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Animal Science

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Journal of Animal Science





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The net energy (NE) system describes the useful energy available for growth better than the metabolizable energy (ME) system. The use of NE in diet formulation should maintain growth performance and carcass parameters when diets contain a diversity of ingredients. This study compared the growth performance of pigs on diets formulated using either the ME or NE system. A total of 944 gilts and 1,110 castrates (initial BW = 40.8 ± 2.0 kg) were allotted to group pens and assigned to one of 5 different feeding programs according to a randomized complete block design. A simple corn-soybean meal control (CTL) established baseline levels of ME or NE concentrations for the other dietary treatments. Thus, for two of the treatments, corn DDGS were added at 25% and formulated to achieve a constant ME or constant NE relative to the CTL (ME-D and NE-D). For the other two treatments, corn DDGS and corn germ meal were added at 15% and 20%, respectively, formulated to achieve a constant ME or a constant NE diet (ME-DC and NE-DC). When required, fat was added as an energy source. Pigs were harvested at an average BW of 130.3 ± 4.0 kg. Growth performance was not affected by treatment (P = 0.581, P = 0. 177 and P = 0.187 for ADG, ADFI and G: F ratio respectively). However, carcass growth decreased with the addition of co-products except for the NE-D treatment (P=0.016, P = 0.001, P = 0.018, P = 0.010 and P = 0.010 for dressing percentage, HCW, carcass ADG, back fat and loin depth respectively). Carcass G:F and lean percentage did not differ among treatments (P = 0.109 and P = 0.433). On the other hand, NE intake decreased (P = 0.035) similarly to that of carcass gain, suggesting a relationship between NE intake and energy retention. Calculations of NE per kg of BW gain differed among treatments (P = 0.010), but NE per kg of carcass was similar among treatments (P = 0.640) This suggests that NE may be better than ME at explaining the carcass results. Finally, ME intake and ME per kg of BW gain were not different among treatments (P = 0.112), but ME per kg of carcass gain was different among treatments (P = 0.048). In conclusion, the sequential addition of co-products in diets formulated on an NE or ME basis can result in similar growth performance, but carcass parameters may be affected independently of the energy system used. However, formulating diets based on NE tended to improve predictability of growth, especially carcass parameters.


This is a manuscript of an article published as Acosta, J., J. F. Patience, and R. D. Boyd. "Comparison of growth and efficiency of dietary energy utilization by growing pigs offered feeding programs based on the metabolizable energy or the net energy system." Journal of animal science 94, no. 4 (2016): 1520-1530. doi:10.2527/jas.2015-9321. Posted with permission.

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American Society of Animal Science



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