British Cattle Veterinary Association

Minimal losses, optimal growth rates and excellent fertility management are key factors of a good dairy heifer rearing system. This study determined the mortality, growth and fertility of Holstein-Friesian heifers on 19 UK dairy farms, and examined the relationships between growth parameters and concentrations of insulin-like growth factor-I (IGF-I), with each of these 3 key areas. A cohort of 506 heifer calves was recruited at 1 month and monitored through to first calving. Size parameters (body weight, heart girth, height at withers and crownrump length) and concentrations of IGF-I were measured in each calf at approximately 1 and 6 months, and the average daily change in each size parameter was calculated. On average 8% of male and female calves were born dead, or died within 24 hours of life, and approximately 15% of heifer calves born alive failed to reach first calving