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Temperate and tropical conditions impact on production and thermoregulatory traits in growing pigs
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Edité par CCSD ; Wageningen Academic Publishers -
The aim of the study was to evaluate the effects of two environment (temperate TEMP vs tropical humid TROP) on production trait and thermoregulatory response of genetically linked growing pigs. Large white (LW) pigs were crossed with tropical pigs from the Creole breed (CR), which is less productive but more thermotolerant than LW. A total of 1,296 half-sib backcross, from 10 (LW x CR) boars and about 65 LW sows in each environment were reared in TROP (n=667) and in TEMP (n=629). TROP was characterized by an average daily ambient temperature (T) of 26.0±0.3 °C and an a'erage daily relative humidity (RH) of 84.5±0.5%. The corresponding values for TEMP were 25.1±0.6 °C and 61.2±3.8% respectively. Live body weight (BW) was measured at the beginning of test (week 11), at weeks 19 and 21, and at the end of test (week 23). Backfat thickness (BT) and cutaneous temperature (CT) were measured at weeks 19 and 23. Rectal temperature (RT) was recorded at weeks 19, 21 and 23. Under TROP, the average daily gain (ADG) during the test and BT were lower than under TEMP (718 vs 813 g/d and 14 vs 18 mm, P<0.001). CT and RT declined from week 19 to week 23 (-0.5 and -0.2 °C, respectively, P<0.001), and they were higher at ali stages in TROP than in TEMP (35.9 vs 34.8 °C and 39.5 vs 39.4 °C, respectively, P<0.001). A moderate phenotypic correlation was obtained between CT and RT (rp=0.3). Correlations were low between ADG from week 19 to week 23 and thermoregulatory traits (rp=0.1 with CT and rp=-0.03 with RT). Furthermore, BW, ADG, RT and BT showed significant sire x environment interactions. Further research will focus on genetic approach to quantify the level of genetic by environment interactions.
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