Heat stress affects pigs, cattle and poultry
In Germany, too, climate change is leading to ever longer and hotter periods of heat. The summers of 2018, 2019 and 2020 have practically "burned" into the national memory. Extreme temperatures not only put a strain on people, but also on farm animals. Pet owners have to respond to this. By 2030, the European Union wants to reduce greenhouse gas emissions to 55 percent below the 1990 level. Reducing CO2 emissions is a key element in the fight against climate change. The decision is ambitious, but leaves questions unanswered as to how the goal can be achieved. The consequences of climate change can be seen in rising temperatures and, at the same time, more frequent extreme weather conditions.
Forecasts predict that mean annual precipitation will remain unchanged, but its distribution will change. Higher winter and lower summer precipitation is expected. In addition, the soils dry out faster at high temperatures in summer. This has direct consequences for agriculture. The question of the weather is as old as agriculture. However, farmers have to react to the increasingly extreme conditions caused by climate change and global warming with new concepts. This also applies to farms that keep animals.
Heat spoils appetite
In extreme weather situations it becomes difficult to bring the necessary amounts of feed into the barn. This has a direct impact on the cattle's forage supply. There have already been bottlenecks here in the past due to a lack of growth. The forage quality also suffers when harvesting conditions are unfavorable. Cattle, and above all dairy cows, react to heat stress with lower feed consumption and lower performance up to and including health problems such as uterine and udder infections. Studies have shown that heat stress has significant effects, especially in the preparatory and transit phases.
Stable management is of particular importance in periods of extreme heat. Cattle showers are therefore increasingly finding their way into the cow stalls. Adjustments in the stable construction, for example in the shade and air flow, improve the stable climate. Since the water requirement for regulating the body's own heat balance increases significantly when it is hot, sufficient watering devices with a corresponding flow rate must be kept available. To meet their water needs, cows drink an average of nine times a day and drink 18 to 25 liters of water per minute. Cows need around 120 liters of water every day, and significantly more in summer. Cattle breeding goes its own way. Certain breeding programs aim to compensate for the reduced performance due to heat stress through increased protein efficiency or to improve the heat output through a shorter and smoother coat.
Even the offspring of heat-stressed cows are often already damaged and there are rearing losses. In principle, however, calves can cope with heat of up to 26 degrees as long as they are not exposed to direct sunlight. Heat stress in calves manifests itself, for example, in that they stand more than they lie or breathe heavily. Regulating body temperature costs energy, which has a negative effect on daily weight gain and the immune system. In hot phases, special attention must therefore be paid to stable hygiene. Shading and free access to fresh water are essential. Additional stresses such as moving to shelters should be avoided or moved to cooler times of day.
Pigs need cool corners
In pig farming, critical temperatures are reached at outside temperatures of 25 degrees Celsius. Lighter animals are less susceptible than heavier ones. Only a few functional sweat glands are available to the pigs, so they are dependent on cool areas to lie on. In addition, pigs cool down through increased breathing, which leads to water loss and reduced feed consumption. Blood is required for further cooling in the extremities and a cycle is set in motion, which ultimately leads to an undersupply of the intestinal cells and an increased permeability of the intestine. In this phase, it is important to feed as unpolluted feed (mycotoxins) as possible. It has also proven useful to reduce the crude protein content, to replace the starch content in the feed with fat as an energy source and to lower the crude fiber content. The stable climate and its control, cooling and an adequate supply of clean water are of particular importance.
During periods of heat, the boars' fertility performance and the farrowing rate of the sows decrease, and the litter sizes decrease. The sows react to high temperatures with lower milk yield and become more susceptible to disease. These and other parameters have a direct effect on profitability. Investments in, for example, micro-chairs, showers, cool lounging areas or improvements to the stable climate have a direct positive impact.
Barn control is essential
Poultry can handle heat best, even if chickens cannot sweat. In young poultry, for example, the heat stress begins at around 30 degrees. Laying hens tend to prefer 18 to 24 degrees. When chickens get too hot, they spread their wings sideways from their bodies. This allows cooler air to get under the feathers to the skin and warm air to escape. In addition, chickens give off their heat through their tongues and mucous membranes. When breathing with an open beak, moisture is released and the evaporation cold is used for cooling. Hens react to the onset of overheating by decreasing egg production.
A balance or a stress compensation is quite easily possible with poultry through feed. For example, reduced crude protein levels reduce metabolic heat production. Feed additives and complementary feed can support the metabolism in the hot season. A key figure for the heat load in poultry is the enthalpy. It indicates the total heat content of the air and is calculated from the combination of temperature and humidity. A critical range is already reached at a temperature of 25 degrees with a humidity of 80 percent, for example. This corresponds to an enthalpy value of 67 kJ / kg air. Heat death can occur at values of 72 kJ / kg air.
Daily barn control is also vital in poultry farming, on the one hand to check the condition of the animals, but also to check whether the barn technology is working properly.
