Feeding dairy cows under various disease conditions
Several feeding management strategies can be used as a supportive treatment for various health problems. This article provides insight into the most common diseases and metabolic disorders in cattle. It also discusses feeding strategies that can be adopted to reduce the impact on animals, farm operations, and profitability.
Rumen acidosis
Low-fibre diets allow fermentation acids to accumulate in the rumen and cause ulcers in animals consuming too much grain with little fibre. The infective bacteria then enter the bloodstream via ulcers in the rumen and finally get into the liver where they cause abscesses.
These problems can be controlled by gradually adding grain to the diet. Feed additives may also help to reduce the risk of acidosis. Sodium bicarbonate, for example, can be included at 2% of the diet for the first 2 weeks when introducing grain.
Frequent feeding (for example, 4-5 times per day) may result in cows spreading their feeding time more evenly throughout the day. The steady input of nutrients into the rumen should improve rumen function and stabilise rumen pH, thereby reducing the risk of acidosis.
Ketosis
Ketosis is often observed in animals fed on silages undergoing aerobic deterioration or clostridia activities, and also with silages having large amounts of non-protein nitrogen formed during fermentation. The disease is characterised by decreased rumen motility, reduced feed intake, convulsions, rapid decline in body weight, and reduced milk production.
Poorly preserved silages should, therefore, be withdrawn from the feeding programme, or at least be fed in very restricted amounts. Some feed additives, including niacin, calcium propionate, sodium propionate, propylene glycol, and rumen-protected choline, may help prevent and manage ketosis. These supplements should be fed in the last 2-3 weeks of gestation, as well as during the period of ketosis susceptibility.
Fatty liver
Fatty liver is a disorder affecting highly productive dairy cows, resulting from an excessive negative energy balance at the onset of lactation. When large amounts of body fat reserves are mobilised in response to insufficient dietary energy supply, it results in a transfer of fatty acids to the liver. The condition is associated with symptoms such as anorexia, depression, shortness of breath, enlarged spleen, rapid weight loss, drop in milk production, weakness, nervous system problems, and death.
Rumen-protected choline and propylene glycol have proven effective at preventing fatty liver. Choline probably enhances hepatic secretion of very low-density lipoprotein, and propylene glycol most likely reduces fatty acid mobilisation from adipose tissue. Shortening or eliminating the dry period is a management strategy that reduces the magnitude of negative energy balance after calving and triglyceride accumulation in the liver.
Urinary calculi
The term ‘urinary calculi’ refers to mineral deposits in the urinary tract, which may block the flow of urine in the urethra, particularly in castrated male cattle. Prolonged blockage generally results in urinary bladder rupture or the urethra releasing urine into the surrounding tissues.
Some grains and forages appear to favour urinary calculi formation. These include grasses, wheat straw, sugar beet pulp, sorghum, and cottonseed meal. High-phosphorus, low-calcium diets may be a contributing factor, especially when high-concentrate diets are not adequately supplemented with calcium sources such as limestone. The deficiency of vitamin A may also increase the severity of urinary calculi.
Displaced abomasum
Displaced abomasum appeared to increase during the first 4-6 weeks after parturition and is characterised by sunken eyes, weakness, depression, dilation of abomasum with gas, reduced motility of all the cow’s stomachs, and marked drop in milk production.
To reduce the incidence of displaced abomasum, feeding practices should be manipulated so that the diet contains sufficient dietary fibre and only limited concentrates. In one study, the incidence rates for displaced abomasum in cows fed 60% and 30% forage diets were 16.7% and 36%, respectively. However, limiting concentrates should not be so extreme that nutritional requirements are not met, as this could negatively affect milk production. In this case, adding sodium bicarbonate at 0.75 to 1% of dietary dry matter is needed to avoid any adverse reactions.
Retained placenta
Retained placentas are defined as the failure of the cow to expel the placenta within 12 hours of calving. Although difficult calving is associated with retained placentas, quite often the cause is nutritional.
Low protein levels (less than 15%) during the dry period have been associated with retained placentas as it causes the placenta to increase in size to absorb sufficient quantities of protein.
Low dietary levels of selenium and vitamin E before calving have also been implicated. Selenium should be present at 6 mg/day. Daily intake of vitamin E during the dry period should be 800-1000 IU. Further, an adequate supply of vitamin A (10,000,000 IU/kg) should be observed because of this vitamin’s role in maintaining the lining of the reproductive tract.
Lameness
Lameness in cattle is one of the key endemic diseases causing health, welfare, and economic problems. Rapid dietary changes contribute to the occurrence of lameness as it causes a shift in rumen microbial populations, which may favour species such as Treponema, which plays a role in digital dermatitis and lameness.
High-quality protein should always be provided as it is required for good hoof structure. Hooves are also composed of fats, which suggests including fat sources in the diet to protect hooves and prevent lameness. Minerals and vitamins are also needed to maintain normal structure and quality of hoof tissues.
Pasture bloat
Pasture bloat is a risk when animals are grazing young, lush pasture, particularly if the pasture has high legume content (clover, medics, or lucerne). In this case, cows produce large volumes of gas during the normal process of digestion, and rumen bloat may then occur unless the gas produced is either belched up or passes through the gastrointestinal tract. Occurrence of pasture bloat should be avoided.
Diarrhoea
Diarrhoea may be caused by faulty diet and/or overfeeding. If the diarrhoea is not severe and the animal is not dehydrating it is better to use tannic acid or commercial diarrhoea remedies. Also, administering clean water or barley water at 2-3 hour intervals helps to compensate body fluid loss.
References are available upon request.
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