The essence of mineral nutrition for ducks

Proper nutrition schemes are essential for ducks to thrive under commercial conditions. In this respect, trace minerals play an important role for the development of physiological functions such as feathering, bone development and immunity. Organic minerals have the potential benefit of improving mineral utilisation whilst reducing their excretion.

By Zöe Stevenson, Alltech European Bioscience Research Centre, Dunboyne, Ireland

Most of the research on mineral requirements for livestock species was carried out between 1960 and 1980. It is this data that is used by the National Research Council (NRC). It is only recently that these have started to be redefined. Many of the early basic nutrient metabolism studies were conducted in chicks and then related to other livestock species, including ducks. Since then research has focused more on the role of trace minerals in immune function and related physiological mechanisms. The innovation of organic sources of minerals has started to challenge the supplementation of high levels of inorganic minerals in diets for poultry by demonstrating the increased availability of products, such as Alltech’s Bioplex® organic trace mineral range and Sel-Plex®, organic selenium based on a specific strain of Saccharomyces cerevisiae CNCM I-3060.

Mineral inclusions, as with most parts of the diet specifications for ducks, are decided based on requirements for broilers, as specific data rarely exists. Ducks require trace minerals for the same physiological functions as chickens, including antioxidant protection, feathering, bone development and immunity. Optimal mineral nutrition is required for duck production as for all poultry, and the form of the minerals supplied will affect efficiency.

Organic versus inorganic

Previously the most common forms of trace minerals included in diets for poultry were inorganic, including salts such as chlorides, sulfates, carbonates and oxides. During recent years organic trace minerals have become more commonly used in supplements. This is because many university and commercial trials have shown the beneficial effect of organic trace minerals on both the health and performance of poultry.

These mineral proteinates are defined as a mineral that is bound to an amino acid or peptide. Research has indicated that these inorganic sources are more bio-available than inorganic salts for three main reasons:
– The structure protects the mineral from unwanted chemical reactions in the gut.
– They are absorbed more efficiently in the gut and utilised by physiological processes.
– Because they are not charged, there are fewer negative mineral interactions. Birds naturally obtain their minerals from the leaves and grains they ingest. In plants, these minerals are bound to small peptides. In this form they are preferentially taken up in the gut via the same systems that absorb amino acids. In contrast, inorganic minerals are far less bio-available and are excreted at a much higher rate.

New pollution regulations

The resurgence of interest in mineral nutrition is partly due to concerns for the environment and particularly the level of all nutrients in manure. Whilst the current focus is on reducing the amount of nitrogen and phosphorus is released into the environment from animal production, it follows that the level of other components in manure, particularly the heavy metals copper and zinc, will come under the legislative spotlight.

Increasing concerns within the EU regarding the level of soil and water pollution from intensive agriculture have led to discussions and restrictions regarding the supplementation of poultry diets with inorganic minerals. The use of lower levels of minerals in an organic Bioplex form is known to reduce mineral excretion whilst maintaining performance in poultry, due to their increased availability. Mineral availability and excretion is important to all producers, including those growing ducks, as new pollution legislation comes into force.

Recent trial work

In light of research with organic minerals in other poultry species, the aim was to compare the performance of ducks fed a commercial inorganic mineral premix with one containing Sel-Plex and Bioplex Copper (Cu), Zinc (Zn), Manganese (Mn) and Iron (Fe). Bioplex minerals were added to the trial supplement at lower levels than the inorganic forms included in the standard supplement (Table 1) and Sel-Plex was added to provide 0.3 ppm in the starter and 0.25 ppm in the grower feed. In response to interest in reducing the mineral output from poultry units, faecal excretion of copper, zinc and manganese was also monitored on a weekly basis. The trial was carried out in collaboration with Cherry Valley and took place at their research unit, using mixed sex Pekin (SM3H) ducks. The unit was split into 16 rooms, each of which housed 100 ducks. Treatments were randomly assigned to each of the rooms. The ducks were fed a commercial wheat-based ration, only differing in the mineral sources used in the supplement.

The birds were grown under commercial management practises for 46 days and the following parameters measured: live weight and feed intake per pen on a weekly basis from which FCR was calculated. Mortality was recorded daily per pen and all results were statistically analysed using ANOVA. Faecal samples were collected by placing a piece of plastic of 0.5 m2in each pen for 24 hours, each week.

Significant interest

The performance of the ducks was very good, meeting or exceeding breed standards:
• No significant differences were found between treatments on duck performance at 45 days of age (Table 2).
•Performance was maintained in group B despite reduced mineral intake, indicating that Bioplex organic trace minerals are more available and better utilised by the ducks.
• Ducks fed Bioplex organic trace minerals excreted, on average, 45% less minerals than those fed an inorganic supplement, potentially significantly reducing mineral pollution from duck production (Figure 1).
• There were no observable differences in feathering.

The results of this pen trial were of significant interest to Cherry Valley. They decided to replicate the study in commercial units over two cycles. In each case the same sheds were used: two fed a standard supplement containing inorganic minerals and one fed a supplement containing Bioplex Copper, Zinc, Manganese, Copper and Iron along with Sel-Plex. The levels of minerals included as Bioplex were the same as those used for the pen trial, between 48 and 30% of the inorganic levels included in the standard premix. The performance results are summarised in Table 3. It can be concluded that there were no significant differences in the performance of the birds in the trial shed despite the reduction in addition of copper, zinc, manganese and iron.

Maintain performance

Using the same method as in the pen trial, in the first of these trials faecal samples were collected at 35 and 42 days and analysed for mineral content. The results are summarised in Table 4 and show a reduction in mineral excretion in a commercial situation as was seen in the pen trial.

This series of trials shows that it is possible to feed lower levels of minerals in an organic form and maintain the performance of ducks whilst reducing the levels of minerals excreted in the faeces. Forthcoming EU pollution regulations will limit the level of minerals in manure and control the amount that can be spread on land, in order to reduce issues of run-off into water courses. Therefore, poultry producers need to address the levels of minerals they are adding to diets and the levels excreted by birds. Mineral specifications of premixes for ducks can be reduced by total replacement with Bioplex organic trace minerals and Sel-Plex, which are more available and better utilised by birds.

The future for ducks

Due to increased legislative pressure it is likely that the innovation of organic mineral nutrition will be a necessity in all animal production, including ducks. Despite commercial trends towards higher feed inclusion rates of essential trace elements, the legislative response is likely to limit supplementation. New mineral recommendations based on the increased availability of these natural mineral forms will have the potential to reduce pollution from intensive poultry farms. This effect is backed by a wealth of research in broilers and laying hens, with an increasing amount carried out in turkeys and ducks. It has been clearly demonstrated that when lower levels of organic minerals are fed, performance can be maintained, whilst improving other aspects of health and welfare.

World Poultry Vol. 25 No. 4 2009