Deficiency and excessive levels of selenium in poultry

Abstract

Deficiencies of selenium in diet in poultry (below 0,15 mg/kg) lead to poor increasing, disturbance of health state and decreasing of reproductive capacities. The most frequent diseases caused by deficit of selenium are: exudative diathesis, pancreatic fibrosis and muscular dystrophy. Surplus of selenium can cause acute or chronic sclenosis. Acute selenosis is appeared when poultry take high levels of selenium in short time period. It is manifested by rapid breathing, vomiting, diarrhea, tetanus spasms and deaths occur due to suffocation. Chronic selenosis is appeared when poultry take diet containing more than 5 and less then 40 mg Se/kg in longer time period. It is shown by increase of concentration of Se in blood and muscles, reducing growth and increasing mortality at levels higher than 15 mg Se/kg diet. Level of selenoenzyme OSH-Px is not linear dependence to level above necessary, the activities of this enzyme show the effect of plateau, so that more selenium does not to further increasing of its activity.

Deficit selena u hrani kod živine (ispod 0,15 mg/kg) dovodi do slabijeg prirasta, poremećaja zdravstvenog stanja i smanjenja reproduktivnih sposobnosti. Najčešća oboljenja prouzrokovana deficitom selena su: eksudativna dijateza, fibroza pankreasa i mišićna distrofija. Suficit selena kod živine može da izazove akutnu ili kroničnu selenozu. Akutna selenoza se javlja kada živina u kratkom vremenskom intervalu unese visoke nivoe selena. Ona se manifestuje ubrzanim disanjem, povraćanjem, dijareom, tetanusnim grčevima, a uginuća nastaju usled ugušenja. Hronična selenoza nastaje kada živina duži vremenski period unosi hranu koja sadrži više od 5 a manje od 40 mg Se/kg. Ona se manifestuje porastom Se u krvi i mišićima, smanjenim prirastom i povećanim mortalitetom pri nivoima višim od 15 mg Se/kg hrane. Nivo selenoenzima GSH-Px nije u linearnoj zavisnosti od nivoa selena u hrani. Pri povećanju nivoa iznad potrebnih, aktivnost ovog enzima pokazuje efekat platoa, tako da viši sadržaji selena ne dovode do daljeg povećanja njegove aktivnosti.