Table 1.
Effect of BCS near AI on pregnancies per AI (P/AI) and progesterone (P4) concentration at first GnRH injection (G1) of the breeding Ovsynch protocol
| Item | BCS at AI1 | P-value | |||||
|---|---|---|---|---|---|---|---|
|
|
|
||||||
| ≤2.5 | 2.75 | 3.0 | ≥3.25 | BCS | Parity | C12 | |
| % of cows (no./total no.) | 23.6 (260/1,103) | 31.1 (343/1,103) | 23.5 (259/1,103) | 21.8 (241/1,103) | |||
| All cows | |||||||
| P/AI at 32 d [% (no./total no.)] | 40.4 (105/260)b | 48.1 (165/343)ab | 47.9 (124/259)ab | 52.3 (126/241)a | 0.10 | 0.003 | 0.03 |
| Cows with 2 pregnancy diagnoses | |||||||
| P/AI at 32 d [% (no./total no.)] | 42.3 (70/171)b | 52.4 (94/185)ab | 49.7 (53/107)ab | 54.8 (86/159)a | 0.12 | 0.02 | 0.03 |
| P/AI at 70 d [% (no./total no.)] | 34.5 (59/171)b | 44.0 (81/184)ab | 43.0 (46/107)ab | 50.3 (80/159)a | 0.05 | 0.008 | 0.02 |
| Pregnancy loss [% (no./total no.)] | 15.7 (11/70) | 12.9 (12/93) | 13.2 (7/53) | 7.0 (6/86) | 0.40 | 0.19 | 0.31 |
| Mean P4 concentration at G1 (ng/mL) | 2.29 ± 0.12b | 2.63 ± 0.13a | 2.80 ± 0.14a | 2.75 ± 0.11a | 0.04 | <0.001 | 0.004 |
| Proportion of cows with P4 concentration | 12.3 (21/171)a | 8.1 (15/185)ab | 2.8 (3/107)bc | 2.5 (4/159)c | 0.006 | 0.14 | 0.0008 |
| <0.5 ng/mL [% (no./total no.)] | |||||||
| Cows with P4 concentration ≥0.5 ng/mL | |||||||
| P/AI at 32 d [% (no./total no.)] | 43.3 (65/150) | 51.8 (88/170) | 50.0 (52/104) | 53.5 (83/155) | 0.34 | 0.04 | 0.10 |
| P/AI at 70 d [% (no./total no.)] | 36.7 (55/150) | 44.6 (75/169) | 45.4 (46/104) | 49.7 (77/155) | 0.19 | 0.01 | 0.06 |
| Pregnancy loss [% (no./total no.)] | 15.4 (10/665) | 12.5 (12/87) | 11.5 (6/52) | 7.2 (6/83) | 0.48 | 0.16 | 0.34 |
a–c
Values within a row with different superscript letters differ at P < 0.05.
1
Cows had their BCS evaluated near AI using a 5-point scale with 0.25 increments.
2
Preplanned contrast between low (≤2.50) and high (≥2.75) BCS near AI.