Why minerals are important for dairy cow performance
No matter how well silage is made, or how high the metabolisable energy of silages and forages are, pasture plus silage diets often do not provide a complete feed for cows. The priority is fully feeding cows to meet their energy and nutrient requirements including protein, starch and fibre.
Supplementation with the right minerals helps achieve and maintain high milk yields and promote healthy reproductive performance.
Minerals are split into two groups: macro minerals and micro minerals (also called trace minerals). In the macro group, magnesium, calcium, sodium and phosphorus often require supplementation. The main micro minerals to consider are cobalt, copper, iodine, selenium and zinc, with biotin and chromium often supplemented too.
As individual feeds vary greatly in quality, perform an extended feed test on pasture and any conserved forages. This analysis will help prevent any deficiencies in the diet and mitigate the likelihood of a lack of minerals compromising animal health, milk production, reproduction and welfare.
Minerals play a fundamental role in getting the cow cycling. Maximise reproductive success by ensuring the cows have adequate mineral supplementation.
Cobalt – Important for glucose synthesis which may affect follicle quality. Supports folic acid metabolism which is important for foetal growth.
Copper – A deficiency has a negative impact on ovary function and conception. Antagonists such as molybdenum may reduce copper absorption.
Iodine – Plays an important role in thyroid hormones and a strong follicle.
Selenium – An antioxidant, selenium supports healthy follicular development and has been shown to reduce the incidence of metritis and ovarian cysts.
Zinc – Performs an integral role in testosterone and oestrogen production as well as being important for uterine health.
Sometimes it is difficult to see visual signs of a deficiency, so take a blood test to sample the herd. Test at least four to six weeks before mating so any issues can be addressed. It is a good idea to consult a veterinarian and/or a nutritionist for further advice and to formulate a tailored programme.
Pasture calcium and magnesium levels are often below milking cow requirements with calcium lost daily in the milk. Calcium supplementation is important to minimise its absorption from the bones of the cow and to support peak milk production. Magnesium plays a crucial role in nerve and muscle function but also in the digestion of feed. Peak milk is a risky time for hypomagnesaemia (low blood magnesium) which can rapidly lead to death. Magnesium must be supplemented daily to minimise risks of a deficiency.
For assistance formulating a mineral supplementation plan for your herd, contact your local PGG Wrightson Technical Field Representative.