Comparative evaluation of the protein values of soybean and rapeseed meals by in vivo, in situ and laboratory methods

Publication Type

Contribution to conference

Authors

Südekum, K.-H., D. Nibbe, P. Lebzien, H. Steingaß, H. Spiekers

Year of publication

2003

Published in

Proceedings of the 11th International Rapeseed Congress

Editor

The Royal Veterinary and Agricultural University, Copenhagen, Denmark

Page (from - to)

1241-1243

Conference name

Towards enhanced value of cruciferous oilseed crops by optimal production and use of the high quality seed components

Conference location

Copenhagen, Denmark

Conference date

06.-10.07.2003

Keywords

degradation, Protein, rapeseed meal, rumen, soybean meal

The protein values of 7 soybean (SBM) and 10 rapeseed meals (RSM) were compared. Protein value characteristics (total flow of crude protein [CP] to the duodenum and ruminally undegraded CP [RUP]) were estimated for all 17 meals using the following methods: in situ; in vitro with rumen fluid using either ammonia release and gas production or a modification of the first stage of the Tilley and Terry procedure; in vitro with a protease from Streptomyces griseus; and chemically, using fractionation of the CP based on the Cornell Net Carbohydrate and Protein System. Two samples each of RSM and SBM, which after the first in vitro findings displayed the highest and lowest extent of CP degradation in the rumen, were selected for in vivo experiments on dairy cows with duodenal cannulae in Braunschweig. The CP contents of RSM varied between 37.6 and 42.9% of dry matter and those of SBM from 47.5 to 51.8%. The methods used to estimate the RUP content produced uniform results to the effect that the average RUP content of RSM was higher (35% of CP at 0.05 h-1 ruminal outflow rate) and that of SBM lower (23%) than previously reported. The experiments performed in vivo to determine the total CP flow to the duodenum and the RUP proportions of the four meals yielded hardly plausible values. There was a high compliance with the other methods to the extent that in vivo too, the RSM samples displayed a RUP content of the CP at least as high as that of the SBM samples, the classification of 'higher' and 'lower' RUP contents within RSM and SBM could be confirmed, and the overall protein value confirmed the smaller difference between RSM and SBM derived from the laboratory methods. In conclusion, current commodities of RSM are a better protein feed than previously reported.