F01004: Detection of transgenic protein and DNA in bovine milk and the effect of transgenic substances on nutrient digestion and milk production in dairy cows
Friday 8 October 2004
This research project aims to determine the fate of transgenes in the digestive tract, and to determine whether or not transgenes (and their products) can be detected in animal tissues and milk.
Background
Concern has been expressed over the use of geneticly modified (GM) feeds in dairy cow diets. Whilst studies have not found either transgenic protein or DNA in milk from animals fed GM feeds, no work has been conducted to determine their fate at key stages in the digestive tract of the ruminant. The objective of the project is to measure the effect of ruminant digestion on the fate of transgenic protein and DNA, and the effect of transgenes on nutrient digestion and milk production in dairy cows.
Research Approach
Holstein cows received a total mixed ration of forage and concentrate. The concentrate contained either GM feeds (T1, soybean meal; herbicide tolerant and maize grain; insect protected or non-GM feed ingredients). A switchback experimental design was used with three four-week periods. Immunoassay and polymerase chain reaction (PCR) analyses were used to detect transgenic protein and target DNA (total and transgenic) in diets, rumen fluid, duodenal digesta, faeces, blood and milk. Effects of GM feeds on nutrient digestion, feed intake and milk production were measured. Data provided from these trials allowed a comparison between GM and non-GM diets.
Results and findings
Milk, meat and eggs form an important contribution to the human diet. The production of animal-based foods is highly dependent on imported vegetable protein sources, e.g. soya products. Much of this is imported from the USA. Over 50% of soya-based feed materials from the USA are likely to contain GM components. Vegetable protein is therefore an important ingestion pathway for the incorporation of GM components into the body tissue of an animal.
Concern has been expressed regarding the potential for transgenic protein and/or DNA to be transferred to, and possibly accumulate, in the milk, meat or eggs derived from animals fed GM feeds.
The data from this work are in agreement with earlier studies, which show that fragments or whole t-DNA are not detected in milk derived from animals receiving diets containing GM feed ingredients.
The results of the current study also confirm earlier findings that DNA fragments of rubisco are found in a range of sample types including blood and milk, and evidence is reported that the size of these fragments is larger than previously established.
Dissemination information
Final report is available from the FSA Library and Information centre. To obtain a copy, please contact the Enquiry Desk,
Dr Elsie Widdowson Library and Information Services, Food Standards Agency, tel: 020 7276 8181/8182 or email: library&info@foodstandards.gsi.gov.uk
Contact: For any enquiries concerning this research project, please contact the relevant Programme contact or email science@foodstandards.gsi.gov.uk