Table 2.
Description of three parity groups of cows in Genesis herdsa
| Variable | Parity | ||
|---|---|---|---|
| 1 | 2 | >2 | |
| Body weight at calving, kg | 440 | 506 | 550e |
| Average daily gainb, kg | 0.13 | 0.10 | |
| Calf birth weight, kg | 39 | 41 | 42 |
| Calving interval, days | 488 | 427 | 427 |
| Average daily milk yield,c,d kg | |||
| Early lactation (90 days) | 8.5 | 9.0 | 10.0 |
| Mid lactation (90 days) | 7.0 | 8.0 | 8.5 |
| Late lactation (90 days) | 5.0 | 5.5 | 6.0 |
| Early dry (128 daysf) | 0.0 | 0.0 | 0.0 |
| (67 daysg) | 0.0 | 0.0 | 0.0 |
| Late dry (90 daysh) | 0.0 | 0.0 | 0.0 |
| Body weighti (and body conditionj) | |||
| Early rainy season (Jun 1–July 31) | 426 (2.75) | 506 (3.00) | 550 (3.00) |
| Late rainy season (Aug 1–Sep 30) | 440 (3.00) | 506 (3.00) | 550 (3.00) |
| Early dry season (Oct 1–Dec 31) | 426 (2.75) | 469 (2.75) | 550 (3.00) |
| Late dry season (Jan 1–May 31) | 410 (2.50) | 470 (2.50) | 532 (2.75) |
aThe primary breed group is ¾ Brown Swiss × ¼ Brahman
bAverage growth rate to reach target weights at subsequent calving
cAverage daily milk yields correspond to the mid-points of each physiological stage of lactation (45, 135, 225 days post-partum). These means correspond to 270-day lactation yields of 1,850, 2,000 and 2,200 kg for these parity groups, consistent with the overall herd average milk yield reported by Genesis members
dExpected average composition of milk in coastal Veracruz herds: milk fat = 3.4%, true protein = 3.1%, lactose = 4.7% (Cervantes-Acosta et al. 2005)
eMature weight is 550 kg with a body condition score of 3.0 units (5-point scale)
fAverage calving interval for primiparous cows calving in all forage seasons (16 months)
gAverage calving interval for second parity and mature cows calving in all forage seasons (14 months)
hThe 90-day period preceding parturition (late gestation)
iMature BW is 550 kg with BCS = 3.0. A 440-kg primiparous cow and a 506-kg second parity cow have a BCS 3.0. Maximum BW loss is 20% of calving weight for primiparous cows and for others when BCS <3.0. For parities ≥2 and BCS ≥3.0, maximum BW loss is 25% of mature weight
jThe BCS at calving were the consensus judgments of a panel of Mexican professionals. Using these reference scores for the season of early rains other BCS were predicted based on expected tissue dynamics and energy balances based on Fox et al. (2004)