Influence of two feed supplements on technological properties of goat's milk / Borut Kolenc, Petra Mohar Lorbeg, Andreja Čanžek Majhenič, Angela Cividini, Mojca Simčič, Primož Treven.
Sažetak

Goat’s daily diet is usually based on grazing, hay and/or feed supplements. Feed supplements are crucial in the diet of high productive goats to achieve their genetic potential and breeders must choose balanced feeding regime to produce large quantities of milk without affecting the technological quality of milk. In the present study, we evaluated the influence of two commercially available feed supplements on goat milk coagulation properties and rheological properties of yoghurts. Goats of the Slovenian Alpine breed (61) were fed with two feed supplements during the 3-year experiment. Feed supplement 1 (FS1) had higher proportions of barley and alfalfa, while feed supplement 2 (FS2) had added premix of minerals and vitamins and had higher proportions of wheat and sunflower meal. Con¬sequently, FS1 had more crude fibres, which is the most probable reason for approximately 15 % higher firmness, consistency and cohesiveness (P<0.05) of yoghurts in FS1 group, compared to the FS2 group. Moreover, the rennet coagulation time (r) was shorter (P<0.05) in the FS1 group, compared to the FS2 group. Curd firmness 30 min after enzyme addition (a30) was also higher in FS1 group although the results were not statistically significant. Taking together, our results indicate that goats fed with FS1 produced milk with better technological properties compared to those fed with FS2, despite the fact that there were no significant differences in chemical composition of milk from each group. We showed that careful selection of feed supplement’s constituents could improve technological properties of goat milk. However, further studies are needed to evaluate the mechanisms of the observed differences.; Hranidba koza na dnevnoj bazi sastoji se od ispaše, sijena i/ili suplemenata. Suplementi su neophodni u hranidbi visokoproduktivnih pasmina koza u svrhu postizanja genetskog potencijala i uzgajivači moraju odabrati režim hranidbe koji osigurava proizvodnju velikih količina mlijeka bez neželjenih promjena u tehnološkoj kvaliteti mlijeka. U ovom istraživanju određivan je utjecaj dva komercijalno dostupna suplementa na sposobnost koagulacije kozjeg mlijeka te na reološka svojstva jogurta od kozjeg mlijeka. Ukupno 61 koza pasmine slovenska alpska koza hranjena je s dva suplementa tijekom tri godine. Prvi suplement (FS1) imao je viši udjel ječma i lucerne, dok je drugi suplement (FS2) imao dodane mineralne tvari i vitamine te više udjele pšenice i suncokretove pogače. Posljedično, FS1 je imao više sirovih vlakana, što je vrlo vjerojatno rezultiralo 15 % većom čvrstoćom, konzistencijom i kohezivnosti (P<0,05) jogurta iz skupine FS1 u odnosu na jogurte iz skupine FS2. K tomu je i vrijeme koagulacije (r) bilo kraće (P<0,05) kod jogurta iz skupine FS1 u usporedbi s jogurtima iz skupine FS2. Čvrstoća gruša 30 min nakon dodatka enzima (a30) također je bila veća u skupini FS1, iako te razlike nisu bile statistički značajne. Uzimajući sve navedeno u obzir, dobiveni rezultati ukazuju kako su koze hranjenje suplementom FS1 proizvodile mlijeko boljih tehnoloških svojstava nego koze hranjene suplementom FS2, unatoč činjenici da nisu utvrđene statistički značajne razlike u kemijskom sastavu mlijeka iz obiju navedenih skupina. Ova studija pokazala je da se pažljivim odabirom suplementa u hranidbi mogu poboljšati tehnološka svojstva kozjeg mlijeka. Međutim, potrebno je provođenje daljnjih istraživanja u svrhu određivanja specifičnih mehanizama koji su doveli do prethodno navedenih razlika.