Stocking rate reduction will safeguard heather
Stocking rate reduction will safeguard heather
ADOPTING stricter limits on stocking rates within the Environmentally Sensitive Area scheme increases lamb performance and gross margins, but these benefits are only short term, according to research.
Speaking at the BGS and BES meeting, ADAS researcher Sarah Hetherington said the substantial increase in sheep numbers over the last 40 years has led to a decline in heather area.
"In response, ESA schemes were established to support lower stocking rates. There are two levels in the scheme, one aimed to maintain heather with a moderate reduction in stocking rates and a more drastic tier to enhance heather with larger cuts."
But there has been little work to determine the impact of this scheme on sheep performance and heather areas. Since 1990, a series of DEFRA-funded studies at ADAS Pwllpeiran involved setting up two farmlets of about 150ha (362 acres) stocked with Welsh Mountain sheep at either 1.93 or 1.8 ewes/ha, said Dr Hetherington.
"Reducing stocking rates from 1.93 to 1.8 ewes/ha (0.78 and 0.73 ewes/acre) increased lamb weights at weaning by 1.1kg. However, these differences tended to decrease with time, there was little difference in lamb weights by the end of the study."
Dr Hetherington believes this reflects a gradual change in vegetation with reduced stocking rates resulting in less forage. Similarly, differences in gross margins between the two farmlets also decreased over the same period.
Before this decrease, gross margins were about £10/ha (£4/acre) higher for the lower stocking rate. This is despite tier 2a having higher variable costs due to purchasing extra concentrates (see table).
Gross margins for both systems are higher than the average MLC value showing that the level of payment was sufficient to compensate for lost income. However, more than 84% of the margin for tier 2a comprises of ESA payment, she added.
"While the scheme compensates for lost income, the main aim is to enhance heather area. Heather plants were visibly improved, but there was no increase in heather cover." *
Cost comparison
Tier 1a Tier 2a
Stocking rate (ewes/ha) 1.5 1.0
Variable costs (£/ewe) 16.5 18.2
Replacement costs (£/ewe) 2.5 2.3
Gross margin
£/ha 97.9 107.9
£/ewe 55.7 64.6