Kvasac u ishrani monogastričnih životinja

Abstract

Kvasac predstavlja nutritivno vredno hranivo koje je bogat izvor proteina visoke biološke vrednosti, kompleksa vitamina B, minerala u tragovima i mnogih drugih korisnih materija. Uglavnom je u upotrebi stočni i pivski kvasac. Suvi stočni kvasac dobija se gajenjem gljivica kvasca (Torula utilisili Saccharomyces species) na različitim podlogama (melasa, celuloza). Ovakav kvasac sadrži 40-60% sirovih proteina visoke biološke vrednosti i svarljivosti. Od esencijalnih aminokiselina bogat je lizinom (3,47%), a sumpornih aminokiselina ima samo 1,14%, što ga razlikuje od animalnih i nekih biljnih proteinskih hraniva. Najbogatiji je izvor vitamina B kompleksa od svih hraniva. Energetska vrednost suvog stočnog kvasca je 10,1 MJ/kg hrane. Obično se koristi u ishrani svinja i živine u količini od 1-7% u smeši. Suvi pivski kvasac se dobija sušenjem svežeg pivskog kvasca nakon filtracije pivske čorbe fermentisane kvaščevim gljivicama (Saccharomyces species). Ovakav kvasac sadrži 40-50% proteina visoke biološke vrednosti i svarljivosti. Energetska vrednost suvog pivskog kvasca je 7,7 MJ/kg hrane. Pored ovoga, u hranu za životinje mogu se dodati i žive ćelije kvasca (Saccharomices cerevisiae) (Live Yeast Cells-LYC) i njihov značaj je višestruk. Žive ćelije kvasca spadaju u grupu potentnih mikroorganizama koji se koriste kao dodatak u hrani za životinje i predstavljaju alternativu za antibiotike koji su se donedavno učestalo koristili u ishrani životinja kao stimulatori rasta. Za ulogu kvasca kao promotera rasta najzaslužniji je mananoligosaharid, izolovan iz spoljašnjeg ćelijskog zida kvasca (S. cerevisiae). Dokazano je da se suplementacijom obroka celim kvascem ili ćelijskim zidom kvasca u količini 1,0- 1,5 g/kg mogu poboljšati performanse rasta i prirasta mesa kod brojlera. Žive ćelije kvasca poseduju velike količine polisaharida, zajedno sa manozom i glukanima, a poznata je njihova uloga i u modulaciji imunološkog odgovora organizma u interakciji sa različitim imunokompetentnim ćelijama. Pored toga, dodavanje živog kvasca u hranu životinja, može uticati na poboljšanje varenja i apsorpciju hranljivih materija iz intestinalnog trakta i to: modulacijom strukture creva, inhibicijom patogenih bakterija i smanjenjem pH vrednosti u crevima (što dovodi do stvaranja organskih kiselina koje deluju kao zakišeljivači).

Yeast is a nutritionally valuable feed that is a rich source of proteins of high biological value, vitamin B complex, trace minerals and many other useful substances. Livestock and brewer's yeast are mainly used. Dry yeast as feed is obtained by growing yeast fungi (Torula utilis or Saccharomyces species) on different substrates (molasses, cellulose). This type of yeast contains 40-60% raw proteins of high biological value and digestibility. It is rich in lysine (3.47%) of essential amino acids, and only 1.14% of sulfur amino acids, which distinguishes it from animal and some vegetable protein nutrients. It is the richest source of vitamin B complex of all nutrients. The energy value of dry animal yeast is 10.1 MJ/kg of feed. It is usually used in the nutrition of pigs and poultry in the amount of 1-7% in the mixture. Dry brewer's yeast is obtained by drying fresh brewer's yeast after filtering beer broth fermented with yeast fungi (Saccharomyces species). This type of yeast contains 40-50% protein of high biological value and digestibility. The energy value of dry brewer's yeast is 7.7 MJ/kg. In addition to this, live yeast cells (Saccharomyces cerevisiae) (Live Yeast Cells-LYC) can be added to animal feed and their importance is multiple. Live yeast cells belong to a group of potent microorganisms that are used as an additive in animal feed and represent an alternative to antibiotics, which until recently were often used in animal nutrition as growth stimulators. The most important role of yeast as a growth promoter is mannanoligosaccharide, isolated from the outer cell wall of yeast (S. cerevisiae). It has been proven that supplementing the meal with whole yeast or yeast cell wall in the amount of 1.0-1.5 g/kg can improve growth and meat gain performance in broilers. Living yeast cells possess large amounts of polysaccharides, together with mannose and glucans, and their role in modulating the immune response of the organism in interaction with various immunocompetent cells is known. In addition, the addition of live yeast in feed can improve digestion and absorption of nutrients from the intestinal tract by: modulating the structure of the intestine, inhibiting pathogenic bacteria and reducing the pH value in the intestine (which leads to the creation of organic acids that act as acidifiers).