Unit 5 Forage quality New material, exam 2

What does the consumer (animal) want? Maximum quantity, dry matter/feeding Maximum quality, nutritive value The goal of the producer: Maximum quantity (yield), dry matter/A Stand persistence, perennial stand remains healthy over years Maximum quality, nutritive value

What do you know about forage quality?

nucleus mitochondria chloroplast vacuole Plant Cell plasma membrane cell wall plasmodesmata

Cell contents also called total non-structural carbohydrates (TNC): ProteinsNon-protein nitrogen SugarLipids Starch/fructans Pectin Organic acidsWater soluble vitamins and minerals Cell wall constituents also called structural carbohydrates: HemicelluloseCellulose Fiber-bound proteinLignin Heat damaged proteinLignified N Silica

Photosynthesis produces sugars that become the CHO reserves The sugars Monosaccharides - single benzene ring Glucose Fructose Disaccharides - two benzene rings Sucrose, glucose + fructose Polysaccharides, nonstructural - multiple Starch Fructans

Starch, G-G-(G) n Fructan, G-F-(F) n glucosefructose

Growth uses sugars that are produced during photosynthesis (PSN) in the green tissue of the plant, i.e. leaves and stems Transport through the plant via phloem is sucrose Used for growth, energy source via respiration New plant material Stored Dry weight of plant material that is harvested Stored in area that are not harvested Storage in roots in legumes is starch Storage in stem bases in cool-season grasses is fructan Storage in stem bases in warm-season grasses is starch

Nonstructural sugars Sugarfructan or starch Excess sugar High LAI values Onset of spring growth Immediately after defoliation Low LAI values Onset of winter (polysaccharides)

Structural sugars Sugarfructan or starch Hemicellulose, Cellulose, Lignin

cellulose hemicellulose Figure 1. Cell Wall (Pioneer Manual). ADF NDF secondary wall, inside the cell primary wall, outside of the cell ADL lignin Not correct

cellulose hemicellulose Figure 1.Cell Wall ADF NDF secondary wall, inside the cell thick primary wall, outside of the cell thin ADL lignin correct

Hemicellulose and cellulose Figure 1.Cell Wall secondary wall, inside the cell primary wall, outside of the cell lignin Cellulose and hemicellulose

Cell wall (primary and secondary layers) make up 40-80% of the dry matter of the forage. The primary wall is characterized by being thin and formed while the cell is growing. It has elasticity. It contains hemicellulose and cellulose The secondary wall contains more cellulose and some hemicellulose with lignin in between The digestibility of the cell wall decreases as the amount of lignin increases.

Forage species differ in their proportion of hemicellulose, cellulose, and lignin. Legumes have less hemicellulose compared to temperate grasses. Grasses have 3 to 4 times more. Typical forages have 3-12% lignin, with legumes on the upper end. Warm season grasses have higher % cell wall than cool season grasses

Rumen environment The rumen in large cattle may have a capacity of gal, sheep 1-2 gal. Rumen pH fluid is normally 6 to 7 on a forage diet, may be <6.0 on a concentrate (grain) diet. The rumen is a “fermentation vat”, with bacteria and protozoa active in fermentation. The microbes have the enzymes capable of cellulose and hemicellulose digestion.

Hemicellulose Cellulose Pectin Fructans Starch Glucose Fermentation: VFAs - volatile fatty acids Acetic acid (C2) Propionic acid (C3) Butyric acid (C4) Major source of energy for the animal Methane (CH 4 ) Heat VFAs Nonstructural CHO diets low acetic/propionic ratio Structural CHO diets high acetic/propionic ratio Saliva provides sodium bicarbonate to buffer VFAs

Microbes are obligate anaerobes, will tolerate a low level of O 2. Many species of microbes have been identified. The composition of the diet determines the composition of microbial flora. Cellulose diets (forage) vs starch (concentrate) diets. Rapid change in diets is dangerous. The new diet should be introduced gradually over a period of days, allowing rumen flora to adapt. Acidosis, excess acid, insufficient buffering capacity of the rumen

Microorganisms can synthesize amino acids Ruminants digest the microorganisms in the small intestine, providing the amino acids for animal growth.

Two components of forage quality are: The energy value of each unit of dry matter consumed Chemical composition Digestibility Utilization of digested forage The amount of dry matter the animal will consume, i.e. intake Acceptability Rate of passage Availability

Estimates of Chemical Composition dry matter determination protein analysis fiber relative feed value

Dry matter determination (DM): Is the percentage of the feed that is not water Hard to compare forage samples if they differ in the amount of water DM = % water, at 100 C % water = (before wt - after wt)/before wt

Crude Protein (CP) Includes amino acids and non-protein nitrogen Forage protein contains about 16% N Includes both available and unavailable protein Total nitrogen is measured using Kjeldahl technique CP = %N x 6.25 or %N/0.16

About 90% of the N is in the cell contents Non-protein nitrogen (NPN) includes amino acids, nucleic acids, amides, nitrates Protein represents about 60-80% of the N 70% of the protein in C3 plants is Rubisco, an important enzyme in photosynthesis

Adjusted Crude Protein (ACP) Typically 0-12% of the CP is connected to the fiber portion of the sample Results from excessive heating of the forage Sometimes called insoluble CP The ACP value should be used for balancing rations if ACP is >12%

Detergent Fiber Analysis Developed by Peter Van Soest in the 1960s Separates a sample into two parts Cell solubles, % digestible Detergent fiber, cell wall Hemicellulose, 20-80% digestible Cellulose, 50-90% digestible Lignin, 0-30% digestible

Fig 3. Detergent Procedure to Partition Forages Pioneer Forage Manual Forage Digest with neutral detergent Cell Contents proteins starch sugars organic acids pectin Hemicellulose, Cellulose, Lignin (NDF) insolublesoluble

NDF Neutral Detergent Fiber Remains after treatment with a detergent under neutral (pH=7) conditions Contains hemicellulose, cellulose, and lignin Some of the NDF is digestible Constituents that give bulk to the forage Negatively correlated with dry matter intake Used to estimate dry matter intake (DMI) as a percent of body weight DMI = 120/NDF%

Fig 3. Detergent Procedure to Partition Forages Pioneer Forage Manual Forage Digest with acid detergent HemicelluloseCellulose and Lignin (ADF) Digest with neutral detergent Cell Contents proteins starch sugars organic acids pectin Hemicellulose, Cellulose, Lignin (NDF) insoluble soluble

ADF Acid Detergent Fiber Remains after treatment with a detergent under acid (pH=2) conditions Contains cellulose and lignin Negatively correlated with how digestible a forage may be when fed Used when estimating Percent Total Digestible Nutrients (TDN) Percent Digestible Dry Matter (DDM) Net Energy (NE)

Fig 3. Detergent Procedure to Partition Forages Pioneer Forage Manual Forage Digest with acid detergent HemicelluloseCellulose and Lignin (ADF) Digest with 72% sulfuric acid Cellulose Lignin ADL Digest with neutral detergent Cell Contents proteins starch sugars organic acids pectin Hemicellulose, Cellulose, Lignin (NDF) insoluble soluble

NIRS Analysis Near Infrared Reflectance Spectroscopy Rapid, easy, reproducible, cheaper new method A dry, ground forage sample is exposed to infrared (IR) light, uniform ground sample is critical The reflected IR radiation is converted to electrical energy The energy level corresponds to specific forage quality, good calibration set is critical Same information as “wet chemistry” analysis Good prediction of ADF, NDF, CP, not minerals

Digestibility Measured using bioassays, In situ, or in vivo in the animal, using fistulated animals; digestion trials, apparent dry matter digestibility, (DM intake - DM out)/ DM intake In vitro, in test tube with rumen fluid, outside the animal, IVDMD (in vitro dry matter disappearance) Calculated, Total digestible nutrients (TDN), summation of the digestibility of the different components DDM (digestible dry matter), DDM% = (0.779 x ADF%)

Relative Feed Value (RFV) Combines dry matter intake (DMI) and digestible dry matter (DDM) Is unitless Used to compare the potential of two forages for energy value Does not take into account the protein content of the feed

DMI%(as a % of body wt) = 120 %NDF RFV = %DDM x %DMI 1.29 RFV = 100: NDF=53%, ADF=41%, alfalfa at full bloom All equations in Pioneer Forage Manual DDM% = (0.779 x ADF%)

Forage ADF%NDF% DMI% DDM% RFV A-M Alfalfa hay3040 N-Z Brome hay3563 A-M Cornstalks4368 N-Z Wheat straw5485 DDM% = (0.779 x ADF%) DMI%(as a % of body wt) = 120 %NDF RFV = %DDM x %DMI 1.29