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item Kuhn, Melvin
item Hutchison, Jana
item Norman, H

Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2004
Publication Date: 7/25/2004
Citation: Kuhn, M.T., Hutchison, J.L., Norman, H.D. 2004. Minimum dry period length to maximize performance [abstract]. Journal of Dairy Science. 87(Suppl. 1):56.

Interpretive Summary:

Technical Abstract: The objective of this research was to find the minimum dry period length while maintaining performance in the subsequent lactation. The number of days dry, month of calving in the subsequent lactation, linear and quadratic effects of the last somatic cell score in the previous lactation, linear and quadratic effects of previous days open, and linear and quadratic effects of age at subsequent lactation were included in the model to look at the effect of dry period length on actual milk yield in the subsequent lactation, adjusted for producing ability. Data included Holstein cows first calving from 1997 to 1999. There were 64,100 records with a second lactation, 28,376 with a third lactation, and 11,997 with a fourth lactation. Peak yield during the following lactation occurred at a dry period length of 45 to 60 days for parities 2, 3, and 4. A difference in milk production of +33, +50, and -16 kg between 56 to 60 and 61 to 70 days dry was not significant for lactations 2, 3, and 4, respectively. A dry period length over 70 days resulted in a 250, 622, and 727 kg decrease in milk production for lactations 2, 3, and 4, respectively. Although peak yield in subsequent lactation occurred between 45 and 60 days, the rate of increase from zero to 45 days was not linear. Cows that were dry from zero to 35 days following first, second, and third lactations showed an average decrease of 1111, 491, and 1802 kg in second, third, and fourth lactations, respectively. In contrast, cows that were dry from 35 to 45 days had an average loss of only 280, 172, and 182 kg in lactations two, three, and four, respectively. Further research will determine optimum dry period length for lifetime yield, somatic cell score, female fertility, fat and protein percentages, and productive life.