Unit 2 evaluating feedstuffs for farm livestock
Download
1 / 27

Unit 2: Evaluating Feedstuffs for Farm Livestock - PowerPoint PPT Presentation


  • 265 Views
  • Uploaded on

Unit 2: Evaluating Feedstuffs for Farm Livestock. Unit 2: Evaluating Feedstuffs for Farm Livestock. Unit 2 Objectives: Understanding of methods used to determine nutrient composition of feeds Knowledge of sample collection methods Identify and communicate how feed samples are reported

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Unit 2: Evaluating Feedstuffs for Farm Livestock' - andrew


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Unit 2 evaluating feedstuffs for farm livestock1
Unit 2: Evaluating Feedstuffs for Farm Livestock

  • Unit 2 Objectives:

    • Understanding of methods used to determine nutrient composition of feeds

    • Knowledge of sample collection methods

    • Identify and communicate how feed samples are reported

    • Comprehension of how feedstuff digestibility is determined

    • Understand various energy measurements and how they are used

    • Physical and economical evaluation of feeds


Unit 2 evaluating feedstuffs for farm livestock2
Unit 2: Evaluating Feedstuffs for Farm Livestock

  • Analytical Methods for Nutrient Composition

    • Three general types of methods can be used to determine effect of feedstuffs

      • Chemical procedures

        • Titration, colorimetry, etc.

      • Biological procedures

        • Feedstuff tested by a live animal (rat, chick)

        • More accurate

        • Much more tedious and expensive


Unit 2 evaluating feedstuffs for farm livestock3
Unit 2: Evaluating Feedstuffs for Farm Livestock

  • Microbiological procedures

    • Tested w/ isolated bacteria

  • Obtaining Samples for Analysis

    • Key to reliable feed nutrient evaluation is a representative sample

    • Identification

      • Thoroughly identify the feed tested

      • What might we include in our identification?

    • Sampling

      • Grains/Mixed Feeds

        • Sacked feeds – 2 samples/sack, 5-7 sacks, handful each


  • Unit 2 evaluating feedstuffs for farm livestock4
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Bulk Feeds – 12 to 15 samples, widely separate locations for sampling (while delivered or fed, if possible)

    • Mix samples in a clean pail, make sure feed doesn’t separate, send a 1 or 2lb. sample to the lab

  • Hay

    • Use a core sampler

    • Take a 12’ – 15” core sample that will include stem and leaves

    • 12 – 15 samples are needed to be accurate (1/bale)

    • Try to get to middle of the stack if possible

    • “Grab” Samples can be used, but accuracy is variable


  • Unit 2 evaluating feedstuffs for farm livestock5
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Haylage or Silage

      • Upright silos – collect during feedout, several small samples, mix together for one composite

      • Pit/Bunker silos – 4-5 grab samples from a fresh face, do not collect spoiled material, do not collect within 12”-18” from edge

      • Freeze if you are collecting over multiple days

      • Refrigerate if you can’t mail immediately (what happens if you don’t do this?)

    • Harvest Sampling

      • Not recommended for any feed <30% DM

      • Same methods as discussed prior

      • 12-15 samples, mix for one composite

      • Mark different fields as feed is stored (plastic marker, oats, etc.)


    Unit 2 evaluating feedstuffs for farm livestock6
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • General

      • Not beneficial unless you are going to use in designing a feeding program

      • Three benefits to using sampling for proper balance of feedstuffs – 1) minimize protein supplementation and reduce cost, 2) can properly balance if a nutrient is being underfed, 3) can confirm that a factor other than feed is limiting production

  • Proximate Analysis

    • Most generally used chemical analysis to describe nutrient composition of feeds


  • Unit 2 evaluating feedstuffs for farm livestock7
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Dry Matter (DM)

      • How do we determine DM content of a feedstuff?

      • Can we do this ourselves?

      • What is the benefit of knowing the DM content?

    • Ash (minerals)

      • Burned sample that removes all other nutrients

      • Only inorganic residue remains

      • May not be 100% accurate

    • Crude Protein (CP)

      • Digest to N through chemical process (Kjeldahl process)

      • How do we determine CP content from N concentration?

      • Does not distinguish between forms of N


    Unit 2 evaluating feedstuffs for farm livestock8
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Ether Extract (Fat)

      • Use ether to extract fat contents for 4 hrs

      • Loss of wt = fat content

      • Includes some “fats” that are of no use to animals, so may not be 100% accurate

    • CHO

      • Crude Fiber (CF) – remove water & fat; then through chemical rxn. to remove protein, sugar, and starch; leaves cellulose, lignin, and minerals; (how are the minerals removed?)

      • Nitrogen-Free Extract (NFE) – sugars and starches (maybe some hemicellulose & lignin); not determined by an analysis; 100% - water, ash, protein, fiber, fat


    Unit 2 evaluating feedstuffs for farm livestock9
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • The Van Soest Method

      • Focuses on forage fiber

      • Divides fiber into digestible and indigestible fractions

      • Extraction w/ detergents

      • Predicts intake – NDF – index of gut fill

      • Predicts digestibility – ADF – indicates forage digestibility

      • Heat damaged forages – can help determine the amount of protein unavailable in feedstuff. What level of unavailable begins to cause problems?


    Unit 2 evaluating feedstuffs for farm livestock10
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Near Infrared Reflectance Spectroscopy

      • Ability to sample quickly w/ little preparation (grinding); only uses one sample

        • Can be completed in <3 min.

        • Analyze multiple components in one operation

      • Measurements done by absorption/reflection of light

      • Not accurate for minerals

      • Expensive equipment, must be calibrated correctly

      • Wet-chemistry analysis is more accurate

      • Inexpensive


    Unit 2 evaluating feedstuffs for farm livestock11
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Determination of Vitamins

      • No routine analysis available to determine vit content

      • Assays can be ordered to determine specific vitamins, if needed

    • Determination of Energy

      • Bomb Calorimeter

      • Sample is burned in an oxygen atmosphere

      • Liberated heat raises the temp of water surrounding the devise

        • This temp increase is the basis for determining the energy concentration

        • 1 cal heat required to raise 1g water 1º C


    Unit 2 evaluating feedstuffs for farm livestock12
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Nutrient Expression

      • DM basis

        • Most accurate/common way to express nutrient levels

        • Levels the playing field to compare feeds

      • As-Fed basis

        • Amount of nutrients contained in a feed as the animal would consume it

      • Air-Dry basis

        • Assumed to be ~90% DM


    Unit 2 evaluating feedstuffs for farm livestock13
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Let’s practice some conversions

      • Thumb rules

        • Nutrient concentration should increase when converting to DM basis

        • Wt. will decrease on DM basis

  • Feeding Trials

    • Can give information as to acceptance and performance of a feed

    • Doesn’t tell why a feed performed the way it did


  • Unit 2 evaluating feedstuffs for farm livestock14
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Digestion or Metabolism Trial

      • Weakness of chemical analysis is that is doesn’t take into account digestibility very accurately

      • Steps of a digestion trial

        • Proximate feed analysis to know what you start w/

        • Feed a measured amount of feed, or feed at constant rate

        • Collect fecal matter

        • Proximate analysis on feces

        • Difference is the apparent digestibility of the feed


    Unit 2 evaluating feedstuffs for farm livestock15
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Can use markers or indicators to identify feeds

    • Testing can be done in metabolism stalls where the animal is somewhat confined

      • Attached to collection instruments for feces and/or urine

    • Usually done in 2 phases

      • Preliminary phase

        • Frees digestive tract of any other types of feeds

        • Animal gets accustomed to the process and feed

        • 3-5d in pigs, 8-10d in ruminants


    Unit 2 evaluating feedstuffs for farm livestock16
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Collection phase

      • When feed and fecal collections are measured

  • What are some of the chances for error in this system?

  • Measures of Feedstuff Energy

    • Total Digestible Nutrients (TDN)

      • General, calculated amount

      • Does not account for important losses of digestion

      • Can be expressed as lbs., %, or kg


  • Unit 2 evaluating feedstuffs for farm livestock17
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Can be extremely variable/inaccurate (usually overestimate)

      • 1lb. TDN from 1.2 lbs. corn = 1.2 Mcal NE

      • 1lb. TDN from 2.1 lbs. hay = 1.0 Mcal NE

      • 1lb. TDN from 2.4 lbs. poor hay = .8 Mcal NE

  • Nutrient Partitioning in Digestion & Metabolism

    • Energy Units

      • Calorie = amount of heat needed to raise 1g water 1ºC

      • Kilocalorie = 1000 calories

      • Megacalorie = 1000 kcal, or 1,000,000 calories (a.k.a. therm)


  • Unit 2 evaluating feedstuffs for farm livestock18
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Gross Energy (GE)

      • Total potential energy of a feedstuff consumed

      • Determined in a bomb calorimeter

    • Fecal Energy (FE)

      • Undigested residue that passes through the GI

      • Can be collected and tested same method as above

    • Digestible Energy (DE)

      • DE = GE – FE

      • Takes account of some losses during digestion

    • Gasseous Products of Digestion (GPD)

      • Combustible gasses that escape the body during digestion & absorption

      • Mostly methane; some H, CO, acetone, etc.


    Unit 2 evaluating feedstuffs for farm livestock19
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Most common in ruminants

    • Hard to measure accurately

  • Urinary Energy (UE)

    • Includes materials that result directly from the digestion/absorption/enzymatic processes

    • Many endogenous sources as well

  • Metabolizable Energy (ME)

    • ME = DE – UE – GPD

    • More accurate measure of nutritive value than DE and TDN

    • Easy to determine in nonruminants because of the lack of GPD


  • Unit 2 evaluating feedstuffs for farm livestock20
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Heat Increment (HI)

      • Increase in heat production following feed consumption

      • Caused by the heats of fermentation, and heats of nutrient metabolism

      • Energy is wasted unless the environmental temperature is below the animal’s critical temperature zone

      • If it is used for temperature regulation, becomes part of NEm

    • Net Energy (NE)

      • NE = ME – HI

      • Amount of energy used for maintenance only, or for maintenance and production purposes

      • Function should be stated clearly when reporting/evaluating NE


    Unit 2 evaluating feedstuffs for farm livestock21
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • NEm (NE for Maintenance)

      • Part of total NE needed to keep animal in energy equilibrium

      • No gain/loss of energy in body tissue

      • Basal Metabolism – energy needed to maintain basic vital cellular activity

      • Energy of Voluntary Activity – energy needed for basic movement to obtain food, water, lying down, etc.

      • Heat to keep body warm – additional heat needed when environmental temp < animal’s critical temperature


    Unit 2 evaluating feedstuffs for farm livestock22
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Heat to keep body cool – extra energy expended when environmental temp > animal’s thermo neutral zone

  • NEp (NE Production)

    • Additional energy required above NEm

    • What would be considered production?

    • NEl, NEg

  • Energy in Beef Cattle

    • This system can be used to accurately predict energy needs for wt. gain under normal conditions

    • Make adjustments for abnormal conditions

    • See tables 2-3, 2-4, and 2-5 for reference

    • We will discuss further later in the semester


  • Unit 2 evaluating feedstuffs for farm livestock23
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Energy in Dairy Cattle

      • NE values are much more accurate than any other system

      • Evaluate NEm, NEg, and NEl

        • NEl – includes energy requirements for pregnancy, reproduction, and milk production

        • NEl – most often used component in ration formulation and evaluation

    • Energy in Swine

      • Generally use ME or DE as their evaluating tools

      • Will eat to energy requirements if feed ad libitum

      • Will cover further later


    Unit 2 evaluating feedstuffs for farm livestock24
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Physical Evaluation of Feedstuffs

      • Eye Appraisal

        • Used mostly w/ forages

        • Type

        • Color

        • % of leaves

        • Weed contamination

        • Spoilage

      • Palatability


    Unit 2 evaluating feedstuffs for farm livestock25
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Factors Affecting Value

      • Soil fertility

      • Growing conditions

      • Harvesting

        • Stage of maturity

        • Losses

      • Processing & Storage

  • Evaluating Feeds Cost/Unit of Nutrient

    • Cost of feed/unit wt. divided by unit wt. * % nutrient concentration

    • Examples


  • Unit 2 evaluating feedstuffs for farm livestock26
    Unit 2: Evaluating Feedstuffs for Farm Livestock

    • Unit 2 Assignment:

      • Review Problem Solving Questions

        • 1-5

        • Take your time!!!!


    ad