Although my herd has been unaffected by this disease, it has been a widespread problem for the industry. I wrote a paper on the subject covering how AM has affected producers and some of the progress and frustration that has come of AM. Doc, Vet might be in the cards for me yet.
Arthrogryposis Multiplex is a genetic defect that has only affected three calf crops but has put the entire beef industry and the American Angus Association on guard and has caused substantial financial damage to farmers and ranchers across the nation. Arthrogryposis Multiplex, also known as AM, is a genetic defect that causes calves to be born with a twisted spine and limbs (Kaiser, 26). The calves lack adequate muscling and are born underdeveloped (Kaiser, 38). How did an obviously negative defect come about? When line breeding certain families of cattle, the object is to improve the good traits of the herd, but it also brings out the genetic impurities of AM. When a certain line in the Angus breed was line bred over several years, the genetic defect of AM surfaced.
What exactly is AM? What are the effects on the calf? AM is the name scientists decided to give to a genetic defect that exhibits several characteristics such as Arthrogryposis, Kyphoscoliosis, and Muscle Hypoplasia (Kaiser, 38). The defect is lethal and causes the calf to either be born dead or causes it to die shortly after birth (Kaiser, 38). Arthrogryposis (also known as arthrogryposis multiplex congenita) is the condition in which multiple joint contractures form, as evidenced by the twisted and stiff limbs of an affected calf (Kaiser, 38). Muscle weakness is also a sign of calves affected with Arthrogryposis. Kyphoscoliosis is a condition where the spine is curved and there are also problems with muscle control. Muscle Hypoplasia is the condition where the tissues and organs of the calf are underdeveloped. In addition to Kyphoscolosis, calves with AM have torticollis and associated abnormalities of the ribs and sternum (Kaiser, 38). There may also be a cleft palate, cranial doming, and lateral deviation of the facial bones. (Kaiser, 38). The ear pinnae are often set lower than normal and closer together on the back of the skull (Kaiser, 38). All these conditions are symptoms that an affected calf will exhibit. So with all those symptoms, why is this defect only called AM? AM is also, and perhaps more commonly known as, Curly Calf Syndrome, or CCS. This obviously refers to the "curly" appearance of the calf. Another name for AM is Bovine Arthrogryposis Multiplex Congenita, or BHAMC. Some other names that have been used to name this disease have been Muscle Hypoplasia, Arthrogryposis, and Kyphoscoliosis (MAK) (Kaiser, 38).
AM came about as a result of line breeding the popular line of GAR Precision 1680 line of cattle in order to maximize their carcass traits and bring the cattleman more value on the USDA yield and quality grading system. The line certainly excelled, but soon stacked carcass genetics led to a cattleman's worst nightmare -- dead calves (Pullman, 104). Now cattleman were losing money right when a dead calf was born rather than getting extra dollars when they sold their calves at weaning or as finished cattle out of the feedlot. When research began on AM to seek out its origin, the line of GAR Precision 1680 was on one or both sides of the pedigrees of the all of the affected calves (Kaiser, 26). Upon further research, his maternal grandsire, Rito 9J9 of B156 7T26 was also in certain calves' pedigrees that were affected and had 1680 on only one side of the pedigree (Kaiser, 38). Although cattlemen were adding value to their calves with increased carcass merit, it ended up costing the entire beef industry big time with more economic loss than several dead calves.
When cattlemen bred lines of cattle tracing to 1680 or 9J9, not every calf born was twisted and dead at birth. In fact, there were surprisingly few affected calves relative to the number of Angus cattle in the USA. Many cattlemen bred their cows via A.I. or natural service to AM carrier, or AMC, bulls without knowing it (Pullman, 105). However, their cows did not carry the AM gene and so fifty percent of the calves from that cross were carriers but not affected (Pullman, 105). The other fifty percent were completely free, or AMF (Pullman, 105). They can't produce AM affected calves, or AMA calves. However, when two carriers of the AM gene were mated, approximately twenty- five percent of their calf crop were born affected and were born twisted and dead or died shortly after birth (Pullman, 105). Twenty-five percent of the calves were AMC because AM is a recessive gene and needs at least two carriers to bring it out (Pullman, 105). Fifty percent of the calves are AMC and have a chance of producing AMA calves if they are bred to other AMC cattle (Pullman, 105). Although it may seem confusing, it comes down to the fact that years of stacking genetics brought several AMC cattle into breeding herds. Then, inevitably, two AMC cattle were mated and produced an AMA calf which was found in the spring of 2008 and caused a national scare.
You may be wondering, "Is there a solution to this defect? What's being done to stop it?" The good news is that Dr. David Steffen, DVM, Ph.D. and Dr. Jonathan Beever, Ph.D., DVM, were on the case as soon as the first AMA calves were reported (Pullman, 104). The American Angus Association asked their members to remain calm about the matter and were prompt as possible when delivering updates on the progress being made to pin down the defect. Dr. Beever asked all cases of AMA calves to be immediately reported directly to him so that research could be conducted. As fall Angus production sales began to be planned, people were understandably concerned about buying cattle. However, Dr. Beever's work on the problem allowed for a DNA test to be conducted on cattle at a breakneck speed that never could have been attained only a year ago (Pullman, 105). The American Angus Association authorized certain laboratories to conduct the tests and Dr. Beever has now identified 736 popular A.I. sires' AM condition (AMC or AMF) (Kaiser, 26). Although Dr. Beever from the University of Illinois was a driving force behind research and diagnosis of AM, Dr. David Steffen, DVM., Ph.D., from the University of Nebraska was also investigating AM and diagnosed it as a genetic rather than an environmental influenced defect (Pullman, 104).
Now we have a DNA test available for the detection of AM. This test is still being modified and the latest way to collect DNA from cattle is pulling hair from the tail switch. The cattle tested are those that trace back to 1680 or 9J9 on either side of the pedigree (Pullman, 106). These "suspect" cattle then have their DNA sample collected, labeled, and sent to an approved AM testing lab. Then the cattle producer can find out whether or not his bulls or cows he plans on breeding are AMF or AMC (Pullman, 106). So far as A.I. sires go, the majority of A.I. studs only offer semen on AMF bulls in order to greatly reduce the chances of getting AMA calves.
Producers that have AMC cows have generally agreed that culling the cows or selling them is the best way to try and make their entire herd AMF (Pullman, 105). Although progress has been made to the point where only for sure AMC cows can be culled, selling high dollar registered cows at sale barn market prices represents a fairly large loss to the producer (Pullman, 105). The quality of the meat of the animal is NOT affected by the defect, but AMC cattle are generally terminal. However, some producers have decided to keep some AMC flush and herd cows and to test their offspring from AMF bulls. (Pullman, 106). If AMC cattle need to be fed out and sold as beef, what about all the bulls in the breed that producers were selling and collecting semen on? Many reputable seedstock producers immediately tested their cattle and got rid of AMC bulls and cows they were preparing to sell as breeding stock (Pullman, 105). Selling these breeding stock animals as meat animals brings significantly less than quality
breeding stock unless carefully marketed. Therefore, many of the huge bull sales that take place each fall and spring either had to be canceled or have far fewer bulls than they originally had to offer. The potential income from these sales were slashed and many cattlemen are still feeling the ill timed affects of AM. Due to an unsteady economy, these producers needed their big sale's income more than ever, and that income was either cut or simply didn't come in at all. However, despite the frustration and problems AM has caused, it has been nipped in the bud and is well on its way to no longer being a problem in purebred Angus and Angus influenced herds (Pullman, 106).
As I stated, AM has been directly affecting the breeding portion of the Angus industry. However, it also affects the beef sector of the industry. The superior carcass genetics that the Angus breed and the 1680 line in particular are now lost, as few producers want to chance getting an AMA calf. Due to the immense popularity of 1680, breeding beef cattle numbers could be largely affected by the reduction of selection of sires and dams who are 1680 free (Pullman, 104). However, the testing of suspect cattle has caused some problems. Due to the early stages of testing, some high quality prospect sires have tested AMC and the producers took the respectable action to castrate the bulls and feed them out to be butchered for meat so that AMC genetics, not matter how good, would not be passed along. However, sometime the AMC cattle were later declared AMF and vice versa. However, viewing the entire picture of the Angus and beef industry in general, the frustrations caused are small compared to what may have resulted if no test had been instrumented (Pullman, 105).
Arthrogryposis Multiplex is a genetic defect that has only affected three calf crops but has put the entire beef industry and the American Angus Association on guard and has caused substantial financial damage to farmers and ranchers across the nation. AM, also known as CCS, has caused panic in all sectors of the beef industry, particularly with producers raising Angus and Angus influenced cattle (Pullman, 106). Many have become frustrated with how the defect has affected their operations and a substantial financial loss has been realized by the industry, particularly in the seedstock sector. Although testing suspected AMC cattle is still in the early stages, it has saved many producers from a lot of grief and brought further spread of the defect under control (Pullman, 105). On the other hand, lots of semen sales and bull production sales have been stopped and have caused financial hardships. Considering the give and take, the beef or more directly the Angus industry, considers the defect under control and people are beginning to regain confidence in the Angus breed.
Works Cited:
Kaiser/MD/DVM, Lana. "Arthrogryposis Multiplex." Bovine Veterinarian March & April
2009: 38-40.
Kaiser/MD/DVM, Lana. "Arthrogryposis Multiplex." The Michigan Cattleman Winter
2008: 26-27.
Pullman, Jaime. "Angus Angst." Working Ranch Spring 2009: 104-06.
Special thanks to Lana Kaiser for her consent of the use of her articles in this paper and her
support in helping me find on AM.
