Research finds that adding hydroxy trace minerals to feed can reduce mortality and improve performance comparable to an ionophore when addressing necrotic enteritis.
Necrotic enteritis (NE) is the most common Clostridial enteric disease in the poultry industry today. The cost to the industry is more than US$ 2 billion dollars annually. It is a disease characterised by necrosis and inflammation of the gastrointestinal tract, a significant decline in growth and performance, and increased mortality. The bacteria responsible for NE ‒ Clostridium perfringens ‒ is prevalent everywhere; dirty litter, excreta, soil, dust, and even healthy bird intestines. C. perfringens bacteria produce toxins that result in the small intestinal damage, lesions, and mortality seen in NE. Coccidiosis is often a concurrent problem associated with NE outbreaks, and because its presence is generally required to see full-blown NE, prevention of cocci is key in keeping flocks healthy.
The photo's show intestines affected by late-stage necrotic enteritis of heavily diseased broilers. Photo: Terri Parr
Typical tools available to the producer to maintain flock health have generally included antibiotics, ionophores, and vaccines. With the implementation of the Veterinary Feed Directive on 1 January 2017, along with the increase of antibiotic-free diets, there is a great deal of concern that the US will see a resurgence of NE as was seen in the European Union when antibiotics were banned. Therefore, there needs to be a focus on 3 strategic areas of prevention to reduce NE:
- enhance the immune system;
- reduce pathogens; and
- incorporate dietary modifications and/or feed additives that can help minimise the performance impact of NE.
Range of measures
The execution of the first 2 preventive measures mentioned above tend to fall more in the hands of veterinarians and live production managers, with regard to keeping birds vaccinated and the facilities as clean as possible. The third area of focus is often under the direction of nutritionists. The list of additives available to nutritionists today is quite extensive. Some more commonly used options include prebiotics/probiotics, organic acids, botanicals, yeast components and essential oils. While this list is not intended to be all-encompassing, one option for increasing bird health is notably absent – minerals.
Minerals can be a bit confusing in their own right, as many different mineral sources are available. Traditionally, inorganic sulphates and oxides were the minerals of choice – in more recent years, the use of organic (chelated) minerals has increased. While organic minerals have demonstrated superior performance compared to sulphates and oxides, the cost of using organics as a complete mineral source is often prohibitive. A newer class of minerals – hydroxy trace minerals (hydroxychlorides) – also elicit a superior response from birds. This class of trace minerals combines the stability of bond strength with a large and stable crystalline structure. Compared to sulphates, they have a stronger bond that holds the mineral (copper, zinc, or manganese) to the chlorides and hydroxy groups. Typically, a sulphate mineral begins to dissolve immediately upon exposure to moisture – whether in the feed or in the bird. Therefore, most sulphates dissolve very quickly in the upper GI tract, becoming rapidly bound by charged particles. When compared to organic minerals, hydroxy minerals have multiple mineral ions connected in a crystal matrix, instead of just one mineral atom connected to a ligand or amino acid. Although the metals in the outer layers are slowly reacting as the crystal moves through the GIT, there are more metals remaining in what is a relatively massive crystal matrix – allowing more mineral to be present and available throughout the length of the digestive tract.
Photos: Terri Parr
Hydroxy mineral trials
Research conducted by Klasing et al., demonstrated an improved ability of hydroxy minerals to decrease the proliferation of E. coli and C. perfringens in bird gastrointestinal tracts in comparison to sulphates. With this knowledge in hand, additional trials were conducted to see how the performance might be maintained in spite of C. perfringens being present during true NE outbreaks.
Figure 1 – Feed conversion of birds fed various levels and sources of copper in a necrotic enteritis challenge (P<0.05). when copper from hydroxychloride was increased to 200 ppm, fcr was equal to birds that received an ionophore (72 g t).
In the first trial, inorganic oxides and sulphates were fed as the copper and zinc sources to Cobb 500 males. All birds were first given a coccidiosis vaccine, then challenged with necrotic enteritis. Copper was fed to all birds at either 125 or 200 ppm. Zinc was included at three levels in addition to each copper level. Zinc had little impact on performance in addition to copper, and thus will not be discussed in this article. Weight gain of birds fed 125 ppm of copper – the typical inclusion rate seen in the US for the first 28 days of a bird’s life – was no different regardless of source (Figure 1). But when copper hydroxychloride was increased to 200 ppm, body weight and the feed conversion rate (FCR) were equal to birds that received an ionophore (Narasin and Nicarbazin, 72 g/t). Mortality decreased by 36% when 200 ppm of copper hydroxychloride was fed (Figure 2), although the mortality level was still not as low as the birds given an ionophore.
Figure 2 – Mortality rate of broilers fed various levels and sources of copper in a necrotic enteritis challenge (P<0.05). birds receiving feed with 200 ppm copper hydroxychloride experienced a 36% decrease in mortality.
A second trial was initiated in an attempt to maintain mortality below 10% ‒ a more realistic level if a commercial facility were to experience a necrotic enteritis outbreak. It was also an opportunity to increase the copper level further in an attempt to effect a more robust change in the performance of NE-challenged birds. Birds were vaccinated for coccidiosis at day one of age, then challenged with necrotic enteritis at day 17. All minerals in the trial were hydroxychlorides. Copper was included at 125 ppm in the controls, then fed at 3 additional levels – 175, 225, and 275 ppm. Results indicated that the higher the copper level fed, the better the FCR and mortality of the challenged birds (Figures 3 & 4). At 225 ppm copper, birds displayed a feed conversion and mortality equal to the control birds fed an ionophore (72 g/t).
Figure 3 – Feed conversion (0-28d) of broilers fed various levels of copper hydroxychloride during a necrotic enteritis challenge (P<0.0001). birds receiving 275 ppm of copper hydroxychloride in their feed experienced feed conversion levels similar to birds receiving an ionophore.
Figure 4 – Mortality (17-28d) of broilers fed various levels of copper hydroxychloride during a necrotic enteritis challenge (P<0.0009). birds receiving 275 ppm of copper hydroxychloride in their feed experienced mortality levels similar to birds receiving an ionophore.
While the inclusion of higher levels of copper hydroxychloride seems like a simple fix, extreme caution must be employed when source is selected. Copper hydroxychloride has been fed up to 450 ppm with no detrimental effects on performance, but feeding similar levels of inorganic copper sulphate have been shown to result in a depression of feed intake and average daily gain (Luo et al., 2005; Figure 5). Therefore it is imperative to understand the limits of mineral source on bird performance.
Figure 5 – Comparing growth parameters in birds fed copper sulfate minerals compared to copper hydroxychloride shows higher levels of the sulfate resulted in depressed weight gain and average daily gain.
As producers look for options to maintain animal performance in response to ever-increasing restrictive regulations, copper hydroxychloride appears to be a strong contender for that space. It is a product held in the majority of producers’ inventories, and is often used on a daily basis. Proactive formulation of the higher levels of copper can result in improved weight gain and FCR during the incidence of a necrotic enteritis outbreak. Increasing inclusion of a quality copper, such as copper hydroxychloride, can significantly reduce flock mortality and mitigate the performance effects of necrotic enteritis during a challenge, thus allowing birds to grow comparably to birds fed an ionophore.
References available upon request.