• June 2nd, 2020

The Risk: Drought feeding strategy to drought feeding tragedy

Erastus Ngaruka

WINDHOEK - Most farming areas in Namibia are faced with severe forage scarcity, especially grazing materials due to overgrazing and drought, and the situation is getting worse as the normal dry season has set in, and with still several months of uncertainty ahead. 

Since there is very little or no options of alternative grazing areas for many farmers, the most obvious option is to feed the animals. Farmers are now battling to source all kinds of feedstuffs for their livestock to survive until the grazing conditions are favourable. 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, among others.  

The feed resources that are being used now may have detrimental effects if processed, stored or used inappropriately. Many farmers are already reporting abnormal animal behaviours or symptoms that are suspected to result from feeding. Some of the observed symptoms can be suspected on health conditions such as: bloat acidosis, pulpy kidney, listeriosis, and urea poisoning, among 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. Among 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 because of overfeeding or a sudden change in their diet is Enterotoxaemia (pulpy kidney, bloednier, Okatikitira). The diseases are caused by a bacteria (Clostridium perfrigins type D) living in the animal’s digestive tract already. The bacteria proliferate and produce toxins poisoning the animal. The symptoms include; depression, abdominal pain, convulsions, and lying on the side, among 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 faster rate than it 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, the symptoms include; restlessness, abdominal discomfort, excessing salivation, respiratory distress, and belly kicking, among others. On the other hand, the causes of bloat are also associated with acidosis. Acidosis (acid 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 component (e.g. maize) for effective utilisation or fermentation of urea by the rumen microbes. 

Spoiled feeds are also a health hazard, which can be attributed to improper storage of feeds. Feed storage is drought preparedness practice as farmers are acquiring feeds in bulk to build up their fodder banks (feed reserves). Amongst others, feeds spoilage can be attributed to inappropriate storage facilities (e.g. poor ventilation), storing wet feeds which could become mouldy and toxic (e.g. Listeriosis), dusty feeds which can cause respiratory problems, 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 demand. On that, they will try to utilise any available feed resources at their disposal. The animals must be 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 instructions from the feed manufacturers. Always seek advice before purchasing and mixing the feeds, thus, consulting with animal nutritionists, veterinarians and other agricultural experts is vital. 

Staff Reporter
2019-08-13 07:28:09 | 9 months ago

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