The use of rapeseed, rapeseed cake and rapeseed oil in lamb fattening

In a feeding experiment with lambs the following questions were to be answered: 1. Reaction of replacement of soybean meal in concentrates by rapeseed cake on the feed intake, fattening and carcass yield. 2. In case of a higher fat content in concentrates (i.e. rapeseed oil), will there be a difference between cell bound and free oil. A total of forty weaned tup lambs (genotype: Merino Sheep, Blackhead Mutton Sheep x Merino Sheep) were fattened up to an average finishing weight of 49kg under conditions of a high feeding intensity. Four groups were built (n = 10) each receiving four different mixed concentrates. The control group was fed conventional mixed concentrates on the basis of coarse meal of cereal-dried sugar beet pulp-soybean. The mixture for th testgroup 1 contained 10% rapeseed. In testgroup 2 soybean meal was replaced by 34% rapeseed cake. Test-group 3 was given mixed concentrates with 4% rapeseed oil. All mixtures were composed in an isoenergetic and isonitrogenous way. The three mixtures for the testgroups contained a higher content of crude fat and crude fiber than the control mixture. The fat content of the test mixtures had the same level. All four feed compounds were fed without problems of acceptance. As to the average feed intake there was only a negligible difference between the groups. On an average the lambs had a weight gain of 329 g a day. Comparing the control group, the test groups 1 und 3 with test group 2 as for the daily weight gains the former were nearly equal whereas the latter declined with 298 g significantly. The difference to the other groups was statistically secured. The ratio of feed intake to weight gain with rape cake was also more unfavourable. In this group there was also a decline of the slaughter value below the average. Beside a lower slaughter weight, the carcass weight was the lowest as well. Considering the reasons for this lower performance two factors are discussed: The higher portion of indigestible crude fiber in the rapeseed cake mixtures and the high intake of glucosinolate. In respect to the composition of fatty acid in the fat tissue there was practically no difference between the three test groups. This accordance let presume that the process of digestion in the:rumens took place in a parallel way. There was no difference between feeding cell bound oil or free oil.