J Anim Sci. 2021 Mar 23:skab090. doi: 10.1093/jas/skab090. Online ahead of print.
ABSTRACT
Two experiments determined the effects of crude protein (CP) in diets containing coarse wheat bran (CWB) with or without pharmacological levels of Zn on weanling pig growth performance. In Exp. 1, treatments included a positive control (21% CP) with 3,000 mg/kg Zn in phase 1 and 2,000 mg/kg in phase 2; negative control (21% CP) with 110 mg/kg Zn, and four diets containing 4% CWB and 110 mg/kg Zn formulated to 21, 19.5, 18, or 16.5% CP. The three diets with 21% CP and CWB contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2, while the 19.5, 18, and 16.5% CP diets contained 1.35, 1.25 and 1.20% Lys, respectively. Pigs fed the diet containing pharmacological Zn had increased (P < 0.05) ADG and G:F compared to the negative control and the 21% CP CWB diet. Reducing CP decreased ADG and G:F (linear, P = 0.002). In Exp. 2, diets consisted of: 1) positive control with 2,000 mg/kg of Zn and 21% CP (1.35% SID Lys); 2) 110 mg/kg Zn and 21% CP; and 3 diets with 110 mg/kg Zn and 18% CP with 3) 1.2% SID Lys; 4) 1.35% SID Lys by the addition of crystalline AA, and 5) diet 4 with added non-essential AA. Pigs fed 21% CP with Zn had increased (P = 0.001) ADG compared to those fed 18% CP (1.35% SID Lys) or 1.2% SID Lys. In summary, added Zn improved growth performance, but reducing CP did not.
PMID:33755175 | DOI:10.1093/jas/skab090
