July 01, 2000

 

 Shedding light on induced molting

Posted June 15, 2000

 

Induced molting in layer hens, an issue first considered by the House of Delegates last year, will be revisited in Salt Lake City. Resolution 3, submitted by petition of AVMA members and initiated by the Association of Veterinarians for Animal Rights (AVAR), proposes an AVMA position statement opposing this practice.

The proposed position states:

Resolved, that the AVMA opposes induced or forced molting, the process designed to bring an entire flock of hens into a non-laying and oviduct rejuvenation period at the same time, when it causes harm or stress to the birds. Forced molting is a management practice that has been tried using numerous different methods but is generally accomplished through long-term food withdrawal. These methods have historically resulted in severe stress or other detrimental physical injuries to these birds, including a compromised immune system, which creates disease in both the hens and their eggs. It is a management practice used solely to benefit the poultry industry rather than providing any health benefits to birds used for egg-laying purposes.

In 1999 the HOD disapproved a similar resolution submitted by petition that called the practice "inhumane."

To strengthen the AVMA position statement on induced molting, the Executive Board in 1998 had approved amended language, as recommended by the Animal Welfare Committee. The changes included addition of statements that feed restriction should be minimized, and that additional research is needed to improve the welfare aspects of the molting process.

The current AVMA position states:

The process designed to bring the entire flock into a nonlaying and oviduct rejuvenation period (commonly called "induced molting") is a management practice that should be done under careful supervision and control. The once-practiced long-term total feed and water withdrawal that resulted in high levels of mortality is not acceptable. Under no circumstances should water be withheld. A carefully monitored and controlled program that may include reduced photoperiod (day length), controlled caloric intake through dietary restriction, and/or reduction in some nutrients essential to egg production (ie, sodium) is acceptable. Feed restriction should be minimized. Careful monitoring of bird weights and weight loss, mortality, egg production, and behavior are needed to ensure that proper results are achieved humanely. Feather loss (molting) is not a reliable index of the progress and success of a resting and rejuvenation program. The goal is to improve the bird's ability to produce a high-quality egg with a good shell, not to replace the feathers. Additional research is needed to improve the welfare aspects of the molting process.

Recently the induced molting issue came before a state legislature for the first time. On May 3, the California Assembly defeated a measure to prohibit the practice. California is the second largest egg-producing state.

Dr. Holly Cheever
Dr. Holly Cheever

To elucidate their opposite views on this issue, AVAR and the American Association of Avian Pathologists (AAAP) each designated a spokesperson to participate in a debate for JAVMA. Gregg J. Cutler, DVM, MPVM, of Moorpark, Calif, is a private poultry practitioner and consultant to the poultry industry, and past president and alternate delegate representing the AAAP in the AVMA HOD. Holly Cheever, DVM, is a mixed animal practitioner in Voorheesville, NY, an AVAR board member, and AVAR spokesperson for this campaign.

Dr. Gregg J. Cutler
Dr. Gregg J. Cutler

JAVMA: Why did AVAR decide to focus its efforts on getting the AVMA to approve this position? What percentage of petitions did AVMA members return to you?
Cheever: The AVMA is perceived by the public, by industry, and by legislators as expressing our profession's consensus on matters of debate. If the AVMA does not issue a condemnation of any particular debative practice, both industry and government tend to use this lack of condemnation to imply support of the controversial practice.

We sent out about 47,000 copies [of the petition], and 2,300 have been turned over to the AVMA.

JAVMA: Do you find the facts of the resolution to be accurate?
Cutler: Basically I found Resolution 3 fraught with factual errors. Rather than cause bone problems, molting helps to prevent bone problems. The mortality statement [in the background, that 1.5 percent of birds die each year as a direct result of induced molting] does not consider expected mortality or overall flock mortality. Also, this is not purely an economic procedure; the procedure benefits consumers and the environment as well as the birds.
Cheever: With all due respect, our stacks of research papers very much support our statement that bone density and bone health are compromised.
Cutler: I've spent at least the past 20 years of my professional career dedicated to watching and improving chicken health care. The idea that molt causes beaded ribs and fractures is totally erroneous. I have watched literally hundreds of millions of birds be molted and have never seen such a situation.

JAVMA: What about the premise that birds molt and fast naturally, and producers are merely manipulating the flock to coordinate the timing?
Cheever: To compare forced molting to a natural molt is completely inaccurate and really disingenuous. For a battery hen, there are no natural behaviors permitted in their 6.9-inch by 6.9-inch square area, other than eating and eliminating, and this is, of course, a highly social species. So we could argue that there may be very few natural biorhythms left in these animals. Natural molting takes weeks, and it's initiated by a complicated hormonal cascade caused by a gradual decrease in photoperiodicity. It does not, in the natural circumstance, involve a 25 to 35 percent drop in body weight, or total loss of feathers, or total starvation, or the increase in aggression and feather picking and frenetic behavior we see in starved hens; or the pathological findings, including beaded ribs, pathological fractures, extreme weight loss, extreme decrease in liver mass, and particularly the hemorrhagic and ulcerated gastrointestinal tracts we find due to the increase in Salmonella susceptibility, severity, and shedding.
Cutler: If we did not synchronize them, we would not be able to meet their nutrient requirements. Contrary to what Dr. Cheever said, the molt we do really does simulate very closely what happens in nature. It is not a quick molt — what she is referring to is actually that the period of feed withdrawal is quick, but the molt goes on for a total of four to six weeks. This is very similar to what happens when birds are sitting on a clutch of eggs. The bird lays a clutch of eggs, goes out of production, sits on the clutch, then incubates the eggs, and the eggs all hatch together. We also simulate what happens in the fall — we reduce the photoperiod, and we reduce the feed availability, just as it happens in nature.
Cheever: Poultry experts just as renowned as Dr. Cutler, for instance Ian Dunkin, point out that this is nothing like natural molting. I also don't think it's appropriate to compare it to brooding behavior, which is not part of the natural molt.

JAVMA: What about the usual duration of the molt, and whether food and nutrients are completely withheld?
Cutler: Molting [procedures are] based on extensive research over more than 40 years. The length of molt is determined by numerous factors, including the strain of the bird, the weight of the bird at the time of molt, and previous production parameters. Water is never withheld from birds in molt, and feed is restricted for variable time, based on sound research and decades of field experience.
Cheever: United Poultry Concerns did a national poll of producers and found that the length of food withholding varied from seven to 21 days. Ten to 14 days seemed to be the national average. No bird would voluntarily stop eating for that 10- to 14-day period, certainly not for three weeks.

JAVMA: What is your view on the studies linking induced molting and increased susceptibility to Salmonella enteritidis (SE)?
Cutler: Just as Dr. Cheever has indicated, there is the complex hormonal cascade that occurs when the birds go into molt, and similar things happen when they come into production, which is a particularly difficult stress on birds. In all recent prevalence surveys I have reviewed, where virtually all egg-producing premises were surveyed, 90 percent of premises were free of SE. Every premise in California was included in one survey. Also consider that during the molt period, no eggs are being produced, and it is likely that the organism is cleared from the bird before the molt ends.
Cheever: There are so many reports linking increased prevalence of Salmonella enteritidis with the forced molting process that we feel very secure in stressing this as a public health issue as well as an animal welfare issue. The 1995 Pennsylvania pilot project is one of the more recent studies that has enormous value in demonstrating increased public health risks and increased exposure to SE-positive eggs in the force-molted flock. Its conclusion was that postmolt flocks have a higher prevalence of SE-positive eggs than premolts. This higher prevalence occurs primarily during the five-week postmolt period but will last approximately a full 10 weeks postmolt. The increase in this period in SE-positive eggs is threefold, which they consider to be well within statistically significant parameters.
Cutler: I'm very familiar with that study, and, unfortunately, it has been misinterpreted and misquoted. That part of the study really only represents a small number of the flocks that were even looked at, and it is based on the period Dr. Cheever mentioned of zero to five weeks postmolt. As I indicated earlier, this is the period during which virtually no eggs are laid. The study says that when a flock is infected with SE, the rate of contaminated eggs is approximately one to three per 20,000 eggs, and that's only in an infected flock. As far as the studies done by Dr. Peter Holt, I have a quote from Dr. Holta that says: "I do not support the claims that molting contributes to increased human illness because I am not aware of any epidemiological studies done in the field which substantiates such assertion. I certainly do not feel it is appropriate to extrapolate experimental data such as mine, which was performed under controlled conditions, into a real-world commercial situation."
Cheever: I certainly understand the difference between lab results as opposed to field results, but the Pennsylvania study was a field result. To correct Dr. Cutler, [the investigators were] talking about 20 weeks premolt to 20 weeks postmolt.
Cutler: I think Dr. Cheever has made an error. One of the things that the Pennsylvania study says is that 20 to 16 weeks premolt, there was higher SE shed than after the molt.

JAVMA: The background submitted with Resolution 3 states that the USDA has confirmed that forced molting is a severe stress that increases consumer health risk and that human Salmonella infections from eggs would be reduced by 2.1 percent if forced molting were eliminated. What is the source of those data?
Cheever: I can certainly get back to you on that. [Subsequent to the interview, Dr. Cheever provided a copy of the July 21, 1998 meeting summary of the USDA Farm Animal Well-Being Task Group. During this meeting a draft recommendation was discussed from the USDA-FSIS stating that the FSIS' SE risk assessment model predicts that eliminating the practice of induced molting would result in a mean reduction of 2.1 percent of human illness, and recommending several actions by the task group.]b
Cutler: [Responding postinterview:] This is not a valid document — it has "draft" stamped all over it. I'm familiar with the FSIS risk assessment, and its assumptions are precarious. The 2.1 percent differential is probably smaller than our year-to-year statistical variation might normally be. The important point is: as an industry we've reduced the incidence of Salmonella enteritidis in humans by more than 50 percent through quality assurance and vigorous testing programs, and there has been no change in molting practices in that time.

JAVMA: Do you think induced molting constitutes primarily an animal welfare issue or one of public misperception about a farm animal practice?
Cutler: I think really it is a misperception about what's going on on a farm. I believe that molt is a pro-welfare activity. It extends the life of a chicken, it gives the bird a period of rest, and it enables the bird to come back into production with better quality eggs. We know that if we didn't molt, we would have to use 47 percent more chickens, hatch 47 percent more chicks, have 47 percent more hatchery space, and kill 47 percent more male chicks.
Cheever: Of course it's an animal welfare issue. Any starvation is. We have an obligation to provide proper care, even if the economics do not support it. It has nothing to do with public misperception. The public knows more and more about forced molting. AVAR and United Poultry Concerns have brought it to the public's attention. In terms of killing 47 percent more [male chicks], AVAR does not wish to be jockeyed into having to respond to the industry by saying okay, let's select this evil over that evil.

JAVMA: What's the mortality rate in molted compared with unmolted flocks?
Cheever: We were unable to come up with data from unmolted flocks, the reason for that being quite simply that molted flocks represent 75 to 80 percent of the egg-laying flocks in the industry, and 100 percent of the responses we got to our questionnaire came from producers who practice forced molting. What we do know is that the mortality rate climbs up to 1.5 percent higher in a flock once it is molted. From a welfare standpoint we should not be using a mortality rate like an endpoint, like an LD50. What we strive to promote are humane agricultural practices, not what is merely survivable.
Cutler: There is no change in mortality numbers, but the pattern changes slightly. The mortality during a molt is really not much higher than the expected rate of mortality without a molt. Some of the birds that might have died in the subsequent period die during the molt instead. At the end, the mortality is identical between molted and nonmolted flocks. There are flocks in the United States, somewhere around 20 or 15 percent, that, for whatever reason, do not get molted. My data come from Don Bell,c probably the world's expert in molting chickens.
Cheever: The studies we read and the poultry experts from whom we seek information say the opposite, that forced molting does increase the mortality rate. [After the molt] many of them choke because of their frantic desire to get food back into their system. There is crop impaction, and again, with all of the damage that we find to both liver and bone structures as well as the gut, increased mortality is common sense.

JAVMA: Birds and mammals are physiologically different. How does species come into play in this production practice?
Cutler: Birds develop fat in the liver and a large fat pad in the abdomen while they're in production. The molt reduces this fat from the fat pad, and it removes the fat from the liver. Numerous follicles, including the yolk, are in the ovary and are resorbed and used as a source of nutrients during the molt. That represents 10 percent of the bird's weight. The reproductive tract is also resorbed. The combined weight of these beneficial losses is equal to the weight loss we observe in a controlled molt. Mammals have no such sources.
Cheever: Obviously there is a difference between mammalian and avian species, although I certainly do feel that their capacity to experience pain and suffering needs to be accounted for in both types of species. In no other agricultural species, whether mammalian or avian, would we tolerate such a steep drop of 20 to 25 and even 35 percent. That's a statistic from Don Bell, the so-called architect of forced molting.
Cutler: Dr. Cheever exaggerates on the length of molt. Nobody would go to 35 percent body weight. We know that's not good science. There are good articles and publications by Don Bell that say that's not a way you should do it. We monitor the birds very carefully, their health is watched, their general well-being is examined, and birds are molted in a safe and humane way.

JAVMA: What alternative does AVAR favor to induced molting?
Cheever: The most humane alternative, in AVAR's opinion, is to do what the egg industry does in Canada, where forced molting does not occur, or in Great Britain, where it was eliminated in '87, or in the European Union, where it was eliminated in '88. At the end of the first laying cycle, the [hens] would be sent to slaughter. Some [producers] might keep them for a second season, where they would have smaller egg numbers but increased egg size, giving them a slight profit margin. Down the line, some research design may be developed in which we can get the same synchronized molting without starvation or the use of a diet that's so imbalanced with some nutrients that it would still cause suffering.
Cutler: To date we have not found any molt methods that are equal to or any better than our current methods. Ongoing research is widespread. We have tests going on in Texas, here in California, and several other states [involving] different types of diet and management practices. Dr. Cheever refers to a second season of lay. When people do use a second season of lay, they have molted those birds. As far as certain areas prohibiting the molting of birds, what we as an industry have usually seen is either the ban is rescinded, as is happening in Sweden right now, or by and large, areas that restrict management practices lose the industry to an area where the industry is not restricted, then eggs are imported back into areas that have restrictions.
Cheever: Our discussions with the European Union indicate [the alternative practice] has not been a problem and that the situation seems to be working perfectly successfully. Dr. Cutler misunderstood me. I did not infer that the second egg-laying season was after a forced molt, but rather, after permitting a simple molt by the natural method for those very few flocks that do so.

JAVMA: If the HOD were to approve this resolution, where would AVAR and AAAP go from here?
Cutler: As I indicated, the AAAP supports the current AVMA policy on molting. We'll strive to see that that policy is kept in place. AAAP has discussed this area thoroughly at the recent production practices symposium we held. There was general agreement that molting is a necessary process.
Cheever: If the House of Delegates were to accept our resolution, we would be delighted and use AVMA's new position statement, with the unambiguous wording on complete prohibition of feed restriction, to strengthen our lobbying initiatives to take it before state legislatures and outlaw the practice in this country.


aDr. Holt is with the USDA Agricultural Research Service. This reference was in a 1999 letter to the United Egg Producers.
bThe draft 1998 FSIS recommendations have not been approved.
cUniversity of California-Riverside
Interview by Susan C. Kahler and Dr. Gail C. Golab, AVMA staff consultant to the Animal Welfare Committee