Mastitis in Heifers: Prevalence, Strategy for Control during the Periparturient Period, and Economic Implications

Intramammary infections in breeding age and pregnant heifers are much higher than previously thought. Many of these infections can persist for long periods of time, are associated with elevated somatic cell counts, and likely impair mammary development during gestation and affect milk production after calving. Prepartum intramammary antibiotic infusion of heifer mammary glands a few weeks before calving is an effective procedure for eliminating many infections in heifers during late gestation and for reducing the prevalence of mastitis in heifers both during early lactation and throughout lactation. Prepartum antibiotic-treated heifers produced significantly more milk and had significantly lower somatic cell count scores than untreated control heifers. These observations are likely associated with or due to the lower prevalence of mastitis pathogen isolation in prepartum antibiotic-treated heifers throughout lactation. Prepartum antibiotic treatment to reduce the rate of mastitis in heifers during early lactation was economically beneficial. Prepartum antibiotic-treated heifers produced 531 kg more milk than the untreated control group. Multiplying this increase by a milk price of $0.348/kg yielded a $184.54 (£122) per-heifer increase in gross revenue. Subtracting the cost of treatment from gross revenue (including the cost of testing for antibiotic residues), the net revenue from the actual production increase amounted to $174.92 (£115) per heifer.