Table 2. Serum-Se concentrations (ng/mL) in ewes after weekly oral drenching with no Se, inorganic Se (Na-selenate or Na-selenite), and organic Se (Se-yeast) at varying supplementation rates (4.9, 14.7, and 24.5 mg Se/wk; Na-selenate only at 8.95 mg Se/wk) for 62 wk.¹ .

		Oral Selenium Drench										P-value
Se-Source	No-Se	Na-Selenate		Na-Selenite				Se-Yeast
Se-Dosage, mg Se/wk	0	8.95	4.9		14.7	24.5	4.9		14.7	24.5	SEM2	Overall
Week 0
Healthy N3	15	15	15		15	15	15		15	15
LSMean4	108	106	106		94	104	104		99	97	6	0.62
Footrot N5	15	15	15		15	15	15		15	15
LSMean4	90	92	87		89	94	89		92	83	6	0.92
Week 14
Healthy N	19	23	20		21	20	23		19	20
LSMean	62	142	123		162	165	168		217	250	6	<0.0001
Footrot N	10	7	10		9	9	7		9	9
LSMean	66	154	127		160	173	189		205	260	9	<0.0001
Week 27
Healthy N	8	4	4		2	3	6		7	7
LSMean	48	128	129		162	162	142		182	226	15	<0.0001
Footrot N	21	26	26		28	26	23		21	22
LSMean	58	136	120		151	165	147		185	218	4	<0.0001
Week 40
Healthy N	22	14	16		22	11	15		21	17
LSMean	34	139	125		154	172	151		199	236	6	<0.0001
Footrot N	6	14	12		8	17	12		6	11
LSMean	31	141	127		145	160	144		204	243	8	<0.0001
Week 54
Healthy N	18	11	15		21	12	13		10	10
LSMean	35	139	124		156	176	172		221	296	9	<0.0001
Footrot N	9	13	13		9	15	13		17	14
LSMean	46	150	141		166	179	159		221	293	10	<0.0001

¹Adapted from [1]; numbers differ because all sheep are included here and classified as healthy or footrot-affected.

²The largest SEM of the 8 treatment groups is shown.

³Number of healthy sheep in each treatment group.

⁴Least squares means.

⁵Number of footrot-affected sheep in each treatment group.