Influence of heat stress, age, breed, productive status and breeding method on body measurements, body temperature and metabolic adaptation of sheep

[A. S. Čukić]

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Ekonomska održivost sistema proizvodnje ovaca širom sveta ugrožena je zbog razornih efekata klimatskih promena. Među višestrukim klimatskim stresovima sa kojima se suočavaju ovce, izgleda da toplotni stres (TS) u velikoj meri destabilizuje efikasnost proizvodnje ovaca. TS ugrožava rast, proizvodnju vune, mesa i mleka kod ovaca. Istraživanje je sprovedeno sa ciljem utvrđivanja uticaja TS na telesne mere, telesnu temperaturu merenu rektalno (RT) ili infracrvenom termografijom (IRT) nosa, oka, nogu i abdomena kao i na metaboličku adaptaciju kod ovaca različite starosti, rase, produktivnog statusa i načina uzgoja, kao i da se otkrije korelacija između telesne temperature i metaboličkog odgovora kod ovaca. Ispitivane su ukupno 33 ovce rase Il de Frans i meleza Virtemberg h Sjenička pramenka, od čega 17 iz otvorenog i 16 iz zatvorenog sistema uzgoja tokom tri eksperimentalna perioda (termoneutralni period, teški TS i umereni TS). Toplotni stres je uticao na većinu ispitivanih parametara. Starost i rasa su uticali na telesne mere ovaca, dok na ostale parametre ovi faktori nisu imali uticaj, osim rase na vrednosti holesterola (koje su veće kod Il de Frans), i kortizola (koje su veće kod meleza). Gravidnost je uticala na vrednosti širine karlice i temperaturu očiju i prednjih nogu, dok je laktacija uticala na temperaturu abdomena i prednjih nogu, T4, neesterifikovane masne kiseline (NEFA), ukupne proteine i GGT. Na ostale parametre gravidnost i laktacija nisu imali uticaj. Način uzgoja je uticao na većinu mera telesne razvijenosti ovaca kao i na telesnu temperaturu i određene metaboličke parametre. Ovce pod TS su imale veću telesnu temperaturu, a temperatura merena IRT bila je veća od RT. Temperature prednje noge (NT) i abdomena (AT) su pokazale pozitivnu linearnu korelaciju sa indeksom temperature i vlažnosti (THI), dok drugi načini merenja temperature nisu dali statistički značajne korelacije. Ovce pod TS su imale više kortizola, insulina, ukupnih proteina, albumina, uree, kreatinina, bilirubina, aspartat aminotransferaze, alanin aminotransferaze, gama-glutamil transferaze, alkalne fosfataze, laktat dehidrogenaze, kreatin kinaze i indeksa insulinske rezistencije, a niže vrednosti trijodtironina (T3), tiroksina (T4), NEFA, beta-hidroksibutirata (BHB), glukoze, kalcijuma, neorganskog fosfora, magnezijuma i svih holesterola. Telesna temperatura i metabolički odgovor bili su različiti u funkciji načina uzgoja ovaca. NT i AT su pokazale značajnu korelaciju sa skoro svim krvnim parametrima, a najjače veze ostvarene su sa T3, T4, BHB i revidiranim kvantitativnim indeksom insulinske osetljivosti za proveru insulinske rezistencije. Abdomen i noge su dobri termalni prozori jer su NT i AT dobri sumativni odgovori na spoljašnji ambijentalni THI i unutrašnje metaboličke promene kod ovaca pod toplotnim stresom.

Economic viability of sheep production systems around the world is threatened by the devastating effects of climate change. Among the multiple climatic stresses faced by sheep, heat stress (HS) appears to greatly destabilize sheep production efficiency. HS threatens the growth, production of wool, meat and milk in sheep. This research was conducted with the aim of determining the effect of HS on body measurements, body temperature measured rectally (RT) or infrared thermography (IRT) of the nose, eye, legs and abdomen, as well as on metabolic adaptation in sheep of different ages, breeds, productive status and breeding methods and to reveal the correlation between body temperature and metabolic response in sheep. A total of 33 sheep of the Ile de France breed and crossbred Württemberg x Sjenicka pramenka were examined, of which 17 ewes were from outdoors and 16 were from indoorhousing systems during three experimental periods (thermoneutral period, severe HS and moderate HS).Heat stress affects most of the examined parameters. Age and breed affect the body measurements of sheep, while these factors had no effect on the other parameters, except for the breed on cholesterol values, which were higher in Ile de France, and cortisol, which were higher in crossbreeds. Pregnancy affects the values of pelvic width and the temperature of the eyes and front leg, while lactation on the temperature of the abdomen and front leg, T4, non-esterified fatty acid (NEFA), total proteins and GGT, pregnancy and lactation had no effect on the other parameters. Breeding method affects most body measurements of sheep, as well as body temperature and certain metabolic parameters. Sheep under HS have a higher body temperature, and the temperature measured by IRT was higher than RT. Front leg (LT) and abdomen (AT) showed a positive linear correlation with the temperature and humidity index (THI), while other methods of temperature measurement did not show statistically significant correlations.Sheep under HS showed higher cortisol, insulin, total protein, albumin, urea, creatinine, bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, lactate dehydrogenase, creatine kinase and insulin resistance index, with lower values of triiodothyronine (T3), thyroxine (T4), NEFA, beta-hydroxybutyrate (BHB), glucose, calcium, inorganic phosphorus, magnesium and all cholesterol. Body temperature and metabolic response were different in the function of breeding method of sheep. LT and AT showed a significant correlation with almost all blood parameters, and the strongest connections were made with T3, T4, BHB and the revised quantitative insulin sensitivity check index of insulin resistance. The abdomen and legs are good thermal windows because LT and AT are good summative responses to external ambient THI and internal metabolic changes in sheep under heat stress.

ovce, toplotni stres, THI, termoregulacija, adaptacija

sheep, heat stress, THI, thermoregulation, adaptation

636.333/.34:591.128(043.3)

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