Feedstuffs PDF - Spring 2025

Feedstuffs Dr Munetsi Tagwireyi Assistant Professor, Large Animal Medicine Dr Dennis French, Large Animal Medicine Learning objectives Appreciate differences: - grasses & legumes - know grasses & legumes used in pastures & forage - forages: grazing, greench...

Feedstuffs Dr Munetsi Tagwireyi Assistant Professor, Large Animal Medicine Dr Dennis French, Large Animal Medicine Learning objectives Appreciate differences: - grasses & legumes - know grasses & legumes used in pastures & forage - forages: grazing, greenchop, hay & silage - major cereals: wheat, oats, barley, corn & sorghum - high-energy by-products - supplemental protein sources - distillery & brewery products Plant structure Young plants have single outer layer (primary cell wall) As it matures, second layer is formed inside of the cell Secondary cell wall gives plant structural strength - reduces palatability & digestibility - advancing maturity more lignin Monogastrics - limited ability to digest plant cell wall compounds Forage eaters depend on microbial populations in GI tract to ferment cell wall constituents into usable nutrients Grasses and Legumes Grasses & legumes are the most important types of plants used as animal feed. When used in combination they can provide animals with all the nutrients needed. Grasses are generally high in fiber & relatively low in protein Legumes are generally high in protein & relatively low in fiber. Alfalfa Grasses Pasture grasses are a type of grass that is commonly found in fields. Maintaining consistency of forage quality & quantity is a major problem with pasture grazing. These grasses are used for grazing & hay production. - hay must be preserved at DM above 85% Grasses Bermuda grass Brome grass Timothy Orchard Grass Native Grasses Legumes high nutritional value if processed at early bud stage main disadvantages : - lower persistence than grass under grazing - high risk of bloat - difficulty to conserve as silage or hay. Legumes Alfalfa Sweet Clover Red Clover Alsike clover White Clover Major Cereals Oats Sorghum Corn Barley Wheat Cost of hay feeding Doubles cost for the same amount of nutrients from pasture Large investment in equipment Labor to make & feed 50% wasted by either poor storage methods or improper feeding practices Green Chop Silage Corn usually cut into particles 1/2 - 3/4 inches in length This packs more firmly in the silo & is more palatable to cattle Finer cut silage increased amount of dry matter - less palatable & results in lower butterfat tests when fed as the primary source of roughage for dairy cattle Silage making Corn plant is cut & stored under anaerobic condition At temps between 80 -100° Bacteria use starches & sugars from plant Produce acetic & lactic acids which overwhelm bacteria pH of 4.2 is ideal & should occur in 3 weeks Too wet seepage &/mould Too dry poor packing Silage  Silage Quality Quality is determined by: - energy content - animal intake potential - content of protein & minerals No evidence that silage additives increase feeding value Lower NDF (neutral detergent fiber) & ADF (acid detergent fiber) are desirable NDF voluntary consumption of forages ADF energy concentration  High-Energy by-products Forages do not always have adequate energy content to meet the requirements of some cattle categories Lowers the cost of rations Allows farmers to maintain ration quality while reducing reliance on grain These include: - molasses - sugar beet - citrus pulps - fats & oils Molasses A viscous, dark & sugar-rich by-product of sugar extraction Impt role in livestock feed - good energy source - binding agent - anti-dust agent - palatability enhancer - silage additive - urea carrier Large amounts are toxic to livestock - has excessive potassium Sugar beet Have a nutrient profile similar to corn silage Good sugar content & digestible fibre Used in feeding ruminants, pigs & rabbits Recommended to cut them to eliminate the possibility of one lodging in the esophagus & causing bloat High moisture levels presents storage challenges Citrus pulps Solid residue that remains after fresh fruits are squeezed for their juice Can be fed dried or fresh Used in ruminant feeds - due to its high energy content & good digestibility Less valuable to pigs & poultry - due to fibre content & the presence of limonin in the seeds, which is toxic to monogastrics Unbalanced Ca:P ratio milk fever Susceptible to mould Fats & oils Fat is described by its origin, melting point, amount of free fatty acids, colour & impurities. Fats added to feeds with the following effects: - rich in energy & increases the energy value - often the cheapest available energy source - addition of fat permits the inclusion of other low-energy, low-cost materials - some of the fatty acids are essential to animals - increase palatability - eliminate dustiness in compounded feeds - possible to decrease the amount of excrement by 50% adding about 7% fat to feed of monogastric animals Antioxidants are added to prevent them from becoming rancid Supplemental protein sources Protein is one of the most expensive nutrients Availability of protein sources for diet formulation is a challenge Animals consuming low-quality forages require additional protein These include: - soybean meal - cotton seed meal - sunflower meal - peanut meal - linseed meal - canola meal Soybean meal SBM accounts for 84% of all the high-protein oilseed meal used in livestock rations. Provides a “total value package” that is composed of the most valuable nutrients needed in animal diets: - superior AA profile & AA digestibility - increased metabolizable energy - lower fiber content - higher total phosphorus - greater uniformity among batches Cotton seed meal CSM is commonly used as a protein supplement for beef cattle. It contains abt 1% gossypol which restricts its utilization in ruminant feed - toxic & hazardous more to non ruminants than ruminants. 40 – 45% protein Low in lysine & minerals Sunflower meal SFM in terms of production, it is the 4th most important oil meal after SBM, Rapeseed Meal & CSM. Primarily used in livestock & poultry nutrition High in fiber Peanut meal Peanut meal is considered as an excellent feed ingredient - high protein content (50 – 55 %) - low fibre - high oil - relative absence of antinutritional factors Aflatoxin contamination remains a serious issue  Linseed meal Linseed meal has attracted considerable attention due to the presence of polyunsaturated fatty acids: - alpha-linolenic acid & linoleic acid. - supplying these fatty acids to the diets of livestock is being used to alter the fatty acid profile of meat, milk & eggs - this provides health benefits to people. Contains 30-39% protein Unprocessed linseed meals processed under a low temperature can be toxic to animals (notably monogastrics) - in the presence of moisture, linase (enzyme) releases hydrogen cynanide (HCN)  Canola meal Excellent AA profile: - high levels of methionine, lysine & arginine Rich in vitamins & essential minerals. Low levels of glucosinolates (anti-nutritional factors) - nontoxic but adversely affect animal performance Increase milk production Corn gluten meal CGM is a by-product of the manufacture of maize starch Protein-rich feed, containing about 65% crude protein (DM), - used in livestock, fish & pet food Distillery & brewery products Solid residue left after the processing of cereal grains for the production of beer Barley is the main grain used for brewing but wheat, maize, rice, sorghum & millet Used to feed ruminant & monogastrics Rich in protein (27-33% DM) Relatively rich in fibre (ADF 17-26%) Susceptible to bacterial & fungal contamination