Applied Animal Nutrition-I

Feeds, forages, feedstuffs, nutrients

FEEDS, FORAGES, FEEDSTUFFS AND NUTRIENTS

Nutrient

• It is defined as any food constituent or group of food constituents of the same general composition that aids in the support of animal life.
• There are six classes of nutrients that are essential to every living animal for survival:
  • Water
  • Protein 
  • Carbohydrates 
  • Fats/Lipids 
  • Vitamins 
  • Minerals

Functions of Nutrients

• Basic functions
  • Maintenance and building of body structures : Water, protein, fat, minerals, vitamins.
  • Serve as source of energy for heat production, work and fat deposition: Carbohydrates, fats and proteins. 
  • Regulate body processes or they are required for formation of body produced regulators. Vitamins, minerals, certain amino acids and fatty acids.
• Accesory functions:
• Production of milk, egg, meat, wool etc. 

Feedstuffs used in ruminant nutrition

• Balanced rations for ruminants are made up of five basic types of feed. When combined in the right amounts, these feeds can supply all the nutrients needed to keep cattle healthy and productive. The five types of feed are:

Bulk forages for energy

• These are mostly grass-like plants that have long stems, long narrow leaves and flower spikes and contain a lot of fibre in their structure. They include fresh materials, such as green grass, as well as dry materials, such as hay. They provide most of the energy a cow needs and some minerals and will make up most of the ration – they are what fills the animal and stops it feeling hungry. Most bulk forages contain only low levels of protein. They often grow naturally, such as grass and other plants on roadside reserves or natural pastures, or are the part of the plant left over when crops grown for people are harvested, such as stovers or straws of maize, sorghum wheat or rice. Napier grass is often grown on the farm as bulk forage.

Supplementary forages for energy and protein

• Supplementary forages provide both energy and protein and some minerals. These are fibrous plants, similar to bulk forages, but they are usually especially grown on the farm as feed for cattle and contain higher protein and/or energy levels than bulk forages. Most are legumes and include herbaceous plants, shrubs and trees. They are fed in addition to the bulk forages, usually in smaller amounts. They can be used either to
  compensate for poor quality bulk forages or they can be used as substitutes for concentrates. The feeding value of different supplementary forages varies; for calliandra, three kilograms of fresh forage is equivalent to one kilogram of a good quality commercial dairy meal.

Concentrates for energy and protein

• These are feeds that supply more highly concentrated nutrients than forages. They contain high levels of protein or energy or both, and also some minerals. They are also low in fibre and easy to digest. They include specially made feeds, such as commercial dairy meals, as well as cereal by-products (wheat germ, maize germ) and other high energy and/or high protein feedstuffs (molasses, fish meal and brewers’ dried grains). Cereal grains such as maize, wheat and barley, if available and economical to feed.
  Concentrates are expensive and are therefore fed in small amounts in addition to forages; the amounts fed should depend on the milk produced by a cow.

Mineral supplements

• Although some minerals are naturally present in bulk and supplementary forages and concentrates, dairy cows also need to be regularly fed additional minerals. This is most easily done by regularly offering access to a commercially manufactured mineral supplement.

Vitamins supplements

• Not a problem with practical dairy cow rations: some vitamins are made by the micro-organisms in the rumen and others are naturally present in feeds, such as leafy green forages.

Water, essential for life

• Ideally, dairy cows should have access to clean drinking water at all times. In addition to the amount required for normal bodily functioning, a milking cow requires about five litres of water to produce one litre of milk. A cow will also drink more water in hot weather.

Forages or fodders 

• Bulk forages
• Supplementary forages

Bulk forages

• The cheapest ingredients and the ones that form the largest part of the dairy ruminant rations, are the bulk forages. These are plant feeds with high fibre contents such as fresh grass, , weeds, hay, straw and stovers. 
• Forages that are specially grown for feeding to livestock, such as Napier grass or fodder legumes, are usually referred to as fodders.
• Forages can be fed to animals either fresh (grazed directly or cut-and-carried), dried (as hay) or preserved as silage. 
• Some forages, such as Napier grass, which have long stems, should be chopped into approximately 3 cm lengths before feeding to cattle. This makes it easier to mix with other feeds, such as concentrates, and also prevents wastage by making it more difficult for cattle to select only their favourite parts of the plant.
• To remain healthy, stimulate rumination and produce good quality milk with a high fat content, the dairy cow’s ration has to contain enough forage; at least 70  per cent of the dry matter content of the ration should come from forage. 
• Dry cows can survive  on forage alone and, provided they are given enough good quality forage, milking cows can produce 5 to 10 litres of milk per day from forage alone. 
• But if the forage is of poor quality (Rice straw or dry maize stover)  then production levels from forage will be much lower. 
• Higher milk producing cows cannot eat enough bulk forage to obtain all the nutrients they need – their gut fill  before they are able to absorb sufficient nutrients - and they have to be given other, more nutrient-rich feeds which are called supplements. 
• Supplements can be 
  • better quality forages, or
  • concentrates.

Quality of bulk forages

Good

• Young grasses like Napier , Rhodes, sorghum, fodder maize etc cut and fed to animals when they are at prefloweing stage or the hay or silage.

Medium

• Napier grass (1 to 2 metres tall),
• Rhodes/Setaria grass (yellowing leaves and stems; seed set)
• Fodder sorghum (yellowing leaves and stems; seeds set and dropped)
• Mature pasture/grass (yellowing leaves and stems; seed set)
• Green maize stover (fresh, green leaves and stalks with cobs removed;
• Hay (made after seed set)
• Mature roadside grass (seed set, leaves and stems drying and turning yellow)
• Sugarcane tops 

Poor 

• Overgrown Napier grass ((more than 2 metres tall)
• Dry maize or sorghum (stover after harvesting of the cob)
• Straws (Rice, Wheat and Barley )
• Dry pasture/grass (dry leaves and dry, hard stems;seed dropped)

Supplementary forages

• Fibrous plants similar to bulk forages but they have higher level of protein and energy than ordinary bulk forages. Most supplementary forages are legumes crops, especially grown on the farm to feed dairy cattle. They include herbaceous legumes, such as lucerne and desmodium, and legume shrubs and trees grown for their leaves such as calliandra. They are classified as medium to high quality feeds in terms of their protein and energy content.
• Can be used in two ways: to compensate for poor quality bulk forages or to substitute for concentrates.
• Can be fed fresh, dried as hay, leaves of shrub and tree legumes as dry leaf meal, or preserved as silage. But they should be fed with caution as feeding large amounts of some supplementary forages can cause bloat and other problems.
• Should not make up more than 25 to 30 per cent of the ration on an as-fed basis.

Examples

• All legume forages such as cowpea, berseem, pillipesara, Hedge Lucerne, Stylo etc
• Tree leaves such as subabul, sesbania, gliricidia, mulberry leaves .