title: The energy expenditure of 2 Holstein cow strains in an organic grazing system.
abstract: Until recently, measurements of energy expenditure (EE; herein defined as heat production) in respiration chambers did not account for the extra energy requirements of grazing dairy cows on pasture. As energy is first limiting in most pasture-based milk production systems, its efficient use is important. Therefore, the aim of the present study was to compare EE, which can be affected by differences in body weight (BW), body composition, grazing behavior, physical activity, and milk production level, in 2 Holstein cow strains. Twelve Swiss Holstein-Friesian (HCH; 616 kg of BW) and 12 New Zealand Holstein-Friesian (HNZ; 570 kg of BW) cows in the third stage of lactation were paired according to their stage of lactation and kept in a rotational, full-time grazing system without concentrate supplementation. After adaption, the daily milk yield, grass intake using the alkane double-indicator technique, nutrient digestibility, physical activity, and grazing behavior recorded by an automatic jaw movement recorder were investigated over 7d. Using the (13)C bicarbonate dilution technique in combination with an automatic blood sampling system, EE based on measured carbon dioxide production was determined in 1 cow pair per day between 0800 to 1400 h. The HCH were heavier and had a lower body condition score compared with HNZ, but the difference in BW was smaller compared with former studies. Milk production, grass intake, and nutrient digestibility did not differ between the 2 cow strains, but HCH grazed for a longer time during the 6-h measurement period and performed more grazing mastication compared with the HNZ. No difference was found between the 2 cow strains with regard to EE (291 ± 15.6 kJ) per kilogram of metabolic BW, mainly due to a high between-animal variation in EE. As efficiency and energy use are important in sustainable, pasture-based, organic milk production systems, the determining factors for EE, such as methodology, genetics, physical activity, grazing behavior, and pasture quality, should be investigated and quantified in more detail in future studies.
authors.affiliation: Agroscope, Institute for Livestock Sciences, Tioleyre 4, 1725 Posieux, Switzerland; Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstr. 109a, CH-3001 Bern, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Thanner
authors.affiliation: Agroscope, Institute for Livestock Sciences, Tioleyre 4, 1725 Posieux, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Dohme-Meier
authors.affiliation: Leibniz Institute for Farm Animal Biology, Institute of Nutritional Physiology "Oskar Kellner," Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Görs
authors.affiliation: Leibniz Institute for Farm Animal Biology, Institute of Nutritional Physiology "Oskar Kellner," Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: C C
authors.initials: CC
authors.lastname: Metges
authors.affiliation: Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstr. 109a, CH-3001 Bern, Switzerland.
authors.forename: R M
authors.initials: RM
authors.lastname: Bruckmaier
authors.affiliation: Agroscope, Institute for Livestock Sciences, Tioleyre 4, 1725 Posieux, Switzerland. Electronic address: fredy.schori@agroscope.admin.ch.
authors.forename: F
authors.initials: F
authors.lastname: Schori
mesh_terms: D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002245:Carbon Dioxide / Q000032:analysis; D002417:Cattle / Q000502:physiology*; D003612:Dairying; D004734:Energy Metabolism; D005260:Female; D007774:Lactation; D008892:Milk / Q000378:metabolism*; D009520:New Zealand; D058871:Organic Agriculture; D006109:Poaceae; D022722:Thermogenesis
chemical_list: D002245:Carbon Dioxide
keywords: Holstein-Friesian; dairy cow; energy expenditure; pasture