Pelleted Ration Research Articles

Ovarian follicle populations and ovulation rates of Finnish Landrace cross ewes in different nutritional states and associated profiles of gonadotrophins, inhibin, growth hormone(GH) and insulin-like growth factor-I

Effects of ewe body condition and level of feed intake on ovarian follicle populations and ovulation rates were studied in three groups of 12 to 15 Finnish Landrace cross ewes. Ewes were fed to achieve target body condition scores of either 2.0 (low, LM) or 2.5 (moderate, MM) and then fed a complete pelleted ration for three weeks before study so that they maintained liveweight. Ewes of a third group were also fed to achieve condition scores of 2.5 and then fed ad libitum (MAL). Neither ewe body condition nor level of feed intake significantly affected either the number of large follicles (≥ 4 mm diameter) or the ovulation rate. The proportion of estrogenic follicles was lower in MM than LM ewes (0.77 vs. 0.96; P < 0.05), but there was no difference in this proportion between MAL and MM ewes. Insulin-like growth factor-I (IGF-I) concentrations in the follicular fluid were unaffected by ewe body condition or level of feed intake despite significant treatment differences in circulating concentrations. Inhibin concentrations were higher in estrogenic follicles of LM compared with MM ewes, and this difference was reflected in circulating profiles. Treatment differences in LH profiles were not associated with any difference in follicle populations or ovulation rate. There were no consistent treatment effects on FSH concentrations. It is concluded that the roles of inhibin and IGF-I in the control of follicle development cannot be adequately assessed on the basis of circulating concentrations alone and that there is a need to measure intrafollicular hormone profiles and associated effects on follicle physiology.

Growth, Yield, and Dress-out Percentage of Diploid and Triploid Channel Catfish in Earthen Ponds

Abstract Fingerling diploid (mean ± SD: 63 ± 14 g) and triploid (45 ± 17 g) channel catfish (Ictalurus punctatus) were stocked into 0.04-hectare earthen ponds at a density of 11,000 fish/hectare, with three replicate ponds for each ploidy level. Fish were fed a pelleted commercial catfish ration (32% protein) to satiation daily. Ponds were drained and fish harvested after 185 d. No significant differences were found between diploid and triploid catfish for harvest weight and dress-out percentage; however, triploids had significantly (P < 0.05) lower survival and yield, and higher feed conversion (weight of feed fed/weight gain) than diploids. Macroscopic examination of gonads revealed the expected lack of sexual development and gonadal maturation in triploids.

Effect of season and nutrition on scrotal circumference of Merino rams

In 3 experiments, groups of 5 Merino rams were individually fed a pelleted ration at maintenance (1 kg/day), with or without 750 g/day of lupin grain, and kept indoors under conditions of natural light and temperature. Measurements of scrotal circumference and liveweight were made during winter, spring-summer and autumn, for periods of 42-49 days. Ambient temperatures and daylengths were recorded. The season of the experiment affected the rate of change of scrotal circumference. Rams fed the maintenance diet showed a pattern of increasing scrotal circumference, starting in late spring after the spring equinox and reaching a maximum in autumn-early winter, then decreasing in mid-late winter after the winter equinox. Scrota1 circumference responded to increased nutrition under all daylength regimes and the magnitude of this response was influenced by the season.

Effect of meal feeding on plasma volume and urinary electrolyte clearance in ponies

SUMMARY The effect of meal size and frequency on plasma volume, plasma aldosterone concentration and urinary Na and K clearances was determined in ponies. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen, ie, 12 equal portions fed at 2-hour intervals, or as single large feedings, ie, half the ration fed every 12 hours at 0800 and 2000 hours. Only the effect of the single morning feeding was studied, using the latter regimen. Serial measurements of plasma volume were made by use of an indicator-dilution technique and indocyanine green (0.15 mg/kg of body weight, iv) that allowed repeated determinations at 2-hour intervals. Ingestion of the single large meal caused a 15% decrease in plasma volume by the end of a 1-hour feeding period. Feeding hypovolemia was confirmed by a coincident increase in plasma protein concentration (12%) and, in separate experiments, by analysis of postfeeding changes in the elimination of Evans blue dye. Plasma aldosterone concentration was significantly (P &lt; 0.05) increased from 2 to 5 hours after feeding. Urinary Na clearance decreased in response to feeding and remained lower than the prefeeding value until 9 hours after feeding. Urinary K clearance increased from prefeeding and reached a peak value between 5 and 7 hours after feeding. Creatinine clearance was unaffected. In contrast, the aforementioned variables were unchanged during the multiple regimen. Results indicate that ingestion of a large concentrate meal by ponies causes periprandial hypovolemia, activation of the renin-angiotensin-aldosterone system, and a subsequent antinaturesis-kaluresis that lasts for several hours.

Effect of ambient temperature and urea supplementation on the intake and digestion of alkali-treated straw by Brahman cattle and swamp buffaloes

SUMMARYFour adult swamp buffaloes (Bubalus bubalis) and four adult Brahman cattle (Bos indicus), maintained in climate rooms, were provided ad libitum with a pelleted NaOH-treated barley straw ration (10·7 g N/kg dry matter) supplemented with sulphur, minerals and vitamins and 0, 14·5 or 22 g urea/kg. The animals were given each diet when housed at 32 °C and, in addition, were given the urea unsupplemented diet at 22 °C. All animals received all treatments for periods of 21 days, measurements being made during the last 8 days, after the animals had been given single doses of two nonabsorbable markers (Cr-fibre and Co-EDTA). Intake, digestibility and gastro-intestinal passage rate were low on the unsupplemented N-deficient (10·7 g N/kg dry matter) diet at both temperatures. Urea supplementation to provide diets of 17·3 and 20·7 g N/kg dry matter was associated with increased intake and digestibility of the feed and increased rate of passage of digesta through the gut.Despite differences in respiration rate and plasma thyroxine (T4) and triiodothyronine (T3) concentrations at the two temperatures, no effects of temperature on intakes and digestion of the unsupplemented diet were seen. Differences between species were seen in respiration rate at 32 °C and plasma T4, which were higher, and mean retention time of Cr in the gut at 22 °C and water intakes, which were lower, in Brahman cattle than in buffaloes. There were no significant species differences in response to dietary urea supplementation.

EFFECT OF FEED TEMPERATURE ON COLD SUSCEPTIBILITY OF CATTLE AND SHEEP

The metabolic heat production of steers was measured at ambient temperatures of +10, −8 and −20 °C following their consumption of 15-kg turnip bulbs (Brassica napus) with a temperature of 27, 2 or −8 °C, or 10-kg turnips with a temperature of 2 °C followed by 1 kg hay. Metabolic heat production was elevated 13–80% after eating the cold and frozen turnips when steers were exposed to −8 °C and 35–80% when exposed to −20 °C. Sheep fed 20, 35, 55, 80 and 110 g pelleted ration per kg−0.75 d−1, accompanied by a ruminal infusion of water at 38 or 2 °C at a volume required to simulate a 10% dry matter feed had their metabolic heat production measured at +10 and −20 °C. Heat production was significantly increased at −20 °C for only the 2 °C infusion although with the 38 °C infusion at the lower feed intake levels, metabolic heat production was higher by up to 37% at an ambient temperature of −20 °C than at +10 °C. The lower critical temperature of the steers after ingestion of the turnips was estimated to be −4.5, −2.4, +3.2 and +13.9 °C forthe27, 2 + hay, 2 and −8 °C turnips, respectively. The lower critical temperature of sheep was raised by 1, 11, 31, 25 and &gt; 22 °C by the ruminal infusion of water at 2 °C compared to water at 38 °C in sheep fed 20, 35, 55, 80 and 110 g feed kg−0.75 d−1, respectively. Key words: Cold, temperature, heat production, cattle, sheep

Effects of nutrition and paring on linear hoof growth in sheep

Paring increased the linear hoof growth on the forefeet of Merino wethers by an average of 4.1% (P &lt; 0.05) with a tendency for paring to promote faster growth on the medial digits. Effects of feeding these sheep with 400, 600, or 1000 g pelleted ration day-1 were assessed in a 4 X 4 Latin square design with 28-day periods using four measures of response. An extra (fifth) period was used to determine residual effects. The proportion of residual (carryover) to direct effect was much smaller for hoof growth than for wool. Hoof growth was not related to wool production. In another experiment, hoof growth rate of sheep increased from 103 to 136 8m day-1 when the intake of digestible dry matter was increased from 400 to 600 g day-1 (P&lt; 0.001), and from 115 to 125 8m day -1 (P&gt; 0.05) when the intake of digestible nitrogen was increased from 12 to 25 g day-1. Hoof growth rates of Merino wethers grazing native or sown pasture were not significantly affected by injecting DL-methionine daily into the abomasum. Hoof growth is not an appropriate index of wool growth. It may provide an easily measured, rapidly responsive and cumulative measure of nutritional changes, but its use cannot be recommended until more information is available on the factors that affect it and their interaction with ambient temperature.

Untersuchungen zum Stickstoffumsatz im Dickdarm von Wiederkäuern

Two wethers (28 kg and 33 kg) were supplied with ileocaecal re-entrance cannulae and received a straw pellet ration rich in crude fibre (70.5% straw, 12% chopped sugar beet, 10% cereals, 2% urea, 3% NH4HCO3 and 2.5% of a mineral mixture). In a preliminary period 50% of the digesta flow was collected on 6 successive days for 18 h each. An amount of digesta sufficient for 24 h was apportioned for hourly application and stored at a temperature of -20 degrees C for the main trial. In the main trial the two animals received intracaecally the collected digesta with a supplement of ca. 6 g hay damaged by heat/kg LW(0.75) in hourly portions over 24 h (hay made up ca. 15 and 20% resp. of the DM amount). In addition, each digesta sample was supplemented with 14C and 15N labelled urea (19.7.10(6) Bq 14C urea and 364 mg 15N excess from 15N urea). About 9% of the applied 15N amount was microbially utilized; the utilization quota was thus lower than after the application of partly hydrolyzed straw meal (16% in a previous trial). The 14C activity from 14C urea was quickly eliminated in the form of CO2 in the respiratory gases (at the 18th hour after the end of the infusion 70% excreted as CO2). The half-lives for the urea resulting from the semi-logarithmic decrease of the atom-% 15N excess in the blood plasma were 7.9 and 7.7 resp. 23% and 34% resp. of the applied 15N excess were excreted in urine. The excretion of radioactive carbon in urine, however, was at 2.8% and 4.3% resp. of the applied amount very low 120 h after the beginning of the trial (96 h after the end of the infusion). On the whole one can conclude from this trial that hay damaged by heat has only a low stimulating effect on microbial activity in the large intestine.

Effects of diet and feeding on postprandial serum gastrin and insulin concentration in adult horses.

Gastrin is the only hormone known to stimulate secretion of hydrochloric acid. It also has trophic effects on specific parts of the mucosa of the gastrointestinal tract. Using radioimmunoassay techniques, postprandial serum gastrin and insulin concentrations were measured in six adult horses to establish effects of different diets on gastrin concentrations. Insulin concentrations were measured to provide support to the patterns of gastrin secretion because patterns of insulin secretion were already known. The horses were fed coastal bermuda hay, or twice daily 5 kg of a complete pelleted ration, 5 kg of commercial sweet feed or 5 kg of the sweet feed together with hay. There was little change in serum gastrin or insulin concentrations after feeding hay alone. Rations containing more readily available nutrients (pellets, sweet feed) produced significant increases in postprandial serum gastrin and insulin concentrations. Gastrin concentrations also varied according to the duration of feeding each diet, but this was not seen with insulin. These results indicated that gastrin secretion, and therefore possibly gastric acid secretion, were markedly influenced by dietary composition and duration of feeding a diet. There appeared to be some adaptation of the stomach (gastrin secretion) to changes in diet, but this was not accompanied by indications of adaptation in the endocrine pancreas (insulin secretion).

Seasonal body weight, body condition, and lactational trends in muskoxen

Seasonal patterns of body weight, fat, protein, milk quality (dry matter content), and milk production rate were determined for three sexually mature female muskoxen (Ovibos moschatus) over three consecutive lactation periods. Females were allowed to graze in summer and had access to hay year-round. A high-protein pelleted ration supplemented this diet. Following calving in early May (1984, 1986) or June (1985), body weight remained constant throughout the summer, body fat declined for 3–5 weeks after calving, and body protein declined transiently during the latter period. Almost all annual gains in body weight and body fat occurred during the 6- to 8-week rutting period from mid-August to mid-October. High milk production (1.3–2.4 L/d) occurred 3 weeks post-calving, generally remained high for another month, and declined to 1.2 ± 0.15 L/d (mean ± SEM) just before the rut. A major decline in milk production, to 0.44 ± 0.050 L/d, occurred during the rut. Although milk dry matter increased 33% ± 4.3% during the rut, this increase was offset by the 60% ± 6.4% decline in milk production. All females successfully reproduced each year of the study and no evidence was found for a lactational anestrum. The hypothesis that gains in body weight must be made before the rutting period to maximize conception rate was rejected. This study highlighted the importance to lactating muskoxen of the late summer – early winter period for annual regain in body weight and body fat, which occurred concurrently with ovulation and conception.

Effect of limited-creep feeding on performance of spring-born calves: results of 1988 field trials (1989)

Two field trials were conducted to evaluate limited-creep feeding of spring- born calves using pelleted creep rations with either 0.5, 5, or 10% salt. Average daily gain was increased (P<.05) over controls in trial 2 and when both trials were combined. However, intakes were higher than desired and feed conversion much poorer than expected.

Lupins and energy-yielding nutrients in ewes. II. Responses in ovulation rate in ewes to increased availability of glucose, acetate and amino acids.

An experiment, using a total of 320 Merino ewes, over two successive breeding seasons was conducted to investigate the separate effects of energy-yielding and protein-yielding nutrients on ovulation rate in sheep. The available energy-yielding or protein-yielding nutrients in the blood of sheep fed a maintenance pelleted ration were increased by either intravenous infusions of metabolites (acetate, glucose or acetate + glucose), feeding lupin grain, modification of the pattern of rumen fermentation to increase propionate production using the ionophore, lasalocid, or by feeding of ruminally undegradable protein (formaldehyde-treated casein). All treatments were given for 9 days prior to and including expected time of ovulation. Ovulation rates were measured by laparoscopy. In the first season (the 1984 experiment) when the effects of lupin grain, glucose + acetate and formaldehyde-treated casein were compared, ovulation rates were increased significantly in the group fed lupin (29%, P less than 0.001) and the group infused with glucose + acetate (24%, P less than 0.01). There was an apparent (17%) but statistically non-significant increase in the group fed casein. In comparisons between lupin grain, glucose, acetate, glucose + acetate, formaldehyde-treated casein and lasalocid in the 1985 experiment there were similar significant increases in ovulation rates in the groups fed lupin, and those infused with glucose or glucose + acetate (approximately 25%, P less than 0.001). The increase in the group infused with acetate was lower at 14% (P less than 0.05) and the increases of 7% in the groups fed casein or lasalocid were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of diet and cold exposure on captive female mourning doves dosed with lead shot.

The effects of diet and cold exposure on captive female mourning doves (Zenaida macroura) dosed with lead (Pb) shot were investigated from 12 December 1985 to 2 January 1986. Doves were screened for Pb exposure using a blood delta-aminolevulinic acid dehydratase assay. A 2×2× 2 factorial design was employed with Pb (1 #8 Pb shot {70±0.5 mg} or seed), temperature (5°C or 22°C), and diet (commercial pelleted ration or mixed seed) as the three factors of interest. Ninetysix doves were assigned randomly to 1 of the 8 treatments, confined individually, and acclimated to their respective diets 3 weeks prior to dosing.

Effect of feeding on renin-angiotensin-aldosterone system of the horse.

The effect of feeding frequency and associated meal size on the renin-angiotensin-aldosterone system (RAAS) in seven horses was examined. A daily maintenance ration of hay-grain pellets was provided either as a multiple feeding regimen (MF), in which the ration was divided into six equal portions fed at 4-h intervals, or as a single large feeding (SF) given from 9 A.M. until 11 A.M. Plasma renin activity (PRA), aldosterone (PAC), cortisol (PCC), protein concentration (TP), packed cell volume (PCV), and serum sodium and potassium were measured serially. To prevent significant RAAS stimulation due to strenuous exercise or by assuming orthostatism after a period of recumbency, the horses were trained to stand in 1 X 4-m tie stalls during the experiments. Changes in Na intake were prevented by disallowing nonration salt sources. A 12:12 light-dark interval was maintained. During the MF experiment, only serum Na changed diurnally, with concentrations lowest in early morning and highest before midday. In contrast, during the SF experiment, PRA was increased at 0.5, 1.0, and 3.0 h and PAC was increased at 3.0, 5.0, and 7.0 h after onset of feeding (P less than 0.005). Increased TP and PCV suggested transient hypovolemia was responsible for renin release. Significant increases in Na and decreases in K occurred while eating; however, K increased postprandially to be coincident with aldosterone. Except for a transient increase during feeding in SF, PCC demonstrated a similar circadian rhythm in both experiments. It was concluded that 1) episodic feeding (SF) causes significant diurnal variation of the RAAS in the horse, and 2) spontaneous circadian activity of the RAAS cannot be demonstrated in this species during a steady-state feeding regimen (MF).

Feed additives for attracting sheep to eat a pelleted diet during assembly for live export

The failure of some sheep to eat pelleted feed in feedlots prior to export may result in subsequent problems in their health and welfare. We investigated ways of improving feeding behaviour by adding chaffed hay or aromatic compounds to the pelleted feed. A control ration of pellets was compared with the same diet sprayed with solutions of butyric acid, aniseed oil or molasses, or fed with chaff (lucerne or oaten). Measurements of the number of sheep eating and total feed intake were made over a 10-day period. Merino wethers from 3 properties were mixed and allocated into 2 replicate groups of 39 animals per yard (1 3 m2/sheep) for each of the 6 treatments. The patterns of feed intake over time fell into 2 distinct groups. Over 70% of sheep fed pellets with either type of chaff visited the feed trough during the first 24 hours. When no chaff was fed, this level of feeding was achieved only after 4 days. All groups fed pellets without chaff showed the same pattern of feed intake, reaching a peak intake on day 3 or 4 before reducing intake until day 6 and then an increasing intake up to day 10. Little sign of this fluctuation was seen in the animals fed pellets with chaff, suggesting that, when only pellets were fed, an unstable pattern of rumen fermentation may have caused a build-up of lactic acid in the rumen and reduced feed intake. Molasses and aniseed reduced (P&lt;0.01) the percentage of sheep per day visiting feed troughs to 5 1 and 53% respectively (6-day mean) compared with 63 and 62% for sheep on unsprayed pellets and pellets sprayed with butyric acid. Over the 10 days, intake of total feed per sheep putting its head in the trough was 1.10 kg/day for sheep fed pellets only while aniseed caused a reduction (P&lt;0.01) to 0.85 kg/day and lucerne chaff resulted in an increase (P&lt; 0.05) to 1.27 kg/day. There were significant differences in the eating pattern between different sources of sheep (P&lt; 0.001) but there were no interactions between source and dietary treatments. We conclude that adding chaffed hay to the feed troughs can maximise the proportion of sheep eating from the first day in the feedlot. In addition, mixing chaffed hay with pellets on the first few days may assist the transition from roughage to cereal based diets. The use of aromatic compounds was not successful in attracting animals to the feed or in encouraging an increased intake.

The effect of weight stasis on the dissected carcass composition of crossbred sheep

A study was made of the dissected carcass composition of crossbred wethers (progeny of Dorset Horn rams and Border Leicester x Merino ewes) maintained at 30 kg liveweight for either 0, 25, 50 or 75 days. Animals were individually penned and fed a pelleted ration of 80% lucerne chaff and 20% cereal grain (89.3% dry matter, I4.8To crude protein and 18.27 kJ/g gross energy). Cold carcass weight showed a significant increase (P &lt; 0.05) in animals during weight stasis, although dry matter intake of animals during weight stasis decreased. All dissected carcass fat depots increased during weight srasis, although only subcutaneous fat showed a significant increase (P &lt; 0.05) in weight. Neither the weight of total dissected side muscle nor total dissected side bone was affected by weight stasis. Only the weight of Standard muscle group 1 showed a significant response to weight stasis, and it increased (P &lt; 0-05). Weight stasis had no effect on the weights of separate bones. Results for fat, muscle and bone distribution are reported. Subcutaneous fat formed a significantly increasing proportion of total side fat weight (P &lt; 0.05) as duration of weight stasis increased, while intermuscular fat showed a trend to form a decreasing proportion. Weight stasis had no effect on the proportion of total side muscle formed by each of the Standard muscle groups, except group 4 which decreased (P &lt; 0.05). Bone distribution was not influenced by weight stasis.

The effect of weight stasis on the non-carcass components of crossbred sheep

A study was made of the non-carcass components of 16 crossbred wethers (progeny of Dorset Horn rams and Border Leicester x Merino ewes) maintained at 30 kg liveweight for either 0,25, 50 or 75 days. Animals were individually penned and fed a pelleted ration of 80% lucerne chaff and 20% cereal grain (89.3% dry matter, 14.8% crude protein and 18.27 kJ/g gross energy). The weight of hooves increased significantly (P &lt; 0.05) during weight stasis, while the weight of the liver decreased significantly (P &lt; 0.001) as did the weight of the kidneys (P &lt; 0.01). Neither head, skin, heart, lungs, spleen, pancreas nor total alimentary tract fat weight was influenced by weight stasis. The separate parts of the alimentary tract did not respond to the weight stasis treatment in the same manner. The weight of the rumen-reticulum, small intestine and large intestine each showed a significant reduction (P &lt; 0.001) in weight. In contrast, neither omasum nor abomasum weight was affected by weight stasis. Total alimentary tract weight was significantly reduced (P &lt; 0.001) by weight stasis. An evaluation of the weights of digesta in the separate parts of the alimentary tract showed that the weight of omasal contents increased significantly (P &lt; 0.01) during weight stasis, while small intestine contents weight decreased significantly (P &lt; 0.01). The weight of contents in either the rumen-reticulum, abomasum, large intestine or total alimentary tract was not influenced by weight stasis.

Dynamics of amino acid and protein metabolism of laying hens after the administration of 15N-labeled wheat protein. 1.Problems, research program and 15N-labeling of urine

In a 6-day preliminary period with a pelleted ration 12 colostomized laying hybrids received 15N labelled wheat protein over 4 days. The labelling of the wheat was 14.37 atom-% 15N excess (15N'). During the 4-day application of 15N wheat protein each hen consumed 12.08 g nitrogen, 3.52 g lysine, 2.12 g histidine, 4.41 g arginine, of which were 540 mg 15N', 18.1 mg lysine 15N', 21.5 mg histidine 15N' and 47.9 mg arginine 15N'. Heavy nitrogen was determined in urine and its uric acid-N in the daily urine samples of the individual animals. The average daily urine N excretion was 54% of the total nitrogen consumed with the ration. The labelling of the urine N reached a plateau on the fourth day of the experiment with 3.2 atom-% 15N'. On an average of the total experiment the quota of heavy nitrogen of the uric acid in the total 15N' of the urine was 83.4% and that of uric acid nitrogen in the total urine nitrogen 80.8%.

Effect of meal schedules and fasting on selected plasma free amino acids in horses.

The effects of meal frequency and fasting on selected plasma free amino acids (PFAA) was studied in horses. Six 22-mo-old Quarter Horses were used in a replicated 3 X 3 Latin-square design in which each horse received one meal per day (1M), two meals per day (2M) or six meals per day (6M) for 2 wk. A complete pelleted ration was fed at a rate of 1.75% of body weight daily. The consumption of a meal by the horses fed 1M and 2M daily was followed by an increase (P less than .05) in plasma methionine. The highest levels were observed at 5 h and 3 h in the 1M and 2M treatments, respectively. The horses receiving the larger meal (1M) also had higher methionine levels. There were no significant changes in plasma methionine levels in the 6M group. Feed was withheld from the 1M group for 48 h and blood samples were obtained for alanine, glutamine, glutamate, lysine and leucine levels. These amino acids also peaked at 5 h, then declined through 19 to 25 h. During the last 24 h PFAA levels increased (P less than .05). Although glutamine and lysine appeared to level off at 49 h after the meal, alanine, glutamate and leucine were still increasing.

Nitrogen metabolism in the large intestine of ruminants. 2. Metabolism of i.v. infused 15N-urea by additional supply of fermentable material to the large intestine of bulls

The experiment was carried out on 3 bulls with body weights of 201, 168 and 190 kg, respectively. The animals were equipped with a ileo caecal re-entrant cannula and with catheters in the jugular veins on both sides. The pelleted ration was composed of straw 70-72%, cereals 10%, molasses 12-41%, ammoniumhydrogencarbonate 3%, urea 2% and mineral mixture 1%. During a preliminary period ileal digesta were collected, deep-freezed and stored. During the main experiment 15N-urea was infused intravenously for 24 hours. In this period and during the following 6 hours outflowing ideal digesta were collected quantitatively. At the same time precollected, unlabelled digesta together with a supplement of partly hydrolysed straw meal were reintroduced into the caecal part of the cannula. Plasma urea-N, urinary-N as well as several N-fractions of faeces and digesta were analysed for 15N abundance. A urea flux rate of 27.9 +/- 3.4 mumol per minute per kg 0.75 was estimated. It was calculated that 52% of this amount of urea was transferred into the digestive tract. In both, digesta and faeces NH3-N was highest 15N-labelled indicating a direct urea entry and degradation in both segments of the digestive tract. The amounts of 15N-excess found during the period of digesta replacement were in faeces 0.25 and in ileal digesta 4.02% of the infused amount of 15N. Although the microbial utilization of endogenous urea-N was generally low in the large intestine there was a clear stimulation of this process due to the additional supply of the large intestine with a fermentable source.