New Bolton research probes dairy mysteries
BY JACK HUBLEY
KENNETT SQUARE -
Traveling through the
undulating Chester County
farm country, this place
leaps out at you like a castle
in a desert. New Bolton
Center, with its 1,000-acre
campus and 70 buildings,
reminds you that there’s
more to Kennett Square
than mushrooms.
New Bolton is the
University of Pennsylvania
School of Veterinary
Dr. Robert Whitlock exams test tubes con
taining incubating cultures of Johne's disease
bacteria.
Johne’s Disease
The year was 1895 when Doctors Johne and
Frothingham discovered the cause of the disease that
would bear the former scientist’s name.
And 90 years later, an effective weapon to combat an
organism known as Mycobacterium paratubarcuhsis has yet to
be found, as researchers continue to grapple with Johne’s
disease.
The trouble starts when bacteria enter the cow’s in
testinal tract and begin to multiply. The host responds by
manufacturing more-disease fighting cells in the in
testine. This thickens the intestine walls and reduces the
animal’s ability to absorb nutrients.
As a result, the animal loses weight even though food
consumption remains constant. Weight loss and diarrhea
are the most common symptoms of Johne’s, with a
swelling under the jaw (bottle jaw) and watery diarrhea
showing up in the advanced stages.
Calves during their first few weeks of life are most
susceptible to infection, says Dr. Robert Whitlock. Be
even after infection, animals may not develop symptoms
for two to eight years.
For all practical purposes, no cure exists, although
Whitlock points out that some success has been recorded
using an experimental drug used to treat human leprosy.
No meat or milk from animals treated with the drug can
be sold, however, which relegates the treatment to high
priced livestock used only for collecting embryos.
Diagnosing Johne’s can be difficult, since the symptoms
are characteristic of other ailments such as leukemia,
parasites and liver abscesses, notes Dr. Whitlock.
Because of this, little data was available on just how
pervasive the Johne’s problem was in Pennsylvania.
To answer this question, technicians sampled more than
1,400 cattle at the Taylor Packing Company in Wyalusing,
during a one-year period beginning in October IJB3.
Based on the results of this study, New Bolton resear
chers estimate that 42,000 of the state’s 700,000 dairy cows
are Johne’s victims.
Since animals testing positive for the disease averaged
112 pounds lighter than others, economic losses dqe to
weight loss at slaughter can be considered substantial,
emphasizes Whitlock. Using a live weight beef price of 50
cents per pound-or about $55 per ammal-Dr. Whitlock
estimates that Johne’s is costing the state’s cattlemen and
dairymen between one and three million dollars annually.
“We now have very good evidence that Johne’s is
relatively common in the state, and it causes a significant
economic loss that needs to be addressed,” Whitlock
concludes.
Ongoing economic studies may quantify milk
production and genetic potential losses, as well. .
Medicine’s large animal
facility. And though the
school aims to turn out top
flight veterinary students,
its mission goes far beyond
that of education, says New
Bolton’s associate dean,
Dick McFeely.
Strategically located
within the state’s in
tensively farmed
southeastern region, the
center services animal
agriculture with its hospital
and lab facilities. And
though the center has
become a focal point for the
treatment of equine
ailments, McFeely points
out that more than 3,600
house calls were logged last
year for treating food
animals.
Generating new
knowledge through
research is New Bolton’s
third mission. And, with
financial assistance from
the U.S. and Pennsylvania
Because of the problems associated with diagnosis,
research is also underway to develop a definitive
diagnostic test. Though fecal culture testmg has proven
accurate, 14 to 16 weeks are required due to the slow
growing nature of the Johne’s organism. The long lead
time can create quite a bottleneck at the laboratory, and
Whitlock points out that the Pa. Department of
Agriculture’s laboratory in Summerdale is currently
booking Johne’s testing four to six months in advance.
Though tissue tests have proven accurate, surgical
removal of tissue samples is required. Another alter
native, skin testing, has proven to be of little value.
The use of serological tests is currently being explored
at New Bolton Center, and Dr. Whitlock notes that some of
these research findings should be available this summer.
Drs. Bill Chalupa (foreground) and Jim
Ferguson evaluate a dairy ration.
Nutrition and Reproduction
In terms of imput versus production, a dairy cow is
operating at only 25 to 30 percent efficiency, says
professor of nutrition Dr. Bill Chalupa.
Studies in the nutrition section are directed at
developing feeding and management strategies to
maximize production and reproduction efficiency, he
says.
Research in progress at New Bolton involves
•Dietary buffers The goal is to maintain the proper
acid-base balance to increase milk production and fer
tility.
•Dietary fat Studies have shown that adding fat to the
diet can increase milk and fat production, as well as
improve reproductive efficiency.
•Growth hormone Experiments with growth hormone
have yielded the largest milk production responses ever
obtained.
•Estrus detection This remains one of the dairy far
mers biggest problems.
•Dietary protein There’s more to feeding than simply
providing enough protein. Proper amino acid balance is
essential.
Dr. Chalupa lauds farmers for their ability to increase
forage quality, but also, cautions that protein levels can
get out of hand.
“Now it’s not uncommon to find alfalfa haylage at 20 to
25 percent crude protein,” says Chalupa, “and one has to
recognize that tfus protein is very degradable in the
rumen. So you don’t want to add a highly degradable
protein source like soybean meal,” he emphasizes.
Options for the farmer to consider, says Chalupa, in
clude distillers dried grains, dried brewers grams and
com gluten meal.
Researcher Jim Ferguson agrees that farmers can
overdo a good thing.
“As crude protein increases, we increase milk yield,”
says Ferguson, "but we also increase the number of days
open and the number of services per conception.”
Ferguson notes that studies in progress at New Bolton
include a look at two diets, one containing 16.5 percent
protein and a second with a protein content of 21.5 percent.
“Protein is the dairyman’s most expensive feed
ingredient,” emphasizes Ferguson, adding that New
Bolton is committed to devising feeding strategies that
make the most efficient use of the farmer’s investment.
Departments of
Agriculture, the National
Institutes of Health, as well
as corporate and foundation
sponsorship, New Bolton
researchers continue to
seek answers to some of
dairy’s most compelling
questions.
“We’re trying to look at
optimizing production,”
says McFeely, adding that
veterinary medicine has an
important role to play in
combating subclinical
Suffering from botulism, this foal is a patient
in New Bolton’s intensive care unit. Dr. Tom
Divers checks intravenous solutions.
Neonatal Intensive care
Until recently, the high cost of intensive care could only
be justified in the realm of human medicine.
Enter the high-stakes game of embryo transfer, and
intensive care suddenly becomes a veterinary reality.
Three years ago the medical staff at New Bolton
responded to this need by establishing neonatal intensive
care for calves, and the results have been impressive.
According to Dr. Thomas Divers, in the past two years,
38 calves have been treated on an intensive care basis,
and 29 have recovered. Of the 26 “patients” treated for
calf diarrhea-the most common ailment, says Divers-22
have recovered. And four of the six calves treated for
pneumonia have recovered, he notes.
Research in the area of neonatal care has centered
around better methods of feeding, since nutrition is one of
the most critical aspects of treatment. Most calves must
be fed intravenously, Divers points out.
And, in the process of saving valuable animals,
researchers are refining their diagnostic and therapeutic
techniques.
If the disease known as milk fever is caused by a
deficiency in blood calcium, then the obvious solution is to
add calcium to the cow, right?
Well, yes...and no.
Direct intravenous injection of Ca can, indeed, lead to
dramatic results, with some prostrate animals able to
stand up soon after receiving treatment.
But Dr. Ned Moser feels that preventive medicine
makes more sense. And he points out that research at New
Bolton may lead to the right prescription.
“Milk fever is a metabolic disorder in older cows
associated with the time when the cow calves and starts to
make milk,” Moser explains. But the older animal's
metabolism cannot keep up with the increased demand
for calcium. As a result, blood calcium, phosphorus and
magnesium levels all begin to slide, he says.
Victims of milk fever become unsteady and eventually
go down. And the condition is usually fatal if left un
treated, Moser points out.
Two ways to prevent this scenario, Moser says, are to
increase the cow’s ability to utilize Ca in the diet, and to
increase the use of skeletal Ca during the dry period.
“Don’t just put the dry cow out and forget about her,’’
cautions Moser. “She’s a resting player on the bench ”
And Dr. Moser feels that a vitamin D analog-a syn-
disease and its ac
companying loss i r
production.
Much of the research
conducted by the center’s 7fl
scientists is aimed at
plugging profit leaks in
dairy production. And in its
third Dairy Month issue
“Lancaster Farming’*
takes an inside look at New
Bolton’s ongoing research
in the areas leukemia
nutrition, reproduction and
medicine.
5T
s , -. 7
<*!'* *
Milk Fever
(Turn to Page A 33)