title: Effects of dry period length and dietary energy source on milk yield, energy balance, and metabolic status of dairy cows over 2 consecutive years: Effects in the second year.
abstract: The objective of the current study was to evaluate the effect of dry period (DP) length on milk yield, energy balance (EB), and metabolic status in cows fed a lipogenic or glucogenic diet in the second year after implementation of DP and dietary treatments. Holstein-Friesian dairy cows (n=167) were assigned randomly to 1 of 3 DP lengths (0, 30, or 60d) and 1 of 2 early lactation diets (glucogenic or lipogenic) for 2 consecutive years. Results of the first year were reported previously. In the second year, 19 cows in the 0-d DP group were attributed to a new group (0→67d DP) because these cows had a milk yield of <4kg/d at least 30d before expected calving date and were dried off. Milk yield was recorded and EB was calculated from wk -8 to 9 relative to calving. Blood samples were taken weekly from wk -3 to 8 relative to calving. Liver samples were taken in wk -2, 2, and 4 relative to calving. At the onset of lactation, cows with a 0-d or 0→67-d DP had greater body condition score (BCS) than cows with a 60-d DP. During the first 9wk, cows with a 0- or 30-d DP produced 5.0 and 4.3kg less milk per day, respectively, but had similar EB compared with cows with a 60-d DP. Cows with a 0- or 30-d DP produced additional milk precalving, which could compensate milk yield losses in the first 9wk postcalving. Cows with a 0-d DP did not have milk yield losses or improve EB in the second year as much as in the first year. Cows with a 0-d DP had greater plasma insulin and insulin-like growth factor-I (IGF-I) and lower liver triacylglycerol concentrations than cows with other DP lengths. Cows with a 0→67-d DP had lower EB, and greater plasma free fatty acids (FFA) and β-hydroxybutyrate (BHB) concentrations than cows with other DP lengths. Feeding a glucogenic diet increased plasma glucose, IGF-I, and insulin concentrations, and decreased plasma FFA, BHB, and urea concentrations compared with a lipogenic diet, independent of DP length. In conclusion, omitting the DP or feeding a glucogenic diet improved metabolic status in early lactation of the second year after implementation of DP length and dietary treatments, although effects of omitting the DP were less pronounced in the second year than in the first year. The less pronounced improvement of EB in the second year was related to the high BCS at the onset of lactation and reduced milk yield losses in cows with a 0-d DP.
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.affiliation: Livestock Research, Wageningen University and Research Centre, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: G J
authors.initials: GJ
authors.lastname: Remmelink
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, CH-3012 Bern, Switzerland.
authors.forename: J J
authors.initials: JJ
authors.lastname: Gross
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, CH-3012 Bern, Switzerland.
authors.forename: R M
authors.initials: RM
authors.lastname: Bruckmaier
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands.
authors.forename: B
authors.initials: B
authors.lastname: Kemp
authors.affiliation: Adaptation Physiology Group, Department of Animal Sciences, Wageningen University, PO Box 338, 6700 AH Wageningen, the Netherlands. Electronic address: Ariette.vanKnegsel@wur.nl.
authors.forename: A T M
authors.initials: ATM
authors.lastname: van Knegsel
mesh_terms: D020155:3-Hydroxybutyric Acid / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000662:veterinary*; D004041:Dietary Fats / Q000032:analysis; D004734:Energy Metabolism; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D007328:Insulin / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007774:Lactation; D008892:Milk / Q000737:chemistry / Q000378:metabolism*; D008894:Milk Proteins / Q000032:analysis; D014280:Triglycerides / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D004041:Dietary Fats; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008894:Milk Proteins; D014280:Triglycerides; D007334:Insulin-Like Growth Factor I; D020155:3-Hydroxybutyric Acid
keywords: continuous milking; energy metabolism; long-term effect