Hair cortisol levels of lactating dairy cows in cold‐ and warm‐temperate regions in Japan

Abstract

We compared the hair cortisol levels of lactating dairy cows in a cold- and a warm-temperate region out of four climatic zones in Japan. We simultaneously investigated the effects of calving number, lactation period and month of hair sampling. Hair of nine Holstein lactating cows chosen from each region (i.e. 18 cows per sampling) was sampled in March, June, September and December. Number of calvings (1, 2, ≥3) and lactation duration (early: <100, middle: 101-200, and late: >201 days) were balanced between regions. Cortisol was extracted from hair by methanol, and its level was determined with a cortisol immunoassay kit. A multi-way analysis of variance revealed that the effects of month of hair sampling (P < 0.001) and its combination with region (P < 0.05) were significant. In a multiple comparison test, significant differences (P < 0.01) in hair cortisol level (pg/mg of hair) were found between June (13.0 ± 1.0) and the other 3 months, and between September (1.6 ± 0.2) and December (4.5 ± 0.3). The rise in cortisol level from March to June was more intense in the cold-temperate region. These results demonstrate the necessity of considering seasonal variations in each climatic region when we use hair cortisol level as an indicator of stress.

Effect of Dietary Rumen-Protected L-Tryptophan Supplementation on Growth Performance, Blood Hematological and Biochemical Profiles, and Gene Expression in Korean Native Steers under Cold Environment

“…Therefore, it is pivotal to establish a nutritional strategy that helps to minimize the impaired productivity of beef cattle due to temperature conditions. Cold stress causes negative effects on growth performance and immune cell population by influencing metabolic and immunological activities [5,6]. Thus, hematological profiles, if measured, could be a good indicator of how stressors affect the immune function of the body [6][7][8][9].…”

“…Cold stress causes negative effects on growth performance and immune cell population by influencing metabolic and immunological activities [5,6]. Thus, hematological profiles, if measured, could be a good indicator of how stressors affect the immune function of the body [6][7][8][9]. The thermo-neutral zone for growing Korean native beef cattle is approximately 4 to 20 • C, and the critical temperature is approximately −10 • C [1,3].…”

“…In Korea, the temperature from Nov to Feb often falls below −20 • C at night and fluctuates from approximately −5 • C to −15 • C during the daytime. Given this, adaptation to cold environments in ruminants involves increasing thermal insulation, appetite, and basal metabolic intensity that improve cold hardiness and reduce the risks of both acute and chronic cold stress [5,6,10]. Cold stress affects beef cattle production by elevating resting heat production, the energy requirement for maintenance, and appetite drive, while decreasing feed digestibility [5,7].…”

Minimally Invasive Markers of Stress and Production Parameters in Dairy Cows before and after the Installation of a Voluntary Milking System

“…Hair CORT has been shown to vary throughout the year. One study of Holstein cows found that June was associated with the highest CORT levels (13.0 ± 1.0 pg/mg, n = 18) [38], while another assessing Swiss dairy breeds identified winter as the season with the highest CORT levels (0.86 ± 0.37 pg/mg, n = 27) [11] (see Supplementary Figure S2 for comparisons). Our data agreed with the former rather than the latter, which may be linked to the maximum THI for July reaching 75.…”

“…Without multiple years being analysed, it is hard to confirm which factor caused the increase in hair CORT in the August session. If this change truly is seasonal, then this increase may not be associated with AMS and could be linked to heat stress, increased walking or changes to feeding method [30,32,38].…”