11 December 2012

11 minute read

Items of Note

The majority of operations that specialize in raising dairy heifers have been in business for less than 10 years; less than 10 percent have been in business for 21 or more years. The number of clients (dairies or individuals) these operations raise heifers for varies. Generally, the larger the heifer-raising operation the more clients it serves. When heifers from multiple clients are allowed contact with one another on these operations, the potential for disease transmission increases.

Most heifers sent to heifer-raising operations are returned to their dairy of origin; however, about 20 per cent of heifers are not returned and are sold through auction markets, dealers, or directly to another dairy.

Similar to all livestock enterprises, heifer-raising operations face an array of challenges. The majority of producers that raise heifers reported that heifer health, client relations, payments from producers, and feed cost/availability were very important challenges. The availability of labor was not a very important challenge to the majority of producers.

Heifer calves are sent to heifer-raising operations at various ages. Some dairies send calves within a day or so after birth; some send them after weaning; and others send pregnant heifers. The majority of heifer-raising operations received weaned calves and sent them back as pregnant heifers. In addition to dairy heifers, some heiferraising operations housed dairy bulls, dairy steers (primarily Holstein), and beef cows. Approximately one-third of operations had dairy bulls intended for breeding during 2010, while less than one-fifth had other types of cattle.

Animal ID

Individual animal identification (ID) is important to heifer-raising operations for multiple reasons, including general inventory practices, production and treatment information, and, in the case of retained ownership, ensuring that the heifers are returned to the dairy of origin.

In addition, applying and maintaining individual animal ID is important in disease-outbreak situations in which determining the source and movement of affected or exposed cattle is vital.

Almost all operations had some form of individual animal ID, and the majority used nonelectronic ear tags inserted prior to arrival at the operation. Electronic or radio frequency ID (RFID) ear tags were used on about onethird of operations.

Branding is one method of permanent herd identifi cation and in some instances, when numbers instead of characters are used, can be used as individual animal ID. About 20 per cent of operations raised heifers that were branded.

Record Keeping

Keeping high-quality, usable records is important to any livestock operation. Keeping records is even more important to heifer-raising operations that house cattle from multiple sources, because heifers on these operations are often managed together and information such as breedings and treatments is reported to the dairies of origin and/or buyers.

Records that include information on the use of antibiotics in individual animals are essential to ensure that heifers treated at the heifer-raising operation are not marketed by the dairy of origin or the seller before the proper milk or slaughter withdrawal period.

About 70 per cent of operations recorded individual treatments administered to sick dairy heifers and kept written or computerized records of dairy-heifer growth and/or health information.

Housing and Welfare

Housing systems for preweaned heifers have traditionally focused on individual hutches or pens, which minimize direct contact among calves. Current research suggests that housing preweaned heifers as a group reduces labor costs associated with feeding because grouping the animals allows for the use of automatic or free-choice feeding systems.

When housed in groups, preweaned calves are socialized earlier in life, experience group learning, and their growth is equivalent to calves in individual-housing systems. Weaned and pregnant heifers have traditionally been housed in groups of similar age, rather than individually.

The majority of heifer-raising operations housed preweaned heifers in an outside hutch/pen or individual inside pen in a cold calf barn. Housing for weaned heifers included pasture, freestall, dry lot/multiple-animal area, bedded pack/open shed, and multiple-animal inside area/barn/shed.

Pregnant heifers were housed in facilities similar to that of weaned heifers, but more operations used freestalls for pregnant heifers.

Vaccination

Vaccination remains a key component of disease control and prevention on most livestock operations. About 40 per cent of heifer-raising operations raised heifers that were vaccinated against brucellosis, even though vaccinating dairy heifers against brucellosis is no longer mandatory in many States.

All 50 States were considered free from brucellosis as of February 2012. More than 8 of 10 operations vaccinated cattle against any disease during 2010, and more than three of four operations vaccinated against bovine viral diarrhea (BVD), infectious bovine rhinotracheitis (IBR), or parainfl uenza type 3 (PI3). Vaccines for these three diseases are commonly administered together in a single dose.

Disease and Testing

Testing individual heifers for transmissible diseases such as BVD and brucellosis before or when they arrive at a heifer-raising operation is recommended. If heifers test positive, then mitigation steps can be taken to reduce the risk of disease transmission to the rest of the herd.

Since the majority of operations raised heifers owned by the dairies of origin, testing also provided an indication of the status of the source herd. Depending on which States heifers travel to, regulations might require testing for brucellosis and/or tuberculosis (TB).

Heifers shipped out of the United States are required to undergo some disease testing performed prior to shipment. Half of operations tested heifers for at least one disease during 2010; BVD and TB tests were the two most common tests performed.

Cattle movement on and off heifer-raising operations is generally dependent on the age of the heifers. Operations with preweaned heifers might receive new heifers on a daily basis, while those that raise weaned heifers might receive heifers every 2 to 4 weeks. Heifer-raising operations received an average of 43.2 shipments during 2010, and the average shipment size was 9.9 heifers.

The average number of shipments leaving heifer-raising operations was 19.4, and the average number of heifers per shipment was 24.9.

The number of shipments for both incoming and outgoing heifers was higher for large operations compared with small operations, and the number of heifers per shipment increased as herd size increased. More than one-fourth of incoming and outgoing shipments traveled 100 miles or more, and one-third of all shipments crossed State lines.

Overall, 12.2 per cent of operations sent heifers to another country, with Turkey, Mexico, and Russia being the top three destinations for heifers sent out of the United States.

Colostrum

Administering colostrum to newborn calves is necessary for the absorption of immunoglobulins. Calves should receive colostrum within 2 to 3 hours of birth to increase the potential for passive transfer of immunity.

Since heifers are not routinely moved to heifer-raising operations within 2 to 3 hours, colostrum should be fed at the dairy of origin, before shipment to the heifer-raising operation. All operations that raised preweaned heifers reported that colostrum was administered at the dairy of origin.

Milk Replacer

Milk replacer was fed on the majority of heifer-raising operations (85.9 per cent), with one-third of operations feeding nonmedicated replacer and two-thirds feeding medicated replacer.

Under regulations imposed in 2009, medications used to control or treat diarrhea can only be fed for 14 days in milk replacer. Although producers could continue to feed medications to improve weight gain and feed efficiency, the lower dose of medication might not be cost effective.

The most commonly fed medication in milk replacer was oxytetracycline in combination with neomycin (NT). Prior to new regulations in 2009, NT was two parts neomycin and one part tetracycline.

The 2009 regulations now require the two medications be mixed in a ratio of 1:1. Decoquinate and lasalocid were each fed by one of five operations (19.7 and 19.6 per cent, respectively).

Nonsaleable or waste milk was fed on one-third of operations. Waste milk was fed on a higher percentage of operations in the West region than in the East region (78.6 and 21.9 percent, respectively). The majority of heifers were fed 2 to 3 quarts twice daily, resulting in a total volume of 4 to 5 quarts per day. The average age at weaning was 7.1 weeks.

Antibiotics in Heifer Feed

The use of antibiotics in livestock feed is under scrutiny due to concerns about antibioticresistant strains of bacteria that could impact human health.

There are three general types of medications used in feed for heifers: ionophores, coccidiostats, and antibiotics.

Ionophores alter the rumen bacterial population, change the production of certain volatile fatty acids, act as growth promotants, and prevent coccidiosis.

Although ionophores are antibiotics, they are not used in human medicine and are not under scrutiny. Common ionophores are lasalocid (Bovatec®) and monensin (Rumensin®). Coccidoistats, such as Deccox® (decoquinate), are also used to prevent coccidiosis.

Antibiotics, such as chlortetracycline and neomycin, are labeled for the prevention or treatment of respiratory disease or scours.

Some antibiotics are also labeled for increasing rate of gain and improving feed efficiency. More than three-fourths of operations fed some antibiotics to heifers, and more than 8 of 10 weaned and pregnant heifers were fed ionophores in feed during 2010.

Heifer Origins

Ideally, heifer-raising operations would either raise heifers from a single source or not allow contact or commingling among heifers from different dairies. Commingling or allowing contact among heifers from different dairies can result in the transmission of many important dairy cattle diseases, including TB, brucellosis, salmonellosis, BVD, and hairy heel warts.

In addition, disease can be transmitted if heifers have contact and/ or commingle with adult dairy cattle, beef cattle, or feeder cattle. Of particular concern is the risk of transmitting TB when any breeding stock, particularly dairy heifers, are commingled with cattle of Mexican origin.

No operations in the study reported housing cattle of Mexican origin. Dairy heifers were commingled with heifers from other operations on 60.3 per cent of operations.

On 20.9 per cent of operations, heifers were housed separately but allowed nose-to-nose contact with heifers from other dairies. The majority of heifer-raising operations also had dogs or cats on the operation. Between 20 and 30 per cent of operations had beef cattle, chickens or other poultry, or horses, donkeys, or mules.

Wild Animals and Disease

Wild animals may carry diseases that can be transmitted to cattle. For example, deer and coyotes in parts of Michigan can be reservoirs for TB. BVD virus can also infect deer and potentially be transmitted to cattle. Elk and feral swine can be infected with brucellosis and potentially transmit the disease to cattle.

Raccoons, although primarily recognized as potential sources of rabies, can also carry Salmonella and other pathogens. Foxes can harbor leptospirosis and Neospora, which are recognized cattle diseases. Coyotes, foxes, or raccoons were observed on 9 of 10 heifer-raising operations during 2010. Deer or signs of deer were observed on about 4 of 10 operations in the West region and on about 9 of 10 operations in the East region. In heifer-calf housing areas, deer were observed at least monthly on 21.1 per cent of operations, less than monthly on 24.1 per cent, and never observed on 54.8 per cent of operations.

Farm Visitors

Vehicles used to transport heifers—especially preweaned heifers—should be washed and rinsed out between every shipment. Transport vehicles used to haul cattle from multiple operations in multiple shipments without being cleaned could pose a disease risk (e.g., Salmonella) to heifers. Transport vehicles were washed or rinsed out after every shipment on 26.1 per cent of operations, and a disinfectant was used to wash out vehicles on 24.4 percent of operations.

Consultants are very important to the success of heifer-raising operations, but they can also be a source of disease introduction or spread. For example, consultants who do not disinfect footwear after visiting an operation could spread disease to the next operation visited. Veterinarians were used weekly or monthly by more than three-fourths of operations. More than 6 of 10 operations (63.9 per cent) used a nutritionist weekly or monthly, and almost half of operations used an artifi cial insemination (AI) technician during 2010.

Federal or State animal health offi cials or university/extension personnel were consulted by 20 to 25 percent of operations. About 9 of 10 operations had veterinarians and AI technicians use a footbath, disposable boots, or clean coverall/boots as a biosecurity practice.

Breeding practices can result in disease transmission between animals. Bovine leukemia virus (BLV) can be transmitted during breeding or pregnancy exams via blood on palpation sleeves. Natural breeding can also result in transmission of trichomoniasis or other diseases. Dairy heifers were bred on 75.3 percent of operations. Of these operations, 18.5 per cent used only natural breeding (bulls), 31.5 per cent used only AI, and 50.0 per cent used a combination of natural breeding and AI. Bull management practices related to health, such as breeding soundness exams and disease testing, were performed by about 15 to 37 per cent of operations that used breeding bulls.

Digestive problems and pneumonia were the most common diseases or disorders affecting preweaned heifers, and 18.2 and 16.4 per cent of preweaned heifers, respectively, were treated with antibiotics during 2010 for these two disorders.

Antibiotics were used to treat diarrhea in preweaned heifers on 85.7 per cent of operations. Respiratory disease was the most common disorder affecting weaned heifers (11.2 percent of heifers).

Antibiotics were used on 82.1 per cent of operations to treat respiratory disease in weaned heifers. Pregnant heifers were infrequently affected or treated for disease. As expected, respiratory and digestive diseases were the primary causes of death for heifers. Half of operations performed any necropsies to determine the cause of death in heifers. Rendering, burying, and composting were the most common methods to dispose of dead heifers.

November 2012