Molybdenum plays an important role in detoxification, preventing nitrosamine formation. Lamb, lentils, squash, green beans and carrots may be rich in molybdenum. Molybdenum is part of the enzyme xanthine oxidase. Symptoms of deficiency include weight loss, emaciation and diarrhoea. Molybdenum is included in some stock food supplements. The plant processes involving conversion of ammonium nitrogen into protein take place in the roots. This always involves energy, so the roots signal the above-ground plant to increase photosynthesis and thereby boost glucose delivery. This is one of the reasons for the greening effect associated with application of ammonium fertilisers. Nitrates awaiting conversion in the roots move into the leaf where they are converted to amines, amino acids and protein. This energy draining process requires an enzyme called the nitrate reductase enzyme. This enzyme is dependent upon sulfur and, most importantly, Mo. If you have ignored molybdenum, the nitrates remain unconverted in the leaf, the insects receive a calling card and consumers get to eat food filled with toxic nitrates.
Low level molybdenum toxicity can seriously affect fertility. Molybdenum needs to be at 1ppm in the soil. We have seen dozens of soil tests where it is around 6-8 ppm. If that is the case, get the copper up pronto. I have only recommended molybdenum to be applied to one crop I have tested. That was citrus and the grower pointed out the visible symptoms that were later confirmed by the PAL soil test. The Mo level was 0.95ppm, but those deficiency symptoms were quite visible. Required at 1-2 ppm in soil. Rarely deficient.
Dead and dying calves
Many thanks for the extra data very interesting soils, so low in magnesium and the high molybdenum is a very big issue.
The molybdenum if coming through in the plant tissues will antagonise copper severely, and cause a severe copper deficiency.
Copper is required to switch on iron, and iron is already low on theses soils and may also be in the plants.
Iron is required to carry oxygen around the body in the red blood cells, without iron the animal will become anaemic, silent heats will occur, they will show lack of vigour, and ill thrift, they will have pale eyelids, gums and inner vulvas.
The low copper can result in falling disease, sudden death with seemingly no symptoms, because the blood vessels have collapsed, and heart attack has occurred, side wall cracks in hooves and overlong toes will be seen, the animals will have a roan colour to their coat, and be hairy. Low magnesium lets potassium dominate which can cause poor microbial balance in the rumen and cause a sodium, potassium imbalance so bloat is more likely as is grass tetany and milk fever and osteoporosis.
Magnesium is also a calming mineral so animal behaviour may also be erratic.
Any tissue tests on the paddocks they may have would be very useful additional information.
Phosphate is obviously not the limiting factor. Magnesium is a phosphorus synergist carrying P into the plant. If there is not enough P getting into the plant in high P soils i.e. 500kg P2O5, then there is inadequate microbial activity in the soil and inadequate magnesium arriving at the plant.
The Thiamin disease you referred to is a Vitamin B1 deficiency.
This is induced by high sulphur and or moly and very low copper levels in the feed the animal is eating.
Symptoms are blindness, head pressing (tipping the head to one side) and circling before finally sitting down on their haunches and dying.
Thiamin can be injected, but is only good at keeping the animal alive short term.
The key is to supplement with copper and B group vitamins.
Kelp is very good for the supply of all B vitamins and maybe even better is yeast, and copper can be injected or supplied in a rumen bolus or even as a lick of copper sulphate. These animals will not gain weight or be productive until the problem is addressed.
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