Table 2. Akaike Information Criterion (AIC) of body weight (BW) and withers height (WH) for Thoroughbreds growth curve models. Data of Thoroughbred foals is divided by their birth months.

Birth month	Models1	AIC2
		BW		WH
		Colts	Fillies
Jan	d shifting	1,778	770	493
	no shifting	1,793	799	492
Feb	d shifting	9,183	9,418	3,754
	no shifting	9,391	9,550	3,729
Mar	d shifting	12,430	11,205	3,976
	no shifting	12,506	11,229	3,978
Apr	d shifting	8,121	13,585	4,695
	no shifting	8,058	13,648	4,726
May	d shifting	9,093	6,639	2,585
	no shifting	9,013	6,837	2,616
Jun	d shifting	4,904	5,462	923
	no shifting	5,100	5,598	1,052
Total	d shifting	45,675	47,157	16,535
	no shifting	46,068	47,707	16,673

¹ Growth curve models with d values based on birthday (d shifting) or with d=81 (no shifting). ² The smaller value of AIC with boldface and italic fonts indicates better fit of growth curves to the corresponding data within birth month.