Odour flux from litter of broiler chickens fed diets differing in protein levels and additives

The effect of dietary crude protein (CP) and additives on odour flux from broiler litter was investigated using 180 day-old Ross 308 male chicks randomly allocated to five dietary treatments with three replications of 12 birds each. A 5×3 factorial arrangement of treatments was employed. Factors were: diet (low CP, high CP, high CP+antibiotic, high CP+probiotic, high CP+saponin) and age (15, 29, 35 days). Low CP (LCP) and high CP (HCP) diets differed in CP levels by 4.5-5%. The low CP diets were supplemented with L-valine, L-isoleucine, L-arginine, L-lysine, D,L-methionine and L-threonine. The antibiotic used was Zn Bacitracin, the probiotic was a blend of three Bacillus subtilis strains and the saponin came from a blend of Yucca and Quillaja. Odorants were measured from litter headspace using a flux hood and selective ion flow tube mass spectrometry (SIFT-MS). Results were log tranformed and analysed by two-way ANOVA with repeated measures using JMP statistical software v.8, and means were separated by Tukey's HSD test at P<0.05.The results showed that LCP group produced lower flux of dimethyl amine, trimethyl amine, H2S, NH3 and phenol in litter compared to HCP group (P<0.05). Similarly, HCP+probiotic group produced lower flux of H2S (P<0.05) and HCP+saponin group produced lower flux of trimethylamine and phenol in litter compared to HCP group (P<0.05). The dietary treatments tended (P=0.065) to have higher flux of methanethiol in HCP group compared to others. There was a diet x age interaction for litter flux of diacetyl, acetoin, 3-methyl-1-butanol, 3-methylbutanal, ethanethiol, propionic acid and hexane (P<0.05). Concentrations of diacetyl, acetoin, propionic acid and hexane in litter were higher from LCP group compared to all other treatments on d 35 (P<0.05) but not on days 15 and 29. Thus, the low CP diet, Bacillus subtilis based probiotic and Yucca/Quillaja based saponin were effective in reducing the emissions of some key odorants from broiler litter.

Characterisation and quantification of changes in odorants from litter headspace of meat chickens fed diets varying in protein levels and additives

The effect of dietary crude protein (CP) and additives on odor flux from meat chicken litter was investigated using 180 day-old Ross 308 male chicks randomly allocated to five dietary treatments with three replicates of 12 birds each. A 5 × 3 factorial arrangement of treatments was employed. Factors were: diet (low CP, high CP, high CP+antibiotic, high CP+probiotic, high CP+saponin) and age (15, 29, 35 days). The antibiotic used was Zn bacitracin, the probiotic was a blend of three Bacillus subtilis strains and the saponin came from a blend of Yucca and Quillaja. Odorants were collected from litter headspace with a flux hood and measured using selective ion flow tube mass spectrometry (SIFT-MS). Litter moisture, water activity (Aw), and litter headspace odorant concentrations were correlated. The results showed that low CP group produced lower flux of dimethyl amine, trimethyl amine, H2S, NH3, and phenol in litter compared to high CP group (P < 0.05). Similarly, high CP+probiotic group produced lower flux of H2S (P < 0.05) and high CP+saponin group produced lower flux of trimethylamine and phenol in litter compared to high CP group (P < 0.05). The dietary treatments tended (P = 0.065) to have higher flux of methanethiol in high CP group compared to others. There was a diet × age interaction for litter flux of diacetyl, 3-hydroxy-2-butanone (acetoin), 3-methyl-1-butanol, 3-methylbutanal, ethanethiol, propionic acid, and hexane (P < 0.05). Concentrations of diacetyl, acetoin, propionic acid, and hexane in litter were higher from low CP group compared to all other treatments on d 35 (P < 0.05) but not on d 15 and 29. A high litter moisture increased water activity (P < 0.01) and favored the emissions of methyl mercaptan, hydrogen sulfide, dimethyl sulfide, ammonia, trimethyl amine, phenol, indole, and 3-methylindole over others. Thus, the low CP diet, Bacillus subtilis based probiotic and the blend of Yucca/Quillaja saponin were effective in reducing the emissions of some key odorants from meat chicken litter.