Digestibility by mink and storage stability of feedstuffs made from raw ground, acid-treated or fermented dogfish (Squalus acanthias)

Dogfish was evaluated in a 3 x 4 factorial design experiment conducted to d etermine digestibility coefficients (DC) of dry matter (DM), crude protein (CP), crude fat (CF), gross energy (GE) and amino acids (AA) in raw ground dogfish (RGD), acid (ASD) and fermented (FSD) dogfish silages for mink. The ASD was prepared with the addition of 2.5% (wt:wt) formic acid (conc. 85%) and 200 mg kg(-1) antioxidant (ethoxyquin) to the raw ground fish. The FSD was produced with the addition of the commercial biopreservative Marisil(R ), (Finn Sugar) (1%) and extruded wheat (15%) to the raw ground fish. In th e digestibility trial, consisting of three, 11-d periods, each having a 6-d adjustment followed by a 5-d collection, 12 mature standard type mink were confined to metabolism cages. Using the total collection (TC) method, wher e graded levels (0, 15, 30 and 45%) of the test feedstuff were substituted into a basal diet, an extrapolation using regression analysis was done to e stimate digestibility of each test feedstuff. The AD of DM, CP, CF and GE w as RGD: 81.8, 92.2, 96.2 and 89.6%; ASD: 87.1, 92.6, 100.0 and 93.2%; FSD: 86.0, 93.3, 98.1 and 90.4%, respectively. The AD of AAs was generally highe st in the fermented dogfish feedstuff. A quality evaluation of the silages was conducted in a completely randomized design with four replications (two replications for AAs), to determine storage stability of the silages, on 1 0 different sampling days (days 1, 3, 6, 9, 15, 30, 90, 180, 270 and 360), (three sampling days for AAs) post-manufacture. The ASD was stable up to 18 0 d, after this storage time it underwent increases in pH and total volatil e nitrogen (TVN) and decreases in N and AA content. The preservation of dog fish with a fermentation method (FSD) was judged to be unsuccessful with th is feedstuff having a high initial pH (6.4) and large increases in TVN cont ent early in storage. It was concluded that feedstuffs made from dogfish wo uld provide a source of highly digestible nutrients for mink; however, more research is required before a fermented dogfish feedstuff can be incorpora ted into practical mink diets.