Estimation of energy and protein requirements for Korean native heifers. 1. Estimation of energy and protein requirements for Korean native heifers by metabolism trial

Chung, Y.H.; Lee, S.C.; Kang, S.W.; Chung, C.S.; Chung, C.Y.

Korean Journal of Animal Sciences 34(5): 293-300


Accession: 002373188

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Native Korean heifers were fed on diets containing rice straw and concentrates to achieve target daily gains of 0.2, 0.6 and 0.8 kg (T1, T2 and T3, respectively) at 150-200, 200-250, 250-300 and 350 kg body weight. Average daily gain (DG) was 0.30 (T1), 0.62 (T2) and 0.67 kg (T3), respectively. Except for crude fibre, digestibilities and nutritive values of the diet were increased with increasing DG. Nitrogen intake was increased (P<0.05) with increasing DG, but there were no differences in digestible N intake and N retention between T2 and T3. Based on pooled data of body weight classes, nitrogen and digestible nitrogen (DN) requirements were estimated as follows: N requirement (g/kg0.75 daily) = 0.98 + 1.25 DG - 0.44 DGsuperscript 2 (Rsuperscript 2=0.42), DN requirement (g/kg0.75 daily) = 0.40 + 1.19 DG - 0.24 DGsuperscript 2 (Rsuperscript 2=0.49). Metabolizable energy (ME) intake, heat production and energy retention increased with increasing DG not with body weight, although there was no difference between T2 and T3. Energy losses expressed as a percent of gross energy (GE) intake was highest from faeces (42.8%), followed by heat production (42.3%), and lowest from urine (2.0%). Total digestible nutrient (TDN), digestible energy (DE) and ME requirements were as follows: TDN requirement (g/kg0.75 daily) = 28.13 + 60.40 DG - 14.03 DGsuperscript 2 (Rsuperscript 2=0.48), DE requirement (kcal/kgo.75 daily) = 134.34 + 220.59 DG - 71.90 DGsuperscript 2 (Rsuperscript 2=0.54), ME requirement (kcal/kg0.75 daily) = 116.98 + 171.32 DG - 35.73 DGsuperscript 2 (Rsuperscript 2=0.54). TDN, DE and ME requirements for maintenance were 28.13 kg, 134.3 kcal and 116.98 kcal/kg0.75 daily, respectively. Estimated net energy for maintenance requirement from the relation between ME intake and heat production was 76.5 kcal/kg0.75 daily.