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Evaluation of heat-treated lupins, beans and rapeseed meal as protein sources for dairy cows

HGCA PROJECT REPORT OS45

Evaluation of heat-treated lupins, beans and rapeseed meal as protein sources for dairy cows

by

A Moss
ADAS FENS, Alcester Road, Stratford upon Avon, Warwickshire CV37 9RQ

R Allison, A Stroud and C Collins
ADAS Bridgets, Martyr Worthy, Winchester, Hampshire SO21 1AP

August 2000

Abstract

The UK ruminant feed industry is heavily reliant on fishmeal and soyabean meal as sources of high quality protein within rations. However, there is increasing concern over the sustainability of fish stocks and supplies of imported soyabean meal. There are several oil and protein crops which will grow under UK conditions including oilseed rape, sweet white lupins and beans. However, their protein tends to be more degradable in the rumen of dairy cows (i.e. lower quality protein). Previous work funded by the Milk Development Council and MAFF conducted at ADAS Bridgets has identified several issues limiting higher inclusion rates of home-grown proteins within the ration of dairy cows. For UK grown proteins to be attractive alternatives to fishmeal or soyabean meal, processing strategies such as heating which improve protein quality (by reducing degradability in the rumen) must be developed.

Within this project, the optimum duration and temperature of the heat treatment method to optimise rumen degradability of the protein for sweet white lupins, beans and rapeseed meal was determined. This treatment method was then scaled up to produce 3 tonnes of lupins and 6 tonnes of both beans and rapeseed meal. In a 10 week feeding study, 60 high yielding Holstein cows in early lactation, yielding in excess of 30 kg/day were fed complete diets based on high quality grass silage which contained one of five different combinations of protein sources. These included fishmeal + soyabean meal (Control), heat treated rapeseed meal (2.7 kg/cow/day), heat treated sweet white lupins (3.0 kg/cow/day), heat treated beans (4.0 kg/cow/day) or a combination of the heat treated home-grown proteins.

The optimum heat treatment was found to be the same for rapeseed meal, sweet white lupins and beans; the protein being heated at 120ºC for 35 minutes.

The results of this study demonstrate that fish meal and soyabean meal can be replaced with either heat treated rapeseed meal, heat treated beans or a combination of heat treated proteins without any reduction in milk yield or quality. The results also demonstrate that heat treated rapeseed meal and beans can be successfully included in the ration at up 32% and 34% respectively of the concentrate, without any adverse effect on milk quality. There was no evidence that tannins, known to be present in beans, had any adverse effect on protein digestibility. Additionally, feeding heat treated lupins had no adverse effect on milk yield, milk fat content or milk lactose content when replacing soyabean meal/fishmeal in a ration, although, both milk protein and casein N content were reduced by 5%.

Margin over purchased feed cost was similar for cows fed rations based on fish and soyabean meal or heat treated rapeseed meal when soyabean meal, fish meal and heat treated rapeseed meal were valued at £125, £381 and £143/tonne respectively. Replacing fish and soyabean meal with heat treated lupins (£180/tonne), beans (£134/tonne) or a combination of heat treated home-grown proteins (£148/tonne) resulted in lower margins due to the higher feed costs and reduced milk sales for lupins.

In order to exploit the considerable potential for home grown proteins, it is essential that less expensive techniques which are equally effective in terms of protein protection are developed. This would ensure far greater use of home grown proteins. An increase of 1% in the average inclusion rate in UK ruminant compound feeds of home-grown proteins would demand an extra 40,000 tonnes/year, equivalent to 23,000 ha of rapeseed or 15,000 ha of beans.

HGCA Project Number: 2156
Price: £4.50

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