Heat production in growing pigs calculated according to the RQ and CN methods

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Abstract

  • 1.

    1. Heat production, calculated according to the respiratory quotient methods, HE(RQ), and the carbon nitrogen balance method, HE(CN), was compared using the results from a total of 326 balance trials with 56 castrated male pigs fed different dietary composition and variable feed levels during the live wt range 20–120 kg.

  • 2.

    2. HE(RQ) was generally higher than HE(CN).

  • 3.

    3. HE(RQ) depended on feed composition and feed level and, consequently, on the synthesis and deposition of depot fat. For RQ-values above 1, HE(RQ) was overestimated.

  • 4.

    4. HE(CN) was generally underestimated, because N- and C-balances in general were overestimated due to losses in excreta.

  • 5.

    5. The difference between HE(RQ) and HE(CN) was not constant. It was smallest when fat synthesis and fat deposition were low (2–3.5%) and greatest when fat synthesis and fat deposition were high (7–9%). The presence of dietary fatty acids may affect the difference.

  • 6.

    6. In pigs receiving a cereal based diet, HE(RQ) may be expected to give 3–4% higher values than HE(CN), but in case easily available carbohydrates (glucose, sucrose) or high-fibre diets are provided, the differences may be larger.

  • 7.

    7. Both methods were carried out with similar accuracy and precision. The results indicated that both methods are equally reliable.

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