Morgan on
Ag Issues Program


Chicken Cancer Restricts Production
October 30, 1998
By Thomas H. Morgan
Morgan Consulting Group, Ltd.

Per capita consumption of broiler chickens is expected to be down two percent in 1998 and up only one percent in 1999. This is deviation from the long term trend of increasing broiler chicken production is the result of an epidemic in a relatively new form of avian leukosis virus that is causing a cancer in broiler chickens.

The history of the avian leukosis virus extents back to 1939 when a lab was set up in the U.S. to try to identify a disease in layer chickens. In 1940, it was identified as avian leukosis. Since then five subgroups labeled A through E were identified. Test were developed to identify the disease and control methods including vaccinations were developed.

In 1989, a new subgroup which was labeled avian leukosis virus - subgroup J (ALV-J) was identified in England. This virus was subsequently identified in the U.S. in 1994. By 1996, some poultry scientists were considering it at epidemic proportions. This new strain is particularly a problem since there is a wide variation in its composition among the various samples collected. This makes it more difficult to identify with standardized tests and more difficult to develop a vaccine to control it.

The new strain - Avian Leukosis Virus Subgroup J (ALV-J) - attacks red blood cells in the bone marrow, resulting in tumors of the bones, liver, spleen and kidneys.

The virus spreads both vertically through the breeding stock to the eggs and horizontally from infected to susceptible chickens. Meat strains (broiler chickens) are particularly susceptible.

At present, tumors have been mainly detected in broiler breeder parent stock from known primary breeder contamination, resulting in excessive mortality, increased incidents of other diseases and adverse effects on production and hatchability.

In the U.S., there are suggestions of up to eight percent mortality per month in severely affected breeder flocks. This has resulted in shortages of breeding stock and limiting the supply of broiler chickens. One poultry market analyst reported spot shortages of foodservice broiler chickens.

Gregorio Rosales, president of the U.S. Primary Breeders Veterinary Roundtable says that losses of breeder birds in the most severe cases has reached 20 to 40 percent. He said that the threat to breeding companies is enormous. According to Rosales, "If a producer goes out of business, a gene poll assembled over many years of breeding is lost. And this would be a serious loss, since there are no more than eight major breeding firms in the world."

Rosales states, "Myeloid leukosis is probably the biggest threat to the broiler industry worldwide at the moment."

Presently, ALV-J is affecting both the size of the primary breeder flocks (in cattle terms the seedstock herd) and the broiler breeder flock (in cattle terms the beef cow herd). Originally, it was thought that the broiler themselves were not being affected by ALV-J, but some producers and scientists believe it is also affecting broiler growth and mortality.

The threat to the primary breeder flock has two economic costs. If ALV-J impact becomes large enough it could wipe out whole flocks and cause the loss of expensive genetic material. However, the immediate impact is to limit the size of the primary breeder flock which in turn limits the size of broiler breeder flock as well as infects the broiler breeder flock.

The infection of the broiler breeder flock with ALV-J increasing mortality further restricting the size of this flock and the number of eggs produced. ALV-J may also be reducing the hatchability of these eggs. The fewer broiler eggs and reduced hatchability limit the number of broiler chickens that can be placed into grower houses which in turn limits broiler chicken production. Additionally, further limitations on production maybe occurring as the disease may be reaching the point that it is affecting the growth and mortality of broiler chickens.

So far, the scientists have yet to produce a satisfactory testing protocol to identify infected birds or a vaccine to immune chickens. This combined with the virus’ penchant to be more virulent than the previous five subgroups, implies that the epidemic may get worse before control methods are developed and deployed to reduce the diseases impact.

Consequently, broiler production will likely be greatly constrained in the coming year in spite of very low feed costs and high broiler chicken prices.

The broiler breeder flock grew at the rate of eight percent in 1994 and 1995, before ALV-J hit at epidemic proportions. In 1996 and 1997, the flock grew at only two percent. The flock is expected to increase by only three percent in 1998 and 1999, in spite of the lower feed costs and high broiler prices.

When the other production factors are taken into consideration, broiler chicken production is expected to be up only one percent in 1998 and increase of by only two percent in 1999. Per capita consumption is expected to be down two percent in 1998 and increase by one percent in 1999. This is far below the long term trend.

 

Flock

Hatchings

Slaughter

Live Wt

Production

Exports

Consump

Year

1,000

%

mln

%

mln

%

lbs

%

mln

%

mln

%

lbs

%

1994

44,763

108

7,548

106

7,072

106

4.63

102

23,546

108

2,875

146

81

102

1995

48,472

108

7,925

105

7,375

104

4.66

101

25,025

105

3,894

136

81

100

1996

49,390

102

8,078

102

7,546

102

4.78

102

26,336

105

4,420

114

82

102

1997

50,172

102

8,322

103

7,736

102

4.81

101

27,271

104

4,681

106

84

103

1998

51,824

103

8,470

102

7,800

101

4.85

101

27,616

101

5,150

110

83

98

1999

53,638

103

8,647

102

7,886

101

4.90

101

28,208

102

5,250

102

84

101

The potential threat of this disease to the broiler chicken industry, as identified above by Rosales, points out a weakness in the much hailed concentrated and vertically integrated chicken industry.

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thmorgan@morgan-consulting.com

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