High Immune Responders:

Animals with a higher immune response tend to be more able to combat any pathogen that they will be exposed to throughout their lifetime. For instance, mastitis is observed to occur less in cattle that have an enhanced immune system which can be identified using a technology called High Immune Response (HIR) technology (Thompson-Crispi et al. 2014).  HIR technology tests the ability of an animal to mount an immune response against a pathogen and it is found that sires who respond better to the test produce daughters who have lower rates of many diseases as well as producing better colostrum (Thompson-Crispi et al. 2014).  The inheritance rate of high immune responders appears to be significantly higher than that of mastitis resistance on its own with an inheritance coefficient of 0.25-0.35 (Thompson-Crispi et al. 2014). While this inheritance coefficient is still relatively low, breeding for HIR in cows may be more rewarding than breeding for resistance to certain diseases, which their inheritance coefficient usually even lower.

Mastitis:

When we talked to producers along with other members associated with the dairy industry it was mentioned that mastitis was one big challenge in the industry in terms of animals welfare. Because of this mastitis is one disease that is of top concern for our study. Mastitis is a fairly common bacterial infection in the udder which causes a persistent, inflammatory reaction in the tissue of the udder. This swelling can be very painful and uncomfortable for the dairy cows, and this negatively affects their welfare. Mastitis is contagious and can be spread through contact with an infected milking machine, or other infected materials. This infection is typically treated using antibiotics. Milk from an infected cow or a cow undergoing treatment with antibiotics cannot be used for human consumption and must be thrown out. Mastitis is a costly disease in the dairy industry due to reduced milk production, discarded milk, early culling, veterinary services, and labor costs (Thompson-Crispi et al. 2014). When observing the cows across lactations a positive genetic correlation can be seen, from this information heritability can be inferred (Heringstad et al. 2005). Mastitis has a heritability coefficient of 0.07 showing that through selective breeding we can reduce the rate of mastitis (Koeck et al. 2012).

Metritis:

Metritis refers to a reproductive disorder that is characterized by a bacterial uterine infection which can cause swelling of the uterine wall and vaginal discharge, and is typically treated using antibiotics (Haimerl and Heuwieser, 2014). In postpartum cows metritis is associated with other reproductive risks such as stillbirths. This disease while not as prevalent in the industry as mastitis or digital dermatitis can still have a negative impact on the welfare of dairy cows and is fairly common in fresh cows. Metritis has been found to have a genetic component and has been found to have a heritability coefficient of 0.06 (Giuliodori et al. 2013).

Ketosis:

Ketosis is a metabolic disorder that is associated with higher risk of other welfare concerns such as displaced abomasum, lameness, and Metritis (Ehret 2015). Ketosis is what happens when the body gets its energy from the ketone bodies in the blood, instead of going through glycolysis. Ketosis can happen either 1-2 weeks after calving, or near peak lactation. This metabolic disorder while not on of the biggest concerns for this study is still fairly common, a study in Europe found that the herd average for ketosis was 43% in Germany, 53% in France, 31% in Italy, 46% in the Netherlands, and 31% in the United Kingdom (Berge and Vertenten, 2014). This metabolic disorder can be prevented through modifying the cows diet or can be treated by 300 mL of 100% propylene glycol orally once daily for 5 days (Gordon et al. 2013). Prediction of this disease is most effective when metabolic and milk performance is recorded but genetics can be used as well (Ehret 2015). Ketosis was found to have a heritability coefficient of 0.11 (Heringstad et al. 2005).  A field study to determine the prevalence, dairy herd management systems, and fresh cow clinical conditions associated with ketosis in western European dairy herds (Berge and Vertenten 2014 )

Johne’s:

Johne’s disease is contracted by fecal contamination and results on untreatable diarrhea that can be deadly making it a serious welfare concern in cattle (Wolf et al. 2014).  It has a long incubation period making it difficult to detect and results in economic losses in terms of decreased milk production (Wolf et al. 2014).  This is also a disease of concerns it is suspected that the causal bacteria, Mycobacterium avium ssp. Paratuberculosis, is related to crohn's disease in humans; should this be proven true there would be greater demand for cattle free of this bacteria due to the possible threat to human health (Wolf et al. 2014).  A proposed method for eliminating this disease is selecting only sires with a low rate of the disease and that test negative in ELISA test; it is proposed that the disease could be eliminated in 147-223 years (van Hulzen et al. 2014).



Digital Dermatitis:

From talking with producers and other people involved in the dairy industry we found that lameness is one challenge that the industry has when it comes to the cows welfare. For this study we will focus on lameness that is caused by a bacterial infection called Digital Dermatitis. This infection causes lesions on the heel of the foot, which may extend to between the claws of the foot and to the front of the foot. This disease can be very detrimental to a herd as it is highly contagious. The bacteria that usually causes Digital Dermatitis is in the genus Treponema and the Spirochete family. The infection usually causes mild to moderate lameness, and swelling usually does not occur unless a secondary infection is present. An outbreak of Digital Dermatitis usually occurs in conditions with high humidity and poor hygiene, but can also be transferred when hoof trimmers are not sterilized between cows. An effective treatment of digital dermatitis is a tetracycline hydrochloride paste applied to the infected area (Higginson et al. 2013). It has also been found the the lesions can be painful during the healing and active stages so some type pain management may be necessary (Higginson et al. 2013). The heritability coefficient for infectious lesions in dairy cattle has been found to be 0.092, this includes lesions caused by digital and interdigital dermatitis, foot rot, and heel erosion (Chapinal et al. 2013)

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