Heart Girth as a Predictor of Body Weight in Lactating Cows

Area of Science:

• Animal Science
• Dairy Cattle Production
• Agricultural Engineering

Background:

• Body weight (BW) is crucial for dairy cow management but difficult to measure directly on a large scale.
• Heart girth (HG) offers a practical alternative for estimating BW, yet data for lactating cows, particularly local breeds, is scarce.

Purpose of the Study:

• To develop and validate equations for estimating BW from HG in lactating Holstein, Simmental, and Rendena dairy cows.
• To assess the influence of days in milk and parity on the accuracy of BW estimation from HG.

Main Methods:

• Collected BW and HG data from 293 lactating cows (Holstein, Simmental, Rendena) across 6 Italian farms with automatic milking systems.
• Utilized linear, quadratic, and cubic regression analyses to model BW based on HG, incorporating adjustments for days in milk and parity.
• Evaluated model performance using the coefficient of determination and root mean square error.

Main Results:

• Regression models adjusted for days in milk and parity demonstrated the best predictive performance for BW estimation from HG.
• The highest accuracy in BW prediction using HG was observed in Holstein and Simmental breeds.
• The study confirmed HG as a dependable indicator for BW in the studied lactating dairy cow breeds.

Conclusions:

• Heart girth (HG) provides a reliable and practical method for estimating body weight (BW) in lactating Holstein, Simmental, and Rendena cows.
• Incorporating adjustments for days in milk and parity significantly enhances the accuracy of HG-based BW estimation equations.
• These findings support the use of HG measurements for routine BW monitoring in dairy herds, facilitating better herd management.