Rapeseed meal as a supplementary protein for dairy cows on grass silage-based diet, with the emphasis on the Nordic AAT-PBV feed protein evaluation system

Mikko Tuori

doi:10.23986/afsci.72455

Abstract

The effect of rapeseed meal (RSM) supplementation on the performance of dairy cows on direct cut grass silage based diets was studied in five feeding trials. The proportion of RSM varied from 0% to 33% in the concentrate mixture (the grain was an oat-barley mixture of 1:1). In one experiment the treatments were RSM and soybean meal (SBM), while in another experiment forage was either grass silage or bam dried hay cut at the same maturity. In addition, this was compared to the data of other trials in Finland during the last ten years, in which RSM supplementation had been used. Using this data the response in terms of milk yield to RSM supplementation was estimated. The utilization of protein in milk production was estimated by the Nordic AAT-PBV protein evaluation system. During the experiments (1983-1990) the varieties of turnip rape were changed from high glucosinolate, containing single-zero, to low glucosinolate containing doublezero varieties, while the glucosinolate content was reduced from 40-50 μmoles to 14 μmoles per g of defatted meal. Heat-moisture treatment (™Öpex) further reduced the glucosinolate content by half. By replacing grain with RSM in the concentratemixture with ad libitum silage feeding, the silage intake increased by 0.43 kg per kg increase in RSM on the basis of dry matter (DM) (non significant). The response in increased milk production was 0.77 kg in milk or 0.70 kg in energy corrected milk (ECM) yield (P

Highlights

In Finland milk production accounts for ca. 30% of the gross income from agriculture
In addition to the analyses described under experiments 1 and 2, neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were determined according to Goering and Van Soest (1970)
The crude protein content of silage was fairly high in all experiments, while the crude protein content of rapeseed meal (RSM) ranged from 32.7 to 39.1 per cent

Summary

Introduction

In Finland milk production accounts for ca. 30% of the gross income from agriculture. The proportion of forage in the total feed units averaged 55.4% in 1991 on milk recorded farms, the proportion of silage being 33.1%. Forage was supplemented by grain and protein concentrates, the most important of which were soybean meal and rapeseed meal. In 1991 the combined production ofoilseed meals and oil cakes totalled 190 million kilograms, of which 41% was of rapeseed and 59% of soybean. Rapeseed meal is given mainly to cattle, whereas soybean meal is mainly used in pig and poultry feeds, with only 20-25% used in cattle feed. Replacing a part of the soybean meal in cattle feed with rapeseed meal could increase the domestic cultivation of rape, thereby boosting the national self-sufficiency in cattle feeds. Rapeseed cultivation and production of rapeseed meal could increase in the future ifrapeseed oil were used as a diesel fuel

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