Spelling pastures
To build resident populations of subterranean clover in hill country pastures, sheep farmers are encouraged to spell selected areas for four to five weeks over late spring and early summer if possible.
I tried AberHSG in 2005 shortly after it became available and while the cows find it palatable enough, like most farmers we find it well behind the more modern NZ ryegrasses for winter/spring production and substantially behind a well managed perennial tetraploid for palatability. However, it is the claims made by Dr Alison with regard to AberHSG being environmentally friendly that cannot go unchallenged.
It is true, in theory, that a higher carbohydrate (starch/sugar) forage provides the energy to give better utilisation of high levels of protein in pasture and therefore less wasted in urine. The trouble is, AberHSG has proven to be poor in this area, as shown by research from 2006-08 by Pacheco et al of the Food, Metabolism and Microbiology, Forage improvement, Applied Biotechnologies Group, Agresearch Grasslands and Institute of Veteriniary, Animal and Biomedical Sciences at Massey University .
Their report, “Seasonal and Dietary effects on the concentration of urinary N from grazing dairy cows” reports how three ryegrass cultivars: AberHSG, old tetraploid Italian Moata, and the diploid perennial Impact compared. To summarise, AberHSG gave a urine N average of 6.4g/L in autumn compared to Impact at 5.5g/L and Moata at 4.5g/L. In spring, AberHSG gave a urine N average of 5.1g/L, Impact 4.9g/L, Moata 2.9g/L. The significantly lower N concentration from Moata will be partly due to the
