Beef Cattle Test Period Feeding and Test Arrangements

3.8 Test period feeding and test arrangements

Feed intake

Recording feed intake and the calculation of EBV’s for feed conversion efficiency or Net Feed Efficiency is a goal of many breeding programmes. Clearly defined procedures are a prerequisite in the recording of feed intakes and feed efficiencies. The ultimate objective, however, is to generate EBVs having removed non-genetic variation as much as is possible. Standardizing the test procedures within and between locations will reduce non-genetic variation, and with adequate genetic linkages between tests centres, data from different tests both in time and location can be used for estimating BVs.

Feed efficiency

Efficiency of gain in beef production can be defined as the ratio of nutrient input to beef output. It is normally expressed as the kg of feed consumed per kg of live weight gain. However, the definition of feed conversion efficiency needs to be clearly defined for any particular animal recording scheme. Test animals may be fed in varying forms. The ration may be a fully formulated to include roughage and concentrate and fed in cube or loose form. Alternatively, the test animals may be fed with a standard ration supplemented with some form of roughage such as hay or straw. The nutritional contribution of the roughage element may not in some efficiency tests be included in the calculations. Feed consumed may also be expressed in units of dry matter. This will be important where the dry matter content of the ration may vary. Beef output is normally recorded as the total live animal gain. Carcass gain for example may be an alternative measure of beef output.

Recommendations:

1. Nutrition of test animals and definition of beef output should be clearly detailed in the test description.
2. A standardised feeding regime should be adopted which minimizes dry matter variation in the ration fed within and over the tests.

Testing facilities

Feed conversion efficiency recording may be undertaken on farm or in a central test station. The test facilities should be approved in respect of satisfying the minimum standards for such tests and should be monitored from time to time to ensure compliance with these minimum standards. Any modifications of the testing procedures of facilities should be notified to the body responsible for genetic evaluation.

Age and age range of test group

It is desirable that the tests be conducted earlier in the animals’ life to minimize pre-test non-genetic effects. The range in age within a contemporary group should be kept as low as possible. However, for many reasons such as the population size of the breed and birth pattern through the year, it may not be feasible to set a very restrictive age range within a contemporary group. It is recommended that the age range within the contemporary group should not exceed 90 days.

The age over which a feed conversion efficiency determination is made varies considerably between test programmes being normally influenced by production systems. The test may commence soon after birth and continue until the later stages of their growth phase which would normally not extend to greater than two years of age. As the test can be expensive to run, a more restricted test period is normally conducted to facilitate the testing of larger numbers of animals and to minimise costs.

Sex

Bulls, steers or heifers may be tested. Where resources are limited it is recommended that bulls only should be tested, especially at Central Test facilities.

Length of test period

Most feed conversion efficiency tests begin after weaning at about six months of age and should be sufficiently long to facilitate an accurate estimation of feed conversion efficiency or net feed efficiency. The test period should provide for a sufficient adjustment period to allow any pre-test environmental effects to be minimised and to ensure that all animals have adjusted to the conditions and the diet.

Recommendation for the test period

It is recommended that the minimum period over which feed conversion efficiency should be determined is at least 60 days together with an adjustment period of at least 21 days.

Pre-test treatment

Animals destined for entry to a performance test station should be identified in sufficient time to facilitate all of the necessary health tests to be completed. Animals entered for feed conversion efficiency evaluation should not be given any special treatment prior to entry but should be fed on a normal plane of nutrition. They should have been introduced to concentrate feeding and be weaned in sufficient time such that the stress on entering the performance test station is minimized and they can be confidently expected to adapt to the test conditions within the adjustment period.

Animal health

All animals within a test shall be subjected to identical health treatments.

All animals entering a test should receive standard health treatments that allow each animal to achieve its potential growth performance in that environment.

Records of any remedial health treatments administered to individual animals on test should be maintained.

this is a test anchor

Withdrawal of animals from test

Where an animal on test has encountered any condition or circumstance, which has had a significant influence on its performance and for which there is insufficient time for the animal to recover, then such animals should be withdrawn from test.

Allocating animals to groups

A “group” may consist of any number of animals in individual pens. These pens should be adjacent to each other and have the same physical environment.

The test facilities under which feed conversion efficiency determinations are made can vary considerably. Test facilities designs include:

1. Individual pens.
2. Group pens of similar size with individual feed boxes.
3. Group penning with automated feed stations.

Where an animal is temporarily withdrawn from a pen for any reason, it should upon recovery be returned to the same pen if possible.

Recommendation

In the case of individual penning, all animals should be randomly allocated to the pens. Where animals are group penned, it will normally be necessary for management reasons to assign animals to pens based on animal size. These groups should be randomly assigned to the pens.

All animals in the same test must be fed and maintained under similar physical conditions, and must be fed a ration containing ingredients from the same batch.

Feeding regimes and rations

A well-organised feeding system using reliable equipment is essential. Variation in ration and feeding procedures is a significant source of variation between contemporary groups and test centres. Feeding systems vary from simple manually based systems where feed is manually weighed, recorded and dispensed to varying levels of automation including mechanically dispensed to fully computer controlled systems where feed is dispensed under full control to electronically identified animals kept in group pens.

Many test programmes calculate feed conversion efficiency on the basis of ad-libitum feeding. Some evaluation schemes determine feed conversion efficiency based on a restricted level of feeding which is set to achieve a pre-determined level of performance for the group.

Such systems need careful monitoring to ensure that the average performance targets are being attained. Where ad-libitum feeding is being practised, the level of feeding given to the animals should be increased to appetite as soon as possible after the beginning of the test.

In the event of a mechanical failure or any disruption to the feeding system, alternative procedures should be in place to enable all cattle to have access to their normal allocation of ration within 24 hours. If for any reason the feed dispensed on any day cannot be accurately weighed or recorded then that days data must be examined and appropriate adjustments made to the database records. Where feed intake for a day is lost the estimated feed intake for that day should be based on the average intake of the previous 7 days. Automated dispensing systems should be monitored to ensure that feeding levels are being achieved and animals are not reluctant to use the equipment.

The dispensing and recording systems should be checked on a routine basis to ensure the accuracy of all recorded data.

Recommendation

The feeding system used must incorporate accurate measurement and recording of daily individual animal feed intake.

Feeding

A balanced ration appropriate to the biological needs of the animal should be fed in a form which minimises any ingredient selection by the test animal. The ration formulation may change in the course of the test as the nutritional needs of the animal change. All animals within the contemporary group should be fed the same ration. Feeding of roughage may not be a requirement depending on the ration formulation. It may be fed as an aid to rumen function. Access to roughage should be controlled in order to avoid interference with ration intake. Roughage in such quantities as are required to maintain good rumen function should be fed. The pen construction and bedding material should be such as not to interfere with the ration or roughage consumption of the test animals.

Commercially available feed additives or supplements may be included in a ration to minimise health risks, or to ensure that the ration meets the minimum standards for metabolisable energy and crude protein, provided they are included within the manufacturers recommendations and to accepted industry standards.

Recommendations

Consignments of ration should be sampled and analysed on a random basis by an approved feed analytical service to ensure that the ration satisfies the pre-defined specification.

Where more than one test centre is involved in a joint evaluation, the specification of the ration fed should, as far as is possible, be similar. Care should be taken to ensure the ration is suitable for the class of stock.

It is strongly recommended that feed analyses performed before the commencement of test are conducted in sufficient time to modify the intended ration if there is a risk that the ration could fall outside the stipulated levels and cause the data generated to be rejected.

Adjustment period

A sufficiently long adjustment period is necessary in order to allow animals in the test to adjust to the test conditions. In ad-libitum tests the intake of animals should be gradually increased during this period until the animals are eating to appetite. Assessments should be made during this period to determine intake level as a proportion of theoretical intake potential of the animal.

Recommendation

A minimum of 21 days should be provided to facilitate full adjustment to the station conditions.

Data recording

Comprehensive and accurate data recording systems should be established. Details should be recorded in respect of the following.

The individual test details

As a minimum, this should include:

1. Station ID where a number of test centres are involved.
2. Test year.
3. Test number.
4. Test type.
5. Date start (beginning of adaptation period).
6. Date start of test for feed conversion efficiency.
7. Date end of test.

Animals within the test

1. ID number of station.
2. Test year.
3. Test number.
4. Animal ID.
5. Station working number of animal if different from the permanent ID.
6. Pen number.

Intake details of animals on test

The recording of intake details is determined to some degree by the feeding procedures used. With computer based fully automated systems it is possible to record daily feed intake together with average daily weight derived from weighings taken from each visit to the feed station. In non-computer controlled systems the feed record will hold the accumulated daily feed intake data since the previous intake information was recorded. The period over which feed intakes will be accumulated will normally be determined by the weigh period.

As a minimum each intake record should include:

1. Animal identification.
2. Date of record.
3. Quantity of feed eaten in this period.

Weight details of animals on test

This record will store the weight of the animal. Weighings should be taken on a routine basis while minimising gut-fill variation. Weighing the test animals on a regular basis facilitates the close monitoring of performance and early diagnosis of any difficulties within the test. Routine weighings together with a matching feed intake record facilitates the computation of within weigh period daily gains and feed efficiencies together with cumulative daily gains on test and feed conversion efficiency statistics. Depending on the design of the test it may be possible to combine the weight and feed intake details on a single record.

As a minimum the record should record:

1. Animal ID.
2. Date of weighing.
3. Weight.