title: The control of short-term feed intake by metabolic oxidation in late-pregnant and early lactating dairy cows exposed to high ambient temperatures.
abstract: The objective of the present study was to integrate the dynamics of feed intake and metabolic oxidation in late pregnant and early lactating Holstein cows under heat stress conditions. On day 21 before parturition and again on day 20 after parturition, seven Holstein cows were kept for 7days at thermoneutral (TN) conditions (15°C; temperature-humidity-index (THI)=60) followed by a 7day heat stress (HS) period at 28°C (THI=76). On the last day of each temperature condition, gas exchange, feed intake and water intake were recorded every 6min in a respiration chamber. Pre- and post-partum cows responded to HS by decreasing feed intake. The reduction in feed intake in pre-partum cows was achieved through decreased meal size, meal duration, eating rate and daily eating time with no change in meal frequency, while post-partum cows kept under HS conditions showed variable responses in feeding behavior. In both pre- and post-partum cows exposed to heat stress, daily and resting metabolic heat production decreased while the periprandial respiratory quotient (RQ) increased. The prolonged time between meal and the postprandial minimum in fat oxidation and the postprandial RQ maximum, respectively, revealed that HS as compared to TN early-lactating cows have slower postprandial fat oxidation, longer feed digestion, and thereby showing a shift from fat to glucose utilization.
authors.affiliation: Institute of Nutritional Physiology 'Oskar Kellner', Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany; Department of Animal Science, Campus of Agriculture and Natural Resources, P.O. Box 4111, University of Tehran, Karaj, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Eslamizad
authors.affiliation: Institute of Nutritional Physiology 'Oskar Kellner', Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: Ole
authors.initials: O
authors.lastname: Lamp
authors.affiliation: Institute of Nutritional Physiology 'Oskar Kellner', Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Derno
authors.affiliation: Institute of Nutritional Physiology 'Oskar Kellner', Leibniz Institute for Farm Animal Biology (FBN), Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany. Electronic address: b.kuhla@fbn-dummerstorf.de.
authors.forename: Björn
authors.initials: B
authors.lastname: Kuhla
mesh_terms: D000818:Animals; D002417:Cattle; D004435:Eating / Q000502:physiology*; D005247:Feeding Behavior / Q000523:psychology*; D005260:Female; D006358:Hot Temperature; D007774:Lactation / Q000502:physiology*; D017711:Nonlinear Dynamics; D010084:Oxidation-Reduction; D011247:Pregnancy; D012119:Respiration; D013312:Stress, Physiological / Q000502:physiology*; D013997:Time Factors
keywords: Dairy cow; Feed intake; Heat stress; Metabolic oxidation