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The first good rains of the season always bring relief to livestock producers. The veld transforms into a green carpet almost overnight, and animals immediately respond to the fresh growth. This lush, actively growing grazing is highly palatable, rich in protein and energy, and supports excellent livestock performance. Feed intake increases, and producers expect rapid improvements in growth rates and body condition.
Experienced livestock producers know, however, that green grazing also presents challenges. Young, succulent plants are high in moisture, which can dilute nutrient intake despite their palatability. At the same time, fibre levels during the earliest growth stages are often too low to support optimal rumen function.
Animal nutrition
Increased feed intake following good rains also raises the animal’s demand for certain minerals, particularly phosphorus and essential trace elements. The period of rapid growth is also often when mineral deficiencies are most likely to develop.
According to Dr Francois van de Vyver, marketing director at Kemin South Africa, veld types differ across the country, but the macro- and micromineral profile of green grazing generally follows the same pattern. Young animals thrive on nutritious vegetation, yet they are also the group that develops deficiencies quickest.
This is not a new observation, he notes. As early as 1924, Theiler, Green and Du Toit identified phosphorus deficiency, or aphosphorosis, as one of the greatest limitations to cattle production on veld. Their work laid the foundation for mineral supplementation practices that remain relevant today.
Deficiencies in green pasture
“While phosphorus is the most important deficiency associated with green grazing, it is not the only one. Lush vegetation can mask borderline trace element deficiencies until animal performance stagnates or reproductive problems start to appear. Because nutrient levels rise sharply after rain, the animal’s mineral requirements increase in parallel. If supplementation is inadequate, deficiencies can develop rapidly.”
Mineral supplementation is therefore not optional, but part of a strategic management tool that unlocks green grazing’s full value.
A well-balanced phosphate or production lick during the green season is the most practical way to address macro- and micromineral deficiencies. These licks primarily supply phosphate together with carefully formulated levels of trace elements such as manganese, copper, cobalt, zinc, selenium, iodine, and iron.
Phosphorus plays a central role in energy metabolism, bone development, fertility, and milk production. When supplied at the correct levels, the utilisation of green grazing improves markedly. Producers commonly report improved body condition, higher weaning weights, stronger oestrus activity, better conception rates, and faster growth in young animals. On phosphorus-deficient veld, herds respond noticeably within a single season.
Key trace elements
Although each mineral performs a distinct physiological function, all contribute to growth, immunity, and reproduction – the pillars of profitable livestock production. The following trace elements are especially important during the green season, even before grazing reaches maturity.
- Manganese: Manganese is essential for bone development and reproduction. Deficiencies are associated with irregular oestrus, lower conception rates, and poor growth in young animals. Severe deficiencies may also negatively affect bull libido and spermatogenesis.
- Copper: Copper deficiency can result in prenatal losses and weak calves. It also plays an important role in oestrus expression, immune function, and pigmentation. In certain soil types, early rains can increase the availability of antagonists such as molybdenum and sulphur, further limiting copper absorption and increasing the need for supplementation.
- Cobalt: Rumen microbes require cobalt to synthesise vitamin B12, an essential component of energy metabolism. In cobalt-deficient areas, animals may lose condition despite abundant grazing because rumen function is compromised. Supplementation improves appetite, rumen efficiency, and performance.
- Zinc: Zinc is vital for hoof integrity, skin health, and immune function. In males, it supports spermatogenesis, contributing to improved semen quality and libido. Young, growing animals also have elevated zinc requirements for tissue development.
- Selenium: Deficiency is associated with muscular dystrophy and poor calf vigour, immunity, and fertility. Including selenium in phosphate or production licks can help prevent premature births and improve calf survival.
- Iodine and iron: These elements support growth and the development of the ruminant.
Practical application
Dr Van de Vyver says well-formulated green-season mineral licks are a cost-effective safeguard against production losses. The aim is not to correct deficiencies after they occur, but to prevent them by supplying minerals in the correct proportions when demand is highest. Animals should have continuous access to the lick, and intake should be monitored regularly to ensure consumption is within recommended levels.
“By investing in balanced mineral supplementation when the veld is at its best, producers can fully utilise the growth potential of lush early-season grazing. The result is healthier animals, improved reproduction, faster calf growth, and a more resilient and profitable livestock enterprise.” – Izak Hofmeyr, Stockfarm
Contact Dr Francois van de Vyver at 083 419 4562 for more information.
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