Effects of dietary crude protein level on odour from pig manure

Abstract

The objective of this study was to determine the effects of dietary crude protein (CP) level on odour emission, odour intensity, hedonic tone, and ammonia emission from pig manure and on manure composition (pH, total nitrogen, ammonium, volatile fatty acids, indolic, phenolic and sulphur-containing compounds). An experiment was conducted with growing pigs (n ¼ 18) in a randomised complete-block design with three treatments in six blocks. Treatment groups were 12%, 15% and 18% CP diets. Barley was exchanged for soya-bean meal. Crystalline amino acids (AA) were included in the 12% CP diet up to the level of pigs' requirement; the same amount of AA was added to the 15% and 18% CP diets. Pigs with an initial body weight (BW) of 36.5^3.4 kg (mean^s.d.) were individually penned in partly slatted floor pens and offered a daily feed allowance of 2.8 £ maintenance requirement for net energy (NE: 293 kJ/kg BW 0.75 ). Feed was mixed with water, 1/2.5 (w/w). Faeces and urine of each pig were accumulated together in a separate manure pit under the slatted floor. After an adaptation period of 2 weeks, the manure pits were cleaned and manure was collected. In the 5th week of the collection period, air samples for odour and ammonia analyses, and manure samples were collected directly from each manure pit. Air samples were analysed for odour concentration and for hedonic value and intensity above odour detection threshold. Manure samples were analysed for volatile fatty acids, and indolic, phenolic and sulphurous compounds, ammonium and total nitrogen concentrations. Reducing dietary CP from 18% to 12% lowered odour emission ( P , 0.05) and ammonia emission ( P ¼ 0.01) from pig manure by 80% and 53%, respectively. Reduced dietary CP decreased total nitrogen, methyl sulphide, carbon disulphide, ethanethiol, phenol, 4-ethyl phenol, indole and 3-methyl indole concentrations in the manure ( P , 0.05). Volatile fatty acids and cresols concentrations in the manure of pigs fed different dietary CP levels were similar. A reduction of dietary CP and at the same time providing essential AA is an option to reduce odour emission as well as ammonia emission from pig manure.

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 net height of the lower compartment (storage container) was 41.5 cm and the net height of the upper compartment was 41.5 cm. A schematic view of the odour sample collection system, which was adapted from Le et al (2007), is illustrated in Figure 1.…”

Nitrogen balance, ammonia and odor emissions ingrowing pigs fed reduced protein diets

“…Le et al (22) mostraron que alimentar a los cerdos con dietas con 18 y 12 % PC disminuía el pH de las excretas de 7.83 a 7.10. En contraste, otros autores (23) no pudieron detectar diferencias en el pH del purín cuando alimentaron a cerdos en crecimiento con dietas cuyo contenido de PC fue del 19 o del 22 %; esta falta de efecto, pudiera estar asociada al hecho de que el rango en los niveles de PC que usaron fue más elevado y estrecho que en otros estudios, incluyendo éste.…”

Strategies to control odours in livestock facilities: a critical review

“…It has been widely demonstrated that FC incorporated into pig diets increases the volatile fatty acid (VFA) content in manure (Clark et al, 2005;Kerr et al, 2006;O'Connell et al, 2006), but it remains unclear whether the odour profile is affected. Whereas Lynch et al (2008) obtained a 41% increase of odour emissions when sugar beet pulp was added to pig diets, a non-significant effect of FC was found by Clark et al (2005) and Le et al (2007). As acknowledged by Leek et al (2007) and Le et al (2008), the balance between dietary FC and CP plays an important role on odour production and emission.…”

“…It has been demonstrated that reducing crude protein (CP) can effectively reduce the proportion of excreted nitrogen, which is associated to lower ammonia emissions, not only at the housing level, but also during manure storage and land application of manure (Hayes et al, 2004;Le et al, 2007). However, the cause and effect relationship between feed characteristics and the excretion of odorous compounds is not so evident.…”

“…Feeding pigs with low crude protein diets reduced odour concentration from 30 to 80%, according to Hayes et al (2004) and Le et al (2007). On the other hand, some authors reported that odour concentration and offensiveness increased when low-CP diets supplemented with synthetic amino acids were used (Otto et al, 2003;O'Connell et al, 2006).…”