Phosphorus Availability and Requirements in Pigs

Posted in: Environment by admin on January 1, 1991 | No Comments

As the phosphorus (P) available or digestible for the pig in feed originating from plants additional P from inorganic sources is to be added to the diet. In order to lower P excretion, the pigs requirements have to be well known and the digestibility of P well assessed in the feedstuffs from plants, animal or feed phosphate. The results of digestibility tests made on many feedstuffs are presented. And the apparent digestibility varies from 10 to 50% for plant origin feedstuffs and from 65 to 90% for feedstuff of animal origin and feed phosphates. The factors affecting the P digestibility are the origin of feedstuff, the concentration of phytate and of the total P and the presence of phytase. Plant phytase and also microbial phytase enhance the digestibility of P. Using 1000 units of microbial in the pigs’ feed will enhance the P digestibility by 20%. The requirements for P for the pig have also to be well determined and can vary according to the physiological stages, to environment, genotype (very lean pigs will have slightly higher requirements of 5 to 6%), feeding level and major ingredients used (wide variation can be observed between countries). Recommendations on P requirements should be made considering the digestibility of P and not the total P available.

Phosphorus requirements and absorption by pigs is well presented. The approach using the P digestibility of feedstuffs to meet the pig’s requirements is an efficient one toward excessive and unnecessary P excretion.

Assessment of dustfall collectors used in livestock buildings.

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The relative collection efficiency of several different types of dustfall collector was assessed over different collection intervals in a piggery. Flat plate collectors and collectors with sidewalls 10 and 50 mm high were placed on a slow-speed turntable to minimize positional effects. For each sampler type, collection intervals of 1, 3, 6 and 12 wk were used. The collection medium was generally a 47 mm glass fibre filter located on a 75 mm diam. aluminium disc. Cellulose nitrate membrane filters were used for one treatment. The dust sedimentation rate determined from the weekly samples varied from 80 to 200 mg m-2h-1 over the 12 wk period. Dust deposits on the filters varied linearly with time from 2.3 mg/cm2 of collector surface for the 1-wk interval to 27.9 mg/cm2 over 12 wk. The measured dust sedimentation rate was about 3.0% less on the membrane filters than on the glass fibre filters and also for those collectors with the 50 mm high sidewall when compared with the flat plate collectors. The length of sample collection interval did not significantly affect the measured dust sedimentation rate. It is suggested that handling errors and edge effects may affect accuracy when deposits are greater than about 7 mg/cm2 of collector surface.

Towards an Improved Utilization of Dietary Amino Acids by the Growing Pig

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The utilization of dietary amino acids in commercial pig production is relatively low. An experiment done on gilts weighing 50 kg and 6 different diets were given; on average the ingested dietary protein was utilized with a 30% efficiency and on average the lysine was utilized with an efficiency lower than 45%. Different physiological processes contribute to the incomplete utilization of the amino acid (excretion of unabsorbed dietary AA, absorption of chemically-unavailable compounds derived from AAs, use of Aas for body protein maintenance, use of AA for the synthesis of non-protein N compounds, preferential catabolism of AAs for energy supply, inevitable AA catabolism and catabolism of Aas supplied above the amount required for the maximum rate of protein retention). The development of AAs digestibility assays is also presented. Improvement in the digestibility of AAs is needed and will probably come through a better understanding of the processes involved.

The processes and methods involved in Aas digestibility and digestibility assays are complex and complicated. Fundamental work is needed to investigate the reactions and physiological processes involved.

Removal of airborne dust by electrostatic precipitation in pig housing.

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The electrical resistivity, explosibility and collection efficienty were determined for swine dust to investigate the use of electrostatic precipitation in removing airborne dust from swine housing air. Four other organic dusts used in the resistivity and collection experiments were: flour, icing sugar, corn starch and milk powder. The electrical resistivity for each of the dusts was within the “medium” resistivity range; the range that produces the best conditions for collection by an electrostatic precipitator. An electrostatic precipitator collected the flour, icing sugar, corn starch, milk powder and swine housing dust with mass collection efficiencies of: 92.5%, 23.9%, 71.0%, 45.7% and 67.3%, respectively. For each of the five dusts the particles less than 1um, were collected with less efficiency than particles greather than 1um. An explosiveness test indicated that the swine housing dust was explosive and care should be taken when being handled.

Computer Simulation Model of Swine Production Systems: 1. Modeling the Growth of Young Pigs

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Protein growth and its characteristics are essential in swine production systems as protein is the first contributor of carcass lean, the most valuable component of pig’s body. This model help finding optimal diets that minimize the nutrient inputs while maximizing the lean growth performance.

Verifying a lumped-parameter model in a ventilated enclosure with swine dust.

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The objective of this study is to verify a lumped-parameter model which was derived for predicting airborne dust concentrations at any location within a ventilated airspace using dust as a test dust. Average equilibrium airborne dust concentrations were predicted as a function of ventilation and dust generation rates. Time-dependent airborne dust concentrations at a designed location also were predicted from ventilation and dust generation rates.The model calculation solved as a 3-D lumped form of control volumes represented conservation of airflow rate. Swine dust used in this project has an average aerodynamic diameter of 2 um and 95% of the dust particles are less than 5 um in size while appoximately 45% of the particles are 2 um in diameter. Statistical analysis revealed that both ventilation rate and dust generation rate have a significant effect on airborne dust concentration.

Anglo-Dutch experiments on odour and ammonia emissions following the spreading fo piggery wastes on arable land.

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Experiments were done with researchers from the Netherlands and UK to evaluate odour and ammonia emissions (OAE) following spreading of pig slurry on arable land. Emphasis of the Netherlands team was directed toward ammonia reduction where the UK team paid more attention to odours. Tilling is a good way to abate OAE as the slurry surface exposed to air is greatly reduced furthermore the contact of the ammonium with soil colloids is increase thus reducing ammonia emissions. Investigations were done with manure application on clay soils and also in sandy soils and different tillage techniques (plough, rotary harrow and tines) were tested for their abilities in OAE control. Various manure management techniques were also tested for ammonia emissions (solid-liquid separation, pit storage under slatted floor for the entire fattening period and weekly manure removal and storage in enclosed tank).
The results showed that any delay of incorporation results in higher total OAE; the longer the delay, the more OAE. Incorporation by ploughing gave better results in clay soils, as for sandy soils both ploughing and rotavating were interesting. The cultivator technique was the least effective one on clay and sandy soils.
However for odours, only substantial reductions were noted for direct incorporation on clay soil and delaying incorporation did not effect the emission level significantly. Significant differences were obtained with different machinery and ploughing showed to be the most effective for odour abatement. For the manure management techniques, no substantial difference in ammonia emission were measured between when the manure was removed weekly compare with the manure being stored for the whole fattening period. The separation technique showed to be more effective in reducing ammonia emissions after landspreading as the losses from urine were less than 20% compared to slurry (control) and the losses from the faeces where equivalent to the one of the control.

This work is interesting and combined the expertise from researchers from 2 European countries that had mostly different concerns, ammonia emissions for the Netherlands and odours for the UK and different expertise, the UK gained expertise in olfactometry and measurement of emissions during spreading and the team from the Netherlands benefited from the micrometeorological and wind tunnels method used by the AFRC-IGER team

Concentration of respirable dust and bioaerosols and identification of certain microbial types in a hog-growing facility.

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In order to assess the effects of ventilation rate, temperature, relative humidity and source of air on bioaerosol levels and dust with particle size < 10 um, a total of 120 pigs housed in 12 pens in two separate rooms were used. Pigs averaged 30 kg initially and the trials were discontinued when 20% of the pigs were marketed. A six-stage Andersen sampler and a light scattering particle counter were used to determine bioaerosols and respirable dust (0.1-10 um), respectively. Total bioaerosols were assessed using Trypticase Soy Agar, Potato Dextrose Agar was used for fungal aerosols and Baird-Parker Agar used for isolation of Staphylococcus aureus. Moulds amounted to less than 1% of total microoganisms. Gram positive bacteria made up 72% of the bacterial isolates. Respirable dust was not correlated with respirable bioaerosols. Ventilation rate (2, 5 or 8 changes per hour) did not affect bioaerosol level or respirable dust. Total bioaerosols were significantly reduced (P<0.05) in higher temperatures only. Relative humidity did not influence total bioaerosols but in one series respirable bioaerosols were significantly (R = 0.53) (P<0.05) correlated with RH. Total bioaerosols were not different in outside air or attic air.

Methods for Evaluating Odor from Swine Manure

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A good review of the odour evaluation methods is given. The magnitude method and the ranking methods were used to evaluate manure aeration and additive addition at different rates. The panel members in the first case had to give a magnitude estimation of the odour using a scale from 1 to 9 with the distilled water being assigned 1 on the scale and untreated manure being 7 on the scale. Toward the end of the testing, ranking evaluation was also done comparing only 2 samples and deciding which on is the more offensive. The ranking method appeared to be the more precise method than magnitude however ranking doesn’t give any information on the differences noticed.

Environmental Effects of Ammonia

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Direct effect of ammonia emission can be remarked only in cold climate like in the northern part of Scandinavia or in cold winters. Damages can be remarked on the vegetation under those conditions and red or reddish brown colouring can be seen on coniferous trees. In mild climate the trees generally recover in the summertime. The indirect effects of ammonia are more widespread and serious and result on ammonium deposition on ecosystems. Acidification and nitrogen enrichment of the soil can result from nitrogen deposition on weakly buffered ecosystems. This phenomena can result in the disappearance of many plant species. Competition between slow growing and fast growing plants will be seen and changes can be observed for example from a heath- and peatlands into grasslands.
Ammonia emission should be considered seriously particularly where livestock density is high and fragile ecosystems are close by. The acidification effects have already caused problems in some areas in The Netherlands and Germany.