Razgradljivost beljakovin in prebavljivost aminokislin pri prežvekovalcih

Jamšek, Andraž (author), Lavrenčič, Andrej (mentor)

Aminokislinska (AK) sestava absorbiranih beljakovin mora biti čim bolj podobna AK sestavi beljakovin mleka. S tem poskrbimo, da se čim manj dušika izloči v okolje. Mikrobne beljakovine (MB) imajo bolj ugodno AK sestavo od večine krm, zato moramo omogočiti največjo možno sintezo MB. Najbolj limitirajoča AK v MB glede na beljakovine mleka je histidin. AK sestava krme pred razgradnjo se lahko zelo razlikuje od AK sestave nerazgradljivih beljakovin (NRB). Trave in lucerne imajo zelo podobno AK sestavo NRB, ki je relativno ugodna, vendar so te beljakovine slabše prebavljive. V obrokih z veliko koruzne silaže sta lizin in metionin prvi limitirajoči AK. Koruzno zrnje je slab vir beljakovin z neugodno AK sestavo NRB. Koruzni gluten je dober vir beljakovin, vendar so le-te zaradi nizke vsebnosti lizina slabe kakovosti. NRB sojinih tropin so dober vir lizina in histidina, vendar slab vir metionina. Repične tropine so slabši vir esencialnih AK (EAK) od sojinih tropin. Sončnične tropine vsebujejo največ metionina v NRB od vseh opisanih krm. Poleg tega so dober vir histidina, vendar nekoliko slabši vir lizina. Pivske tropine imajo potencialno zelo ugodno AK sestavo NRB, ampak potrebne so bolj podrobne analize. Najbolj limitirajoča AK pri tipičnem obroku za krave molznice v Sloveniji se zdi histidin.

• Language: Slovenian
• Keywords: prehrana živali, prežvekovalci, beljakovine, aminokisline, prebavljivost
• Work type: Bachelor thesis/paper
• Organization: BF - Biotechnical Faculty
• Year: 2021
• PID: 20.500.12556/RUL-131117
• COBISS.SI-ID: 77499651
• Publication date in RUL: 23.09.2021

Secondary language

• Language: English
• Title: The degradability of protein and the digestibility of amino acids in ruminants

Abstract

The amino acid composition (AA) of the absorbed protein should be as similar as possible to the AA composition of milk protein. This will ensure that as little nitrogen as possible is removed into the environment. Microbial protein (MP) has a more favorable AA composition than most feeds, so we need to maximise MP synthesis. The most limiting AA in MP relative to milk protein is histidine. The AA composition of the feed prior degradation may be very different from the AA composition of the ruminally undegradable protein (RUP). Grasses and lucerne have a very similar AA composition of RUP, which is relatively favorable, but these proteins are poorly digested. In diets with lots of maize silage, lysine and methionine are the first limiting AA. Maize grain is a poor protein source with an unfavorable AA composition of RUP. Maize gluten is a good protein source, but of poor quality because of its low lysine content. Soybean meal is a good source of lysine and histidine, but a poor source of methionine. Rapeseed meal is a poorer source of essential AA (EAA) than soybean meal. Sunflower meal contains more methionine in RUP than any other feed described. In addition, it is a good source of histidine, but somewhat poorer source of lysine. Brewer's grains may have a very favorable AA composition of RUP, but a more detailed analysis is needed. The most limiting AA in a typical diet for dairy cows in Slovenia seems to be histidine.

• Keywords: animal nutrition, ruminants, protein, amino acids, digestibility