Organic mineral supplements in pig nutrition

Introduction

The progress of the pig industry in the last ten years has been extraordinary, mostly due to necessity to ensure survival. The pig producer in the year 2000 and beyond must be adaptable to the ever-changing factors affecting production as well as realising that today we are not merely producing pigs, but meat for human consumption. This paradigm shift in understanding of the output of our business is essential in understanding hat is required to be successful for the future. Decisions in all aspects of the business must be made in the light of what will be the minimum requirements in the future and what will give the maximum return in the long term. Those that have this vision in mind and work toward it will be the producers in the future.

Bunge Meat Industries is the largest piggery in Australasia, producing 950,000 carcasses per year from a sow population of 55,000 sows. The company is fully integrated with a feed mill, abattoir and boning room located at Corowa on the border of New South Wales and Victoria. The company has a fully funded Research and Development facility and Technical Services group that allow us to evaluate new products and technologies using our own pigs and tailoring the research for our specific production systems.

This paper will provide an update of our results using Bioplexes and examples of how we have adopted these outcomes within the BMI production system.


The theory behind using organic trace minerals

Traditionally, inorganic salts of minerals such as oxides, sulphates and carbonates have been added to the diet to provide levels sufficient to prevent deficiencies or improve performance. The level of supplementation has been calculated through many experiments based on inorganic minerals and the known interactions among them. These minerals are broken down during digestion into free ions that are then absorbed in the intestine.

The free mineral ions released during digestion may also complex with other dietary molecules and become difficult to absorb or, if completely complexed, totally unavailable to the animal. Thus, the availability of the element may vary substantially. Because of these uncertainties, the levels provided in the diet are often higher than the minimum required for optimum performance, often resulting in over-supply and unnecessary wastage with obvious environmental impact.

As a consequence, there has been increasing interest in the role of organic or chelated sources of trace elements, frequently described as proteinates. They are normally produced by first hydrolysing a protein source, which results in the formation of a hydrolysate containing a mixture of amino acids and peptides of varying chain length. The reaction of a metal sulphate with the hydrolysate under the appropriate conditions results in the formation of complexes containing chelated metal ions (Power and Horgan, 2000).

Many minerals occur in nature as proteinates or chelates. Chelates may utilize peptide or amino acid uptake pathways rather than normal mineral ion uptake pathways in the small intestine. This prevents competition between minerals for the same uptake mechanisms. Not only is bioavailability therefore higher, but also these mineral forms are more readily transported and hence their intestinal absorption is also enhanced. They are more stable and are protected biochemically from the adverse reactions with other dietary nutrients that could reduce their rate of absorption. It is also thought that they can be specifically targeted at certain organs, tissues or functions in the body. This makes them most attractive for use in pig diets.

The increase in bioavailability of organic minerals compared with inorganic sources has been shown in many studies (Du et al., 1996; Shi et al., 1995). However, there is only indirect evidence supporting the theory that the organic minerals are absorbed via the amino acid and peptide absorption pathways. This lack of direct evidence does allow the possibility of other theories of absorption to be developed. Despite this lack of direct evidence, organic trace minerals have shown positive production responses in a number of studies (Table 1).


Table 1. Summary of research demonstrating performance and reproduce the responses to organic trace minerals in pigs.




Current thinking and research findings

The use of organic minerals has slowly gained acceptance over the last 15 years as the weight of scientific evidence shows the advantages of this form of mineral. The key areas where organic minerals can play a part in pig nutrition are improvement of grower and finisher performance, increasing the consistency of performance in the breeder herd, improving the quality of pig meat and reducing the impact of pig production on the environment.


PERFORMANCE RESPONSES

Comparisons of copper (Cu) sulphate (CuSO4) and Bioplex Cu (proteinate) have been conducted at Bunge for the dual purpose of evaluating performance responses and mineral excretion. The addition of copper sulphate and Bioplex Cu to grower finisher diets increased growth rate by 5% and feed conversion by 3% (Table 2). There was no difference in performance between the pigs given Bioplex Cu diets and those fed diets containing 200 ppm copper sulphate. These data tend to confirm reports from many trials conducted around the world and allow us to commercially evaluate the cost effectiveness of the product.


Table 2. The growth performance and carcass characteristics of male pigs fed diets containing two levels of Cu sulphate and Bioplex Cu from 28 kg until slaughter.



IMPROVING SOW PERFORMANCE

At the start of 1999, BMI introduced the use of the Alltech products Sel-Plex and Bioplex Iron (Fe) into the breeder premix used in the gilt pool and the sow and boar diets. The breeder premix already contained 200 ppb chromium picolinate. Figure 1 is a graph derived from PigPulse using the weighted born alive for all five sites at BMI Corowa (26,000 sows). PigPulse calculates the historical seasonal cyclical effect, a de-seasonalised trend line and the weekly data of the whole population. The figure illustrates a number of points. Firstly, there is a seasonal cycle in which litter size increases in the June quarter each year and decreases in the December quarter. The Sel-Plex/BioPlex Fe was introduced in the matings starting in February 1999, hence farrowing in June. The weekly weighted average data are well above the seasonal cycle line for the June 1999 quarter, and the December 1999 quarter. In other words, we are observing a better litter size than we expected given the seasonal pattern over the last three years. This is highlighted in the de-seasonalised trend line, which is going up.




Figure 1. The litter size born alive from a population of 26,000 sows at BMI, Corowa. (Marbles indicate data as weekly averages; box line is the quarterly seasonal cycle with a forecast seasonal cycle; smooth line is the de-seasonalised trend line).


IMPROVING PIG MEAT QUALITY

The other avenue of increasing the return from pork is differentiation from other pork products on the market. This can be achieved through the development of niche markets and products or simply by providing a product superior in quality.

Quality is a very broad term and has different meanings dependant upon where in the food chain the term is used. It can mean the fat cover on the pig or it can mean the eating quality of the pork as determined by the consumer. The consumer is the ultimate evaluator of quality; and analysis of consumer requirements is paramount to improving quality and in the end, prices received for the product.

Animal nutrition research is playing a large role in the development of niche markets for nutritionally enhanced pork. Some of the nutritional enhancements currently undergoing development include changes in the fatty acid composition of the pork to improve the amount of omega-3 and -6 fatty acids, increased amounts of vitamins and higher content of selenium.

New approaches to nutrition throughout the entire production system will be vital to the development of ‘organic’ pork. A recent study by Hurley and Kliebenstein, Iowa State University in the United States, showed that 62% of people surveyed would pay a premium for pork products with embedded environmental attributes. This figure would likely to be even higher in environmentally-conscious markets such as Japan and parts of western Europe.

The development of Selenpork, currently marketed in Korea, has come from some basic research by Don Mahan (1999) indicating selenium from Sel-Plex was incorporated into muscle tissue at a linear rate as compared to inorganic selenium, where selenium increased only marginally (Figure 2). This increase in a trace mineral critical to and often limiting in human nutrition makes it possible to differentiate pork reared using organic selenium as a functional food.

New nutrition research will also play a major role in improving the quality of pork through extension of shelf life with nutrients such as vitamin E and organic selenium. Work with vitamin E has shown mixed results in experiments reported in the literature examining antioxidant and shelf life characteristics of pig meat. It is possible that greater understanding of the interaction between vitamin E and selenium forms in the diet may lead to ways of improving meat shelf life. This would be a valuable asset given the time and distance factors involved in modern pork marketing; and work at Bunge is slated to begin in this area very soon.

An exciting area of research involving the use of Bioplex Magnesium to improve the water holding capacity of meat has enormous potential for operations where stock are moved significant distances before slaughter. Reductions in incidence of PSE carcasses are of particular interest in the industry (see D’Souza, this volume). Results at this stage are encouraging and further work is planned in this area.




Figure 2. Effect of selenium source and level on loin selenium content in grower pigs (Mahan, 1999).


ENVIRONMENTAL SUSTAINABILITY

There are very few studies conducted on the trace mineral excretion of animals as there has been no significant environmental pressure to examine this issue until recently. The expansion of the new housing facilities within Bunge Meat Industries has lead to new systems for the disposal of effluent.

These disposal systems are designed with an awareness of the trace mineral profile of the effluent; and thus manipulating this area can improve the return that we receive for the effluent. Table 3 shows results of a study conducted at Bunge Meat Industries in 1999 indicating reduction in trace mineral excretion through use of organic minerals. The concept of ‘environmental nutrition’ via the holistic approach is a very important frontier in nutritional management and research. There is increasing pressure on all livestock operations to become sustainable both economically and environmentally, and the successful accomplishment of both goals is the only way to ensure our survival into the future.


Table 3. Fecal copper content of growing pigs fed diets containing different levels and sources of copper.



The way forward

The responses to organic minerals are no longer a matter of doubt due to the large body of evidence in both controlled research and commercial performance studies. The question that now must be asked is how do we get maximum benefits from these products? More specific knowledge of how the organic mineral forms are absorbed and metabolized will allow the nutritionist to better target their use. The interactions between minerals that occur during digestion will change when we use organic minerals; and we need to understand these interactions to allow us to determine the optimum levels of supplementation. The bottom line is that organic mineral forms will become the normal mode of supplementation; and it remains for researchers and producers to determine the most cost-effective means of application.


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Author: DAVID HENMAN
Bunge Meat Industries, Corowa, New South Wales, Australia