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Commencement of luteal activity in three different selection lines for milk yield and fertility in Norwegian Red cows

Garmo, Randi T.; Ropstad, E.; Havrevoll, Ø.; Thuen, E.; Steinshamn, H.; Waldmann, W. and Reksen, O. (2009) Commencement of luteal activity in three different selection lines for milk yield and fertility in Norwegian Red cows. Journal of Dairy Science, 92, pp. 2159-2165.

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Summary

Relationships among commencement of luteal activity (C-LA), milk yield, and energy balance (EB) were investigated in 3 selection lines of Norwegian Red cows at the Norwegian University of Life Sciences from 1994 through 2001. The cows were selected for low genetic merit for milk yield (LMP), high genetic merit for milk yield (HMP), and a combination of high indices for milk yield and fertility (HI). Breeding values for fertility were based on 56-d nonreturn rate. The material included 268 lactations from 147 cows. Milk samples for progesterone analysis were drawn 3 times weekly from 1994 through 1998, and 2 times weekly from 1999 to 2001. Commencement of luteal activity was defined as the first 2 consecutive measurements of progesterone concentration >3 ng/mL not earlier than 10 d after calving. Selection line was significantly related to C-LA, so that the least squares mean days from calving to C-LA were 22.5, 30.4, and 27.2 d for LMP, HMP, and HI cows, respectively. The HMP cows produced more milk than the LMP cows. The average milk yield in the sixth week of lactation was 24.0, 27.1, and 25.3 kg for LMP, HMP, and HI cows, respectively. The interval to C-LA decreased for the HMP and HI cows after phenotypic adjustment for EB in the model. Least squares means for the interval to C-LA were 23.2, 29.7, and 25.6 d for the LMP, HMP, and HI cows, respectively, in a model that included parity, selection lines, and EB as covariates. Cumulated EB during the first 4 wk of lactation, which itself differed between selection lines, did not fully account for differences in interval to C-LA between selection lines. Thus, the results of the present investigation indicate that selection for milk yield negatively affects C-LA over and above the effects caused by concurrent changes in EB. The increase in days to C-LA caused by selection for high yields can be reduced if selection for milk yield is combined with fertility in the breeding program


EPrint Type:Journal paper
Keywords:luteal activity, genetic merit, fertility, dairy cow
Subjects: Animal husbandry > Production systems > Dairy cattle
Animal husbandry
Animal husbandry > Breeding and genetics
Animal husbandry > Feeding and growth
Research affiliation: Norway > UMB - Norwegian University of Life Sciences
Norway > Bioforsk - Norwegian Institute for Agriculture and Environmental Research > Bioforsk Organic Food and Farming Division
Norway > NVH - Norwegian School of Veterinary Science
Norway > Other organizations
Deposited By: Steinshamn, Dr Håvard
ID Code:16852
Deposited On:18 Mar 2010 12:39
Last Modified:06 Jun 2011 09:02
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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