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Lactation Calculation Methods Working Group

Members

The following are the members of the Lactation calculation methods Working Group:

Purpose

The overall objective of the Group is to identify improved lactation yield estimation procedures. However, given the increasing flexibility of milk recording agencies worldwide, the focus of the group is to first compute an accurate 24 hr yield, then to combine the daily yields, measured in different ways, to estimate the lactation yield.

Progress Report

The Working Group has been working on two tasks: a) review and update of current ICAR Guidelines for milk recording; and b) development of guidelines for milk recording from Automated Milking Systems (AMS). Newly investigated methods for lactation calculation have been added to the current guidelines (ISLC, Best Prediction and MTP). Also, methods for AM/PM recording have been updated.

Regarding robotic milking system four group members have been involved in research on this topic (France, Germany, The Netherlands and Canada). Results from the French project showed an important effect of daytime, time interval since last milking and lactation stage on milk production and composition. Reducing time test to 12 hours instead of 24 hours seemed possible. Estimation of fat and protein yields and contents was precise enough for genetic and management applications. The German study concluded it was not possible to estimate daily fat content with a satisfying accuracy. The Dutch investigation has concluded that under specific restrictions (milking interval at least 4 hours, no interrupted milking and correct matching of sample jars with milkings) one sampled milking suffices to get a satisfactory estimate for the test day fat yield. In Canada, analysis of the data suggested that the optimal estimate of the milking rate is obtained using the 12 most recent milk weights or the last 4 days, regardless of days in milk or parity of the milked cow. Also, the length of the sampling period for fat and protein could be 14 to 16 hours with loss in accuracy in the range of 0.10 to 0.14 kilogram deviation in absolute 24-hour yield.

This year Working Group meeting occurred during the Interbull-ICAR meetings in Interlaken, Switzerland (May, 2002). Vigan Darvishi (new member in place of Marie Mathevon), Sander de Roos and Filippo Miglior attended the meeting. Zenting Liu was excused and, in his place, Fritz Reinhardt and Annette Buenger from VIT attended. Also, Don Lazenby (Ontario DHI), Petra Galesloot (NRS) and Betka Logar (Agricultural Institute of Slovenia) were invited to attend by the Chair..

The discussion focused on drafting guidelines for milk recording from Automatic Milking Systems (AMS) using results from recent research in the area carried out by group members. The Guidelines were distributed to the ICAR General Assembly and approved. However, research is still in progress in this area and Guidelines will be updated as soon as relevant results are found.

The major problem with AMS recording is the connection between estimation of milk yield and fat yield. Taking an average of the last 12 milkings or 4 days provides the optimal estimate of 24-hour milk yield. However, this estimate is quite disconnected with fat and protein yield that have been sampled on a given day. Thus, in the guidelines we tried to separate the two estimation procedures: a) estimation of 24-hour milk yield, and b) estimation of 24-hour fat and protein yield. For part a) conclusions from the Canadian research have been used, and for part b) results from the Dutch research have been used.

In the Guidelines a paragraph that deals with time of sampling was also added. However, given the conflicting results from research in France and Canada, on one side, and Germany, on the other side, it was we decided to include the following: ‘ … A less than 24-hour sampling period could be sufficient for a reasonable estimation of fat and protein percentages. However, further research is needed to confirm the minimum sampling period … '

Future Activity and Next Meetings

• Guidelines for AM/PM recording to be completed with estimation of lactation from alternate recording (up to now, we have only added the estimation of 24 hour yield)

• AMS guidelines:

  • New research to be performed to use the optimal estimate of 24-hour yield accounting for the negative relationship between fat percent and milk yield.

  • Estimation of 24-hour SCC

  • Terms for validating data from AMS

• Inclusion of literature references on current guidelines

Also, at the ICAR General Assembly it was suggested to consolidate AMS data from all interested countries to provide research results that are more robust for general application. The Chairperson will try to coordinate this task, and check for its feasibility.

The Working Group will meet at the ADSA meeting in Quebec (July 2002) and at the Interbull-EAAP meeting in Rome (August 2003).

Relevant Guidelines

Approved Guidelines

Proposed Guidelines (containing emendations, additional information, up-datings) are routinously debated among the Members of  the Working Group

Relevant Publications

Bouloc, N., J. Delacroix & V. Dervishi. 2002. Milk recording and automatic milking systems: features and simplification possibilities of recording procedures. Presented at the 33th biennial Session of ICAR, Interlaken, Switzerland, May 26-31, 2002.

Buenger A., T. Pasman, E. Bohlsen & F. Reinhardt. 2002. Transformation of AMS records to 24 hour equivalents. Presented at the 33th biennial Session of ICAR, Interlaken, Switzerland, May 26-31, 2002.

Galesloot, P.J.B. & R. Peeters, 2000. Estimation of 24-hours yields for milk, fat and protein based on data collected with an Automatic Milking System. 32th ICAR Session, Bled, Slovenia 14.-19. May 2000, EAAP publication No. 98: 147-153.

Lazenby, D., E. Bohlsen, K. J. Hand, D. F. Kelton, F. Miglior & K. D. Lissemore. 2002. Methods to estimate 24-hour yields for milk, fat and protein in robotic milking herds. Presented at the 33th biennial Session of ICAR, Interlaken, Switzerland, May 26-31, 2002.

Liu, Z., R. Reents, F. Reinhardt & K. Kuwan. 2000. Approaches to Estimating Daily Yield from Single Milk Testing Schemes and Use of a.m.-p.m. Records in Test-Day Model Genetic Evaluation in Dairy Cattle. J. Dairy Sci. 83:2672-2682.

Mao, I. L. 1995. Comparison of methods for calculating lactation total yield from test-day records. Report to Lactation Working Group of ICAR. (mimeo).

Miglior F., P. Galesloot, Z. Liu, M. Mathevon, A. Rosati, L.R. Schaeffer & P. VanRaden. 2000. Report of the ICAR Working Group on Lactation Calculation Methods: A Daily Yield Lactation Survey in Dairy Cattle. 32th ICAR Session, Bled, Slovenia 14.-19. May 2000,, EAAP publication no. 98: 273-274.

Miglior F., S. de Roos, Z. Liu, M. Mathevon, A. Rosati, L.R. Schaeffer & P. VanRaden, 2002. Report of the ICAR Working Group on Lactation Calculation Methods: Review and Update of Guidelines for Milk Recording. Presented at the 33th biennial Session of ICAR, Interlaken, Switzerland, May 26-31, 2002.

Norman, H.D., VanRaden, P.M., Wright, J.M., and Clay, J.S. 1999. Comparison of test interval and best prediction methods for estimation of lactation yield from monthly, a.m.-p.m., and trimonthly testing. J. Dairy Sci. 82(2):438-444. 1999.

Norman, H.D., J.R. Wright & J.S. Clay. 1998. Comparison of the test interval method with best prediction for estimating lactation yield. Proc. 6th World Congr. Genet. Appl. Livest. Prod. 23:343-346. Armidale, Australia, Jan. 11-16.

Peeters, R. & P. J. B. Galesloot. 2002. Estimating Daily Fat Yield from a Single Milking on Test Day for Herds with a Robotic Milking System. J. Dairy Sci. 85:682-688

Schaeffer, L.R. & J. Jamrozik, 1996. Multiple-trait prediction of lactation yields for dairy cows. J. Dairy Sci. 79:2044-2055.

Schaeffer, L.R., J. Jamrozik, R. Van Dorp, D.F. Kelton and D.W. Lazenby. 2000. Estimating daily yields of cows from different milking schemes. Livest. Prod. Sci. 65:219-227.

VanRaden, P.M. 1997. Lactation yields and accuracies computed from test day yields and (co)variances by best prediction. J. Dairy Sci. 80:3015-3022.

VanRaden, P.M. 1998. Best prediction of lactation yield and persistency. Proc. 6th World Congr. Genet. Appl. to Livest. Prod. 23:347-350. Armidale, Australia, Jan. 11-16, 1998.

Wilmink, J.B.M. 1987. Comparison of different methods of predicting 305-day milk yield using means calculated from within-herd lactation curves. Livest. Prod. Sci. 17:1.

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