Modelling of biological nitrogen removal from the liquid fraction of pig slurry in a sequencing batch reactor

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Biological nitrogen removal through nitrification–denitrification is a treatment alternative that can be considered for scenarios in which there is a nitrogen surplus linked to pig manure management. Studies found in the literature referring to the treatment of the liquid fraction of pig slurry using sequencing batch reactors (SBRs) were reviewed and typified. Mathematical modelling of this treatment was carried out considering: nitrite and pH as state variables; nitrification and denitrification as two-step processes; surface limited kinetics for hydrolysis and dependence for the heterotrophic biomass yield, as well as for the anoxic maximum growth rate, on the electron acceptor. Sensitivity analysis permitted identification of the parameters that had the greatest influence on the response of the model under specific test conditions. These were subsequently assessed, principally using respirometry. Finally, model-based predictions were contrasted with results obtained in a lab-scale SBR following two different operational strategies. The availability
of biodegradable organic substrates for complete denitrification was identified as one of the main limiting factors of the treatment, even when treating raw waste. Low aeration intensity during oxic periods made it possible to mainly conduct the process along the nitrite route and to thereby reduce the organic and oxygen requirements of the process.

For more information the full article can be found at http://www.sciencedirect.com/science/journal/15375110

Geotextile Filtration Performance For Lagoon Sludges and Liquid Animal Manures Dewatering

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A geotextile filtration testing method termed a hanging‐bag test was used to treat dairy lagoon sludge, swine lagoon sludge, liquid dairy manure, and liquid swine manure. Hanging‐bag performance was evaluated by: (1) determining solids and plant nutrient mass retention efficiencies, (2) quantifying the overall volume reduction, and (3) characterizing the dewatered manure or liquid dairy manure, geotextile filtration reduced the total influent volume to less than 1%, concentrated the solids and nutrients in the dewatered material 16 to 21 times greater than the influent, and retained 38.4% of total solids, 25.8% of total ammoniacal nitrogen, and 45.0% of total phosphorous, making this an effective liquid‐solid separation technique.

Equilibrium Sampling Used to Monitor Malodors in a Swine Waste Lagoon

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The concentrations of malodorous compounds in a 0.4-ha
anaerobic lagoon that received waste from approximately 2000
sows were monitored during the late summer to late fall of 2006. It was found that the increases in the
concentrations of malodorous compounds in the wastewater during the fall were due to reduced degradation by
lagoon bacteria, less wind stripping of volatile compounds from the lagoon surface due to lowering of the lagoon
surface after crop application, and/or reduced evaporation of malodorous compounds due to falling temperatures.

A second look at the influence of birth weight on carcass and meat quality in pigs

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Birth weight and within-litter variation in birth weight are important economic traits in pig production. Genetic selection for large litters during the last decades has lowered mean birth weight, which mainly results from a higher competition of the fetuses in utero reflected also by an inverse correlation of birth weight and litter size (e.g. Milligan, Fraser, & Kramer, 2002; Quiniou, Dagorn, & Gaudre, 2002). Low birth weight, however, is associated with decreased survival and lower postnatal growth rates (e.g. Herpin, Damon, & Le Dividich, 2002; Milligan et al., 2002; Pond & Mersmann, 1988; Quiniou et al., 2002; Ritter & Zschorlich, 1990). In addition, pigs at market weight originating from piglets of low birth weight develop a lower carcass quality in terms of higher fat deposition and lower lean accretion compared with their middle or heavy weight littermates (Bee, 2004; Gondret et al., 2006; Hegarty and Allen, 1978; Kuhn et al., 2002; Poore & Fowden, 2004; Powell and Aberle, 1980, 1981; Rehfeldt and Kuhn, 2006). Low birth weight results from intrauterine growth retardation during gestation. It has been shown previously that small piglets form a lower total number of skeletal muscle fibres during prenatal development compared with their larger littermates (Gondret et al., 2006; Handel & Stickland, 1987; Wigmore & Stickland, 1983). From recent studies, it has been suggested that it is the low number of muscle fibres, which restricts the potential of postnatal lean growth and therefore allows to deposit increased amounts of fat (Rehfeldt & Kuhn, 2006). In addition, tendencies towards lower meat quality in terms of tenderness and water holding capacity have been observed at slaughter, when the piglets were small at birth (Gondret et al., 2005; Gondret et al., 2006; Rehfeldt & Kuhn, 2006), which may be associated with accelerated muscle fibre hypertrophy because of low fibre number. The studies on the influence of birth weight mentioned above have in common, that the number of animals used in the experiments were not very large (5–32 pigs per birth weight group born to 13– 16 sows) and the variation in the traits of interest caused by the dam/litter has not always been considered in the statistical models. Therefore, this study was conducted using a larger set of pigs from 63 litters in total to re-examine the consequences of birth weight for ultimate carcass and meat quality. In order to accomplish this, the offspring (n = 378) of the 63 sows were assigned to three birth weight groups; 25% low weight, 50% middle weight, and 25% heavy weight, with runts (<800 g) being excluded. Low weight pigs exhibited the lowest postnatal growth performance, the lowest lean mass and the greatest degree of fatness in terms of perirenal fat compared with medium weight and heavy weight pigs. Only in females, but not in male castrates, the lean percentage was highest in heavy weight pigs. Characteristics of longissimus muscle technological quality declined either in low weight (pH, drip loss) or heavy weight (conductivity, lightness) compared with medium weight pigs. In contrast, intramuscular fat percentage (IMF) was highest in low weight pigs. The results suggest that the most desirable carcass composition is obtained with heavy weight pigs, whereas optimum technological pork quality, except for IMF, is achieved with medium weight pigs.

The impact of different natural zeolite concentrations on the methane production in thermophilic anaerobic digestion of pig waste

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The effect of natural zeolite on the thermophilic anaerobic decomposition of pig waste was
investigated. In particular, the effect of adding different amounts of zeolite on the increase
of methane production of waste. It was found that the results of adding zeolite had an effect not only on the toxicity of
ammonia and on the C/N proportion but also on the regulation of acidity (pH) of the pig
wastes.

A Partial Equilibrium Model of the Linkages between Animal Welfare, Trade and the Environment in Scotland

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Mechanical refrigeration, seasonality, and the hog–corn cycle in the United States: 1870–1940

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This paper examines the role of mechanical refrigeration in seasonality and structural change in the U.S. hog–corn
cycle, 1870–1940. This period covers an era in which the widespread adoption of mechanical refrigeration greatly affected the ability to store and transport perishable commodities. These developments in turn altered the seasonal production and price structure for many commodities, including pork. We use a new class of time series models, time-varying smooth transition autoregressions (TV-STARs), to document both the structural change and the nonlinear features observed in seasonal patterns for the U.S. hog–corn price relationship during the late nineteenth and early twentieth centuries.

Effects of season and distance moved during loading on transport losses of market-weight pigs in two commercially available types of trailer

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This study evaluated effects of trailer design and season on physical indicators of stress during loading and unloading and transport losses (dead and nonambulatory pigs) in market-weight pigs (BW = 129.6 ¡À 0.40 kg). A total of 109 trailer loads of pigs (n = 17,256 pigs) from 1 farm were used in a randomized complete block design with a 2 ¡Á 4 factorial arrangement of treatments: 1) trailer design (pot-belly vs. straight-deck) and 2) season (spring vs. summer vs.
fall vs. winter). A subset of loads (n = 42) was used to examine effect of distance pigs were moved during loading [short ( indicators of stress and transport losses. This study was conducted on 7 d per season at 1 farm with 4 loads (2 on pot-belly and 2 on straight-deck trailers) being transported each day to 1 commercial packing plant. Pigs from different farm groups were mixed on the trailer and provided with 0.45 m2/pig floor space during an approximately 4-h journey to the plant. The percentage of pigs exhibiting open-mouth breathing, skin discoloration, and muscle tremors was recorded during loading and unloading. Additionally, dead pigs on arrival at the plant and nonambulatory pigs at the farm
and at the plant were recorded. Effects of trailer design on open-mouth breathing and skin discoloration during unloading were dependent on season (trailer design ¡Á season interaction; P < 0.05). Pigs unloaded from
pot-belly trailers had a greater (P < 0.05) incidence of open-mouth breathing in the spring and summer and a
greater (P < 0.05) incidence of skin discoloration in the spring, summer, and winter than pigs unloaded from straight-deck trailers. The incidence of total nonambulatory pigs at the plant was greater (P < 0.05) in the winter than in the spring and summer. The long compared with short distance moved treatment resulted in a greater (P ¡Ü 0.001) incidence of open-mouth breathing and skin discoloration during loading and tended (P = 0.06) to increase the incidence of nonambulatory pigs at the farm. However, there was no effect of trailer design, season, or loading distance on total losses at the plant. In summary, physical indicators of stress (open-mouth breathing and skin discoloration) were increased with the long distance moved during loading treatment and were greater during unloading for
pot-belly than straight-deck trailers; however, trailer design, season, and loading distance had minimal effects on total transport losses.

For more information the full article can be found at http://jas.fass.org/

The effect of feeder type and change of feeder type on growing and finishing pig performance and behaviour

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Reduction in feed intake at weaning has been reported to result in a post-weaning ‘growth check’ (Pluske et al., 1997). This reduction in intake and growth rate is likely to be caused by a number of factors including the stress of being transported and mixed (Ekkel et al., 1995; Bilkei et al., 1997; Mardarowicz, 1985) and abrupt changes in both the diet and environment, for example, feed being offered from unfamiliar feeders (Pluske and Williams, 1996). A similar growth check is likely to occur when pigs are transferred to finishing accommodation. Despite the evidence to indicate that ‘wean to finish’ accommodation would be advantageous in terms of production performance (Ekkel et al., 1995; Bilkei et al., 1997; Mardarowicz, 1985), there are few units where pigs could be housed in the same accommodation from weaning to finish. Consequently producers aim to minimize the extent of change of diet and environment, thereby reducing the stress of transportation and re-housing and ultimately the ‘growth check’. The aim of this study was to compare the performance and behaviour of pigs offered feed in the same type of feeder from weaning to finish with those offered feed from two different types of feeder. A total of 640 pigs in 32 pens of 20 pigs per pen were used to investigate the effects of two feeder types and changing or not changing the feeder type at 10 weeks of age on growth performance and behaviour in the periods from 4 to 10, 10 to finish (22) and from 4 to finish (22) weeks of age, respectively. The two feeder types tested were a ‘wet and dry’ single-space (S) feeder and a ‘dry’ multi-space feeder (M). In the period 4–10 weeks of age feeder type had no significant effect on growth performance though pigs on the ‘dry’ multi-space feeder tended to exhibit significantly better feed efficiency from 4 to 7 weeks of age. In the first week after changing accommodation the growth rate of pigs on all treatments was depressed (compared to the last 3 weeks of the grower period) and was reduced a further 60 g/day when the feeder type was changed. However, the “feeder” effect was transitory and had no effect on overall finisher performance except for pigs changed from a ‘dry’ multi-space feeder to ‘wet and dry’ single-spaced feeder. These animals had significantly faster growth rate over the finisher phase.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/anifee/issues

Synthetic lying mats may improve lying comfort of gestating sows

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A prototype lying mat as an alternative to straw bedding for improving sow lying comfort was evaluated
using a dynamic group of 47 gestating sows housed in a pen with 5 communal lying areas. Mats were
installed in 3 lying areas while the concrete floors of the remaining lying areas remained uncovered (period
1). After 5 weeks the position of the lying mats was rotated (period 2). It was concluded that under conditions of this experiment covering concrete floors with synthetic mats appeared to improve sow lying comfort. It is questionable whether this finding can be generalised to other (climatic) conditions.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues