Effects of Restricting Water to Growing , Lactating and Pregnant Buffaloes Reared in a Hot and Humid Environment

An experiment was carried out to examine the effects on certain physiological indices of heat stress in buffaloes subjected to restriction of water in a hot (Atr temperature = 27.6 32.8oC) and humid (Relative humidity = 6284%) environment. Five each of growing (Mean age = 10 months). lactating (Mean milk yield = 5 litreslday) and pregnant (8 9th month of gestation) Surti buffalo& were grazed under young coconut palms and subjected to three treatments in successive periods, each of three week duration. Each treatment was imposcd 011 all g~ouys of al~irrlals irnultanenusly. In treatment t referred to as the normal management, animals were allowed drinking water ad libitum and w a h w e d for 1.5 hours daily. In treatment I1 wallowing was denied, and treatment 111 comprised restriction of drinking water in addition to denial of wallowing. Thermal stress was monitored by measuring rectal and skin temperature, respiration, pulse and cutaneous evaporation rates nf each animal several times a day. A11 physiological variabies studied showed a progressive increase from 0700 hours till 1400 hours and declined towards 1800 houn. The time effect was very highly significant (PC 0.001). Under normal management, growing heifers were found to bemorestressed than the adults. Denial of wa'lowing and restriction of drinking water caused an aggravation of heat stress wlth a n average elevation of 0.9 1.2" in rectal temperature and 16 18 respirations per mtnutc at mid day over their respective base values. No significant group difference was observed during the latter treatments. The average rate of cutaneous evaporation of 310 ' 15 during treatment I decreased to 271 t 15 g/ml/hour in treatments 11 and 111. Heifers generally showed a lower rate of cutaneous evaporation and higher rate of respiration The results indicate that despite shade the buffaloes suffered from heat stress as the ambient temperatures increased. Lack of wallowing and restriction of drinklng water aggravated the stress. Younganlmals were possibly moredependent on the pulmonary route forevaporat~vecooling. Adult buffaloes did show a capacity to lose moisture through theskin at rates comparable to those of zebu cattle.


Introduction
Buffaloes in general, show a greater affinity to water than other domestic ruminants.It is believed that the habit of wallowing in water or in wet mud plays a crucial role in the dissipation o f excess body heat, while drinking water is also known to play sonlewhat a lesser role in thermal regulatton.Tropical regions frequently encounter periods of drought when supply of adequate water becomes a problem.The combined effects of hot and humid environments of the tropics and scarcity of water may act as alimiting factor t o the survival and productivity of buffaloes maintained in such environments.In view of the envisaged plans to utilise buffalo as a major source of milk and draught power in Sri Lanka, a ~ornplete understanding of t h e interactions of the buffalo u,itlr the tropical environment should' prove useful.The present study was undertaker.to study the effects of restricting water, both for wallowing and drinkmg, under hot-humid conditions to growing, pregnant and lactating buffaloes of a recognised dairy breed.

Materials and Methods
Animals used in the experiment were chosen from the herd of Surti buffaloes on the National Livestock Developmeni Board Farm at Melsiripura.They comprised five each of growing heifers (average age = 1 0 months;weight = 140 kg), pregnant (mean age = 8 years, weight = 387 kg and in 8th to 9th month of gestation) and kctating (mean age = 8 years, weight = 344 kg and yielding 5 Litre5 of milk per day) cows.~n i m a l s -were grazed continuously on cultivated pasture -Brachiaria milformis under young coconut trees which intercepted approximately 70% of the solar radiation.They were also supplemented with cut grass in the night.Lactating animals only were provided with supplementary concentrate feed.Milking was donc twice daily at approximately 12 hour intervals.Except when required as'a parl of the experimental treatment animals had continuous access to drinking water provided in.a trough and were also wallowed in a lake between 1430 and 1600 hours each day, Animals were subjected to.the following three treatments, each treatment imposed o n all 3 groups sirnulta,neously.
Treatment I:-All animals were managed as described above; they were allowed drinking water al libitum and wallowed for 1 .S hours daily.
Treatment I1 -Same a s above but they were not allowed to wallow Treatment 111.-AnlmaIs were not allowed to wallow In addition water for dr~nking was restricted by offerlng only every &her day Each of the treatments I and IT lasted three weeks wh~le the duration of treatment 111 was 4 weeks Measurements were made during the last two weeks allowing one week for adjustment for Treatments I and JI and 2 weeks of adjustment in the case of-fieatment 111 The following'measurements were made on each animal In each treatment at 700,900, 1200, 1400 and 1800,hours.Rectal temperatures were measured by means of a clinical thermometer and resplrat~on rates by countlng flank movements S k ~n temperature was measured on the belly about 7 cm lateral to the mid l ~n e using an electric thermometer with a touch thermocouple.Cutaneous evaporation rate was ascertained from a clipped patch on the dorsal lumbar region by using cobalt chloride impregnated paper discs according to Schleger and Turner.l3 On ' standardising the technique it was found that 11.2 g water/m* paper were required to .change the colour of the disc from violet t o bright rose.
Respiration rates were measured before disturbing the an~mals.Thereafter, each animal was tied to a coconut tree and the balance measurements were made, the rectal temperature being taken last.Within a few days, the animals settled down to the 3.. procedure and showed no signs of excitement.-*

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Data from each time of observation were subjected to analysis as asplit plot in ' accordance with Gill and Hafs 5 for repeated measurements on the same animal.The -.
.f model used in this instance included the effects of groups of animals, treatment and ' ; : group x treatment interaction.Group and treatment means in each case were compared according to Duncan's multiple range test.

Results
. - The ambient temperatule and hurntdlty levels that prevuled at the location of the :-.experiment during the study period are presented in Table I.It wlll be seen that the climatic conditions were not subjected to much variation across 3 treatment periods.
-The Group -Treatment -Time of day sub class means of the different physiological '>yariables are given in Tables 2 and 3.In all treatments rectal and skin temperatures, ,"respiration, pulse and cutaneous evaporation rates showed a progressive increase up --#tho 1400 hours and showed a decline at 1800 hours (Figures 1 a to 1 e).The time effect J w a s significant (P 4 0.001) on all variables (Table 4).Although the measurements 'relate to fixed times of the day, in effect they could be related to variation in : environmental temperature and humidity.It is In terms of thelatter that the results will -be discussed.
' 3,l .Rectal temperature 3 Rectal telnpelature of growing heife~s wds found to be generally hlgher than that of .a'dult cows In Treatment I. heifels also recorded a s~gnlficanrly greater elevat~on af '+ -rectal temperatu~e Th-ere was no s~gnlf~cant treatment effect on the base values of the groups With the lestrlctlon of water, although the heifers continued to recold hglier tenipeiatules at any given tlme the elevation at h~gher alr temperatule was less (0 8%C) than thosc of pregnant and lactating cows (1 2%C).Figuics-with drffelent supelscripts within treatmenttime sub class a1 e significantly differen* (P 4 0 5 )

Skin Temperature
The mean basal skin temperature across groups and treatments was 30.02 0.3%C.Except for a significantly lower temperature of the pregnant anlmala in treatments I and 11 skin temperature did not differ among groups or treatments at any of the times.Thele was also a significant group x time interaction showing that the magnitude of change with time was not uniform across groups.

Respiration
In Treatment I and I1 the basal respiration rate averaged 22lminute with no significant differences among groups.Denial of wallowing together with deprivation of drinking water caused the basal respiration rate t o Increase significantly (Mean = 321min).Heifers had higher rates at higher temperatures.Treatments had no significant effect on the elevation of respiration rates at higher air temperatures.Groups diffcred significantly in the rise of respiration rates in Treatment 111 in the order heifers >lactating> pregnant COWS.

Pulse
A significantly higher pulse rate was observed in heifers (Mean = 65.3)compared to adults (Mean = 52.0) in treatments I and I1 only.A significant rise 111 the basal pulse rate of the adults, indicating a group x treatment interaction, resulted in the ehmination of the group differences in treatment 111.Heifers also showed a greater elevation at h~ghef alr tempera-i tures This difference in elevation was significant only at 1400 hours m treatments 11 and !111.

Cutaneous evaporation 9
Base values of cutaneous evaporation in treatment I and TI showed a significant (P (0.01) i 1 group difference with pregnant cows h a ~n g a higher rate than elther lactaflng cows or ' " 1 'the growing heifers.However, at higher alr temperatures it was seen that the two adult i gtoups lost significantly (P < 0.01) greater amounts of moisture through the skin than 1 the heifers.Restriction of water caused a general decl~ne in the rates of cutaneous ' evaporation in all three groups.maintair!hghgat balance in buffaloes.The observed changes in the different physiolggjcal parameters in association with changes in air temperature and humidity are therefore to be expected, and agree with those reported for cattle and buffaloes exposed to sun at comparable air temperatures. - Trends in rectal temperature and respiration rates in the heifers under normal ~l~allarement (Treatment I) would indicate that they were less efficient in overcoming ss,,Palll and Asker, Ragab and Ghany2 have concluded that buffalo calves uch more from heat than adults do.However, it has been shown that the increase in heat tolerance of adults is interrupted by lactation and pregnancy.' .' Enhanccd heat production due to increased metabolism in the latter categories of aniEi~ls.riiake them more vulnerable to heat stress.Our results, therefore are at varianee from expectations.Conditions in treatment 1 probably had only mild effects vas seen that the trend reversed in treatments I1 and 111 resulting in the adults :qually or much more stressed than heifers.
for it v being ( it,i$ believed that buffaloes have a poor capacity to sweat due to a relative paucity ofi.weat glands.Hafez, Badreldin and Shafei6 calculated the area of glandular surface per unit area of skin to be only a third of that in cattle.Nevertheless, rates of LUL~IIFUJS evaporation in Murrah buffaloes almost similar to certain breeds of zebu cattle hawedbeen observed at air temperatures of 400C.7 Therates recorded in our study are sirnilat0 those of the above study but higher than those of swamp buffaloes reported bftMoran!O In this context it is also noteworthy that thesite of measurement in the present study -the dorsal lumbar region is noted to be thearea with thelowest density of sweat glands in the buffalo6 whereas Moranlo measured in the shoulder region uih~ich has a much greater density.Furthermore our observation of a lower rate of moi$$ute loss in the heifers is in contrast with the reports that the sweat gland density, ,ahd therefore the sweating capacity in buffalo decrease with age:g Genetic differences of the animals used, differences in site of measurement and in environaental conditions are likely factors responsible for the inconsistencies.Ho*wever, it is also possible that all of the moisture was not due to true sweating but partly due to insensible loss of moisture by diffusion through the epidermis.Latter has been re~ognised to contribute significantly to moisture loss in a variety of animak4 The decline in cutaneous evaporation associated with restriction of water may also supp~rt,this explanation.Buffalo calves have a relatively more hairy coat.It is possible that diffusion of moisture is therefore, interfered with to some extent unlike in the ad'ules, and the pulmonary route assumes greater importance in evaporative cooling in the kifiors.This may explain the lower rate of cutaneous evaporation and higher respi+~zidon rates in the heifers.
'.It was readily apparent that denial of wallowing caused the lactating and pfieg~@Ent animals to be more stressed whereas heifers were affected to a lesser extent.
Data an water metabolism showed that there was a dramatic increase In water turnover rates during this period (Ranawana, Tilakaratne, Snkandakumar, unpublished data) This was probably due to ~ncreased water intake as an attempt to compensate for the lack of wallowing.Apparently ~t dld not help the an~mals to a notable degree.Thus the results underline the Importance of wallowing to the buffalo as a means of cooling themselves.
In treatment 111, when drinking water was restricted along with decline of wallowing it was seen that the heat tolerance was further affected and thermal stress aggravated, no doubt part of it was due to carry over effect from Treatment 11.It must also be borne in mind that there 1s some confounding of treatment effects with the physiological status of pariicularly the lactating and pregnant cows.The advancing foetus of the pregnant animals wo~lid be expected to cause additional heat load while the milk yield of lactating cows was likeIy to decline with advancing Aages of lactation resulting in a lesser heat load.In fact a progressive drop in average milk yield was observed (Period I = 5.24,I I = 3.68andI I ~= 2.39 Liday) with thetreatment differences being significant (P 4 O.OI).This decline, however, was evidently brought about by treatment effect since it was notedthat the milk yield began to increase a week after the termination of the trial.The effects on milk yield'were probakly due to reduced feed intake as a result of thermal stress.
.Surti is a bre.ed of buffaloes developed in the North Western regions of India where the climate is extreme in both winter and summer.The present results however would indicate that this breed is not well adapted to an environment of high air temperature and humidity.This aspect needs to be considered in the choice of breeds of buffaloes for rearing under such conditions.Climatic stress was aggravated by denial of w'allowing and restriction of drinking water which underlines the need.forprovision of facilities for wallowing or any other means of wetting.Another notable finding of-the present study is that in contrast to theaccepted.concept,buffaloesdo Lose a significant amount of moisture through the skin.This capacity is relatively less in young.anirnals in whom pulmonary evaporation seems to be more important.
Analysis of data 3-Separate analyses wele perfo~nied within each treatment-period to asce~tam the effects f of time of observation within treatment.

Figuics
Figure I e. Cutaneous Evaporation Rates of Growing (o

I
Shade is considered t o be a n important factor i n ameliorating climatic stress in buffaloes.However, a s reflected by rectal temperature and respiratory responses it was evident that .theanimals in this study, despite some protection from direct .sunlight, were subjected t o thermal stress as the environment became warmer.Evaporation of water through pulmonary and cutaneous routes is known to play a significant role i n heat loss3 in mammals, while Pandey and Roy12 considered respiratory evaporation t o be of greater importance t h a n other mechanisms in : I Water to Growzng, Lactating and Pregnnnt Buffa!oes 3 7