Dairy Cow Nutrition on different Lactation Cycles

Find all Abbreviations used at the end of the article

Nutrient requirements vary with the stage of lactation and gestation. Five distinct feeding phases can be defined to attain optimum production, reproduction and health of dairy cows:

• Early lactation: 0 to 70 days (peak milk production) after calving (postpartum).
• Peak Dry Matter intake: 70 to 140 days (declining milk production) postpartum.
• Mid- and late lactation: 140 to 305 days (declining milk production) postpartum.
• Dry period: 60 to 14 days before the next lactation.
• Transition or close-up period: 14 days before calf down.

Phase 1: Early lactation: 0 to 70 days after calving down. 

Milk production increases rapidly during this period, peaking 6 to 8 weeks after calving. Feed intake does not keep pace with nutrient needs for milk production, especially for energy, and body tissue will be mobilized to meet energy requirements for milk production. Adjusting the cow to the milking ratio is an important management practice during early lactation. Increasing grain by about ½ kg daily after calving will increase nutrient intake while minimizing off-feed problems and acidosis. Excessive levels of grain (over 60% of the total Dry matter) can cause acidosis and a low milk fat percentage. The fibre level in the total ration should not be less than 18% ADF, and 28% NDF. Forage should provide at least 21 percentage units of NDF or about 75% of the total NDF in the ration.

Protein is a critical nutrient during early lactation. Meeting or exceeding crude protein requirements during this period helps stimulate feed intake and permits efficient use of mobilized body tissue for milk production. Rations may need to contain 19% or more crude protein to meet requirements during this period. The type of protein (degradable or undegradable) and amount of protein to be fed will depend on the ration ingredients, method of feeding, and milk production potential of the cow.

To increase nutrient intake:

• Feed top-quality forage
• Ensure the diet contains adequate amounts of CP, DIP and UIP
• Increase grain intake at a constant rate after calving
• Consider adding fat (0.35 to 0.5 kg/cow/day) to diets
• Allow constant access to feed
• Minimize stress conditions.

Phase 2: Peak DM intake: second 10 weeks after calving down. 

Cows should be maintained at peak production for as long as possible. Feed intake is near maximum and can supply nutrient needs. Cows should no longer be losing body weight and either maintaining or slightly gaining weight.

Grain intake can reach but should not exceed 2.5% of the cow’s body weight (600 kg cow can consume up to 7 kg of DM from grain). Adding grains or feeds high in digestible fibre to the ration may be necessary to help maintain an optimal rumen environment when these high levels (55 to 60% of the ration DM) of grain are being fed. In general, rations should not contain more than 40% NFC. Forage quality should still be high with intakes of at least 1.5% of the cow’s body weight (DM basis) to maintain rumen function and normal fat test. Potential problems during this period include a rapid drop or decline in milk production, low-fat test, silent heat (no observed heat), and ketosis.

To maximize nutrient intake:

1. Feed forages and grain several times a day.
2. Feed the highest quality feeds available.
3. Limit urea to 100 grams per cow per day.
4. Continue to minimize stress conditions.

Phase 3: Mid- to late lactation: 140 to 305 days after calving down. 

This phase is the easiest to manage. Milk production is declining, the cow is pregnant, and nutrient intake easily meets or exceeds requirements. Grain feeding should be at a level to meet milk production requirements and begin to replace body weight lost during early lactation. Lactating cows require less feed to replace a pound of body tissue than dry cows. Young cows should receive additional nutrients for growth (2-year-old, 20% more; 3-year-old, 10% more than maintenance). Consider NPN as a source of supplemental protein. Potential problems during this phase are few.

Milk production should slowly decline at an 8 to 10% drop per month. Avoid over-conditioning cows.

Salt: 0.5% of the ration DM or 1% of the grain mix.

Mineral: Approximately 1% of the grain mix should be a calcium-phosphorus mineral.

Urea: Maximum of 200 grams of urea per day or 1% of the grain mix.

Vitamins: Supplemented A, D, and E in rations to meet requirements.

Ration form: Forages and grains should not be chopped or ground too fine.

Phase 4: Dry period: 60 to 14 days before calf down. 

The dry period is a critical phase of the lactation cycle. A good, sound dry cow program can increase milk yield during the following lactation and minimize metabolic problems at or immediately following calving. The optimum dry period length will vary from animal to animal, but generally, it is recommended to be between 45 to 60 days. Dry periods of less than 45 days and longer than 60 days result in lower milk production during the next lactation. Short dry periods do not allow the udder to fully recover, and long dry periods result in over conditioning of dry cows.

A dry cow feeding program separate from lactating cows is required. Diets should be formulated to meet dry cows’ nutrient requirements: body maintenance, fetal growth, and replacing any additional body weight not replaced during phase 3. DM intake will be near 2% of the cow’s body weight. Forage intake should be a minimum of 1% of body weight or 50% of the dietary DM. Grain feeding should be according to needs but not exceeding 1% of body weight. One-half of 1% of body weight in grain fed daily is usually sufficient in most dry cow feeding programs. Limiting the amount of feed DM offered to less than 2% of body weight may be necessary when rations contain only corn silage or other high-energy feeds to avoid over-conditioning cows. Feeding low-quality forages such as maize stalks or grass hay are preferable to limit feeding. If it is necessary to limit feeding, be sure the ration is balanced to supply all nutrients in their correct amounts. A minimum of 12% CP in the DM is recommended.

Meet calcium and phosphorus needs, but avoid large excesses. Calcium intakes of 60 to 80 grams and phosphorus intakes of 30 to 40 grams are sufficient for most cows. Dry cow rations above 0.6% calcium and 0.4% phosphorus (DM basis) increase milk fever problems. Provide adequate amounts of vitamins A, D, and E in rations to improve calf survival and lower retained placenta and milk fever problems. Trace minerals, including selenium for most producers, should be adequately supplemented in dry cow diets.

Problems such as milk fever, displaced abomasum, retained placenta, fatty liver syndrome, fatty liver formation, poor appetite, and other metabolic disorders and diseases are common in fat cows at freshening.

Key management factors are normally observing the body condition of dry cows and adjusting energy feeding as necessary. Meeting nutrient requirements and avoiding excessive feeding. Changing to a transition ration starting 2 weeks before calving.

Avoiding excess calcium and phosphorus intake. Limiting salt to 300 grams and limiting other sodium-based minerals in the dry cow ration to reduce udder oedema problems.

Phase 5: Transition period: 14 days before calf down.

The transition or close-up dry cow feeding program is critical to adjusting dry cows and springing heifers to the lactation ration and preventing metabolic problems. Some grain, if not previously fed, should be fed starting two weeks before freshening. The introduction of grain is necessary to begin changing the rumen bacteria population from an all-forage digestion population to a mixed population of forage and grain digesters. Adding some ingredients used in the lactation ration during this period minimizes the stress of ration changes after calving. Some suggested management strategies during this period include:

Providing 2.5 to 435 kgs of grain to adapt rumen microbes to fermentable carbohydrates and stimulate rumen papilla formation. The added grain sources are fed individually or as part of a lactating TMR.

Increase protein in the ration to between 14 and 15% of the ration DM. Feeding some of this additional protein in the form of the undegradable protein may be beneficial in supplying amino acids for foetal growth.

Limit fat in the ration to 100 grams. High-fat feeding will depress DM intake.

Maintain 2.7 to 4.5 kgs of long hay in the ration to stimulate rumination. If maize silage or lactation TMR is fed, limit DM amounts to 1% of body weight.

Abbreviations:

DM = dry matter RFV = relative feed value

DMI = dry matter intake UIP = undegradable intake of protein

CP = crude protein DIP = degradable intake protein

NFC = non-fibre carbohydrates SIP = soluble intake protein

ADF = acid detergent fibre NPN = Non-protein nitrogen

NDF = neutral detergent fibre