PROGRAMA EDUCATIVO “UNIDOS CONTRA LA ANEMIA” (ANEXO 02).

P. Plate

Damory Veterinay Clinic, Edward Street, Blandford, Dorset, United Kingdom.

Introduction

Organic production standards encourage “positive health” and restrict or prohibit certain conventional measures of disease prevention. The author’s personal approach to mastitis control and fertility problems in dairy cows and trace element problems and worm control in sheep is outlined, and it is discussed if organic standards, as a whole, promote or inhibit animal health.

Mastitis control in dairy cows

The herd and mastitis management

In a well managed organic herd, the breed was changed during organic conversion, from Holstein to crossbreeds, including Ayrshire, Swedish Red and Brown Swiss. As antibiotic use is restricted and prophylactic antibiotic dry cow treatment prohibited, those changes were necessary, especially considering that half of the cubicles were about 40 years old and too small for Holstein cows (2.10 m long against the wall).

About 100 cows are now yielding an average of 7,000 litres per annum and fed solely on grass/grass silage and cake in the parlour. The farm is a family enterprise, run by two brothers who are excellent stockmen, know their cows and detect any problems at an early stage. Basic routines in the parlour are dry wiping before milking and teat spraying after milking. After a high cell count cow or a mastitic cow, the cluster is dipped in paracetic acid, which is known to have a fast disinfectant action. The cubicles are straw-bedded, without additives like lime etc.

Cows are dried off abruptly. Problem cows with high cell counts receive antibiotic dry cow treatment, as this is the most successful period for treating existing intramammary infections. The majority of cows (88 %) are dried off with an internal teat sealant only.

Success of the programme: cell counts

Somatic cell counts were low just after conversion, which was expected, as the whole herd was in the first lactation. While everyone expected a rise in cell counts with the herd aging, this was practically not the case (Table 1)

Table 1: monthly somatic cell counts

Success of the programme: mastitis incidence

The cow incidence of mastitis was satisfactory in the first recorded year (32%), and decreased slightly to 30 % in the second year, in spite of the herd being older. These figures are below the national average in the UK, which is around 40% or higher and among the lowest in the practice. A few cases of dry cow mastitis occurred before the internal teat sealant was available. None of these were summer mastitis, as the original calving pattern was chosen to avoid having dry cows during the main fly season. With the introduction of the internal teat sealant, dry cow mastitis has disappeared completely.

In the previous 12 months, not a single case of mastitis occurred in first lactation animals (n=11), the incidence for second lactation animals was 17% (n=46) and for third lactation animals 50% (n=46). This pattern confirms that contagious mastitis dominates the picture, which is backed up by bacteriology (Staphylococcus aureus isolated from samples from the majority of problem animals).

Treatments and evaluation

Attempts to treat mastitis with homeopathy were disappointing. Although some cases cleared clinically, most cases recurred later, and we hardly noticed any cell count response. For that reason, and knowing about the importance of early intervention, antibiotic treatment is first choice for clinical cases. Bulk tank and individual cell counts show a high success rate with

regard to cell count response. Four out of five Staphylococcus aureus cases were cured, two at drying off and two in lactation. Systemic antibiotics were only used in six cases in the last two years, so the amount of antibiotic used remained low. Most cases were treated once a day for three days with a standard intramammary tube.

The superior success rate is apparently due to

- the two year’s break in milk production (=all in, all out system), with resistant bacteria having disappeared;

- the overall low use of antibiotics causing low selection pressure for resistance; and - early detection and prompt treatment.

Conclusions

Compared with most conventional farms, the example farm showed - low incidence of mastitis;

- low use of antibiotics;

- better response to antibiotics when used; and - excellent milk quality status.

Further room for improvement could be identified in:

- selection of cases for therapeutic antibiotics (quick test to show if gram+ or gram-); and - better choice of homoeopathic remedies.

Fertility in dairy cows

One constraint on organic farms is the lack of maize silage as a complementary forage to grass silage. Possible alternative is the whole crop silage, but market forces (good price for organic grain) make this rare in the UK. As a result, many grass-land based organic farms have to buy in energy feeds. A high amount of metabolisable energy in some of these cakes may come from oil, while fermentable energy (sugars and starch), necessary to utilise the protein in grass, may be lacking.

As a result of the energy problem, many animals, especially heifers, struggle to keep milk proteins up with increasing yields (Figure 1)

Figure 1: Protein against milk yield

Within these constraints, the following fertility parameters were achieved in the example herd:

- Calving interval: 390 days

- Conception rate: 50 %

- Culling for fertility: less than 50 % of overall culling

- Overall culling rate: 15 % (but young herd, most cows in third lactation)

- % positive at pregnancy diagnosis: 70%

Again, the parameters suggest that good stockmanship and heat observation can compensate for some constraints on farm. Fertility in the overall national herd is declining rapidly, with the overall conception rates below 40 %, calving interval above 400 days and overall culling rate at around 30%. Higher yielding cows with no genetic selection for fertility parameters, combined with more cows per stock person and similar labour constraints on forage harvest and conservation, all lead to this decline, which make the value of organic principles more and more obvious. Many farmers see marketing and achieving acceptable milk prices as a much bigger challenge than technical and animal health problems on farm. Solving the milk price problem will have positive health implications as the “need” to cut corners disappears and long overdue investments in buildings etc. can be made.

Fertility treatments

The vast majority of fertility treatments are carried out using homoeopathy. Fertility is a good area to start using homeopathy in, as the success or failure has limited welfare implications. To assess the success, placebo controlled studies have to be carried out, as time alone “cures” many acyclic cows when they have passed the negative energy state.

Vaccination

Bovine viral diarrhoea vaccination was introduced about 12 months ago, following some embryonic losses and high titres in bulk milk and young stock. However, this is reviewed on an annual basis, as the clinical impact has still to be proven: Calf health was good before and after the start of vaccination, and conception rates have remained stable. Leptospirosis vaccination is carried out annually, as the turnout to wet fields bears a risk of abortions. As lungworm problems have occurred in the past, oral vaccination is given to the youngstock before first turnout. During conversion, egg counts in the summer and serum pepsinogen levels at housing have been investigated. They revealed no significant worm burden, so that worming (strategic or therapeutic) was never carried out.

Trace element problems and worm control in sheep

Many organic as well as non organic sheep farmers have their animals monitored for trace elements on a regular basis. Deficiencies can cause poor growth and a higher susceptibility to infectious and parasitic diseases. Unquestioned supply of trace elements has lead to cases of toxicity, in sheep as well as in cattle. Ewes in mid pregnancy, fed entirely on grass or conserved forage are the main candidates for blood sampling, but growing lambs can be sampled as well. The value of blood copper levels is under discussion. Liver copper levels, if available, would be the diagnostic “gold standard”.

As for worm control, the approach of egg counts and worming as necessary is increasingly used in conventional farms to avoid unnecessary costs and wormer resistance. Worming in regular fixed intervals is now seen as bad practice. In organic farming, lower stocking rates, evasive grazing practices and – hopefully in the near future– genetic selection are encouraged and will reduce any worm burden. Most organic farmers still worm ewes at lambing to prevent pasture contamination. Certain endoparasites (Nematodirus, fluke) make a strict “test and worm as needed” approach difficult, as severe clinical signs can be caused by immature/larval stages. On problem farms, strategic treatments may be given, based on farm history.

Cases of resistance against all three classes of wormers have recently been reported in the UK, with the recommendation to cull the flock, plough the fields and keep them free of livestock for several years. Wormer resistance has made sheep farming impossible in some parts of the world. New UK guidelines to avoid wormer resistance are a big endorsement of organic principles. They include:

- Farm history and treatment of incoming stock if necessary; - Minimise wormer use, do egg counts before worming; - Test for resistance;

- Leave some animals untreated to maintain a population of susceptible worms, especially when turned to clean pasture; and

- Ewes with singles, especially when older, do not usually require routine treatment. Their contribution to pasture contamination is minimal.

Overall conclusions – does organic farming cause animal health problems?

Conventional farming faces increasing problems and adopts more principles which have been used on organic farms for decades. Selective dry cow therapy and selection for antibiotic mastitis treatment in dairy cows and a “test and treat as needed” approach for trace element supplementation and worm control are examples of this.

However, animal health problems on organic farms do occur, due to

- misinterpretation of the standards;

- general neglect and poor stockmanship; and

- bad luck (movement restrictions due to TB, FMD etc.).

The UK certification bodies are working to minimise these problems in following ways:

- the standards are revised, with the emphasis on being understandable, and training for farmers and vets is given;

- animal-based welfare assessment as part of the inspection process is currently under discussion; and

- a sympathetic approach with limited derogations is given to farmers who face exceptional problems.

I would like to conclude by saying that I have not encountered any health problems which are solely due to the organic farming system.

Part B: