Other Factors

Feed table

Through continual observation of your cows, you can learn many things about your farm and your animal health. For instance, your cows are straining to reach food it’s likely that they are overloading their front claws, resulting in uneven growth and wear, and also that they are hungry. Cows spend around four hours a day at the feed fence and it’s a good initiative to push feed towards them a few times a day and also to tilt the feed fence forwards slightly (approximately ten degrees) so they can reach the feed table easily. The table should neither be positioned too low or too high, so that cows are forced to get on their knees or to step up to get to the feed. The table should be ideally be around 10-15cm higher than the floor where the cows are standing.

feedtable

Ventilation

It is especially important in a housed system that ventilation is adequate, to help prevent the transmission of disease and to prevent cows suffering from heat stress in the summer. Dairy cows eat and transform feed energy into milk and meat, but they also breathe, defecate and urinate — all of which release moisture and gas into the air. The primary role of any ventilation system is to provide an adequate supply of fresh air inside the barn all year round, to obtain acceptable levels of moisture, gas, dust and odours and also to warm the building during colder months.

Disease

When animals are sick, they shed pathogens, and if these are not expelled by the building’s ventilation system and fresh air, the bacteria will infect other animals, increasing the risks of infectious hoof diseases. Young animals (especially calves), or those calving, have a lower or less developed immunity than older animals, meaning they have little protection and are more susceptible to disease. Areas where these animals are housed should be warm but particularly well ventilated.

Humidity

High humidity in the barn also contributes to higher levels of airborne pathogens that make animals more susceptible to hoof problems and the like. In a well ventilated building, a cow’s coat will be free from moisture.

Dust

Every farm collects dust, consisting of both organic and inorganic material. A large proportion of dust is organic and comes from feed, dried manure, hair and skin, pollen, insect parts, moulds, fungi, viruses and bacteria. At high levels, these particles can be particularly irritating to the respiratory tract and cause breathing problems and coughing. This can cause cows to stand still rather than exercise so they don’t aggravate the respiratory system. This results in reduced blood circulation to the hoof.

Ammonia

Ammonia is released when bacteria decompose the urea in manure. High levels of ammonia in the air can suppress the animal’s immune system, causing reduced growth rates along with respiration problems, increased stress and lower production. Maintaining a barn and manure temperature close to that of the outside air can help limit the release of ammonia.

Insects

Insects are also attracted by barn odours. Insects carry a risk of bacterial and viral transmission between animals, equipment and into the milk itself, so good ventilation is essential to help keep these away.

Heat stress

The effects of heat stress on dairy cow physiology and productivity have been well documented. The first signs of heat stress can be seen at 20°C, where sweating and accelerated respiration may be observed. Heat stress can cause milk yield to decrease by about 10 percent or more, and reduce reproductive performance, while heat stress during late gestation has been reported to reduce birth weight and subsequent milk production. Heat stress is a major health risk as it can dramatically affect hoof health as well as somatic cell count.

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Temperature and humidity combined determine the level of heat stress (TH1 index). In a hot environment, a cow controls her metabolic heat production by reducing her feed intake, which leads to a decline in milk production. Heat stress occurs when a cow’s load exceeds her capacity to lose heat, and as reported by Zinpro, cows exposed to heat have a lower rumen pH than cows exposed to more moderate temperatures.

Shearer and van Amstel (2003) and Grant (1997) explain that this in turn causes metabolic acidosis, vasoconstriction/vasodilation, laminar destruction and weakened claws due to a breakdown of the supportive connective tissues and poor quality horn formation. This leads to an increase in claw lesions and lameness. Cook (2004) found that the incidence of hoof lesions were highest in September and could be the result of heat stress over the previous two or three summer months.

Cook (2004) found that the incidence of hoof lesions were highest in September and could be the result of heat stress over the previous two or three summer months.

graph

 

 Lameness treatment rate by month for 10 herds (Cook 2004)

Bedding treatment

Adding a bedding treatment could help to absorb extra moisture from the barn air as well as beds and help eliminate manure and ammonia smells. This in turn will help reduce insects, raise productivity and reduce ventilation costs.

Worker safety

Poor air quality and high dust levels not only affect the animals but farm workers too, increasing their risk of contracting respiratory diseases or problems, especially in winter. If levels of dust and ammonia are high, workers are advised to wear a mask that covers their mouth and nose to prevent inhalation.

Exercise

Good blood circulation in the hoof is maintained through exercise as the heel and digital cushion force blood to flow around the hoof and out again. Cows that lie down for too long risk their hooves weakening due to the lack of good blood supply and nourishment required for horn formulation. Sick animals should also be encouraged to move around in order to maintain hoof strength.

Although exercise is important, too much exercise can he detrimental to the hooves as this can lead to excessive wear on the soles, which can he easily damaged. As Blowey (1993) describes, lameness in young heifers or bulls introduced to a cubicle shed can often be attributed to this.

Trimming

The goal for regular and functional (preventative) claw trimming is to correct asymmetric claws, equalise weight distribution and reduce the risk of claw lesions and lameness through early detection. Most overgrowth occurs at the toe, preventing the cow from walking naturally and resulting in a short, stiff gait. When the toe is long, the sole at the toe becomes thick, forcing the weight-bearing axis back toward the heel, often resulting in the weight bearing forces being concentrated over the sole and heel ulcer sites. By reducing the toe length and sole thickness with trimming, the weight bearing axis can be moved forward again away from the sole and heel ulcer sites, thereby decreasing the potential for ulcer development. As described by Kloosterman (2004), routine trimming is meant to prevent lameness but, if overdone, lameness can also be caused. It is therefore important to consider the farm conditions when deciding how much trimming is necessary.

 

trimming

trimming2

 

The diagram shows the preventative trimming needed to shorten the claw and trim the abaxial wall. The claw tilts forwards and outwards so that the body weight is shifted in that direction. The claw will then rest more on the wall, where a strong vertical connection helps to absorb the force of the body weight. This means the corium in the sole is loaded more evenly and less heavily.
Source: Toussaint — Raven (2003).

In the case of lameness, curative trimming is often necessary in order to transfer the weight hearing from the painful claw to the healthy one. Overgrowth, overburdening and altered weight bearing mean that the claws of dairy cows re­quire regular evaluation and trimming. In some cases, the rate of horn wear is in balance, with the rate of horn growth, despite the effects of weight bearing, and trimming is not required. In other cases, horn growth exceeds the rate of wear and trimming is required to correct weight bearing disparities. In free stall-housed dairy cattle, the wear rate often exceeds the growth rate and trimming only exacerbates an already serious problem. Good foot care and claw trimming requires an understanding of the anatomy of the foot and the dynamics of claw horn growth.

It is recommended that claws are checked at least two or three times a year and trimmed if necessary. This is normally done just before cows are dried off, two or three months post-parturition and once more if required. You can trim the whole herd at once, trim in groups or practice individual trimming. Only an experienced individual should trim the hooves, using sharp tools as well as restraint equipment to prevent injury to both person and animal.

hoofcare

 

Information kindly provided by DeLaval UK