The dos and don’ts of drought feeding

By Marinda Louw Coetzee | 11 September 2024 | 5:30 am

South African farmers are no strangers to droughts, but livestock producers often fail to plan ahead for them, leading to high costs from animal loss and feeding. Prof HO de Waal, affiliated professor in the University of the Free State’s Department of Animal, Wildlife and Grassland Sciences, spoke to Marinda Louw Coetzee about implementing effective drought feeding strategies for ruminants.

During periods of drought there is a scarcity of plant material for grazing, and what remains is often trampled by livestock. Photo: FW Archive

What is drought, how does it manifest, and what are the effects?

A drought is a prolonged period of time during which there is no rainfall. Plant material becomes sparse, and what there is often gets trampled by the hooves of too many livestock.

As the drought progresses, livestock increasingly spend energy in search of grazing material. The net effect is an insufficient daily ingestion of nutrients to meet the animals’ maintenance requirements, causing a progressive loss of body condition.

Should farmers introduce additional feed during a drought?

The decision to give additional drought feed must be considered wisely, timely, and judiciously. Starting too early will increase feed costs unnecessarily, but delaying it for too long may also be very costly in the long run.

How can farmers avoid feed stress in their animals?

Appropriate planning and timing will prevent nutritional stress in ruminant livestock. A ruminant’s complex digestive system, specifically the microbial population (bacteria, protozoa

and fungi) in its reticulorumen, needs a gradual changeover and adaptation between different diets.

For example, when grazing livestock are moved from the veld to a feedlot, it takes 10 to 14 days for the different microbes to adapt to the new feeding regime. This is necessary because feedlot diets contain more carbohydrates that easily ferment in the reticulorumen, more lipids, and less fibre.

Time allows the amylolytic (starch fermenting) microbes to increase, while the cellulolytic (fibre/cellulose fermenting) microbial population will decrease.

Ruminants coexist in a unique symbiotic system with microbes in the first part of the digestive tract and require a minimal yet adequate amount of fibre in the diet to function optimally.

The complex ‘stomach’ of ruminants comprises four compartments, namely the reticulum (ruitjiespens), rumen (grootpens), omasum (blaarpens), and abomasum or glandular stomach (melkpens).

Mechanical digestion by the molar teeth during rumination is followed in the reticulorumen by extensive microbial fermentation (digestion). These processes rely on the different enzymes provided by the microbes. Once food particles have been sufficiently reduced in size, they move further through the omasum to the abomasum.

The first enzymes secreted by the host ruminant animal are only secreted in the abomasum.

It is important to note that this microbial activity provides a significant portion of the animal’s protein requirement. Additionally, non-protein nitrogen (NPN) sources, such as urea, can be fed to ruminants. They allow microbial protein synthesis, which may meet the host animal’s maintenance requirements.

When should farmers start planning their feeding strategies for droughts?

At least one year in advance; that is, during the previous growing season. Assess the feed requirement of the number of livestock and their production phases in relation to the available feed resources. If a shortfall in available feed is foreseen, the number of livestock must be adjusted downwards and well in advance.

Look at your animals and decide which ones will be fit and strong enough to endure another pregnancy and suckling period on the farm. The focus must be on the reproducing females and the suckling young at foot. This is the core herd or flock for continuing production.

Livestock that are less productive can be auctioned or moved to another feed source, such as a feedlot. This will help ensure sufficient feed for a more robust core reproducing herd or flock to produce strong offspring during the next breeding season.

Good drought planning involves ensuring your livestock have enough pasture without surpassing the land‘s long-term grazing capacity.

How do I prepare my animals for a drought?

Prepare your herd according to its breeding cycle. In preparation for the next calving season, inspect cows’ teeth, udders and teats. If the teeth on the front of the lower jaws (mandibles) are worn and cannot last another 18 months (the normal period for gestation and lactation), these cows must be removed.

It is prudent to synchronise the lactation phase of cows with the active growth or production of grazing. Thus, cows/heifers are put to the bulls in mid-December to calve the following year from the beginning of October. Correspondingly, the calves are weaned annually in May/ June at the age of seven to eight months.

Sheep and goats have shorter gestation periods of five months, and they usually lamb or kid in spring or autumn. Again, available crop residues and planted feed sources, such as small grain cereals and lucerne, may complement the fodder flow and thus determine the optimal lambing or kidding season.

How do I prepare grazing and feed availability for possible drought?

Judicious planning means creating sufficient available veld for the number of livestock on the farm, which must not exceed the long-term grazing capacity of the veld.

It should also account for ample grazing and stored standing veld hay to bridge the gap at the end of the winter. Other feed sources, such as crop residues and planted pastures, will assist in planning the more appropriate fodder flow for optimum livestock production.

Available crop residues, such as maize, baled hay, or planted pastures, such as Smutsfinger, may supplement the feed required for livestock.

Any advice on processed feed?

Processed feed is expensive. Therefore, it is important to plan how to feed animals, even dairy cows. This is called feed trough management. Feed should be provided in appropriate containers, such as drums, tyres, hay racks and troughs.

Do not place feed directly on the ground where it will be trampled and soiled. Provide enough trough space to prevent more dominant animals from creating too much competition at the peril of the weaker or less dominant animals.

How do licks and other supplements help during droughts?

Supplementary feed and licks have a precise role in ruminant nutrition. Ruminants that graze on veld may experience deficiencies in specific nutrients. Salt, phosphorous and a range of other mineral elements may be included in basic livestock licks. The concentrated nutrients provided in licks are intended to be consumed in small quantities.

During late autumn and winter, dormant veld grass species may not contain adequate levels of protein. If there is insufficient plant material on the veld, it is futile to provide additional protein, especially NPN in the form of urea.

Plant proteins (oil cake meal) or urea may be included in so-called winter licks to supplement the low nitrogen content of the veld grass and stimulate microbial activity. Consult a professional animal nutritionist for advice on appropriate supplementary feeding.