Influence of low-protein diets and protease and bromelain supplementation on growth performance, nutrient digestibility, blood urine nitrogen, creatinine, and faecal noxious gas in growing–finishing pigs

A total of 180 crossbred pigs [(Landrace × Yorkshire) × Duroc] with an average body weight of 22.61 ± 1.23 kg were used in an 18 wk study to determine the effect of protease and bromelain in low-protein diets in grower–finisher pigs. Dietary treatments included: T1, basal diet treatment; T2, low-protein treatment; T3 (T2 + 0.2 g kg⁻¹ protease); and T4 (T2 + 0.3 g kg⁻¹ bromelain). Pigs fed protease-and bromelain-supplemented diets increased average daily gain and gain to feed ratio at week 18, dry matter and nitrogen digestibility at week 6, as well as energy digestibility at week 12, compared with low-protein diet (P < 0.05). Pigs fed T3 and T4 diets led to a trend of decreased (P < 0.05) blood urine nitrogen (BUN) and creatinine concentrations at the 12th wk. A reduction of ammonia (NH₃) and hydrogen sulfide (H₂ S) emission was observed in pigs fed the dietary protease and bromelain supplementation at the 6th wk (P < 0.05). There was no effect on all parameters between the protease and bromelain supplementation treatments. In conclusion, supplementation of protease and bromelain to low-protein diet enhanced growth performance, nutrient digestibility, and reduced NH₃ and H₂ S in growing–finishing pigs.