| |
4Livestock-Poultry
Science and technology have made for great expansion of the
poultry industry in recent years. Current world average
expansion of egg production is 3 to 4 % annually. Most nutrition
programs can be improved by the inclusion of eggs and / or
poultry meat. Poultry products are of the highest nutritional
quality. |
| |
| |
|
| |
News Channel |
| |
July 2004 |
| |
|
| |
Scientists
unlock secret of deadly Spanish Flu.
A team of British scientists has revealed how a bird flu virus
that emerged in 1918 became the most deadly infection in
history.
The lethal turning point came when the Spanish Flu virus altered
its surface structure, making it capable of infecting humans as
well as birds.
It went on to sweep rapidly across the world, felling young
people in their prime and claiming up to 50 million lives.
Experts monitoring the current outbreaks of avian, or bird flu,
in Asia are terrified of a similar pandemic occurring again.
The World Health Organisation has recorded 15 human deaths so
far in Vietnam and Thailand. However, the virus does not seem to
be passing from person to person.
A team of British scientists has described for the first time
the three-dimensional shape of the 1918 virus's most potent
weapon - proteins that dot its surface and allow it to invade
cells.
The spike-like hemagglutinins (HA) lock onto particular receptor
molecules on the surface of cells in the lungs. Until now the
true nature of these all important proteins was unknown.
Sir John Skehel and colleagues at the Medical Research Council's
national Institute for Medical Research - where the first human
influenza virus was identified in 1933 - studied genetic
material from samples taken from Spanish Flu victims in the
United States.
Using a technique called X-ray crystallography, they worked out
the virus's HA structure and saw that it had mutated.
Human and avian virus hemagglutinins normally interact with
different cell receptors, making it difficult for bird flu to
infect people. But the 1918 virus HA had changed, making it able
to attach either to bird or human cells and allowing rapid
human-to-human transmission.
Because immune systems were not adapted to bird flu the virus
proved exceptionally deadly, wiping out up to 70 per cent of
victims in some communities, including many people aged 15 to
34.
Sir John, whose findings were reported in the journal Science,
said, "This paper is important because of the knowledge it
brings about how these viruses, which originate in birds, can
jump to humans. This allows us to track and monitor the changes
in the virus for public health purposes, even though it does not
allow us to predict or prevent future forms of flu."
An American group writing in Science also reported work on the
virus. The team led by Professor Ian Wilson, from the Scripps
Research Institute in San Diego, California, determined the
structure of the precursor protein that becomes HA.
The US researchers also found evidence of the way the binding
molecules were designed to interact with human proteins.
They compared the 1918 virus to others that normally infect
humans, birds and pigs.
Professor Wilson said, "It looks more like an avian virus - with
some human characteristics."
All the worst human flu outbreaks of the 20th century were
caused by viruses that came from birds.
The most devastating was the Spanish Flu pandemic of 1918, but
Asian Flu in 1957 and Hong Kong Flu in 1968 also claimed many
lives.
Sir John pointed out that the bird flu virus now causing concern
in Vietnam, Thailand and China was not the same as the one
responsible for the 1918 pandemic. It had a form of
hemagglutinin known as H5, whereas the 1918 virus was an H1
strain.
While the new work helped scientists know more about the
transmission of infections from birds to humans, "it will not
have an immediate impact on the situation currently unfolding in
the Far East", he said.
Scientists hope to improve their understanding of the 1918
pandemic still further by exhuming the body of a 20-year-old
British victim.
Phyllis Burn, an Army officer's daughter was buried in a
cemetery in Twickenham, south of London, 85 years ago.
She was laid to rest in a lead coffin which, if properly sealed,
would have been virtually airtight. Scientists hope her internal
organs may be sufficiently preserved to allow tissue samples to
be taken from her lungs.
Fresh bird
flu outbreak kills 5,000 fowls in Vietnam
Bird flu has
recurred in Vietnam, killing about 5,000 fowls, an official told
Xinhua Wednesday.
"Tests conducted in the regional veterinary centre in Ho Chi
Minh City have confirmed that all the fowls were tested positive
for an H5 strain of bird flu," said Nguyen Phuc Tai, director of
the veterinary department of Bac Lieu province.
The fowls from two farms and a household have died since June
25, he said, adding that the province has culled all of the
infected fowls in an effort to contain the virus.
Reasons for the bird flu's return in the locality are being
studied, Tai said.
To deal with the current situation, Bac Lieu will re-establish a
steering committee on bird flu and tighten controls.
In Bac Lieu province, which has a poultry population of 1.4
million, nearly 900,000 fowls died or were culled during the
bird flu outbreak earlier this year.
Vietnam was reported to face a high risk of the relapse of bird
flu last week as 13 localities in the country still had avian
influenza viruses, mainly in ducks.
The government has allowed the Ministry of Agriculture and Rural
Development to conduct a $7.6 million project to overcome the
aftermath of the bird flu outbreak.
Bird flu
mutating into deadlier threat: study
A frightening strain
of bird flu that can kill people is mutating into an ever more
deadly form in ducks and needs to be controlled quickly, US and
Chinese researchers have reported.
They found steady changes in the so-called H5N1 virus infecting
flocks of apparently healthy ducks made the virus more likely to
kill mammals such as mice and perhaps people.
"Our findings suggest that immediate action is needed to prevent
the transmission of highly pathogenic avian influenza viruses
from the apparently healthy ducks into chickens or mammalian
hosts," the researchers write in this week's issue of the
Proceedings of the National Academy of Sciences.
The H5N1 virus was first seen in Hong Kong in 1997 and has
reappeared in South East Asia, killing 24 people in Vietnam and
Thailand this year.
Whenever it appears in poultry, officials move quickly to
destroy the birds to prevent its spread.
Unlike ordinary influenza, so far H5N1 cannot be spread from
person to person, so it does not cause human epidemics.
But flu experts say the virus, which mutates quickly, could
acquire this ability at any time.
Hualan Chen of the Harbin Veterinary Research Institute and
colleagues analysed 21 different samples of the H5N1 bird flu
virus taken from healthy flocks of ducks in southern China
between 1999 and 2002.
They inoculated groups of chickens, mice, and ducks with virus
samples taken in different years.
The ducks never got sick, but most of the virus samples made
chickens ill and killed them.
The key issue is mice, which are mammals like humans and more
likely to react as humans do.
"We observed an increasing level of pathogenicity to mice with
the progression of time," the researchers wrote.
"Viruses isolated in 1999 and 2000 were less pathogenic (deadly)
to mice than those isolated in 2001 and 2002," they added.
They found some expected changes in genes associated with how
deadly a virus is and said their findings suggest the virus is
evolving.
To date more than 100 million birds have been culled or have
died from bird flu, which experts suspect was spread across Asia
by migratory birds or wild fowl.
Different strains are infecting flocks around the world but the
H5N1 strain is the one that most worries health experts
Certain
antibiotics may rapidly contaminate egg albumen during the
process of its formation.
Egg white
formation occurs in 3 phases: synthesis and storage of albumen
proteins prior to ovulation, secretion of proteins during
passage of the ovum down the reproductive tract (preplumping)
and addition of water (plumping phase). 2. This study was to
determine if oxytetracycline would transfer into egg albumen
during the latter 2 phases of albumen formation. 3. In 2
experiments 48 hens were injected with either 400 mg/kg
oxytetracycline or physiological saline. Hens were dosed at 0·5
h (preplumping phase) or 5·5 h (plumping phase) after
oviposition. 4. Five hours following injections, hens were
euthanised and albumen was collected from the reproductive
tract. 5. Oxytetracycline transferred into albumen during both
phases of albumen formation. Concentrations (ppm) were greater
in the preplump vs plump phase (3·2 vs 1·8 in experiment 1; or
2·8 vs 1·6 in experiment 2. However, when differences in albumen
weights were accounted for, total ΅g transfer did not differ
between the 2 phases. 6. Drugs may transfer into egg whites
during the latter phases of formation prior to oviposition.
Therefore, poultry producers or veterinary practitioners dosing
laying hens must consider that egg whites contained in the 1st
egg laid after dosing may contain drug residues.
Effect of
Lactose and Dried Whey Supplementation on Growth Performance and
Histology of the Immune System in Broilers.
The objective of
this study was to evaluate the effect of lactose and dried whey
supplementation as dietary component on growth performance and
histology of lymphoid organs and ileum in broilers. A total of
480 day-old chicks were utilised for 42 days. Animals were
assigned randomly to one of three treatments: control, lactose
(2.5%), and dried whey (3.85%). Body weight was greater for
animals supplemented with lactose or dried whey than for those
not supplemented. There were no effects of treatments on feed
intake and feed efficiency. In general, the effects of lactose
or dried whey supplementation on histology of lymphoid organs
and ileum were variable. Plasma cell counts were lower for
animals supplemented with lactose than for those supplemented
with dried whey. However, the length of intestinal villi during
the starter period was greater for experimental groups than for
control group.
Stiffer
Protein Rules
Canadian food
safety officials are said to be considering a total ban on
ruminant protein cattle and sheep from all livestock feed.
Some researchers believe that bovine spongiform encephalopathy
is spread from animal to animal through abnormal proteins
prions in the feed. The prions contaminate the feed when
ruminant protein meat and bone byproduct meal is mixed in
feed as a protein source.
Ruminant protein has been banned from cattle and sheep feed in
Canada and the United States since 1997. Currently in Canada
as well as in the United States feed manufacturers and
livestock producers can feed rations containing ruminant protein
to non-ruminants mainly pigs and poultry. However, there are
fears that pig and poultry feed containing ruminant protein
could be accidentally fed to cattle or sheep of poultry litter
containing spilled poultry feed could be fed to cattle or sheep
and spread the disease.
Brian Evans, chief veterinarian with the Canadian Food
Inspection Agency.said the proposed ban on feeding ruminant
protein to swine and poultry is part of the Agencys efforts to
ensure any lingering cases of BSE are eliminated from the
domestic cattle herd. Our current feed ban is sound, Evans
said.
The discussion of an extended feed ban is part of consultations
that CFIA is conducting with provincial governments and USDA on
steps the two countries can take to strengthen the BSE
prevention aspects of feed regulations. CFIA spokesman Jeff
Meerman told MeatNews that the proposed ban is only one option
that the Agency is considering as a tool for stopping the spread
of BSE and to allay foreign market fears of the brain-wasting
disease. He added that any decision will be based on the current
science and practicality. One potential problem if Canada
extends the ban and the United States doesnt is the movement of
cattle offal to U.S. rendering plants. Some offal contains
high-risk material such as brains, spinal cords, and lymph
tissue. Currently, rules enacted after Canada discovered its
first case of BSE in May 2003 ban Canadian beef offal from being
exported to the U.S.
Officials are also looking at barring the use of cattle brain
and nerve system tissue in swine and poultry feeds. The
discussions between CFIA and USDA are in advance of a new
international code of practice for livestock feeding being
developed by OIE, the international veterinary organization
Is it safe to
eat poultry from areas affected by avian influenza?
There is no public
health risk associated with the consumption of cooked poultry
meat or eggs as a result of these cases.
Health Canada advises that poultry products and eggs from areas
experiencing an outbreak of avian flu do not pose a risk to
human health for avian flu. The virus is known to be killed at
temperatures above 72ΊC, however, Health Canada recommends
cooking whole poultry to 85ΊC and other poultry products and
eggs to 74ΊC to ensure microbial food safety.
What is avian influenza?
Avian influenza is a contagious viral infection that can affect
all species of birds (chickens, turkeys, guinea fowl, pet birds
and wild birds). In intensive poultry rearing systems, young
fattening turkeys and laying hens are usually the most affected
species.
Wild birds may carry influenza viruses without becoming ill due
to natural resistance. Wild waterfowl present a natural
reservoir for these viruses and can be responsible for the
primary introduction of infection into domestic poultry. Signs
of the disease range from a mild infection with no symptoms to a
severe epidemic that kills up to 100 percent of infected birds.
Is avian influenza transmissible to humans?
In rare instances people can contract avian flu. To date, the
H5N1, H7N7 and H9N2 subtypes of the avian influenza virus have
been known to cause illness in people, with H5N1 associated with
the most serious illness in humans.
To date, two people have been infected with avian influenza.
Both cases of infection followed close contact with infected
poultry and contaminated materials and resulted in mild
symptoms. Both people have fully recovered.
Are more cases of human illness possible?
The culling operation in British Columbia (Canada) is an
extensive one so it is likely that we'll see more confirmed
infections. Given this possibility, antiviral drugs are
recommended for workers in contact with infected chickens or
contaminated materials. Health Canada has provided occupational
health and safety advice to the CFIA. Currently, workers must
have received the current flu vaccine and antivirals and
training on the use of personal protective equipment before
working with the high risk flocks.
Has the H7 virus ever infected humans?
Most recently, the H7N2 virus was detected in poultry in
Delaware and did not cause illness in humans. An outbreak of
H7N7 in the Netherlands in 2003 resulted in one death and over
80 cases of mild disease in people. The vast majority of these
cases exhibited conjunctivitis, and some of them displayed mild
influenza-like illness.
-----------------------
Dr.Habib-ur-Rehman
Senior Farm Manager
Olympia Poultry Farms
Abbotabad
habna@brain.net.pk
0992 370465 |
|
|
