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Circadian variations in heat production and heat loss in Murrah buffaloes during different season Vaidya, M.; Kumar, P.; Vir Singh, V.S.. Keeping the hypothesis in mind, 6 each of growin

Circadian variations in heat production and heat loss in Murrah buffaloes during different season

Vaidya, M.; Kumar, P.; Vir Singh, V.S.

Dairy Cattle Physiology Division National Dairy Research Institute, Karnal -132001 (India)

ABSTRACT

Rhythmicity in physiological parameters is an important process both as convenient and reliable markers of operation of the biological clock and as an indicator of general health of an animal Keeping the hypothesis in mind, 6 each of growing (8-12 months) and adult (18-24 months) female Murrah buffaloes were selected from NDRI herd to monitor the circadian physiological functions during winter (Dec- Jan), spring (Feb-March) and summer (April-May) season Physio-logical functions were recorded at 4.00 hrs interval i.e 6.00, 10.00, 14.00, 18.00, 22.00 and 2.00 hrs PhysioPhysio-logical responses [respiration rate (RR), rectal temperature (RT), skin temperature (ST) and pulse rate (PR)], oxygen consump-tion, heat production and heat loss through sweating and panting were recorded at four hourly intervals round a day Environmental variables viz dry bulb and wet bulb temperature, relative humidity, minimum and maximum temperature, wind speed was also recorded at the same interval and THI was calculated Physiological responses (RR, RT, ST and PR) increased significantly (p<0.01) during

spring and summer season compared to winter in both growing and adult buffaloes Oxygen consumption of growing and adult Murrah buffaloes was found to be significantly higher (p<0.01) at 14.00 hrs than at 2.00 hrs during summer compared to spring and winter Heat storage and heat production differed significantly (p<0.01) among adult and growing buffaloes during spring and summer season Heat loss through skin and pulmonary system was higher (p<0.01)

in adult compared to growing buffaloes during summer Significantly higher (p<0.05) heat load was observed in adult compared buffaloes during summer THI showed a positive correlation with physiological responses, oxygen consump-tion, heat producconsump-tion, heat storage and negative with heat loss The circadian rhythmicity in physiological functions with change in environmental variables was found to be maximum at 14.00 hrs which enabled Murrah buffaloes to maintain the thermal balance Therefore, buffaloes required special protection particularly during summer stress (10.00

to 16.00 hrs) for maintaining normal physiological conditions and productivity

Keywords: circadian, variations, buffaloes

INTRODUCTION

Rhythmicity of physiological parameters in farm animals is important from an economic perspective because knowledge

of these processes can lead to improvements in stress and disease management through better knowledge of animal's rhythmic behavior, with respect to environmental variables In order to find out the rhythmicity in heat production and heat loss in Murrah buffaloes during different seasons present study was carried out

MATERIALS AND METHODS

Twelve Murrah buffaloes were selected from the NDRI, Karnal herd and further divided equally into two groups i.e growing (8-12 months) and adults (24-48 months) The study was conducted during winter, spring and summer season The physiological parameters viz rectal temperature (RT), respiration rate (RR), pulse rate (PR) and skin temperature (ST); oxygen consumption, heat production (oxygen consumed) and heat loss through sweating and panting were recorded at 4-hourly intervals during 24 hours a day The oxygen consumption (Vo2) was recorded by using modified Benedict-Roth-Collins Spirometer Heat loss through skin was measured using ventilated capsule method5 Heat loss through respiratory tract was measured by ventilated mask method The environmental variables viz minimum and maximum temperature, dry and wet bulb temperature, relative humidity were recorded at the similar intervals and temperature humidity index (THI) was calculated The data were analyzed statistically using suitable statistical models

RESULTS AND DISCUSSION

Physiological responses:

During winter, spring and summer season, the RT increased by 1.40C, 0.70C and 0.90C in adult and 0.8 0C, 0.80C and 1.20C in growing Murrah buffaloes at 2.00pm compared to 2.00am, respectively (Fig.1) The RR increased by 4.0, 7.0 and 8.0 breaths/min at 2.00pm over 6.00am in adult Murrah buffaloes during winter, spring and summer season respectively Almost similar increasing trend in RR was observed in growing buffaloes (Fig.1) The PR increased by 8, 5.5 and 6.0 beats /min and 5,5 and 10 beats /min in adult and growing Murrah buffaloes at 2.00pm compared to 2.00 am during winter, spring and summer season respectively (Fig.2) RT RR and PR recorded during afternoon and night differed significantly (p<0.01) in both the groups of buffaloes Increase in all the physiological responses was recorded as the ambient temperature increased in both the group of animals maintained inside and outside the shelter 6, 7 Circadian change in the heart rate of Murrah buffalo calves and adults3

During winter, spring and summer season, ST was increased by 9.30C, 70C and 10 0C; 7.10C, 50C and 9.20C in adult and growing Murrah buffaloes at 10.00am compared to 6.00am respectively (Fig.2) The overall mean values varied signifi-cantly during spring Diurnal variation in skin temperature of different body parts was reported in response to heat stress

in male buffalo3

RT (0C RR (breaths/min)

Fig.1: Circadian variations in RT

(0C) and RR (breaths/min) of adult

and growing Murrah buffaloes

dur-ing different seasons

PR (beats/min) ST (0C)

Fig 2: Circadian variation

varia-tions in PR (beats/min) and ST

(0C) in adult and growing Murrah

Buffaloes during different seasons

1 Amakiri, S.F and Funsho, O.N 1979 Studies on rectal temperature, respiratory rate and heat tolerance in cattle in humid tropics Animal Prod, 28: 329-335.

2 Brody, S 1945 Bioenergetics and growth Reinhold Publ Corp., New York, U.S.A.

3 Das, S.K, Upadhyay R.C and Madan, M.L 1999 Heat stress in Murrah buffalo calves Livestock Prodn Sci 61: 71-78.

4 Finch, V.A 1985 Comparison of non evaporative heat transfer in different cattle breeds Australian J Agri Re, 36: 497-508.

5 McLean, J.A 1963a Measurement of cutaneous moisture vaporization from cattle by ventilated capsules J Physiol 167: 417-426

6 Salam, I.A 1980 Seasonal variation in some body reactions and blood constituents in lactating buffaloes and Friesian cows with reference to

acclimatization J Egyptian Vet Med Association, 40:63.

7 Soly, M.J 2001 Physiological and hematological responses of crossbred males under different housing conditions M.Sc Thesis, NDRI Deemed

University, Karnal (Haryana), India.

8 Thakur, T.C Singh, M.P and Singh B 1989 Studies on physiological responses of man and animals with different tillage tools under field

conditions Indian J Dairy Sci 42:332.

During winter, spring and summer, oxygen consumption increased significantly (p<0.05) by 0.45, 0.45 and 2.1 in adult and 0.66, 0.66 and 0.8 l/m growing Murrah buffaloes at 2.00pm compared to 2.00am (Fig.3) During winter, spring and summer season, heat Production increased significantly (p<0.05) by 588, 1640 and 2597 kJ/h in adult and 1226, 755 and 970 kJ/h in growing buffaloes at 2.00pm as compared to 2.00am Heat production in animals has been shown to vary with environmental temperature2 During spring and summer heat loss through skin increased significantly (p<0.05) by

485 and 1041 in adult and 100 and 308 kJ/h in growing Murrah buffaloes at 2.00pm as compared to 2.00am (Fig.4) During summer the heat loss through pulmonary system increased significantly (p<0.01) by 240 and 127 kJ/h in adult and growing Murrah buffaloes respectively at 2.00pm as compared to 2.00am Evaporation from the skin is the major route of heat dissipation in cattle exposed to hot environment as compared to pulmonary evaporative losses4

SUMMARY AND CONCLUSION

The physiological responses (RT, RR, PR and ST) and heat production increased significantly (p<0.01) at 2 pm as compared to respective values at 2 am in both adults and growing buffaloes during different seasons Heat loss through the skin was found to be major route accounting for about three forth of the total heat loss The result of the study indicated suitable manangemental practices should be followed for reducing thermal heat load

Fig 3: Variation in Vo2 (l/min)heat

production (kj/h) in adult and

growing Murrah buffaloes

Fig 4: Variation in heat loss

through skin and heat loss through

pulmonary system (kJ/h) in adult

and growing Murrah Buffaloes

dur-ing different seasons

Comparison of Bodyweight and Body Size

of Growing Buffaloes between Large and

Small Scale Farms in Nepal

Hayashi, Y.1; Shah, M K.2; Kumagai, H.3; Shah, S K.2

1Experimental Farm, Faculty of Agriculture, Meijo University Postal Address: 4311-2, Hishigaike, Takaki-cho, Kasugai, 486-0804 Japan 2Institute of Agriculture and Animal Science, Tribhuvan University, Rampur, Chitwan, Nepal.3Graduate School of Agriculture, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 606-8502 Japan *The study was supported by a fund for research project in 2007 from Meijo Asian Research Center and a grant-in aids for scientific research

(No 19405041) from the Japanese Society for the Promotion of Science (JSPS) E-mail: yoshiha@ccmfs.meijo-u.ac.jp

ABSTRACT

The bodyweight (BW), body length (BL), withers height (WH), criss-cross height (CH), heart girth (HG) and hip width (HW) in the total 143 head of growing buffaloes raised by a large-scale farm (LF) in Kaski and small-scale farms (SF) in Chitwan were measured for presenting the growth differences of the buffaloes in Nepal The development of the body measurements, the BW ratio (BWR) and the withers height ratio (WHR) of each body trait was compared between LF and

SF The phenotypic correlation coefficient between every pair of traits in the buffaloes was calculated The maximum of

BW, BL, WH, CH, HG and HW in the buffaloes less than 24 months old of LF reached to 365.0 kg, 123.8 cm, 123.5 cm, 126.3 cm, 169.0 cm and 47.5 cm, respectively On the other hand, the corresponding values of SF reached to 200.0 kg, 109.8 cm, 113.2 cm, 115.0 cm, 140.0 cm and 37.0 cm, respectively The following equations to show the average BW (kg) with age of month (AM) in the buffaloes of LF were calculated: The male BW=9.79AM+50.14; The female BW=9.21AM+41.11 The corresponding equations of SF were as follows: The male BW=6.88AM+30.03; The female BW=5.31AM+38.85 The development of the buffaloes was faster in LF than in SF The BW of the 24 months old buffaloes calculated by the equations differed around 90 kg between LF and SF The BWR in male and female had higher average values in SF than in

LF (P<0.01) The mean WHR of BW, BL, HG and HW was higher in LF than in SF (P<0.01) However, the average WHR of CH

in SF was higher than that in LF (P<0.01) The correlation coefficient between BW and HW was 0.97 in the both sex (P<0.01) The comparison indicated that the improvement of feeding and breeding managements in buffaloes was still required for the efficient growth of buffaloes in SF

Keywords: body size, bodyweight, buffalo, comparison, growth, Nepal

INTRODUCTION

Buffaloes are essential animals which have been raised for draught and dairy in Nepal In addition, the consumption of milk and meat produced by buffaloes has been increasing in Nepal1, 2) As Nepalese do not eat beef due to their religious reasons, buffaloes are remarkable for the meat production in the country Therefore, the improvement of growth rate in buffaloes is required for efficient dairy and meat production A few studies on body size variation of growing buffaloes have been conducted3, 4) Although there are different developments of buffaloes between large-scale and small-scale farms, the variance of the growth remains obscure Hence, the present study is conducted to compare the body dimen-sion of growing buffaloes raised by large-scale and small-scale farms

MATERIALS AND METHODS

The total 143 head of buffaloes which unused for dairy and drought raised by a large-scale farm (LF), Livestock Development Farm in Lampatan, Kaski and private small-scale farms (SF) in Chitwan were selected for the survey from July 2007 to March

2009 The bodyweight (BW), body length (BL), withers height (WH), criss-cross height (CH), heart girth (HG) and hip width (HW) of the growing buffaloes, the BW ratio (BWR) and the withers height ratio (WHR) of each body trait was compared between LF and SF The values of age, BW and WH were used for the regression analyses to establish the formulae to estimate

BW and WH with age in the growing buffaloes The phenotypic correlation coefficient between every pair of traits in the buffaloes was calculated The present study was carried out with the regard to the ethical treatment of animals

RESULTS AND DISCUSSION

Totally 84 and 59 head of buffaloes in LF and SF were studied, respectively The breed of buffaloes was Murrah and Murrah-cross Sixty five percent of the total buffaloes were born from June to October when pasture was available to be taken by the animals5) The buffaloes were considered to have a seasonal breeding The age of the buffaloes was from 4 to 24 months old in male and from 5 to 24 months old in female The maximum of BW, BL, WH, CH, HG and HW in the buffaloes

of LF reached to 365.0 kg, 123.0 cm, 123.5 cm, 126.3 cm, 169.0 cm and 47.5 cm in male, and 319.0 kg, 123.8 cm, 120.6

cm, 123.3 cm, 150.0 cm and 46.0 cm in female, respectively On the other hand, the corresponding values of SF reached

to 200.0 kg, 108.8 cm, 108.2 cm, 112.6 cm, 135.0 cm and 37.0 cm in male, and 176.0 kg, 109.8 cm, 113.2 cm, 115.0

cm, 140.0 cm and 36.0 cm in female, respectively The following equations to show the average BW (kg) with age of month (AM) in the buffaloes of LF were calculated: The male BW=9.79AM+50.14; The female BW=9.21AM+41.11 The corresponding equations of SF were as follows: The male BW=6.88AM+30.03; The female BW=5.31AM+38.85 The develop-ment of the buffaloes was faster in LF than in SF The BW of the 24 months old buffaloes calculated by the equations differed around 90 kg between LF and SF (Figure 1) The formulae to estimate WH with AM in the buffaloes of LF were as follows: The male WH=1.45AM+85.73 The female WH=1.34AM+85.61 The corresponding formulae of SF were calculated: The male WH=1.71AM+73.86 The female WH=0.92AM+81.42 (Figure 2) The BWR and WHR of each body trait of the buffaloes in LF and SF were shown in Table 1 and 2, respectively The BWR in male and female had higher average values

in SF than in LF (P<0.01) This condition indicated that the proportion of BW with body size in SF was lower than that

in LF The mean WHR of BW, BL, HG and HW was higher in LF than in SF (P<0.01) However, the average WHR of CH in SF was higher than that in LF (P<0.01) The results indicated that the body of buffaloes in SF was thinner than that in LF The development of body was considered to be slower in SF than in LF The phenotypic correlation coefficient between every pair of traits in the buffaloes in LF and SF was shown in Table 3 The every pair of traits had high correlation (P<0.01) The correlation coefficient between BW and HW was 0.969 and 0.966 in male and female, respectively The possibility of efficient growth in buffaloes with the improvement of feeding and breeding in SF was suggested Although the BW is usually estimated using HG, HW is also assumed to be the effective body trait for BW estimation of growing buffaloes

1 Food and Agriculture Organization of the United Nations (FAO) 2005 Livestock Sector Brief, Nepal Livestock Information, Sector Analysis

and Policy Branch, Rome, Italy.

2 Food and Agriculture Organization of the United Nations (FAO) 2008 FAOSTAT [cited 28 December 2009] URL: http://faostat.fao.org/site/

569/default.aspx#ancor

3 Hayashi Y, Shah MK, Tabata Y, Kumagai H, Shah SK 2008 Feeding trait and body dimension of growing buffaloes raised by small-scale farms in

Tarai, Nepal Proceedings CD of the 13th Animal Science Congress of the Asian-Ausralasian Association of Animal Production Sciences (2.Ruminal nutrition, feeding and management, Oral, 08).

4 Hayashi Y, Shah MK, Kumagai H, Shah SK 2009 Body weight and body size of growing buffaloes raised in Nepal Pakistan Journal of Zoology

9: 143-145.

5 Hayashi Y, Maharjan KL, Kumagai H 2006 Feeding traits, nutritional status and milk production of dairy cattle and buffalo in small-scale farm

in Terai, Nepal Asian-Austral Asian Journal of Animal Sciences 19: 189-197.

Acknhowledgements:

The study was supported by a

fund for research project in

2007 from Meijo Asian

Re-search Center and a grant-in

aids for scientific research (No

19405041) from the Japanese

Society for the Promotion of

Science (JSPS)

Table 1: Bodyweight ratio (BWR) in the buffaloes less than 24 months old

Table 2: Withers height ratio (WHR) in the buffaloes less than 24 months old

Table 3: Phenotypic correlation between every pair of traits in the buffaloes

Male above the diagonal and female under the diagonal P<0.01.

ab: P<0.01 ab: P<0.01

Effect of the climatic conditions of the brazilian eastern amazon in the tolerance to the heat in buffaloes (bubalus bubalis) created on the

shading and sun

Silva, J.A.R.1; Santos, N.F.A.2; Araújo, A.A.3; Lourenço Júnior, J.B.4; Garcia, A.R.5; Viana, R.B.6;; Nahúm, B.S.5.

1 Graduate degree of Rural Federal University of Amazonia - UFRA - Tv Tancredo Neves, s/n Belém, Para State, Brazil DSc Student in Zootecnic, Federal University of Ceara UFC e-mail: jamileandrea@yahoo.com.br 2 DSc Student in Agricultural Sciences, Rural Federal University of Amazonia - UFRA Tv Tancredo Neves, s/n Belém, Para State, Brazil.

3 Postgraduate degree of Federal University of Ceara UFC Av Paranjana, 1700 Campus do Itaperi, Fortaleza, Ceara State, Brazil 4 Postgraduate degree of Federal University of Para State -UFPA and Federal Rural University of Amazonia - UFRA - Tv Dr Eneas Pinheiro s/n Belem, Para State, Brazil - 5 Researcher Embrapa Eastern Amazon Tv Dr Eneas Pinheiro s/n Belem, Para State, Brazil - CEP 66.095-100 6 Graduate degree of Rural Federal University of Amazonia - UFRA - Tv Tancredo Neves, s/n Belém, Para State, Brazil.CEP 66.095-100.

ABSTRACT

The effect of the climatic conditions of the Brazilian Eastern Amazon on the rectal temperature (RT), respiratory

frequen-cy (RF) and index of tolerance to the heat (ITH) - Benezra was evaluated, 20 female buffaloes of the Murrah race, entirely randonized distributed, in two experimental groups (Group Without Shading - WS and Group With Shading - S), in silvopas-toral system, with Brachiaria humidicola, in rotationed grazing The buffaloes of Group S (n=10) had remained in pasture shadings for the leguminous Acacia mangium, while of Group WS (n=10) was kept in pasture without access to the shade All the animals had access to the water to drink and mineral salt "add libitum" The period of adaptation of the animals to the systems was of 14 days The physiological variable was taking in two turns in the morning (7 AM) and in the afternoon (13 PM) The statistical analysis presented differences significant (P<0.05) between the turns, for the two treatments, the

RT of the turn in the afternoon, 38.6 and 38.8ºC, respectively of Groups WS and S, was superior to temperatures takes in the morning, 38.4 and 38.4ºC The RF, in Group WS, in the turn of the afternoon, was different (P<0.05) between the months, with bigger values in May (38 movement/minute) and lesser in June (31 movement/minute) The average values of the ITH only showed differences between the turns of the morning (2.24) and the afternoon (2.46)

Keywords: Bioclimatology, physiological variable, rectal temperature, respiratory frequency,

silvopastoral system, Brachiaria humidicola

INTRODUCTION

The climate of the Eastern Amazon Region is characterized for presenting high temperatures and relative humidity of the air These climatic conditions are a challenge for the homoeothermic animals that has difficulties in wasting heat to restore its thermal balance corporal The buffaloes, pertaining to this group, have specific structural characteristics, with raised concentration of melanin in the skin, reduced amount of sweat glands and density of hair, what it becomes very sensible to the direct solar radiation Being thus, this research aims to evaluate the effect of the availability of shade of trees (leguminous Acacia mangium), in two periods of the day (7 A.M and 1 P.M.) in the rectal temperature, respiratory frequency and index of tolerance to the heat of buffaloes of the Murrah race, in the climatic conditions of the Eastern Amazon Region

MATERIALS AND METHODS

This Work was lead in the Unit of Research "Senator Alvaro Adolpho" (01°.26'.03" S and 48°.26'.03" W), Belem, Para State, Brazil, pertaining to the Embrapa Eastern Amazon, of January to June 2009 The local climatic type is the Afi, according to Köppen The pluvial precipitation annual average is 3,001 mm, annual average relative humidity of air 85%, annual average temperature 27ºC and 2,400 hours of annual insolation 2.Were used 20 Murrah buffaloes, between four and five years old, average weight 359kg, cyclical, non-lactating The animals were distributed, randomized, in two experimental groups (Group S - with shade and Group WS - without shade) The period of adaptation was of 14 days Group S (n=10) remained in rotation pasture, in poles with shade of trees of the leguminous Acacia mangium, in silvopastoral system, while Group WS (n=10) was kept without access to the shade, also, in rotation pasture The feeding was of the pasture "quicuio-da-Amazônia" (humidicola Brachiaria), with access the water to drink and mineral salt ad libitum The studied physiological variable, rectal temperature (RT) and respiratory frequency (RF) was surveyed two times per week, to 7:00 A.M and 13:00 P.M., with the aid of clinical thermometer veterinarian, with scale until 44ºC, and for the inspection and counting of the thorax-abdominal movements, during one minute (movement/minute) The Index of tolerance to the heat of Benezra 3 was used, values next the two (2.0) indicate that the animals are adapted

to the environment The calculation was effected using the formula: ITH = RT/38.33 + RF/23, where RT: rectal tempera-ture and RF: respiratory frequency The climatic variable referring to the temperatempera-ture of air (AT) and relative humidity of air (RHA) were gotten in the Meteorological Station of the INMET - 2º DISME, located the 500 meters of the experimental area, and from them, was calculated the Index of Temperature and Humidity (ITH) 8: ITH: [0.8 x T + (RH/100) x (T-14.4) + 4.4], where: T = temperature (ºC) and RH = relative humidity of air (%) Descriptive analyses and of variance were made, 0.05% of significance, in the SYSTAT, version 12

RESULTS AND DISCUSSION

The averages of climatic variable and the index of temperature and humidity, in the experimental period, per the morning and to the afternoon, are in Table 1

Table 1 Average values of the relative humidity of

air (HRA), temperature of air (AT) and index of

temperature and humidity (ITH), of January to

June of 2009, in Belem/Para State, Brazil

In Figure 1 is illustrated the variation of the RT in the experimental period Significant differences (P<0.05) between averages of the turns and treatments had been observed, with 38.6 and 38.8ºC, in Groups WS and S, per the afternoon, superiors to the the morning, 38.4 and 38.4ºC

Figure 1: Variation of rectal temperature of buffaloes created

without shade (WS) and shade (S), of morning (7:00 A.M.) and to

the afternoon (1:00 P.M.), in Eastern Amazon.

Figure 2: Variation of respiratory frequency of buffaloes

cre-ated without shade (WS) and shade (S), of morning (7:00 A.M.) and to the afternoon (1:00 P.M.), in Eastern Amazon.

In the experimental period had significant differences (P<0.05) in all months, between Groups WS and S and turns In Group

WS, in both the turns, had significant difference (P<0.05) between the months, with lesser values in June (38.55ºC), that it can have occurred due to adaptation acquired for the animals, in elapsing of the period of collection of data, when they presented differentiated behavior, in mud puddles formed by the water of rain In them, the animals lay down, in order to keep the body temperature in normal levels, considering it that in this group it did not have shade availability This behavior was waited, therefore as research executed in São Paulo State, Brazil 1, buffaloes has preference for water for bath, when they desire

to thermorregular In both the studied groups, the RT was significantly superior in the turn of the afternoon, when the ambient temperature if found higher Research in Rondônia State, Brazil, with buffaloes created in silvopastoral system 6, had presented resulted similar, where the RT passed of 38.7ºC for 39.2ºC, per the morning and late, respectively, what demonstrates that the rise of the ambient temperature influences in this physiological variable The variation of the RF of the animals studied, during the experimental period, is presented in Figure 2 In March and April had significant differences (P<0.05) between Groups WS and S and turns In January, February, May and June the differences (P<0.05) had been only between the turns In Group WS,

to the afternoon, the difference (P<0.05) occurred between the months, with bigger values in March (38 mov./min.) and minors in June (31 mov./min.) These results are in accordance with literature 9 In pasture without shade, the buffaloes present significant rise in the RT, of 38.3 for 39.1ºC, and in the RF, of 22.6 for 48.4 mov./min., as form to waste the excess of corporal heat, in result of thermal stress, that it harms its productive performance 7 The daily average value of the index of tolerance to the heat of Benezra was 2.32, in Group S, and 2.38, in Group WS Per the morning and to the afternoon, the average results were, respectively, 2.22 and 2.41 (Group S) and 2.25 and 2.50 (Group WS) The variance analysis disclosed differences significant (P<0.05) of the index, in Group WS, to the afternoon, probably due to rise of the ambient temperature and the direct solar radiation on the skin of the animals, since they did not have availability of shaded areas to be protected

Figure 3: Index of tolerance to the heat of

Benezra, in the experimental period.

In January, March and April had differences (P<0.05) between Group S and WS and turns In February, May and June the difference (P<0.05) was only between turns The averages of the index of tolerance to the heat of Benezra, in the experimental period, are in Figure 3 Similar results had been gotten in Eastern Amazon 4, where it was observed that the ITH of the animals kept in the system with shade is next the 2,0, in 70% of the carried through comments, what it proves the importance of the shade in the animal ambience, tropical climates, as of the Brazilian Amazon In Table 2 are the average results of the rectal temperature, respiratory frequency and index of tolerance to the heat of Benezra, in buffaloes created to the shade and the sun, per the morning and to the afternoon

Table 2: Averages of the rectal

temperature, respiratory

frequen-cy and index of tolerance to the

heat of Benezra (ITH), buffaloes

created to the shade and the sun,

per the morning and to the

af-ternoon, in Belem, Para State,

Brazil

The systems that allow access to the shade, as the silvopastoral, promote better tolerance of the buffaloes to the tropical heat, in comparison to the kept in area without shade The simple shade in the pastures can have positive consequences in the productivity of the buffalo, although the temperature, relative humidity of air and index of temperature and humidity

to affect the physiological variable and the index of tolerance to the heat, mainly, in the period of the afternoon

Acknowledgements.

To the Supervision of Development of Amazon - SUDAM, for the financial resources To the Embrapa Eastern Amazon, for the availability of the area and experimental animals To the National Institute of Meteorology - INMET/2º District of Meteorology, for the supply of the climatic data

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