Some physiological and behavioural responses inBos indicus andBos taurus heifers acclimatized to the hot humid seasonal equatorial climate

Some physiological and behavioural responses were observed in German Brown, Holstein-Friesian and White Fulani heifers during four different quarters of the year in an attempt to assess their adaptability to the seasonal equatorial climate of Southern Nigeria. Rectal temperatures under shade conditions showed slight but significant (P<0.05) fluctuations. Holstein heifers experienced hyperthermia and panted in the sun, unlike the Brown and Fulani cattle. Breathing rate showed a highly significant (P<0.01) seasonal variation. The heifers were generally most comfortable during the wettest periods of the year. The Holstein and Fulani showed the highest and lowest responses respectively. The Fulani did not seek shade; the Holstein sought shade more frequently than the Brown heifers. The Brown are more adaptable than the Holstein to the hot humid environment in which the Fulani cattle are relatively comfortable.