Written by PJ, from VELD FIRST, KAROO DIREK, DIE VEEPOS and KAROO-KALAHARI VEEVOER & LOGISTIEK in August 2026.
Normal, gradual seasonal transitions to longer daylight hours, referred to as the photoperiod, and warmer temperatures, such as the shift from winter to spring and summer, act as critical evolutionary and developmental triggers for ruminants.
Rather than causing sudden distress, these natural shifts safely re-align the animal’s reproductive cycles, metabolic rates, and grazing behaviours.
Direct Effects on Ruminants
Reduced feed intake
- Animals eat less food to lower internal body heat produced by digestion.
- Slower digestion leads to less energy and fewer nutrients available for the body.
Lower production and growth
- Dairy cows produce less milk with lower fat and protein content.
- Meat-producing animals gain weight much more slowly.
Decreased reproduction
- Higher temperatures can disrupt hormone balances in females and can lower conception rates.
- Semen quality and sex drive drop in males.
Lowered immunity
- Excessive heat will raise cortisol levels in the blood.
- Lowered immunity makes animals more vulnerable to diseases and parasites.
Behavioural changes
- Animals spend more time standing, panting, seeking water and shade instead of resting or grazing.
- Water consumption increases sharply to help the body cool down through evaporation.
How can livestock farmers take advantage of normal seasonal changes from winter to summer conditions?
Farmers can strategically align their herd and flock management with increasing daylight and rising temperatures to boost productivity, cut feed costs, and keep animals comfortable.
1. Implement strategic grazing and veldt management
The shift to spring and summer triggers a surge in veldt and pasture growth. Farmers can maximize this high-quality, low-cost forage by adapting their grazing strategies.
- Adopt rotational grazing: move livestock through grazing camps or paddocks more regularly. This allows grazed areas time to rest and regrow, maximizing forage yield per hectare during peak growing months.
- Match stocking rates to growth: increase herd sizes or graze more intensively during the spring flush to utilize rapid grass growth before it becomes mature, woody, and less nutritious.
- Shift grazing periods: if you follow an intensive farming model, turn animals out to pasture during the cooler dawn and dusk hours. This aligns with their natural seasonal instinct to graze when temperatures are comfortable, preserving pasture and preventing midday trampling.
2. Leverage longer days with photoperiod management
Longer daylight hours naturally stimulate growth and milk production hormones. Farmers can manipulate or capitalize on this biological response.
- Use supplemental lighting: in dairy and battery setups, maintain a 16-hour light and 8-hour dark cycle using energy-efficient barn lights. This tactic mimics peak summer daylight year-round, reliably boosting production by up to 10%.
- Optimize breeding windows: plan breeding schedules so that offspring are born when natural resources are peaking. For sheep and goats (short-day breeders), utilize the natural summer anestrus period to systematically prepare ewes for autumn breeding using flushing diets (increasing feed just before breeding to boost ovulation).
3. Adjust nutrition and feeding strategies
As temperatures rise, a ruminant’s nutritional needs shift away from winter maintenance (burning energy for heat) toward production.
- Lower fibre, increase energy density: digesting fibre produces significant internal body heat. Gradually transition the herd to high-quality, highly digestible summer forages. Adding high-energy supplements helps maintain nutrient intake even if animals eat slightly less during warm midday hours (11am – 3pm).
- Provide free-choice minerals: ruminants lose vital electrolytes like sodium and potassium through sweat and saliva as they adapt to summer. Provide weather-resistant mineral blocks or loose mineral mixers in grazing zones.
4. Prepare infrastructure ahead of the heat
Taking full advantage of summer includes strategies to avoiding heat stress. Early structural maintenance ensures a seamless transition. For those following more intensive farming models, this will include the following:
- Maximise airflow: clean out kraal, feedlot and barn ventilation fans, service automated curtain systems, and ensure ridge vents are clear to capture natural summer breezes.
- Secure water availability and delivery: ruminant water consumption can double in the summer. Inspect water lines, clean troughs, and ensure pressure pumps can handle high-volume demand across all watering points.
- Establish shade lines and zones: ensure rotational grazing camps have access to mature trees or portable shade structures to protect livestock during peak UV hours.
Contact PJ at 072 073 6805
Photo: ronyescobarhn on Pexels
