Table 2.

Results of final linear models for serum Se, vitamin E, T4, and T3 concentrations in PEI horses

Outcome	Effect	Category (n)	Estimatea	SEb	P-value
Se	Group	Young pleasure (31)	0.227	0.019	0.001
		Aged pleasure (34)	0.286	0.018
		Racehorses (36)	0.392	0.020
		Broodmares (50)	0.369	0.019
	Season	Winter (Nov, Dec, Jan)	0.421	0.051	0.041
		Spring (Feb, March, April)	0.272	0.020
		Summer (May, June, July)	0.308	0.010
		Fall (Aug, Sept, Oct)	0.303	0.014
Vitamin E	Group	Young pleasure (31)	13.39	0.58	0.001
		Aged pleasure (34)	17.42	0.56
		Racehorses (36)	19.13	0.54
		Broodmares (50)	18.37	0.46
	Se (Group)	Young pleasure	−1.95	19.45	0.010
		Aged pleasure	13.44	11.05
		Racehorses	58.38	17.08
		Broodmares	−7.075	8.713
T4	Group	Young pleasure (31)	5.333	0.171	0.001
		Aged pleasure (34)	4.887	0.163
		Racehorses (36)	3.101	0.158
		Broodmares (50)	3.784	0.139
	Se	n/a	3.830	1.781	0.033
T3	Group	Young pleasure (31)	1.258	0.095	0.784
		Aged pleasure (34)	1.171	0.090
		Racehorses (36)	1.287	0.088
		Broodmares (50)	1.201	0.077

^aRegression coefficients for continuous predictors and least squares means for categorical predictors, computed at the mean Se in the group, when Se is present in the model. The estimates for Se, vitamin E and T4 refer to a square-root transformed scale.

^bSE — standard error.