Cymraeg

Feeds and Feeding
Session 5 - Rationing

This resource is suitable to support Level 2 Agriculture courses.

Introduction

Rations for livestock have to be designed to provide the animals with all of the energy and nutrients to be healthy and productive at an affordable price.

  • The energy and protein requirements of livestock will vary with the stage in the production cycle.
    • Image of pigs feeding

    What Affects Ration Change?

    The energy and protein requirements of livestock will vary with the stage in the production cycle for example:

  • There will be times when stock can be fed on grass, or conserved grass, such as silage with no requirement for concentrate feed e.g. dry ewes and suckler cows. Ewes in late pregnancy carrying twins or triplets and high yielding dairy cows will need rations which contain concentrate feeds to ensure that they can consume enough protein and energy.
    • two images - udders and lambs

    There will be times when stock can be fed on grass, or conserved grass, such as silage with no requirement for concentrate feed e.g. dry ewes and suckler cows. Ewes in late pregnancy carrying twins or triplets and high yielding dairy cows will need rations which contain concentrate feeds to ensure that they can consume enough protein and energy.

  • Rations will contain higher or lower energy densities or protein contents to reflect the balance between animal requirement and feed availability.

    • Selection of Feeds for a Ration

    The feeds selected for a ration on a particular farm will depend on the following factors:

    1. Which feeds are available on the farm.

  • This will vary with the time of year. Many farms in Wales will base their rations on fresh grass during the summer, and conserved grass as silage or hay during the winter.
  • Crops may be grown specifically for livestock feed e.g. swedes, turnips, maize for silage. In some areas by-products from crops may be available e.g. straw.
    • Graphic of 3 feeds

    Selection of Feeds for a Ration

    2. The relative price of feeds.

  • Prices of feeds will change for many reasons including the balance between supply and demand. Generally organic feeds are dearer to buy than a similar product that is from a conventional farm. The cost of delivery and the feed value will be factors that are considered when evaluating the price. For example, a wet feed may appear cheap when the fresh weight per tonne is considered, but the price per unit of protein or energy may not be as good.
  • Market reports will allow farmers to compare the cost of energy (pence/MJ) and the cost of protein (pence/gram of digestible crude protein).
    • Graphic of pound sign going up in graph

    Selection of Feeds for a Ration

    3. The feeding system, scale of the enterprise and machinery available

  • Feeds purchased in bags or in small amounts tend to be more expensive than a similar product purchased in bulk. Not all farms will require large amounts of feed, and they may not have the storage facilities or the machinery to handle the feeds easily.
  • Many large farms have considerable amounts of money invested in feeding machinery and storage facilities; this may enable them to save time when feeding the stock, save money when purchasing the feeds, and provide a consistent ration.
    • Graphic of tractor carrying feed

    Selection of Feeds for a Ration

    4. The level of productivity of the animal.

  • If animals are more productive they need more nutrients, and more money may be spent on feeds.
  • As ewes approach lambing time their requirement for energy and protein increases, but their appetite goes down, therefore concentrates are often fed at this time. If the ewes have been scanned they may be split into groups and fed according to the expected time of lambing and the number of lambs.
  • Dairy cows may be fed according to their level of production, and the stage of the lactation.
  • Lambs and growing cattle may be fed according to how fast the farmer wants them to grow e.g. early lambs may be given creep to get them to grow fast so that they can be sold when the prices are high in the spring.
    • Images of cow and calf and ewe and lamb

    Selection of Feeds for a Ration

    5. Rules relating to farm assurance or organic standards.

  • There may be particular rules governing the type of feeds that can be used.
  • e.g. there are limits to the amount of conventional feed that can be fed on an organic farm.
    • Graphic with Pasture for Life, Red Tractor, and Farm Assured Welsh Livestock logos

    Formulating a Ration

    To calculate a ration you need to know:

    1) The size of the animal

    2) The level of production

    graphic of cow with weighing scales overlayed, and graphic of bottles of milk

    DMI and ME requirement

    From this information you can determine:

  • The appetite (how much dry matter it will eat)
  • Energy (ME) requirement and the protein requirement.
  • Silage analysis or feed analysis tables can be used to determine the amount of ME, protein and minerals available in the feeds and to calculate a ration.
    • Image of cow

    Computer Programmes for Rations

    Rations are now calculated using computer programs as these allow factors such as feed price to be included in the calculations and allow a large number of feeds to be considered for a mix; however it is possible to calculate simple rations fairly quickly.

  • The cheapest ration is described as the least cost ration.
    • Graphic of computer screen

    Ration Calculation

    Simple rations using a balance of a roughage and a concentrate feed can be calculated using Pearson’s square.

  • For the calculated ration to work the animal must be able to eat to appetite.
    • Graphic showing Pearson's Square

    Ration Calculation

    Task

  • Calculate a ration to feed a 70Kg ewe, carrying twins at lambing. The ewe is housed, and the main bulk feed available on the farm is silage.
    • Graphic showing ewe outline with 2 lamb outlines inside

    Step by Step Guide

    Step 1

  • Look up the sheep’s daily requirements for protein and Metabolisable Energy (ME).
  • Energy required (ME) 16.5 MJ Digestible crude protein (DCP) 132g.
    • Graphic showing text: 'Step By Step - Step 1'

    Step by Step Guide

    Step 2

  • Look up the amount of dry matter the ewe can eat in a day (appetite).
  • Appetite 1.33 Kg per day of dry matter
    • Graphic showing text: 'Step By Step - Step 2'

    Step by Step Guide

    Step 3

  • Calculate the average amount of energy needed in each kilogram of dry matter.
  • Energy needed by the ewe = Amount of energy needed per kg of DM Appetite.
  • Energy 16.5MJ = 12.4 MJ/Kg of dry matter.
  • 16.5 / 12.4 = 1.33Kg
  • 1.33 Kg.
    • Graphic showing text: 'Step By Step - Step 3'

    Step by Step Guide

    Step 4

  • Select suitable feeds for the ration. For the calculation to work there must be one with an energy value above the average that has been calculated in step three, and one with an energy value below the average.
  • Two possible feeds are shown below; the information was taken from a table of feed values.
  • Silage - ME (energy) 12.0 MJ/kg DM DCP (protein) 125 g/kg DM Dry matter 25%
  • Compound - ME (energy) 12.9 MJ/kg Dry Matter = 86% DCP (protein) 140 g/kg
    • Graphic showing text: 'Step By Step - Step 4'

    Step by Step Guide

    Step 5

  • Balance the amount of each feed to be used, using Pearson’s square.
    • Graphic showing Pearson's Square

    These figures can be used to calculate the ratio of the two feeds in the ration.

    Silage

  • Figure opposite X Appetite = 0.5 X 1.33kg = 0.73kg silage DM
    Total 0.9

    • Compound

  • Figure opposite X Appetite = 0.4 X 1.33kg = 0.6kg compound DM
    Total 0.9
  • This would give a total of 0.73kg +0.6 kg = 1.33kg of dry matter in the ration (this matches the sheep’s appetite).

    • Step by Step Guide

    Step 6

    The figures should be checked to ensure the energy and protein levels are correct.

    Energy Level:

    Silage: dry matter X energy per Kg = amount of energy from the silage:

  • 0.73kg X 12.0 MJ/Kg = 8.8 MJ

    • Compound: dry matter X energy per Kg = amount of energy from the compound:

  • 0.6kg X 12.9 MJ/Kg = 7.7MJ

    • Therefore the total ME of the ration is 8.8MJ + 7.7MJ = 16.5MJ

    Graphic showing text: 'Step By Step - Step 6'

    Step by Step Guide

    Step 6

    The figures should be checked to ensure the energy and protein levels are correct.

    Protein Level:

    Silage: dry matter X protein per Kg = amount of protein from the silage

  • 0.73kg X 125g/Kg = 91g

    • Compound: dry matter X protein per Kg = amount of protein in the compound

  • 0.6kg X 140g/Kg = 84g

    • Therefore the total digestible crude protein content of the ration is 175g; this is above the requirement of 132g per day.

    Step by Step Guide

    Step 7

    Convert the amounts of feed to fresh weight.

    Quantity of feed X 100 = Fresh weight (Kg) Dry matter percentage

    Silage: 0.73Kg X 100 = 2.9kg of fresh silage

  • 25

    • Compound: 0.6 Kg X 100 = 0.7Kg of compound feed

  • 86
    • Graphic showing text: 'Step By Step - Step 7'

    Points to Remember When Calculating Rations

    Always check that the answer is sensible.

  • Feed quality varies e.g. not all of the silage made on the farm will have exactly the same analysis.
  • Rations are calculated using dry matter figures; they must be converted to fresh weight before the actual amount to feed is known.
  • There can be significant variation within a group of livestock (e.g. size, level of production).
  • Other characteristics of the feeds such as the type of protein supplied, the levels of sugar, starch and fibre, and mineral levels will need to be considered.
    • Graphic of human head with cogs overlayed and text 'Points To Remember'
    Back to Menu Next Session ▶