Estimation of Heat Production from Heart Rate Measurements in Lactating Dairy Cows

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  • 泌乳牛の心拍数と熱発生量の関係について
  • ヒニュウギュウ ノ シンパクスウ ト ネツ ハッセイリョウ ノ カンケイ ニ

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Heart rate (HR) and heat production (HP) of six lactating Holstein cows were measuered simultaneously using mask method, and also mean HRs during 24 hours were measured for eleven lactating dairy cows under the feeding experiments. 1) A close relationship between HR and HP was obtained in each one of six cows. The prediction errors (PE) which were expressed as a percentage of the mean level of y for the standard deviation of y (Sy•x) were within the range of ±4.7 to ±9.1% for all of the animals. It is suggested that the HR measurements could offer a practical method of measuring HP of lactating dairy cows on free range. However, the individual differences on the regression constants still persist as shown in Table 1. 2) Eliminating the calibration of regression on each animal, the two equations which estimate HP from HR measurements on lactating dairy cows would be suggested as follows, (1) Y=-0.401+0.113X (Sb=±0.0059∗∗, r=0.89∗∗, PE=±6.900) Y: HP Kcal/W0.75. h, X: HR beats/min, (2) Y=-0.347+6.93X (Sb=±0.366∗∗, r=0.89∗∗, PE=±7.0%, ∗∗P<0.01) Y: HP Kcal/W0.75. h, X: RHR (relative HR, RHR 1=61.3 beats/min). The better way to estimate HP from HR measurements would be to use the mean HR from 4 to 6 animals at least in order to remove the individual differences of HR. 3) The clear difference on estimated HP was observed between lactating cows and the pooled dairy bull calves and steers, but the significant difference on the regression coefficient was not observed between them. The ratio of RHR to RHP (relative HP) was nearly 1:1 in lactating dairy cows and the pooled dairy bull calves and steers.

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