Livestock feeds are broadly classified into two groups. These are roughages and concentrates. Besides, there are feed supplements (vitamins and minerals) and feed additives.
The feedstuffs that contain more than 18% crude fiber (CF) and less than 60% total digestible nutrients (TDN) are called roughages. Roughages are bulky in nature and a poor source of readily available carbohydrates. It may be of two types based on moisture content, viz., dry roughages and succulent roughages.
1. Dry roughages: They contain about 10%-15% moisture, e.g. straw, hay, etc. Straw may be of paddy, wheat, maize, Jowar, Bajra, etc., out of which paddy straw is popular as livestock feed. However, the nutritive value of paddy straw is poor. It contains about 45% TDN and only 3% protein. It also contains a high quantity of lignin (mostly indigestible) and oxalic acid (1.6%). Oxalic acid combines with calcium to form calcium oxalate and excreted through feces and makes the calcium unavailable for the animals. Hay is sun-dried green grasses preserved for future use and contains more than 75% dry matter.
2. Succulent roughages: It contains about 60%-90% moisture, e.g. pasture grass (range plants), fodder (cultivated fodder crops), tree leaves, silage, root crops, brewery by-products, and food processing plant wastes, etc. Pasture grasses are Doob, Anjan, Chengali, etc. Fodders may be leguminous type having more protein content (Berseem, Lucerne, Cowpea, Rice bean, etc.) and nonleguminous type having less protein but more energy content (maize, Jowar/sorghum, Bajra/pearl millet, oats, barley, para grass, hybrid Napier, guinea grass, etc.). Common tree leaves used as livestock feed are sSubabul, babul, bamboo, mulberry, etc. Roo is beet, turnips, carrot, etc. Silage is preserved fodder crops under anaerobic conditions, having about 70% moisture.
- Berseem and Lucerne (Alfalfa) are winter legumes (rabi fodder). Berseem is known as ‘king of fodder, and Lucerne is known as ‘queen of fodder’.
- Cow pea, rice bean, and guar are summer legumes (Kharif fodder).
- Maize and Jowar is a major Kharif non-leguminous fodder crop.
- Oats and barley is important rabi non-leguminous fodder crops.
- Guar (cluster bean) is a drought-resistant legume.
- Silage is anaerobically fermented products of green forages, also known as pickle green fodder’. The optimum pH of very good silage is 3.7-4.2. Less amount of Vitamin D is available in silage than hay.
- Thick-stemmed crops are suitable for silage making. Maize is an ideal crop for silage making. Jowar is also a good crop for silage.
- Thin-stemmed crops like Lucerne, oats, and grasses are suitable for haymaking.
The feedstuffs that contain less than 18% crude fiber (CF) and more than 60% total digestible nutrients (TDN) are called concentrates. Concentrates are rich in nutrients. They have less moisture, and these are usually more digestible than roughages. Based on nutrient contents, especially crude protein (CP) content, concentrates are divided into two groups. These are energy-rich concentrates and protein-rich concentrates.
1. Energy-rich concentrates: They have less than 18% CP, e-g. cereal grains (maize, sorghum, barley, oats, wheat, broken rice, etc.), mill by-products (tour, rice bran, wheat bran, rice polish, etc.), molasses (obtained from sugar industry).
2. Protein-rich concentrates: They have more than 18% CP. It may be of two types, viz., plant origin and animal origin.
Protein-rich concentrates of plant origin are different types of oil cakes like groundnut cake (GNC), soybean cake, mustard cake, sesame (Till) cake, linseed (Tisi) cake, sunflower cake. etc. Protein-rich concentrates of animal origin are fish meal, meat meal. etc.
The difference between concentrates and roughages are:
(3) Feed Supplements
Feed supplements are categorized into two groups-mineral supplements and vitamin supplements. Animals usually get these vitamins and minerals from various feed sources.
However, in most cases, livestock feeds based on concentrate and roughage are generally deficient in minerals, especially calcium, phosphorus, sodium, zinc, iron, copper, manganese, and iodine, etc. Therefore, these mineral supplements are to be provided to the animals from outside sources.
Ruminant animals (cattle, buffalo, sheep, goat), having functional rumen, do not require dietary supplementation of vitamins (water-soluble vitamins and fat-soluble Vitamin K). Animals exposed to sunlight can synthesize Vitamin D. Similarly, animals receiving sufficient green forages need no supplementation of Vitamins A and E.
Vitamin and mineral supplements are available in the markets in various trade names. These feed supplements may be fed to animals as such through drinking water or as electuary, or mixed with feed, as and when needed. When it is used, it should be fed continuously at least for 10 days. Feed supplements are used to prevent deficiency diseases, and to promote growth and production.
(4) Feed Additives
These are not essential nutrients, but their presence in feed-in minute quantity promotes intake, digestion, and utilization of feed. Finally, they increase the nutritive value of feed leading to increased feed efficiency, growth, and production of animals. An additive is an ingredient or combination of ingredients added to the basic feed mixture, which is to be handled and mixed carefully. The most common feed additives are antibiotic growth promoters, probiotics, antioxidants, enzymes, anticoccidials, antifungals and toxin binders, antistress medicines, anthelmintics, immuno-stimulants, electrolytes, etc.
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