Digestibility of crude protein and fat in feeds for minks with various proportions of poultry shanks, beef meat and fish by-products

The experiment was performed in the Research Institute of Animal Production Nitra. Five male standard minks were used in the experiment at the age of four months. The animals were clinically healthy and examined for plasmocyt osis. The objective of this experiment was to determine the digestibility o f crude protein and fat from feed rations for minks with various proportion s of poultry shanks, as well as the digestibility of these nutrients in the feed. The experiment consisted of three individual stages. The animals wer e fed the control feed mixture which is characterized by the lowest content of poultry shanks -19.6% at the first stage. At the second stage the conte nt of poultry shanks rose to 40.4%, and at the third stage to 50.4% against the original content. Each stage of the experiment consisted of two period s - the preparatory one and the experimental one. The individual periods fo llowed each other immediately during the experiment. The preparatory period lasted seven days, the animals adapted themselves to the new feed ration, and the experiment lasted five days. The animals were fed twice a day - at 9.00 o'clock and 15.00 o'clock. Parameters necessary to calculate the diges tibility coefficients of the studied nutrients from feed rations were recor ded in animals, i.e. feed intake, residues of unconsumed feed and quantity of excrements. Samples to determine the studied parameters were taken twice a day, always one hour before feeding (i.e. at 8.00 o'clock and 14.00 o'cl ock), and they were weighed to the nearest 0.1 g. The excrements were prese rved by freezing at the temperature -17 degreesC. Basic organic chemical an alyses were performed in samples of excrements. Crude protein and fat diges tibility was determined by means of apparent digestibility in feed rations by a direct method, and digestibility of the studied nutrients in poultry s hanks by an indirect method (Schurch, 1969). The digestibility coefficient of the studied nutrients decreases with increasing percentual proportion of poultry shanks in feed rations for minks: for crude protein from 80.75 to 70.35%, and for fats from 90.14 to 84.24%. Significant differences in diges tibility of crude protein and fats on the level of significance P less than or equal to 0.01 were between the control feed ration and experimental fee d rations with the increased proportion of poultry shanks, and between the experimental feed rations as well. The digestibility coefficient in poultry shanks achieved the value 61.73% of crude protein and 78.50% of fats. On t he basis of our results we recommend 40% proportion of poultry shanks in fe ed rations for minks as a maximum for the agricultural practice.