Czech J. Anim. Sci., 2023, 68(8):333-345 | DOI: 10.17221/2/2023-CJAS

Heat stress affects the milk yield, milk composition, serum oxidative status, and metabolites of Holstein cows during mid-lactationOriginal Paper

Xue Chen^1,2, Yongqiang Li^1,2, Jun Xiao^1,2, Jianan Dong¹, Wei Zhao^1,2, Zhiyi Han^1,2, Liang Xin², Guixin Qin^1,3,4, Tao Wang^1,2,3, Yuguo Zhen^1,2,3,5, Zhe Sun^3,5,6, Xuefeng Zhang^1,2,3

¹ Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Jilin Agricultural University, Changchun, P.R. China

² JLAU-Borui Dairy Science and Technology R&D Center, Jilin Agricultural University, Changchun, P.R. China

³ Jilin Provincial Key Lab of Animal Nutrition and Feed Science, Jilin Agricultural University, Changchun, P.R. China

⁴ Key Laboratory of Animal Production, Product Quality and Security, Ministry of Education, Jilin Agricultural University, Changchun, P.R. China

⁵ Postdoctoral Scientific Research Workstation, Feed Engineering Technology Research Center of Jilin Province, Changchun Borui Science & Technology Co., Ltd, Changchun, P.R. China

⁶ College of Life Science, Jilin Agricultural University, Changchun, P.R. China

Seasonal heat stress and metabolic disorders during mid-lactation are the main factors limiting production in Holstein cows, and several proteins and molecules involved in metabolic pathways are altered in response to stress. We investigated the effects of heat stress on the milk yield, milk composition, serum oxidative status, and metabolites in Holstein cows during mid-lactation to identify biomarkers associated with heat stress in serum and milk. Holstein cows with similar body condition scores (3.0 ± 0.25), parity (2.5 ± 0.5), and lactation days (115 ± 5 days) were selected in August (heat stress, HS, n = 20) 2017 and March 2018 (non-heat stress, NHS, n = 20). Milk yield was recorded daily and serum was collected on days 1, 31, and 61. Serum and milk metabolites were analysed by gas chromatography-mass spectrometry on day 1. The results showed a significantly lower average daily milk yield in the HS group than in the NHS group (P < 0.05). The milk compositions of fat (%), lactoprotein, lactose yield, and milk solid-not-fat in the HS group were significantly lower than in the NHS group on days 1, 31, and 61 (P < 0.05). The levels of  malondialdehyde were higher, whereas those of superoxide dismutase and glutathione peroxidase were lower in the serum of the HS group (P < 0.05) than that of the NHS group. The serum concentrations of d-glucose, 9,12-octadecadienoic acid, and d-lactose were significantly higher in  the NHS group than in the HS group (P < 0.05). The concentrations of lactic acid and milk urea nitrogen in the NHS group were lower than those in the HS group (P < 0.05). The present data suggest that metabolic biomarkers are closely associated with heat stress in the serum and milk, which provides a basis for evaluating indicators of heat stress occurrence in mid-lactation cows.

Keywords: lactation performance; serum and milk metabolites; oxidative stress; dairy cow

Received: November 11, 2022; Accepted: June 14, 2023; Prepublished online: August 16, 2023; Published: August 21, 2023  Show citation