Climate change and productivity

Climate change is a long-term change in climatic/weather patterns of the earth or region. Such change is observed in temperature and rainfall patterns, amongst others. It has consistently been reported that the earth's temperature is on an increase and that rainfall activities have become unpredictable in many parts of the world, and Namibia is evidently also experiencing the adverse effects of climate change. Agricultural output is primarily driven by climatic events, and these have adverse effects on both food and water availability in agro-ecosystems, hampering sustainable crop and livestock productivity, as well as farmers' livelihoods.Climate change effects can be direct or indirect. Livestock productivity is directly reliant on rangeland productivity, which in turn is determined by soil moisture availability and environmental temperature. The management aspects, as secondary determinants of agricultural output, should therefore aim at mitigating or enhancing farmers' adaptation to climate change events. Climate change has been characterised by increases in environmental temperature, hence the extreme heat wave being experienced in all parts of Namibia currently, and figures of more than 40 degrees Celsius were recorded, especially in the southern regions. The direct impact of this on livestock is heat stress, which negatively affects their wellbeing and performance. Heat stress and feed intakeWhen an animal is eating, the digestive processes generate heat and increase the body temperature. For example, the normal body temperatures of cattle, sheep and goats are 38.5, 39 and 39.5 degrees Celsius respectively. When the body temperature increases beyond normal, then an animal's physiological functioning is affected and could be detrimental or life-threatening in extreme cases. These ruminant animals (cattle, goats and sheep) under normal circumstances will prefer to graze/forage during cooler hours of the day (early morning, late afternoon or night) to avoid heat stress. They would only rest during the hot hours of the day to ruminate or re-chew the food they have eaten, breaking it into smaller pieces to enhance digestion further.Grazing during hot hours will mean too much heat on the animal, from sunlight and the internal digestive processes, causing heat stress. This means the animal's physical activities such as walking and feed intake will have to be reduced in order to maintain normal or optimal body temperature, and this in turn compromises the animal's nutrition and health status, and the overall performance. This will be experienced as nutrient deficiencies, poor growth rates and body condition, reduced milk yield and poor reproduction, amongst others. Heat stress and reproductionHigh temperature also affects livestock reproduction. The heat stress forces animals to reduce their exhaustive physical activities, which also includes mating. The female animal's reproductive system as well as the sperm production process in male animals can be adversely affected by high temperature. Heat stress is said to depress the release of reproductive hormones such as the oestrogen and progesterone, compromising the consequent processes of oocyte (female egg cell) growth, oestrus (heat) cycle, conception, embryo development and foetus growth, amongst others. In male animals, high temperature negatively affects the process of sperm production, leading to temporal infertility. Preventing heat stress in livestockAlthough animals have the ability to adapt to environmental conditions and management regimes, hot environments will compromise their potential physiological functioning and overall performance to some degree. It is therefore advisable to minimise the exposure of your animals to extremely high temperatures.The most available mechanism is when the animals themselves laze in the shade under the tress when they are out in the veld. It is critical to provide shade in kraals by having trees or by using shade nets or other appropriate shading structures. This is very important especially for the calves, kids and lambs that spend a lot of time, or in some cases, a whole day in the kraal without any shelter.In hot environments or when animals forage during the hot hours of the day, the water demand or intake increases. Thus, animals should have daily access to clean, cool and sufficient water. Water has the direct role of quenching thirst and in digestion, and is importantly used as a coolant by animals through sweating.During the current drought, farmers will be relocating their animals to “greener pastures”. It is important that the animals be transported during the cooler hours of the day, and to have stopovers along the way for them to rest or even drink water, especially when trekking. The transport vehicle should also be well-covered to provide sufficient shade and ventilation at the same time. It is also advisable to execute routine husbandry practices, such as vaccination or branding during the cooler hours or early morning.Lastly, if animals have to adapt to new environments, they will have a lot to change, including food preference, foraging times, respiration rates and water intake, amongst others. Farmers should also adjust their management regimes to respond to the animals' demand or requirements.*Erastus Ngaruka is the technical officer: livestock within Agribank's agri advisory services division.Erastus Ngaruka

Climate change and productivity

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Namibian Sun 2025-05-20

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Climate change and productivity

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Namibian Sun 2025-05-20

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