Unit 5 Part 1 Roughages Introduction l Roughages

Unit 5 Part 1 Roughages

Introduction l Roughages are bulky feeds l High in fiber l Low in energy l Mainly for herbivores ¡Ruminants and Non-ruminants l Nutrients made available by— ¡Microbial digestion ¡In Rumen or hindgut

Forages l Plants grown specifically for livestock l Cultivated or tame l Mainly grasses and legumes ¡Pasture, hay or silage l Approximately 100 billion tons of cellulose produced every year by plants. l Cellulose = Glucose

Chemical and Structure of Forage l Predominant characteristic is— ¡High content of cell wall material ¡This is cellulose, lignin, hemicellulose and silica l Cellulose and lignin— ¡Structural strength l Hemicellulose— ¡Complex carbs containing sugars.

Protein and Nitrogenous Compounds of Forages l Some protein and various NPN ¡Amino acids, amides, nitrates, ammonia l Major protein is chloroplast protein l Leaf proteins are the highest quality l Forages may contain tannins— ¡Legumes, these have high level of protected protein.

Carbohydrates in Forages l Nonstructural— ¡Starches, fructosans, simple sugars (g, s, f) l C 4 Plants have starch— ¡In stems and leaves l C 3 Plants have starch— ¡Only in the stems l Structural Carbs are in the cell wall. ¡Fiber.

Minerals in Forages l Dependant on plant species and soil type l Trace minerals = soil type l Legumes are higher in Ca ¡Also higher Mg. l Tropical legumes lower in P than temperate l Pastures often low in P for grazing animals

Vitamins in Forages l Ruminants get Vitamin B from rumen ¡Microbial activity l Vitamin K also synthesized in gut l Vitamin D from sun exposure l Vitamin A and E need to be provided ¡Green forages excellent source of A and ßcarotene. ¡No green pasture= supplementation

Deleterious Factors l Many forages contain— ¡Alkaloids, glycosides, toxic amino acids, mycotoxins

Factors Affecting Forage Quality

Plant Anatomy and Morphology l Leafiness associated with forage quality l Leaves are— ¡higher in protein and energy, lower in fiber and higher in digestibility than stems. l Quality decreases with maturity ¡Increasing stem proportion ¡Also increase in lignin content. (outer cell wall)

Environmental and Seasonal Factors l High temps promote lignification ¡And reduce forage digestibility ¡ 1 st cutting better than 2 nd, so on. l Increase in metabolic rate of tissue ¡Reduce size of metabolites in cell ¡Decreasing protein and soluble carbs ¡Increasing structural carbs and cell wall.

Genetic Factors and Forage Quality l Between species and cultivars l Vary in decline of quality with maturity. l Selection is of importance in the variety and cultivars of these grasses and legumes

Assessment of Forage Quality

Digestibility and Forage Quality l Important for 2 reasons— l 1. Higher the digestibility, more nutrients liberated for the animal l 2. Digestibility increases, feed intake can increase due to turnover rate in the rumen increases.

Digestibility and Forage Quality l Can be done in vivo (living animal) Ch 1 l Forage digestibility can be done in vitro ¡In glass or in a test tube l Put buffer solution, test forage, rumen microbes, and incubate at body temperature l Buffer solution acts as saliva ¡Buffers the acid produced during fermentation

Digestibility and Forage Quality l Rumen microbes from fistulated animal l Test forages added and gassed with CO 2 to create anaerobic conditions l Placed in bath water to 37 C, 24 -48 h. l Tubes filtered and non-digested material remains.

Factors Affecting Digestibility of Roughages l Population of rumen microbes. l If have roughage, need microbial flora— ¡Cellulolytic and saccharolytic ¡Sugar-digesting bacteria ¡Produce acetate as main end product l High starch diets— ¡Amylolytic bacteria l. Ferment starch, sugars and hemicellulose

Factors Affecting Digestibility of Roughages l p. H of rumen is lower when on concentrate diets than high roughage diets. ¡Decreased rumination ¡Reduced salivation l When feed is consumed, particles are buoyant and float to top (called RAFT). l As degraded, sink and exit rumen.

Rumination l A major animal factor influencing the efficiency of roughage utilization is the rumination rate l Rumination helps to degrade fibrous material into smaller particle sizes, aiding in their digestion by microbes l The maximum time spent in rumination is 8 to 9 hours a day ¡ So the more roughage that can be ruminated during that time, the greater the efficiency of digestion, roughage intake, and productivity

Rumination l Cattle are more efficient in rumination than sheep, where goats are in between ¡ Cattle ¡ Goats ¡ Sheep l Calve ruminate less efficiently than mature bovines – ¡ Younger cattle should be fed better-quality hay than cows l Cattle can utilize low quality roughage better than sheep

Feed Consumption l Forages don’t supply sufficient energy for maximum growth for animals. l Higher the consumption, close to satisfying l Intake of forage by ruminants— ¡Closely related to digestibility l Voluntary intake also depends on— ¡palatabilty

Forages for Pasture, Silage and Hay

General Nutritional and Toxic Properties of Grasses lower in CP, DE, Ca and Mg than legumes l Value decrease markedly with maturity l Palatability follows similar trend l 2 Problems— ¡ 1. Nitrate poisoning ¡ 2. Grass tetany

Nitrate Poisoning l Grasses heavy fertilized by N l Excess is accumulated l Nitrite is the actual toxic entity l Nitrite absorbed and reacts with hemoglobin forming methemoglobin. ¡Can’t carry oxygen, poisoning death due to oxygen starvation

Grass Tetany l Metabolic disorder l Caused by very low blood levels of Mg. l Signs are incoordination and convulsions l High mortality l Spring grasses are low in Mg.

Small Grains as Forages l Hay, silage or pasture of small grains l Stockers on winter wheat pasture. l Grazing wheat increases grain yield by reducing lodging. ¡Falling over by wind l Wheat pasture poisoning— ¡Usually beef cows grazing winter wheat.

Legumes as a Forage l Have symbiotic relationship-¡Bacteria in root nodules; utilize atmospheric N ¡Fix their own N l Nutritionally superior to grasses ¡Protein, energy, Ca, Mg

Legumes as a Forage l Bloat hazard with legumes ¡Gases produced in rumen fermentation become trapped in the rumen in the form of a stable foam ¡At the base of the esophagus, enabling to regurgitate. l Give anti-bloating agents— ¡Poloxalene “Bloat Guard”

Legumes as a Forage l Alfalfa important to dairy industry l Protein and fiber source. l High Ca content make excellent source for — ¡Rapidly growing or lactating animals.