Feed is single most expensive input in commercial pork production representing more than 50% of the total cost of production. The greatest proportion of this cost is associated with the energy component, thus making energy the most important dietary in terms of cost. For efficient pork production, it is imperative that diets are formulated to accurately match dietary energy supply to requirements for maintenance and productive functions. To achieve this goal, it is critical that the energy value of feeds is precisely determined and that the energy system that best meets the energy needs of a pig is used. Therefore, the present review focuses on dietary supply and needs for pigs and the available energy systems for formulating swine diets with particular emphasis on the net energy system. In addition to providing a more accurate estimate of the energy available to the animal in an ingredient and the subsequent diet, diets formulated using the this system are typically lower in crude protein, which leads to additional benefits in terms of reduced nitrogen excretion and consequent environmental pollution. Furthermore, using the net energy system may reduce diet cost as it allows for increased use of feedstuffs containing fibre in place of feedstuffs containing starch. A brief review of the use of distiller dried grains with solubles in swine diets as an energy source is included.

The aim of this study was to assess the effects of increasing levels of expeller extracted canola meal (EECM) in diets for growing pigs on performance, gastrointestinal tract weight, thyroid gland weights, blood plasma concentration of triiodothyronine and tetraiodothyronine, red blood cell count, hemoglobin content in blood, and hematocrit. Four diets were fed to 48 pigs (19.9 ± 1.60 kg initial BW) in 24 pens (6 pens per diet) for 4 wk in a completely randomized design. The diets were a control corn-soybean meal basal diet and 3 additional diets produced by replacing 33, 66, or 100% of soybean meal with EECM to achieve inclusion levels of 0, 10, 20, and 30%. Diets were formulated to be similar in NE and nutrient composition and to meet nutrient requirements for pigs. Pigs were allowed ad libitum access to feed and water for the duration of the study. Feed intake and BW of pigs were determined on a weekly basis, whereas organ weights and blood parameters were determined at the end of the study. Average daily feed intake linearly decreased ( = 0.001) whereas ADG tended to linearly decline ( = 0.084) with increasing levels of EECM in the diet. The G:F was not affected ( > 0.10) by the dietary level of EECM. Thyroid weight and serum triiodothyronine linearly increased ( = 0.031) whereas serum tetraiodothyronine was linearly reduced ( = 0.001) with increasing inclusion of EECM. Other blood parameters and organ weights were not affected by increasing inclusion of EECM. The analyzed concentration of glucosinolates in the EECM used in this study was 9.27 μmol/g, with values in the diets ranging from 1.02 to 2.75 μmol/g for the lowest to highest inclusion levels, respectively. The increased thyroid weight and changes in thyroid hormones indicate that glucosinolates present in EECM adversely affected performance of growing pigs.

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Two experiments were conducted to determine the NE content of dry extruded-expelled soybean (DESBM) and the effect of a multienzyme carbohydrase (MC) mixture on the NE content of DESBM and to determine the effect of diet design on NE values in growing pigs using indirect calorimetry (IC). In Exp. 1, 24 barrows (19.6 ± 0.51 kg BW) were allotted in a completely randomized design to 4 dietary treatments: a corn–soybean meal basal diet (Diet A), a diet containing Diet A and DESBM in an 80:20 ratio with a constant CP (Diet B), a diet with an 80:20 ratio of Diet A and DESBM with a constant corn:soybean meal ratio (Diet C), and a diet with simple substitution of Diet A with DESBM in an 80:20 ratio (Diet D). Pigs were fed in metabolism crates for a period of 16 d to determine the DE and ME and thereafter were moved into an indirect calorimeter where O2 consumption and CO2 production were measured to determine heat production and fasting heat production. The NE content of DESBM was calculated (difference method) to be 2,632, 2,548 and 2,540 kcal/kg DM in diets B, C, and D, respectively. Respective values obtained with published prediction equations were 2,624, 2,530 and 2,436 kcal/kg. In Exp. 2, 24 barrows (16.9 ± 0.76 kg BW) were randomly allotted to 1 of 4 treatments. The diets were a corn–soybean meal basal diet and a diet containing the basal diet and DESBM in an 80:20 ratio with a constant corn:soybean meal ratio with or without 2 levels (0.05% and 0.1%) of MC. The experimental procedures were similar to those described in Exp. 1. Enzyme supplementation improved (P < 0.0001) the DE, ME, and NE content of the DESBM. Multienzyme carbohydrase at 0.05% and 0.1% of the diet improved NE values of DESBM by 4.9% and 3.7%, respectively. In conclusion, the NE values of DESBM obtained with the IC method were higher than the values obtained with prediction equations; the disparity was least when diets were formulated with a constant CP level. However, as the difference method was used to determine the NE of ingredient, it is more appropriate to maintain a constant ratio between the ingredients. Also, the NE value of DESBM obtained for diets C and D were not different. Hence, the average NE value of DESBM evaluated was 2,544 kcal/kg DM. Enzyme supplementation improved the NE content of DESBM fed to growing pigs.

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