Herbage yield and animal production from grassland on three commercial dairy farms in South-East England

Yields of grass were measured on three dairy farms in 1981. Farm 1, on free-draining loamy soil over chalk, produced 10.3 t DM ha⁻¹ using 336 kg N ha⁻¹. Farm 2, on poorly-drained loam over Oxford clay, produced 12.8 t DM ha⁻¹ using 354 kg N ha⁻¹. Farm 3, on loam over clay with some free-draining sandy loam, produced 9.5 t DM ha⁻¹ with 169 kg N ha⁻¹. Allowing for differences in soil nitrogen and summer rainfall these yields were quite close to expectations from experimental results, despite considerable poaching damage to some swards.
Animal production records were kept and all livestock were weighed every 6 months, so as to calculate the utilized metabolizable energy (UME) output from grassland on each farm. These were 73, 62 and 59 GJ ha⁻¹ on farms 1, 2 and 3 respectively.
The UME output, expressed as a proportion of the yield of grass (converted to ME), was taken as the 'efficiency of utilization' of grass. This was 70% on farm 1,44% on farm 2 and 58% on farm 3. Results are presented separately for the summer and winter 6 months. Utilization by grazing appeared to be markedly reduced under very wet soil conditions. Major losses occurred in the conservation of grass.
The results begin to establish a valuable base of data from commercial farms.