By now all intensive pig and poultry farmers in Europe are familiar with the term Integrated Pollution Prevention and Control (IPPC). Generally when IPPC is considered, we think of paperwork or complicated calculations relating to how much slurry or farm-yard manure can be spread on crops or neighbouring farm land! However, nestled unobtrusively in the application form, pig farm applicants are required to insert the number of sows, weaners, growers and finisher places on the unit.

This information, together with the appropriate factor (already available on the form), allows for the simple calculation of the total ammonia emission from the farm measured in kg per year. In addition, the applicant is also required to summarise what measures are being taken to control odour release from the unit.

When the application form is sent off and after some interaction with the appropriate departmental body, the permit is issued containing numerous conditions - outlined in the section entitled ‘Improvement Plan’. Permit holders must review their emissions of ammonia and/or odour and suggest how the current levels can be reduced. Most farmers expected that they would be required to fix faulty slurry tanks or eliminate dirty water run-off to waterways – but what can be done to reduce the impact of odour or ammonia emissions from the unit at limited cost?

 

Low protein strategy
The excretion of ammonia is directly related to the amount of protein consumed by the pigs. For thatreason, guidance notes for those applying for an IPPC license indicate that the pigs must have access to at least two diets of reducing protein status between 30 kg liveweight and 105 kg at slaughter or three diets if slaughter weights are heavier.

 

This requirement attempts to ensure that the protein intake of the animal reflects their ability to grow lean tissue. However, when reducing the protein level of the diet, it is vital that the nutrient intake of the animal is not compromised. Le et al., (2007b) have shown that by reducing crude protein intake of the pig, the odour emissions from the manure can be substantially reduced (Table 1); however the performance of the pigs on the low protein diets was severely compromised.
   

If a low protein strategy is contemplated, it is essential that adequate diet specifications for the animals on the unit are adhered to. Universal guidelines should be challenged if animal performance, animal welfare or unit profitability is compromised. Fortification of diets with crystalline amino acids can allow performance to be maintained even in diets where the protein level has been reduced substantially against traditional norms, as Le et al. showed.

 

However, this later work showed that the inclusion of sulphur-containing amino acids at high levels led to highly odorous slurry. Nutritionists must be aware of the impact that dietary changes have on slurry odour and ammonia emission characteristics, while maintaining physical performance economically.

 

Inclusion of barley
Recent research by University College Dublin, Ireland has shown that the inclusion of barley in the diet can result in a substantial reduction in the level of odorous compounds released from the slurry produced by pigs. Further work from the same source has shown that when barley or wheat, together with soybean is fed to pigs from 58 to 89 kg, the level of odour production was significantly higher when wheat was the cereal source (Table 2).
Amazingly, the inclusion of a β-glucanase enzyme resulted in an elevation of the odour output of slurry from pigs fed a barley-based diet. The authors concluded that the β-glucans were being used as a nutrient source by the bacteria in the hindgut of the pigs, thus capturing the ammonia nitrogen into bacterial protein, rather than forming urea which subsequently would be broken down to ammonia and odour in the slurry during storage.

 

Feeding whey
Farmers feeding whey should take note of the research carried out by Pierce et al. in 2006, where a source of lactose (86% whey permeate) was included in the diet at levels between 0 and 16%. The basis of the study was that as older pigs have a limited ability to digest lactose in the small intestine, the lactose must be acting as a substrate for bacterial activity in the hindgut.

 

The results showed that the addition of lactose significantly reduced the level of ammonia released from the slurry over the first four days of storage, although the figures for ammonia released over ten days were not significantly affected. This initial reduction in ammonia release could be very important in housing where the slurry is flushed out on a very regular basis to be held in external, covered tanks.

 

Yucca extracts
The addition of yucca extract (in this case De-Odorase^®, Alltech) to animal feeds is not a new concept, as the product has been available for many years. Extracted from the Yucca Schidigeraplant, the product is added to the diet at 120 g per tonne and has been shown to substantially reduce the level of ammonia and odour released from the slurry storage facilities.
 In research, presented to the European Association of Animal Production, Power and Tuck (1994) showed that by adding yucca extract to the diet of pigs from 30 to 92 kg, the ammonia level in the atmosphere of the pig house was reduced from 30 ppm at the beginning of the trial to 20 ppm at the end (Table 3). In addition, their research showed that the reduction of ammonia levels in the atmosphere occurred after a period of nine weeks and continued to decline over a seventeen-week period.

 

A further significant feature of yucca extract addition was the improvement in growth rate that was recorded. This feature of improved physical performance was reported by Van Den Berghe (1999) who reported a growth rate of 687 g per day for pigs fed the control diet versus 694 g per day for those given the yucca extract treatment. The author reported that the inclusion of yucca extract was associated with a significant reduction in the number of ‘inflamed’ lungs when the pigs were slaughtered (44% control versus 9% yucca extract treatment, P<0.001).

 

Ammonia levels
This improvement was associated with the reduction in the ammonia levels in the air within the piggery. The significance of air quality on the performance of pigs was reported by Lee et al., 2005. Their work (Table 4) showed that where pigs were raised in an atmosphere of elevated ammonia and dust, average daily gain and feed conversion efficiency deteriorated.

It is inevitable that environmental issues will continue to dominate European agriculture. Hence, it is important that producers adopt strategies to ensure that they comply with IPPC regulations.

 

Dietary protein manipulation through raw material and crystalline amino acids, inclusion of some barley or lactose, together with the addition of products to help reduce the level of ammonia and/or odour emitted from pig units. Importantly, yucca extract has been shown to give improvements in physical animal performance that will minimise any negative impact on unit profitability.