Potential for reduction of odorous compounds in swine manure through diet modification.

Abstract

Recent public concern about air pollution from pork production units has prompted more research to develop methods to reduce and control odors. Masking agents, enzymes and bacterial preparations, feed additives, chemicals, oxidation processes, air scrubbers, biofilters, and new ventilation systems have been studied. Research relating the effects of the swine diet on manure odors has been scarce. Introducing feed additives to bind ammonia, change digesta pH, affect specific enzyme activity, and mask odors has been either costly or not consistently successful. Recent research emphasis has focused on manipulating the diet 1) to increase the nutrient utilization of the diet to reduce excretion products, 2) to enhance microbial metabolism in the lower digestive tract to reduce excretion of odor-causing compounds, and 3) to change the physical characteristics of urine and feces to reduce odor emissions. Primary odor-causing compounds evolve from excess degradable proteins and lack of specific fermentable carbohydrates during microbial fermentation. Reductions in ammonia emissions by 28 to 79% through diet modifications have been reported. Limited research on reduction of other odorous volatile organic compounds through diet modifications is promising. Use of synthetic amino acids with reduced intact protein levels in diets significantly reduces nitrogen excretions and odor production. Addition of nonstarch polysaccharides and specific oligosaccharides further alters the pathway of nitrogen excretion and reduces odor emission. Continued nutritional and microbial research to incorporate protein degradation products, especially sulfur-containing organics, with fermentable carbohydrates in the lower gastrointestinal tract of pigs will further control odors from manure.

Effects of dietary crude protein level on odour from pig manure

“…It is generally accepted that dietary alterations can significantly reduce odour from pig manure (Le et al, 2005b). Dietary protein is one of the most important precursors for odour production thus it is expected that odour produced from pig manure will be Dietary protein level and odour from pig manure reduced as dietary CP level decreases (Mackie et al, 1998;Sutton et al, 1999). In this study, when dietary CP was reduced from 18% to 12% odour concentration and emission decreased by nearly 80%, or from 4.46 to 1.03 ou E /s per m 2 of the manure pit.…”

Effect of crude protein concentration and sugar-beet pulp on nutrient digestibility, nitrogen excretion, intestinal fermentation and manure ammonia and odour emissions from finisher pigs

“…The proportion of VFAs produced from hindgut fermentation depends on the composition of anaerobic flora, available substrate and gut pH (Le et al, 2005). Acetic acid, propionic acid and butyric acid are formed both from carbohydrates (Rasmussen et al, 1988;Sutton et al, 1999). However, isovaleric acid and isobutyric acid are produced exclusively from the deamination and decarboxylation of leucine and valine, respectively (Mackie et al, 1998), and contribute to malodour (Mackie et al, 1998).…”

Zeolites versus Lead Toxicity

“…Clinoptilolites are often utilized to draw heavy metals from solutions [4][5][6] and to purify deleterious emissions [7]. Diets manipulated by zeolites have the potentiality to reduce both the excess of N and P in swine manure, and to minimize the negative effects of odor and other gaseous emissions such as NH 3 and H 2 S from the swine waste [8,9]. As a feed additive, clinoptilolites have been used so far in poultry and livestock in order to positively influence feces consistency, reduce diarrhea, bound mycotoxins and aflatoxins, allow better performance of intestinal microflora [10].…”