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Interactions Between Health and Production in Dairy Cattle

By

R. Page Dinsmore

, DVM, College of Veterinary Medicine and Biomedical Sciences, Colorado State University

Last full review/revision Feb 2021 | Content last modified Feb 2021

An important factor that influences dairy herd productivity is the type and incidence of disease in the herd. The basis of disease control programs includes knowledge of the frequency and biologic effect of disease, and information on the effectiveness of control procedures.

Most studies only report incidence rates of common, easily diagnosed clinical diseases such as mastitis, lameness, milk fever, retained placenta, or displaced abomasum. The frequency of subclinical disease is much more difficult to discern. The cost to obtain subclinical disease information is inflated by the need to use screening tests (eg, culture or somatic cell counts [SCC] for mastitis Mastitis in Cattle With few exceptions, mastitis occurs when microbes enter the teat via the teat canal. Almost any microbe can opportunistically invade the teat canal and cause mastitis. However, most infections... read more Mastitis in Cattle , fecal culture or ELISA for paratuberculosis Paratuberculosis in Ruminants Paratuberculosis, caused by Mycobacterium avium paratuberculosis , is a chronic, contagious granulomatous enteritis characterized in cattle and other ruminants by progressive weight loss, debilitation... read more Paratuberculosis in Ruminants ) for diagnosis. However, the high cost of subclinical diseases such as mastitis or paratuberculosis may justify the considerable expense of a control program, and veterinarians can play a vital role in designing these programs. There is zero tolerance for some diseases that have serious consequences for public health. The diagnosis of even one case of bovine spongiform encephalopathy Overview of Bovine Spongiform Encephalopathy Bovine spongiform encephalopathy (BSE) is a progressive, fatal, infectious, neurologic disease of cattle that resembles scrapie of sheep and goats (see Scrapie). It was first diagnosed in the... read more , brucellosis Brucellosis in Cattle The disease in cattle, water buffalo, and bison is caused almost exclusively by Brucella abortus; however, B suis occasionally is isolated from seropositive cows but does not appear to cause... read more , rabies Rabies Rabies is an acute, progressive encephalomyelitis caused by lyssaviruses. It occurs worldwide in mammals, with dogs, bats, and wild carnivores the principle reservoirs. Typical signs include... read more , or tuberculosis Tuberculosis in Cattle Most of the general discussion above applies to bovine TB. The introduction of milk pasteurization was a major step in the fight against Mycobacterium bovis TB and continues to be an important... read more in areas thought to be free of those conditions is cause for immediate action.

Influence of Disease on Productivity

Increased culling, reduced milk or protein yield, increased adult cow mortality, and reduced reproductive efficiency are all potential results of disease in adult cows. Milk production is often profoundly reduced in cows with clinical disease. The duration of acute clinical disease is often short, but the effects of the disease may persist throughout the entire lactation. Early lactation is the highest risk period for many diseases. Disease during early lactation may reduce peak milk yields and therefore contribute to lower total lactational yields. Through advances in animal husbandry and health management programs, in concert with close involvement of veterinarians, many farms have minimized clinical syndromes associated with infectious and metabolic disease. The trend toward larger units and shrinking profit margins has encouraged a shift toward optimizing herd or group productivity through reduction of subclinical diseases such as ketosis Ketosis in Cattle Ketosis is an elevated concentration of ketone bodies (acetone, acetoacetate, beta-hydroxybutyrate) in all body fluids. Key clinical signs of ketosis are vague but include anorexia, decreased... read more Ketosis in Cattle , mastitis Mastitis in Cattle With few exceptions, mastitis occurs when microbes enter the teat via the teat canal. Almost any microbe can opportunistically invade the teat canal and cause mastitis. However, most infections... read more Mastitis in Cattle , acidosis Subacute Ruminal Acidosis Ruminant animals are adapted to digest and metabolize predominantly forage diets; however, growth rates and milk production are increased substantially when ruminants consume high-grain diets... read more , and laminitis Laminitis in Cattle Equine and bovine laminitis are distinctly different. Although acute laminitis occurs in both species and can be caused by grain overload, other etiologies can affect the equine laminae. A major... read more , which can have a major impact on productivity.

Infectious disease still represents a major source of loss to dairy industries worldwide. In Britain, outbreaks of foot and mouth disease Foot-and-Mouth Disease in Animals Foot-and-mouth disease is one of the world's most economically important viral diseases of livestock. The virus infects cattle, pigs, and sheep and many cloven-hoofed wildlife species. The infection... read more Foot-and-Mouth Disease in Animals (as well as bovine spongiform encephalopathy Overview of Bovine Spongiform Encephalopathy Bovine spongiform encephalopathy (BSE) is a progressive, fatal, infectious, neurologic disease of cattle that resembles scrapie of sheep and goats (see Scrapie). It was first diagnosed in the... read more ) are dramatic examples of the disastrous effects of infectious diseases on productivity. Other serious infectious diseases such as tuberculosis Tuberculosis in Cattle Most of the general discussion above applies to bovine TB. The introduction of milk pasteurization was a major step in the fight against Mycobacterium bovis TB and continues to be an important... read more , brucellosis Brucellosis in Cattle The disease in cattle, water buffalo, and bison is caused almost exclusively by Brucella abortus; however, B suis occasionally is isolated from seropositive cows but does not appear to cause... read more , bluetongue Overview of Bluetongue Bluetongue is an infectious arthropod-borne viral disease primarily of domestic and wild ruminants. Infection with bluetongue virus (BTV) is common in a broad band across the world, which until... read more , and vesicular stomatitis Vesicular Stomatitis in Large Animals Vesicular stomatitis (VS) is a viral disease of livestock transmitted primarily by biting flies and midges. The disease results in characteristic vesicular lesions that can occur on the muzzle... read more continue to affect livestock around the world. In North America, more common infectious diseases that must be actively controlled include the contagious mastitis pathogens Mycoplasma bovis, Staphylococcus aureus, and Streptococcus agalactiae; bovine viral diarrhea Bovine Viral Diarrhea and Mucosal Disease Complex Bovine viral diarrhea/mucosal disease is a pestivirus infection of cattle and other ruminants. Infection leads to immunosuppression and can cause signs in multiple body systems in addition to... read more ; salmonellosis Salmonellosisin Animals Salmonellosis is infection with Salmonella spp bacteria. It affects most animal species as well as humans and is a major public health concern. The clinical presentation can range from a healthy... read more Salmonellosisin Animals ; paratuberculosis Paratuberculosis in Ruminants Paratuberculosis, caused by Mycobacterium avium paratuberculosis , is a chronic, contagious granulomatous enteritis characterized in cattle and other ruminants by progressive weight loss, debilitation... read more Paratuberculosis in Ruminants ; and pneumonia Bacterial Pneumonia in Cattle Mannheimia haemolytica serotype 1 is the bacterium most frequently isolated from the lungs of cattle with BRD. Although less frequently cultured, Pasteurella multocida is also an important cause... read more . Excellent control programs have been developed for most of these diseases, but their adoption is quite variable.

The effects of disease on productivity can be direct (such as mastitis causing a profound reduction in milk yield) or indirect (lameness leading to reduced feed intake, thus causing reduced milk yield). Diseases occurring in early lactation can also cause cascading effects that ultimately reduce productivity over the entire lactation. For example, periparturient disorders often are seen as a complex, and cows diagnosed with parturient paresis are at increased risk of retained placenta, complicated ketosis, and mastitis. Cows with dystocia and retained placenta are at increased risk of metritis. Subclinical ketosis Ketosis in Cattle Ketosis is an elevated concentration of ketone bodies (acetone, acetoacetate, beta-hydroxybutyrate) in all body fluids. Key clinical signs of ketosis are vague but include anorexia, decreased... read more Ketosis in Cattle leads to increased risk of displaced abomasum and reduced milk production. The best documented direct effect is the effect of mastitis on milk yield. A single case of clinical mastitis can result in a milk yield loss of 300–400 kg/lactation, with variations ranging from negligible to 1,050 kg. Mastitis Mastitis in Cattle With few exceptions, mastitis occurs when microbes enter the teat via the teat canal. Almost any microbe can opportunistically invade the teat canal and cause mastitis. However, most infections... read more Mastitis in Cattle during early lactation is associated with higher losses (450–550 kg) than cases seen later in lactation.

Losses resulting from subclinical disease are often considerable. The best-described relationship between subclinical disease and productivity is the effect of subclinical mastitis on milk yield. Each 2-fold increase in SCC >50,000 cells/mL caused a loss of 0.4 kg milk/day in primiparous cows and 0.6 kg milk/day in multiparous cows. Total lactational milk yields were estimated to be reduced by 80 kg for primiparous cows and 120 kg for multiparous cows for each 2-fold increase in the geometric mean SCC >50,000 cells/mL. Other subclinical diseases (eg, paratuberculosis) have also been related to reduced productivity.

Diseases that delay or inhibit conception have a negative effect on herd productivity by prolonging the time cows spend in lower-producing stages of lactation, by reducing the number of offspring for replacements or for sale, and by increasing the likelihood the animal will be culled prematurely. Several diseases have been associated with decreased conception rates. The likelihood of conception was reduced by 14%, 15%, and 21% for cows that experienced retained placenta, metritis, or ovarian cysts, respectively. Mastitis, metritis, and ovarian cysts reduced the likelihood of cattle being bred for the first time. Postpartum diseases that prolong negative energy balance in early lactation also have a negative effect on reproductive performance through alterations in hormonal levels.

The effect of disease on longevity has been investigated. A large proportion of cow culling is considered involuntary (driven by disease, injury, or death) rather than for reasons of low production. The premature removal of a cow from the herd reduces lifetime milk yield. Reproductive failure and mastitis are consistently recorded as the top two reasons for culling.

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