Table 1.

Pasture yield, grass cut height, iodine (I) and selenium (Se) content in the natural pasture offered to ewes grazing in the Basalto Region in the northwest of Uruguay.

Scale-pointa	Days prior to lambing
	30				0
	Pasture yield (kg DM)	Grass cut height (cm)	I (mg/kg DM)	Se (mg/kg DM)	Pasture yield (kg DM)	Grass cut height (cm)	I (mg/kg DM)	Se (mg/kg DM)
1	380	4.5	0.60 ± 0.10	0.07 ± 0.01b	242	3	0.60 ± 0.13	0.11 ± 0.01 a
2	2122	8.4	0.56 ± 0.12	0.09 ± 0.01b	2745	8	0.60 ± 0.09	0.16 ± 0.02 a
3	3133	18.3	0.58 ± 0.10	0.09 ± 0.01b	3282	17.7	0.58 ± 0.10	0.14 ± 0.01 a
4	4867	23	0.50 ± 0.11	0.07 ± 0.01b	6808	26	0.56 ± 0.11	0.16 ± 0.01 a

Data are mean ± SEM of three samples. DM = Dry matter. a,b: means significant difference between 30 and 0 days prior to lambing by Student test (p < 0.05).

^aExtracted from “The comparative yield method” by Haydock and Shaw (1975). It is based on a comparative yield method, which estimates the pasture yield from the yields of random quadrats rated to a set of reference quadrats preselected to provide a scale which is available for reference throughout sampling. In this work four reference quadrats were selected (considering height and density of pasture), which constitute the yield scale against which the yields of sample quadrats are rated.