Studies on the Metabolic Energy Saving Characteristics in Swamp Buffaloes.

点击翻译按钮获取中文摘要

Hearts and lungs were isolated from buffaloes, Holsteins and Brahman-Thai native crosses and was their anatomical characteristics compared. Even though the body weight was significantly heavier in Holsteins than in buffaloes or in Brahman-Thai native crosses, in terms of heart/body weight (%) and lung/body weight (%), buffaloes showed a significantly higher percentage than the Holsteins or the Brahman-Thai native crosses. No significant difference was found in the lung weight/heart weight ratio between buffaloes and Brahman-Thai native crosses, whereas the ratio was significantly lower in Holsteins than in either buffaloes or Brahman-Thai native crosses. The arch of the aorta could be anatomically characterized as being thick and large in buffaloes, thin but large in Holsteins and small in Brahman-Thai native crosses, respectively. Although the general shape of the heart was similar, muscular distribution in the heart was found to be considerably different among buffaloes, Holsteins an … More d Brahman-Thai native crosses. A constant balance in size between ventral and dosal papillary muscles was observed in spite of the difference in cardiac size.Intrinsic heart rate and autonomic nervous tone in swamp buffaloes were compared with those in cattle by the administration of autonomic blockers. Resting heart rate was significantly lower in buffaloes than in cattle (mean S. E. ; 49.5 1.2 vs 62.0 1.4 beats/min.). Furthermore, buffaloes showed a significantly lower intrinsic heart rate than cattle (56.2<plus-minus>1.8 vs 76.7<plus-minus>3.1 beats/min.). On the other hand, the net autonomic tone calculated from the changes in heart beats recorded before and after the administration of the blockers showed a parasympathetic-predominant type in both species, with the absolute value being smaller in buffaloes than in cattle (-9.0<plus-minus>7.3 vs -21.3<plus-minus>5.1%). On the basis of the results obtained, it is suggested that lower resting heart rate observed in buffaloes may be due to the lower intrinsic heart rate rather than to be inhibitoryeffect of the parasympathetic nervous Less