Ammonia emissions and dry matter of separated pig manure fractions as affected by crude protein concentration and sugar beet pulp inclusion of finishing pig diets

It was hypothesised that decreasing dietary crude protein (CP) and including sugar beet pulp (SBP) would reduce the urine:faeces nitrogen (N) excretion ratio of finisher boars and decrease ammonia emissions from separated liquid and solid manure fractions. A 2 × 2 factorial experiment was conducted to investigate the effect of dietary CP concentration (150 g kg−1 vs. 200 g kg−1) and SBP (0 g kg−1 vs. 200 g kg−1) inclusion on nutrient digestibility, N excretion and manure output from finisher boars (63 ± 1.3 kg). Urine and faeces collections were pooled in original excretion ratios. Manure samples were separated into liquid and solid fractions using separating-cloth. A 2 × 2 × 2 factorial design was used to investigate the interaction of CP concentration (150 g kg−1 vs. 200 g kg−1), SBP (0 g kg−1 vs. 200 g kg−1) and manure treatment (unseparated manure vs. cumulated separated fractions) on ammonia emissions from unseparated manure and cumulated fractions. There was an interaction between SBP and manure treatment (P < 0.01) on manure dry matter. Dietary SBP increased the dry matter of unseparated manure compared with pigs offered diets containing no SBP. However there was no effect of dietary SBP on dry matter of the separated fractions. Dietary SBP decreased ammonia emissions from 0 to 240 h (P < 0.05) from unseparated manure and separated fractions compared with unsupplemented diets. Decreasing dietary CP to 150 g kg−1 reduced total N excretion (P < 0.001) and ammonia emissions from 0 to 240 h (P < 0.1) from unseparated manure and separated fractions. There was an interaction between CP and SBP on N retention (P < 0.05). Pigs offered the 150 g kg−1 CP diet containing SBP decreased N retention compared with pigs offered the 150 g kg−1 CP diet containing no SBP. However there was no effect of SBP in pigs offered the high CP diets on N retention. Pigs offered diets containing SBP reduced manure volume (P < 0.05) compared with pigs offered diets containing no SBP. In conclusion, increasing dietary SBP and reducing CP concentrations decreased ammonia emissions from unseparated manure and separated liquid and solid fractions. Furthermore, dietary SBP increased the dry matter of unseparated manure however SBP inclusion had no effect on the dry matter of the separated manure fractions.