title: The influence of body condition on the fasting energy metabolism of nonpregnant, nonlactating dairy cows.
abstract: The objective of this experiment was to investigate the effect of cow body condition score on fasting heat production. Twelve nonpregnant, nonlactating Holstein-Friesian cows were selected from within the dairy herd at the Agricultural Research Institute of Northern Ireland. Six of these animals (group A) had condition scores > or = 4.5, and the remainder (group B) had condition scores <2. All cows were offered dried grass pellets at estimated maintenance energy level (0.58 MJ of metabolizable energy/kg(0.75)) for a minimum of 21 d. The diet also supplied 2.5 times the metabolizable protein requirement for maintenance. Following this, each cow underwent a 5-d fast in open circuit respiration calorimeters during which fasting heat production (FHP) was measured. On completion of measurement, group A was fed to reduce condition score (CS) below 2, while group B was fed to raise each individual condition score above 4.5. When the appropriate condition scores were achieved, dried grass pellets were again offered at maintenance for a minimum of 21 d, and fasting heat production was measured. It was observed that fasting heat production (MJ/kg(0.75)) was significantly higher for cows with low body condition (<2; ultrasonic fat depth < or = 2.9 mm) compared with cows displaying high body condition (> or = 4.5; ultrasonic fat depth > or = 8.2 mm). A linear relationship between condition score and fasting heat production (MJ/kg(0.75)) was defined by regression analysis as; FHP (MJ/kg(0.75)) = 0.501(SE 0.0121) - 0.030CS (SE 0.0035).
authors.affiliation: Agricultural Research Institute of Northern Ireland, Hillsborough, County Down.
authors.forename: J W
authors.initials: JW
authors.lastname: Birnie
authors.forename: R E
authors.initials: RE
authors.lastname: Agnew
authors.forename: F J
authors.initials: FJ
authors.lastname: Gordon
mesh_terms: D000821:Animal Feed / Q000032:analysis* / Q000592:standards; D000818:Animals; D001823:Body Composition / Q000502:physiology*; D002153:Calorimetry, Indirect / Q000662:veterinary; D002417:Cattle / Q000378:metabolism*; D004032:Diet / Q000592:standards / Q000662:veterinary*; D004734:Energy Metabolism; D005260:Female; D007494:Ireland; D006109:Poaceae / Q000737:chemistry; D012044:Regression Analysis; D022722:Thermogenesis