When a cow freshens, a dramatic metamorphosis occurs. Consider the changes a cow experiences:
- The udder is transformed from a non-productive flap of skin to a secretory factory.
- The rumen changes from a forage fermentation vat to a cauldron of concentrate soup.
- The abdominal contents change by 150 pounds in minutes.
- The metabolic rate changes dramatically. A dry cow has about 3 grams of calcium in her bloodstream at any given time. In the early post-partum period, a dairy cow turns over that 3 grams to make calcium for milk about five to six times each day.
- When rations contain adequate effective fiber, she secretes about 6 pounds per day of bicarbonate in her saliva through chewing.
- Even more amazingly, she turns over blood sugar every five minutes.
In human terms, your cow moves from a "couch potato" to a milking "athlete" at freshening. If all goes well, she uses more energy daily - compared to maintainance requirements - than a marathon runner uses in a 26-mile run.
During this critical period, you should develop a "zero tolerance" for problems. A dairy producer once told me his goal for dead-on-arrival calves was zero, unless the calf was positioned improperly. Having that goal, he worked to prevent calf loss at every opportunity. I think we should take the same approach with the transition cow. A smooth transition from the dry period to lactation occurs when an animal calves and returns to production without clinical or subclinical disease, including dystocia. There is no physiological reason for metabolic disease to occur in healthy animals.
Economics provide an extra incentive for eliminating problems in the transition period. When cows freshen, studies show that the risk of death and disease increase 10-fold compared to the rest of the lactation. In a typical herd, 90 percent of all treatment expenses are incurred during the first three weeks after calving. And most clinical mastitis occurs in early lactation as a result of infections acquired during the dry period.
In addition, poor management of problems during the transition period causes low milk production, poor feed efficiency and decreased fertility. For example, the low calcium levels that result in milk fever also decrease rumen motility, which can lead to a displaced abomasum. And, low calcium levels decrease uterine muscle contractions, resulting in metritis and retained placenta.
Furthermore, cows that suffer from a severe negative energy balance can be infertile for two months after they recover. If poor feed consumption leads to rumen acidosis, the effects can last for months. Acidosis results in a lower feed intake, a decrease in butterfat production and re-duced feed efficiency. Ad-ditionally, severe rumen acidosis can result in lami-nitis and sole abcesses for several months after the nutritional insult.
By developing a zero tolerance for disease in the transition period, you can optimize performance for the rest of the lactation. To quote another producer, "Once you get her past the first two weeks, the rest is easy."
Marguerita B. Cattell is a consulting veterinarian in Loveland, Colo.
Calculating the cost of the transition period
If the dry cows and fresh cows were treated as separate business entities, how many days would it take for a fresh cow to pay for the expenses incurred during the dry period?
Use the following example for Cattell Dairy as a guide to calculate your pay-back time or break-even time. A break- even of less than 10 days is excellent, between 10 to 20 days is good, and a break-even beyond 20 days needs attention.
Step 1: Calculate your expenses:
Expenses = Feed cost in dry period + average post-partum disease treatment cost + average labor cost in sick cow/maternity area
(61 average days dry x $1.25 feed cost per day) + ($15) + ($64) = $155.25 per cow cost for dry and transition period.
Step 2: Subtract the value of calf income:
Calf income = (average value of calf x calf survivability rate)
($65 x 0.95) = $61.75
Therefore: $155.25 - $61.75 = $93.50
Step 3: Calculate the days in milk needed to break even:
Average milk production shown at the first test 20 days after freshening is 60 pounds per day. Average daily income from milk production equals: 0.60 hundredweights X $15 per hundredweight =$9 a day.
$93.5/$9 = 10.4 days to break-even