KA4CG2HT

5665

8 janvier 2023 15:23

8 janvier 2023 15:33

Riboflavin (Vitamin B2) is an essential vitamin for all non-ruminant livestock animals. Also poultry feed formulations need to contain riboflavin, in order to avoid disorders in energy metabolism, oxidation protection of lipids, growth and neuronal control of the limbs. With increasing growth or laying performance of modern genotypes, these requirements raise due to higher metabolic turnover. This holds true also for organic poultry. In organic systems, however, low inputs of artificial or isolated substances to animal feed are aspired. Furthermore, the ban of GMObased substances in organic production cycles requires separate GMO-free production lines for the microbiological production of riboflavin. Such production lines are on smaller scales and with less efficient organisms, thus, more expensive. Given this background, riboflavin supplements to organic poultry should be as low as possible, with safe margins regarding animal health, welfare and productivity. Specific recommendation figures for organic systems do not exist, however, there are reasons to assume somewhat lower requirements than in conventional systems, due to slightly lower growth rates and other feed formulations. Furthermore, the scientific basis of current conventional recommendations are rather outdated. For these reasons, the goal of the present work was to generate experimental evidence for safe lower levels of riboflavin supplementation to organic poultry feed formulations. These implied in separate approaches fattening broilers, laying hens, as well as breeding hens and their offspring. At the same time, a new European GMO-free riboflavin product has replaced the previously widely used product, which had been produced in China and was recently taken off market. We therefore also tested and approved the equivalence of the new product with conventional commercially available GMO-based riboflavin. Broiler diets were tested in four different experiments with slow-growing genetical strains fattened with organic feed formulations during 55-63 days. A total of 12 different riboflavin supplementation schedules were tested, ranging from zero to 9.6 mg supplementation per kg of feed, always applying the European product Ecovit R (Agrano GmbH, Riegel, Germany). Impaired growth rates as a sign of riboflavin deficiency were found with supplementation levels 0, 2.5, and 3.5 mg/kg, in different experiments. However, in other experiments, also supplementation levels below 3.5 mg/kg performed without causing deficiency symptoms. Note that all biological feed components contain intrinsic riboflavin (range 1.5-3.5 mg/kg), which adds to the supplemented. Altering levels of intrinsic contents caused different responses supplementation levels. Considering these alterations of native riboflavin contents, we conclude 4.0 mg/kg supplementation to be a generally safe level for growing chicken. Supplementation graded by phases proved to perform well, however practical applicability of grading schedules appears less likely. With respect to laying hens, including breeders, we tested five levels of supplementation from 1.5 to 4.5 mg/kg. None of these supplementation levels caused any depressions in laying performance nor impaired health scores. However, with supplementation of 1.5 mg/kg, we found reduced riboflavin concentrations in egg yolks and livers, which are considered as first signs of riboflavin deficiency. Since no such differences occurred between supplementation levels of 4.5, 3.0 and 2.5 mg/kg, we conclude a homeostatic equilibrium in this range. Therefore, 3.0 mg riboflavin / kg feed are considered a safe supplementation level for laying hens fed organic diets. Breeder hens were examined with respect to their own performance and health, including egg fertility, hatchability and subsequent growth development of the hatched broiler chicks. We compared supplementation levels 4.0 and 2.5 mg/kg in one experiment. Although no signs of deficiency occurred with the hens, the fertility and the hatchability, growth performance of chicks from low-supply parents was clearly impaired. Chicks from the control group (4.0 mg/kg) developed according to the usual growth rates of the genetic strain investigated (Hubbard S757), but chicks from low-supply parents showed less than 90% of the growth rate with clear statistical significance. A similar effect was found with a low supplementation level for the chicks themselves, when their parents had been supplied normally. An additive depressive effect of low supplementation of parents and offspring was not found. Health impacts due to the different supplementation levels of breeding hens were generally not found. The conclusion is that for breeding hens a supplementation with 4.0 mg riboflavin per kg feed is sufficient but necessary in order to prevent growth depressions of the offspring. Full detailed information on all experiments is provided in four scientific publications (section 2.2). Two manuscripts are still confidential until online publication by the journals

None

• AB - Spécifique
• RELACS
• organic feed
• poultry
• requirements
• riboflavin
• vitamin b2

6

30/04/2021

30 avril 2021