Effects of fumaric acid on rumen fermentation, milk composition and metabolic parameters in lactating cows.

The aim of this study was to determine the influence of fumaric acid (FA) on ruminal fermentation and its effects on the acid-base balance of seven ruminally and duodenally fistulated multiparous German Holstein cows. The experiment was conducted in a change-over design with three periods in which the animals were randomly arranged in one of three treatments: Control (C; without FA), 300 or 600 g FA per day. The diets consisted of 7.4 kg DM grass silage, 4.2 kg concentrate mixture and 0, 300 or 600 g FA or wheat starch as isocaloric compensation per day and cow. FA supplementation decreased the rumen pH, acetic acid and butyric acid and increased propionic acid in rumen fluid. The results of the single-strand conformation polymorphism analysis (SSCP) did not show an influence of FA on the microbial population in the rumen. The beta-hydroxybutyrate (BHB) concentration in blood and the pH of the urine decreased, while the blood gases were unaffected by supplementation of the acid. The microbial protein per MJ ME decreased in the duodenum with FA supplementation. The milk fat concentration decreased after addition of FA. We conclude that in this study feeding of up to 600 g FA per day did not result in an acidosis. It seems that up to 600 g FA per day did not have a significant influence on the acid-base balance of dairy cows.

Effect of conjugated linoleic acid supplementation on body composition, body fat mobilization, protein accretion, and energy utilization in early lactation dairy cows.

The objective of the study was to investigate the effects of trans-10,cis-12 and cis-9,trans-11 conjugated linoleic acid (CLA) supplementation on body composition, mobilization or accretion of body fat and protein mass, as well as the energy metabolism of dairy cows during the first 105 d in milk (DIM). For this purpose, a comparative slaughter experiment was conducted with 25 primiparous German Holstein cows. The experiment started at 1 DIM with the slaughter of 5 animals of an initial group receiving no CLA supplement. The remaining animals were fed a CLA supplement (n=10) or a stearic acid-based control fat supplement (CON; n=10) from 1 DIM up to slaughter. After 42 DIM, 5 more cows from each treatment (42-CLA and 42-CON) were slaughtered. The remaining 5 cows in each treatment were slaughtered after 105 DIM (105-CLA and 105-CON). The animals of the CLA groups consumed 6.0 g/d of trans-10,cis-12 CLA and 5.7 g/d of cis-9,trans-11 CLA. During the slaughter process, the empty body mass was recorded and partitioned into 9 fractions (meat, bone, offal, hide, mammary gland, retroperitoneal fat, omental fat, mesenteric fat, and s.c. fat). The fractions were analyzed for dry matter, ether extract, crude protein, and ash to calculate the body composition of the empty body mass at the different slaughter times. The principle of the comparative slaughter technique was applied to estimate body fat or protein mobilization and accretion in the viewed periods from 1 DIM until 42 and 105 DIM. The heat production (HP) was calculated by subtracting the energy in milk and energy changes in body mass from the metabolizable energy intake. The body composition was not affected by CLA supplementation. However, the mobilization of body fat mass from 1 until 42 DIM was 24.1 kg in the 42-CON group and 14.3 kg in the 42-CLA group. This resulted in a trend to lower body mass (fat and protein) mobilization of 10.5 kg in the 42-CLA group. Energy mobilization from body mass was 21.2 MJ/d in the 42-CON and 11.5 MJ/d in the 42-CLA group. The HP was unchanged for the 42-CON and 42-CLA group with 123.0 and 116.9 MJ/d, respectively. From 1 until 105 DIM, the protein accretion was 4.3 kg and the daily energy retention in body protein was 1.0 MJ higher for CLA-supplemented cows. The HP was decreased in this period for the 105-CLA group (115.5 MJ/d) as compared with the 105-CON group (125.9 MJ/d). Overall, the trend for a decreased body mass mobilization suggested a protective effect of CLA supplementation against excessive use of body reserves within 42 DIM. Continuous CLA supplementation until 105 DIM increased protein accretion. The effects on body mass mobilization and protein accretion in combination with the decreased HP in the CLA-fed cows suggested a more efficient utilization of metabolizable energy in CLA-supplemented early lactation dairy cows.

Effect of trans-10, cis-12 conjugated linoleic acid on performance, adipose depot weights, and liver weight in early-lactation dairy cows.

In feeding practice, conjugated linoleic acid (CLA) supplements are used to decrease milk fat excretion in early-lactation dairy cows to save energy to counteract the physiological negative energy balance. The present study was conducted to examine the effects of CLA on energy metabolism, changes in liver weight, and the weight of different adipose depots during early lactation. Primiparous lactating German Holstein cows (n=25) were divided into 5 groups and each group contained 5 animals. The experiment started 21 d prepartum and continued until 105 d in milk (DIM). Cows were slaughtered at 1, 42, and 105 DIM. The experiment was divided into a prepartum period (21 d prepartum until calving), period 1 (1 until 42 DIM), and period 2 (>42 until 105 DIM). In the prepartum period, all animals were housed together and fed the same diet with no CLA supplementation. At 1 DIM, an initial group, with no CLA supplementation, was slaughtered. The 20 remaining cows were assigned to 2 diets. One group received 100g/d of a control fat supplement (CON; n=10) and the other group 100g/d of a CLA supplement (CLA; n=10) from 1 DIM until slaughter. Five cows of each feeding group were slaughtered after 42 DIM and the remaining animals after 105 DIM. The CLA supplement contained approximately 10% each of trans-10, cis-12 CLA and cis-9, trans-11 CLA. During the slaughter process the empty body weight was recorded and the omental, mesenteric, retroperitoneal, and s.c. adipose depots, as well as the liver, were dissected and weighed. The CLA treatment decreased milk fat content in period 1 (14.1%). In period 2, milk fat content (25.4%) and yield (17.1%) were lower in the CLA group. No effect of CLA on milk yield was observed. The net energy intake, milk energy output, and the calculated energy balance remained unchanged by CLA supplementation. No effect of CLA on the weights of liver, omental, mesenteric, or s.c. adipose depots was observed when related to empty body weight. Liver weight increased with DIM, whereas the retroperitoneal adipose depot weight decreased at the same time. Compared with the initial group, the retroperitoneal adipose depot weight for control animals slaughtered after 42 DIM was decreased (47.7%); however, for the CLA group slaughtered after 42 DIM, a trend to a lower retroperitoneal adipose depot weight (34.0%) was observed. This suggests a CLA-induced deceleration of mobilization of the retroperitoneal adipose depot during the first 42 DIM.

The effect of various iodine supplementations and two different iodine sources on performance and iodine concentrations in different tissues of broilers.

1. The objective of this study was to determine the influence of iodine (I) supplementation of feed, within the range of the European guidelines, on the performance of broiler chickens and I transfer into different organs and tissues, especially meat. The main emphasis was to assess whether broiler meat could be enriched and used as an I source in human nutrition. 2. Two experiments were performed, one with KI and the other with Ca(IO(3))(2). For each experiment, 288 d-old broiler chicks were divided into 4 groups (72 birds/group) and fed on diets with supplementations between 0 and 5 mg I/kg feed. The birds were reared to 35 d of age under standard conditions. Six birds per group were slaughtered at 35 d and samples of blood, thyroid gland, liver, pectoral and thigh meat taken. 3. Iodine treatment did not significantly affect the growth and slaughter performance of the broiler chickens. In all investigated parameters, I concentrations increased significantly with increasing I intake of the animals. The lowest I concentrations were measured in the meat, but they were considerably higher in blood serum, liver and thyroid gland. Since the I content of meat was still low in the highest supplemented group (highest median concentration: 67·8 µg I/kg thigh meat), there is no evidence that this could substantially improve I supply in human nutrition.

Pantothenic acid in ruminant nutrition: a review.

Pantothenic acid (PA) is essential in metabolism due to its incorporation into coenzyme A and acyl-carrier-protein. In addition to fodder, ruminants have another PA source, as the micro-organisms in the rumen can synthesize PA. However, it has not been evaluated whether synthesis can meet the PA requirements of dairy cows. Furthermore, synthesis appears to be influenced by forage to concentrate ratio in the diet. It is not yet clear, if oral PA supplementations can increase the duodenal PA flow in dairy cows, but it has been reported that about 80% of supplemented PA disappears between the mouth and duodenum. However, supplementation of PA can increase blood PA levels. To give a general view of the actual state of research, the present review discusses the current knowledge, identifies gaps in knowledge and presents areas for future research.

Effects of a pantothenic acid supplementation to different rations on ruminal fermentation, nutrient flow at the duodenum, and on blood and milk variables of dairy cows.

To investigate the effects of a dietary pantothenic acid (PA) supplementation on duodenal nutrient flows, blood and milk variables and especially on duodenal PA flows and PA concentrations in blood and milk German Holstein cows, equipped with cannulas in the dorsal sac of the rumen and in the proximal duodenum were used. In the first experiment of the study two dry and six lactating cows received a diet with a forage to concentrate (F:C) ratio of 34:66 (high concentrate, HC), whereas in the second experiment a diet with a F:C ratio of 66:34 (high forage, HF) was fed to four dry and five lactating cows. The cows received both rations with or without 1 g PA/day. By supplementing PA to the HC ration, the molar percentage of acetic acid increased, whereas the concentration of total short chain fatty acids, the efficiency of microbial protein synthesis in the rumen and the serum glucose levels, decreased. With the HF ration the PA decreased the molar percentage of propionic acid and increased the amount of ruminally fermented organic matter. Furthermore, PA supplementation only increased the duodenal PA flow with the HF ration, while the serum and milk PA concentrations and milk PA yields were not affected. Based on the results of the present study, a rumen-unprotected supplementation of PA makes no sense.

Variability of mammary blood flow in lactating Holstein-Friesian cows during the first twelve weeks of lactation.

The goals of the present study were to measure mammary blood flow volume (BFV) during the first 12 wk of lactation in dairy cows by using color Doppler sonography and to determine what affects the mammary blood flow. Forty cows were examined via color Doppler sonography on d 1, 7, 14, 28, 56, and 84 after parturition (d 0). The total BFV (BFV(total)) to the 4 mammary glands was calculated by measuring time-averaged maximum velocities (TAMV) and cross-sectional areas (A) of the left and right pudendoepigastric trunks via transrectal color Doppler sonography. Because there were no significant differences in A, TAMV, and BFV between the right and left pudendoepigastric trunks, the means of A and TAMV, and the BFV(total) of both trunks were used for calculations. The intraindividual and interindividual variability of repeated BFV measures quantified by intraclass correlation coefficients were 96 and 98%, respectively. The BFV(total) ranged from 19.9 to 27.9 L/min, with a mean of 22.3+/-4.9 L/min. Interindividual differences in BFV values were attributable to variations in A and TAMV. The interindividual variability of the BFV(total), which was determined using the coefficients of variation of the BFV(total) on individual days, ranged from 16 to 28%. All the cows had similar changes in the BFV(total) during the study. Changes in BFV(total) were not correlated with changes in the mean of A, but there was a good correlation between changes in BFV(total) and in the mean of TAMV (r=0.94). The BFV(total) was highest on d 1 of lactation, decreased 28% by d 7, and remained at this level until d 28. By d 56, the BFV(total) had increased by 15% compared with d 14 and by 10% compared with d 28. The BFV(total) on d 84 was significantly different from all other days except d 56. There were moderate correlations between daily milk yield and BFV on individual days (0.24

Inter- and intra-individual differences in serum copper and zinc concentrations after feeding different amounts of copper and zinc over two lactations.

The influence of different copper and zinc contents in rations on blood serum concentrations was tested in a feeding trial at the Institute of Animal Nutrition of the Federal Research Institute for Animal Health (FLI). A total of 60 German Holstein breed cows (38 first lactating and 22 second lactating cows) were tested. All animals received a diet based on maize- and grass silage ad libitum. The animals were divided into two groups with 30 cows each. Group A received concentrates supplemented with copper and zinc as recommended, whereas Group B was offered a concentrate with roughly double the amount of copper and zinc. Blood samples were taken several times during the lactation. The concentrations of copper and zinc in the serum were measured and correlations between trace element intake and their serum concentrations were calculated. The mean dry matter intake was significantly higher for cows in the second lactation (19.1 kg/day) than for cows in the first lactation (16.4 kg/day), whereas the DM-intake was constant in the different feeding groups (17.3 and 17.4 kg/day). The correlation between feed intake in the first and the second lactation was r = 0.76. The copper concentration in the serum was not influenced by the different feedings (11.9 and 12.5 micromol/l), but high variations were found between the cows. The influence of the lactation number was not significant (12.1 and 12.4 micromol/l). In contrast to copper, the zinc concentration in the serum was significantly higher for Group B (14.0 micromol/l) than for Group A (12.2 micromol/l), respectively, for second lactating cows (13.8 micromol/l) in relation to 12.7 micromol/l for first lactating cows. The individual variation was also high as for copper. Neither the correlation between copper intake and copper serum concentration nor the correlation between zinc intake and zinc serum concentration was significant.

Influence of various iodine supplementation levels and two different iodine species on the iodine content of the milk of cows fed rapeseed meal or distillers dried grains with solubles as the protein source.

Supplementation of animal feed with iodine influences the iodine content of milk and therefore, in addition to salt iodination, provides another possibility for improving the human iodine supply. On the other hand, excessive iodine intake by humans through drinking milk must be avoided. Furthermore, the iodine content of milk varies, depending on the presence of iodine antagonists in feed (e.g., glucosinolates in rapeseed) and the applied iodine species. This study evaluated the impact of various feed iodine supplementation levels up to the permitted maximum level, the effect of applying rapeseed compared with a glucosinolate-free ration, and the impact of 2 different iodine species on the iodine content of milk. A total of 32 dairy cows were divided into 4 groups with 8 animals each. Two groups received distillers dried grains with solubles (DDGS) as the protein source, and the others received rapeseed meal (RSM, 16.5% of total diet). In each case, half the animals received feed supplemented with iodine in the form of potassium iodide, and the other half received feed supplemented with iodine in the form of calcium iodate. Iodine supplementation levels of 0, 0.5, 1, 2, 3, 4, and 5 mg/kg of dry matter (DM) were tested in consecutive periods of 21 d each. The milk iodine concentration increased with increasing iodine supplementation of the feed. Rapeseed meal in the ration (0.58 mmol of glucosinolates/kg of diet DM) diminished the milk iodine concentration by up to one-half to one-third of the concentration achieved by DDGS. At iodine supplementation levels of 2 mg/kg of DM and higher, the differences were significant. The application of iodate predominantly resulted in higher milk iodine concentrations compared with iodide, but not significantly in any period. At the highest tested iodine supplementation (5 mg/kg of DM), the milk iodine concentration increased up to 1,464 (iodide) and 1,578 microg/kg (iodate) when feeding DDGS and up to 718 (iodide) and 620 microg/kg (iodate) in the RSM groups. The carry over of iodine from feed into milk amounted to 30 to 56% when using DDGS, and 11 to 25% when using RSM. The maximum level of iodine currently allowed in the feed of dairy cows in Europe could lead to high milk iodine concentrations. As a result, the Tolerable Upper Intake Level in human nutrition could be exceeded. Therefore, this maximum level needs to be reevaluated. In addition to iodine supplementation, the application of RSM in the ration must be considered when estimating the iodine content of milk.

Serum chemistry reference values in adult Japanese quail (Coturnix coturnix japonica) including sex-related differences.

Serum chemistry reference values may provide useful information about the physical condition of individuals, making them a useful tool in differentiating normal and healthy animals from abnormal or diseased states. For Japanese quail that are used for producing eggs and meat for human consumption and also as laboratory animals, we aimed to extend the available array of reference values and to compare 16-wk-old adult male versus female birds. In the present study, clinical chemistry data (albumin, total protein, glucose, uric acid, cholesterol, bilirubin, cholinesterase, creatinine, triglycerides, alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyltransferase) in blood serum from up to 125 male and 151 female Japanese quail were established. Statistical comparisons were made between male and female birds. Aspartate aminotransferase, alanine aminotransferase, glucose, cholinesterase, and bilirubin values were higher (P < 0.01) in males, whereas females had higher (P < 0.05) concentrations of albumin, total protein, gamma-glutamyltransferase, total cholesterol, and triglycerides. No significant sex-based differences were observed for creatinine and uric acid. The reference values provided are relevant in particular for the use of quail as laboratory animals when responses to specific treatments have to be monitored and appraised.

Effect of several doses of zeolite A on feed intake, energy metabolism and on mineral metabolism in dairy cows around calving.

The object of the present study was to determine the influence of different zeolite A doses on dry matter intake (DMI) and mineral metabolism, and to evaluate an optimum dosage for preventing hypocalcaemia. Eighty pregnant dry cows were assigned to four groups (I-IV). They were fed a total mixed ration (TMR) ad libitum. Groups II, III and IV received an average daily dose of 12, 23 and 43 g zeolite A/kg DM for the last 2 weeks prepartum. Individually DMI was recorded daily. Blood and urine samples were taken before, during and after zeolite A supplementation. Serum was analysed for Ca, Mg, P(i), K, non-esterified fatty acids and beta-hydroxybutyrate (BHB). Urine was analysed for Ca, Mg, P(i), K and net acid-base excretion (NABE). After calving, milk yield (fat corrected milk) and milk composition were determined. During zeolite A supplementation, mean DMI of Group IV (7.3 +/- 1.3 kg/cow/day) was significantly lower compared to Groups I-III (10.1, 10.9, 9.5 kg/cow/day). The reduced feed intake of Group IV resulted in significantly increased BHB as well as decreased NABE after calving. Zeolite A supplementation in higher doses (III and IV) had a stabilizing effect on Ca metabolism around calving for older cows, whereas cows in Groups I and II showed a subclinical hypocalcaemia. The mean serum Mg concentration decreased significantly in older cows in Group IV at calving. The mean P(i) concentration in cows of Group IV decreased into ranges of hypophosphataemia already 1 week after beginning of zeolite A feeding. The mean DMI postpartum as well as the milk yield was not affected by zeolite A supplementation. Feeding of 23 g zeolite A/kg DM TMR prepartum proved to be an adequate dosage for reducing subclinical hypocalcaemia frequency without significant effects on feed intake and P(i) concentration in serum.

Influence of fumaric acid on ruminal parameters and organ weights of growing bulls fed with grass or maize silage.

The influence of the potential methane reducer, fumaric acid (FA), on ruminal parameters, the rumen wall and organ weights was investigated in a long-term study with growing bulls. In all, 20 bulls were fed with maize or grass silage as roughage, and with concentrate with or without 300 g FA per animal and day during the whole fattening period. After slaughtering, the organs were weighed and blood serum was analysed for glucose, ß-hydroxybutyric acid (BHB) and non-esterified fatty acid concentration. The ruminal fluid was analysed for short-chain fatty acids, ammonia-N and the microbial community via single strand conformation polymorphism analysis. The rumen wall was examined histopathologically and results were graded as 'no visible lesions', 'few inflammatory infiltrates', 'some inflammatory infiltrates' or 'several inflammatory infiltrates'. In addition, the dimensions of the rumen villi were measured. The FA supplementation decreased the serum BHB concentration and the butyric acid concentration in the ruminal fluid. The microbial community in the ruminal fluid was not influenced by FA. An interaction between FA and silage type was observed for the inflammation centres counted in the villous area of rumen papillae. This interaction was also observed in the length and surface of the rumen villi. Rumen villi results show that the influence of FA depends on the roughage used in the diet.

Effects of the Fusarium toxin deoxynivalenol on tissue protein synthesis in pigs.

The Fusarium toxin deoxynivalenol is known to be a potent protein synthesis inhibitor according to research in different in vitro and in vivo systems. However, the significance of this toxic feature was not yet evaluated for the pig. Therefore, an experiment was carried out to measure porcine tissue protein synthesis employing the so-called flooding dose technique using [(2)H(5)]-phenylalanine as tracer. A total of 25 male castrated pigs (initial weight of 23kg) were used. Seventeen pigs were fed the control diet (control) and eight the Fusarium toxin-contaminated diet (chronic oral deoxynivalenol (DON)) for approximately 4wks. Pigs recruited from the control group were treated with acute oral (n=7) and intravenous (i.v.) DON (n=5), and were exposed to the toxin once on the day of protein synthesis measurement. The DON-dose given prior to the beginning of protein synthesis measurement amounted to 2, 77, 83 and 53microg DONkg(-1) live weight for the control group, chronic oral DON-group, acute oral DON-group and acute i.v. DON-group, respectively. Protein synthesis expressed as fractional synthesis rate (FSR) was significantly reduced in kidneys, spleen and ileum of DON-exposed pigs with effects being less pronounced in the acute oral DON-group. FSR of liver, skeletal and heart muscle, mesenteric lymph nodes, duodenum, jejunum, jejunal mucosa cells, pancreas and lung were not affected by DON.

Effect of addition of a detoxifying agent to laying hen diets containing uncontaminated or Fusarium toxin-contaminated maize on performance of hens and on carryover of zearalenone.

16-wk experiment with laying hens was carried out to examine the effects of feeding of mycotoxin-contaminated maize (CM) on performance, nutrient digestibility, weight of organs, serum chemical parameters, and antibody titers to Newcastle disease virus (NDV) in serum. Also tested were fimbrien antigen K88 in egg yolk and zearalenone (ZON) residues in eggs and tissues. The Fusarium-toxin-contaminated maize contained 17,630 microg deoxynivalenol and 1,580 microg ZON/kg. Moreover, Mycofix Plus (MP), a so-called detoxifying agent, was added to both the uncontaminated control (UCM) and to the CM diet (70% dietary maize inclusion). Each of the four resulting diets (UCM, UCM-MP, CM, CM-MP) was tested on 25 laying hybrids (Lohmann Brown). Feeding of the CM diets significantly depressed feed intake compared to the control groups by approximately 5%. This was mainly due to the effects observed at the beginning of the experiment. Daily egg mass production/hen was 56.6, 58.4, 53.9, and 55.2 g in groups UCM, UCM-MP, CM and CM-MP, respectively. Nutrient digestibility and metabolizability of gross energy were slightly depressed by feeding the CM diets and improved by MP addition. Feeding of the CM diets resulted in a significant decrease in serum titers to NDV and to an increase in yolk titers to antigen K88. No residues of ZON or of its metabolites were found in yolk, albumen, abdominal fat, breast meat, follicles greater than 1 cm in diameter, ovaries including follicles smaller than 1 cm in diameter, magnum, and serum. ZON and alpha-zearalenol (alpha-ZOL) were detected in livers of hens fed the CM diets at mean concentrations of 2.1 and 3.7 microg/kg, respectively. It was concluded that feeding maize which was highly contaminated with Fusarium mycotoxins adversely influenced performance of hens and modulated immune response. At the given level of zearalenone and at the indicated detection limits, no residues of ZON and its metabolites were found in eggs. The effects of the tested detoxifying agent were quite mycotoxin-independent.

[Animal-derived feeds as possible vectors for bovine spongiform encephalopathy (BSE) in Germany. 1. Comparative risk assessment for a single animal food of animal origin]. / Futtermittel tierischer Herkunft als mögliche Verbreitungsursache für die bovine spongiforme Enzephalopathie (BSE) in Deutschland: 1. Mitteilung: Vergleichende Risikobewertung der Einzelfuttermittel tierischer Herkunft.

The occurrence of BSE cases in Germany after the ban of meat and bone meal for ruminant feed in 1994 requires a detailed investigation of animal derived feedstuffs regarding their specific risks as vectors for the disease. Accepting the theory that BSE is a prion transmitted disease, the theoretical infectious potential was calculated for animal derived feedstuffs. This calculation was based on the assumption, that risk material (brain, spinal cord) of one clinically diseased cattle was rendered in the process as established in Germany (133 degrees C, 3 bar, 20 min) or, alternatively, that one diseased animal was slaughtered resulting in normal processing of the by-products for human food production. From this risk assessment it became obvious that meat and bone meal was one, but probably not the most important source for the spreading of BSE. Taking into account the high sensitivity of calves it can be speculated that certain products, e.g. from bone processing (bone meal) and fat melting (mixed animal fats), commonly used for the formulation of milk replacers, might have been more important as pathways. As it can't be excluded retrospectively that infected meat and bone meal was imported from the UK, this non-calculable influence may have been related to the significance of the other products. The calculation model underlines that efficient removal of specified risk material (brain, spinal cord) and adequate processing (133 degrees C, 3 bar, 20 min) or alternatively other equivalent treatments of fats are prerequisites for minimising the risk of feed borne transmission of BSE by animal derived feedstuffs. The epidemiological consequences are part of a subsequent paper.

[Animal-derived feedstuffs as possible vectors for bovine encephalopathy (BSE) in Germany. Part 2: Assessment of vector risk for compounded feed]. / Futtermittel tierischer Herkunft als mögliche Verbreitungsursache für die bovine spongiforme Enzephalopathie (BSE) in Deutschland. 2. Mitteilung: Einschätzung des Verbreitungsrisikos über Mischfutter.

Specific conditions and practices of cattle feeding in Germany have to be taken into account for assessing the risk of feed born transmission of bovine spongiform encephalopathy, especially regarding the situation before the year 2000 when specific directives were introduced for feed production. The present retrospective epidemiological study includes data on feed production and the estimated amount of animal derived feedstuffs for the production of compounded feed for cattle. Risk assessment was performed based on the 'reproduction rate' (R0), that is defined as the estimated number of infections resulting from the processing of brain and spinal cord of BSE affected cattle that is recycled to bovines via feed. Under the conditions as given in Germany until the year 2000 the reproduction rate of BSE via the inclusion of animal derived feedstuffs in compounded feed production for cattle was estimated to be 1.1. Thus, it can be expected that BSE could be reproduced in the system, but with comparatively low efficiency. The expected incidence of BSE should be considerably lower compared to the situation during the 90th in the UK, due to the markedly lower recycling rate of animal protein in cattle feeding. Animal fat could have been a significant factor for BSE transmission due to contamination by proteinaceous brain and spinal cord material during the production process. The relative significance of fat containing feedstuffs for BSE transmission could have been higher in Germany compared to the situation in the UK where meat and bone meal was produced under different conditions and frequently used in higher proportions as an ingredient for compounded feed for ruminants.

Perspectives for feed-efficient animal production.

Modern animal breeding programs are largely based on biotechnological procedures, including AI and embryo transfer technology. Recent breakthroughs in reproductive technologies, such as somatic cell nuclear transfer and in vitro embryo production, and their combination with the emerging molecular genetic tools, will further advance progress and provide new opportunities for livestock breeding. This is urgently needed in light of the global challenges such as the ever-increasing human population, the limited resources of arable land, and the urgent environmental problems associated with farm animal production. Here, we focus on genomic breeding strategies and transgenic approaches for making farm animals more feed efficient. Based on studies in the mouse and rat model, we have identified a panel of genes that are critically involved in the regulation of feed uptake and that could contribute toward future breeding of farm animals with reduced environmental impact. We anticipate that genetically modified animals will play a significant role in shaping the future of feed-efficient and thus sustainable animal production, but will develop more slowly than the biomedical applications because of the complexity of the regulation of feed intake and metabolism.

The influence of an increased cobalt supply to dairy cows on the vitamin B status of their calves.

In the experiment the influence of an elevated oral cobalt supply (Co content in the ration 0.27 mg Co/kg DM; supplement of 0.14 mg Co/kg DM as CoSO(4)) to pregnant dairy cows on the vitamin B(12) concentration in milk, colostrum and vitamin B(12) status of their calves was tested in comparison with unsupplemented controls (0.13 mg Co/kg DM). While there was no significant difference in vitamin B(12) concentration in the at 70th day of lactation (start of the experiment; 3.77 +/- 1.41 vs. 3.66 +/- 1.03 ng/ml) and 290th day of lactation (almost drying off; 4.75 +/- 3.05 vs. 4.44 +/- 0.96 ng/ml), cobalamin concentration in the milk colostrum showed a tendency towards a higher cobalt content in the ration of the supplemented cows in comparison with the controls (21.0 +/- 8.4 vs. 16.7 +/- 11.9 ng/ml). Differences in the vitamin B(12) concentration in the serum of the newborn calves before and after ingestion of colostrum were not detected. From these results it can be concluded that cobalt content of 0.13 mg Co/kg DM in the ration based on wilted grass silage seems to be sufficient for pregnant dairy cows.

Effects of defaunation on fermentation characteristics and biotin balance in an artificial rumen-simulation system (RUSITEC) receiving diets with different amounts and types of cereal.

Biotin is required by rumen microbes for efficient fermentation. To evaluate the role of protozoa in ruminal biotin metabolism, five diets composed of grass hay or of grass hay/cereal grain mixtures were supplied to faunated or defaunated RUSITEC fermenters. In the mixed diets, hay was replaced to 33:67 or 67:33 w/w on an air-dried basis by either wheat or maize grain in order to simulate different cellulolytic and amylolytic fermentation conditions. Defaunation increased SCFA production, whereas NH4 concentration and the release of CH4 were reduced. Biotin input declined when cereal grain was used to replace the hay. With the exception of the high-wheat treatment, defaunated fermenters yielded higher biotin outputs than faunated fermenters. The biotin balance, calculated as the difference between the total biotin output (biotin in the solid residue contained in the nylon bags after fermentation plus the biotin in the effluent) and the biotin input with the feed, was negative for all the dietary treatments apart from fermenters supplied with the high-maize diet. It was less negative or, in the case of the high-maize diets, more positive for defaunated compared with faunated fermenters. It was concluded that, under normal faunated conditions, protozoa directly utilise or indirectly affect the bacterial synthesis and/or utilisation of biotin. With diets of a high fermentation potential, as realised with the high-wheat diet, protozoa prevent the development of a bacterial population that would utilise high or synthesise low amounts of biotin.

Effects of level of feed intake and Fusarium toxin-contaminated wheat on rumen fermentation as well as on blood and milk parameters in cows.

The aims of this study were to examine the effects of and possible interactions between dry matter (DM) intake and feeding Fusarium toxin-contaminated wheat on ruminal fermentation, serum chemical parameters and milk yield of dairy cows. Fourteen dairy cows equipped with ruminal and duodenal cannulas were analysed. All animals were fed the same ration, the daily feed amounts being adjusted to current performance. On DM basis, the ration consisted of 60% concentrate including 55% wheat [Fusarium-contaminated wheat (mycotoxin period) or control wheat (control period)] and was completed with 40% maize and grass silage. Each cow was fed the contaminated wheat [deoxynivalenol (DON), 8.21 mg/kg DM and zearalenone (ZON), 0.09 mg/kg DM] and the control wheat (0.25 mg DON/kg DM and 51 microg ZON/kg DM). As expected, a higher organic matter (OM) intake decreased the amounts of fermented crude nutrients related to the respective intakes. An increased amount of crude protein degraded (p < 0.05) and a lower molar percentage of propionate in the rumen fluid were observed when feeding the Fusarium toxin-contaminated wheat at increased OM intakes in comparison with the control wheat. The activities of serum aspartate aminotransferase (ASAT; p < 0.001), glutamate dehydrogenase (GLDH; p < 0.01) and gamma glutamyl transferase (gamma-GT; p < 0.01) increased with increasing OM intake and were not related to the mycotoxin contamination of the wheat.