. 2022 Mar 31;3(3):212–216. doi: 10.3168/jdsc.2022-0212

Table 1.

Pregnancy per AI (P/AI) 31 d after timed AI (TAI) according to the strategy to initiate the TAI protocol, farm, parity, milk production, and number of AI

Item	Overall	Strategy to initiate the TAI protocol¹			P-value²
Item	Overall	EBd0	EBd0-GnRHd0	EBd0-GnRHd2	T	V	I
Farm
1	33.4 (137/398)	29.5 (55/161)	31.2 (40/125)	39.8 (42/112)	0.24	0.35	0.78
2	36.6 (156/432)	31.3 (43/134)	37.8 (54/147)	41.1 (59/151)	0.26	0.35	0.78
Parity
Primiparous	40.0 (149/371)^x	35.3 (54/140)	43.2 (52/119)	41.7 (43/112)	0.46	0.005	0.27
Multiparous	30.3 (144/459)^y	25.9 (44/155)^b	26.6 (42/153)^b	39.2 (58/151)^a	0.03	0.005	0.27
Milk production, kg/d
<33.5	33.2 (187/540)	30.6 (65/190)	35.4 (64/178)	33.7 (58/172)	0.65	0.32	0.16
≥33.5	36.8 (106/290)	30.1 (33/105)^b	33.5 (30/94)^b	47.6 (43/91)^a	0.04	0.32	0.16
Number of AI
First service	32.7 (98/294)	24.6 (21/86)^b	34.1 (35/103)^ab	40.6 (42/105)^a	0.04	0.20	0.25
Later services	37.3 (195/536)	36.9 (77/209)	34.8 (59/169)	40.4 (59/158)	0.64	0.20	0.25

^a,b

Least squares means with different superscripts within a row are different (P < 0.05).

^x,y

Least squares means with different superscripts within a column are different (P < 0.05) considering the main effect of the specific variable (farm, parity, milk production, and number of AI).

Treatments were estradiol benzoate (EB) on d 0 (EBd0), EB plus GnRH on d 0 (EBd0-GnRHd0), or EB on d 0 and GnRH on d 2 (EBd0-GnRHd2) of the TAI protocol.

T = effect of treatment within class of cows; V = main effect of the variable (farm, parity, milk production, and number of AI); and I = interaction between treatment and variable.