Influence of dietary fiber content and horn status on thermoregulatory responses of Brown Swiss dairy cows under thermoneutral and short-term heat stress conditions.

Autor: Reiche AM; Ruminant Nutrition and Emissions, Agroscope Posieux, 1725 Posieux, Switzerland. Electronic address: anna-maria.reiche@agroscope.admin.ch., Amelchanka SL; ETH Zurich, AgroVet-Strickhof, Eschikon 27, 8315 Lindau, Switzerland., Bapst B; Qualitas AG, 6300 Zug, Switzerland., Terranova M; ETH Zurich, AgroVet-Strickhof, Eschikon 27, 8315 Lindau, Switzerland., Kreuzer M; ETH Zurich, Institute of Agricultural Sciences, Eschikon 27, 8315 Lindau, Switzerland., Kuhla B; Research Institute for Farm Animal Biology (FBN), Institute of Nutritional Physiology, Wilhelm-Stahl-Allee 2, 18196 Dummerstorf, Germany., Dohme-Meier F; Ruminant Nutrition and Emissions, Agroscope Posieux, 1725 Posieux, Switzerland.
Jazyk: angličtina
Zdroj: Journal of dairy science [J Dairy Sci] 2023 Nov; Vol. 106 (11), pp. 8033-8046. Date of Electronic Publication: 2023 Aug 23.
DOI: 10.3168/jds.2022-23071
Abstrakt: In the present experiment, 10 horned and 10 disbudded mid-lactating Brown Swiss cows were included in a crossover feeding trial with a hay or hay and concentrate diet. The effects of dietary neutral detergent fiber (NDF) content and horn status on thermoregulatory responses under thermoneutral and short-term heat stress conditions were studied, as both are considered to ease the cow's thermoregulation under an environmental heat load. Cows received either ad libitum hay and alfalfa pellets (85:15, C-, NDF content: 41.0%) or restricted amounts of hay and concentrate (70:30, C+, NDF content: 34.5%). The level of restriction applied with the C+ diet was determined from pre-experimental ad libitum intakes, ensuring that both diets provided the same intake of net energy for lactation (NE L ). For data collection, cows were housed in respiration chambers for 5 d. The climatic conditions were 10°C and 60% relative humidity (RH), considered thermoneutral (TN) conditions (temperature-humidity index (THI): 52) for d 1 and 2, and 25°C and 70% RH, considered heat stress (HS) conditions (THI: 74), for d 4 and 5. On d 3, the temperature and RH were increased gradually. Compared with TN, HS conditions increased the water intake, skin temperature, respiration and heart rates, and endogenous heat production. They did not affect body temperature, feed intake, or milk production. Lowering dietary fiber content via concentrate supplementation lowered methane and increased carbon dioxide production. It did not mitigate physiological responses to HS. Although the responses of horned and disbudded cows were generally similar, the slower respiration rates of horned cows under HS conditions indicate a possible, albeit minor, role of the horn in thermoregulation. In conclusion, future investigations on nutritional strategies must be conducted to mitigate mild heat stress.
(© 2023, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
Databáze: MEDLINE
Externí odkaz: