%为好,18%的日粮蛋白水平影响仔猪日沉积氮量。     

The substitution of lysine supplemented high protein wheat for protein feeds during the rearing and laying periods of hens. 8. Nitrogen excretion and true amino acid digestibility as an effect of various lysine levels and successive laying periods]

Digestibility trials were performed with laying hens receiving 3 types of rations containing equal proportions of the same dietary components. The percentage of high-protein wheat in these rations was 74%. Ration I was supplemented with 0.12% lysine while 0.06% lysine was added to ration II; ration III remained unsupplemented. The crude protein content of rations 1 to 3 was 16.1%, 16.5% and 16.6%, respectively. The corresponding lysine percentages were 0.66, 0.62 and 0.56. Studies were made to investigate the influence of different lysine levels on the rate of N excretion and various amino acid data. These studies were carried out during two successive laying periods. Only random differences between the data for urinary N excretion and N balances per kg liveweight were obtained in the two laying periods and for the different lysine levels. The true lysine digestibility was significantly lower in the poor-lysine ration as compared with the ration with 0.66% lysine. Moreover, the absorptive capacity for thio-amino acids is influenced by the lysine level of the ration. The proportion of lysine contained in faecal crude protein increased with the decreasing lysine content of the ration. Similarly, the total number of amino acids present in faecal crude protein increased with the declining supply of lysine. These findings suggest that relatively more NPN compounds are excreted in the faeces if adequate amounts of amino acids are supplied rather than when one amino acid is deficient.     

Milk production,nutrient digestibility and nitrogen balance in lactating cows fed total mixed ration silages containing steam‐flaked brown rice as substitute for steam‐flaked corn,and wet food by‐products

The objective of this study was to evaluate the effect of substituting brown rice grain for corn grain in total mixed ration (TMR) silage containing food by‐products on the milk production, whole‐tract nutrient digestibility and nitrogen balance in dairy cows. Six multiparous Holstein cows were used in a crossover design with two dietary treatments: a diet containing 30.9% steam‐flaked corn (corn TMR) or 30.9% steam‐flaked brown rice (rice TMR) with wet soybean curd residue and wet soy sauce cake. Dietary treatment did not affect the dry matter intake, milk yield and compositions in dairy cows. The dry matter and starch digestibility were higher, and the neutral detergent fiber digestibility was lower for rice TMR than for corn TMR. The urinary nitrogen (N) excretion as a proportion of the N intake was lower for rice TMR than for corn TMR with no dietary effect on N secretion in milk and fecal N excretion. These results indicated that the replacement of corn with brown rice in TMR silage relatively reduced urinary N loss without adverse effects on feed intake and milk production, when food by‐products such as soybean curd residue were included in the TMR silage as dietary crude protein sources.     

Effects of straw treatment and nitrogen supplementation on digestibility,intake and physiological responses of water intake as well as urine and faecal characteristics

This study investigates the effects of feeding diet based on untreated (UT) or ensiled alkali‐treated (ET) barley straw with either urea or casein supplementation, on feed intake, digestibility, ruminal pH, water intake and faecal and urinary characteristics. Four sheep fitted with ruminal cannulas were used in a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Barley straw was treated by the dry (spraying) method in pH adjusted of hydrogen peroxide (pH 11.5), ensiled for 6 weeks and included at 65% of the diet dry matter (DM). The results showed that straw pH reduced from 11.58 to 8.60 after 6 weeks of ensilage. The ET diet increased average DM digestibility and intake by 19% and 43% respectively. Total water intake was similar across treatments, while the water/DM intake ratio was 23% higher with the UT diet than with the ET one. Ruminal (6.73 vs. 6.84) and faecal (8.67 vs. 9.05) pH decreased but urinary pH (6.14 vs. 8.13) increased as a result of feeding animals on the ET diet compared with the UT diet. Compared with the UT diet, the ET one decreased faecal fibre (12%), moisture (32%) and water holding capacity, while it increased faecal ash (10%) and density (20%). The volume of urine excreted by the sheep fed with the ET diet increased by 67%, but their urine specific gravity (SG) decreased. No significant effects were observed for the dietary N supplementation and interactions between straw type × N supplementation with regard to any of the measured characteristics except for DM intake, which reduced due to the casein supplementation in the ET diet. These results indicate that the alkali treatment and ensilage of barley straw increased digestibility, intake, faecal consistency and urinary pH and dilution but decreased straw alkalinity as well as ruminal and faecal pH.     

Effects of urinary excretion of nitrogen, potassium and sodium on urine volume in dairy cows

Data of 50 balance measurements were collected from dry and lactating Holstein cows to clarify the effects of urinary excretion of nitrogen (N), potassium (K) and sodium (Na) on urine volume in cows. In dry cows, orchardgrass silage, timothy hay, alfalfa silage and corn silage were offered to meet the TDN requirement. Orchardgrass silage or alfalfa silage diets were offered in switch back trials in lactating cows. There were no relationships between urinary excretion and plasma concentrations of K or Na in cows, but urinary N excretion increased with the increase of plasma urea nitrogen. There was positive correlation between urinary excretion and urinary content of Na, but urinary K contents increased rapidly by 1.3% with the increasing urinary K excretion and thereafter remained almost constant. The increasing urinary K and N excretion enhanced urine volume in cows, but urine production in cows was accurately estimated from the regression equation of urine K excretion on urine volume. Urine volume was not affected by urinary Na excretion. These results suggest that the increase of urine volume in cows affected by the increasing urinary excretion of K and N may be due to the maintenance of urine or plasma osmolality.     

Fibre analysis and fibre digestibility in pet foods--a comparison of total dietary fibre, neutral and acid detergent fibre and crude fibre

Six dry dog foods and six dry cat foods with different carbohydrate sources were investigated in digestion trials. Food and faecal samples were analysed for CF, TDF and starch. In dogs, also neutral detergent fibre (aNDFom) and acid detergent fibre (ADFom) were analysed. N-free extract (NfE) was calculated for CF, and similarly for all other fibre analyses. Linear regressions were calculated between fibre intake and faecal fibre excretion. True digestibility was calculated from the regression coefficients [true digestibility in % = (1 - regression coefficient)*100], with the intercept of the equation representing excretion of material of non-food origin. Crude fibre analyses gave the lowest values, and TDF the highest, while ADFom and aNDFom were in between. Variation between diets was lowest in CF and highest in TDF. Total dietary fibre, aNDFom and ADFom in food were positively correlated. Crude fibre in food did not correlate with any other method. The NfE analogue for TDF was closest to the starch content. Methods of fibre analyses in faeces did not agree very well with each other. Crude fibre had the lowest apparent digestibility, followed by ADFom, TDF and aNDFom. For all fibre analyses, there was a significant correlation between fibre intake and faecal fibre excretion. True digestibility was close to zero for CF, with a high uniformity in both species. In dogs, true digestibility of aNDFom was 53%, of ADFom 26% and of TDF 37%; in cats, true digestibility of TDF was 31%. Except for CF, the intercept of the regression equations suggest that faecal excretion of some material of non-food origin is analysed as fibre. A combination of TDF and CF analyses might give good information on the content of total (TDF), unfermentable (CF) and partially fermentable fibre (TDF-CF) in pet foods.     

The substitution of protein feed by lysine supplemented high protein wheat during the rearing and laying period in hens. 9. True amino acid digestibility of rations with varying lysine levels in hens who had a colostomy]

24 experimental birds were fed the same basal ration containing 74% high-protein wheat, 4% extracted soya bean meal, 7% extracted groundnut meal, 2% feed yeast, 1.75% dried green meal, 1.25% mixed vitamins and 10% of a mineral mixture. The birds were placed in 4 groups each comprising 6 hens. The first two groups received an optimum of lysine (0.68%) added to the ration. The rations for the two other groups contained 0.55% lysine. 6 birds of each group receiving either the lysinesupplemented or the unsupplemented rations were colostomated to investigate in which way the hydrolysed urine would affect the true amino acid digestibility. 8.3% of urinary N from the total amount of faecal N were precipitated as uranyl acetate in the faeces of hens fed the lysine-supplemented ration as compared with 7.3% urinary N in birds receiving the unsupplemented ration. The corresponding figures for non-precipitable faecal N were 8.9% and 8.2%. A comparison was made between the levels of amino acids excreted by colostomated and non-colostomated hens showing that 12.4% +/- 3% and 11.7% +/- 3% more amino acids (figures for the supplemented and unsupplemented rations) were excreted in the presence of urine. On the basis of these results the authors recommend that only colostomated hens should be used in digestibility and total metabolism trials.     

Faecal bacterial profile,nitrogen excretion and mineral absorption in healthy dogs fed supplemental oligofructose

In a cross-over trial, five healthy dogs were fed a dry food without or with 1% (w/w) oligofructose to assess any oligofructose-induced effects on the faecal bacterial profile, nitrogen excretion and mineral absorption. The diets were given for a period of 3 weeks. Oligofructose feeding significantly raised the number of Bifidobacteria, Streptococci and Clostridia in faeces. The numbers of faecal anaerobic and aerobic bacteria were raised after ingestion of oligofructose. The faecal pH was unchanged. There was no effect of oligofructose feeding on the route of nitrogen excretion which was associated with a lack of effect on faecal ammonium and urinary urea excretion. It is suggested that the absence or presence of an effect of oligofructose on urinary and faecal nitrogen excretion depends on the background composition of the diet, in particular the content of non-digestible, fermentable carbohydrates. In the diets used, the content of non-digestible, fermentable carbohydrates was not measured. Both apparent magnesium and calcium absorption were significantly raised by oligofructose feeding, but phosphorus absorption was unaffected. The data presented may contribute to the qualification of the use of oligofructose in dog foods.