Effect of Facial Eczema on Production
Whatawhata trials (Sheath and Webby APS 1987), Rex Webby and Neale Towers
Each 100 unit increase in GGT meant a:
Flock mean GGT in range 150 to 250 this meant 12% more cull or dry ewes and 14% less ewes lambing multiples.
Also an effect on lamb weaning weight is observed. For example:
Approximate relationships between GGT and lamb production
|GGT||Expected drop in lambing %||Drop in wool production||Drop in weaning wt||lost income per ewe@ 100% lambing||100||2.4 to 11.4||0.6%||0.6kg||$3.30||200||4 to 15||1.5 %||1.4kg||$4.30||300||12 to 18||2.6 %||2.6kg||$8.98||400||14 to 30||2.6 %||2.6kg||$11.33|
The effect on wool production and lamb weaning weights becomes confounded, as GGT increases, by the fact that there are fewer multiples and more dry ewes.
Interpretations of categories of damage based on GGT level vary but these may help: