The effect of low and high barn temperatures on behaviour and performance of Holstein dairy cows

The experiment was carried out at the University Training Farm in Zabcice (Czech Republic) over the period of one year (1st July to 30th June). The assessment of temperature impact was based on data from 16 hottest days (H) and 16 coldest days (L). The experimental group consisted of 70 cows in various stage of lactation (30d-210d) and parity (1-8). The cows were housed in a section (one quarter) of a free-stall barn with 77 stalls in three rows. Row A was located peripherally, close to the side wall, row B was in the middle and row C was situated centrally, close to the feed table. The cows were observed weekly on the same day at 9.00 a.m. The microclimate characteristics were recorded daily. The average values in H and L periods were as follows: temperature: 27.1 deg C and -1.47 deg C, resp., relative humidity: 54.4 % and 77.3 %, resp., THI 75 and 33, resp. Behaviour was described by a number of cows standing or lying down, number of cows lying down on their left or right side and row preference (A, B, C) in the resting area. Cow Comfort Index (CCI, number of cows lying down at given time) was calculated. A total of 1,587 observations were analysed. The number of cows lying down (922) was significantly higher than that of standing cows (665). Milk production was significantly higher in H period (by 1.0-1.7 kg). There was an interaction between period and standing. In H period the standing cows produced more milk, in L period vice versa. The cows with a non-significant tendency towards left-side laterality produced more milk (by 1.2 kg). No interaction was found between period and laterality for milk production. All the observed variables significantly differed between rows A, B and C. The row A was the most preferred, the cows preferring it were young (low number of lactation) with greatest milk production. The cows in row C had the lowest milk production and were in late lactation. There was an interaction between period and row affected number of lactation (P less than 0.01) and number of cows (P less than 0.05). In H period the row A was preferred by older cows, while in L period it was preferred by younger cows. The cows in H period used row C less while in L period they preferred it.