Conditions for the lactic acid fermentation of fish offal were evaluated regarding the effect of substrate concentration (2, 5 and 10% dextrose), preacidification with lactic acid (initial pH of 6.8, to 6.5 or 6.0), and inoculum size of Lactobacillus plantarum (107 , 108 and 109 colony forming units (cfu)/g). pH and lactic acid production were monitored during a two-week storage period. A small-scale silo for fermenting fish offal was also constructed, and measurement of redox potential was evaluated as a means to estimate bacterial growth conditions. The most favourable conditions for fermentation, manifested by a low and stable pH and high lactic acid production, were achieved with an inoculum size of 108 cfu/g and 5% dextrose. Preacidification did not affect final pH. Redox potential was shown to give a reliable estimate of growth conditions for bacteria under anaerobic conditions by rapidly falling to below -550mV in silage with a high lactic acid concentration.
Effects of reduced protein content and content of some essential amino acids on skin length and skin quality was studied in the growth and furring period in Black and Brown/Glow mink in 2010 and 2011. In 2010 five groups of each 276 male and female Brown/Glow mink kits were used. In 2011 five groups of each 155 male and female Black mink and three groups of each 155 Brown/ Glow male and female mink were used. The mink were feed diets containing varied protein and amino acids from mid-July to pelting. Results showed that reduced protein content down to 21.5% of the metabolizable energy (MEp) from July to pelting or from mid-August to pelting and a changed amino acid profile cannot be used, since the skin length is shorter, the pelt quality is poorer and there is an increased risk of fatty liver. 28 MEp from mid-July to mid-August and thereafter 24 MEp resulted in the longest skins but a little reduced pelt quality in both mink types, most likely due to low protein content in July in the period where plant for wool and hairs are formed, since the skins were generally flatter and less heavy/voluminous.