Table 5.
Effects of prepartum diet on GnRH-induced LH release during early postpartum
| Week 1A | Week 2A | P | ||||||
|---|---|---|---|---|---|---|---|---|
| Control | Canola | Sunflower | Control | Canola | Sunflower | TrtB | Trt*wkC | |
| Cows (n) | 5 | 5 | 5 | 6 | 5 | 5 | ||
| LH Mean (ng/mL) | 1.14 ± 0.14 | 0.84 ± 0.23 | 0.96 ± 0.21 | 2.42 ± 0.21¥a | 1.66 ± 0.23b | 1.83 ± 0.18¥ab | 0.03 | 0.05 |
| LH- Peak (ng/mL) D | 2.05 ± 0.75 | 3.21 ± 0.80 | 2.19 ± 0.70 | 5.14 ± 0.80 | 4.07 ± 0.73 | 3.72 ± 0.73 | 0.37 | 0.11 |
| LH-Peak-time (min) E | 32.50 ± 13.26 | 48.00 ± 13.78 | 22.50 ± 10.27 | 81.37 ± 21.53 | 101.63 ± 21.53 | 63.37 ± 21.53 | 0.48 | 0.74 |
| AUC (ng/mL per 4 h) F | 41.52 ± 27.39 | 84.65 ± 29.26 | 48.51 ± 25.38 | 197.26 ± 26.74§c | 125.73 ± 26.74§cd | 106.99 ± 26.74d | 0.26 | 0.06 |
| Incline rate (ng/mL per min) H | 0.09 ± 0.02 | 0.09 ± 0.02 | 0.08 ± 0.02 | 0.06 ± 0.02 | 0.07 ± 0.02 | 0.07 ± 0.02 | 0.98 | 0.97 |
a,b: P = 0.02; c,d: P = 0.01
¥Control tended (P = 0.09) to have greater LH mean concentration than sunflower at wk2. §Control tended (P = 0.08) to have greaterAUC than canola at wk2. AWeek1: First week after calving (n = 5 cows per treatment); Week2: Second week after calving (n = 5 or 6 cows per treatment); BTrt: Dietary treatment; Cwk: Postpartum week; DPeak: The highest concentration of LH after GnRH administration; EPeak-time (min): The interval in minutes from GnRH administration to LH peak; FAUC: Area under curve = 1/2∑Xi-1 (Yi-1 + Yi), where Xi and Yi are sampling time and LH concentration (ng/ml), respectively; HIncline rate = (peak concentration– basal concentration)/Time (min)