Photosensitisation and green egg yolks in laying hens caused by the feeding of ensiled alfalfa leaves.

1. The present study was carried out to determine the effects of feeding ensiled alfalfa leaves (ALS) as an alternative protein source to laying hens under the terms of an organic diet. Due to the occurrence of unexpected negative health effects and undesirable egg yolk pigmentation in the test groups the trial was prematurely stopped and further analysis was conducted to evaluate the responsible substances.2. Body weights of the test groups decreased significantly already in week 2 of the trial. Performance variables dropped. Olive green pigmented egg yolks were found in groups fed diets containing ALS. Severe comb necrosis occurred in the experimental group receiving the highest level of ALS (20%) combined with the option of free-range access and therefore natural light exposure.3. The noxious agent found in ALS, blood serum and egg yolk was the photosensitising chlorophyll derivate pheophorbid a (PPBa), deriving from a strong depletion of chlorophyll contained in the alfalfa leaves. PPBa caused the olive-green pigmentation found in yolks and led to photosensitivity in groups with the highest level of ALS in the diet in combination with light exposure.4. By aiming for high protein and amino acid levels, harvesting and processing have, unintentionally and initially unnoticed, led to a strong accumulation of phototoxic PPBa. From these results it is strongly advised not to include ensiled alfalfa leaves as a protein source in organic laying hen diets.

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.

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.

Studies on the mode of action of non-starch-polysaccharides (NSP)-degrading enzymes in vitro. 2. Communication: effects on nutrient release and hydration properties.

By use of an in vitro model, the effects of NSP-degrading enzymes on the cage effect and the hydration properties were demonstrated using wheat bran. The in vitro model simulates the conditions (pH, dry matter, temperature and transit time) in the fore sections of the porcine gastro-intestinal tract (GIT) by neglecting endogenous enzyme activities. Enzyme treatment caused a dose-dependent increase in wheat bran solubility and thus resulted in improved protein and mineral release from the insoluble NSP fraction. Up to 17% protein and 40% crude ash from the insoluble NSP-fraction were dissolved after enzyme treatment. Hydrating properties of wheat bran were strongly affected by enzyme treatment and particle size. Water-binding capacity (WBC) and water-holding capacity (WHC) decreased with increasing enzyme dosage in dependence on particle size. The studies confirmed the applicability of the tested in vitro model as a useful tool for preliminary tests to estimate the effects of NSP-degrading enzymes on nutrient release and changes in some physico-chemical properties.

Studies on the mode of action of non-starch-polysaccharides (NSP) degrading enzymes in vitro. 1. Communication: effects on the fractions of NSP.

An in vitro model using the model substance wheat bran as NSP source was developed to study the effects of NSP degrading enzymes (xylanase and beta-glucanase) on NSP fractions. The in vitro model simulates the conditions (pH, dry matter, temperature and transit time) in the fore sections of the porcine gastrointestinal tract. By neglecting endogenous enzymes the sole effect of the added enzymes could be investigated. By application of the enzyme complex, a significant degradation of the insoluble NSP fraction was observed in all sections of the porcine gastro-intestinal tract simulated by the in vitro model. A strong dose dependent effect was determined. Compared to the control, the arabinose/xylose-ratio generally increased but differences were found between the sections simulated. Considering the arabinoxylans in the soluble NSP fraction, the effect of enzyme supplementation was reflected by a change in the arabinose and xylose contents. In comparison to the control, an increase in the amounts of arabinose and xylose was observed at low enzyme doses applied. However, with increasing enzyme activities the amount of arabinose and xylose declined. The in vitro model is considered as a useful tool for preliminary tests to estimate the effects of NSP-degrading enzymes on NSP fractions in the fore sections of the porcine gastro-intestinal tract.

Research note: effect of duodenal--infused unsaturated fatty acids on dairy milk composition.

Investigations were conducted to assess the effect of duodenal infusions of oleic and linoleic acids both on milk composition and fatty acid patterns of milk fat. The investigations were carried out in two trials, I and II, each with 3 cows, fitted with a ruminal and a duodenal cannula. 56 g of oleic acid (Trial I) and 46 g linoleic acid (Trial II) were infused daily into the duodenum over a period of 7 days, while no application of fatty acids acted as a control in each case. An increase in milk fat content was observed in both trials whereas the content of protein and lactose in milk remained unaffected. In both trials the milk oleic acid and linoleic acid concentrations increased. In trial I C18:1 increased from 14.8 to 18.7%. In trial II C18:2 increased from 2.5 to 5.8% of total lipids. It was estimated that 84.8% of the infused C18:1 and 86.5% of C18:2 were transferred into milk fat.