Intake and ruminal digestion determined using omasal and reticular digesta samples in cattle fed diets containing sugar cane in natura or ensiled sugar cane compared with maize silage

Sugar cane is widely used in an in natura forage in tropical countries, but the adoption of silage methods facilitates the preservation of its nutritional value and improves the logistics of its use. To explain differences in performance using alternative forages, it is important to conduct studies that evaluate the various digestion sites for the nutrients provided in diets. However, considering that the collection of omasal digesta is quite laborious and requires the use of a vacuum pump, reticular sampling has been suggested as a promising alternative. Thus, the objective of this study was to evaluate the intake and ruminal digestibility obtained from samples of digesta collected in the reticulum and omasum of cattle fed different diets. Five rumen-fistulated crossbred cattle with an average initial live weight of 336±16.6 kg were used, being distributed in a 5×5 Latin square design. Five diets were evaluated, which contained 60% forage and 40% concentrate on dry matter basis using different forages: maize silage (CS); sugar cane in natura (SCIN); sugar cane silage (SCS0%); sugar cane silage treated with 0.4% calcium oxide (SCS0.4%) or 0.8% calcium oxide (SCS0.8%) on wet basis. The percentage of crude protein (CP) in all of the forages was corrected to 11% based on dry matter (DM) using a mixture of urea/ammonium sulfate (9:1). Six collections of reticular and omasal digesta were obtained over three days at 12 h intervals. To calculate the flow of reticular and omasal nutrients, a double marker system was employed, using cobalt–EDTA and indigestible neutral detergent fiber (NDFi) as markers. The reticular and omasal digesta were similar (P>0.05) to estimate ruminal digestibility of DM, organic matter (OM), CP, neutral detergent fiber (NDF) and non-fiber carbohydrates (NFC). However, the ruminal digestibility of ether extract (EE) and the intestinal digestibility of CP and EE differed (P<0.05) between sampling sites. The results indicate that the omasal digesta is more suitable than the reticular digesta for measuring the ruminal digestion of diet components.     

Postileal nutrient digestibility in cattle]

Four heifers of an average live weight of 301 kg supplied with ileocaecal re-entrant cannulae received rations consisting of 4 kg hay (variants A und B), 1 kg coarse wheat meal, 0.4 kg molasses, 100 g urea and 30 g mixed minerals per animal and day. After a 14-day preliminary feeding period the ileum digesta was quantitatively collected at the re-entrant cannula over 24 h. 10% of the digesta were used for analysis, the remainder was heated to 37 degrees C and returned. Under consideration of the digesta passage through the colon the 24-hour collection of faeces was started after a 6-hour delay after the first replacement of digesta. Losses of nutrients were calculated from the values analysed from digesta and faeces. No differences could be ascertained between the two hay variants. On an average of the two rations the nutrient losses of the scaffold substances-equivalent to the digestibility in the colon-showed the following values: crude fibre = 10.6%, NDF = 10.4%, ADF = 11.9% and hemicellulose = 7.4%. The losses of the other nutrients, corresponding to their apparent digestibility, had the following values: crude protein = 12.1%, crude fat = 10.7%, N-free extracts = 18.9%, ash = 31.2%, dry matter = 17.5%. The water balance showed that 8.2 l water of the 23.4 l supplied with the ileum digesta were excreted in faeces.     

Copper,iron, zinc and tannin concentrations throughout the digestive tract of tropical goats and sheep fed a high-fibre tannin-rich diet

The dry season in tropical regions urges livestock to feed on nutritionally very poor diets. It has not been explored how tropical sheep—assumed grazers—and tropical goats—intermediate browsers—cope with a high-fibre tannin-rich diet. This study was designed to determine the effects of a high-fibre and tannin-rich diet on the flow of important microminerals iron (Fe), zinc (Zn) and copper (Cu) throughout the digestive tract of tropical sheep and goats. The feeding trial was set up with twelve adult male animals, six sheep with mean body weight (BW) of 30.3 ± 1.6 kg and six goats with mean BW of 26.4 ± 2.2 kg. The feed consisted of 36% leaves of Millettia ferruginea, 61% hay and 3% concentrate and was offered at 3% of BW (all on dry matter (DM) basis). The total faecal collection was carried out for 7 consecutive days. At the end of the experimental period, the animals were slaughtered to collect liver and digesta samples from the gastrointestinal tract. Feed, digesta and faecal samples underwent analysis of Fe, Zn, and Cu and total tannins (TT). Goats had significantly higher reticulum Cu concentrations expressed on DM as compared to sheep. Faecal Cu concentrations were higher for goats compared to sheep. Reticulum and colon digesta Zn levels were higher in goats than sheep. Abomasum and colon Fe levels were higher in sheep than goats when expressed on DM. These results suggest differences in feed intake, micromineral absorption, secretion and excretion between sheep and goats, pointing to a divergent mineral metabolism as an adaptation to the challenge of a dry season diet having very low nutritive value.     

The effect of feeding different protein-free diets on the recovery and amino acid composition of endogenous protein collected from the distal ileum and feces in pigs

Nine barrows with an average initial weight of 60 kg were fitted with simple T-cannulas at the distal ileum. The animals were fed four different protein-free diets according to an incomplete latin square design. Diet 1 (control diet) consisted of 79.7% cornstarch, 10% sucrose, 3% Alphafloc (a source of cellulose), 3% canola oil and a vitamin-mineral premix. Diets 2, 3 and 4 contained, respectively, 4% pectin, an additional 7% cellulose and an additional 10% canola oil, each included at the expense of cornstarch. Feces were collected during 3 d following a 7-d adaptation period. Thereafter, digesta were collected during two 24-h periods with a 24-interval between periods. The pigs were fed 800 g of feed twice at 0800 and 2000. Added pectin increased (P less than .05) the recovery of endogenous protein in ileal digesta from 19.8 diet (diet 1) to 24.0 g per kg dry matter intake. This increment was largely due to increases (P less than .05) in glycine and proline from 1.9 to 2.4 and from 6.2 to 8.4 g per kg dry matter intake, respectively. In feces, only added cellulose increased (P less than .05) excretion of endogenous protein (8.4 vs 11.1 g/kg DM intake) and of most amino acids. Including additional fat did not affect the quantity of endogenous protein and amino acids recovered in ileal digesta or feces. Small but significant differences (P less than .05) were observed in the amino acid composition of endogenous protein recovered in ileal digesta when the different protein-free diets were fed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fiber digestion in various segments of the hindgut of horses fed grass hay or silage

We studied in vivo fiber digestibility and fermentation parameters such as volatile fatty acid concentration and in vitro degradation in each segment of hindgut of horses fed timothy hay or silage made from the same sward. Six Thoroughbred horses were fed timothy hay or silage in equal amounts (1.6% of bodyweight per day, bodyweight mean 572 kg) every 3 h per day, then slaughtered. There were no differences between hay and silage in the concentration of the total volatile fatty acids, the apparent digestibility of dry matter, organic matter, and fiber, and in vitro neutral detergent fiber (NDF) disappearance rate in each segment. The total volatile fatty acid concentration and the apparent digestibility of dry and organic matter and fiber differed ( P  < 0.01) depending on the digestive segments. Both for hay and silage, the concentration of total volatile fatty acids in the digesta liquid phase largely increased ( P  < 0.01) from the cecum to the right ventral colon, and kept a constant value from the right ventral colon to the right dorsal colon, and then decreased from the right dorsal colon to the small colon. For dry and organic matter and fiber components, the apparent digestibility changed in the same manner from former to hinder segments of the hindgut. Regardless of diet, dry and organic matter and fiber components showed lower values in the cecum and the right ventral colon and increased ( P  < 0.01) largely from the right ventral colon to the left dorsal colon, then kept constant values in segments to the rear of left dorsal colon. There were no differences in in vitro NDF disappearance among cecum, ventral colon and dorsal colon.     

Dry matter and digesta particle size gradients along the goat digestive tract on grass and browse diets

Physical properties of the digesta vary along the ruminant digestive tract. They also vary within the forestomach, leading to varying degrees of rumen contents stratification in ‘moose‐type’ (browsing) and ‘cattle‐type’ (intermediate and grazing) ruminants. We investigated the dry matter concentration (DM) and the mean digesta particle size (MPS) within the forestomach and along the digestive tract in 10 goats fed grass hay or dried browse after a standardized 12‐h fast, euthanasia and freezing in the natural position. In all animals, irrespective of diet, DM showed a peak in the omasum and an increase from caecum via colon towards the faeces and a decrease in MPS between the reticulum and the omasum. Both patterns are typical for ruminants in general. In the forestomach, there was little systematic difference between more cranial and more caudal locations (‘horizontal stratification’), with the possible exception of large particle segregation in the dorsal rumen blindsac on the grass diet. In contrast, the typical (vertical) contents stratification was evident for DM (with drier contents dorsally) and, to a lower degree, for MPS (with larger particles dorsally). Although evident in both groups, this stratification was more pronounced on the grass diet. The results support the interpretation that differences in rumen contents stratification between ruminants are mainly an effect of species‐specific physiology, but can be enhanced due to the diet consumed.     

The effect of protein status of the pig on the recovery and amino acid composition of endogenous protein in digesta collected from the distal ileum

Barrows with an average initial weight of 55 kg were fitted with simple T-cannulas at the distal ileum. The animals were fed a protein-free diet that consisted of 79.7% cornstarch, 10% sucrose, 3% Alphafloc (a source of cellulose), 3% canola oil and a vitamin-mineral premix. The pigs were fed 700 g of diet twice each day, at 0800 and 2000. A balanced amino acid mixture or a saline solution was administered intravenously while the protein-free diet was fed. Ileal digesta were collected for 24 h following a 7-d adaptation period. The administration of amino acids reduced (P less than .05) the recovery of endogenous protein from 18.5 to 12.7 g per kg dry matter intake. For the amino acids, the reduction was only significant (P less than .05) for proline, from 3.6 to .6 g per kg dry matter intake. If the total endogenous protein losses are assumed to be constant and the differences in the amino acid composition of non-reabsorbed endogenous protein, as observed in this study, are used to calculate true ileal digestibilities, differences in the digestibilities of the indispensable amino acids are large (up to 7.4 percentage units for threonine). The amino acid composition of endogenous protein determined in pigs fed a protein-free diet and parenterally administered with amino acids should provide a better estimate for the calculation of true amino acid digestibilities when based on the determination of true protein digestibility by the 15N-isotope dilution technique.     

The effect of Lupinus albus seeds on digestibility,performance and gastrointestinal tract indices in pigs

The effect of soya bean meal (SBM) substitution in the diet with white lupine (WL) seeds on performances and some parameters of the digestive tract of pigs were studied. The digestibility experiment was performed on 30 pigs using difference method combined with marker method, where one group was offered basal diet and in diet of experimental groups 25% of the basal diet was substituted with SBM or WL meal. The growth experiment was conducted on 48 pigs of approximately 20 kg body weight. The animals from the control group were fed with diet containing SBM, whereas in the experimental groups 50% or 100% of SBM was substituted with WL seeds. At the end of the experiment, eight pigs from each group were euthanized, and digesta and tissues were sampled. The apparent total tract digestibility of crude protein and dry matter was higher (p < 0.05), but crude fibre and ether extract were lower (p < 0.05) in the WL seeds than in SBM. Substituting 50% of SBM in the control diet with WL seeds did not affect significantly pig performance. Total substitution of SBM with WL seeds impacted negatively pigs growth and feed intake (p < 0.05), but it did not affect the length of villi and crypt depth. It also significantly increased ileum digesta viscosity and ammonia concentration in the ileum and caecum digesta. In the ileal digesta of animals offered WL seeds, an increased (p < 0.05) total bacterial and Enterobacteriaceae numbers were found, whereas reduced number of yeast and mould was found in the caecal digesta. The substitution of 50% SBM with WL seeds in the growing pig diet did not affect pigs' results, but the total substitution significantly decreased the performance of pigs and affected intestinal ecology.     

Digestive physiology of captive giant anteaters (Myrmecophaga tridactyla): determinants of faecal dry matter content

Giant anteaters (Myrmecophaga tridactyla) are specialized insectivores and consume mainly ants and termites in the wild. In captivity, giant anteaters are either fed a complete diet, or a combination of a domestic carnivore diet with leaf eater pellets, or a traditional gruel‐type diet. Soft faeces are a frequently encountered problem with this type of feeding. In the present study, we analysed diet and faeces composition, calculated digestibility and measured mean retention time on various diets in eight giant anteaters (total of n = 64 experiments). The results suggest that the digestive physiology of giant anteaters is similar to that of domestic dogs and cats in terms of nutrient digestibility and digesta retention. When testing correlations between faecal dry matter content and other variables, no relationship with dietary crude fibre content or mean digesta retention time could be detected. However, acid insoluble ash intake was significantly and positively correlated with faecal dry matter content. The amount of acid insoluble ash excreted with the faeces was higher than that ingested with the diet offered, indicating that the giant anteaters ingested soil from their enclosure of up to 93 g per day. This finding is consistent with observation of faeces of wild giant anteaters that contain soil or sand most likely due to indiscriminate feeding. It also corresponds to reports that indigestible materials such as peat, soil, chitin or cellulose contribute to a firmer faecal consistency in various carnivore species. Therefore, offering giant anteaters the opportunity to voluntarily ingest soil from their enclosure might be beneficial.     

Determination of physical characteristics,chemical composition and digestion coefficients of treated lemon pulp with Saccharomyces cerevisiae in goat diet

The aim of this study was to evaluate the effects of processing of lemon pulp with Saccharomyces cerevisiae on physical properties, chemical composition, digestion coefficients and blood parameters. Eight adult male Raeini goats were used in a 28‐day period. The experimental design was a completely randomised design with two treatments and four replicates. The first 21 days were for adaptation, and the last 7 days were for collecting samples. The animals were housed in individual metabolic cages equipped with a urine–faeces separator and were fed with diet containing alfalfa hay (60%) and lemon pulp (40%) at the maintenance level. Collected data were subjected to analysis of completely randomised design. With diet containing processed lemon pulp, functional specific gravity, bulk density, soluble dry matter, percentage of crude protein, neutral detergent fibre (NDF), acid detergent fibre and crude ash were significantly increased and water‐holding capacity, insoluble dry matter, insoluble ash percentage of dry matter, organic matter, crude fat, non‐fibrous carbohydrates and nitrogen‐free extract were significantly decreased (p < 0.05). Digestion coefficient of organic matter in dry matter and metabolisable energy were also decreased in treated lemon pulp (p < 0.05). Compared with untreated lemon pulp, digestibility of crude protein and NDF was higher (p < 0.05), but digestibility of crude fat was lower (p < 0.05). In general, processing of lemon pulp with S. cerevisiae improved the physical characteristics and increased the percentage of crude protein and the digestion coefficients of protein and NDF.     

Anatomical parameters of the body and the digestive tract of Callithrix sp. marmosets under the influence of seasonality

Due to the ecological importance and given the scarcity of studies on the digestive morphology of primates, anatomical aspects of the body and digestive tract, as well as food content were analysed for marmosets Callithrix sp. (hybrids of exotic species) captured in forest fragments in Minas Gerais - Brazil, during the dry and rainy seasons, considering that seasonal variations affect the availability of food and quality of diet. Data such as body weight and length, and thoracic and abdominal perimeters were analysed, and no significant difference was found between dry and rainy seasons. In relation to the digestive tract, length, weight and diameter of the oesophagus, stomach, small intestine and large intestine were measured, in addition to the isolated caecum. There was a significant difference in the diameter of the ascending colon, which was larger in the animals in the dry season than in the rainy season. The difference found may be related to diet, and through analysis of the gastric and caecal contents, it was observed that gum was the main food item for the dry season marmosets, while in the rainy season the animals consumed mainly arthropods. Thus, the characteristic observed in the digestive tract of dry season marmosets is a reflection of an adaptive response to gum intake, since this food item is of low digestibility, necessitating that the food content be retained for a long time in this segment of the large intestine, helping the process of microbial fermentation and better energy utilization for these animals.     

Replacement of soybean meal with levels of inclusion of soya waste in the diet of growing goats

An experiment was conducted to investigate the effect of replacing soybean meal with soya waste at different levels on intake, digestibility and growth in goats. Eighteen male goat kids with initial body weight (BW) of 13.0 kg were distributed equally to three dietary groups. They were fed Napier grass (Pennisetum purpureum) and concentrate mixture, and each goat was assigned to an individual pen. Soybean meal in the concentrate mixture was replaced with soya waste at 0% (T1), 50% (T2) and 100% (T3) levels in respective dietary groups. These diets were isocaloric and isonitrogenous. Results showed that animals fed T3 diet exhibited higher Napier grass intake than those fed T1 or T2 diet. There was no influence on total intakes of dry matter (DM), organic matter (OM), crude protein (CP), metabolic BW, per cent BW and metabolisable energy by the dietary groups. However, there was an increasing trend on intake and digestibility of neutral detergent fibre (NDF) with increasing levels of soya waste in the diets. Animals fed T3 diet showed higher intake and digestibility of NDF than those fed T1 diet. There was no influence of the dietary groups on digestibilities of DM, OM and CP. Similarly, there was no effect of them on the final BW, total BW gain, daily BW gain, feed conversion ratio and feed cost. Soya waste can replace 100% soybean meal in diets for growing goats, because no change was observed in nutrient intake, digestibility and growth performance; inclusion of soya waste enhanced the intake and digestibility of NDF.

     

Feed intake and digestion by beef cows fed prairie hay with different levels of soybean meal and receiving post-ruminal administration of antibiotics

Six cannulated beef cows (one Angus, two Hereford and three Angus x Hereford; 405 kg) were used in a 6 x 6 latin square experiment with a 2 x 3 factorial arrangement of treatments. Prairie hay (.77% N, 73% neutral detergent fiber [NDF] and 7% acid detergent lignin) was fed ad libitum from d 1 through 14 and at 90% of ad libitum intake from d 15 through 21 during digesta collection. Periods lasted 21 d. Soybean meal (SBM) was offered at 0 (control, C), .12 (low, L) or .24% of body weight (high, H; dry matter basis). Cows received daily doses of an antibiotic mixture (1 g neomycin and .125 g bacitracin) or saline in the duodenum. Prairie hay dry matter (DM) intake increased (P less than .05) linearly with SBM supplementation, being 25 and 40% greater for L and H than for C, respectively. Ruminal fluid concentrations of NH3-N and total volatile fatty acids increased (P less than .05) linearly as SBM was added to the diet. Ruminal fluid dilution rate increased linearly and particulate passage rate increased (P less than .05) quadratically with increasing SBM. True ruminal digestibilities of organic matter, NDF and N increased (P less than .10) quadratically with increasing SBM (organic matter; 50.3, 57.9 and 58.3%; NDF: 54.7, 60.4 and 59.8%; N: 17.5, 45.1 and 51.4% for C, L and H, respectively). Main effects of antibiotic administration were not significant. Increases in DM intake when SBM was given were large compared with the small elevations in ruminal digestion, implying that metabolic regulation was modifying intake of low-quality forage.     

Post-weaning changes in the digestive physiology and caecal fermentative activity in the greater cane rat (Thryonomys swinderianus)

The greater cane rat is a recently domesticated monogastric herbivore, and the importance of the caecum in the functioning of its digestive tract has frequently been mentioned. However, no data are available on caecal fermentative activity of this animal and research on the digestive physiology was only performed in adult animals. The present work was initiated to describe some parameters of the digestive tract anatomy and to study caecal fermentation of the growing cane rat. Thirty 40-day-old weaned cane rats were used in this experiment. Six of them were immediately euthanased and 12 were housed in a collective pen for gastrointestinal tract (GIT) parameters measurements. Twelve others were kept in individual cages to record growth and food intake. Captive cane rats received a pelleted diet containing 12.5% of crude protein and 16.7% of lignocellulose. Six of the 12 collectively housed animals were euthanased on day 82 and a further six on day 103. The growth rate increased with age (P < 0.01) with a linear growth curve (P < 0.001) while the feed intake (g/kg body weight) did not vary (P > 0.05). The caecum represented the largest compartment of the digestive tract constituting more than 40% of total GIT contents. Acetate was the most abundant short-chain fatty acid with more than 70% of the total, followed by propionate (less than 25%) and butyrate (around 5%). Short-chain fatty acid profiles varied with age: when age increased, the acetate proportion increased (P < 0.01), the propionate proportion decreased (P < 0.001) and the butyrate proportion remained unchanged (P > 0.05). The propionate/butyrate ratio showed a decrease with an increase in age (P = 0.05). Ammonia concentrations did not vary with age (P > 0.05). It is concluded that the caecum is an important site of fermentation in the growing cane rat.     

Glutamate dehydrogenase and glutamine synthetase activity in the digestive tract in lambs in relation to age]

Developmental dynamics was investigated in the activity of glutamate dehydrogenase (GDH, E.C. 1.4.1.2.-4) and glutamine synthetase (GS, E.C. 6.3.1.2) in different parts of the digestive tract of lambs, in dependence on the age from 10 to 90 days; the goal of these investigations was to elucidate in greater detail the role of the above enzymes in nitrogen metabolism. The activity of GDH, and of the coenzymes NADH and NADPH, was followed in the digesta because simple organisms (bacteria, fungi, plants) have two glutamate dehydrogenases: they differ from each other by coenzyme specificity, unlike GDH from animal sources which can utilize both NADH coenzyme and NADPH coenzyme (Fahien et al., 1965; Frieden, 1964). The following activities of GDH and GS were found out in trials with lambs at the age of 10, 20, 30, 40 and 90 days, as to the different parts of digestive tract: in the tissues of rumen, omasum, reticulum, spleen, duodenum, jejunum, ileum, int. caecum and colon the activity of GDH (NADH) varied from 0.031 to 0.305 nkat/mg dry matter, in the digesta from 0 to 2.92 nkat/mg dry matter. An investigation of GDH (NADH, NADPH) dynamics in the digesta of lambs showed the relatively high activity of GDH (NADH) in the digesta of colon at the age of 10 days and that of GDH (NADPH) in the digesta of int. caecum. The activity of GDH (NADH) was also found to be high in the digesta of int. caecum at the age of 20 days. In that period the activity of GDH (NADH, NADPH) in the digesta of rumen, omasum and reticulum was zero.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of maize starch concentration in the diet on starch and cell wall digestion in the dairy cow

An in vivo experiment was performed to determine the effect of level of maize starch in the diet on digestion and site of digestion of organic matter, starch and neutral detergent fibre (NDF). In a repeated change‐over design experiment, three cows fitted with a rumen cannula and T‐piece cannulae in duodenum and ileum received a low‐starch (12% of ration dry matter) and a high‐starch (33% of ration dry matter) diet. Starch level was increased by exchanging dried sugar beet pulp by ground maize. After a 2‐week adaptation period, feed intake, rumen fermentation parameters (in vivo and in situ), intestinal flows, faecal excretion of organic matter, starch and NDF were estimated. When the high‐starch diet was fed, dry matter intake was higher (19.0 kg/day vs. 17.8 kg/day), and total tract digestibility of organic matter, starch and NDF was lower when the low‐starch diet was fed. Maize starch concentration had no significant effect on rumen pH and volatile fatty acid concentration nor on the site of digestion of organic matter and starch and rate of passage of ytterbium‐labelled forage. On the high‐starch diet, an extra 1.3 kg of maize starch was supplied at the duodenum in relation to the low‐starch diet, but only an extra 0.3 kg of starch was digested in the small intestine. Digestion of NDF was only apparent in the rumen and was lower on the high‐starch diet than on the low‐starch diet, mainly attributed to the reduction in sugar beet pulp in the high‐starch diet. It was concluded that without the correction for the reduction in NDF digestion in the rumen, the extra supply of glucogenic (glucose and propionic acid) and ketogenic nutrients (acetic and butyric acid) by supplemented starch will be overestimated. The mechanisms responsible for these effects need to be addressed in feed evaluation.     

The comparative study digestion and metabolism of nitrogen and purine derivatives in male, Thai, Swamp buffalo and Thai, Brahman cattle

Studies on in vivo digestion, rates of passages, metabolism of nitrogen, urinary purine derivative excretion and blood metabolites were carried out in Thai Brahman cattle and Thai swamp buffaloes (16 months old). The animals were fed mixed diets based on pineapple (Ananas comusus) waste silage containing urea‐N (NPN) and true protein from a concentrate (TP). The Brahman cattle (310 ± 15 kg) were heavier than the swamp buffaloes (195 ± 9.4 kg) and had higher dry matter (DM), organic matter (OM) and neutral detergent fiber (NDF) intakes when compared on the basis of their metabolic body weight (BW^0.75), but these intakes did not differ significantly when the diets of each animal species were compared. The total tract, apparent digestibilities of dry matter (DM) and organic matter (OM) were not significantly different between the animal species when comparing the two types of diets. The NDF digestibility was significantly (P < 0.01) decreased in both animal species when fed the TP diet, but was significantly (P < 0.01) greater in cattle than in swamp buffaloes. The passage rate digesta k₁ (P < 0.01) and the passage rate digesta k₂ (through the caecum and proximal colon) (P < 0.03) were significantly slower, and the total mean retention time (TMRT) (P < 0.01) was significantly longer in swamp buffaloes when compared to Brahman cattle, but the transit time (TT) showed no difference (P = 0.07) between the animal species or the diets. The N intakes were not different in both animal species and diets, but urine‐N was greater (P < 0.05) in Brahman cattle than that in swamp buffaloes. Urine N and digestibility of N were significantly (P < 0.04) higher in animals fed the NPN diet than those fed the TP diet. Urinary purine derivatives (PD) and the creatinine (Cr) excretion of swamp buffaloes were significantly (P < 0.01) lower than those in Brahman cattle. Plasma urea‐N (BUN) concentration was significantly (P < 0.01) higher in swamp buffaloes than that in Brahman cattle, but plasma glucose and insulin concentrations were significantly (P < 0.01) higher in Brahman cattle than in swamp buffaloes. The concentrations of non‐esterified fatty acids (NEFA) were not significantly (P > 0.05) different in animals fed different diets. The present study demonstrated that Brahman cattle were better in fiber digestibility than swamp buffaloes at utilizing pineapple waste silage with both N sources.     

Diet type affects viscosity of ileal digesta of dogs and simulated gastric and small intestinal digesta

Two experiments were conducted to determine effects of diet type on viscosity of ileal digesta of dogs and simulated gastric and small intestinal digesta. In experiment 1, three canned and three dry dog foods were surveyed for effects on ileal digesta viscosity. Experiment 2 evaluated the same six diets for effects on simulated gastric and small intestinal digesta. Canned diets and dry diets contained an average 22.7% and 89.9% dry matter (DM) respectively. Concentrations of total dietary fibre (TDF) in the diets ranged from 1.8% to 26.5%. Ileal digesta viscosities ranged from 1326 to 46,641 and 7748 to 10,208 cP for canned and dry treatments respectively. Ileal DM concentrations ranged from 8.2% to 16.2% and 15.4% to 15.8% for canned and dry treatments respectively. Dry matter intake ranged from 224 to 290 and 295 to 325 g/day for canned and dry treatments respectively. During gastric digestion simulation, viscosity peaked at 2 and 4 h for all three canned diets and dry diets respectively. During small intestinal digestion simulation, viscosity peaked between 6 and 12 h for most diets except one canned diet and one dry diet, which contained high concentrations of TDF (25.1% and 26.5% respectively). Viscosity of these solutions peaked between 12 and 18 h. Viscosity of ileal digesta and simulated gastric and small intestinal digesta was the lowest after consumption of canned diets with the exception of the canned diet containing very high concentrations of dietary fibre (25.1% TDF). Ileal digesta viscosity of dogs appears to be responsive to the diet type characteristics.     

Fragmentation and ruminal escape of particles as related to variations in voluntary intake, chewing behavior and extent of digestion of potentially digestible NDF in heifers

The distribution of particles of differing sizes in ruminal, duodenal and fecal samples, the efficiency of particle breakdown and ruminal escape and their relationships to voluntary intake, chewing behavior and extent of digestion of potentially digestible NDF were examined in six heifers (290 kg average BW) with ruminal, duodenal and ileal cannulas. Animals had ad libitum access to corn silage, with or without 100 mg monensin head-1.d-1, in a two-period crossover design. Variations in voluntary intake by individual animals were positively related to size of digesta particles (median retaining aperture, MRA) in the dorsal rumen (P = .07) and rectum (P = .08), but not to MRA of particulate matter from the ventral rumen and duodenum. No significant relationships existed among eating or ruminating activities and distribution of particles of differing sizes in digesta from any of the digestive sites. The MRA of particulate matter in duodenal and rectal digesta were negatively related (P = .08 and P = .10) to extent of digestion of potentially digestible NDF (PDNDF) at these sites. Voluntary intake was related positively to efficiency of ruminative degradation of digesta particles appearing at the duodenum (P = .09) and to duodenal DM digesta flow per opening of the reticulo-omasal orifice (ROO; P = .02), the latter being negatively related to extent of digestion of PDNDF in duodenal digesta (P = .09). These results suggest that animals with higher intake capability are more efficient ruminators and can partially override constraining factors of particle size and byoyancy and thereby achieve a larger amount of DM flowing per opening of the ROO.     

Separation and retrograde transport in the large intestine of herbivoresSéparation et transport retrograde dans le gros intestin des herbivoresTrennung und rückwärtiger transport im grimmdarm der pflanzenfresser

Mechanisms leading to the separation of small particles (including microorganisms), water-soluble substances and water from large dry matter particles occur in the large intestine in rabbits, poultry and some small rodents such as the Scandinavian lemming, the chinchilla and the guinea pig. In rabbits water secreted in the proximal colon and absorbed in the caecum together with antiperistaltic movements of the wall of the haustra wash out and transport fine matter back to the caecum, whereas coarse matter continues in the anal direction and is delivered in hard faecal pellets.In some rodents the anatomical arrangements allow a selective delay of microorganisms in the caecum and the most proximal part of the colon.In poultry selective filling of the caeca together with retrograde transport of urine from the cloaca to the caeca allow only fluid and fine matter to pass into the caeca, whereas coarse matter is delivered in the ordinary faeces.Separation and retrograde transport result in both a high average rate of transport of food and food residues through the digestive tract and a relatively high degree of digestibility, allowing these animals to live on food rich in fiber and low in easily digested nutrients.