Effects of photoperiod and light intensity on milk production and milk composition of dairy cows in automatic milking system

Dong-Hyun Lim1, Tae-Il Kim1, Sung-Min Park1, Kwang-Seok Ki1, Younghoon Kim2,*
Author Information & Copyright
1Dairy Science Division, National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea.
2Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea.
*Corresponding Author: Younghoon Kim, Department of Agricultural Biotechnology and Research Institute of Agriculture and Life Science, Seoul National University, Seoul 08826, Korea, Republic of. Phone: +8228804808. E-mail:

© Copyright 2021 Korean Society of Animal Science and Technology. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: Mar 12, 2021; Revised: Mar 17, 2021; Accepted: Mar 19, 2021

Published Online: Apr 02, 2021


The purpose of this study was to determine the effects of photoperiod and light intensity on milk production, milk composition, hormones levels and blood metabolites indices of Korean Holstein dairy cows in automatic milking system (AMS). A total of 24 Holstein dairy cows were selected and used to four subsequent treatments for the experimental periods of 60 days. The light programs consisted of (1) Control: the natural photoperiod with 14.2 h of the light period and 9.4 h of the dark period (below 10 Lux); (2) T1: 16 hrs of the long day photoperiod (LDPP) with 50 Lux of light; (3) T2: 16 h of LDPP with 100 Lux of light; and (4) T3: 16 h of LDPP with 200 Lux of light, respectively. Importantly, there was a significant difference in the thurl activity of dairy cows between the different light intensity programs (p< 0.05). Milk yield was higher in T1 and T2 (40.80 ± 1.71 and 39.90 ± 2.02 kg/d, respectively) than those of Control and T3 (32.18 ± 1.51 and 35.76 ± 2.80 kg/d, respectively) (p< 0.05), but DMI was lower in T1, T2, and T3 compared to Control (p< 0.05). Also, milk fat percentage and the contents of milk fat and total solids were higher in T2 than those in the others (p< 0.05). The average daily melatonin level in milk was high to T3 (28.20 ± 0.43 pg/ml), T2 (24.62 ± 0.32 pg/ml), T1 (19.78 ± 0.35 pg/ml), and Control (19.36 ± 0.45 pg/ml) in order (p< 0.05). Also, the cortisol levels in milk and blood were lower in treatment groups than in Control (p< 0.05). The results of this study showed that it will be effective to improve the milk yield and milk composition, and to reduce the stress of dairy cows when the light conditions regulate to extend the photoperiod to 16 h at a light emitting diode (LED) intensity of 100 Lux under the AMS in dairy farm.

Keywords: Photoperiod; Light intensity; Automatic Milking System; Milk production; Melatonin

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