Dear Daktari, I am a regular reader of your informative articles on livestock health and production. I keep a few diary animals and wanted to know how much feed I should give my cows and what factors determine the amount of feed intake. [Benjamin Mwadime, Taita Taveta County]
Thank you Mr Mwadime for reaching out. This question boils down to dry matter (DM). DM refers to material remaining after removal of water from feeds. Moisture content reflects the amount of water present in the feed ingredient. The nutrients in feeds, required by the animal for maintenance, growth, pregnancy, and lactation, are contained in the dry matter. Depending on the quality of the feed, a mature cow will consume one to three per cent of her total body weight. Please note that when fed on a low-quality feed this will go down to one to two per cent of the body weight. If you understand this statement, you will be a better farmer when it comes to feeding your cows and you will certainly get more milk or meat from them. It is pointless to feed your cow on low quality feeds because apart from it consuming little it will also lead in low milk production.
The speed of passage through the gut
How fast the feeds pass through digestive system of an animal has an incremental effect on intake. Higher passage happens with feeds that are easily digestible. This includes high quality feeds like lucerne. Poor quality feeds like straw on the other hand will take long to be digested and subsequently lower the intake. This can be explained by the fact that ruminants require proteins for the rapid multiplication of the gut microbes which later increase the digestion of fibres. More proteins mean more gut microbes faster digestion or passage of feeds hence an increase in intake. The effects will be poor production and slow growth rate.
Body size is another factor that determines feed intake. The bigger the animal the more the feed intake. Stage of growth is another factor – young animals will not only require feeds rich in protein but also other nutrients to build their body. Level of production is another factor: Animals that are lactating and gestating animals will consume more feeds to cater for the production of milk and the growing foetus. Availability of feeds is an environmental factor that also affects how much an animal will eat. In times of abundance, great amounts of feeds may be consumed and this can at times be detrimental to the health of an animal. A good example is the grain overload for animals exposed to lots of maize seeds or lush pastures that cause diarrhoea.
Palatability is the ease with which feeds are eaten by the animal. Palatable feeds are likely to be eaten in large quantities compared to unpalatable feeds. Addition of feed additives like molasses sweeten feeds and significantly increases their intake. Bitter tasting feeds will be consumed in less amounts.
[Dr Othieno Joseph is a veterinary surgeon and head of communications at the Food and Agriculture Organisation of the United Nations (FAO) Kenya. The views expressed here are not necessarily those of FAO]