Nitrogen Excretion and Ammonia Emissions from Pigs Fed Modified Diets

Abstract

<p>Two swine feeding trials were conducted (initial body weight = 47 ± 2 and 41 ± 3 kg for Trials 1 and 2, respectively) to evaluate reduced crude protein (CP) and yucca (<em>Yucca schidigera</em> Roezl ex Ortgies) extract–supplemented diets on NH₃ emissions. In Trial 1, nine pigs were offered a corn–soybean meal diet (C, 174 g kg⁻¹ CP), a Lys-supplemented diet (L, 170 g kg⁻¹ CP), or a 145 g kg⁻¹ CP diet supplemented with Lys, Met, Thr, and Trp (LMTT). In Trial 2, nine pigs were fed diet L supplemented with 0, 62.5, or 125 mg of yucca extract per kg diet. Each feeding period consisted of a 4-d dietary adjustment followed by 72 h of continuous NH₃ measurement. Urine and fecal samples were collected each period. Feeding the LMTT diet reduced (<em>P</em> < 0.05) average daily gain (ADG) and feed efficiency (G:F) compared to diet L. Fecal N concentration decreased with a reduction in dietary CP, but urinary ammonium increased from pigs fed diet LMTT (2.0 g kg⁻¹, wet basis) compared to those fed diet C (1.1 g kg⁻¹) or L (1.0 g kg⁻¹). When pigs were fed reduced CP diets NH₃emission rates decreased (2.46, 2.16, and 1.05 mg min⁻¹ for diets C, L, and LMTT). Yucca had no effect on feed intake, ADG, or G:F. Ammonium and N concentrations of manure and NH₃ emission rates did not differ with yucca content. Caution must be executed to maintain animal performance when strategies are implemented to reduce NH₃ emissions.</p>