Effects of Calving Body Condition Score on Blood Acid–Base Balance of Primiparous Holstein-Friesian Dairy Cows in a Commercial Dairy Farm: A Case Study

• Main Authors: Rodrigo Muiño, Joaquín Hernández, José L. Benedito, Cristina Castillo
• Format: Article
• Language: English
• Published: MDPI AG 2021-07-01
• Series: Animals
• Subjects: heifers; parturition; body condition score; nutrition; acid–base balance; milk yield
• Online Access: https://www.mdpi.com/2076-2615/11/7/2075

The study was carried out on 27 healthy primiparous Holstein heifers (620 ± 50 kg) kept in a commercial dairy herd. The animals were divided into two groups taking into account the body condition score (BCS) index: BCS < 3.5, <i>n</i> = 12; BCS > 3.5 <i>n</i> = 15. The study period started one month before calving (BC), and ran until one month after calving (AC). Venous blood samples were collected 1 month and 1 week BC, and 1 week and 1 month AC. This study had two objectives: (i) to assess whether a higher or lower BCS affected total milk production and its quality; (ii) to assess changes in the internal fluid (venous pH; partial pressure of CO₂, ppCO₂; bicarbonate; total CO₂, TCO₂; base excess, BE; electrolytes Na⁺, K⁺, Cl⁻; and anion gap, AG) that occur during this phase depending on the BCS. We can conclude that the BCS at calving does not affect the productive status during lactation, both in terms of the quantity and quality of milk produced. The excess of crude protein (CP) added through the ration in the lactation phase can trigger a tendency to an alkalotic state, in this case compensated by respiratory buffering mechanisms, as reflected by the TCO₂. The changes in electrolytes are a reflection of the movement of free water for milk production, where a balance between measurable anions and cations is observed.