By David Jones, Ph.D., P.A.S.
Preparing pre-fresh cows to properly transition from the dry period to lactation is instrumental to the success of the cows once they freshen and begin lactation. Some basic goals when preparing pre-fresh cows to transition to lactation are:
- Maximize DMI before and after calving
- Maintain immune function
- Minimize body fat mobilization around calving
- Maintain blood calcium and magnesium concentrations at and after calving
Several common problems occur if the cow does not transition properly:
- Sub-clinical or clinical hypocalcemia (milk fever)
- Displaced abomasum (DA)
- Retained placenta (RP)
- Dystocia (difficult calving)
- Metritis (uterine infection)
- Decreased fertility
Sub-clinical hypocalcemia may be the leading issue predisposing cows to DA, RP or ketosis after freshening. Sub-clinical hypocalcemia will lead to reduced dry matter intake (DMI) at a time when DMI is at its lowest, which will increase body condition loss after calving.
Balancing pre-fresh diets is one aspect of pre-fresh cow management that can minimize problems after calving. Dietary calcium of pre-fresh diets should be maintained between 100 and 180 grams per cow per day. However, the calcium that can be obtained from the bones is the most important calcium for preventing hypocalcemia and other metabolic issues at calving. One important aspect of a pre-fresh cow diet is the pre-fresh cow index (PCI) which is Agri-King’s version of the dietary cation anion difference (DCAD). The PCI should be balanced according to the following ranges prior to calving:
- Pre-fresh cows: +400 to +500 (U.S.A.)
- Pre-fresh cows: +500 to +600 (Ireland, United Kingdom)
These ranges are simply guidelines and can be modified on an individual farm basis. The goal with adjusting the PCI is to create a diet that will acidify the blood and cause the urine pH to be between 5.5 and 6.5. This pH range tells us we have successfully put the pre-fresh cows in a controlled state of metabolic acidosis which forces calcium to be released (in the form of calcium carbonate) from the bones. The carbonate fraction will buffer the acids in the blood and the free calcium can be used by the cow to prevent milk fever and other metabolic issues. Monitoring urine pH with pH strips or pH meters is a very important part of pre-fresh cow management. Once the cow has freshened a diet needs to be fed that won’t cause a controlled metabolic acidosis so the acidify effect on the blood can be reversed and calcium will no longer be released from the bones.
Phosphorus and magnesium also are very important for proper transition from the dry period to lactation. Low phosphorus and magnesium will lead to down cows at freshening which looks very similar to milk fever. Phosphorus is required for the generation of energy and magnesium is required for muscle contraction. Maintaining dietary phosphorus between 40 and 50 grams per day and magnesium around 0.4% of diet dry matter is important.
Vitamin E is a critical nutrient in every pre-fresh ration. The transition period is the most stressful time in a cow’s lactation cycle and DMI is at its lowest point. There is research documenting higher concentrations of vitamin E administered to pre-fresh cows (1000 to 4000 IU/d of supplemental vitamin E) to improve performance and health. Today 2000 to 3000 IU of vitamin E in the pre-fresh ration is thought to be enough because dietary selenium has been increased to 0.3 ppm compared to 0.1 ppm at the time initial vitamin E research was conducted. The use of Agri-King’s Dry Cow Micro Pak, in combination with Super MIcro, will accomplish the goal of increasing vitamin E in the pre-fresh diet. Because the transition period includes the first 21 days after calving Agri-King’s new AK Bovine REPLETE should be used in post–fresh cow diets to maintain elevated vitamin E concentrations, although lower than the pre-fresh ration, at a time when DMI is still reduced, but starting to increase.
Dietary starch concentration is often overlooked, especially with high straw pre-fresh diets. Starch promotes ruminal propionate production which, in turn triggers the release of insulin that will help limit body fat mobilization. Increasing starch in the pre-fresh diet also tends to stimulate increased DMI. Pre-fresh cows will transition to a post-fresh or high group ration which will have a starch concentration somewhere between 23 and 28% in the U.S.A. and 15 to 20% in Ireland and the UK. Feeding a pre-fresh diet with less than 15% (U.S.A.) or 12% (Ireland/UK) starch and transitioning to the higher starch concentration of a lactation diet may be too large of a jump. This can cause cows to go off feed which will start them down the path of ketosis and DA’s. Consider a stair step approach with starch for transitioning cows to lactation:
- Far off dry cows: 12 to 15% starch (U.S.A.); 6 to 10% starch (Ireland/UK)
- Pre-fresh cows: 18 to 23% starch (U.S.A.); 12 to 15% starch (Ireland/UK)
- Early lactation: 23 to 28% starch (U.S.A.); 15 to 20% starch (Ireland/UK)
This approach will help adjust the rumen microorganisms to starch concentration as we move the cows toward calving. Of course, we must watch the energy concentration of the ration as we include starch. Too much energy in the diet at calving also can cause cows to have reduced DMI.
Straw (upwards of 11 lbs per cow per day) is often recommended in pre-fresh diets. Straw has its place, but is likely over used in current pre-fresh ration programs. The concept with straw is to lower the energy concentration of the ration so pre-fresh cows increase their DMI. Straw will also lower potassium concentrations in the pre-fresh ration which will lower the PCI. These concepts are true until too much straw is fed. Issues with too much straw (greater than 5 lbs per day):
- Gut fill preventing the desired increase in DMI
- Low dietary energy leading to increased body fat mobilization after calving (if DMI did not increase)
- Lower dietary potassium (below the requirements of the pre-fresh cow. Dietary potassium should not go below 1% and 1.2% to 1.5% potassium is an ideal range)
- Chop length is too long (longer than 2 inches) allowing pre-fresh cows to sort the feedstuffs
There are some benefits to straw (5 lbs or less per day):
- Reduced dietary energy leading to improved DMI (energy still needs to meet the pre-fresh cows requirement)
- Lower potassium causing a reduction in PCI without the use of anionic salts (potassium must meet the pre-fresh cows requirement)
It should be noted that other lower quality forages (on an energy basis) can be used in place of straw, such as, grass hay.
Properly transitioning a pre-fresh cow through calving and into lactation requires some of the most important (if not most important) dietary management throughout the lactation cycle. Using the Agri-King program can improve the transition of pre-fresh cows to lactation. The Agri-King program will properly balance PCI, starch and energy, as well as, supplement proper fortification through the use of Dry Cow Micro Pak, Super Micro, and AK Bovine REPLETE. Contact your local Agri-King Area Manager who will assist in the management of this critical period in the cow’s cycle. AK
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