The breath-test for sheep: a possible means of identifying lean genotypes

S.W. Peterson

Animal Science Department, Massey University, Palmerston North

Proceedings of the New Zealand Society of Animal Production. 1984, 44: 205-208

Calorimetry apparatus was used to measure CO2 production and oxygen consumption in 2 Romney and 2 Southdown ewes. Each pair consisted of a long-lean ewe and a short-fat ewe as determined from previous records of height, length, weight and ultrasonic back fat thickness. The respiratory exchange ratio (RER) was calculated as the ratio of CO2 produced/d to O2 consumed/d. When the 4 ewes were fed, the RER remained about 1, characteristic of the oxidation of glucose and short chain fatty acids. When the ewes were fasted for 4 to 5 days the RER declined in a straight linear fashion with time. This is consistent with the mobilisation of long chain fatty acids. The ewes of fatter genotypes exhibited significantly steeper regressions of RER on time.

Keywords: NZSAPAB; Sheep; fat; lean; fasted; calorimetry; respiratory exchange ratio

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