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Farmers’ Focus November 2018

Young Stock

Lepto: By now all spring and autumn-born calves should have had their first and possibly second lepto vaccinations, with the third due in your “Annual Lepto Vaccination Month” If not, get them done ASAP.

Copper: Historically copper deficient farms are again deficient. As the calf copper levels are similar to those of their dam at birth, we will be seeing more copper problems in young stock if this is not addressed. Copper boluses are a very effective way to maintain copper levels in growing stock. These come in various ranges depending on the weight of the animal and last for 6-9 months

Rough-coated calves may have worms, be copper deficient, or have facial eczema in a couple of months – it is important to know which!  Bloods and faecal samples will tell you which is the problem.

Worms: With conditions finally starting to warm up, larval survival on pasture will be quite good, so tight worm control until it stays hot and dry will improve young stock performance.

It is important to use COMBINATION drenches / pour-ons on cattle under two years of age.

These animals are the ones producing most of the eggs/larvae on your pasture, as they have not yet built up immunity to suppress egg production.  If you use a   single active – eg Cattle Pour, Cydectin, Eprinex etc, you will hasten the development of drench resistance on your properties. Cooperia is usually the first worm type to cause  problems, as the “mectin” family are not as efficient at killing this worm type as good old levamisole – the second ingredient in the combo drenches.

The triple combination drench Matrix-C (or Iver Matrix Calf in cattle <120kg) is the gold standard oral drench in young stock.

How Do Worms Affect Our Stock?

The nature and extent of damage inflicted on the host vary tremendously for different parasites.

Types of damage may be classified into five basic categories:

Mechanical

Physical damage may be produced in several ways. Feeding or invading parasites may destroy tissue and cause wounds. This is accomplished in the stomach by Ostertagia ostertagi and results in digestive upsets, appetite loss, slow weight gain or weight loss.

Mechanical damage also occurs when parasites cause obstruction. Such obstruction may occur in the small airways of lungs infected by Dictyocaulus viviparus. The function of obstructed organs is impaired – pneumonia and lung collapse may be caused by lungworm obstruction.

Digestive

Parasites may destroy host cells and tissues by enzymatic digestion. Ostertagia is a very serious parasite of cattle because it destroys cells from the stomach that secrete digestive juices.

Depletive

Parasites absorb food that the host has already ingested for its own use. This is typical of and some roundworms. Growth of the host is decreased as a result of lost nutrients.

Allergenic

Chemical components of parasites, especially those from ascarids, are foreign to the host and can cause allergic reactions. Allergy is also caused by Strongyloides larvae penetrating the skin of cattle, sheep, and pigs. The result is an intense itching,   particularly of the feet.

Anaemic

Blood lost from the host must be replaced. When there is continual blood loss, body stores of iron– essential for the production of blood– become exhausted. If lost blood is not replaced, iron-deficiency anaemia occurs. Parasites cause this in two ways. First, they ingest large amounts of blood from the host. In addition, some parasites have special anti-clotting agents which are released into the wounds caused when feeding. When the parasites move to other sites, bleeding continues because of these anti-clotting agents. Iron-deficiency anaemia is typical of infections by Fasciola hepatica, and Bunostomum.

Often, the damage inflicted by a parasite is a result of a combination of these disease processes. Infective larvae of Ostertagia ostertagi, for example, cause mechanical, toxic, and possibly allergic  reactions in the wall of the abomasum, causing cells to die rapidly. Continuous erosion means that replacement tissue formed does not have time to mature completely. Body fluid leaks through the damaged gut wall into the abomasum. Food cannot be properly digested, so absorption is impaired. The end result is diarrhoea. Also, the fluid lost from blood into the gut contains much albumin, which is largely responsible for the ability of the circulatory system to reabsorb water from body tissue. In ostertagiasis, the decreased blood albumin causes fluid accumulation in tissues, a condition called oedema. The most common sites for the accumulation of fluid are under the lower jaw (known as bottle jaw) and in the abdomen (know as ascites).

Blood albumin is also lowered in liver fluke, (Fasciola) infections because mechanical irritation to the bile ducts of the liver  allows fluid leakage. Diarrhoea is not usually seen, but bottle jaw does develop.

Loss of blood proteins and the inability to use nutrients place stress on the host. In addition to infected cattle not being able to utilise feedstuffs efficiently, they must replace lost blood elements simultaneously. Under such conditions, animals are less capable of growing and may even lose weight.

Larvae of Nematodirus or Trichostrongylus irritate and damage the intestine and impair the ability of the intestine to absorb water, causing diarrhoea. Mixed infections are common but in different regions there may be fairly defined successions of  species.

My message here is that if you want the best advice on animal health then come see us for the right product.  

The above article is courtesy of Merial.

Medicated Teat Wipesenvironmental mastitis

There have been issues raised by dairy shed auditors on the use of medicated teat wipes when treating  clinical cases of mastitis. Claims have been made that the teat wipes are being used off label which contravenes legal requirements.

Medicated teat wipes supplied with lactating and dry cow therapy products should only be used to disinfect teats:

Þ After milking and immediately prior to treatment with a lactational mastitis intramammary product as this is in the best interests and   welfare of the cow

Þ Immediately prior to the insertion of a dry-off  antibiotic or teat sealant intramammary product.

Medicated teat wipes must not be used to clean teats prior to milking when   supplying that milk for human consumption.

BVD

We have seen BVD virus cropping up in several herds this season. If the virus is cycling in your herd during mating this year for the first time, the number one  suspects will be the  heifers that have just entered the herd. Rapid testing of this group, and removal of any positive animals, will reduce the damage that  may occur. Testing of next year’s calf crop to ensure no carriers were produced will be a key part of control.

With bulls about to enter herds in the not too distant future please ensure they are tested and vaccinated. Biosecurity is at the forefront of many of our minds, so why not take the opportunity to futureproof against BVD. Outriggers or double fencing boundaries will help reduce the chance of ‘over the fence’ spread. Careful selection of where any young and or dry stock graze off farm is important.

BVD is a complex disease. If you have any concerns, sit down with one of the Farm Vet team, and discuss your situation with them.

There is more information at  www.controlbvd.org.nz/home.