8 December 2000




A major four-year comparison

of two very different organic

milk production systems

is underway in Wales.

Robert Davies reports

WHICH system is best for organic producers – and can cows be milked successfully on a diet that is almost all home-grown? Thats what the trial at Trawsgoed aims to find out.

The MAFF funded Institute of Grassland and Environmental Research project is also linked with other organic farms monitored by the Welsh Institute of Rural Studies in Aberystwyth. Composite results published at the end of the trial should provide existing and would-be organic producers with a comprehensive overview of the potential of alternative systems.

The main project is based at IGERs Ty Gwyn Farm, which is a 94ha (225-acre) unit located south east of Aberystwyth at Trawsgoed. The farm completed conversion from a conventionally managed unit with a fertiliser input of 380kg N/ha (304 units N/acre) in 1994.

Until October 1998 a single herd was managed organically. At first stocking was cut from 2 cows/ha (0.8 cows/acre) to 1.5 cows/ha (0.6 cows/acre), but the establishment of a sound crop rotation and improved performance of the permanent pasture allowed the rate to creep up to 1.8 cows/ha (0.7 cows/acre).

In year one of the rotation an Italian ryegrass/red clover ley was undersown under a cereal crop, which was either combined or harvested as whole-crop. For the next two years the ley provided three silage cuts a year. In the fourth year a spring cereal was sown for grain, followed by a five year perennial ryegrass/white clover/ herb ley for conservation and grazing.

By the third year after conversion milk production averaged 10,073 litres/ha (4080 litres/acre) and 6105 litres/cow. Home-grown grazed and conserved forage contributed 84% of annual feed requirement and concentrate use averaged 0.22kg/litre.

Splitting unit

The current MAFF research contract involved splitting the unit according to land type into two similar farmlets. The herd was also divided to create two, each with equivalently aged cows, producing similar yields of similar quality milk. Even slurry produced by each of the two groups is separated and spread only on its designated area of land.

In herd A the target yield is 5000 litres/cow from 60 head stocked at less than 1.4 cows/ha (0.56 cows/acre). About 0.5t/cow of concentrates will be fed on what is described as a "minimal or no purchased feed system", which is based on growing grain and protein rich crops to balance high forage diets.

The rotation includes a mixture of reseeded perennial ryegrass/ white clover leys and permanent pasture, perennial ryegrass and white clover leys, cereal grain crops, high protein crops such as pure stands of red clover, and a mixture of Italian ryegrass and red clover.

Possible balance

"We are looking at the possibility of being able to balance energy and protein just using home produced crops," says Richard Weller, IGERs organic herd project leader. "If we are forced to buy in protein we will probably go for field peas or beans.

"We hope to avoid purchasing high priced organic grain, and be less vulnerable to organic feed market price changes that are inevitable as the limit on the acceptable percentage of non-organic feed falls. Because less feed will be bought in we will closely monitor the impact on soil nutrient and trace element levels."

Herd B is stocked at about 1.75 cows/ha (0.71 cows/acre). It is expected to produce an average of more than 6000 litres/cow from home-grown forages and about 1.5t of purchased concentrates. It is anticipated that the phosphate and potash contained in concentrates and straw will keep soil levels stable.

Eleven months after the start of the project the rolling average of herd A was 4905 litres, with 3785 litres from forage. Fat and protein percentages were 4.08 and 3.38, and an average of 99.2% of the diet was home-grown. Margins over purchased feed were £1333/cow and 28.1p/litre.

In herd B, 2900 litres of the 5595 litres rolling average was from forage. Milk fat and protein averaged 4.05% and 3.3%. About 80% of feed was home-grown, leaving margins over purchased feed of £1473/cow and 26.7p/litre.

"It is early days yet, but we have already seen that cows lose a lot of condition if supplementary feeding is stopped when the self-sufficient herd is turned out, with obvious health, welfare and fertility implications."

Dr Weller says the condition loss is particularly true of high genetic merit cows. In the longer term he believes that organic milk producers operating forage based systems will concentrate on breeding a type of cow, possibly a cross-bred or composite, that can perform well and stay healthy.

Both herds calve all year round and are in Bactoscan band A. Early results show that herd A has a rolling cell count of 234,000 cells/ml, and is producing 5.9 cases of clinical mastitis and 10.9 cases of lameness/100 cows. Herd Bs figures are 319,000 cells/ml, 12.7 cases of clinical mastitis and 19.6 cases of lameness/100 cows.

Regulations now dictate that any cow receiving three antibiotic treatments for whatever reason cannot stay in the herd. The herds health plan is based on individual cow care, impeccable hygiene, and spotting problems early enough to allow the use of alternative treatments. &#42

Herd A – minimal or no purchased feed system, with about 99% of diet home-grown. Growing grain and protein rich crops to balance high forage diets.

Herd B – home-grown forage plus about 1.5t/cow of purchased feed – about 80% of diet home-grown.

Richard Weller is trying to find out which system is best for organic producers.

See more