Livestock Nutrition

Livestock Nutrition Chapter 8 Feed Quality and Feed Analysis

Objectives • Describe quality Characteristics of grains and other feeds. • Describe methods of harvesting quality hay and silage. • Describe the analysis of feedstuffs. • Describe methods of measuring the value of feeds. • Describe regulations relating to the manufacture and sale of feed stuffs.

Feed Quality • Quality of feed affects its value for animal nutrition. • Quality factors include palatability and nutrient content. • Improper harvesting or handling will reduce quality. • Palatability refers to how well the animal will accept feed.

Feed Quality • If an animal does not find a feed palatable it will not eat enough, make good gains, grow properly or produce meat, milk or eggs. • Feeds on produced on well fertilized soils will produce feed, especially roughages, that is of a higher quality. • Vitamins, amino acid content and minerals will also be affected by soil type.

Harvesting Hay for Quality • Quality of hay is affected by harvesting and handling methods. • Stemmy hay with fewer leaves is of lower quality, because the leaves contain the most nutrients and are the easiest digest. • Shattering is the loss of leaves due to harvesting and handling.

Harvesting Hay for Quality • Legume hays will shatter easier than grass hays. • Moisture content of hay must be reduced so it can be stored without spoiling or serious loss of nutrients. • Field forages must not contain more than 18-22% moisture for baling. • Factors affecting moisture content include, humidity and movement of air, fineness of forage and how compact the bale is.

Harvesting Quality Hay • Shattering, leaching and bleaching are 3 things that cause loss of quality during harvesting. • When forages get too dry, leaves tend to shatter. • Forage that is rained on while curing will suffer loss of quality by leaching, (loss of water soluble nutrients. • Bleaching occurs when the forage has cured to long in extremely hot temperatures.

Harvesting Quality Hay • Forages should be cut as soon as possible after reaching the early bloom stage of maturity. • If hay is not conditioned it will require two days of drying before it is ready to bale. • Conditioning breaks the stems, reducing the amount of time that it takes dry the hay.

Harvesting Quality Hay • Hay should be baled as soon as possible after it reaches a safe moisture level for storage. • Delays in baling at this point will increase the chances of losing nutrients to bleaching and leaching. • If small square bales are not stored under cover they will lose quality due to moisture, causing musty and moldy bales. • Rain and snow can easily soak a small bale stack through and through

Producing Quality Silage • When high moisture crops are stored under anaerobic, without air, conditions, a fermentation process occurs that produces silage. • Crops may be stored is vertical or horizontal silos. • Vertical silos require less land, less spoilage and require less labor for unloading.

Vertical Silos • Can be either conventional or gas tight. • Conventional are constructed of concrete staves, metal, or cast in place concrete. • At time of ensiling crop should contain 25-35% moisture. • If crop is to high or low in moisture, spoilage will be high. • Gas tight silos are constructed to eliminate air, ensure preservation and storage of forages with a range of approximately 25-75% moisture.

Horizontal Silos • Trench, bunker and stack are the three types of horizontal silos. • A trench silo is usually dug into the side of a hill, a concrete bottom is recommended due to mud and water. • Filling is accomplished with dump trucks or wagons. • After filling the pit is covered with a polyethylene sheet and weighted with dirt, concrete blocks or boards.

Horizontal Silos • Bunker silos are posts and boards with a side lining of building paper or plastic. • Bunker silos are above ground, while pit or trench silos are below ground. • Bunkers silos are usually made with a concrete floor as well.

Horizontal Silos • Stack silos require a small investment and may be used for emergency storage of surplus silage. • Silage is spread in shallow layers using tractors, the sides should slope 60 degrees. • During filling the silage is packed with a tractor. • When filling is completed, the top of the stack is rounded off, black plastic 4-6 mil thick, is used to cover the stack. • The slack should be always taken out of the plastic with the weights on the side.

Physiological Changes in Silo • The most commonly used silages are corn and sorghum. • Crop should be at 62-68% moisture before ensiling. • If crop is too wet it will not produce lactic acid but butyric acid, causing a sour feed with high nutrient loss. • If it is too dry it will mold easily.

Physiological changes • It takes about 21 days for the fermentation process to complete. • Living cells continue to burn plant sugars, use oxygen, and give off carbon dioxide, water and heat. • Acetic acid is produced early in the process and plant pH changes from 6.0 to 4.2. • After 3 days, the formation of acetic acid slows down and lactic acid is formed.

Physiological changes • Formation of lactic acid continues for about another 2 weeks and the temp decreases. • Bacterial action stops when pH reaches 4. • If conditions are have been right, the silage is now fairly stable, and will remain so for a long period of time. • The ideal temp is 80-100 degrees, if temp is lower butyric acid is formed, causing foul odor and breaking down the protein. • Higher temps cause caramelized silage is formed, it is sweet tobacco smelling, it is higher is palatability but low in nutrient value

Harvesting Crops for Silage • Corn should be harvested at the dough to hard dent stage, 32-38% moisture. • Grasses and legumes should be wilted to below 65% moisture. • Grasses should be ensiled in the early heading stage and legumes at about one tenth bloom. • Small grains are harvested for silage in the boot to early milk stage for best results.

Silages • Grass and Legumes should be chopped at one quarter inch. • Dry matter losses are kept to a minimum when grasses and legumes are stored in the silo at 50-65%.

Adding Dry Matter and Preservatives • Many things are added to silages to reduce moisture, aid in curing and increase palatability. • Dry grain, is added to reduce moisture, however it may not be economically feasible. • Chemicals increase palatability but also may not be financially feasible.

Important other Factors • Rapid filling, even distribution, packing and prompt covering of silages. • Legumes that are higher in protein will spoil quicker. • Grass silage does not keep well in trench or bunker silos. • Corn silage should be chopped to 1/4 -3/8 of an inch. • Corn should be filled quickly and evenly.

Feed Samples for Analysis • Sample must be carefully secured to accurately represent a much larger quantity of feed. • Less than one quart of feed is usually submitted. • There are many was to sample, hand, harvest, core and bulk feed. Moisture content should always be consistent as possible.

Proximate Analysis of Feedstuffs • Feed using chemical and mechanical means is separated into 6 components. • Water content, crude protein with Kjeldahl process, crude fat, crude fiber, minerals, and Nitrogen free extract.

Limitation of Proximate • No indication of palatability, digestibility, toxicity or nutritional value. • Feeding trials with live animals are necessary to determine actual worth of a feed for practical feeding purposes. • Organic components of the feed, crude proteins, amino acids, ether extract and cell wall may vary in individual fees as much as 15% more or less than the table values.

Feed Composition Basis • All feeds contain moisture, depending upon the form fed, time harvested and storage time. • As fed means the data is calculated on the basis of the average amount of moisture found in the feed as it is used on the ranch. • 100% dry matter basis means that the data presented is calculated on the basis of all the moisture removed from the feed.

Van Soest Method • Neutral detergent soluble is lipids, sugars, starches and proteins. • Neutral detergent fiber is the more insoluble material found in the cell wall. • Consists of cellulose, lignin, silica, hemicellulose and some protein. • Acid detergent fiber consists of cellulose, lignin and some silica.

Livestock Nutrition