Proposal – Maximum Nutrient Values in Rabbit Feeds

July 2018

Purpose

As part of a comprehensive, multi-year regulatory modernization process, the Canadian Food Inspection Agency (CFIA) has initiated the renewal of the federal Feeds Regulations (Regulations) as one of several priorities identified for modernization.

The goal of renewing the Regulations is to develop a modernized risk- and outcome- based regulatory framework for feeds which:

• safeguards feeds and the food production continuum
• attains the most effective and efficient balance between fair and competitive trade in the market
• minimizes regulatory burden

Modernization of the Regulations provides the opportunity to review feed controls, standards, labelling and other regulatory requirements. The purpose of this proposal is to:

• review the nutrient content standards for rabbit feeds set out in Table 4 of Schedule I of the current Regulations which the CFIA has used to exempt complete feeds and some supplements from registration
• recommend possible updates or amendments to the current requirements

Background and current situation

Table 4 of Schedule I was created and incorporated into the Feeds Regulations in the 1980s as a mechanism to exempt certain groups of feeds from mandatory registration. The original Table 4 established nutrient ranges (minimums and maximums) as exemption criteria for feeds for chickens, turkeys, swine, beef and dairy cattle, and sheep. In 1990, via two regulatory amendments, the table was first expanded to include horses, goats, ducks, and geese; and then for rabbits, mink, and salmonid fish. Since that time, there have been no other substantive changes to the table or to any of the nutrient ranges.

Currently, the feed can be exempted from registration if:

• a complete feed provides nutrients which fall within the ranges listed in Table 4 or
• a supplement has directions for use which would result in a complete feed that provides nutrients which fall within the Table 4 ranges

Feeds that provide nutrients which fall outside the ranges listed in Table 4, and that do not meet any additional exemption criteria, require assessment and registration by the CFIA prior to manufacture and sale. However, complete feeds intended for feeding to livestock not intended for human consumption and which are in packages up to 5 kg are exempt from any requirements of the Feeds Act and Regulations altogether.

As indicated in the 2016 Feed Regulatory Renewal Consolidated Modernized Framework Proposal, both the CFIA and stakeholders recognize that some of the values in Table 4 may no longer have the same nutritional relevancy that they did when the table was first introduced. Stakeholders have also indicated that they feel that Table 4 prevents innovation for new feed products. However, many of the maximum nutrient levels which are currently set out in Table 4 have health and safety implications that must be considered.

Proposal

It is proposed that:

• Table 4 be removed from the Regulations and no longer serve as a trigger to register feeds based on specified ranges of nutrient content
• maximum nutrient levels be established and incorporated by reference for rabbit feeds
• the proposed maximums are established based on total daily diets rather than for complete feeds only

This proposed approach addresses stakeholder concerns regarding Table 4 and its relevance in current industry practices, as well as claims that the nutrient ranges provided in Table 4 impede new products from entering the marketplace. Furthermore, it addresses concerns regarding the harmful impact that higher levels of certain nutrients may have on livestock or the resulting food products, and underscores the modernized regulatory framework's focus on health and safety for humans, animals, and the environment. It is further proposed that:

• minimum levels for nutrients will no longer be established in the Regulations, however feeds will still be required to be suitable for their intended purpose and must meet an animal's nutritional requirements
• maximum levels for nutrients will be established by species or classes of species, as appropriate
• nutrient maximum levels will be incorporated by reference in the Feeds Regulations to facilitate updating, as necessary
• the exemption for complete feeds intended for animals not intended as food for human consumption will be raised to packages containing up to 10 kg.

Considerations

The domestic feed industry considers that the Table 4 nutrient ranges are out of date, and that this table is no longer an appropriate regulatory tool for feeds. However, there remains a continued need for an enforceable regulatory framework regarding maximum nutrient concentrations in livestock feeds for health and safety reasons. For instance, levels of certain vitamins in livestock rations (for example, vitamins A, D, and E) in excess of nutritional requirements can be harmful to livestock or can be concentrated into tissues that are used for human consumption, thus posing potential risk to human health. Similarly, certain minerals (for example, copper, iodine, phosphorus and zinc) fed in excess of livestock requirements can also contribute to increased human and environmental risks.

A significant proportion of minerals fed in excess of requirements are excreted into the environment via urine and feces. Consequently, even though the maximum tolerable level (MTL) of a given mineral may be significantly greater than the nutritional level, feeding at the maximum tolerable level may result in negative impact on the environment.

An analysis of rabbit nutritional requirements and maximum tolerable dietary nutrient levels was conducted by the CFIA with the following scope:

• to determine those nutrient levels that may impact the health and safety of the respective livestock, humans, and environment
• to determine those nutrient levels that support a nutritional purpose as opposed to a therapeutic purpose
• to determine those nutrient levels that may produce residues in the resulting food that could be harmful to those consuming the products

Information sources used in the review and development of nutrient maximums in rabbit feeds included:

• recommendations and formal opinions provided by other national authorities and food safety agencies (for example, the National Research Council of the National Academies, the European Food Safety Authority)
• research published in peer-reviewed literature (for example, the Journal of Animal Science, Journal of Nutrition)
• Guidance document on classification of veterinary drugs and livestock feeds

The Appendix in this proposal sets out the proposed maximum nutrient values for rabbit feeds.

The current Table 4 nutrient values to exempt feeds from registration are for the complete feed (grain portion of diets only) on an "as fed" basis (assumed 90% dry matter), assuming a fixed intake for rabbits. In contrast, the proposed maximum nutrient levels are to be applied to the total dietary intake. These proposed maximums were derived taking into consideration typical total daily diets for rabbits and ranges for nutrient content of the forages (where known) as well as complete feeds (grain portion) and are reported on a "dry matter" basis. The proposed maximum nutrient concentration in the daily diet has been set high enough to provide flexibility to formulate nutritionally and environmentally sound diets.

While the NRC requirements for vitamins are on a supplemental basis and the maximum values indicated in this proposal are on a total diet DM basis, the proposed values are over and above the NRC requirements such that contributions from the grain and forages, though variable, would not result in values exceeding the stated maximums.

Notes on some of the considerations incorporated into setting the maximum value are provided at the bottom of the tables for each nutrient in the Appendix.

Anticipated outcomes

This proposed, modernized regulatory approach to the oversight of maximum nutrient content in rabbit feeds would:

• give regulated industry the flexibility to manufacture feeds with nutrient contents that meet their customers' needs without requiring pre-market assessment and authorization
• allow the CFIA to maintain regulatory oversight for hazards that may negatively impact human or animal health or the environment
• allow for timely updates to the standards as new information concerning specific nutrients is provided
• reduce the regulatory burden on industry wishing to get innovative products into the marketplace

Stakeholders are being provided with an opportunity to comment on all proposals, including the maximum nutrient values being suggested for each species or class of species, before they are incorporated into a regulatory framework.

References: A complete bibliography is available upon request

We strongly encourage you to provide your input and feedback, which is critically important to the success of the regulatory modernization initiative.

Please send written comments by 08/17/18 to:

Sergio Tolusso
Canadian Food Inspection Agency
Animal Feed Division
59 Camelot Drive
Ottawa, ON K1A 0Y9

Email: Sergio.tolusso@canada.ca
Fax: 613-773-7565

Appendix – Proposed maximum nutrient values for rabbit feeds

Macro-minerals

Considerations:

• rabbits' dietary calcium (Ca) is absorbed in direct proportion to its concentration in the diet (Halls 2010)
• recommended Ca requirements for rabbits are: 0.4% of diet DM for finishing rabbits, 0.6% of diet DM for growing rabbits, and 1.05% of diet DM for breeding does (Mateos, Rebollar et al. 2010)
• maximum tolerable level of Ca in rabbit feed is 2% of diet DM (NRC 2005)
  • this assumes there is sufficient phosphorus (P) in the diet and a Ca: P ratio <10
• excessive Ca supplementation increases the risk of urolithiasis and calcification of soft tissues in rabbits (Kamphues, Carstensen et al. 1986, Cheeke 1987, Mateos, Rebollar et al. 2010, Clauss, Burger et al. 2012)

Considerations:

• recommended phosphorus (P) requirements for rabbits are: 0.3% of diet DM for finishing rabbits, 0.4% of diet DM for growing rabbits, and 0.6% of diet DM for breeding does (Mateos, Rebollar et al. 2010)
• phosphorus supplied in surplus of dietary needs is excreted in the manure, contaminates runoff water and leads to eutrophication; this is a significant environmental concern (Maertens, Cavani et al. 2005, NRC 2005)
• maximum tolerable level for P in rabbit feed is 1% of diet DM (NRC 2005)
  • this assumes a calcium: phosphorus (Ca:p) ratio of < 10

Considerations:

• most rabbit feeds contain adequate magnesium (Mg) and do not require additional Mg supplementation (Blas and Wiseman 2010)
• published Mg requirements range from 0.03% of diet DM (NRC 1977) to 0.3% of diet DM (Evans, Jebelian et al. 1983, Cheeke 1987, Lebas 2004)
• excessive dietary Mg is excreted in the urine (Blas and Wiseman 2010)

Considerations:

• growing rabbits require 0.22% of diet DM as sodium (Na) and lactating does require 0.25% of diet DM as Na (Lebas 2004)
• 0.24% to 0.40% dietary Na is optimal for growth (Surdeau, Henaff et al. 1973)
• the provision of 0.5% dietary sodium chloride (NaCl) (approximately 0.2% Na) or ad. libitum access to salt blocks are adequate means of providing dietary sodium to rabbits (NRC 1977)
• excessive sodium in feed (and/or water) is detrimental to the growth of rabbits (Harris, Cheeke et al. 1984b, Marai, Habeeb et al. 2005)

Considerations:

• rabbits require 0.6% to 1.0% potassium (K) of diet DM (Hove and Herndon 1955, Blas and Wiseman 2010)
• when potassium is supplied at a level greater than 0.8% of diet DM, there is a greater incidence of nephritis in rabbits (Surdeau, Henaff et al. 1973)
• rabbits fed diets with more than 1.0% K have reduced intakes and decreased performance (Evans, Jebelian et al. 1983)

Considerations:

• most rabbit feeds contain over 0.2% sulfur (S) and are not supplemented with additional S (Mateos, Rebollar et al. 2010)
• a level of 0.25% dietary S is recommended for growing rabbits and lactating does (Lebas 2004)
• there are no reports of supplemental S advancing rabbit performance (Mateos, Rebollar et al. 2010)

Trace minerals

Considerations:

• rabbits require cobalt (Co) for the synthesis of vitamin B12 (Blas and Wiseman 2010)
• reported Co requirements for rabbits vary between 0 and 0.25 mg/kg diet DM (Mateos, Rebollar et al. 2010)
• European Food Safety Authority (EFSA) suggests a maximum content of 1 mg Co/kg diet DM in rabbit feed (EFSA, 2009)
• Co and Co compounds pose a risk to workers during mixing and feeding, due to their dusting potential and presumed carcinogenicity after inhalation (EFSA, 2012; 2009; Agency for Toxic Substances and Disease Registry (ATSDR), 2004)
• excessive cobalt supplementation leads to embryonic toxicity and inhibition of skeletal development (Szakmáry, Ungváry et al. 2001)

Considerations:

• reported copper (Cu) requirements for rabbits vary between 3 and 10 mg/kg diet DM (Blas and Wiseman 2010)
• EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) 2016 reports that copper levels considered safe for animals can result in substantial excretion of copper and a significant environmental load; they propose lowering copper maximums in feed
• use of Cu supplements greatly exceeding requirements in rabbit feed also threatens food safety through the potential emergence and spread of antibiotic resistance pathogens
• although the European Union currently authorizes a maximum content of 25 mg Cu/kg diet in rabbit feeds (European Union Commission 2006), the CFIA is proposing a maximum of 125 mg/kg of total diet DM

Considerations:

• reviews of requirements for iodine (I) in rabbits suggests that 0.2 to 1.1 mg /kg of diet is sufficient to meet animal requirements (Mateos, Rebollar et al. 2010)
• current authorised maximum of iodine in rabbit feed in the European Union is 10 mg I/kg diet (European Union Commission 2004)

Considerations:

• reviews of the requirements for iron (Fe) in rabbits suggests that 30 to 100 mg Fe/kg of diet is sufficient to meet animal requirements (Mateos, Rebollar et al. 2010)
• forages are abundant in Fe; as such, the maximum safety limit is set to accommodate the high intrinsic level that may be present in forages

Considerations:

• requirements for manganese (Mn) in rabbits are reported as 2.5 to 15 mg Mn/kg diet (Mateos, Rebollar et al. 2010)
• current authorised maximum of Mn in feed in the European Union is 150 mg/kg diet (European Union Commission); at this level manganese is considered safe for the animal, worker, consumer, and environment
• excessive Mn supplementation in rabbit diets can lead to anorexia, weight loss and anesthesia and paralysis of the hind extremities (Umarji, Anantanarayanan et al. 1968)

Considerations:

• reported selenium (Se) requirements for rabbits vary between 0.01 and 0.15 mg/kg diet DM (Blas and Wiseman 2010)
• 0.24 to 0.41 mg Se/kg diet is optimal for growth and antioxidant status in meat rabbits (Zhang, Zhu et al. 2011)
• supra-nutritional Se accumulates in edible tissues, potentially posing a risk to food safety (Marounek, Dokoupilová et al. 2009)
• excessive Se supplementation also results in decreased biomechanical strength of bones and pronounced lesions (Turan, Balcik et al. 1997, Turan, Zaloglu et al. 1997)
• The CFIA provided Health Canada with data on Se transfer to milk, meat, and eggs. Health Canada assessed this data and has indicated that 1 mg/kg total selenium in the diet should not result in Se concentrations of concern in foods of animal origin

Considerations:

• reported zinc (Zn) requirements for rabbits vary between 30 and 70 mg/kg diet DM (Blas and Wiseman 2010)
• excretion of Zn from livestock is of increasing environmental concern (Moreno-Caselles, Moral et al. 2002, Monteiro, Lofts et al. 2010)
• use of Zn supplements (greatly exceeding requirements) in rabbit feed also threatens food safety through the potential emergence and spread of antibiotic resistance pathogens
• Bentley and Grubb (1991) compared a control diet to a diet supplemented with Zn (to provide 5000 µg/g or 5000 mg/kg); It was determined that both groups of rabbits grew at the same rate but rabbits supplemented with Zn had accumulated significant Zn in their tissues
• current authorised maximum of Zn in feed in the European Union is 150 mg Mn/kg diet (European Union Commission 2006)

Vitamins

Considerations:

• recommended level for Vitamin A in rabbit feed is: 6,000 IU Vitamin A/kg diet for fattening rabbits and 12,000 IU Vitamin A/kg diet for lactating and gestating does (Lebas 1988, Cheeke 1994)
• Cheeke (1987) reported that levels above about 40 000 IU/kg diet may adversely affect reproduction including poor conception rates and high frequency of resorptions and delivery of stillborn kits. Surviving kits have slow growth rates and congenital abnormalities including cleft palate and hydrocephalus
• vitamin A accumulates in the liver with toxic levels associated with liver concentrations of 300 mg/kg
• presumed upper safe limit for Vitamin A in rabbit feed is 16,000 IU/kg feed (NRC 1987)

Considerations:

• vitamin D should be supplied at a level of 800 to 1,000 IU/kg and should never exceed 2,000 IU/kg diet (Lebas 2000)
• maximum authorised content of Vitamin D in rabbit feed in the European Union is 2,000 IU/kg feed (European Union Commission 2004)
• vitamin D supplied in excess of metabolic needs is associated with calcification of soft tissues (mainly kidneys) in rabbits fed diets as low as 3,250 IU/kg for 4 to 10 weeks (Loliger and Vogt 1980, Kamphues, Carstensen et al. 1986)

Considerations:

• 50 IU Vitamin E/kg diet is recommended for rabbits (Lebas 1988, Cheeke 1994)
• NRC (1987), noted most species should tolerate at least 20 times nutritionally adequate levels of vitamin E, and that a presumed upper safe level is 75 IU/kg-BW; with feed intake ranging up to 4% BW for rabbits, a presumed upper safe level of 1,875 IU/kg DM is proposed
• while EFSA (2010) indicates that more than 200 IU vitamin E/kg complete feeds is not desirable in feeding practice, Lebas (2000) reviewed studies feeding greater than 200 IU vitamin E/kg of feed which show improved carcass quality and stability due to its deposition in fat and antioxidant activity reducing lipid oxidation