Roberts S B, Coward W A
Ann Nutr Metab. 1985;29(1):19-22. doi: 10.1159/000176949.
The oxygen consumption rates of virgin and lactating rats fed ad libitum were measured at temperatures ranging from 1 to 28 degrees C. The oxygen consumption rates of the virgin animals decreased progressively with increasing ambient temperature, but those of the lactating animals decreased slightly between 1 and 8 degrees C, remained approximately constant between 8 and 20 degrees C and fell rapidly above 20 degrees C. It is suggested that the fall in oxygen consumption rate above 20 degrees C in the lactating rats was due to a reduction in milk synthesis rate, and that the thermoneutral zone for normal lactation was 8-20 degrees C; this is a substantially cooler range than that of virgin rats (28-29 degrees C). The net energetic efficiency of milk production was calculated from the energy output in milk and the amount of energy used to produce milk (estimated from the oxygen consumption rates). The value obtained was 57.0%.
在1至28摄氏度的温度范围内，对自由采食的未生育大鼠和泌乳大鼠的耗氧率进行了测量。未生育动物的耗氧率随着环境温度的升高而逐渐降低，但泌乳动物的耗氧率在1至8摄氏度之间略有下降，在8至20摄氏度之间保持大致恒定，在20摄氏度以上则迅速下降。有人认为，泌乳大鼠在20摄氏度以上耗氧率下降是由于乳汁合成率降低，正常泌乳的热中性区为8至20摄氏度；这一温度范围比未生育大鼠的热中性区（28至29摄氏度）要低得多。根据乳汁中的能量输出和用于产奶的能量（根据耗氧率估算）计算出了产奶的净能量效率。得到的值为57.0%。
