Section 02 – Cattle Milk Recording

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Introduction

Information about milk production traits is very important for managing and breeding dairy herds. The milk recording process starts with the collection of animal identification, a calving date of milking cows, the amount of milk given and the date with time or time frame of a day. A milk sample may be taken. The obtained milk sample is analysed for milk constituents. The results of the analysis plus the data about milk yield and time of milking are stored in a database. Subsequently a number of parameters, cumulative yields and indices are calculated and stored in the database and, finally, reported to the farmer

This section (2) of the ICAR Guidelines focuses on the milk recording process for dairy cattle.

Definition and terminology

A list of important definitions for terms and abbreviations used in these guidelines is provided by Cattle Milk Recording#Definition and terminology

Table 1. Definitions of Terms used in these guidelines.
Term Definition
24-hour yield The amounts of milk, fat and protein produced by the individual cow over 24 hours.
Accumulated yield The amounts of milk, fat and protein produced by the individual cow during an appointed period of time, e.g. a calendar year.
AMS Automatic Milking System
Average yield The amounts of milk, fat and protein produced by all cows in the herd in average during the appointed time period.
Expected milk secretion rate Average milk secretion rate of a cow calculated as grams per minute of a given period of time.
Expected milking interval Average milking interval of a given time period.
Individual milking A single act of collecting milk from one cow.
Individual milking yield The amount of milk produced by a cow in an individual milking.
Interrupted milking A milking is considered interrupted if the milk secretion rate is less than 80% of the expected.
Lactation The period from an individual cow’s calving to her dry off or culling (lactation can be incomplete)
Lactation yield The amount of milk, fat and protein produced by an individual cow during the lactation.
Milk analysis results The set of milk constituents (e.g. fat, protein, lactose, urea, somatic cell count) in a milk sample analysed by a laboratory.
Milk recording The whole process of milk data collection described in paragraph 1 of this guideline. This is also known as Dairy Herd Improvement (DHI).
Milk secretion rate Milk secretion rate of a cow calculated as grams per minute for the milking interval.
Milking interval The period between two consecutive milkings.
Recorded cow Any cow in a recorded herd.
Recorded herd Any herd that is enrolled in milk recording.
Recording The action of measuring a cow’s milk yield by collecting the data and processing it (e. g. by use of a database). This is also known as testing or test day.
Recording interval The period between two consecutive recordings.
Recording period The period between the end and beginning of the recording on a single recording.
Sample position Position of the sample in the sampling unit.
Sampling The action of taking a representative sample of a cow’s milk. Sampling is generally attached to a recording.
Sampling unit A device for the collection of milk samples.
Standard lactation The period from an individual cow’s calving until her dry off or 305th day since her calving.
Unrecorded milking A milking is considered unrecorded if the milking interval is longer than expected and milk secretion rate is less than 80% of the expected.
Vial The vessel containing a milk sample, also known as bottle etc.

Scope

Figure 1 gives a pictorial summary of the main elements of this guideline.

In summary, this section of the ICAR Guidelines covers the milk recording process from the enrolment of a herd for milk recording, through to the delivery of information which a herd owner can use to assist in a range of decisions.

Figure 1. Scope of Section 2 -Dairy cattle milk recording.

Not covered in this section are:

  1. Standards and guidelines for ICAR approval of milk recording devices. Please consult Section 11 for this subject.
  2. Standards and guidelines for ICAR approval of ID devices. Please consult Section 10 for this subject.
  3. Standards and guidelines for preparation of milk samples and for quality assurance of milk analysis. Please consult Section 12 for this subject.
  4. Standards and guidelines for in-line milk analysis on the farm. Please consult Section 13 for this subject.

Sub-sections

Recording

Standards and Guidelines for milk recording

These standards and guidelines for milk recording are valid for all milking systems, including AMS where applicable.

General Standards and Guidelines for milk recording

  1. ICAR-approved (electronic) milk meters and sampling devices must be used on the recording day (see Procedure 1 of Section 11 - Guidelines for Testing, Approval and Checking of Milk Recording Devices). The list of approved milk meters, jars and AMS and automatic milk sampler/tray combinations sampling devices can be found on the ICAR web page.
  2. Milk weights are recorded for each milking of the recording period. The measurement may be done using any of the ICAR approved recording devices, or by weighing. The minimum accuracy of the measurement is 0.2 kg.
  3. Where milk constituents are analysed, the equipment used must meet ICAR standards for accuracy. Please consult Sections 12 and 13 of the Guidelines for details.
  4. The accuracy of the equipment used for milk recording and sampling must be checked by an agency approved by the member organisations, on a regular and systematic basis using methods approved by ICAR. The list of methods is given in Procedure 6 of Section 11 - Procedure for Evaluation of Installation and Routine Calibration Procedures for Recording and Sampling Devices.
  5. All analyses of the constituents of a milk sample must be carried out on the same milk sample.
  6. These samples should ideally represent the 24-hour milking period.
  7. If milk samples do not represent a 24-hour period, the results of milk analyses must be corrected to a 24-hour period by a method approved by ICAR (see 9.4 Standard methods for calculating 24 hour yields).
  8. In cases where the duration of recording deviates from 24 hours, the results must be converted into 24-hour yields. Only approved 24-hour yield calculation methods can be used. The appropriate methodology is described in (9.4 Standard methods for calculating 24 hour yields).
  9. As date of recording, we recommend to use the date on which the last sample was taken. As alternative, the date of the first sample can be used.
  10. Calculation methods
    1. The quantities of milk and milk constituents shall be calculated according to one of the methods outlined in this section of the ICAR Guidelines (see 9.4 Standard methods for calculating 24 hour yields).
    2. Member organisations should keep the ICAR Secretariat informed about the calculation methods being used by the records processing operations in their organisation or country and shall be responsible for ensuring that the records are corrected and calculated as specified in this section of the ICAR Guidelines.

Standards and Guidelines for milk recording using AMS

This subsection covers systems where milk weights, milk quality or other traits of the cows are monitored constantly and automatically. This can be done in both automatic and manually operated milking systems.

Requirements:

  1. Animal identification is automatic and reliable. Farm transponders can also be used for automatic identification if they are linked to the cow’s official identification in farm software.
  2. All individual milkings must be recorded from all AMSs in the farm and transmitted to the recording database for calculation, interrupted milkings included.
  3. For official milk recording purposes, the data file obtained from electronic milk meters must contain the following: 1) Cow ID, 2) Milking time stamp, 3) Milk weight and 4) Sampling stamp to mark the milking where the sample comes from.
  4. All milkings within the recording period may be sampled, and in this case the samples should be analysed separately. Alternatively, a one-milking sample can be taken for each cow, followed by fat correction calculation.
  5. All cows in milk on the recording day have to be sampled. The sampling device must remain in operation until all cows are sampled. When the number of available sampling devices is smaller than the number of AMS units, sampling may need to be prolonged beyond one day to allow complete sampling of all cows. In that case, the sampling device has to be moved between AMS units.
  6. During sampling, the automatic sampler must be monitored to make sure there are vials left for the next cows.
  7. 24-hour yield calculations must be carried out by a MRO, independently of the AMS manufacturer. This is done in order to guarantee harmonisation of calculation methods between the different brands of equipment and software.
  8. Data of all milkings over a given time period must be collected for the 24-hour milk yield calculation. A 96-hour data collection period is recommended.

Recommendations:

  1. Ideally, data of all milkings should be collected and used to compute lactation yield.
  2. Description of formats to exchange data recorded by an AMS can be requested from the manufacturer or the ICAR ADE data exchange standard for milking data can be used.
  3. In the case of milk recording method B (see 5.4.1) with AMS, the milk recording organization should make sure that the farmer knows how to load or transfer data.
  4. Data can be extracted by: 1) manual operation by MRO Technician’s or Farmer (file extraction), 2) automated system and data transfer through an Application Programming Interface (API), 3) another data transfer and exchange system.
  5. Raw milk recording data from the AMS must be easily accessible for MRO data processing.
  6. For official milk recording purposes, the data file obtained from electronic milk meters may also contain the following: 1) Vial ID (this is obligatory with M sampling scheme), 2) Milking duration, 3) Milking speed, 4) Incomplete milking in automatic milking systems and 5) Other relevant data measured or reported by the equipment.
  7. Individual milkings should be tested for milk secretion rate in order to detect interrupted and unrecorded milkings, which in turn have an effect on the calculated 24-hour yields. If there is an interrupted milking or a milking that follows an interrupted milking at the beginning of the recording period, these two milkings must be excluded from the calculations. During the recording period they can be excluded but do not need to be.
  8. It is recommended to individually sample all milkings within the 24-hour recording period for 24-hour fat content calculation due to the high variability of milking frequency and milk fat content. In cases where sampling all milkings is not possible, please consult Chapter 2 of Procedure 1 of Section 2 for approved correction calculation methods.
  9. It is recommended to sample only milkings with a preceding interval longer than 4 hours.


Authorisation to record

It is recommended that professional milk recording technicians are trained and certified before they carry out recordings on their own. Ideally, such training includes a period of supervised work with a certified technician. Where such a certification system is in place, it is not allowed to record without an authorisation.

It is also recommended that frequent training is given to milk recording technicians on new technologies and equipment, safety instructions and data quality issues.

In B and C recording, farmers or their employees doing the practical recording need to be capable of operating the recording equipment correctly (e.g. milk meters, data capture tools) and are familiar with recording techniques.

It is recommended to have a conformation test from a certified recording agency and that frequent training take place.

Cows to be recorded

In a recorded herd, all milk-producing cows must be recorded on each recording day. Acceptable reasons for missing data are discussed below, in 5.5 Missing results and/or abnormal intervals on page 17.

However, if a cow is permanently excluded from milk production, she can also be excluded from milk recording. This may happen through retirement or through use as a suckling cow. In each case it must be certain that the cow will never again produce milk to the bulk tank on the same farm.


Identification (ID)

Herd ID

Each herd in milk recording must be allocated a unique permanent identification number.

Animal ID

An official milk recording system must be based on a clearly identifiable and unique animal ID. It is recommended that one identification scheme for the whole country is used. Animal identification must also be in accordance with national and international regulation (e.g. EU member countries with EU legislation - 1760/2000 for cattle), and with relevant parts of currently valid ICAR Guidelines. The animal must be marked with an ICAR approved identification device or system. If the ID of imported animals is changed, the connection to the original ID must be maintained. Management numbers for cows can be used aside the official ID.

Identification of the sample vial

The sample, the milk weight and the cow ID must be linked at the milking.

Vials can be identified according to:

  1. Vial placement in the sampling unit.
  2. Cow or sample ID written on the vials.
  3. Barcoded vial with printed cow ID.
  4. Barcoded vial with cow ID registered at the milking.
  5. RFID vial with cow ID registered at the milking.
Sample identification without electronic equipment

Samples are identified according to their placement in the sampling unit. Additionally, sample or cow numbers can be written on the vials with a waterproof marker. If this marking is not done, there must be a sure and efficient way to identify sample No. 1 (e.g. different colour) and the sequence of other samples.

Each sampling unit must be connected to a list of samples where cow ID is given for each sample. Each transportation box also has to carry the relevant herd ID’s and, preferably, the sampling dates.

Barcoded vials

Samples are identified according to the barcode on the vial label.

If the label contains cow and/or herd ID, no electronic equipment is needed at the recording. The samples can be sent to the laboratory without accompanying sample lists or herd ID markings on the box.

If the label contains a random sample ID number, the cow ID must be connected with it on the farm. This is done with a barcode reader and computer programmes making the connection possible.

Vials with RFID

Samples are identified according to the RFID chip in the vial. This system requires the use of RFID readers and specific computer programmes creating a file where the cow and vial ID’s are connected.

Automatic sampling systems

In automatic milking systems (AMS), ICAR approved automatic samplers have to be used. Sample identification in these systems can be based on vial placement, barcode or RFID. The file with corresponding cow ID is in the management programme of the milking system. Data transfer is carried out with specific software and via a specific interface from the AMS to the MRO.

Sample ID in the laboratory

For impartiality and better quality, it is recommended that the samples are identified without cow ID and sent to the laboratory anonymously and the analysis results are merged afterwards in the data processing centre.

Connection of the sample to milking and 24 h yield

Sample and milk weight from the same milking

The ideal situation is that the sample and milk weight represent the same milking.

Sample from one milking, milk weight from two

A corrected analysis is routinely attached to the 24-hour yield.

Sample from one milking, milk weight from two or more, corrected by intervals

In this case, a 24-hour-yield is also combined with a one-milking sample, but the 24‑hour yield is obtained by correcting the recorded milkings according to the length of the preceding milking intervals. For example, if a cow has produced 20 kg milk in two milkings and the preceding intervals total 20 hours, her 24-hour yield is calculated as 20 kg * (24 h/20 h) = 24 kg. A corrected analysis is attached to this 24‑hour yield.

Sample from one milking or day, milk weight from several days

With electronic milk meters, it is possible to use the milk production from several days. This gives better accuracy of milk yield estimation; the highest accuracy with uncorrected milk weights is reached using a 4-day average. The problem is that the sample results become disconnected from the milk yield and a loss in fat and protein yield accuracy will occur. Ideally, fat and protein production should be connected to the recording day even in AMS.

In this case, there are three options to connect samples to the 24-hour yield:

  1. Milk weight is estimated from a longer measurement period but for fat and protein yield estimation only the milk yield on sampling day is used.
  2. Information only from the recording day for constituents in milk and milk yield estimation.
  3. Combination of multiple day milk yield with constituents from sampling. See ICAR procedures for using data from more than one day (Lazenby et al., 2002), estimation of fat and protein yield (Galesloot and Peeters , 2000).

The analysis data are merged with milk weights in the laboratory or data processing centre and the date of the analysis must be known.


Traits to be recorded

In official milk recording, the following data have to be recorded, wherever available:

  1. Identification of each cow in the herd, even if they remain in the herd for a very short time.
  2. Birth date, sex, breed and parents of each animal when known.
  3. All services and embryo flushings and transfers: date, recipient, sire, dam of the embryo.
  4. All animal deaths and movements between farms and owners.
  5. Recording dates and locations.
  6. Milk yields for each cow and recording date.
  7. Fat content in milk for each cow and sampling date.

It is recommended to record also the following:

  1. Protein content in milk for each cow and sampling date.
  2. Milk somatic cell count for each cow and sampling date.
  3. Other results obtained from milk analysis.
  4. Milking duration and milking speed where possible.
  5. Milking times during recording.
  6. Recording methods and respective symbols used in records.
  7. Information about cow during the rearing period.

Recording Method

The recording method for the herd consists of using five different symbols for:

  1. Responsibility for the practical recording.
  2. Sampling scheme.
  3. Recording interval.
  4. Sampling interval (if different from the above).
  5. Number of milkings per day (especially any deviation from 2x milking).
Table 2. Symbols for milk recording schemes.
Responsibility for recording Sampling scheme Recording frequency Sampling frequency Number of milkings per day
A P 1 1 1 x
B E 2 2 2 x
C Z 3 3 3 x
T 4 4 4 x
M 5 5 R x
etc. etc. etc. 1.4x
S x

As an example: Recording method is CP36, 2x means that this is a recording where records/ samples are taken partly by the owner (farmer), and partly by a technician from the MRO, where the recording frequency is every 3 weeks, where the sampling frequency is every 6 weeks, and where the number of milkings per day is 2. If a national nomenclature system is used, it should be possible to transfer this system into ICAR nomenclature.

The reference milk recording method is by a representative of the recording organisation, measuring and sampling every four weeks, with proportional sampling and two milkings per day (AP44, 2x).

Recording other than by the reference method must be indicated using the appropriate symbols.

It is recommended that a limit is set for changing the recording method e.g. so that normally it is only possible to change the method twice per year.

It is recommended to store the Recording method ICAR code on event level, which is for every single cow milking stored in the database. The recording method for an accumulated yield is derived from the recording method of the underlying single milkings, in which case the recording method with the highest frequency is used to calculate the accumulated yield.

In the next sections the symbols are explained:

Responsibility for the recording

This symbol indicates who is responsible for measuring the milk yields and taking samples in the herd.

  1. Representative of the MRO (Method A; see Section 1.3)
  2. Farmer or his/her representative (Method B; see Section 1.3)
  3. Mixed responsibility (Method C; see Section 1.3)

ICAR Standards for sampling schemes

Proportional sampling (P)

Samples and milk weights are taken at each milking during the recording day. The sampled amount corresponds to the milk yield of each milking. This is achieved by the use of a pipette in equal number of pipetting at each milking or of a specially designed tool which ensures proportional sampling to create one mixed sample. This is the default sampling scheme with no necessary correction to the analysis results, all other schemes must be reported.

Equal measure sampling (E)

Samples and milk weights are taken at each milking during the recording day. The amount of the sample is measured to be equal at each milking and mixed into one sample. The analysis results for fat should be corrected if one of the milking intervals is shorter than 10 or longer than 14 hours.

Multiple sampling (M)

Samples are taken at more than one milking during the recording day while milk weights are taken at each milking or over several days. Samples from different milkings are not mixed but they are kept in distinct vials so that each cow has at least two samples. The analysis results must be corrected to correspond to the 24-hour fat and protein yields. For example: a cow is milked 3x during 24 hours and 2 or 3 separate samples are taken, kept and analysed in different vials. This is the gold standard for AMS. It produces the most accurate results but is more expensive.

One-milking sampling with milk weights from more than one milking (Z)

Samples are taken from one milking during the recording day while milk weights are taken at each milking or over several days. The analysis results must be corrected using one of the methods described in Procedure 1 of Section 2.

Alternated one-milking recording (T)

Samples and milk weights are taken during one milking, alternating between morning and evening milkings. The milk weights and analysis results must be corrected using one of the methods described in Procedure 1 of Section 2.

Constant one-milking recording (C)

Samples and milk weights are taken during one milking, constantly during morning or evening milking. The milk weights and analysis results must be corrected using one of the methods described in Procedure 1 of Section 2.

In-line analysis recording (I)

Milk is not sampled but its constituents are continuously analysed by a stationary analyser.

ICAR Standards for recording and sampling intervals

Table 3. Standards for recording and sampling intervals.

Recording or sampling interval (weeks) Minimum number of recordings or samplings per year Interval between recordings or samplings (days)
Min Max
1 44 4 10
2 22 10 18
3 15 16 26
Reference method 4 11 22 37
5 9 32 46
6 8 38 53
7 7 44 60
8 6 50 70
9 5 55 75
Daily 310 1 3

ICAR standards for number of milkings per day

Table 4. Symbols for number of milkings per day.

Number of milkings per day Symbol
Once per day milking 1 x
Two milkings 2 x
Three milkings 3 x
Four milkings 4 x
Continuous milking (e.g. AMS) R x
Regular milkings not at the same times on each day (e.g. 10 milkings per week) 1.4x
Shown as the average number of milkings per day.
Animals that are both milked and suckled. (Number of times milked to prefix the S) S x


Where a herd is dry for a period of the year, the minimum number of recordings should be adjusted proportionately to the production period.

Minimum number of herd recordings should be at least 85% of the normal number of recordings.

Missing results and/or abnormal intervals

A recorded 24-hour yield is the best estimate of the yield and the constituents of the milk, weighed, sampled and recorded within 24 hours on the day of recording.

  1. When herds are normally milked at intervals such that the recording day is other than 24 hours, the yields shall be adjusted to a 24-hour interval using the following procedure (or other procedures approved by the ICAR):
    1. Divide 24 by the interval, then multiply by the yield. For example:
      • For a 25 hour interval  (24/25) x 35 kg = 33.6 kg
      • For a 20 hour interval (24/20)  x 35 kg = 42.0 kg
  2. A recording is a set of daily test values for a given animal on a given day of recording, one or some or all of them can be missed (missing values)
  3. Missing values can be due to:
    1. Out of range.
    2. Sickness.
    3. Disaster.
    4. No sample analysis results.
    5. The number of the official and complete (milk, fat and protein) recordings in the lactation or other accumulated yield should be reported.

e.      Permitted range of the daily recorded values is given in Table 5. Outside of these ranges, the daily recor[1]ded value will be considered as a missing value.

Table 5. Permitted range of the daily recorded values.

Milk (kg) Fat % Protein %
Min Max Min Max Min Max
Main Dairy Cattle Breeds 3.0 99.9 1.5 9.0 1.0 7.0
High Fat1 Cattle Breeds 3.0 99.9 2.0 12.0 1.0 9.0


f.       The true daily recorded values collected from animals labelled by the farmer as sick, injured or under treatment must be used in the computation of the lactation record unless the milk yield is less than 50% of the previous milk yield or less than 60% of the predicted yield. In such a case, the whole set of daily recorded values may be considered as missing.

g.      Estimates of the missing values of a daily recording can be computed by using interpolation procedures or by more sophisticated procedures approved by ICAR.

[1] Note: High fat breeds have breed average higher than 5.0 for fat %.

bull code


age at first calving

age at first calving

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