Protein requirements of Arctic charr / Próteinþörf bleikju
Fimm mismunandi fóðurgerðir með próteininnihaldi frá (29) 30 – 40% voru gefnar tveim stærðarhópum (100 gr. og 600 gr.) bæði í fersku og söltu vatni. Áhrif mismunandi fóðra voru metin út frá áhrifum þeirra á meltanleika, þyngdarþróun, dagvaxtar (SGR), fóðurnýtingar (FCR), efnasamsetningu flaka (í stærri fiskinum) og skynmat. Lokaþungi og dagvöxtur var lægstur hjá þeim fiskum sem fengu fóður með lægstu próteini, en engin áhrif fundust af próteini, umfram 37% í fóðri, á lokaþunga og SGR. Lágmarksþarfir fyrir prótein til vaxtar liggja því á milli 33% og 38% í fóðrinu. Ekki var um að ræða neinn verulegan mun á fóðursvörun milli stærðarhópa, jafnvel að áhrifin af lækkuðu próteini væru meiri hjá stærri fiskinum. Ekki var heldur hægt að sjá ein afgerandi áhrif af seltu á próteinþörfina. Próteininnihald í fóðri hafði ekki heldur nein afgerandi áhrif á flakasamsetningu eða skynmat á afurðum.
Four (five) different diets with protein varying from (29) 30 – 41% were fed ad libitum to two size groups of Arctic charr (100 gram and 600gram) in fresh‐ as well as seawater. The effect of the different diets was evaluated by digestibility, weight development, SGR, FCR, chemical composition of filet (in the bigger size groups) and sensory evaluation. The lowest final weights and SGR were found when fed the diets with lowest protein but here was no effect final weight and final weight between 38% and 41% protein in the diet, indicating that the minimum need for protein is between 33 and 38% protein in the diet. The same trend was shown in both size groups but the effect was more pronounced in the bigger fish than in the smaller fish. The results regarding size and growth were also the same in fresh‐ and seawater. The protein content in the diet did not have any marked effect on either chemical composition of filets or the sensory quality of the product.