Table 1. Fertility status of Holstein bulls.

Bull #	Bull number	Fertility status	Number of breedings	Conception rates % difference from average	Std of difference	Conception rates (%)
1	011HO10489	HF	5293	5.42	2.02	45.3
2	011HO11422	HF	825	5.1	1.90	40.4
3	011HO11436	HF	2032	4.8	1.79	40.3
4	011HO9748	HF	6378	4.6	1.67	44.4
5	011HO9212	HF	779	4.4	1.75	38.8
6	011HO11351	HF	2487	3.59	1.34	45.7
7	011HO11312	HF	5751	3.56	1.33	39.8
8	011HO9247	HF	1849	3.7	1.32	44.4
9	011HO11226	LF	1604	-3.75	-1.40	35.7
10	011HO11276	LF	2276	-4.06	-1.52	37.8
11	011HO11264	LF	967	-4.49	-1.68	34.4
12	011HO9354	LF	704	-5.6	-2.59	24.0
13	011HO9623	LF	747	-6.3	-2.91	26.7
14	011HO10928	LF	5603	-6.76	-2.52	34.6
15	011HO9415	LF	722	-7.5	-3.35	22.1
16	011HO11459	LF	674	-10.61	-3.96	23.3

Bulls 1 to 8 were defined as high fertility (HF) and bulls 9 to 16 were grouped as low fertility (LF). Fertility of each bull was expressed as the percent difference of its conception rate from the average conception rate of all bulls. Probit.F90 software was used to estimate fertility.