Some farming areas in Namibia are faced with severe forage scarcity, especially grazing materials due to overgrazing and drought conditions.
Moreover, the situation may further deteriorate if the anticipated rainfall activities are not favourable. Existing conditions and scarce options for alternative grazing have prompted many farmers to adopt the most obvious drought management strategy which is to feed their animals.
Farmers are now battling to source a myriad of feed stuffs for their livestock to survive until grazing conditions become favourable. To this end, there are various feed resources in the form of crops and their residues, commercially formulated feeds, and processed forage feeds which include bush, pods and pasture amongst others that farmers can use.
However, the feed stuffs or ingredients that farmers use may have detrimental effects if processed, stored, or used inappropriately. For instance, there have been several cases of livestock showing symptoms or dying because of improper feeding practices.
Some of the suspected or observed health conditions include acidosis, pulpy kidney, listeriosis, and urea poisoning amongst others. These can result mainly from overfeeding, improper processing and mixing, and feed spoilage.
Overfeeding is when an animal excessively eats a particular feed at an instant.
Amongst others, the main predisposing factors leading to overfeeding include, hunger,free access and oversupply of feed. Given the drought conditions, and insufficient forage materials, animals will have higher feed intake than normal when introduced to supplementary feeds.The most common disease affecting goats and sheep resulting from overfeeding or a sudden change in their diet is Enterotoxaemia (pulpy kidney). The disease is caused by bacteria (Clostridium perfrigins type D) that live in the animal’s digestive tract. When digestive disturbance or sudden change in the digestive environment occurs, the bacteria proliferate and produce toxins that poison the animal.
This disturbance or change can come from changing diets and deworming animals. This means animals need to be first vaccinated against pulpy kidney before these changes. The symptoms include depression, abdominal pain, convulsions, and lying on the side amongst others.
Treatment with antitoxin may not be successful, but an annual vaccination is necessary for prevention. The other health conditions resulting from overfeeding include bloat and acidosis.
Bloat occurs when the ruminal gas accumulates at a higher rate than can be released causing the stomach to distend or swell. Bloat can result from overeating lush feeds or fresh legumes (e.g. lucerne), wet grass pastures, or finely ground grains (e.g. maize). This is a painful condition and the symptoms include; restlessness, abdominaldiscomfort, excess salivation, respiratory distress, and belly kicking amongst others.
On the other hand, the causes of bloat are also associated with acidosis. Acidosis (acidic stomach, grain overload, Suurpens) is a metabolic disorder resulting from overeating of grain feeds or easily digestible feeds which in turn increases the acidity of the stomach (lower pH). The normal range of stomach acid (pH) level is 6.5 – 7.0; acidosis is when this pH level drops below 5.5. This causes abdominal pain, loss of appetite, and dehydration. In acute stages, both bloat and acidosis can be deadly.
Improper mixing of feeds poses danger to animals especially when certain ingredients in the rations contain potent substances. The most common feed ingredient during the dry season is urea used as a protein source for the rumen microbes so that they efficiently digest the feed. Urea can poison the animal if ingested in large amounts. This can happen when an animal picks up pieces of urea that are concentrated at one spot in the feed. On the other hand urea dissolves easily in water,thus, when a urea lick gets wet (e.g. from rain), an animal can be poisoned when it drinks the standing water in the lick trough. Urea containing feeds should be properly mixed and should contain sufficient energy components (e. g. maize) for effective utilization or fermentation of urea by the rumen microbes.
Spoiled or contaminated feeds are also a health hazard which can be attributed to improper storage of feeds. Feed storage is a drought preparedness practice as farmers are acquiring feeds in bulk in order to build up their fodder banks (feed reserves). Amongst others, feed spoilage can be attributed to inappropriate storage facilities (e.g., due to poor ventilation), storing wet feeds which could become mouldy and toxic (e.g., causing Listeriosis), dusty feeds which can cause respiratory problems (e.g., pasteurellosis), and storing feeds with other potentially harmful substances (e.g., herbicides).The risks associated with livestock feeding can be avoided. During a period of feed scarcity, animals will always have an increase in feed intake and a craving to meet their daily nutritional demands.
To this end, livestock will attempt to utilize any available feed resources at their disposal. It is very important that the animals are allowed to adapt to any new feed before they have full access (ad libitum). Urea containing feeds should not mix with water and should be properly mixed according to the manufacturers’ instructions. Lastly, always seek advice before purchasing and mixing feeds, thus, consulting with animal nutritionists, veterinarians and otheragricultural experts is vital.
* Erastus Ngaruka, Technical Advisor – Livestock & Rangeland
