Gerhard Flachowsky

New feeds from genetically modified plants: substantial equivalence, nutritional equivalence, digestibility, and safety for animals and the food chain

Abstract The introduction by recombinant DNA technology of new genes into major crops used by animals has raised important questions about the safety of novel feeds. The recently amended European Council Directive 2001/18/EC requires an assessment of risks for human, animals and the environment before viable seeds can be imported or the plant itself can be cultivated in Europe. In addition, the Novel Food and the Novel Food Ingredient Regulation (EC Council Directive, 1997) covers the use of non-viable products of any genetically modified (GM) plant intended for food purposes. The conceptual basis for the analysis of risks remains that of substantial equivalence. In practice, compositional analysis of key nutrients and key toxicants used to compare a GM plant with its conventional counterpart is the major source of data used to establish substantial equivalence. Although laboratory animals are used in toxicological studies of the products of introduced genes, animals are rarely fed the entire transformed plants or their by-products. Despite not being required or recommended by the existing legislation, many new products have been intensively tested with farm animals to measure effects on performance and animal health, digestibility of key nutrients, wholesomeness and feeding value. In this paper, we consider the value of such studies for establishing the safety of GM feedstuffs for the target animals and whether animal feeding studies are always necessary to establish the safety for the consumer of products of animals fed GM material. Compositional analysis has always shown the genetically modified plants to fall within the range of established values. The equivalence in digestible energy and crude protein between isogenic and transformed plants expressing a wide range of modifications (insect resistance, herbicide tolerance, or the barnase/barstar system of sterility/fertility restoration genes) also has been clearly demonstrated in different species. In none of these experiments was animal performance, whether measured as growth rate, feed efficiency and carcass merit in beef cattle, egg mass in laying hens, milk production, composition and quality in dairy cows or digestibility in rabbits, affected by feeding transformed plants compared to animals fed control or isogenic plants. Detection of chloroplasts-specific gene fragments by polymerase chain reaction showed the presence of plant DNA fragments (199 base pairs) in lymphocytes and duodenal juice of the dairy cow, and in muscle, liver, kidney and spleen of broilers. However, tDNA expressing Bt , usually found as a single copy gene, could not be detected in milk, tissues sample or eggs of livestock fed Bt maize and is probably not cause for concern.

Genetically modified feeds in animal nutrition 1st communication: Bacillus thuringiensis (Bt) corn in poultry, pig and ruminant nutrition

During the last few years, animal nutrition has been confronted with genetically modified organisms (GMO), and their significance will increase in the future. The study presents investigations on the substantial equivalence of the transgenic Bt (Bacillus thuringiensis) corn and the corresponding nontransgenic hybrid Cesar and parameters of nutrition physiology such as digestibility and energy content for poultry, pigs and ruminants. The results of the analysed corn samples as well as of the silage samples illustrated substantial equivalence in all investigated ingredients, such as crude nutrients, amino acids, fatty acids, minerals and non‐starch polysaccharides. The results of the experiments using poultry, pigs, wethers and fattening bulls were not influenced by the genetic modification of corn. The determined values for the digestibilities and the energy contents for poultry, pigs and wethers were not affected by the used corn variety. Neither the examined parameters of the fattening experiments with bulls nor the slaughter results showed any significant differences between the bulls fed on silages made from the nontransgenic or transgenic corn.

Eggs and poultry meat as tocopherol sources in dependence on tocopherol supplementation of poultry diets

Abstract One feeding trial with broilers and three feeding experiments with layers were carried out to investigate the influence of various vitamin E supplementations on α-tocopherol concentration of foods of poultry origin. Vitamin E content of basal diets amounted to ≈20 mg per kg feed; 0, 100, 1000, 10 000 and 20 000 mg vitamin E per kg feed were added. Broilers were fed for 30 days and slaughtered, layers were kept for one laying year (13×28 days), eggs were collected daily. Vitamin E concentration was determined in muscle (breast, legs), liver, fat and eggs by HPLC. Tocopherol concentration increased with vitamin E supplementation in all samples. The highest tocopherol concentration was measurement in egg yolk (254.9) followed by liver (44.8) and muscle (12.2 mg/100 g). Vitamin E supply of poultry feed depends on costs of vitamin E and financial benefits for the farmer.

Genetically modified feeds in animal nutrition. 2nd communication: glufosinate tolerant sugar beets (roots and silage) and maize grains for ruminants and pigs.

To analyse substantial equivalence of genetically modified sugar‐beets and maize, in which the glufosinate‐tolerant (Pat) gene is inserted, crude nutrients, the amino acid and the fatty acid profiles as well as the composition of the NDF‐fraction of maize grains were determined and compared with those of the corresponding non‐transgenic cultivars. Due to the genetic manipulation differences in crude nutrient contents including sugar and starch were not detected. The amino acid profile of maize grains was analysed to be the same. Fatty acid profile and composition of cell wall constituents did not show any influences as well. Digestibility of Pat‐sugar‐beets and maize grains for pigs did not demonstrate meaningful differences as compared to the corresponding non‐transgenic cultivars. Digestibility of sugar‐beet roots and sugar‐beet top silage for ruminants proved to be also in the scope of natural variance. As the digestibility of the macro nutrients remained unaffected, the Pat‐gene introduction into both crops did not show an influence on the energetic feeding value. For pigs the ME‐content of Pat‐sugar‐beets was determined to be 14.1 MJ/kg DM versus 13.7 MJ of the non‐transgenic cultivars. ME‐content of Pat‐maize grains was 16.0 MJ/kg DM versus 15.8 MJ for controls. For ruminants the feeding value of Pat‐sugar‐beets was found to be 8.5 MJ NEL/kg DM or 13.2 MJ ME/kg DM, regardless of whether the Pat‐gene was inserted or not. The corresponding energy values of sugar‐beet top silage ranged between 5.2 and 5.5 MJ NEL/kg DM or 8.6 and 9.1 MJ ME/kg DM, with differences considered in the biological range.

Influence of oilseeds in combination with vitamin E supplementation in the diet on backfat quality of pigs

Abstract To study combination effects of oilseeds and vitamin E supplements in the diet on backfat quality, two feeding experiments with a total of 60 growing-finishing pigs were designed. Experiment 1 (24 pigs) included a control group with a cereal/soybean-meal diet and two experimental groups with 100 g kg −1 rapeseed or 200 g kg −1 full-fat soybeans, resulting in an increase of ether extract from 28 to 74 or 69 g kg −1 respectively. Three weeks before slaughter, four animals of each group were fed additionally with 1 g α-tocopherol acetate per animal per day. In experiment 2, four groups of nine pigs each received a cereal/soybean meal diet, and 0, 1, 2 and 3 weeks before slaughtering, the animals were given 1 g α-tocopherol acetate per day. Tocopherol concentration in blood, liver, muscle and backfat was determined by applying the HPLC technique. In addition, the fatty acid pattern of the backfat was analyzed using capillary gas chromatography and the oxidative stability of the fat was determined using the Rancimat test. In experiment 1, oilseed influenced the fatty acid pattern of the backfat. The percentage of linolic and linolenic acid increased significantly and a tendency towards lower proportions of saturated fatty acids was detected. However, the full-fat soybean diet decreased the percentage of oleic acid significantly. Vitamin E supplements three weeks before slaughter increased vitamin E concentration of backfat from 12.3 to 31.1 mg kg −1 . The response to dietary α-tocopherol intake in the various organs was found to be in the sequence liver > subcutaneous fat > serum > muscle. Oxidative induction time of backfat varied between 2.9 and 13.7 h depending on the fatty acid pattern and the vitamin E concentration. The shortest induction times were observed when oilseed without vitamin E supplements were fed. The longest times were observed after feeding the soybean/cereal diet with vitamin E supplements. In experiment 2, vitamin E concentration of backfat was much lower (ranging between 7.0 and 12.8 mg kg −1 ) than in experiment 1. Vitamin E administration over three weeks doubled vitamin E concentration in backfat and also induction time. Results demonstrate the antioxidative effects of vitamin E and its meat quality improving properties.

Niacin in dairy and beef cattle nutrition

Niacin functions metabolically as a component of the coenzymes NAD and NADP. Sources of niacin are feedstuffs and the enzymatic conversion of tryptophan and quinolinic acid into niacin. Niacin is synthesized by the microflora in the rumen of ruminants. Recent research suggests that microbial production of niacin may not be sufficient for the requirements of high producing cows. Supplemental niacin given to cows in early lactation may reduce the rate of fat mobilization, decrease the concentration of ketones in blood and increase blood glucose level. Niacin supplementation may increase propionate concentration and decrease butyrate concentration in rumen liquor. Ruminal microbial protein synthesis was enhanced by niacin. Not all experiments showed such clear results. The positive metabolic effects of niacin supplementation have resulted in most studies in an improved milk yield (3-4%) especially during early lactation. The milk constituents were mostly uninfluenced or only minimally increased. Reasons for the high variations of results are differences in ration formulation, level of milk performance, stage of lactation, age of cows, body conditions, level and duration of niacin supplementation and specific experimental conditions. Niacin supplemented cows lost less body weight during early lactation, were less days open and required fewer pellets per pregnancy. It would appear that niacin supplementation of about 6 grams per animal per day (200-400 mg per kg dry matter) for the first 60 to 100 days of lactation may be beneficial in selected high producing cows or heifers. In beef cattle niacin supplementation would appear to be beneficial (approximately 1 g per animal per day or about 100 mg per kg dry matter) when the body weight of bulls is lower than 300 kg, when the diets are poor in protein (10 tp 12% crude protein of dry matter) and during dietary adaptation periods.

Evaluation of straw treatment with ammonia sources on growing bulls

Energetical and ecological aspects of straw ammoniation were calculated based on five feeding trials with growing bulls consuming untreated, ammonia or urea treated wheat straw. Dry straw was gased with ammonia (3.0–3.2%) and wet straw (38.1–56.3% dry matter, DM) was treated with urea (2.5–5% on DM base). In digestibility experiments with sheep and feeding trials with 104 growing bulls fed treated and untreated straw was compared. Bulls consumed 2 kg concentrate per day and untreated or treated straw ad libitum. In two experiments ammonia or urea treated straw was given in adequate amounts to untreated straw (pair feeding). Based on the results of feeding trials energetic input (60 or 80 MJ per kg N from ammonia or urea) and ecological output (NH3, CO2) were calculated. Ammoniation increased apparent digestibility of organic matter of wheat straw from 43.9 to 52.7%, urea treatment enhanced it from 46.5 to 53.0% on average. Pair feeding of ammonia or urea treated wheat straw resulted in an increase of daily liveweight gain amounting 69 and 55 g day−1. Ad libitum intake of treated straw increased daily weight gain with range of 75 to 290 g. Animal growth rate was used to evaluate the different straw treatments with regard to the ammonia sources. Between 0.8 and 7.0 kg body weight were produced per kg N added to the straw due to higher digestibility and increased straw intake. Assuming a conversion rate of 5 kg grains for 1 kg beef, one kg N used as fertilizer has at least to increase the yield of cereals in the range of 3.8 and 35 kg, otherwise the N-utilization on the field would be less efficient. Low animal response to ammoniation of straw resulted in high fossil energy needs per animal and high environmental pollution. More dose-response trials are necessary to allow a better evaluation of N-efficiency in straw treatment.

Influence of the ratio between wheat straw and ground barley, ground corn or dried sugar beet pulp on in sacco dry matter degradation of ryegrass and wheat straw, rumen fermentation and apparent digestibility in sheep.

Castrated male sheep were fed with 5 different rations varying in the straw to concentrate ratio between 100: 0, 75: 25, 50: 50, 25: 75 and 0: 100. Ground barley, ground corn and dried sugar beet pulp were used as concentrate sources. Chopped winter wheat straw was fed as roughage source. All rations were supplemented with a protein-mineral-vitamin-premix. In sacco dry matter degradability of artificially dried ryegrass, untreated and ammonia treated wheat straw was measured within three rumen fistulated sheep. Nylon bags were incubated for 48 h in the rumen of sheep. Volatile fatty acids of rumen fluid were determined by gas chromatography. Samples were taken via rumen fistula 3 h after morning feeding. Apparent digestibility of organic matter and fibre fractions of total rations were determined within five sheep. Increased concentrate portion decreased in sacco dry matter degradability of incubated roughages. Decrease of dry matter degradability was much higher for ammonia treated (from 55.0 to 22.5%) and untreated straw (from 50.9 to 22.7%) than for ryegrass (from 75.6 to 69.2%), when concentrate increased from 0 to 100% of ration. The highest concentrate portions did not show any increase of degradability of ammonia treated straw. Specific concentrate effects were observed when 75 and 100% concentrate were fed (unphysiological level). Ground barley as concentrate source decreased rumen pH to a larger extent (down to 5.18) than corn and sugar beet pulp (down to 5.60 and 5.57). Sheep suffered from rumen acidosis in some cases. Higher concentrate levels increased concentration of total volatile fatty acids of rumen liquid and molar concentration of propionate and butyrate, but decreased acetate. Various concentrate sources showed different influences on parameters of rumen fermentation. Apparent digestibility of organic matter of total rations increased from 52.7 to 86.1% if concentrate portions enhanced from 0 to 100%. High portions of ground barley decreased cellulolytic activity and fibre digestion. On the other hand high levels of sugar beet pulp increased digestibility of crude fibre and neutral detergent fibre.

Influence of high vitamin E dosages on retinol and carotinoid concentration in body tissues and eggs of laying hens

The aim of the study was to contribute to the discussion of overdosing vitamin E in laying hens. A total of 45 laying hens, divided into 5 groups were fed diets supplemented with either 0; 100; 1000; 10 000 or 20 000 mg dl‐α‐tocopheryl acetate/kg diet over a period of 10 weeks. Concentrations of vitamins A and E were measured in plasma, various tissues and egg yolk. Furthermore egg yolk colour and some carotinoids were measured in egg yolks. None of the vitamin E doses significantly influenced performance of the hens. As expected, vitamin E concentration in plasma, all tissue samples and egg yolk was significantly increased with increasing tocopherol content in the diet. The egg yolk showed the highest vitamin E concentration, followed by liver and muscles. Feeding 1000 mg α‐tocopheryl acetate per kg diet resulted in an increase of vitamin A concentration in the liver. Very high doses (10 000 and 20 000 mg/kg diet) significantly decreased retinol concentration in the liver and egg yolk, as well as carotinoid concentration in the egg yolk. The lower carotinoid concentration in egg yolk resulted in a decreased intensity of egg yolk colour. A prooxidative and/or competitive effect of very high doses of vitamin E with other fat soluble substances has been discussed.

Feed value and feeding of wastelage made from distillers grain solubles, pig slurry solids and ground straw treated with urea and NaOH.

Urea at five levels (0, 1, 2, 4 and 6%) and NaOH at two levels (2 and 4% of dry matter to each of 2 and 4% urea level) were added to a mixture consisting of seven parts distillers grain solubles, two parts pressed pig slurry solids and one part ground wheat straw, on a fresh weight basis. After a fermentation period of 42 days at ambient temperature in 100-litre capacity silos, the pH dropped in the unsupplemented wastelage (3·90), but it increased after urea and NaOH supplementation (up to 7·14). Ammonia and acetate concentrations in wastelage were enhanced with urea addition. Increase of acetate and butyrate concentration was observed when NaOH was added. In sacco degradability increased from 49·0% (untreated sample) to 67·0% when 2% urea and 4% NaOH were added. The rumen dry matter degradability of wastelages was significantly higher when sheep consumed a diet rich in roughages (57·5%) rather than a concentrate ration (50·1%). Sheep consumed about 1 kg dry matter daily when unsupplemented or when 1% urea-added wastelage was fed. Higher levels of chemicals decreased dry-matter intake. Chemically-treated wastelage replaced about a half of wilted grass silage without any negative effect on daily weight gain in short-term feeding experiment with growing bulls.