Invited review: Role of physically effective fiber and estimation of dietary fiber adequacy in high-producing dairy cattle.

Highly fermentable diets require the inclusion of adequate amounts of fiber to reduce the risk of subacute rumen acidosis (SARA). To assess the adequacy of dietary fiber in dairy cattle, the concept of physically effective neutral detergent fiber (peNDF) has received increasing attention because it amalgamates information on both chemical fiber content and particle size (PS) of the feedstuffs. The nutritional effects of dietary PS and peNDF are complex and involve feed intake behavior (absolute intake and sorting behavior), ruminal mat formation, rumination and salivation, and ruminal motility. Other effects include fermentation characteristics, digesta passage, and nutrient intake and absorption. Moreover, peNDF requirements depend on the fermentability of the starch source (i.e., starch type and endosperm structure). To date, the incomplete understanding of these complex interactions has prevented the establishment of peNDF as a routine method to determine dietary fiber adequacy so far. Therefore, this review is intended to analyze the quantitative effects of and interactions among forage PS, peNDF, and diet fermentability with regard to rumen metabolism and prevention of SARA, and aims to give an overview of the latest achievements in the estimation of dietary fiber adequacy in high-producing dairy cattle. Recently developed models that synthesize the effects of both peNDF and fermentable starch on rumen metabolism appear to provide an appropriate basis for estimation of dietary fiber adequacy in high-producing dairy cows. Data suggest that a period lasting more than 5 to 6h/d during which ruminal pH is <5.8 should be avoided to minimize health disturbances due to SARA. The knowledge generated from these modeling approaches recommends that average amounts of 31.2% peNDF inclusive particles >1.18mm (i.e., peNDF(>1.18)) or 18.5% peNDF inclusive particles >8mm (i.e., peNDF(>8)) in the diet (DM basis) are required. However, inclusion of a concentration of peNDF(>8) in the diet beyond 14.9% of diet DM may lower DM intake level. As such, more research is warranted to develop efficient feeding strategies that encourage inclusion of energy-dense diets without the need to increase their content in peNDF above the threshold that leads to lower DM intake. The latter would require strategies that modulate the fermentability characteristics of the diet and promote absorption and metabolic capacity of ruminal epithelia of dairy cows.

Evaluation of the response of ruminal fermentation and activities of nonstarch polysaccharide-degrading enzymes to particle length of corn silage in dairy cows.

The main objective of this study was to evaluate effects of particle length (PL) of corn silage (CS) on distribution of dietary particle fractions, contents of physically effective neutral detergent fiber (peNDF), cows' intake patterns and sorting activity, fermentation pro-file, and activities of nonstarch polysaccharide-degrading enzymes as well as degradation in the rumen and total tract in lactating dairy cows. Four ruminally cannulated Holstein cows, weighing 624 +/- 50 kg and 60 +/- 8 d in milk, were fed ad libitum 3 total mixed rations [about 16% crude protein, 34% neutral detergent fiber (NDF), and 7 MJ of net energy of lactation/kg of dry matter (DM)] containing on DM basis 50% concentrate, 10% grass hay, and 40% CS with 3 different theoretical PL at harvesting (14, 8.1, and 5.5 mm for long, medium, and short, respectively). Results showed that the amount of DM retained on sieves with 19- and 8-mm screens of Penn State Particle Separator decreased linearly with decreasing PL of CS. The latter was reflected in a significant decrease in the content of dietary peNDF including both the DM (peNDF(>8)) and the NDF (peNDF(>8-NDF)) retained on 19- and 8-mm screens. In contrast, the fraction of particles retained between the 1.18- and 8-mm screens was increased, such that no differences among the diets were observed regarding the content of peNDF that includes DM of particles >1.18 mm (peNDF(>1.18)). The intake of particles retained between the 1.18- and 8-mm screens increased linearly, whereas the intake of peNDF(>1.18) increased quadratically with decreasing PL of CS. Sorting consumption was reduced by feeding the short CS, which was reflected in a reduced proportion of propionate and increased acetate-to-propionate ratio and butyrate pro-portion in the rumen. In contrast, no effects of PL of CS were observed on the concentration of total volatile fatty acids and pH in the rumen. In general, decreasing the PL of CS significantly increased the activities of nonstarch polysaccharide-degrading enzymes. However, greater ruminal and total tract degradation of fiber and nonfiber carbohydrates were observed only by medium CS. Results of the present study suggest that in addition to fractions of long particles (i.e., >8 mm), the particle fraction retained between 1.18- and 8-mm should also be considered to better predict rumen conditions and digestion. In conclusion, a moderate reduction of PL of CS has beneficial effects on nutrient digestion, and may maximize feed efficiency and energy supply in high-yielding dairy cows.

Modeling the adequacy of dietary fiber in dairy cows based on the responses of ruminal pH and milk fat production to composition of the diet.

The main objective of this study was to develop practical models to assess and predict the adequacy of dietary fiber in high-yielding dairy cows. We used quantitative methods to analyze relevant research data and critically evaluate and determine the responses of ruminal pH and production performance to different variables including physical, chemical, and starch-degrading characteristics of the diet. Further, extensive data were used to model the magnitude of ruminal pH fluctuations and determine the threshold for the development of subacute ruminal acidosis (SARA). Results of this study showed that to minimize the risk of SARA, the following events should be avoided: 1) a daily mean ruminal pH lower than 6.16, and 2) a time period in which ruminal pH is <5.8 for more than 5.24 h/d. As the content of physically effective neutral detergent fiber (peNDF) or the ratio between peNDF and rumen-degradable starch from grains in the diet increased up to 31.2 +/- 1.6% [dry matter (DM) basis] or 1.45 +/- 0.22, respectively, so did the daily mean ruminal pH, for which a asymptotic plateau was reached at a pH of 6.20 to 6.27. This study also showed that digestibility of fiber in the total tract depends on ruminal pH and outflow rate of digesta from reticulorumen; thereby both variables explained 62% of the variation of fiber digestibility. Feeding diets with peNDF content up to 31.9 +/- 1.97% (DM basis) slightly decreased DM intake and actual milk yield; however, 3.5% fat-corrected milk and milk fat yield were increased, resulting in greater milk energy efficiency. In conclusion, a level of about 30 to 33% peNDF in the diet may be considered generally optimal for minimizing the risk of SARA without impairing important production responses in high-yielding dairy cows. In terms of improvement of the accuracy to assessing dietary fiber adequacy, it is suggested that the content of peNDF required to stabilize ruminal pH and maintain milk fat content without compromising milk energy efficiency can be arranged based on grain or starch sources included in the diet, on feed intake level, and on days in milk of the cows.

Effects of varying dietary forage particle size in two concentrate levels on chewing activity, ruminal mat characteristics, and passage in dairy cows.

The objective of this study was to investigate the effects of varying dietary forage particle size on chewing activity, ruminal mat characteristics, passage, and in situ ruminal and total tract digestion in dairy cows at a low- and high-concentrate inclusion. The experiment was designed as a 4 x 4 Latin square with a 2 x 2 factorial arrangement of treatments. Four ruminally cannulated late-lactating dairy cows were restrictively fed (17 kg of dry matter/d), in four 23-d periods, 1 of 4 different diets varying in the theoretical particle size (6 and 30 mm) of hay (56.6% NDF of dry matter) and in the levels (approximately 20 and 60%, dry matter basis) of a cereal-based concentrate. Ingredients of the ration were offered separately to the cows; dietary hay and low-level concentrate were offered twice daily at 0800 and 1600 h, whereas concentrate of the high-level treatment was offered in 4 meals a day at 0800, 1200, 1600, and 1900 h. This study showed that altering the forage particle size from 6 to 30 mm in a low-concentrate diet significantly increased the rumination time and ruminal mat consistency without affecting ruminal fermentation and passage. Further, particle breakdown and proportion of mat in the rumen increased, and in situ hay dry matter degradability improved, which in turn indicated a higher capacity of ruminal digesta to degrade fiber. On the other hand, increasing the forage particle size in a diet containing a high amount of concentrate increased the proportion of dry matter retained on a 1.18-mm screen from 37.5 to 42.0% and extended the rumination time by 100 min/d, as well as increasing the ruminal mat consistency. However, ruminal particle breakdown, short-term ruminal pH, fibrolytic capacity of the digesta, and proportion of mat in the rumen decreased. This was also reflected in a higher bailable liquid pool, increased fractional passage rate of solid digesta from the reticulorumen, and increased retention time in the hindgut, which in turn indicated a shift of fiber digestion from the rumen to the lower digestive tract. This study showed that the response of chewing or ruminating activity alone seemed to be insufficient to assess the dietary physical effectiveness or fiber adequacy in limit-fed dairy cows when high-concentrate diets were fed separately. Based on the results of this study, we concluded that inclusion of coarsely chopped hay in the high-concentrate diet did not appear to further improve rumen conditions and digestion when the rations were formulated to exceed the fiber requirements in limit-fed dairy cows.

Natural occurrence of Fusarium toxins in soy food marketed in Germany.

A total of 45 samples of soy food including whole beans, roasted soy nuts, flour and flakes, textured soy protein, tofu, proteinisolate including infant formulas and fermented products (soy sauce) were randomly collected in food and health food stores and analysed for Fusarium toxins. A spectrum of 13 trichothecenes of the A-type as well as of the B-type were determined by gas chromatography/mass spectrometry, zearalenone (ZEA), alpha- and beta-zearalenol (alpha- and beta-ZOL) by high performance liquid chromatography (HPLC) with fluorescence and UV-detection. Detection limits ranged between 1 and 19 microg/kg. At least one of the toxins investigated was detected in 11 out of a total of 45 samples of soy food belonging to different commodities. Scirpentriol (SCIRP), 15-monoacetoxyscirpenol, 4,15-diacetoxyscirpenol, T-2 tetraol, HT-2 toxin, deoxynivalenol (DON), 15- and 3-acetyldeoxynivalenol, ZEA, alpha- and beta-ZOL were detected in at least one sample, T-2 triol, T-2, NEO, NIV and FUS-X were not detected in any sample. Five out of 11 samples were positive for one toxin, one sample for two, three, six or seven toxins, two samples for 5 toxins, demonstrating the possibility of a contamination of soy food with a spectrum of Fusarium toxins. SCIRP, DON and ZEA were found up to 108, 260 and 214 microg/kg, the other toxins did not exceed 61 microg/kg. A first insight into the contamination of soy food with a broad spectrum of Fusarium toxins is provided.

Subacute effects of moderate feed loads of isolated Fusarium toxin deoxynivalenol on selected parameters of metabolism in weaned growing piglets.

In 36 female weaned piglets, the effect of different dosages (0, 300, 600 and 1200 microg/kg feed) of isolated, pure Fusarium toxin deoxynivalenol (DON) was examined during a period of 8 weeks. Standardised trial conditions were provided. Pigs were fed restrictively to allow a complete feed intake of all animals. Parameters of liver integrity, haematological data and blood concentrations of some selected metabolic components of energy and protein metabolism were examined weekly. Enzyme aspartate aminotransferase was affected subclinically by age and significantly by dosage, which was proved by Wald F-test. Some additional enzymes, for instance alanine aminotransferase, gamma glutamyl transferase, glutamate dehydrogenase and sorbit dehydrogenase, showed no clear systematic effect. Urea and glucose in the blood were inter-related. Depending on DON load with increasing glucose concentrations, the urea level declined. Albumin and total protein in serum showed no significant DON-related effect. Haemoglobin in blood was found to be significantly affected by DON, which was proved by the Wald F-test, where the effect was more pronounced with 600 microg DON/kg diet compared to 1 200 microg DON/kg. An obvious DON-related affection of liver, N-metabolism and stimulation of haematopoiesis depending on dosage and time is discussed.

Relationship between thiamine concentration and fermentation patterns in the rumen fluid of dairy cows fed with graded concentrate levels.

The objective of this study was to investigate the relationship between the thiamine concentration and the fermentation patterns [pH, concentration of short-chain fatty acids (SCFA)] in the free liquid (FRL) and particle-associated liquid (PARL) of the rumen in dairy cows fed with graded concentrate levels in the diet. Four ruminally cannulated Holstein cows in mid lactation were fed [semi-ad libitum, 18 kg dry matter (DM)/day] diets consisting of hay (H) and slowly degradable concentrate (C), offered in five different H:C ratios (% DM basis) in the following sequence: period 1, 30:70; period 2, 40:60; period 3, 50:50; period 4, 60:40 and period 5, 75:25. A negative quadratic relationship was observed between thiamine concentration in FRL and intake of dietary thiamine (R(2) = 0.36), of concentrate (R(2) = 0.38) and of digestible non-fibre carbohydrates (R(2) = 0.37). The thiamine concentration in PARL was higher (p < or = 0.05) compared to FRL. The ruminal thiamine concentration correlated negatively to pH and positively to concentrations of SCFA and propionate in the rumen. R(2) of these relationships varied markedly (0.002 and 0.77), depending on time after feeding and fluid digesta compartment. The higher R(2) were observed at 8 and 11 h after the morning feeding for FRL (R(2) 0.46-0.71) and PARL (R(2) 0.41-0.77), respectively.

Effects of physically effective fiber on digestive processes and milk fat content in early lactating dairy cows fed total mixed rations.

Data from recent research studies were analyzed quantitatively, and the random effect of experiment was assessed to define the physiological responses of dairy cows in early lactation to intake of physically effective neutral detergent fiber (peNDF). All studies were conducted with lactating Holstein cows (84.8 +/- 3.54 days in milk) in Latin square designs, and feeds were offered ad libitum as total mixed rations (TMR). The peNDF was estimated by 2 measurement techniques, the NDF content of TMR multiplied by amount of dry matter (DM) retained on a 1.18-mm screen (peNDF(> 1.18)) and NDF content of TMR multiplied by the proportion of DM retained by 19- and 8-mm Penn State Particle Separator screens (peNDF(> 8)). Other factors, including concentrations of NDF, forage NDF, non-fiber carbohydrates, the amount of digestible organic matter of forages (FDOM), and the intake of ruminally degradable starch (RDSI) from grain in the diet were also investigated. The studied animal response variables included feed intake, ruminal fermentation, chewing activity, fiber digestibility, and milk production and composition. The ruminal pH (day mean) in this study ranged from 5.30 to 6.59. Using peNDF(> 1.18) approach, the requirements for physically effective fiber in high-yielding dairy cows fed TMR in an ad libitum intake were estimated to be about 19% of ration DM or 4.1 kg/d or 0.6 kg/100 kg of body weight to maintain a ruminal pH of about 6.0. When peNDF was measured as peNDF(> 8), ruminal pH responded in a quadratic fashion but the confidence of estimation was lower (R(2) = 0.27) compared with the peNDF(> 1.18) approach (R(2) = 0.67). Results of these data analyses showed that peNDF(> 1.18) provided a satisfactory estimation of the mean ruminal pH (R(2) = 0.67) and NDF digestibility (R(2) = 0.56). Furthermore, peNDF(> 1.18) was poorly, although positively, correlated to daily chewing (R(2) = 0.17), and rumination (R(2) = 0.24) activity. On the other hand, results from these analyses showed that milk parameters are less sensitive to the effects of dietary peNDF than other variables, such as ruminal pH, chewing activity, and fiber digestibility. Dietary FDOM correlated positively (moderately) to ruminal pH (R(2) = 0.24), daily chewing (R(2) = 0.23), and rumination (R(2) = 0.29) activity, whereas the daily RDSI from grain correlated negatively to ruminal pH (R(2) = 0.55) and positively to total volatile fatty acids (R(2) = 0.27). Inclusion of FDOM and RDSI from grain along with peNDF(> 1.18) in the models that predict rumen pH further improved the accuracy of prediction. This approach appeared to further complement the concept of peNDF that does not account for differences in ruminal fermentability of feeds.

Mycotoxins in food systems in Sub Saharan Africa: A review.

Mycotoxins, toxic secondary metabolites of fungi are now recognised as major cause of food intoxications in Sub Saharan Africa (SSA). Aflatoxins, the most important of the group have been implicated in acute aflatoxicoses, carcinogenicity, growth retardation, neonatal jaundice and immunological suppression in SSA. The hot and humid tropical climate provides ideal condition for growth of toxigenicAspergillus spp, making food contamination to be widespread in SSA, with maize and groundnuts being the most contaminated. The available data suggests that cassava products (the most important African food) are not prone to aflatoxin contamination. Recent data on ochratoxin A produced by species ofAspergillus on grains have indicated the necessity for it to be monitored in SSA. Fumonisins represent the most importantFusarium mycotoxins in SSA, and surveillance data indicate very high contamination rates of almost 100% in maize samples from West Africa. Limited information exists on the occurrence of trichothecenes, while the data currently available suggest that zearalenone contamination seems not to be a problem in SSA. The strategies under investigation to mitigate the mycotoxin problem in SSA include education of the people on the danger of consuming mouldy foods, pre and post harvest management strategies with emphasis on biological control, use of plant products to arrest fungal growth during storage, enterosorbent clay technology, and the search for traditional techniques that could reduce/detoxify mycotoxins during food processing.

Fusarium toxin contents of maize and maize products purchased in the years 2000 and 2001 in Germany.

Samples (n=106) of maize and maize products were analysed for 13 trichothecene toxins and zearalenone (ZON). All 14 toxins examined were detected, although with varying frequency. Cooccurrence of two or more toxins was observed in 96% of samples. The toxins of the scirpenol group scirpentriol, 15-monoacetoxyscirpenol and diacetoxyscirpenol were detected in 14, 27 and 3% of the samples analysed, the toxins of the T-2 group T-2 toxin, HT-2 toxin, T-2 triol und T-2 tetraol were found in 33, 66, 2 and 7%. Toxin content was higher in feeds than in foods (semolina and flour). In food samples, the German regulatory level for DON (500 µg/kg) was not exceeded, three samples of maize flour contained ZON above the regulatory level (50 µg/kg).

Investigation on the "In vitro" degradation of zearalenone in rumen fluid.

Ruminal zearalenone (ZEA) degradation in "in vitro" digestion was examined in different variants using the Hohenheimer Gas Test. First, the mycotoxin degradation was measured using squeezed rumen fluid from solid digesta of the dorsal sack and free rumen fluid from the ventral sack, respectively. Then free rumen, fluid of the ventral sac was used with addition of concentrate and mixtures of concentrate with sun-flower oil and starch, respectively. Within 24 hours ZEA was degraded down to 63% and 49% of the initial concentration when incubated with solid and fluid rumen digesta, respectively. Using additives and rumen fluid concentrate for incubation, concentrate, concentrate with oil and concentrate with starch, respectively, a reduction of ZEA to 46, 56 and 37% of the initial toxin concentration was observed.

Intake estimates for trichothecene toxins of the population in Southwest Germany in 1998 and in 1999.

The intake of theFusarium toxins deoxynivalenol (DON), nivalenol (NIV), HT-2 and T-2 toxin (HT-2, T-2), 3-, 15-acetyldeoxynivalenol (3-, 15- ADON), and fusarenon-X (FUS-X) was calculated for adults, children and babies, for an area of southwest Germany and two years (1998, 1999). Estimates were based on consumption data of bread and pasta by both adults and children and of infant food by babies, reported for the German population in a study on behalf of the European Union, and on toxin contents of a total of 208 samples of these commodities. No exceeding of the tolerable daily intake (TDI) of DON, NIV and the sum of HT-2 and T-2, as stated by the EU, was found for adults (70 kg body weight (BW)) and for babies (10 kg BW), independent of year and level of consumption. For children (20 kg BW) the intake of DON exceeded the TDI in 1998 for high, and in 1999 for both mean and high consumers. For both years the intake of the sum of HT-2 and T-2 was below the TDI following mean but above this value following high consumption. The intake of NIV was far below the TDI for both levels of ingestion. The daily intake of each of the three toxins 3-, 15- ADON and FUS-X was below 0.03, 0.11 and 0.05 µg/kg/BW for adults, children and babies, respectively.

Survey of Fusarium toxins in foodstuffs of plant origin marketed in Germany.

A total of 219 samples of foodstuffs of plant origin, consisting of grain-based food, pseudocereals and gluten-free food as well as vegetables, fruits, oilseeds and nuts, were randomly collected during 2000 and 2001 in food and health food stores. A spectra of 13 trichothecene toxins including diacetoxyscirpenol (DAS), 15-monoacetoxyscirpenol (MAS), scirpentriol (SCIRP), T-2 and HT-2 toxins (T-2, HT-2), T-2 triol, T-2 tetraol, neosolaniol (NEO) of the A-type as well as deoxynivalenol (DON), 3- and 15-acetyl-DON (3-, 15-ADON), nivalenol (NIV), and fusarenon-X (FUS-X) of the B-type were determined by gas chromatography/mass spectrometry. Analysis of zearalenone (ZEA), alpha- and beta-zearalenol (alpha- and beta-ZOL) was made by high-performance liquid chromatography with fluorescence and UV-detection. Detection limits ranged between 1 and 19 microg/kg. Out of 84 samples of cereal-based including gluten-free foods, 60 samples were positive for at least one of the toxins DON, 15-ADON, 3-ADON, NIV, T-2, HT-2, T-2 tetraol and ZEA, with incidences at 57%, 13%, 1%, 10%, 12%, 37%, 4% and 38%, respectively, whereas SCIRP and its derivatives MAS and DAS, T-2 triol, Fus-X as well as alpha- and beta-ZOL were not detected in any sample of this subgroup. Contents of DON ranged between 8 and 389 microg/kg, for all other toxins determined concentrations were below 100 microg/kg. The pseudocereals amaranth, quinoa and buckwheat were free of the toxins investigated. Ten of 85 samples of vegetables and fruits were toxin positive. ZEA and the type A trichothecenes MAS, SCIRP, DAS, HT-2 were detected in 7, 3, 2, 1 and 1 samples, respectively. Out of 35 samples of oilseeds and nuts, 7 samples were toxin positive. HT-2, T-2 and ZEA were detected in 4, 3 and 4 samples, respectively. In vegetables and fruits as well as in oilseeds and nuts, toxin levels were below 50 microg/kg. None of the B-type trichothecenes analysed was found for both subgroups.

Pectin in pig nutrition, a comparative review.

A comprehensive review is given on pectin effects in pigs. Its effects on feed passage and digestion in the small intestine, the composition of ileal digesta and fermentation in the colon are described. Pectins promote fermentation at the terminal ileum and in the first part of the colon. It is shown, that pectin opposite to cellulose is degraded to high extents in the colon. Dietetic effects in relation to composition of ileocaecal digesta, endogenous secretions, buffering and pH-stability, high fermentability of organic matter in the colon and resulting volatile fatty acids (VFA) in the cranial part of the colon and even its possible interactions to colonization of the gut by infectious bacteria are described. Pectin effects concerning volume of the intestinal tract, distribution of VFA and lactic acid, role of endogenous secretions are described. The negative effect of pectins on praecaecal digestibility, their high degradation rates in the large intestine and consequences for their dietetic effects are discussed.

Digesta characteristics of dorsal, middle and ventral rumen of cows fed with different hay qualities and concentrate levels.

The influence of fibre content of hay (H) and concentrate level (C) on local differences in the composition of ruminal digesta (ratio of solid to fluid digesta, DM, NDF, ADF and ADL content), particle size (MPL), specific gravity (SG) and fermentation (pH and concentrations of SCFA and bicarbonate) have been tested on two ruminally cannulated Friesian cows (520 kg BW) which were fed restricted, using individual cows as experimental units. Digesta samples were collected via cannula from three rumen layers: 5 to 10 cm (top) and 25-35 cm beneath the top of the particle mat (middle) and 5-10 cm above the rumen floor (bottom). For a main plot treatment (H x C), repeated samples were collected at four time intervals (1 h before and 2, 5 and 10 h after morning feeding) on each of two days. From top to bottom rumen the share of solid digesta mass (SM), DM and NDF contents of squeezed digesta fluid (SRF) and concentration of SCFA decreased (P < 0.05); pH and bicarbonate concentration increased (P < 0.05), while DM, NDF, ADF and ADL contents in SM, MPL and SG did not differ. Higher NDF content of hay (from 47-62%) increased SM, fibre fractions in SM, MPL, pH and concentration of bicarbonate in ruminal digesta, especially when 50% concentrate was given, while SG decreased. When the concentrate level was enhanced from 20 to 50%, digesta SM, MPL and the content of DM and NDF in SRF increased, while pH, concentrations of SCFA and acetate decreased when low-fibre hay was given. With longer time after feeding the digesta SM was reduced and fibre content in SM increased. The increase of the fibre content of hay reduced the possible negative effect of high concentrate level on the stratification of ruminal digesta. The decrease of the fibre content of hay promised better conditions for fibre digestion in the rumen when concentrate availability is limited.

The influence of 5% and 10% dietary apple pectin on parameters of fermentation in faeces and caecal digesta of weaning pigs.

In order to determine the effect of pectin on fermentation parameters in the faeces and caecal digesta of weaned pigs 18 castrated male crossbred pigs with an average body weight of 8 kg were fitted with T-cannulas at the caecum. The animals were randomly distributed into three groups and fed with diets supplemented with 0, 5 and 10% pectin. Faeces were collected over a period of 3 days. Thereafter the diets were withdrawn for 24 h followed by ad libitum feeding to enhance the feed intake. Caecal chyme was collected 0, 8 and 24 h postprandial. In the faeces the addition of 5% pectin to the diet lowered the content of dry matter and lactic acid. The pH and the digestibility of pectins, the concentration of total SCFA, acetate, propionate, butyrate, bicarbonate and chloride increased. Dietary pectin of 10% increased the content of total SCFA and acetate further. When the diets were withdrawn and fed ad libitum 24 h later, a decline of the pH and an increased concentration of lactate in the caecal chyme could be observed in all groups up to 8 h after feeding. With an interval of 8 to 24 h after feeding, a further decline in pH and a rise of lactate only occurred when the diet was not supplemented with pectin. It was concluded that pectin might be beneficial for the development of fermentative processes in the large intestine.

Energy requirements of cattle for standing and for ingestion, estimated by a ruminal emptying technique.

Energy requirements for ingestion and standing were determined in open-circuit respiration chambers with four ruminally cannulated German Red Pied steers weighing 617 +/- 53 kg of BW (mean +/- SD). The requirement for standing over lying was derived by regressing heat production on time spent standing within 2-h periods when no feed was offered to avoid any interference with eating activity, and amounted to 14 kJ/(d x kg of BW). The energy requirement for ingestion was determined by calculating the difference between heat production during a 2-h period without feed and during a consecutive 2-h period in which straw of different particle sizes, fresh and conserved grass, or rolled barley were offered for ad libitum intake. Before measurements, the rumens of the steers were emptied, washed, and filled with a buffer solution to avoid heat production by metabolism of absorbed nutrients from the feed ingested during the experimental periods. The mean value for all feeds tested was 20 J/(min of ingestion x kg BW). Relating heat production to the amount of DM or fiber ingested did not decrease variation among feeds. This confirms the observations of earlier studies, that energy requirement for ingestion is mainly determined by time spent eating. Results of additional measurements, in which the same amounts of the respective feeds ingested in preceding periods were put into the emptied rumens via the cannulas, showed that the presence of the feed in the rumen did not increase heat production, indicating that the increment of heat production during eating is mainly caused by ingesting and chewing the feed. Further measurements in the same animals with an ingesta-filled rumen showed that ingestion of straw led to an increase in heat production per minute of chewing similar to those with emptied rumens, which confirms the validity of the experimental procedure using ruminally emptied animals to determine the energy requirement for ingestion.

Occurrence of fungi with mycotoxic potential in grain of transylvania and potential hazardous effects in broiler chicken.

Investigations on the mycological quality of feeds from Transylvanian farms are presented. The investigations had two objectives: 1. survey for mycological contamination and related chemical composition; 2. the evaluation of effects ofFusarium graminearum Schw. infested wheat (8% in the diet) on productivity and digestibility of nutrients in broilers. More than 50% of the samples showed water contents exceeding 16%, due to inadequate harvesting and storage conditions. This correlated with high my-cological contamination, with dominant species of the genusFusarium, Aspergillus, Alternaria,Penicillium andRhizopus. Feeding trials with broilers showed that live weight gain and digestibility coefficients of protein and fat in animals givenFusarium infested grain were depressed. As well N-retention and feed conversion rate (kg feeding stuff/ kg weight gain) were impaired.

Deoxynivalenol contents in foodstuffs of organical and conventional production.

Samples of wheat flour, bread, noodles, rice, corn and corn based foods as well as oats and oats based foods of conventional and organical production were analysed for trichothecene toxins. In wheat flour, bread and noodels the median deoxynivalenol (DON) contents were lower in ecological than in conventional products with significant differences for what flour and bread. To estimate toxin uptake of the consumer a corrected mean of DON concentration was calculated, which was lower in wheat flour and bread for ecological than for conventional products. In noodles the corrected mean of organical products was higher than that of conventional ones.

Zeralenone and ergosterol contents in corn samples of Transylvania, Romania.

70 corn samples for feed use out of the harvests of the years 2001 and 2002 were collected randomly in Transylvania, Romania and analysed for zearalenone and for ergosterol as fungal mass indicator. High ergosterol contents were found in some samples with a maximum value of 72 mg/kg, zearalenone contents showed values between 4 and 2250 µg/kg in samples positive, indicating a rather high degree of fungal contamination as well as a serious zearalenone contamination.