Comparing cows - including dry period and lactation length in a yield measure

Research output: Chapter in Book/Report/Conference proceedingAbstractAcademic

Abstract

To assess economic and environmental consequences of dry period length in dairy cows, milk yields have to be compared. Milk yield is mostly compared as yield in the 305 days after calving (305d yield), but this measure ignores extra milk yield in the previous lactation when cows are milked longer. In addition, it does not adjust for actual lactation length, while a shorter dry period may go together with a shorter calving interval. We aimed to 1) develop a just measure of milk yield that includes calving interval and dry period length and 2) apply this to compare 217 cows with a conventional, short or no dry period before 2nd calving. The data was a convenience sample from 14 commercial farms; herd and dry period length were confounded. An ‘effective lactation’ was set from 60 days before last calving to 60 days before the next calving and expressed in ‘effective yield’ in kg of fat-and-protein-corrected milk per cow per day. Thereby, it included possible extra milk in the previous lactation and excluded milk that depended on the next dry period choice. Cows without a dry period had a 22% lower 305d yield than cows with a conventional dry period. Adding the extra milk yield in the previous lactation and correcting for the shorter calving interval (355 vs. 408d), the effective yield was only 9% lower. The 305d yield of cows with a short dry period did not differ from cows with a conventional dry period, but the effective yield was 7% higher. When 1st lactation 305d yield was used as a covariate of genetic merit, the effective yield of cows with a short and conventional dry period did not differ, while it was 2 kg per day lower (across production levels) for cows without a dry period. The difference between results from 305d and effective yield emphasizes the importance of method choice when comparing cows. Effective yield enables a just comparison of milk yield when dry period length and calving interval vary.
Original languageDutch
Title of host publicationBook of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science
Place of PublicationWageningen
PublisherWageningen Academic Publishers
Pages140-140
Publication statusPublished - 2015
EventEAAP - 66th Annual Meeting 2015 - Warsaw, Poland
Duration: 31 Aug 20154 Sep 2015

Conference

ConferenceEAAP - 66th Annual Meeting 2015
CountryPoland
CityWarsaw
Period31/08/154/09/15

Cite this

Kok, A., van Middelaar, C. E., van Knegsel, A. T. M., Hogeveen, H., Kemp, B., & de Boer, I. J. M. (2015). Comparing cows - including dry period and lactation length in a yield measure. In Book of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science (pp. 140-140). Wageningen: Wageningen Academic Publishers.
Kok, A. ; van Middelaar, C.E. ; van Knegsel, A.T.M. ; Hogeveen, H. ; Kemp, B. ; de Boer, I.J.M. / Comparing cows - including dry period and lactation length in a yield measure. Book of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science. Wageningen : Wageningen Academic Publishers, 2015. pp. 140-140
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title = "Comparing cows - including dry period and lactation length in a yield measure",
abstract = "To assess economic and environmental consequences of dry period length in dairy cows, milk yields have to be compared. Milk yield is mostly compared as yield in the 305 days after calving (305d yield), but this measure ignores extra milk yield in the previous lactation when cows are milked longer. In addition, it does not adjust for actual lactation length, while a shorter dry period may go together with a shorter calving interval. We aimed to 1) develop a just measure of milk yield that includes calving interval and dry period length and 2) apply this to compare 217 cows with a conventional, short or no dry period before 2nd calving. The data was a convenience sample from 14 commercial farms; herd and dry period length were confounded. An ‘effective lactation’ was set from 60 days before last calving to 60 days before the next calving and expressed in ‘effective yield’ in kg of fat-and-protein-corrected milk per cow per day. Thereby, it included possible extra milk in the previous lactation and excluded milk that depended on the next dry period choice. Cows without a dry period had a 22{\%} lower 305d yield than cows with a conventional dry period. Adding the extra milk yield in the previous lactation and correcting for the shorter calving interval (355 vs. 408d), the effective yield was only 9{\%} lower. The 305d yield of cows with a short dry period did not differ from cows with a conventional dry period, but the effective yield was 7{\%} higher. When 1st lactation 305d yield was used as a covariate of genetic merit, the effective yield of cows with a short and conventional dry period did not differ, while it was 2 kg per day lower (across production levels) for cows without a dry period. The difference between results from 305d and effective yield emphasizes the importance of method choice when comparing cows. Effective yield enables a just comparison of milk yield when dry period length and calving interval vary.",
author = "A. Kok and {van Middelaar}, C.E. and {van Knegsel}, A.T.M. and H. Hogeveen and B. Kemp and {de Boer}, I.J.M.",
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pages = "140--140",
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Kok, A, van Middelaar, CE, van Knegsel, ATM, Hogeveen, H, Kemp, B & de Boer, IJM 2015, Comparing cows - including dry period and lactation length in a yield measure. in Book of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science. Wageningen Academic Publishers, Wageningen, pp. 140-140, EAAP - 66th Annual Meeting 2015, Warsaw, Poland, 31/08/15.

Comparing cows - including dry period and lactation length in a yield measure. / Kok, A.; van Middelaar, C.E.; van Knegsel, A.T.M.; Hogeveen, H.; Kemp, B.; de Boer, I.J.M.

Book of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science. Wageningen : Wageningen Academic Publishers, 2015. p. 140-140.

Research output: Chapter in Book/Report/Conference proceedingAbstractAcademic

TY - CHAP

T1 - Comparing cows - including dry period and lactation length in a yield measure

AU - Kok, A.

AU - van Middelaar, C.E.

AU - van Knegsel, A.T.M.

AU - Hogeveen, H.

AU - Kemp, B.

AU - de Boer, I.J.M.

PY - 2015

Y1 - 2015

N2 - To assess economic and environmental consequences of dry period length in dairy cows, milk yields have to be compared. Milk yield is mostly compared as yield in the 305 days after calving (305d yield), but this measure ignores extra milk yield in the previous lactation when cows are milked longer. In addition, it does not adjust for actual lactation length, while a shorter dry period may go together with a shorter calving interval. We aimed to 1) develop a just measure of milk yield that includes calving interval and dry period length and 2) apply this to compare 217 cows with a conventional, short or no dry period before 2nd calving. The data was a convenience sample from 14 commercial farms; herd and dry period length were confounded. An ‘effective lactation’ was set from 60 days before last calving to 60 days before the next calving and expressed in ‘effective yield’ in kg of fat-and-protein-corrected milk per cow per day. Thereby, it included possible extra milk in the previous lactation and excluded milk that depended on the next dry period choice. Cows without a dry period had a 22% lower 305d yield than cows with a conventional dry period. Adding the extra milk yield in the previous lactation and correcting for the shorter calving interval (355 vs. 408d), the effective yield was only 9% lower. The 305d yield of cows with a short dry period did not differ from cows with a conventional dry period, but the effective yield was 7% higher. When 1st lactation 305d yield was used as a covariate of genetic merit, the effective yield of cows with a short and conventional dry period did not differ, while it was 2 kg per day lower (across production levels) for cows without a dry period. The difference between results from 305d and effective yield emphasizes the importance of method choice when comparing cows. Effective yield enables a just comparison of milk yield when dry period length and calving interval vary.

AB - To assess economic and environmental consequences of dry period length in dairy cows, milk yields have to be compared. Milk yield is mostly compared as yield in the 305 days after calving (305d yield), but this measure ignores extra milk yield in the previous lactation when cows are milked longer. In addition, it does not adjust for actual lactation length, while a shorter dry period may go together with a shorter calving interval. We aimed to 1) develop a just measure of milk yield that includes calving interval and dry period length and 2) apply this to compare 217 cows with a conventional, short or no dry period before 2nd calving. The data was a convenience sample from 14 commercial farms; herd and dry period length were confounded. An ‘effective lactation’ was set from 60 days before last calving to 60 days before the next calving and expressed in ‘effective yield’ in kg of fat-and-protein-corrected milk per cow per day. Thereby, it included possible extra milk in the previous lactation and excluded milk that depended on the next dry period choice. Cows without a dry period had a 22% lower 305d yield than cows with a conventional dry period. Adding the extra milk yield in the previous lactation and correcting for the shorter calving interval (355 vs. 408d), the effective yield was only 9% lower. The 305d yield of cows with a short dry period did not differ from cows with a conventional dry period, but the effective yield was 7% higher. When 1st lactation 305d yield was used as a covariate of genetic merit, the effective yield of cows with a short and conventional dry period did not differ, while it was 2 kg per day lower (across production levels) for cows without a dry period. The difference between results from 305d and effective yield emphasizes the importance of method choice when comparing cows. Effective yield enables a just comparison of milk yield when dry period length and calving interval vary.

M3 - Abstract

SP - 140

EP - 140

BT - Book of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science

PB - Wageningen Academic Publishers

CY - Wageningen

ER -

Kok A, van Middelaar CE, van Knegsel ATM, Hogeveen H, Kemp B, de Boer IJM. Comparing cows - including dry period and lactation length in a yield measure. In Book of Abstracts of the 66th Annual Meeting of the European Federation of Animal Science. Wageningen: Wageningen Academic Publishers. 2015. p. 140-140