Requirement of fattening pigs for gross and digestible lysine in feeds with easily and poorly digestible protein.

Abstract

In a feeding trial with 96 barrows and gilts and based on a 2 x 3 experimental design, feeds containing poorly digestible protein sources were compared with feeds containing easily digestible protein sources, at lysine levels of 6.9, 7.5 and 8.1 g/kg. In the liveweight range from 30 to 70 kg daily rate of gain on both types of diet was higher with more lysine. From 30 to 110 kg, rate of gain was proportional to lysine content only for the diet with poorly digestible protein. Requirement for gross lysine seemed to be 7.0 to 7.5 g/kg for feed with easily digestible protein and at least 7.9 g/kg for that with poorly digestible protein. In a digestibility trial with pigs weighing about 30 kg, apparent digestibility of feeds with lowest and highest lysine levels was determined. Digestibility coefficient of crude protein was 7 to 12 units lower than figures given in the CVB table (Central Bureau on Livestock Feeding in the Netherlands). Digestibility coefficients for lysine were only marginally lower than for crude protein. On the basis of digestibility coefficients determined for lysine, it was possible to calculate the requirement for digestible lysine for the pigs used in the feeding trial. Results showed 5.3 to 5.7 g/kg for the diet containing easily digestible protein, and at least 5.6 g/kg for that with poorly digestible protein. (Abstract retrieved from CAB Abstracts by CABI’s permission)