Lysine is an essential amino acid for all animal species; it is the first limiting amino acid in swine nutrition and the second limiting amino acid in poultry nutrition. L-Lysine and its salts are widely used in the feed industry to optimise dietary protein.Neither the production strain nor its recombinant DNA was detected in any of the final products. The final products do not raise any safety concern with regard to the genetic modifications.Concentrated liquid L-lysine (base), concentrated liquid L-lysine HCl and L-lysine HCl technically pure are considered safe for target species when supplemented in appropriate amounts.Lysine produced by E. coli (FERM BP-10941) is not genotoxic and the results of subchronic studies do not indicate any specific concerns. As there are no lysine metabolites associated with safety concerns in the animal tissues and products, the FEEDAP Panel considers that the use of L-lysine and its hydrochloride salts in animal feed does not pose a risk for the consumer.Concentrated liquid L-lysine (base), concentrated liquid L-lysine HCl and L-lysine HCl technically pure are not considered to have the potential to cause respiratory toxicity, skin or eye irritation or skin sensitisation, but respiratory sensitisation cannot be excluded.L-Lysine is a substance naturally occurring in bacteria, plants and animals. The use of L-lysinecontaining feed additives does not represent a risk to the environment.Concentrated liquid L-lysine (base), concentrated liquid L-lysine HCl and L-lysine HCl technically pure are considered equivalent in terms of L-lysine availability to the target animals. The efficacy of supplementing L-lysine and its hydrochloride salts is extensively demonstrated in the literature for mammals (except ruminants), poultry and fish, including its use in a liquid or a powder form. Therefore, it does not require any further demonstration. Response in ruminants requires some degree of protection of L-lysine from ruminal degradation.

The influence of dietary CLA isomer(s) and/or selenized yeast on the growth, concentration of CLA isomers and other fatty acids in the liver was investigated in rats. Plasma blood triacylglycerols (TAG), total cholesterol (TC), HDL and LDL cholesterol fractions in relation to dietary CLA isomer(s) and/or selenium (Se) were analysed. The experiment was performed on female rats (Wistar), 8 weeks of age and initial body weight of about 200 g. After a 1-week preliminary period, for 4 weeks the animals were fed a diet enriched in conjugated linoleic acid (CLA) isomer(s) and selenized yeast (2×2 experimental design). Dietary Se or/and CLA isomer(s) resulted in small changes in the spleen, heart, kidneys and brain, and increased liver weight. Administration of Se and trans10cis12CLA most efficiently increased the body weight gain of rats. CLA isomer(s) administered with or without Se elevated the CLA isomer(s) level in the liver. These results demonstrate that trans,transCLA isomers are metabolized more slowly, while cis,trans/trans,cisCLA isomers, more rapidly to longchain fatty acids containing a conjugated double bond. Enrichment of the diet in CLA isomer(s) with or without Se caused a reduction in the capacity of Δ9-, Δ6-and Δ5-desaturases in the liver, while dietary trans10cis12CLA or the CLA isomer mixture increased Δ4-desaturases. The contents of oleic acid, C20:4n-6, and C20:5n-3 decreased in the liver, whereas the level of C22:5n-3 and C22:6n-3 increased in the liver of rats fed the CLA isomer mixture. Individual dietary CLA isomers with or without Se increased the concentration of palmitic and stearic acids in the liver. All experimental diets increased the concentration of triacylglycerols in blood plasma, while trans10cis12CLA with or without Se usually decreased the concentration of total cholesterol, LDL, and HDL cholesterol.

Kuricová S., K. BoldiÏárová, ª. Gre‰áková, M. Levkut, ª. Leng: Chicken Selenium Satus When Fed a Diet Supplemented with Se-Yeast. Acta Vet. Brno 2003, 72: 339-346. This experiment was designed to investigate the effects of the feed supplementation with inorganic and organic forms of Se on the activity of blood glutathione peroxidase (GSH-Px) and the Se levels in blood and tissues in young female chickens of the laying strain Isa Brown. The first group of birds received the basic diet (BD) with Se content 0.12 mg . kg -1 of dry matter (DM). Diets for Groups 1, 2 and 3 consisted of BD supplemented with sodium selenite 0.2 mg·kg -1 of DM, Se-enriched yeast 0.2 and 0.7 mg·kg -1 of DM, respectively. The experiment lasted from hatching until 7 weeks of age. The activity of blood GSH-Px was found to be dose-dependent throughout the experiment with no differences due to the form of Se administered. The selenium analysis in blood and liver samples revealed also the Se dose dependent responses but with significantly higher values recorded in chickens aged 5 weeks and older chickens and supplied with the equivalent amounts of organic Se source. Other tissue Se levels were also highest (P < 0.05) in the group with its largest intake. The values of Se content in the breast muscle were higher (P < 0.001) in chicks of Group 3 during entire experiment and they reached the doubled values than in the birds given selenite (11.54 ± 0.4 vs. 5.47 ± 0.2 µmol·kg -1 of DM, in 7-weekold birds). On the other hand, no differences in this parameter were determined between the chicks fed just BD or BD supplemented with Na 2 SeO 3 . At the end of experiment, the intake of Se-yeast (Group 3) resulted in significantly (P < 0.05) higher Se levels in the heart, in lungs and in the gizzard than BD with selenite. No effects of the form of selenium used could be found in the spleen and kidney samples of 7-week-old chicks. The results demonstrate the evident advantage of supplementation of poultry feed with the selenium-enriched yeast due to more effective Se utilization and formation of mobile body deposits of this microelement than in the case of supplementation with selenite.

The effect of selenium supplementation on the rumen protozoan population of sheep was demonstrated. Both the total and generic counts of rumen ciliates in sheep fed a diet with basal Se content (70 microg/kg dry matter) were compared to those of animals given feed supplemented with inorganic (disodium selenite) or organic Se (selenized yeast) (310 microg/kg dry matter). The genera of Entodinium, Isotricha, Dasytricha, Ophryoscolex, Diploplastron and Polyplastron occurred in all sheep except for the control, in which Ophryoscolex was not observed. The population of Ophryoscolex caudatus f. tricoronatus was significantly higher in sheep supplemented with organic Se than in animals given inorganic Se (by 160 %). Supplementation of feed with selenized yeast induced significant growth in the Diploplastron population (by 63 %) while no change occurred in sheep given selenite. The populations of Dasytricha ruminantium and Polyplastron multivesiculatum were higher than control in both Se-supplemented groups. The ciliate population of Entodinium spp. was not influenced by Se supplements. Our results suggest a protective effect of Se feed supplementation on the development of some rumen ciliate species in young ruminants.