BEHAVIOURAL RESPONSE TO DIFFERENT CLIMATIC CONDITIONS OF BEEF CATTLE IN INTENSIVE REARING SYSTEMS

ISSN 133-7142 UDK = 636.2.33:636.83.31 BEHAVIOURAL RESPONSE TO DIFFERENT CLIMATIC CONDITIONS OF BEEF CATTLE IN INTENSIVE REARING SYSTEMS Mrt Brscic, Flvin Gottrdo, A. Mzzeng,, G. Cozzi Originl scientific pper SUMMARY The study imed to evlute the ehviour of eef cttle rered in intensive systems in northern Itly under different climtic conditions. In prticulr, it considered 3 levels of THI (Temperture-Humidity-Index) in order to evlute the coping response to het stress conditions regrding chnges of eef cttle nutritionl nd socil ehviours, drinking frequency nd resting time. Behviourl oservtions were crried out from July to Octoer 25, during hot (THI ove 78), mild (THI 76) nd cool (THI elow 72) conditions, on 24 finishing French crossred ulls. The nimls were housed in 6 fully sltted floor group pens of 4 ulls ech. Within ech clss of THI, ehviours were recorded in two sessions of 24 hours using 5 ute intervl scn smpling technique. A focl niml ws chosen in order to count the numer of visits t the wterer. Results showed tht eting ehviour ws mximum during the first 8 hours fter fresh feed delivery. However, in the sme intervl, when THI ws ove 78, eting ctivity ws penlized while n increse of ruting ws oserved. The overll numer of visits t the wterer ws incresed y the het stress condition nd they were minly concentrted in the hottest hours of the dy. Hot environment lso ffected eef cttle socil ehviour incresing gonistic interctions nd mounts mong penmtes. Since het stress ffected ulls ehviour impiring their welfre, the doption of cooling devices should e recommended. Key-words: eef cttle, temperture humidity index, heth stress, ehviour INTRODUCTION The report on eef cttle welfre, edited y the Scientific Committee on Animl Helth nd Animl Welfre (21), suggested tht the highest threshold temperture gurnteeing sustinle welfre condition for this ctegory of nimls is up to 3 C when humidity is elow 8% while it flls under 27 C if the humidity level is higher. Therefore, in order to identify potentil conditions of het stress t the frm level Temperture-Humidity-Index (THI) should e considered insted of temperture nd humidity seprtely (NOAA, 1976). THI is commonly pplied to estimte het stress in diry cows. When THI vlues were ove 75, cows showed physiologicl signs of stress such s incresed ody temperture nd modifiction of herth nd respirtory rtes (Aeni et l., 1993). The sme environmentl conditions modified lso diry cttle feeding ehviour nd resting. The vritions of feeding ehviour led to reduced dry mtter intke ffecting consequently milk production (Bernucci nd Clmri, 1998). Similrly to diry cttle, studies crried out on feedlot eef cttle exposed to hot environment, showed reduced feed intke nd worsened growth performnces (Mitlöhner et l., 21; Brown-Brndl et l., 26). None similr investigtion hs een crried out on eef cttle rered indoors in intensive systems. Despite, this type of housing is distriuted over most of the Europen Countries nd is predont in north Itly for the fttening of out 2 millions of ulls ech yer (Cozzi nd Rgno, 23). Climtic conditions in northern Itly, during summer, re very often dverse for niml welfre nd therefore the present study imed to evlute ehviourl response of this ctegory of cttle to different levels of THI. MATERIAL AND METHODS Mrt Brscic, PhD student; PhD. Flvin Gottrdo, Associted Professor; Alessndro Mzzeng, PhD. student; PhD. Giulio Cozzi, Full Professor - Deprtment of Animl Science - Università degli Studi di Pdov, Vile dell Università 16, 352 Legnro (PD), Itly 1

The ehviourl study ws crried considering three different microclimtic conditions: THI elow 72, THI = 76 nd THI ove 78. THI elow 72 is considered the therml neutrl zone, THI of 75-76 flls in the intervl of mild het stress, while THI ove 78 ws the imum threshold of het stress considered dngerous for the nimls (Armstrong, 1994). In order to find these environmentl conditions the study ws extended from July to Octoer 25 nd experimentl dys were decided on the sis of the forecst of the locl gency for the wether control. The tril ws crried out in n intensive commercil frm locted in Brugine - Province of Pdov which fttened 18 eef cttle/yer. Behviourl oservtions were performed on tch of twentyfour French crossred ulls, housed in six group pens lnced for their initil ody weight (58 ± 47 kg). The pens hd fully sltted floor nd the spce llownce ws 4.5 m 2 /hed. Bulls were fed d liitum the sme totl mixed rtion (TMR), distriuted once dy t 9:3 AM. The diet ws sed on mize silge nd ws formulted (Crude protein = 13.3 % DM; NDF = 31.6 % DM; Non-firous Crohydrtes = 45.2 % DM) in order to cover the nutritionl requirements for hypotheticl verge dily gin of 1.3 kg/hed (INRA, 1988). All the nimls hd free ccess to fresh wter, provided y one pressure-wterer per ech pen. Two dys of oservtions were dedicted to every THI condition considered in the study (Hot, Mild nd Cool). Ech session strted in the morning fter feed delivery nd lsted for 24 hours. Direct oservtions of the nimls were crried out y trined personnel using scn smpling technique with 5 intervl etween scns (Mrtin nd Bteson, 1993). At ech scn the numer of nimls per pen lying, resting, eting nd ruting ws recorded. The numer of socil events such s fights nd mounts per pen were noted using the ehviour smpling technique while the numer of visits t the wterer ws recorded just for the focl niml (Mrtin nd Bteson, 1993). The sujects chosen for the focl smpling were the esiest ones to distinguish mong the penmtes. Behviourl dt otined from scn smpling, were expressed in utes ssug tht ech ehviour persisted for the entire 5 utes scn intervl (Mekw et l., 22). Events relted to socil ehviour (mounts nd fights) nd wter consumption occurrences were considered s numer of events. Dt were nlysed y PROC GLM (SAS, 199) nd the sttisticl model dopted considered the effects of THI nd pen. Dt of ech dy of oservtion were then grouped in three following time ggregtes ccording to the method proposed y Cozzi nd Gottrdo (25). The intervls rnged from the time of diet delivery to 8 h fter diet delivery (-8), from 9 to 16 h (9-16) nd from 17 to 24 h fter diet delivery (17-24). This dt set ws sumitted to sttisticl nlysis dopting model which considered the effects of THI nd pen, dytime intervl nd THI per dytime intervl interction. Results were considered sttisticlly significnt for P<.5. RESULTS AND DISCUSSION Dt in Tle 1, collected using the scn smpling technique nd relted to 24 hours of oservtions, showed tht lying, resting nd eting time were not ffected y the environmentl conditions, while hot climte significntly incresed time spent ruting. This significnt chnge in ehviour is not in greement with the expected results considering tht previous studies reported reduced rution under het stress conditions oth in diry cows (Collier et l., 1982; Tpkı nd Şhin, 26) nd ewes (Cost et l., 1992). In this reserch, the longer rution oserved could e due to n ttempt of cttle to control the reduction of rul ph likely due to the high strch content of the diet nd to diished slivry uffering cpcity consequent to n excessive urinry excretion of cron s shown y Collier et l. (1982). Tle 1. Lying, resting, eting nd ruting time nd drinking events performed y eef cttle under different THI conditions Type of ehviour Unit Temperture Humidity Index (THI) ove 78 - Hot 75-76 - Mild elow 72 - Cool RMSE Lying 798 791 816 48.21 Resting 235 265 258 54.9 Eting 16 114 117 17.71 Ruting 359 31 33 44.69 2

Drinking numer 14.33 11.8 9.75 4.7 Vlues with different superscript letters within row differ significntly (P<.5) Regrdless the THI conditions, eting ws highest during the first 8 hours following the diet delivery when fresh-mde feed ws ville (Figure 1) nd this is in greement with the result of previous study y Cozzi nd Gottrdo (25). Moreover, the interction Dytime intervl x THI showed, in the first 8 h fter feed delivery, t the highest THI, significnt reduction of time spent y the nimls eting (Figure 1) while incresed rution (Figure 1). Considering tht in the sme period, lying time (Figure 1) ws not ffected y different THI levels, it is likely tht rution ws performed in the stnding position s n ttempt of the ulls to dissipte ody het. 16 Eting 16 Ruting 14 14 12 12 1 8 6 1 8 6 4 4 2 2 36 32 Lying 8 Drinking 28 24 2 16 12 8 numer of events 6 4 2 4 Figure 1. Lest squre mens of the time () spent eting (RMSE = 1.72), ruting (RMSE = 21.79), lying (RMSE = 19.63) nd of the numer of drinking events (RMSE = 6.34) performed y eef cttle under different climtic conditions recorded in three time intervls from diet delivery (-8 h; 9-16 h nd 17-24 h) Under het stress condition, the greter wter demnd y the ulls ws the explntion for the significnt increse in the numer of visits t wterer (Tle 1). Moreover, when THI ws ove 78, the need to drink wter (Figure 1) ws prticulrly ccentuted during the first time intervl fter diet delivery (-8 h). Beef cttle drinking requirements re greter under therml stress conditions ecuse wter is consumed for het dissiption (vi pnting nd sweting) nd for cooling down the reticulorumen (Collier et l., 1982). Despite the lck of significnt sttisticl differences, there ws positive reltion etween the increse of THI nd the numer of mounts mong penmtes (Tle 2). This result, which ws previously oserved lso y Lewis (1985) in diry cows nd y Mitlöhner et l. (22) in grzing heifers could e the consequence of n incresed nervousness of the nimls. On the other hnd the similr numer of 3

fights recorded under different climtic conditions (Tle 2) supports the hypothesis tht therml discomfort did not increse ggressiveness in ulls. Tle 2. Numer of mounting nd fighting performed y eef cttle under different THI conditions Event Unit Temperture Humidity Index (THI) ove 78 - Hot 75-76 Mild elow 72 - Cool RMSE Mounts numer 7.75 5.17 3.58 7.71 Fights numer 26.83 25.33 28.67 12.56 CONCLUSION The effects of het stress re often seen s reduction of productive performnces ut niml welfre is noteworthy s well. Cttle ehviour is directly relted to its sttus of well-eing, therefore study of chnges in ehviours could e used to identify dredful environment. In prticulr, the results of the present study showed tht hot environment dversely ffected eting ehviour of the ulls while the higher rution ctivity represented n ttempt to cope with the pek of fermenttive ctivity in the rumen which follows the min mel of the niml right fter the provision of the fresh TMR. Therefore, ehviourl oservtion of eef cttle rered in indoors systems re useful tool to develop nd test cooling devices nd mngement strtegies to improve eef cttle welfre nd performnce during the hot seson. REFERENCES 1. Aeni, F., Minti, M.G., Clmri, L., Cpp, V., Stefnini, L. (1993): Effects of het stress on lctting diry cows nd feeding strtegy to reduce its impct on milk yield nd qulity. Annli dell Fcoltà di Agrri, Università Cttolic del Scro Cuore Milno, 33:151-17. 2. Armstrong, D.V. (1994): Het stress interction with shde nd cooling. Journl of Diry Science, 77:244-25. 3. Bernucci, U., Clmri, L. (1998): Effects of het stress on ovine milk yield nd composition. Zootecnic e Nutrizione Animle, 24:247-257. 4. Brown-Brndl, T.M., Eigenerg, R.A., Niener, J.A. (26): Het stress risk fctors of feedlot heifers. Livestock Science, 15:57-68. 5. Collier, R.J., Beede, D.K., Thtcher, W.W., Isrel, L.A., Wilcox, C.J. (1982): Influences of environment nd its modifiction on diry niml helth nd production. Journl of Diry Science, 65:2213-2227. 6. Cost, M.J.R.P., Silv, R.G., Souz, R.C. (1992): Effect of ir temperture nd humidity on ingestive ehviour of sheep. Interntionl Journl of Biometeorology, 36:218-222. 7. Cozzi, G., Gottrdo, F. (25): Feeding Behviour nd Diet Selection of Finishing Limousin Bulls Under Intensive Rering System. Applied Animl Behviour Science, 91:181-192. 8. Cozzi, G., Rgno, E. (23): Met production nd mrket in Itly. Agriculture conspectus scientificus, 68(2):71-77. 9. INRA - Institute Ntionl de l Recherche Agronomique. (1988): Alimenttion des ovines, ovins et crpins. INRA, Pris. 1. Lewis, I. (1985): Behviourl nd thermoregultory responses of Germn Blck Pied cows to het stress. In: Untersuchengen zum Verhlten und zur Thermoregultion unter dem Einfluss einer Wrmeelstung n Kuhen der Rsse Deutsche Schwrzunte. Fchereich Veterinrmedizin der Freien Universitt Berlin. (s.) 11. Mekw, M., Beuche, K.A., Christensen, D.A. (22): Chewing ctivity, sliv production, nd rul ph of primiprous nd multiprous lctting diry cows. Journl of Diry Science, 85:1176-1182. 12. Mrtin P., Bteson P. (1993): Mesuring ehviour, n introductory guide. Cmridge University press, Cmridge, UK. 4

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