ISSN : 1225-2964(Print)
ISSN : 2287-3317(Online)
ISSN : 2287-3317(Online)
Annals of Animal Resource Sciences Vol.26 No.1 pp.13-20
DOI : https://doi.org/10.12718/AARS.2015.26.1.13
DOI : https://doi.org/10.12718/AARS.2015.26.1.13
Effect of Age at the First Pregnancy on Calving Status in Holstein Heifers
06 Novermber 2014
08 June 2015
08 June 2015
Abstract
Raising replacement heifers is important aspect of dairy farm management that can be characterized as a
long-term performance and high-cost production period. This study was investigated the effect of month of
age at the first pregnancy on calving difficulty of Holstein heifers. Heifers was inseminated with semen of
easy-calving sire and the reproductive performance was compared for the effect of first pregnancy at 12-14
months of age (12 month old), 15-16 months of age (15 month old), 17-19 months of age (17 month old) and
> 20 months of age (20 month old) in Holstein heifers. Holstein heifers showed different easy calving score
(ECS) depending on their ages; frequency of ECS 1 was 55.2%, 64.9%, 59.4% and 52.0% at 12, 15, 17 and 20 month of age, respectively. Frequency of ECS 4 was 5.2%, 1.8%, 6.3% and 4.8% at 12, 15, 17 and 20 month of age, respectively. The rates of retained placenta postparturition in first pregnancy age category was 12.3% at 12 months of age, 5.3% at 15 months of age, 9.4% at 17 months of age and 19.0% at 20 months of age. When It was evaluated by present results, the reproductive performance like easy calving score (ECS), retained placenta rates, and abortion and stillbirth rates of heifers which was inseminated at 14 months old or less and at 17 months old or more was reduced. Therefore, the first pregnancy age for optimum reproductive performance was 15-16 months.
long-term performance and high-cost production period. This study was investigated the effect of month of
age at the first pregnancy on calving difficulty of Holstein heifers. Heifers was inseminated with semen of
easy-calving sire and the reproductive performance was compared for the effect of first pregnancy at 12-14
months of age (12 month old), 15-16 months of age (15 month old), 17-19 months of age (17 month old) and
> 20 months of age (20 month old) in Holstein heifers. Holstein heifers showed different easy calving score
(ECS) depending on their ages; frequency of ECS 1 was 55.2%, 64.9%, 59.4% and 52.0% at 12, 15, 17 and 20 month of age, respectively. Frequency of ECS 4 was 5.2%, 1.8%, 6.3% and 4.8% at 12, 15, 17 and 20 month of age, respectively. The rates of retained placenta postparturition in first pregnancy age category was 12.3% at 12 months of age, 5.3% at 15 months of age, 9.4% at 17 months of age and 19.0% at 20 months of age. When It was evaluated by present results, the reproductive performance like easy calving score (ECS), retained placenta rates, and abortion and stillbirth rates of heifers which was inseminated at 14 months old or less and at 17 months old or more was reduced. Therefore, the first pregnancy age for optimum reproductive performance was 15-16 months.