Mastitis in beef cows and its effects on calf weight gain

Area of Science:

• Veterinary Medicine
• Animal Science
• Bovine Health

Background:

• Intramammary infection (IMI) is a significant concern in beef cattle production.
• Prevalence and impact of IMI on milk somatic cell counts (SCC) and calf performance are critical economic factors.
• Understanding pathogen dynamics throughout lactation is essential for effective management.

Purpose of the Study:

• To determine the prevalence of IMI, SCC, and associated calf weight gain effects in beef cows.
• To identify common mastitis pathogens and their prevalence across lactation stages.
• To evaluate the efficacy of intramammary antibiotic treatment post-weaning on subsequent infection rates.

Main Methods:

• Aseptic quarter milk sampling from 51 purebred and 69 crossbred beef cows at early, mid, and late lactation.
• Bacteriological culture for pathogen identification and SCC determination.
• Calf weight gain adjusted to 205 days and post-calving infection rates compared between treated and control groups.

Main Results:

• Quarter infection prevalence increased from 13.1% in early to 27.5% in late lactation; cow prevalence rose from 25.8% to 54.4%.
• Staphylococcus aureus and Corynebacterium bovis were frequently isolated; S. aureus-infected dams had significantly lower calf weight gain (-9.6 kg).
• Post-weaning intramammary treatment reduced subsequent calving infection prevalence (8.2% treated vs. 22.4% control) but did not affect new infection rates.

Conclusions:

• IMI prevalence escalates throughout lactation in beef cows, with notable impacts on calf growth, particularly from S. aureus.
• Intramammary treatment post-weaning is effective in clearing existing infections and reducing subsequent calving infection rates.
• Further research is needed to address new infection development during the dry period and early lactation.