Table 3.

The relationship between selenium (Se) status and herd measures of production and disease

	Se-marginal herds			Se-adequate herds
Herd measure	n	Mean	s	n	Mean	s	P-value
Milk Se concentration (μg/mL)	32	0.0182	0.003	49	0.027	0.004	<0.00
Herd size (mean cows on test)	31	39	16	47	40	22	0.63
Average DIM	31	182	16	47	178	10	0.26
Average daily milk yield (kg)a	28	27.67	5.12	45	29.77	3.53	<0.01
Milk fat (%)	31	3.82	0.18	47	3.81	0.32	0.88
Protein (%)	31	3.29	0.10	47	3.33	0.12	0.33
Somatic cell countb	31	232	105	47	250	102	0.28
Bulk tank somatic cell countb	28	208	88	46	228	89	0.18
Clinical mastitisc	30	17.5	15.0	46	17.3	12.8	0.84
Services per conception	31	1.82	0.35	47	1.93	0.36	0.21
Average days open	31	152.5	31.0	47	147.3	20.5	0.39
Retained placentac	30	14.9	10.8	47	13.4	8.6	0.89
Uterine infectionc	30	3.3	5.2	45	4.5	6.6	0.37

n — number of herds; s — standard deviation; DIM — days in milk

^aAdjusted corrected milk

^bSomatic cells × 1000/mL

^cCases/100 lactating cows/year, as reported by the farmer