Proposal - Maximum Nutrient Values for Beef and Dairy Cattle Feeds

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; and
• 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 beef and dairy cattle 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; and
• 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, 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, the feed can be exempted from registration. 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.

In the case of beef and dairy cattle feeds, the original Table 4 established nutrient ranges in complete feed (grain portion) only. However, the National Research Council (2001, 2007, and 2016) report nutrient requirements for dairy cattle, beef cattle, and small ruminants on a total diet dry matter basis. Many factors – breed, size, reproduction stage, lactating stage, climate, type of forages and grains, on-farm feed management and practices, environmental conditions among others – have an impact on the variability of the daily feed intake. As total daily ration for ruminants includes forages, establishing nutrient ranges on the basis of complete feeds only does not take into consideration the nutrient contribution from the forage portion of the total daily diets and may lead to over supplementation of certain nutrients especially when the forages contain high level of nutrients and constitute a greater proportion of the daily diets.

As indicated in the 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:

1. Table 4 be removed from the Regulations and no longer serve as a trigger to register feeds based on specified ranges of nutrient content;
2. maximum nutrient levels be established and incorporated by reference for beef and dairy cattle feeds; and,
3. 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, 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; and,
• nutrient maximum levels will be incorporated by reference in the Feeds Regulations to facilitate updating, as necessary.

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 (e.g., 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 (e.g., 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 beef and dairy cattle nutritional requirements and maximum tolerable dietary nutrient levels was conducted by the CFIA to determine:

• nutrient levels that may impact the health and safety of the respective livestock, humans, and environment;
• nutrient levels that support a nutritional purpose as opposed to a therapeutic purpose; and,
• 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 beef and dairy cattle feeds included:

• data and information gathered from nutrition scientists and expert consultants in academia and industry (based on scientific literature, nutrient requirements, intakes and nutrient concentrations in forages, and standard feeding practices) during the review of Table 4 which took place during the mid-2000s (Drs. Karen Beauchemin and Karen Koenig 2006, 2009)
• recommendations and formal opinions provided by other national authorities and food safety agencies (e.g., the National Research Council of the National Academies, the European Food Safety Authority, etc.);
• research published in peer-reviewed literature (e.g., the Journal of Animal Science, Journal of Dairy Science, Journal of Nutrition, etc.); and,
• guidance document on classification of veterinary drugs and livestock feeds

Appendix I sets out the proposed maximum nutrient values for beef cattle feeds.
Appendix II sets out the proposed maximum nutrient values for dairy cattle 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 all classes of cattle. 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 the various classes of cattle 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. Where practical, classes of dairy or beef cattle with similar maximums have been grouped or a common and rounded nutrient value is presented across all classes.

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.

In some cases, the highest values generated have been used as the maximum level for all classes, if there were no known food safety or environmental safety issues for any particular class. For others, where the MTLs have been exceeded, the MTLs have been used as the maximum safety values for that class of cattle. 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 Appendices.

Anticipated Outcomes

This modernized regulatory approach to the oversight of maximum nutrient content in beef and dairy cattle 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; and,
• reduce the regulatory burden on industry wishing to get innovative products into the marketplace.

While this proposal is specific to beef and dairy cattle feeds, future proposals will be developed for additional species subject to the Feeds Regulations and include proposed maximum nutrient values for the species in question.

Stakeholders will be 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 August, 18^th, 2017 to:

Sergio Tolusso
Canadian Food Inspection Agency
Animal Feed Division
59 Camelot Drive
Ottawa, ON K1A 0Y9
Email: Sergio.tolusso@inspection.gc.ca
Fax: 613-773-7565

Appendix I – Proposed Maximum Nutrient Values for Beef Cattle Feeds

Beef Cattle Classes and Average Intakes: (Dry Matter Basis (DM)) ^{Table Note 1} , ^{Table Note 2} , ^{Table Note 3}

Class of Beef Cattle	Class Codes	Total Dry Matter Intake (kg DM/day)	Complete Feed Intake (kg DM/day)	Forage Intake (kg DM/day)
Lactating cow, 600 kg, mature cow from calving to weaning of calf at 6 mo. of age	LT	13.5	2	11.5
Dry pregnant cow, 600 kg, mature cow from weaning of calf to calving	DC	12	1	11
Growers, medium energy diet, ≥ 80% forage, 350 kg, includes growing and replacement cattle (including bulls)	GM	9	2	7
Growers, high energy diet, 30 to 70% forage, 350 kg, weaning to 1 year of age, includes growing cattle (including bulls)	GH	9	5	4
Finishers, high energy, ≤ 20% forage, 450 kg, includes growing cattle, yearling cattle and bulls	F	11	10	1
Calves, birth to weaning at 6 months of age, < 200 kg	C	5	1.5	3.5
Red veal calves, market weight 200 to 300 kg	RV	6	6	0

Table Notes

Table Note 1

Intakes may vary under different production situations; maximum intakes may exceed average intakes.

Return to table note 1 referrer

Table Note 2

Assumption: Dry matter content of complete feeds at 90%.

Return to table note 2 referrer

Table Note 3

Adapted from Revised Beef Table 4 recommendations (Beauchemin and Koenig, 2006, 2009).

Return to table note 3 referrer

Macro-minerals

Calcium (Ca)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	2	1.5
DC	2	1.0
GM, GH	2	1.5
F	2	1.5
C	2	1.0
RV	2	1.5

Rationale:

• NRC (2005) reports the maximum tolerable level for dietary Ca as 1.5% DM for ruminants
• Higher levels of dietary Ca, can affect metabolism of phosphorus (P), magnesium (Mg) and other trace minerals (NRC 2005)
• In pre-ruminant calves, diet Ca concentration exceeding 1.2% DM can interfere with fat use (NRC 2005)
• Pre-partum dry cow diets high in Ca (1.1 to 1.5% of DM) are not recommended, as these levels have been associated with risk of milk fever (Lean et al. 2006)

Phosphorus (P)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	1	0.7
DC	1	0.7
GM, GH	1	0.7
F	1	0.7
C	1	0.7
RV	1	0.7

Rationale:

• NRC (2005) states the maximum tolerable level of P in cattle as 0.7% DM
• Manure excretion of P can be an environmental issue (runoff from waste or application of cattle waste to soil) and is substantially greater when cattle are fed P in excess of nutritional requirements (NRC, 2016)
• Studies reported in NRC (2016), suggests that the P requirements for finishing cattle is less than the typical P requirements for feedlot cattle (0.3-0.5%DM)
• In cases of proper feed formulations for the typical production conditions the MTL is rarely reached

Magnesium (Mg)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	0.5	0.4
DC	0.5	0.4
GM, GH	0.5	0.4
F	0.5	0.4
C	0.5	0.4
RV	0.5	0.4

Rationale:

• NRC (2016) reports the minimum Mg requirements for beef cattle as 0.1% for growing, finishing cattle, 0.12% for gestating cows and 0.2% for lactating cows
• NRC (2016) states the maximum tolerable level of Mg for beef cattle as 0.4%DM
• Cows fed 0.39% Mg showed no adverse health effects (NRC, 2016)

Sodium (Na)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	2.4	1.2
DC	2.4	1.8
GM, GH	2.4	1.8
F	2.4	1.8
C	2.4	1.8
RV	2.4	1.8

Rationale:

• NRC (2016) recommends the minimum requirements for Na in non-lactating beef cattle as 0.06 -0.08%DM, and 0.1% DM for lactating beef cows
• NRC (2005) reports the maximum tolerable dietary sodium chloride level (salt) as 3.0% (approximately 1.2% Na) for lactating cows and 4.5% (approximately 1.8% Na) for growing cattle
• NRC (2005) suggests that about 1 g salt/kg BW can be consumed by ruminants without affecting feed intake. For example: a 450 kg feedlot steer would be expected to consume 11 kg DM /day, its voluntary intake of salt would be 450g or 4.1% salt (approx. 1.8% Na)
• Cows can tolerate high Na diets as long as non-saline water is readily available, however diets high in Na increase urine excretion and manure output

Potassium (K)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	3	2
DC	3	2
GM, GH	3	2
F	3	2
C	3	2
RV	3	2

Rationale:

• The minimum K requirements recommended by NRC (2016) for beef cattle are: 0.6% DM for grower- finisher cattle and gestating cows and 0.7% for lactating cows
• The maximum tolerable level of K in cattle is 2.0% DM (NRC, 2016)
• Forages are excellent sources of K, usually containing between 1 and 4% (NRC, 2016)
• Increasing the K content of a liquid feed from 1.2% to 5.8% DM basis (above the MTL) resulted in the deaths of calves as a result of cardiac insufficiency (NRC, 2016)

Sulfur (S)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	0.4	0.5
DC	0.4	0.5
GM, GH	0.4	0.5
F	0.4	0.3
C	0.4	0.3
RV	0.4	0.3

Rationale:

• NRC (2016) recommends the minimum S requirement for all classes of beef cattle as 0.15% DM
• Dietary S requirements may be greater when urea and other non-protein nitrogen sources are used or with matured forages, or forages grown in S deficient soils
• The MTL of S for cattle is 0.3% DM for cattle on high concentrate diets (85%) and 0.5% for cattle on high forage diets (at least 40% forage) (NRC 2005)
• Cattle fed diets less than 15% forages are at risk of S toxicity (polioencephalomalacia) and therefore the MTL of 0.3%DM was used as the maximum safety limit for those consuming low forage; and MTL of 0.5%DM for beef cattle consuming high forage diets (> 40%)

Trace Minerals

Cobalt (Co)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	10	1
DC	10	1
GM, GH	10	1
F	10	1
C	10	1
RV	10	1

Rationale:

• NRC (2016) recommends the minimum requirements for Co for all classes of beef cattle as 0.15mg/kg DM compared to the previous level of 0.10 mg/kg dietary DM (1996)
• NRC (2016) recommends the amount of Co required for stressed calves as 0.1-0.2 mg/kg DM (NRC 2016)
• NRC (2005) reports the MTL for cattle as 25 mg/kg DM
• Cattle do not have a dietary requirement for vitamin B12. Ruminal microorganisms are capable of synthesizing B12 from dietary Co
• The EU authorizes the maximum Co content for all ruminant diets at 1 mg/kg DM (EFSA, 2009, EFSA 2013)

Copper (Cu)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	50	30
DC	50	30
GM, GH	50	30
F	50	30
C	50	30
RV	50	30

Rationale:

• NRC (2016) reports the minimum Cu requirement for all classes of beef cattle as 10 mg/kg DM
• Stressed calves require about 10-15 mg/kg DM (NRC 2016)
• The MTL for all cattle is 40 mg/kg DM (NRC 2005)
• The MTL value assumes normal molybdenum (Mo) concentrations (1-2 mg/kg) and S concentrations (0.15-0.25%). If Mo and S concentrations are below these levels, Cu may become toxic at lower levels
• Cu toxicity can occur in cattle as a result of excessive supplementation of Cu. Long term feeding of diets with levels slightly less than the MTL (37 mg/kg total Cu) resulted in clinical Cu toxicity (Bradley 1993)

Iodine (I)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	10	1.3
DC	10	1.3
GM, GH	10	1.3
F	10	1.3
C	10	0.7
RV	10	0.7

Rationale:

• The minimum requirement for I for all classes of beef cattle is 0.5 mg/kg DM as reported by NRC (2016)
• Stressed calves require about 0.3-0.6 mg/kg DM (NRC 2016)
• Iodine is usually supplemented in diets or in free-choice minerals as calcium iodate or ethylenediamine dihydroiodide (EDDI)
• The MTL for all cattle is reported at 50 mg/kg DM (NRC 2005)
• The US Food and Drug Administration Regulations has a maximum limit of I supplementation from EDDI of 10 mg/day (NRC 2001); therefore for a dry beef cow consuming about 12 kg/d of diet DM (for example) the maximum I would be about 0.83 mg/kg diet DM

Iron (Fe)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	750	500
DC	750	500
GM, GH	750	500
F	750	500
C	750	500
RV	750	500

Rationale:

• The minimum requirement for Fe for all classes of beef cattle is 50 mg/kg DM (NRC 2016)
• Studies with young calves fed milk diets have shown that 40-50 mg Fe/kg is adequate to support growth and reduce anemia (Bernier et al. 1984)
• Stressed calves require 100-200 mg/kg DM
• The MTL for all cattle is reported at 500 mg/kg DM (NRC 2005)
• Fe toxicity caused diarrhea, metabolic acidosis, hypothermia and decreased gain and intake (NRC 2005)
• Animals exposed to excessive amounts of Fe preferentially deposit it in the liver, spleen, and bone marrow, rather than the muscle (NRC 2005)
• Forages are abundant in Fe; as such the maximum safety limit is set to the MTL to accommodate the high intrinsic level that may be present in forages

Manganese (Mn)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	200	200
DC	200	200
GM, GH	200	150
F	200	150
C	200	150
RV	200	150

Rationale:

• The minimum requirement for Mn for growing-finishing cattle is reported at 20 mg/kg DM and 40 mg/kg DM for gestating and lactating cows (NRC, 2016)
• Stressed calves require a minimum of 40-70 mg/kg DM (NRC 2016)
• The MTL of Mn for beef cattle is 1000 mg/kg DM (NRC 2016)
• The concentration of Mn in forages varies greatly depending on plant species, soil pH and soil drainage

Selenium (Se)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	0.3	0.5
DC	0.3	0.5
GM, GH	0.3	0.5
F	0.3	0.5
C	0.3	0.5
RV	0.3	0.5

Rationale:

• The requirement for Se for all classes of beef cattle is reported at 0.1 mg/kg DM, with stressed calves requiring about 0.1-0.2mg/kg DM (NRC 2016)
• The MTL for ruminants is reported as 5 mg/kg DM (NRC 2005), however the proposed maximum levels have been reduced due to levels that may end up in edible tissues
• Se toxicity occurs due to over supplementation of Se sources or excessive consumption of plants naturally high in Se (NRC 2016)
• The EU recommends a maximum of total 0.5 mg Se/kg in complete feed. For example: a growing steer with an intake of 9 kg/d DM would consume 4.5 mg Se/day

Zinc (Zn)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	250	150
DC	250	150
GM, GH	250	150
F	250	150
C	250	200
RV	250	200

Rationale:

• The requirement for Zn for all classes of beef cattle is 30 mg/kg DM (NRC 2016) with stressed calves requiring about 75-100 mg/kg DM (NRC 2016)
• The MTL for all cattle is 500 mg/kg DM (NRC 2005)
• EFSA (2014) recommended a reduction of dietary Zn in animal nutrition to decrease the Zn load in the environment; therefore max levels are set lower than the MTL levels
• Calves may require more as per their requirements during stress periods

Vitamins

Vitamin A

Class	Current (IU/day)	Proposed (IU/kg of diet DM)
LT	100,000	10,000
DC	100,000	10,000
GM, GH	100,000	10,000
F	100,000	10,000
C	100,000	10,000
RV	100,000	10,000

Rationale:

• The requirement for feedlot cattle is 2,200 IU/kg DM, 2800 IU/kg DM for pregnant cows and 3,900 IU/kg DM for lactating beef cows (NRC 2016)
• The MTL for all cattle is 66,000 IU/kg DM (NRC 1987)
• For example: for a feedlot steer with a DM intake of 11 kg/d the maximum vitamin A consumed would be 110,000 IU/day

Vitamin D

Class	Current (IU/day)	Proposed (IU/kg of diet DM)
LT	33,000	2,200
DC	33,000	2,200
GM, GH	33,000	2,200
F	33,000	2,200
C	33,000	2,200
RV	33,000	2,200

Rationale:

• The vitamin D requirement of beef cattle is 275 IU/kg DMI or approximately 5.7IU/kg BW (NRC, 2016)
• The MTL for all cattle is 2,200 IU/kg DM (NRC 1987)
• For example: for a lactating cow with a dietary intake of 13.2 kg/d DM the maximum vitamin D level consumed would be 29,040 IU/day

Vitamin E

Class	Current (IU/day)	Proposed (IU/kg of diet DM)
LT	NRS	100
DC	NRS	100
GM, GH	NRS	100
F	NRS	100
C	NRS	150
RV	NRS	150

Rationale:

• The vitamin E requirement for beef cattle is 35 IU/kg DM
• The requirement for stressed calves is set for 400-500 IU/d or about100 IU/kg DM
• The MTL for all cattle is 2,000 IU/kg DM (NRC 1987)
• For example: for calves with a DM intake of 5kg the maximum amount consumed would be 750 IU/day

Appendix II – Proposed Maximum Nutrient Values for Dairy Cattle Feeds

Dairy Cattle Classes and Average Intakes: (Dry Matter Basis) ^{Table Note 4}, ^{Table Note 5}, ^{Table Note 6}

Class of Dairy Cattle	Class Codes	Total Dry Matter Intake (kg DM/day)	Complete Feed Intake (kg DM/day)	Forage Intake (kg DM/day)
Lactating Cow	LT	23	11.5	11.5
Dry Cow	DC	12	2	10
Heifer (3 months to calving)	H	7	2	5
Calf (birth to 3 months)	C	2.5	2	0.5

Table Notes

Table Note 4

Intakes may vary under different production situations; maximum intakes may exceed average intakes

Return to table note 4 referrer

Table Note 5

Assumption: Dry matter content of complete feeds at 90%.

Return to table note 5 referrer

Table Note 6

Adapted from Revised Dairy Cattle Table 4 recommendations (Beauchemin and Koenig, 2006, 2009)

Return to table note 6 referrer

Macro-minerals

Calcium (Ca)

Class	Current (% of complete feed, as fed)	Proposed (as % of diet DM)
LT	2.5	1.5
DC	2.5	1.0
H	2.5	1.5
C	2.5	1.5

Rationale:

• The NRC (2001) recommended dietary Ca requirement is 0.65, 0.45, 0.65 and 0.70 % of DM for lactating cows, dry cows, heifers, and calves respectively
• The maximum tolerable dietary Ca level is 1.5% of DM for ruminants (NRC 2005)
• Pre-partum dry cow diets high in Ca (1.1 to 1.5% of DM) are not recommended, as this dietary concentration range has been associated with peak milk fever risk (Lean et al. 2006)

Phosphorus (P)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	1.3	0.7
DC	1.3	0.7
H	1.3	0.7
C	1.3	0.7

Rationale:

• The NRC (2001) recommended dietary P requirement is 0.35, 0.25, 0.30 and 0.45 % for lactating cows, dry cows, heifers, and calves respectively
• MTL of P in cattle is 0.7% DM basis (NRC 2005)
• Manure excretion of P can be an environmental issue and is substantially greater when lactating cows are fed P at amounts in excess of requirement (Wu et al. 2000, Wu, Z 2005)

Magnesium (Mg)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	1.0	0.6
DC	1.0	0.6
H	1.0	0.6
C	1.0	0.6

Rationale:

• The NRC (2001) recommended dietary Mg requirement is 0.20, 0.15 for lactating and dry cows respectively and 0.1% for heifers and calves
• The maximum tolerable dietary Mg level is 0.6% (NRC 2005)

Sodium (Na)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	2.4	1.2
DC	2.4	1.8
H	2.4	1.8
C	2.4	1.8

Rationale:

• The NRC (2001) recommended dietary Na requirement is 0.22, 0.12, 0.10 and 0.15 % for lactating cows, dry cows, heifers, and calves respectively
• The maximum tolerable dietary sodium chloride level is 3.0% (= approximately 1.2% Na) for lactating cows and 4.5% (= approximately 1.8% Na) for growing cattle (NRC 2005)

Potassium (K)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	3	3.0
DC	3	2.0
H	3	3.0
C	3	3.0

Rationale:

• The NRC (2001) recommended dietary K requirement is 0.90, 0.55, 0.50 and 0.65 % for lactating cows, dry cows, heifers, and calves respectively
• The maximum tolerable dietary K level is 3.0% of DM for all classes of dairy cattle (NRC 2005)
• Diet K above 2.0 % for dry cows increased the incidence of milk fever (Goff and Horst 1997)

Sulfur (S)

Class	Current (% of complete feed, as fed)	Proposed (% of diet DM)
LT	0.5	0.5
DC	0.5	0.5
H	0.5	0.5
C	0.5	0.5

Rationale:

• The NRC (2001) recommended dietary S requirement is 0.2 % of DM for all classes of dairy cattle
• MTL of S in cattle is 0.5% of DM if consuming at least 40% forage
• MTL for diets with more than 85% concentrate is 0.30% (NRC 2005)

Trace Minerals

Cobalt (Co)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	10	1.0
DC	10	1.0
H	10	1.0
C	10	1.0

Rationale:

• The NRC (2001) recommended dietary Co requirement is 0.11 mg/kg DM for all classes of dairy cattle
• The MTL for cattle is 25 mg/kg DM (NRC 2005)
• The EU authorized total maximum Co content for all ruminant diets is 1 mg/kg (EFSA, 2009, EFSA 2013)

Copper (Cu)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	100	40
DC	100	40
H	100	30
C	100	30

Rationale:

• The NRC (2001) recommended dietary Cu requirement is 14 mg/kg DM for lactating and dry cows and 12 and 10 mg/kg DM for heifers and calves respectively
• The MTL for all cattle is 40 mg/kg DM (NRC 2005)
• The MTL value assumes normal Mo concentrations (1-2 mg/kg) and S concentrations (0.15-0.25%). If Mo and S concentrations are below these levels, Cu may become toxic at lower levels

Iodine (I)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	10	1.3
DC	10	1.0
H	10	0.7
C	10	0.7

Rationale:

• The NRC (2001) recommended dietary I requirement is 0.50, 0.40, 0.28 and 0.25 mg/kg DM for lactating cows, dry cows, heifers, and calves respectively
• The MTL for all cattle is 50 mg/kg DM (NRC 2005)
• Feeding I in excess of requirements may result in undesirably high level of iodine in milk
• The US Food and Drug Administration Regulations specify a maximum limit of I supplementation from EDDI of 10 mg/day (NRC 2001); therefore for a cow consuming 23 kg/d of diet, this is equivalent to 0.43 mg/kg of DM

Iron (Fe)

Class	Current (mg/kg of complete feed as fed)	Proposed (mg/kg of diet DM)
LT	50	500
DC	50	500
H	50	500
C	50	500

Rationale:

• The NRC (2001) recommended dietary Fe requirement is 20, 15, 30 and 50 mg/kg DM for lactating cows, dry cows, heifers, and calves respectively
• The MTL for cattle is 500 mg/kg DM (NRC 2005)
• Due to the abundance and high variability of Fe in forages, the maximum limit was set at MTL to accommodate daily diets with forages with an Fe content at the upper limit of the range

Manganese (Mn)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	300	150
DC	300	250
H	300	100
C	300	200

Rationale:

• The NRC (2001) recommended dietary Mn requirement is 20 mg/kg DM for lactating cows, dry cows and heifers and 40 mg/kg for calves
• Recent data suggest that the NRC 2001 Mn requirement may be too low for dry and lactating dairy cows (Weiss and Socha 2005)
• Based on reproduction measures and Mn balance data, diets for lactating and dry cows should contain about 30 and 50 mg/kg of Mn, respectively (Weiss 2005- Update on Trace Mineral Requirements for Dairy Cattle- Proc. Four-State Dairy Nutr. Management Conf. pp 13-21)
• The MTL for cattle is1,000 mg/kg DM (NRC 2001)

Selenium (Se)

Class	Current (mg/kg of complete feed as fed)	Proposed (mg/kg of diet DM)
LT	0.3	0.5
DC	0.3	0.5
H	0.3	0.5
C	0.3	0.5

Rationale:

• The MTL for cattle is 5 mg/kg DM (NRC 2005)
• The NRC (2001) recommended dietary Se requirement is 0.30 mg/kg DM for all classes of dairy cattle. The majority of the data supporting this requirement were generated from studies in which 0.3 mg/kg of supplementary Se was fed. The total dietary Se in these studies ranged from 0.35 to 0.40 mg/kg (NRC, 2001)
• In the EU the total maximum authorized content of Se in complete feeds is 0.5 mg/kg (EFSA, 2016)

Zinc (Zn)

Class	Current (mg/kg of complete feed, as fed)	Proposed (mg/kg of diet DM)
LT	500	280
DC	500	130
H	500	130
C	500	200

Rationale:

• The NRC (2001) recommended dietary Zn requirement is 55, 25, 25 and 40 mg/kg for lactating cows, dry cows, heifers, and calves respectively
• The MTL for all cattle is 500 mg/kg DM (NRC 2005)

Vitamins

Vitamin A

Class	Current (IU/day)	Proposed (IU/kg of diet DM)
LT	200,000	10,000
DC	200,000	20,000
H	200,000	10,000
C	200,000	10,000

Rationale:

• The NRC (2001) recommended dietary vitamin A requirement is 3260, 7000, 3200 and 4000 IU/kg DM for lactating cows, dry cows, heifers, and calves respectively
• The MTL for all cattle is 66,000 IU/kg DM (NRC 1987)
• For example: a lactating cow with a DM intake of 23 kg/d the maximum vitamin A consumed would be 230,000 IU/day

Vitamin D

Class	Current (IU/day)	Proposed (IU/kg of diet DM)
LT	33,000	2,200
DC	33,000	2,200
H	33,000	2,200
C	33,000	1,500

Rationale:

• The NRC (2001) recommended dietary vitamin D requirement is 916, 1800, 1200 and 600 IU/kg for lactating cows, dry cows, heifers, and calves respectively
• The MTL for all cattle is 2,200 IU/kg DM (NRC 1987)
• For example: a lactating cow with a DM intake of 23 kg/d the maximum vitamin D consumed would be 50,600 IU/day

Vitamin E

Class	Current (IU/day)	Proposed (IU/kg of diet DM)
LT	NRS	80
DC	NRS	200
H	NRS	80
C	NRS	80

Rationale:

• The NRC (2001) recommended dietary vitamin E requirement is 24, 80, 32 and 25 IU/kg for lactating cows, dry cows, heifers, and calves respectively
• The MTL for all cattle is 2,000 IU/kg DM (NRC 1987)
• Daily supplementation of 3,000 IU (250 IU/kg of DM) of vitamin E to dairy cows during the dry period had adverse effects on udder health postpartum (Bouwstra et al. 2010)
• For example: a lactating cow with a DM intake of 23 kg/d the maximum vitamin E consumed would be 1,840 IU/day