Dietary composition affects odour emissions from meat chickens

Abatement of odour emissions has become an important consideration to agricultural industries,including poultry production. The link between diet and odour emissions was studied in two experiments using Ross 308 male meat chickens reared in specially designed chambers in a climate controlled room. In the first experiment, two treatments were compared using three replicates of two birds per chamber. Two wheat-soy based treatment diets were formulated with or without canola seed, an ingredient rich in sulfur amino acids, Treatment 1(T1) had 13,39 MJ/kg ME(as fed) and used 60 g/kg canola seed without corn while Treatment 2(T2) contained 12.90 MJ/kg ME(as fed) and used 150 g/kg corn without canola seed. In the second experiment, birds were assigned to three dietary treatments of five replicates with five birds per replicate(chamber). The basal starter, grower and finisher diets in the control group(SBM group) contained soybean meal in the range of 227-291 g/kg(as fed) as the main protein source. The other treatments(CM and MBM groups) contained either high levels of canola meal(174-190 g/kg) or meat meal(74-110 g/kg) at the expense of soybean meal. In both experiments, diets were isocaloric, isonitrogenous and contained similar digestible amino acid contents as per 2007 Aviagen Ross 308 guidelines. Emissions of odour were measured using Fourier transform infrared(FTIR) spectroscopy. In both experiments, major odorous compounds detected included 2,3-butanedione(diacetyl),2-butanone, dimethyl disulfide, methyl mercaptan, ethyl mercaptan, 2-butanol, 3-methyl-butanal,phenol and m-cresol. In the first experiment, Tl(with canola seed) produced higher concentration of methyl mercaptan(P < 0.05) and lower diacetyl(P < 0.01) than T2. In the second experiment, methyl mercaptan emission was higher in SBM group(P = 0.01) and total elemental sulfur were higher in SBM and CM groups up to day 24(P < 0.01). Results of these experiments indicated a direct link between diet and odour emissions from meat chickens.

Performance,litter quality and gaseous odour emissions of broilers fed phytase supplemented diets

The effect of graded levels of phytase on performance, bone characteristics, excreta/litter quality and odorant emissions was examined using 720 Ross 308 male d-old broilers. A 2 x 4 factorial arrangement of treatments was employed with 6 replicates of 15 birds per pen. Factors were: diets-positive and negative control(PC, NC); phytase-0, 500,1,000.1,500 FTU/kg. The PC was formulated to meet the 2014 Ross 308 nutrient specifications, whereas the NC was formulated with lower Ca(-1.4 g/kg), available P(-1.5 g/kg), Na(-0.3 g/kg), dLys(-0.2 g/kg) and MEn(-0.28 MJ/kg) equivalent to nutrient matrix values for 500 FTU/kg phytase in the starter,grower and finisher periods(i.e.,downspec diet). On d 24, phytase decreased FCR by 1.6, 4.3 and 4.6 points at inclusion levels of 500.1,000 and 1,500 FTU/kg, respectively(P < 0.01) across all diets. Phytase by diet interactions on BW gain were observed on d 24 and 35(P < 0.01). The effect of phytase was much more pronounced in the NC diet as compared with the PC diet.On d 24, phytase increased BW gain by 37, 55 and 68 g in the PC and 127.233 and 173 g in the NC at 500,1,000 and 1,500 FTU/kg, respectively. Diet by phytase interactions were also observed for tibia ash, litter quality and water to feed intake ratio(P < 0.01) with higher phytase effect in NC as compared with PC.Neither diet nor phytase impacted excreta moisture content on d 18 or 21(P> 0.05). Solid phase microextraction gas chromatography-mass spectrometry(SPME-GC-MS) analysis of gaseous emissions on d 39 indicated no difference in the emission of alcohols, aldehydes, ketones, volatile fatty acids and phenols between treatments(P> 0.05). The results indicate that phytase has greater benefits when formulated using nutrient matrix values as compared with adding it over the top in an already nutrient sufficient diet. The later method would be expected to increase feed costs without concomitant performance benefits.