Abstract:
This study is aimed to investigate the variation in hair coat characteristics and physiological
parameters of pure Jersey cows in up country wet zone and low country dry zone environment
modified farm in Sri Lanka. For this study, 30 milking cows (high and low yielders, non pregnant) from each farm were selected to obtain the data. Dry and wet bulb temperatures of
both farms were taken at morning (9.00a.m.-12.00p.m.), noontime (12.00p.m.-1.00 p.m.) and
evening (1.00p.m.-3.00p.m.) of the day to calculate the relative humidity (RH), dew point
temperature and temperature humidity index (THI). Climograph was drawn to determine the
related thermal zones for the animals of both farms. Hair coat thicknesses (mm), average hair
length (mm), number of hairs per unit area (number of hair per squire cm), hair angle to the skin
surface (inclination angle in degrees), skin fold thickness (mm) were measured to obtained hair
coat characteristics data. As physiological parameters, respiratory rates, heart rate, pulse rate,
(per min.) and rectal temperature (CO) were measured. Data underwent the analysis of Levene's
test for equal variances and the means were compared by using paired t-test by considering,
level of significance as 5% using MINITAB and SPSS. Correlations of regression between each
physiological parameter with hair inclination angles were analyzed. Relative humidity and
temperature humidity index (THI) in Dayagama farm was ranged between (87%-95%) and
(69.4-70.5) respectively; while it was (87%-93%) and (77.8- 90.5), respectively in Ridiyagama
farm. According to the THI interpretations, the milking cows of Dayagama farm were more
comfortable than the Ridiyagama farm according to the critical level of THI (72). According to
the drawn Climograph Dayagama milking cows were in thermal comfort zones while
Ridiyagama cows were in high-temperature zone. The mean values of hair coat thickness
(2.85±0.76vs 5.65± 1.67), hair inclination angle (14.45±4.49 vs 23.63±8.08) and skin fold
thickness (11.14±2.26vs9.73±2.06) Ridiyagama and Dayagama farms, respectively) were
significantly different from each other. Average hair length (13.0 ± 2.83 vs 14.73± 4.1) and hair
density (1396±597.23 vs 1445.7±651.20) were not significantly different. Except for mean
values of rectal temperature (38.48±0.40 vs38.27±0.4), heart rate (70.43±6.78vs64.66±6.84),
pulse rate (66.40±6.77 vs60.66±6.84) and respiratory rate (54.40±9.07vs41.12±6.25) were
significantly higher in cows of Ridiyagama farm. The farm level comparison between high
yielders and low yielders for each hair coat character and physiological parameter did not show
any significant difference. The climatic condition of Dayagama farm was considerably
comfortable for the milking cows than the modified climatic condition in Ridiyagama farm. Hair
coat parameters of cows showed a considerable variation based on its living climate. Yield
between two farms cannot be compared due to differences in parity, management, etc. However,
cows in both farms are able to maintain homeothermy by adapting to the region.
