GrazFeed Release Notes

GrazFeed changes

Version 5.0.9 – Dec 2023


  1. Added a new output table in the brief summary display showing the supplement proportions as fed.
  2. Bug fixes for the user interface on the Mac OSX version.

Version 5.0.8 – Sep 2021

Animal model

  1. Peak lactation for dairy cattle has been modified. Higher milk production when no calves at foot. This has required some additional changes to the animal parameters. Old external parameter files will need their structure changed to match the new configuration.
  2. Peak intake parameters during lactation for sheep have been corrected to follow technical spec. This has increased intake when lactating.

Changes to GrazFeed for version 5.0.7 – August 2016


  1. Corrected a bug in the least-cost ration formulator that would cause it to falsely assume that no supplement was required.

Changes to GrazFeed for version 5.0.6 – May 2016

Animal model

  1. Fixed a bug which was leading to cross-bred young incorrectly using parameters of their female parent’s breed.
  2. Fixed a buf affecting animal performance when supplement was offered in conjunction with rotational grazing.


  1. Fixed bug in General Responses plots, in which the initial state of the model was not begin properly restored, leading to inconsistent results.
  2. Corrected a bug in the setting of maximum value for time since mating of sheep.
  3. Fixed a user registration problem on newer versions of Windows.


Changes to GrazFeed for version 5.0.5 – March 2014

Animal model

  1. Corrected a bug with the ordering of the protein degradability array in the GrazFeed API.


  1. Allow weaners to be pregnant.


Changes to GrazFeed for version 5.0.4 – March 2013 

Animal model

  1. The reduction of potential intake when RDP is less than the calculated requirement has been decreased for Bos indicus cattle.
  2. Lactating animals are no longer excluded from the restriction of potential intake when relative condition is greater than 1.0.
  3. The function relating protein degradability in herbage and roughages to dry matter digestibility has been changed, from “DMD + 0.1” to “Min(0.84 * DMD + 0.33, 0.99)”.
  4. Wool growth parameters were altered to compensate for changes resulting from modification of the protein degradability function.


  1. Corrected a bug which sometimes caused user-entered sheep ages to not be restored correctly.
  2. When there is no pasture available, a zero level is no longer inserted as a supplement feeding level.
  3. Corrected a bug in which user-modified values of the protein content of the herbage on offer were not being displayed correctly in the output tables.
  4. Corrected a problem in which changing green protein values would cause a change in dead protein values, and vice versa.
  5. The default location of the GrazFeed.ini file has been changed to allow for correct operation with non-administrator accounts on Vista and Windows 7.
  6. Links in help files for SheepExplorer and CattleExplorer downloads have been updated.
  7. Positioning of dialog windows has been made more consistent.
  8. Size and position of main window is now retained across sessions.


Changes to GrazFeed for version 5.0.3 – July 2010

New features

  1. Support was added for ewes bearing triplet lambs.

Animal model

  1. The relationship between metabolisable energy and digestibility of roughages was modified.


  1. Now uses the currency symbol specified by the current Windows locale.
  2. Characters not permitted in Windows file names are now automatically changed to underscores in the simulation name.
  3. Corrected a bug which caused user-entered pasture values to sometimes be automatically rounded to slightly different values.
  4. Corrected a problem with display of context help when F1 is pressed.
  5. Corrected a bug in which changing the breed selection could cause inappropriate default weights to appear on the Animals tab.


Changes to GrazFeed for version 5.0.2 – February 2009
Animal model

  1. Corrected a fault in the calculation of lower critical temperature of lambs.


  1. Corrected a bug which caused values for “Time since mating” and “Distance walked” for cattle to inappropriately revert to default values.

Changes to GrazFeed for version 5.0.1 – August 2008
New features

  1. Added a facility for the calculation of least-cost ration mixtures.
  2. Translated the interface and help into the Spanish language.

Animal model

  1. Corrected a fault in the calculation of supplement intake under intensive grazing.
  2. Modified to allow mating of 1-2 year-old heifers.


  1. Corrected a fault with clearing the “intensive grazing” setting.
  2. Corrected a fault in the display of ME/DM values for a roughage when displaying as MCal.
  3. Improved handling of scenarios with no available herbage.
  4. Reordered the columns within the “brief results” output.
  5. All costs are now reported in $, rather than a combination of $ and c.
  6. Corrected a fault in the relationship between DMD and M/D for urea.
  7. Corrected a fault which could cause supplement cost information to be lost when a new supplement was added.
  8. Corrected installation problems which could prevent program execution under Windows Vista.

Changes to GrazFeed for version 4.2.1 – June 2007

  1. Several memory leaks eliminated.
  2. Corrected problems with the handling of user-defined supplements.
  3. Default values for prices updated to better reflect current market conditions.
  4. Fixed minor problems with dialogs when run under Windows Vista.

Changes to GrazFeed for version 4.2.0 – December 2006

  1. An Automation interface has been added to provide third-party applications with access to the GrazFeed model engine. Software developers may refer to the file ‘GrazFeed Model API.rtf’ in the GrazFeed application directory for a detailed description of this interface.
  2. Fishmeal has been removed from the list of supplementary feeds.

Changes to GrazFeed for version 4.1.15 – September 2006
Animal model

  1. An error that resulted in incorrect predictions of foetal weight gain on diets deficient in rumen-degraded protein has been corrected.
  2. The depressing effect of high body condition on potential intake has been increased.

Changes to GrazFeed for version 4.1.14 – Nov 2005
Animal model

  1. Following a further examination of data reviewed by Richard Stockdale, the effects of lactation and protein content on substitution rate (referred to in the changes for 4.1.13 below) have now been removed.


  1. Limits on the mature weight of a bull on the Females screen work properly.
  2. The default value for the dry matter digestibility of oats on the Concentrates screen has been restored to 73%. Users of input files from earlier versions may need to restore this value through the Default Composition button.
  3. The Default Composition button on the Concentrates screen is now working correctly.
  4. Table 5 is now shown when the addition of a supplement causes a decline in production for Target feeding.

Changes to GrazFeed for version 4.1.13 – May 2005
Animal model

  1. The algorithms for computing the effects of lactation and high protein concentration in the supplement on the substitution rate when supplements are offered to grazing animals have been changed, to avoid the possibility of the total intake exceeding the intake limit of the animal.
  2. The effect of high body condition on potential intake, which previously applied only to mature animals, now applies at all stages of maturity.

Changes to GrazFeed for version 4.1.12 – April 2005
Animal model

  1. Users that are using a non Australian locale can select measurement units from the options | units dialog. Units are now independent of locale.
  2. On the supplements tab, the computing of the total supplement percentage exhibited rounding errors using certain values. Fixed. Calculation for 100% uses values as displayed.
  3. Upper limit for sheep SRW increased to 120 kg.
  4. Fixed the problem when the Default Composition dialog was used to set the composition of a chosen ingredient. It now only changes the ingredients you select.
  5. Fixed Access Violation when using supplement for target weight gain.

Changes to GrazFeed for version 4.1.11 – December 2004
Animal model

  1. A change to the prediction of the composition of weight change has the effect of restoring the values that were predicted before the change made in v.4.1.8 to the normal weight of immature animals that are not gaining weight.
  2. The persistence of an increased intake limit for mothers of early-weaned young is now working effectively.
  3. The prediction of the intake of silage required to meet a Target option has been corrected to deal with silage of low dry matter percentage.


  1. Two faults in the Default key on the Pasture2 screen have been corrected
    • If the user was using a saved file in which the distribution had already been changed and then made further changes in the current run, pressing the Default key restored the saved distribution, not the ‘original’ default distribution.
    • If dead pasture was set at zero, so that the distribution represented only the green herbage, then the Default button was inactive.
  2. A fault in the plotting routines that caused the printing of a blank rectangle when the Display button was pressed on the General Responses dialog, has be corrected.
  3. A non-functioning Page Setup option has been deleted.

Changes to GrazFeed for version 4.1.10 – August 2004
Animal model

  1. New formulation of functions for predicting changes during gestation, with appropriate changes to parameters, but no change to predicted values.
  2. The standard birth weight of cattle changed from 35 to 40 kg, to match ARC (1980)
  3. A single equation now used for all supplements for predicting efficiency of use of ME for weight gain (kg).
  4. The effect of season on kg predicted for herbage diet now decreases with decreasing M/D.
  5. Endogenous faecal protein now estimated as a function of dry matter intake rather than protein intake..
  6. The energy content of clean wool changed from 4.5 to 4.7 MJ/g
  7. The conversion of methane energy to weight changed from 18.52 to 18.09 g/MJ


  1. Correction of errors in the naming and entry of a new feed
  2. Correction to the selection of breed type when switching to sheep from cattle low on the list
  3. The reminder message about a change to feed composition now appears only once

September 2003
Animal model

  1. The effect of pasture height on the prediction of relative intake has been modified so that there is a better balance between the height and mass of the herbage.
  2. The effect of legume proportion on relative intake now decreases with the mass of herbage so that there is little effect when little herbage is available.


  1. Correction of an error in the predicted digestibility of a supplement when the user changes the ME/DM value
  2. A change to an animal weight is now correctly saved when an input file is saved.
  3. The acceptable range of feeding levels for cattle was increased earlier, to accommodate silage feeding, but the change was not working correctly. This has been rectified.
  4. The Comments have been adjusted so that they apply more correctly to animals off pasture.
  5. The selection – copy and paste from the output works properly now.

October 2002
Changes to animal model

  1. Normal weight in immature animals in now predicted to increase slowly, even if actual weight is static or falling.
  2. The time of peak intake in lactating beef cows has been reduced to 62 days after parturition.
  3. The effect of lactation on potential intake now persists for up to 2 months after the end of lactation. This will give more realistic results when young are weaned early.
  4. The extent to which lactating animals can achieve their potential milk production, at the expense of body tissue, is now directly related to their current body condition.
  5. The energy and protein content of bodyweight change in mature animals now depend on their body condition.
  6. The effect of lactation in reducing substitution rate when supplements are offered has been increased.
  7. The prediction of ME/DM for concentrate feeds has been improved through the use of more recent data.
  8. The prediction of digestibility of undegraded protein in concentrate feeds has been improved by inclusion of acid detergent insoluble protein (ADIP) values in feed composition.
  9. Distance from pasture to milking shed has been included in the calculation of maintenance requirement for dairy cows, with the assumption that the specified slope of land applies to this distance.
  10. The energy cost of eating for lower quality feed has been reduced.
  11. The energy cost of walking for intensively grazed animals has been reduced.
  12. Feeds with no energy or no protein (e.g. urea, tallow) can now be offered as the sole supplement without causing errors.
  13. The effect of feeding whole grains to cattle has been revised.

Changes to interface

  1. Changes to Pasture 1 screen are accepted by the program, without the user displaying Pasture 2 (this was only partially corrected earlier).
  2. An extra tab on the Supplements screen restores the default composition of any selected feed
  3. A selected feed can be deleted from the list.
  4. A warning has been included if high oil (or fat) supplements are selected.
  5. ADIP has been added to the composition list on the More Feeds screen, for its role in predicting the digestibility of undegraded protein.
  6. The fleece description on Breed screen has been changed to ‘the average weight of fleece’, with an accompanying reduction in the default values.
  7. The standard reference weight of males used for breeding can now be changed on the Females screen.
  8. Females screen now includes fields for mature weight of male, information about previous lactation (if appropriate) and, for dairy cows, distance between paddock and shed.
  9. Feeding levels allowed on Feeding screen have a wider range, to accommodate silage feeding to cattle.
  10. Milk yields for dairy cows are reported in volume as well as weight.
  11. Energy balance of pregnant and/or lactating females now shown as change in condition score, as well as in predicted weight change.