Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/27/2005
Publication Date: 5/27/2005
Citation: Powers, W.J., Bastyr, S.B., Kerr, B.J. 2005. Effect of reduced crude protein diets on gaseous emissions and swine performance. Proceedings of International Workshop on Green Pork Production. p. 61-62. Interpretive Summary:
Technical Abstract: Forty-eight crossbred barrows (initial body weight = 18 kg) were allocated to one of eight environmental rooms (six pigs per room) for 2-wk prior to diet implementation. Pigs were allowed ad libitum access to one of three pelleted isocaloric, isolycinic diets: a control diet (C), a low crude protein diet (LCP), and an ultra low crude protein diet (ULCP), each supplemented with varying amounts of crystalline amino acids. The C and LCP diets were offered in each of three of the eight rooms, and the ULCP diet was offered in the remaining two rooms. Formulated CP levels of the first grower diets were 22.5, 20.0, and 18.4% for the C, LCP, and ULCP diets, respectively. As feeding phases progressed there was a decrease in the formulated CP such that the fourth sequence of diets were formulated to contain 16.6, 15.4, and 13.8% CP in the C, LCP, and ULCP diets, respectively. Pigs weighs and feed intake were recorded weekly over the course of four feeding phases: grower-1, 25 to 55 kg; grower-2, 55 to 87 kg; finisher-1, 87 to 111 kg; and finisher-2, 111 to xxx kg. During each feeding phase, excreted manure was sub-sampled and weighed in order to provide an estimate of volume and nutrient content excreted from each treatment. Exhaust air from each room was sampled in a consecutive manner: 15 minutes of sampling from a room followed by 15 minutes of sampling from the next room. Background measures of the incoming air was sampled before each full round of room sampling, such that there were 10 to 11 daily observations from each room. Exhaust air was evaluated using TEI Model 17C (ammonia/NOx chemiluminescence) and TEI Model 45C (H2S/SOx pulsed fluorescence) analyzers. Dietary treatment had no effect on overall gain, feed intake or feed efficiency (P > 0.05). Airflow-corrected daily ammonia emissions were 26.8, 21.0, and 14.5 mg min-1, for the C, LCP, and ULCP diets, respectively. Hydrogen sulfide emissions were not affected by dietary treatment (P > 0.05). This was not expected as pigs fed the reduced CP, amino acid-supplemented diets would have had slightly lower total dietary sulfur content. Dietary treatment had no effect or wet- or dry-mass of manure produced. However, total manure nitrogen and ammonia nitrogen concentration decreased with decreasing dietary CP (7.9, 6.7, and 5.7% total nitrogen; 5.4, 4.4, and 3.5% ammonia nitrogen) for C, LCP, and ULCP diets, respectively. Findings from this study demonstrate that reduced crude protein diets can be fed throughout the growing-finishing phase with no detrimental effects on animal performance, but will substantially reduce ammonia emissions.