Determination of Net Energy Content of Hemp Hulls and Processed Hemp Hull Products Fed to Growing Pigs Using Indirect Calorimetry

The production of hemp hulls (HH), a by-product of shelled hempseed, has gradually increased because of increased human consumption of shelled hempseed. Due to its high protein and oil contents, HH has potential as a protein and energy source for swine diets. However, the nutritive value of HH for swine has yet to be evaluated. Therefore, this study was conducted to determine the NE contents of HH, extruded HH (EHH), and a blended product of HH with pea (HHP) fed to growing pigs using indirect calorimetry (IC). Twenty four growing male pigs [(Yorkshire ×Landrace) × Duroc] with an average initial BW of 22.9 ± 1.75 kg were individually housed in adjustable metabolism crates. Pigs were randomly allotted to 1 of 4 dietary treatments to give 6 replicates per treatment. A corn-soybean meal (SBM) basal diet was prepared and three additional diets were formulated to contain a 70:30 ratio of the basal diet and each of test ingredients (HH, EHH, and HHP). Pigs were fed experimental diets for 16 d including 10 d for adaptation and 6 d for total collection of feces and urine to determine DE and ME contents. Pigs were then moved into indirect calorimetry chambers to determine heat production (HP) and fasting heat production (FHP) based on O₂ consumption, CO₂ production, and urinary N excretion. The DE, ME, and NE contents of the basal diet were greater (P < 0.01) than the HH, EHH, and HHP diets. No significant differences were observed for the HP (on average 1,904 kcal/kg DM) and FHP (on average 1,320 kcal/kg DM) among treatments. However, the retained energy of pigs fed the basal diet (1,763 kcal/kg DM) was greater (P < 0.05) than those fed the HH (1,501 kcal/kg DM) and HHP (1,482 kcal/kg DM) diets. The NE:ME ratio tended to be greater for the basal diet (0.85) than for the HH (0.82), EHH (0.82), and HHP (0.83) diets. The NE contents of HH, EHH, and HHP were determined to be 2,341, 2,315, and 2,407 kcal/kg DM, respectively. In conclusion, the HH, EHH, and HHP contains relatively high levels of NE contents due to its high oil content, and therefore can be a potential alternative energy source for swine.