Nivalenol originates principally from cereal grains, and may be present in the by-products produced as a result of processing. Cereal grains and their by-products are widely used in feeds for livestock. In 2011, European feed manufacturers produced over 151 million tonnes of compound feed of which almost half (48 %) was cereal grains. In addition, over 17 million tonnes of by-products from the food industry – principally cereal by-products – were used (FEFAC, 2012).
In addition to cereals and cereal by-products, other feeds include oilseed meals (28 %), pulses, dried forages, dairy products, minerals, vitamins and additives (FEFAC, 2010).
Mycotoxin-producing Fusarium species can infect other growing crops, including grass, hay and straw, all of which are sources of animal fodder and silage. When directly consumed by animals these forage crops could give rise to mycotoxicosis (Scudamore and Livesey, 1998). In silage, however,
Fusarium species are not major contaminants because most are aerobic and are unable to grow under
the anaerobic conditions used in silage making (Scudamore and Livesey, 1998).
There is considerable variation in both the feeds used and the feeding systems adopted throughout Europe for farm livestock, companion animals and fish. This variation is largely due to the availability of feeds and market demands for specific animal products. The amount of feed consumed is also closely linked to its digestibility and the levels of activity or production of the animal.
Exposure to nivalenol (Section 6.2) requires estimates of feed intake. Estimates of intake by farm livestock, companion animals and fish are given in Appendix B. It should be stressed that they do not represent ‘average’ diets, nor are the feeding systems ‘typical’ for all of Europe. Instead, they are used to estimate levels of exposure to nivalenol toxins that might not be atypical. They are based on published guidelines on nutrition and feeding (e.g. AFRC, 1993; Carabano and Piquer, 1998; NRC, 2007a,b; Leeson and Summers, 2008; EFSA, 2009a; OECD, 2009; McDonald et al., 2011), data on EU manufacture of compound feeds (FEFAC, 2009) and expert knowledge of production systems in Europe. In the absence of sufficient occurrence data for individual types of feed, exposure to nivalenol has been calculated using the data for the category ‘cereal grains, their products and by-products’. 5.2.1. Dairy cows
In common with other ruminants, forages – either fresh or conserved – represent the main feed for dairy cows, and typically account for between 60 and 100 % of daily dry matter intake (AFRC, 1993), depending on the level of production and the quality of the forage. They are predominantly grasses and legumes, but whole-crop maize and cereals are also fed after ensiling. Forages are supplemented with commercial compounds or other non-forage feeds in those situations where the forages on their own do not provide the necessary nutrients to meet the animals’ requirements. The amounts of non- forage feed given are adjusted according to the amount and quality of the forage available and the milk yield of the cow, and adjusted for pregnancy and live weight gain, but will typically be about 0.25 - 0.35 kg feed/kg milk production (Nix, 2010).
Cereal grains are an important constituent of dairy cow diets. In Northern Europe, barley and wheat are most commonly used, while in Southern Europe maize (corn) is more widely used. The actual amounts used can vary considerably, depending on their price and the availability of other feeds, but levels of up to 30 % of total dry matter intake are not uncommon. Because of their lower energy content relative to other cereals, oats are less widely used in diets for dairy cows.
For this Scientific Opinion, exposure is estimated for a 650 kg dairy cow, with a milk yield of 40 kg/day. In addition, exposure has been calculated for dairy cows (milk production 30,40 and 50 kg/day) fed a diet based on maize silage and variable compound feeding rates of 0.28, 0.30 and 0.32 kg/kg of milk (equivalent to 8.4, 12 and 16 kg/day of non-forage feed intake). Assumptions on the proportions of forages and non-forage feed, and the proportions of cereal grains, their products and by-products in the non-forage component of the diet, are given in Appendix B, Tables B1, B4 and B5.
5.2.2. Beef cattle
There is a wide variety of beef production and husbandry systems in Europe. They may be categorised broadly as pasture-based and cereal-based systems, although combinations of these systems are commonly found. They aim to produce animals for slaughter from less than 8-months of age (veal production), to 12 month ‘cereal beef’ or for slaughtering at up to 24 months of age (or more).
For many beef cattle, forages represent the major - and often only - ingredient in their diets. The forage may be fed fresh (i.e. grazed) or conserved as silage, hay or cereal straws to be fed when fresh forage is not available. The amount of forage consumed is determined by a number of factors, including the age/size of the animal, forage digestibility, the quality of the fermentation (when ensiled) and the availability of other feeds.
Other non-forage feeds, including cereals and vegetable proteins, are given when forages alone, because of their quality or availability, do not provide sufficient nutrients to achieve intended growth rates.
For the exposure estimates for forage-based beef production, the CONTAM Panel assumed a live weight of fattening (beef) cattle of 400 kg and a daily intake 9.6 kg dry matter (1.4 kg dry matter/day of non-forage feeds) for the cattle fed grass silage and non-forage feeds. Maize silage-based rations generally have higher intakes than grass silage, and an intake of 9.5 kg dry matter/day forage and 1.0 kg dry matter/day of non-forage feeds has been assumed by the CONTAM Panel based on Browne et al. (2004). Assumptions on the proportions of forages and non-forage feed, and the proportions of cereal grains, their products and by-products in the non-forage component of the diet, are given in Appendix B, Tables B1 and B4.
In contrast, intensive cereal-based systems of beef production provide diets that consist almost entirely of rolled cereal grains, supplemented with vegetable proteins (McDonald et al., 2011). In this system of production, high levels of daily gain may be achieved, and feed intake may be as high as 2.5 % of body weight (NRC, 2000). In this Scientific Opinion, it has been assumed that, a 400 kg bull consumes 8.4 kg of dry matter feed per day (AFRC, 1993), of which 85 % is non-forage feed containing 75 % cereal grains, their products and by-products (Appendix B, Tables B1 and B4).
5.2.3. Sheep and goats
Domestic sheep and goats are primarily raised for the production of meat, milk or wool. As a result, a large number of breeds and systems of management have been developed to suit the land, climate and husbandry conditions in the EU. As for other ruminants, good quality forage is the most important dietary ingredient and for many of these livestock forages may be the only feeds used after weaning (NRC, 2007a). Exceptions to this are:
Pregnant and lactating animals: supplementation with non-forage feeds or commercial compound feeds usually occurs in late pregnancy, up to a maximum of 2.5 kg/day, and often continues into lactation, depending on the quality and availability of forages, and the number of lambs or kids produced (AFRC, 1993; NRC, 2007a). They usually consist of cereals, cereal by-products and vegetable proteins supplemented with minerals and vitamins (McDonald et al., 2011).
For lambs and kids: some compound feeds may be given around the time of weaning to encourage the intake of solid feed. The amounts consumed are generally small, particularly if there is forage available.
Sheep and goats reared for meat production: diets consist predominantly of forage, with additional feeds given to achieve levels of live weight gain required. Total daily dry matter intakes can range from 1.9-3.8 % of their body weight (Devendra and Burns, 1983), of which forages typically account for 75 % or more of total intake. In commercial practice, goats reared for meat production and with a
body weight > 10 kg are often fed green fodder ad libitum (AFRC, 1993) supplemented with cereal grains (barley, oats or maize), cereal by-products and vegetable proteins (McDonald et al., 2011). Milking sheep and goats: compound feeding usually commences in late pregnancy and continues into lactation. For an 80 kg lactating ewe, compound or other non-forage feeds may be fed at a flat rate of 1.0-1.3 kg/day for the first 60-70 days of lactation, reducing to 0.9 to 1.0 kg/day for the next 60 days, and 0.5 kg/day in late lactation (AFRC, 1993). Due to physiological and metabolic differences, goats are able to consume diets with higher proportions of non-forage feeds without adversely affecting feed intake or production (Avondo et al., 2008). The actual amounts depend on the quality of the forage available. Non-lactating animals usually receive only forage feeds.
The CONTAM Panel has used a daily dry matter intake of 2.8 kg for an 80 kg lactating sheep feeding twin lambs to estimate the exposure to nivalenol. For a 60 kg milking goat producing 6 kg milk/day, a daily feed intake of 3.4 kg dry matter per day has been assumed.
The dry matter intakes of goats reared for meat and fed ad libitum can be as high as 3.8 % of body weight (Devendra and Burns, 1983). The CONTAM Panel has used a daily dry matter intake of 1.5 kg for a 40 kg goat for fattening to estimate the exposures to nivalenol. For all categories of sheep and goats, the proportions of cereal grains, their products and by-products in the non-forage feeds are given in Appendix B, Table B4.
5.2.4. Pigs
There is a considerable range of pig production systems and diets fed to pigs in Europe. A common feature is that diets for fattening pigs and sows consist predominantly of cereals and cereal by- products, supplemented with vegetable proteins (e.g. soybean meal, peas and beans, rapeseed meal). For breeding pigs, the relative proportions of these ingredients in the diets will be different during pregnancy and lactation. Diets for breeding pigs also tend to include greater proportions of fibrous feeds such as cereal by-products and sugar beet pulp (McDonald et al., 2011).
Exposure estimates have been made for piglets (20 kg b.w.), fattening pigs (100 kg b.w.) and lactating sows (200 kg b.w.) using feed intakes proposed by EFSA (2009a). The proportions of cereal grains, their products and by-products used in estimating the exposure for pigs are given in Appendix B, Table B6.
5.2.5. Poultry
Poultry have limited ability to digest fibre18, and therefore cereal grains form the major part of their diets. In Europe, wheat, maize and barley are most commonly used, with rye, sorghum triticale and oats used less widely. Other ingredients include cereal by-products and vegetable proteins, supplemented with minerals, trace elements and vitamins (Leeson and Summers, 2008; McDonald et al., 2011).
The amount of feed consumed is largely determined by the size and age of the bird. Under ad libitum feeding, daily intake increases as the birds get older, although relative to body weight it declines with age. For meat producing and egg laying birds, ad libitum feeding is widely practiced, but for breeding stock feed intake is frequently restricted to maintain a steady body weight (Leeson and Summers, 2008).
The CONTAM Panel applied the live weights and feed intakes reported for different poultry (broilers, laying hens and turkeys) by EFSA (2009a) and for ducks by Leeson and Summers (2008) for the exposure estimations. The proportions of cereal grains, their products and by-products used in estimating the exposure for poultry are given in Appendix B, Table B6.
5.2.6. Rabbits
Commercial rabbit production takes place in at least 14 EU member states, including the Czech Republic, Slovakia, Poland and Hungary. The largest producers are Italy, France and Spain. The EU is responsible for about 0.5 million tonnes, representing 55 % of world rabbit meat production19.
Young rabbits are normally kept with the mother to around 4-5 weeks old, then moved to a fattening cage, until 10-12 weeks old before slaughter at about 2 kg b.w.19
Rabbits are usually fed a pelleted diet of dried forages, cereals and vegetable proteins supplemented with minerals, vitamins and trace elements. Lebas and Renouf (2009) reviewed diet formulations used in experimental studies: in 58 diets, cereals and cereal by-products (mostly wheat bran) accounted for up to 40 % of all ingredients. In these studies, maize was a major cereal grain and was included in more than one-third of all diets. In northern Europe, however, maize may be replaced by barley and wheat. Feed intakes of 65-80 g/kg b.w. have been reported (Carabano and Piquer, 1998).
For the exposure estimates, the CONTAM Panel assumed a live weight of 2 kg, and a feed intake of 75 g/kg b.w. The proportions of cereal grains, their products and by-products used in estimating the exposure are given in Appendix B, Section B2.3.
5.2.7. Farmed fish
Atlantic salmon is economically the most important farmed fish in Europe, although other commercially reared species include rainbow trout, sea bass, sea bream, cod, halibut, tuna, eel and turbot. Given the wide range of species and environmental conditions for farmed fish, many different feeding strategies have been developed. However, given its predominance in EU aquaculture, feed intake and exposure to nivalenol toxins have been estimated for salmon in this Scientific Opinion. Traditionally, the principal raw materials used for the manufacture of fish feeds in Europe have been fish meals and fish oils, and although alternative sources of oil and protein (e.g. soybean meals and vegetable oils) are increasingly being used fish-derived feeds still remain the major ingredients. Since cold-water fish do not utilize carbohydrates as energy sources as efficiently as warm-water species, there is less use of cereals. Berntssen et al. (2010) provided details of the composition of a diet for growing Salmonids, and the CONTAM Panel used these to estimate exposure to nivalenol toxins for salmon (2 kg) with a feed intake of 0.04 kg dry matter/day (EFSA, 2009a). The proportions of cereal grains, their products and by-products used in estimating the exposure are given in Appendix B, Section B2.4.
5.2.8. Horses
Horses are complete herbivores. They will generally consume 2-3.5 % of their body weight in feed (dry matter) each day, of which a minimum of 50 % should be as forage (pasture or hay) (NRC, 2007b). Mature horses with minimal activity can be fed forage alone, but for growing and active horses supplementary feeding with cereal grains, cereal by-products (e.g. oats, barley, and wheat bran) and vegetable proteins is necessary. Although oats are the preferred cereal for many horse owners, other cereal grains and cereal by-products are also routinely used. The CONTAM Panel estimated the exposure for a 450 kg horse, with a daily intake of 9 kg dry matter/day, of which half is in the form of forages and where cereal grains, their products and by-products represent 75 % of the non-forage component of the daily ration (Appendix B, Section B2.5).
5.2.9. Feed consumption by companion animals (dogs and cats)
Most small companion animals derive their nutritional needs from processed food, and in 2010 EU annual sales of pet food products was approximately 8.3 million tonnes20. Although a wide range of
19 Source: http://faostat.fao.org 20 www.Fedif.org
ingredients is used in commercial diets, most dog and cat diets contain at least some animal protein. Other ingredients include cereals (predominantly wheat, rice or maize), cereal by-products, vegetable proteins and by-products of human food production.
Many pet food manufacturers produce standard and premium quality brands for dogs and cats. While both normally contain some cereals, levels tend to be higher in the standard brands, and may be as high as 65 %21. Dog food also tends to contain more cereals than cat food (J.M. Fremy, 2011, personal communication). In the absence of any general information on ingredients used in dog and cat food in the EU, data from France21 have been used in this Scientific Opinion to estimate exposure to nivalenol by cats and dogs. These values, together with estimates of intake (Appendix B, Section B1.5) should be regarded as being indicative only, and will vary depending both on the availability of feed materials and on the nutrient requirements of the animals. The proportions of cereal grains, their products and by-products used in estimating the exposure are given in Appendix B, Section B2.6.
The amounts of food consumed by dogs and cats are influenced by many factors, including breed, size, level of activity and their reproductive state. In this Scientific Opinion the CONTAM Panel has assumed a live weight 4 kg and feed intake 60 g/day of standard pet food quality for cats (Appendix B, Section B1.5). For the dogs, it has assumed a live weight 25 kg and feed intake of 360 g/day of standard quality (Appendix B, Section B1.5.).
6. Exposure assessment of nivalenol in humans and animals