Abstract
In order to study the nutritive levels of feedstuffs which are adapted for fattening of the fattening swine in cages, varying levels of TDN of 64.4, 70, and 74 were provided to tested swine while the levels of proteins were kept almost constant (DCP 12.4-12.9), and the results of growths, utilities of feedstuffs, and findings of carcasses were comparatively examined. The results were as described hereunder.
1. With a feedstuff having a TDN of 64.4%, the growths of the fattening swine were fairly retarded, and the findings on the carcasses were fairly poor, demonstrating that the feedstuff was not suitable.
2. With a feedstuff having a TDN of 74.0%, both weight gain and the feed conversion rate were fairly improved, whereas the findings on carcasses were inferior to those with a feedstuff having a TDN of 70% in terms of loin eye area, thickness of back fat and grading of carcasses. Especially to be noted was that those fattened during summer time demonstrated bigger differences in this respect.
3. Even when a feedstuff having a TDN of 74% was provided at the latter half of the fattening stage, the results were inferior to those of a feedstuff with a TDN of 70% in terms of the findings on the carcasses.
4. The results of weight gains depending on the levels of TDN were in proportion to the differences in the TDN levels between the tested classes of feedstuffs.
5. Changes in TDN levels of feedstuffs could not alter the amounts of TDN which were required for a weight gain of 1kg.
6. From these findings, it was assumed that the best possible TDN level for a DCP of 12.4-12.9 would be about 70% (NR4.4), and that there would be no need to change the TDN levels for the earlier and the latter halves of the fattening stage.
