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Table 1 gives the maximum total DMI (from roughage and grain mixture) that milking cows can eat in mid-to-late lactation. The table lists DMI as a % of body weight and in kg per day. A cow weighing 550 kg giving 30 kg milk can eat 3.7% of her body weight in DM daily or about 20.4 kg. A bigger cow (650 kg) at the same milk yield can eat only 3.4% of her weight in DM (22.1 kg per day). Bigger cows at higher milk yield, can eat more feed DM.

Table 1. Dry matter intake by cows in mid to late lactation
(% of body weight and kg per day)

Total ration DM should be between 50 and 75%. Wetter or drier rations limit DM consumption. When silages are fed heavily, expect DMI to decline by 0.02% of body weight for each 1% decrease in total ration DM. Example: 40% DM ration - 50% DM limit = -10 x 0.02% x 600 kg cow = -1.2 kg DMI per day.

Maximum DMI depends on continuous access to fresh, clean, cool water. You should provide water in a well lit area within 15 metres of the feed bunk. Cows drink about 5 litres of water for each kg milk (eg. a cow producing 40 litres of milk will consume 200 litres of water). Cows are thirsty and hungry immediately after milking. Decreasing water intake by 40% results in a 16 to 24% decline in DMI and a large decrease in milk yield. Cows need more water in hot weather.

Cows will reduce DMI when environmental temperature exceeds 24·C, usually due to reduced forage intake. Cows experience severe heat stress when temperature exceeds 27·C, when relative humidity exceeds 80% or when the two values added exceed 100. DMI may be depressed by 15 to 20% on hot summer days. Summer DMI improves when you offer at least 60% of the ration is fed at night, and if feed and water are in shaded areas.

Milking cows can consume 1.8 to 2.2% of body weight daily as DM from average quality dry roughage. Roughage quality is partly determined by fibre levels. Fibre content increases as the forage crop matures. High fibre forage has lower palatability, reduced protein levels, and is less digestible than high quality material. Undigested feed cannot pass out of the rumen. The cow cannot consume more feed until the feed in the rumen is digested. High fibre forages reduce DMI. A cow can eat 3% of body weight as DM from excellent hay but only 1.5% from poor hay (Table 2).


Table 2. Maximum DMI (kg) of legume hay or haylage of different quality

 

Hay Crop Quality	Nutrient Content (% of DM)			Haycrop DMI (kg)
				DMI as a % of Body Weight	Cow Body Weight (kg)
	CP	ADF	NDF		400	500	600
Excellent	>18	<33	<43	3.0%	12.0	15.0	18.0
Good	16-18	33-37	43-48	2.5%	10.0	12.5	15.0
Fair	13-15	38-41	49-53	2.0%	8.0	10.0	12.0
Poor	<13	>40	>53	1.5%	6.0	7.5	9.0
CP is crude protein, ADF is acid detergent fibre, NDF is neutral detergent fibre. Technical words used in dairy nutrition are described in OMAF Factsheet, Livestock Feed Terms Defined, Agdex 400/60.

Nutrient value of roughages depends on plant species, stage of maturity, and on harvesting and storage systems and losses. The hay crop should be harvested early (less than 10% in flower), and stored correctly to provide high quality roughage for the milking herd. Refer to OMAF Publication 30, Forage Production and Factsheet Protein Supplements from Forage Legumes, Agdex 120/81 for information on forage quality.

Table 2 values are maximum levels, based on forage only. When a cow eats more grain, roughage consumption usually decreases. Five to seven kg of grain probably will not decrease a cow's roughage intake. However, above that level of grain, intake of roughage declines by about 1 kg for each 2.5 kg extra grain fed. In most feeding trials using forage and grain, DMI from roughage is usually under 2% of body weight.

Some research suggests that forage DMI is related to NDF content. For example, forage NDF intake in mid lactation is about 0.9% of body weight. This means that a 650 kg cow could consume:

650 x 0.9% = 5.85 kg NDF.
If this was excellent legume hay (42% NDF) she could eat:
5.85 x 100/42 = 13.9 kg of DM from this hay.
If this was poor legume hay (54% NDF) she could only eat:
5.85 x 100/54 = 10.8 kg of DM from this hay.

Ration NDF should be 25 to 28% of DM. Most NDF (about 75%) should come from roughages. Silages should be chopped at 95 mm (3/8 in.) theoretical length of cut. This ensures that at least 15 to 20% of the particles are more than 3.8 cm (1 1/2 in.) long, to stimulate cud chewing. Cows should spend most of their non-eating time chewing their cud. Underfeeding "effective" fibre causes off-feed problems and fat test depression. When the ration contains adequate "effective" fibre and NDF from forages, it is not necessary to include long stemmed dry hay in the daily ration.

A minimum level of forage intake should be set. Very low forage intake leads to rumen acidosis, milk fat depression and twisted stomachs. A ration ADF of 19% and NDF of 28% (of DM) keeps the rumen functioning properly and promotes normal cud chewing.

For high producing, early lactation cows, at least 40% of the ration DM should come from roughages. This gives a minimum forage to concentrate ration of 40:60. When corn silage is above 45% of the roughage DM, a 45:55 ratio is appropriate. More roughage (less grain) can be fed to cows in late lactation or at low production levels. Forage: concentrate ratio's above 80:20 can support 20 kg of milk yield if roughage quality is good.

Daily grain allowance after dry off will depend on roughage quality. When roughage quality is poor, 2 to 4 kg (4 to 9 pounds) of grain may be required daily to maintain cow body condition. If roughages are good, but cows are thin, 2 to 4 kg may be required to allow for moderate and gradual weight gain during the dry period.

Individualized feeding programs can be designed if dry cows are grouped by body condition and closeness to calving. A balanced dry cow ration should contain adequate fibre, protein, vitamins and minerals (Table 6). A proper dry cow ration prevents metabolic diseases and retained placentas and keeps cows on feed at calving. See OMAF Factsheet Health Management Practices for Dry Cows, Agdex 414/20.


Table 6. Guidelines for Composition of Complete Rations

	Levels of Milk Produced Per Day				Early Lactation 0-3 Weeks	Dry
	<20 kg <45 lb	30 kg 65 lb	40 kg 90 lb	50 kg 110 lb
Protein
Crude protein %	12- 15	16	17	18	19	12
DIP, % of CP	63	61	60	55	55	-
UIP, % of CP	37	39	40	45	45	-
Energy
NEI, Mcal/kg	1.42-1.52	1.62	1.72	1.72	1.67	1.25
TDN, % of DM	63 - 67	71	75	75	73	56
Fibre
Crude fibre, %	17	17	15	15	17	22
ADF, %	21	21	19	19	21	27
NDF, %	28	28	25	25	28	35
Minerals
Calcium, %	.43-.51	.58	.64	.66	.77	.39
Phosphorous, %	.28-.33	.37	.41	.41	.48	.24
Potassium, %	.9	.9	1.0	1.0	1.0	.65
Magnesium, %	.2	.2	.25	.25	.25	.2
Sulphur, %	.2	.2	.2	.2	.2	.16
Sodium, %	.18	.18	.18	.18	.18	.1
Chlorine, %	.25	.25	.25	.25	.25	.2
Manganese,ppm	40	40	40	40	40	40
Copper, ppm	10	10	10	10	10	10
Zinc, ppm	40	40	40	40	40	40
Iron, ppm	50	50	50	50	50	50
Cobalt, ppm	.1	.1	.1	.1	.1	.1
Iodine, ppm	.6	.6	.6	.6	.6	.6
Vitamins
Vitamin A, lU/kg	3200	3200	3200	3200	4000	4000
Vitamin D, lU/kg	1000	1000	1000	1000	1000	1200
VitaminE, lU/kg	15	15	15	15	15	15

Lead Feeding (2 to 3 weeks pre-calving)
To allow rumen bacteria to adjust to changes in the ration, the cow should be started on some grain, and the level increased slowly before calving time. In group fed herds, this can be done with a "close up ration" group.

Two weeks before the expected calving date, increase the cow or heifer grain allowance to a maximum of 1% of her body weight as grain. This is lead feeding. By calving day, 5 to 7 kg (11 to 15 pounds) for Holstein cows (Figure 1) and 4 to 5 kg (9 to 11 pounds) per day for Jersey cows is appropriate.

Figure 1. Protein and Grain Addition to Close-up and Early Lactation Cows.



Lead feeding improves appetite at calving and in early lactation. The milking cow grain mix may cause milk fever if it is too high in calcium. Barley, oats or corn grain, and a proper dry cow mineral, is ideal for lead feeding. Small amounts (0.5 to 1 kg) of protein supplement can be topdressed just prior to calving.

Some forage fed to the milking cows can be fed pre-calving. Large amounts of high quality legume hay or haylage may cause milk fever. Avoid high corn silage diets to prevent twisted stomachs. If more than 7 kg (15 pounds) of corn silage is fed, reduce the grain levels for lead feeding. Long stemmed hay should be a large part of the precalving diet.

In total mixed ration (TMR) fed herds, offer 8 to 9 kg (15 to 20 pounds) of the milking cow TMR to lead feed precalving, plus dry hay. Separate grain feeding is not needed if the milking cow TMR contains high grain levels. Gradual adjustment to the milking cow ration is essential for keeping cows eating and healthy.

About 3 to 4 days after calving, challenge feed your cows and encourage high peak yields by increasing the grain offered. Offer a high protein feed in addition to the major grain (energy) feed in early lactation. Start the protein supplement during the first few days of lactation, if not fed precalving. Protein stimulates appetite and feed digestibility in the just fresh cow. Protein requirements in early lactation are high, at 19% of the diet DM (Table 6). At peak milk production the protein requirement is 18%. Try to get cows up to the maximum amount of the high protein feed by 2 weeks into lactation (Figure 1).

Increase the grain fed gradually. Cows pushed too fast will go off-feed. Most cows can tolerate an increase of 1 kg every other day during the first week, 0.5 kg every other day in week 2 and 0.3 kg every other day in week 3. If lead feeding levels were adequate, this schedule will get cows to their maximum grain and protein intake by 3 to 3 1/2 weeks into lactation.

A sample schedule for protein and grain feeding to close-up and early lactation cows is shown (Figure 1). In this example, peak intake of protein supplement (4.5 kg or 10 pounds) is reached by 10 days in milk. Peak grain intake (10.5 kg or 23 pounds) is reached by 22 days in lactation.

In TMR fed herds where 2 milking cow rations (high and low production level) are fed, cows can be moved into either group. Feeding some TMR prior to calving, will help cows to adapt to high levels of grain in the TMR You may have good success with moving fresh cows into the low group for up to 2 weeks and then changing them to the high group. To reduce stress from competition move several cows at once, and in the evening when activity levels are the lowest. Keep cows eating by feeding TMR free-choice. Cows should have all the feed they want, when they want to eat it. Keep the feed bunks full, and allow for 5% refused feed each day to accomplish this. If the bunk is empty, many cows are hungry and producing less than their potential.


Grain Feeding Levels
Feed according to nutrient requirements once the cow has reached her peak of production (6 to 8 weeks for cows, 10 to 12 weeks for first calf heifers).

Grain requirements depend on:

• milk yield
  
• fat test
  
• stage of lactation
  
• body weight
  
• body condition
  
• quantity of forage eaten
  
• quality of forage

The better the quality of roughage she eats, the less grain she requires. Forage testing and actual measurements of forage intake are needed to formulate a balanced ration for the milking herd. A computer balanced ration should provide a printed grain feeding report with guidelines for cows in early lactation (before peak milk) and in later lactation to allow for

Table 3 gives guidelines for grain feeding levels at various production levels. These grain levels are for mid-to-late lactation cows, fed average quality forages and maintaining body condition. Grain levels in Table 3 are the total of grains (corn, barley) or grain mix, and protein supplement.

Table 3. Post peak grain feeding guidelines based on milk produced

Adjust grain feeding levels in the following situations:

• Table 3 uses average forage quality. When corn silage or excellent hay-crop forage provides most of the roughage, reduce grain fed by 10%. If low quality forage is fed, 10% more grain is required.
  
• Do not feed more grain than the individual cow can safely handle. Feed a maximum of 2 to 2.5% of body weight per head daily as dry grain. For a 650 kg cow, grain maximum is 13 to 16 kg.
  
• Grain in Table 3 is dry grain. Increase these amounts by 5 to 10% if high moisture grains are fed.
  
• Allow for reduced intake by fresh and early lactation cows by increasing grain nutrient density. Feed a high protein feed plus the base grain or grain mix to cows less than 100 days in milk. Provide 1 to 1.5 kg (2 to 3 lb) of supplemental protein for each 5 kg (10 lb) of milk above 35 kg (75 pounds).
  
• Examples
  Cow at 40 kg milk, needs 40/2.5 kg grain = 16 kg
  Production is 5 kg above 35, so 1 to 1.5 kg supplement is needed
  Offer: 15 kg grain plus 1 kg supplement or 14.5 kg grain plus 1.5 kg supplement
  
  Cow at 45 kg milk, needs 45/2.5 kg grain = 18 kg grain
  Production is 10 kg above 35 so 2 to 3 kg supplement is needed
  Offer: 16 kg grain plus 2 kg supplement or 15 kg grain plus 3 kg supplement.
  
  
• Meet the growth needs of first calf heifers by feeding an extra 1 to 1.5 kg (2 to 3 lb) and 0.5 to 1 kg (1 to 2 lb) extra for second calf heifers, above requirements for milk production.
  
• Adjust for the energy required to produce butterfat by feeding 10% more or less grain for each 0.5% increase or decrease in fat % from 4.0%.
  
• Adjust grain intake for flesh needs after peak yield. Add or subtract 2 to 3 kg (4 to 6 pounds) for obviously thin or fat cows, respectively.
  
• Adjust for excessive drops in monthly production. Set grain levels using a maximum drop of 10% of last daily milk yield. This prevents a major decrease in grain allocation for cows in heat or ill on test day. You should check cows with excessive drops in milk yield for subclinical mastitis or other problems and when a group or herd production level drops more than 5 to 10% monthly.
  
• Feed a group of cows, by using a production level that is at least 10 kg (22 lb) above the group average. This prevents large drops in milk when cows enter a lower group, and allows for condition gain in late lactation.

Underfeeding and Overfeeding
Dairy producers often overfeed low producing cows and underfeed high producing, early lactation cows. To correct this error, redistribution of grain will ensure that the high producing cow can support her high level of production.

Underfeeding grain causes:

• low milk production especially in early lactation
  
• excessive body weight loss
  
• lower conception rate
  
• more herd health problems
  
• less income (net returns) over feed costs

Overfeeding is most likely to occur in the later stages of lactation or the dry period. Overfeeding is costly in terms of value of milk being produced, and may lead to overly fat cows. Fat cows have more calving difficulties, reduced appetite after calving, and increased incidence of ketosis, twisted stomach and udder edema. These cows are also more susceptible to bacterial infections such as metritis and mastitis.

With computerized feeders and TMR mixers, an accurate set of scales is necessary. Frequent maintenance, dusting and calibration is essential. Re-calibrate when grain type, purchased feeds, mix composition or forage DM is changing. Monitor DM of forages weekly for TMR's, and modify the composition of the mix as required.

TMR mixing accuracy can be checked by adding 1 kg of brightly coloured candies to a batch and mixing. Collect a small bucket of TMR from the first, middle and last offloaded TMR. Equal numbers of candies should be counted in each bucket. Feed analysis of each portion can also check mixing accuracy. When mixing accuracy is suspect, distribute TMR to the barn in a different order on alternate days. Avoid overloading, as most TMR mixers work at peak efficiency at 60 to 70% capacity.


Changing the Grain Allowance
Ideally, grain allowances for fresh cows should be changed daily. Some computer feeders do this automatically. Hand feeding in a 60 cow tie stall barn is another story. Challenge feed cows for the first 6 to 8 weeks of lactation. Keep cows on feed. If cows refuse grain, reduce the amount and gradually return it to the desired level.

Cows will restore body condition lost in early lactation if peak grain levels are maintained until 10 to 12 weeks in lactation. This encourages reproductive cycling and conception, since this is normally the time when the cow is rebred. A good cow, at high grain intake, will peak in milk at 6 to 8 weeks, and still be producing at this level 3 to 4 weeks later. She will be gaining weight by week 8 to 10 of lactation.

From 10 to 12 weeks until dry off, adjust the grain allowance monthly, based on the DHI test results, and body condition. If only enough grain is offered to cover the milk yield requirements, the cow is unable to gain back needed condition. At dry off, she will be thin, and she will likely produce less milk, fat and protein in the next lactation.

About 2 to 3 kg extra grain is required per day (above what is needed for milk) during the last 100 days of lactation to restore body weight. Energy density of the TMR should also be high enough so that cows dry off at a desired condition score of 3.5 to 4.


Crude Protein Content in the Grain Mixture
Protein content of a grain mixture depends on the type and quality of forage, milk yield, fat % and stage of lactation. Grain mix protein level guidelines (Table 4) are for cows at 25 kg milk, 4% fat per day.

Table 4. Recommended crude protein content and protein fractions in grain mixtures matched with forage programs

Use the low end of the range shown when corn silage has been ammoniated. Level of grain feeding will affect the percentage of crude protein needed in the grain mix. Low producing cows receiving small amounts of grain require more crude protein in the grain mix. The levels and fractions of protein in Table 4 reflect the new N.R.C. Nutrient Requirements of Dairy Cattle (1989).

Protein not digested by rumen microbes is undegradable intake protein (UIP). This is often called "bypass" or "escape" protein because it bypasses the rumen without being digested. Some plant source feeds high in UIP are roasted soybeans, corn distillers grains, brewers grains and corn gluten meal. About 35 to 45% of the ration protein should be UIP. The 35% level is suitable for mid to late lactation cows. Fresh, high producing cows need 40 to 45% UIP in the ration DM. Cows fed high levels of dietary fat require UIP levels of 45 to 50%.

Animal source bypass proteins (meat meal, fish meal, blood meal) are more expensive per tonne than plant bypass proteins. When priced per unit UIP, animal source UIP feeds are economical. Bypass proteins of animal origin contain protein components (amino acids) which are similar to those found in milk. Therefore, animal source proteins are high quality bypass protein. Animal source UIP feeds are not very palatable. Feed them in small amounts or in a commercial or pelleted feed. OMAF Factsheet Protein Supplements for Dairy Rations, Agdex 410/64, contains more information.


Energy, Fibre and Fat Recommendations for Grain Mixtures
Even when eating 14 to 16 kg (30 to 35 pounds) of grain per day, a high producing cow cannot consume enough energy to meet her energy output in early lactation. The cow is forced to rely on body stores of fat to supplement her dietary energy intake. Burning of body fat reserves can supply needed energy, but the dependence on body stores of energy should be kept small.

A lack of dietary energy causes the cow to rely excessively on body reserves. Rapid body fat mobilization, along with low feed and/or energy intake, leads to ketosis (acetonemia). Cows losing weight are in negative energy balance. They show weaker heats and have lower conception rate than cows gaining in condition and in positive energy balance. Most high producing cows, in early lactation are in a mild (subclinical) state of ketosis, which causes few problems except gradual body weight loss.

Corn is the least expensive grain. It is the highest energy grain followed by barley, then oats. Grains contain high levels of starch. When rumen microbes digest starch, they produce acidic end products. Rumen acidity increases, reducing fibre digestion. This may lead to "off feed", a decline in milk yield and fat test depression. Increase the ration energy density by feeding more, high energy grain. Keep fibre levels high enough for good rumen and cow health.

Non-fibre carbohydrates (NFC) are rapidly digested and include sugars, starches and pectin. NFC is calculated as: 100 - (NDF + Crude Protein + Fat + Ash). Non-fibre carbohydrate levels in the total ration dry matter should not fall below 20 to 25%, nor go above 40 to 45%. Rations formulated for 35 to 37% NFC (D.M. basis) should avoid metabolic disturbances related to feeding high levels of starches in grains and concentrate mixtures. For diets high in corn silage or grain, use of high-fibre byproduct feeds may help reduce the starch load on the rumen. Byproducts such as soyhulls, wheat bran, brewers and distillers grains are low in NFC and work well in high production rations.

When grain levels are maximized, a more costly way to increase the energy level is to add fat. Fat is too expensive to feed to any cows that are not in early lactation or above 35 to 40 kg milk. Fat contains over 2.25 times the energy value of grain. Added fat improves energy balance by reducing body weight loss, improving persistence of production and assisting in an early return to positive energy balance.

There are 3 main types of fat:

• unsaturated fats (liquid at room temperature). Eg. corn oil, soy-bean oil (in whole soybeans), cottonseed oil (in whole cottonseed).
  
• saturated fats (solid at room temperature). Eg. tallow.
  
• protected fats: Fats treated or combined with another substance to prevent breakdown in the rumen. Eg. Megalac®, Energy Booster® and other commercial products.
  

Grain mix ingredients naturally contain 3 to 4% fat. Include additional fat to a maximum total of 7 to 8% of ration DM. Multiple sources of fat can be fed. Guidelines are in Table 5. Overfeeding of unprotected fats (especially vegetable oils) is detrimental. About 2.5 kg of roasted beans or whole cottonseed will provided 0.5 kg fat. Exceeding the limits results in rumen metabolism problems, reduced fibre digestion and may depress fat and protein yields test. When including high levels of fat (especially unprotected fat) in the diet make sure that:

• ration calcium levels exceed 1% of diet dry matter
  
• ration magnesium levels exceed 0.3% of diet dry matter
  
• ration Vitamin E levels are increased to 1000 or more I.U. per cow per day to prevent oxidation of the fat and off-flavoured milk
  
• rumen UIP levels are 45 to 50% of ration protein Follow these grain and fat feeding guidelines to allow each cow to reach peak production at or close to her genetic potential. The advantage of maximum peak production is to maintain a higher level of milk yield throughout the lactation.

Table 5. Guidelines for fat inclusion in dairy rations

Type of Fat	Fat (% of DMI)	Fat Intake (kg per day)
Natural sources (forages, grains etc.)	2 - 3%	0.75
Unprotected sources (tallow, oilseeds)	2- 3%	0.5
Protected sources (calcium soaps, prilled fats, encapsulated fats)	2 - 3%	0.5 - 0.6

Processing the Grain Mixture
Grain fed separately (not in a TMR) should be of medium coarse grind or rolled. The rate of starch digestion can be improved if grain is adequately processed. This is desirable when the ration contains high levels of degradable protein. It allows the rumen microbes to use starch and protein simultaneously, and promotes maximum microbial growth. Fine grinding is undesirable when it creates a pasty and unpalatable feed. Finely ground grain may lead to butterfat depression and rumen upsets on high grain diets. In TMR's, where palatability is less of a problem, grain can be processed finely without problems. Whole grain is not readily digestible.

Energy is being wasted when corn appears undigested in the manure. Causes of grain in manure are high grain levels, rapid feed passage, low fibre levels or under processing of grain.

Grind corn and cob meal medium fine. The largest particles should be the size of a pea. Pelleting of the grain mixture is helpful where rapid intake is required, or when grain is only fed in a milking parlour. When fibre levels in the diet are adequate, pelleted feeds will not depress fat percent.


Feeding Management
Use feeding management strategies to improve feed DMI and milk production. Feed management tips are:

• Feed grain meals of less than 4 kg of grain per feeding
  
• Feed grain in several small meals daily rather than two large ones, especially in hot weather
  
• Feed protein supplement after or with the grain meal
  
• Feed a forage meal 1 to 1 1/2 hours before a grain meal
  
• Combine forages (Eg. haylage plus silage) or feed a TMR
  
• Have fresh feed available in bunks or mangers after milking time
  
• Adapt feeding strategies to the eating behaviour of your cows
  
• Feed forages several times and TMR's at least twice daily
  
• Sweep feed up to tied cows frequently
  
• Clean mangers and bunks daily especially in hot weather
  
• Clean water bowls and troughs frequently
  
• Provide at least 60 cm (2 feet) of bunk space per cow
  
• Allow cows access to feed for at least 22 hours of the day
  
• Healthy, contented cows eat more feed
  
• Frequent foot trimming will improve cow mobility and intake
  

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