Management/Environmental factors

Risk animals

Young or new cows in a herd are especially at risk of contracting infectious diseases but are also more prone to hoof damage. This can be due to bullying by aggressive, older or more dominant cows or from being unaccustomed to using the housing system they are put in to and injuring themselves (particularly in a loose-housed system).

Dry cows are another risk group. As these cows are about to calve, their immunity is often sup­pressed since the body uses all its reserves for the calf. This makes them highly susceptible to infection or hoof damage, particularly sole ulcers. It’s especially critical during this period that these animals have a soft surface to walk and lie on. This will not only prevent the risk of hoof damage, but will encourage them to rest sufficiently, thereby avoiding long periods of standing, and promote increased blood flow to the uterus, which will benefit the foetus. Placing the cows outside on good quality pasture is ideal but if the weather makes this impossible, then a soft bed­ded straw yard, np, can be very effective.

If a dry cow develops a sole ulcer, np, this can often go unnoticed until two or three months after she has calved and is back in the herd, at which point she will be lame. As we saw in the hoof anatomy section, horn grows at roughly 5mm a month and the sole is approximately 10-15mm thick. Therefore it can take 8 to 12 weeks for bruising to emerge, exposing a problem that has been there for weeks or months. If a dry cow or a cow that has just calved has a lame­ness problem she is unlikely to feed properly, which could be detrimental not only for the calf, but also for herself once she is put back into the herd to be milked. Her production is unlikely to be as high as it should, and she could experience a negative energy balance and so lose condition, predisposing her to metabolic problems such as abomasal displacement or ketosis.


Integration and training of heifers

Untrained heifers are often placed straight into cubicle systems after calving, when they are not used to the loose-housed free stall design. They are equally unused to having older, more domi­nant cows around. The result is that they tend to lie less as they are forced out of the cubicles by more dominant cows, and it has been suggested that this can contribute to longer standing times, which may result in subsequent lameness. Another factor affecting heifers is that they often struggle to get to the feed fence, meaning they also stand longer trying to feed.

Heifers and young stock should ideally be trained early on in how to use a barn with cubicle dividers, automatic scrapers, and all the things they will experience in the main cow barn. This way they learn to use a cubicle-based system, including lying in the stalls, walking on concrete or slats, using the feed table, avoiding obstacles like automatic scrapers, thereby avoiding trauma or injury to hooves and reducing stress levels once put into the main herd. Training heifers in a barn with a self-locking feed fence can be useful so that the first insemination can be easily performed (when using artificial insemination) and pregnancy checks can be easily made. Early training, followed by integration, is a good way to help these animals develop relationships within the rest of the herd and fit into the social hierarchy before they have their first calf.

It’s important for a freshly calved cow to increase her feed intake quickly to minimise the duration and effects of negative energy balance. A cow that is completely new to a herd first has to find her place in the social hierarchy. This can make feeding very stressful and result in a lower dry matter intake, a lower yield and very likely an immunity suppression that renders them susceptible to hoof damage as well as mastitis and respiratory problems. If the heifer has already spent some time with the herd before calving, although she may have to re-establish herself somewhat, it should be a much less stressful experience and occur reasonably quickly.

Space, freedom and fear response

Every cow has her own comfort zone and when another animal or human passes the border of this zone she will react by attacking, socialising or escaping. The size of the zone depends on the character of the cow, a calm cow will tolerate a smaller personal space than a nervous one. Heifers need more personal space than older animals. As cows age, they frequently become higher ranking too, so they are no longer afraid of other cows. All herds have a social hierarchy, usually expressed by head butting, pushing or avoidance. Social interactions are an important part of natural herd behaviour, but it’s important to have good conditions in the barn, such as space at the feeding area, adequate water troughs, and enough comfortable cubicles to rest in.

Stocking density and competition

Overcrowding often increases the negative effects of social interactions, with heifers, cows new to the herd and less dominant cows regularly being bullied or placed in aggressive or competitive situations. This results in more sole lesions on the medial claws of their front feet caused by pushing or backing away in an attempt to avoid the more aggressive cows, This places more pressure on the medial claw and often twists it at the same time. Structural damage can also be caused to the hooves in these situations. Plenty of training and space should therefore be given so that the less dominant cows have an escape route and don’t get trapped, panic and injure themselves in the process of fleeing.

Overstocking can also decrease lying time dramatically. As described previously, sufficient ly­ing time is important for the cow to keep her hooves dry and healthy, to rest and ruminate and to increase blood flow to the udder for milk synthesis. This is especially relevant with younger, less dominant cows or heifers, as dominant cows will displace low ranking cows from the stalls, forcing them to stand for longer periods.

Overstocking can also aid in the transmission of disease. Overstocked barns often have a damp, ammonia-type smell, probably exacerbated by poor ventilation and light, but also in­dicative of too many animals in close proximity, whereby fighting disease becomes much more difficult.

As a general rule, cows should have enough space so that they can all feed at the same. time (allowing 60-76cm of space per cow at the feed table), they can all lie at the same time (at , least one cubicle per cow), that cubicles are large enough for them to lunge and rise comfortably (it is recommended that stalls be 245-250cm long) and that they have enough space and sufficient troughs to drink comfortably (there should be 3-4m space around a water trough to reduce aggression).

Stockmanship and farmer behaviour

Many studies describe the effect of an impatient farmer who shouts and uses a stick to hit or a dog to chase cows compared to those who allow the cows to move along at their own pace. In particular, Chesterton’s studies in New Zealand (2004 – 2008) highlight that the incidence of lameness is greater in the grass-based system when cows are forced along tracks too quickly. This is also true of more intensive systems where cows are forced along alley ways and crowded too tightly in the waiting area to be milked. A trained, knowledgeable farmer with a calm nature is far more able to display good stockmanship when tending cows. Cows react well to a calm voice and a relaxed environment and demonstrate lower levels of stress or flight responses. Production is known to be higher and lameness risks lower in these systems.

Knowledge about lameness recognition, causes and preventative techniques, as well as recording and treating cases early, are all examples of expertise necessary for handling dairy cows. Nothing is as valuable as observing your cows on a regular basis as this is will provide you with any signs of poor hoof health or other welfare concerns.

Informacje dostarczone przez DeLaval UK