Project number: 61110088
Lead contractor: University of Nottingham
Start and end dates: 14 September 2018 – 30 June 2019
Evidence from other sectors has indicated that minerals are frequently being fed in excess with possible environmental and animal health implications. In a study of 50 dairy farms, Sinclair and Atkins (2014) demonstrated that most farms were feeding excess quantities of minerals. A comparative study from beef finishing systems appears lacking and incomplete.
Aims and Objectives:
The primary aim of this project was to examine mineral intake against requirement, and in particular assess if evidence exists that minerals are being fed in excess, on beef finishing systems and whether a difference exists between cattle that are finished indoors and those that are finished at pasture. It also demonstrated how to undertake a mineral audit on farm and the value of doing so to farmers.
The study required a farm visit to allow collection of feed samples for analysis on a minimum of 14 farms (6 from each type of system – grass finishing versus indoor finishing), but also the completion of a brief questionnaire seeking to explore the decisions taken around ration formulation, particularly with respect to the inclusion of minerals, previous history of any mineral deficiency and current levels of production. Dietary macrominerals assayed included calcium, phosphorus, magnesium, sodium, potassium and sulphur. Microminerals consisted of copper, iron, zinc, molybdenum, selenium and manganese.
Liver and blood samples from 6 animals from each farm were collected immediately post slaughter. Liver mineral analysis consisted of copper, selenium, manganese and cobalt. Blood sample analysis included plasma copper concentration, super oxide dismutase activity, caeruloplasmin activity, plasma selenium concentration, erythrocyte glutathione peroxidase activity, plasma zinc concentration, plasma cobalt concentration, haemoglobin concentration and packed cell volume.
Data was fed back to individual participating farms.
Liver tissue and blood can be collected for analysis in a relatively straightforward manner post slaughter.
- Dietary mineral audits and the analysis of blood and liver samples can be used to identify mineral imbalances on beef finishing farms, which are not uncommon.
- Dietary trace element deficiencies were more likely on farms that finished cattle at pasture. Grazing met macro-mineral requirements, with high potassium contents (over 2%) on most pasture farms.
- Indoor finished cattle had higher dietary intakes of copper and selenium and some farms show evidence of over supplementation.
- On some farms the supply of macro-minerals, particularly calcium, within drinking water is significant and should be included in a mineral audit. For farms on a mains supply details of a basic mineral analysis for individual post codes, or zones, are available from regional water companies.
- Feed manufacturers should be encouraged to provide mineral analyses to their clients containing a full product specification of mineral content beyond that which is provided on the feed label.
- Farmers should seek independent advice about the level of mineral supplementation and the most appropriate means of delivery.
- Mineral analysis has the potential to be used to analyse blood and liver samples in slaughter houses.