"Estrus Synchronization and Periconceptual Supplementation Affect the" by D. M. Larson, R. D. Richardson et al.

Agricultural Research Division of IANR

 

Date of this Version

2010

Citation

The Professional Animal Scientist 26 ( 2010 ):527–533

Comments

Copyright 2010 American Registry of Professional Animal Scientists

Abstract

Experiments evaluated estrus synchronization and periconceptual supplementation on pregnancy rate and calf production. Approximately one-half of heifers in 2 pastures (yr 1) or 4 pastures (yr 2) were injected with prostaglandin F (PGF; n = 1,182) or not (NPGF; n = 1,208) 5 d after fertile bulls were introduced for 25 d. In yr 2, a total of 1,230 heifers were randomly assigned to 1 of 4 pastures; 2 received a supplement providing 100 g/d of Ca propionate (1.4 kg/d, 20% CP) 2 d before through 19 d after bull exposure and 2 did not in a 25-d breeding season.

Pregnancy rate was reduced (P < 0.01) in the PGF-synchronized heifers relative to the NPGF heifers (73.7 vs. 78.3% for PGF and NPGF, respectively. Approximately 10% more (P < 0.01) PGF-synchronized heifers that became pregnant calved in the first 21 d. Subsequently, weaning weight and the value of steer calves from PGF dams tended to be greater (P < 0.10) than those of steer calves from NPGF dams. Supplemented heifers were heavier (P < 0.05) at pregnancy diagnosis; however, pregnancy rate was unaffected (P > 0.10). Calf birth weight was greater (P < 0.05) for calves from dams receiving the Ca propionate supplement, but weaning weight and calf value were similar (P > 0.10). In this study, injection of PGF in a 25-d breeding season improved synchrony of calving and increased steer calf weaning weight and value; however, supplemental nutrition during the periconceptual period was of limited value.

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