title: Effects of dry period length and dietary energy source on lactation curve characteristics over 2 subsequent lactations.
abstract: This study evaluated the effects of dry period (DP) length and dietary energy source on lactation curve characteristics over 2 subsequent lactations. It also evaluated the relationships of energy balance or metabolic status in early lactation with lactation curve characteristics in dairy cows. Holstein-Friesian dairy cows (n=167) were assigned randomly to 1 of 3 DP lengths (0-, 30-, or 60-d) and 1 of 2 early-lactation diets (glucogenic or lipogenic) for 2 subsequent lactations. In the second lactation following DP length treatments, 19 cows in the 0-d DP group were assigned to a 0→67-d DP group (actual days dry: 67±8d). Cows were allocated to this new group when they had a milk yield of <4kg/d at least 30d before their expected calving date. Fat- and protein-corrected milk (FPCM) was calculated weekly per cow in both lactations. Blood samples were taken weekly from calving to wk 4 after calving. A Wilmink lactation curve for each lactation was modeled based on FPCM yield records from calving through 305 DIM. During the first lactation following DP length treatments, cows with a 0- or 30-d DP had lower peak yield, later time of peak yield, and lower FPCM305than cows with a 60-d DP. In the second lactation following DP length treatments, cows with a 0- or 30-d DP had lower peak yield than cows with a 60-d DP. In both lactations, lactation persistency was not affected by DP length and none of the lactation curve characteristics were affected by diet. In parity >2 cows, total FPCM yield and average daily FPCM yield throughout 2 lactations did not differ among DP lengths. In addition, average energy balance in the first 4wk after calving had a negative relationship with peak yield and FPCM305, and a positive relationship with lactation persistency. Average plasma concentrations of free fatty acids and β-hydroxybutyrate had a positive relationship with peak yield and FPCM305, and a negative relationship with lactation persistency. Shortening or omitting the DP affected lactation curve characteristics in both lactations after implementation of DP length treatments but did not compromise FPCM yield compared with a conventional DP of 60d in parity >2 cows. Severe negative energy balance and poor metabolic status were related to greater peak yield, FPCM305, and lower lactation persistency.
authors: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors: J
authors: J
authors: Chen
authors: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands; Animal Production Systems Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors: A
authors: A
authors: Kok
authors: Livestock Research, Wageningen University and Research Center, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors: G J
authors: GJ
authors: Remmelink
authors: Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, CH-3012 Bern, Switzerland.
authors: J J
authors: JJ
authors: Gross
authors: Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, CH-3012 Bern, Switzerland.
authors: R M
authors: RM
authors: Bruckmaier
authors: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors: B
authors: B
authors: Kemp
authors: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands. Electronic address: Ariette.vanKnegsel@wur.nl.
authors: A T M
authors: ATM
authors: van Knegsel
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000378:metabolism; D000818:Animals; D002417:Cattle; D004032:Diet / Q000662:veterinary; D005260:Female; D007774:Lactation; D008892:Milk / Q000378:metabolism*; D010298:Parity
chemical_list: D020155:3-Hydroxybutyric Acid
keywords: dry period length; lactation persistency; long-term effect; milk yield