Study On Ammonia Emission And Model Of Growing-Finishing Pigs

Excessive ammonia emission not only results in loss of nitrogen in feed, but also brings pressure toenvironment. Pig production is a major source of ammonia emission. Most of research on ammoniaemission from pig housing was conducted in other countries. But pig breeding, feed composition andmanagement in China were different from those in other countries. There is little research on the relatedenvironmental effects in our country. The objective of the paper is to study the effects of various factorson ammonia emission and develop a model for predicting ammonia emission from growing-finishingaccording to actual production in our country, and to provide basic data of ammonia emission for pigproduction in China, The data and model could be benefit to develop environmental policy andabatement techniques.Twelve growing-finishing pigs of 20, 40, 60 and 80kg body weight (BW) were allotted to 4 diets.The animals were individually placed in metabolic cages in an environmentally controlled room. Fecesand urine were collected and weighed three times daily. According to orthogonal test design, the effectof temperature, dietary crude protein levels and BW on nitrogen excretion was examined, then the effectof temperature, ventilation flux, manure nitrogen content and depth on ammonia emission of feces andurine. Based on experimental data, ammonia emission model was developed. Finally, the model wasvalidated with an independent data set to determine its accuracy.Results are showed as followed:Daily fecal nitrogen excretion for pigs of 20, 40, 60 and 80kg BW were 3.62, 4.55, 7.72 and7.06g/d respectively, and daily urinary nitrogen excretion were 4.84,6.84,17.54 and 13.95g/drespectively under different treatments. Fecal nitrogen, urinary nitrogen and total nitrogen excretionwere 12.77%, 23.95% and 36.72% of nitrogen intake respectively. Temperature, dietary crude proteinlevels and BW had significant effect on fecal nitrogen, urinary nitrogen and total nitrogenexcretion(P＜0.01). Fecal nitrogen, urinary nitrogen and total nitrogen excretion increased withtemperature decreased and crude protein in diet increases. Fecal nitrogen excretion effect factors wereas follows: BW＞dietary crude protein levels＞temperature; urinary nitrogen effect factors were asfollows: temperature＞BW＞dietary crude protein levels; total nitrogen effect factors were as follows:temperature＞dietary crude protein levels＞BW. Different levels of temperature, crude protein levels andBW had significant influence on nitrogen excretion(P＜0.05).Temperature, ventilation flux, fecal nitrogen content and fecal depth had significant effects onammonia emissions of feces(P＜0.01); temperature, ventilation flux and urinary depth have significanteffects on ammonia emissions of urine(P＜0.01). Ammonia emissions of feces and urine increased withthe increase of temperature, ventilation flux, fecal nitrogen and urinary nitrogen content. Ammoniaemissions of feces effect factors were as follows: feces depth＞temperature＞fecal nitrogen content＞ventilation flux; ammonia emissions of urine effect factors were as follows: urinarydepth＞temperature＞ventilation flux＞urinary nitrogen content. Different levels of temperature, ventilation flux, nitrogen content of manure and manure depth had significant influence on ammoniaemission(P＜0.05).At the same time, model of fecal nitrogen and urinary nitrogen excretion were developed andexpressed respectively by FNE=-2.75-0.17T+0.31[NF]+0.07BW andUNE=-14.87-0.50T+0.95[Nu]+0.20BW; model of ammonia emission was expressed byENH3=-21.1-0.95T+0.83[NF]+0.39BW+(7.14+2.39T+5.4V-0.74DU)×WU+(-20.7+0.5T+5.15V-0.88DF)×WFValidated results showed that difference between modeling value and measuring value of fecalnitrogen and urinary nitrogen excretion was 5.45% and 17.05% respectively, and difference betweenmodeling value and measuring value of ammonia emission of feces and urine was 9.84% and 29.21%respectively.