Effect of reducing dietary crude protein level on growth performance, blood profiles, nutrient digestibility, carcass traits, and odor emissions in growing-finishing pigs

Abstract

Objective This study was conducted to evaluate the effect of a low-protein diet on growth performance, carcass traits, nutrient digestibility, blood profiles, and odor emissions in growing-finishing pigs. Methods A total of 126 crossbred pigs ([Yorkshire×Landrace]×Duroc) with an average body weight (BW) of 38.56±0.53 kg were used for a 14-week feeding trial. Experimental pigs were allotted to one of 6 treatments in 3 replicates of 7 pigs per pen in a randomized complete block design. Pigs were fed each treatment diet with different levels of crude protein (CP). Phase 1 (early growing): 14%, 15%, 16%, 17%, 18%, 19%; phase 2 (late growing): 13%, 14%, 15%, 16%, 17%, 18%; phase 3 (early finishing): 12%, 13%, 14%, 15%, 16%, 17%; phase 4 (late finishing): 11%, 12%, 13%, 14%, 15%, 16%. All experimental diets in each phase were contained the same concentration of lysine (Lys), methionine (Met), threonine (Thr), and tryptophan (Trp). Results Over the entire experimental period, there was no significant difference in BW, average daily feed intake, and gain-to-feed ratio among all treatments (p>0.05), but a quadratic effect (p = 0.04) was observed in average daily gain (ADG) during the late finishing phase with higher ADG in Group D. Blood urea nitrogen concentration linearly increased with an increase in dietary CP levels (p0.05). Conclusion In phase feeding, reducing the CP level to 14% in early-growing pigs, 13% in late-growing pigs, 12% in early-finishing pigs, and 11% in late-finishing pigs is recommended.

Keywords

• blood profiles
• growing-finishing pigs
• growth performance
• low-protein diet
• odor emissions