Comparative Response of Milk pH, Electrical Conductivity and Infrared Thermography across an Increasing Somatic Cell Count Gradient in Early-Lactation Alpine × Beetal Crossbred Does
Animesh Patel
Division of Animal Physiology, ICAR-National Dairy Research Institute, Karnal, Haryana 132001, India.
Bagavathi Muthappan
Division of Animal Physiology, ICAR-National Dairy Research Institute, Karnal, Haryana 132001, India.
Manisha Choudhary
Division of Animal Physiology, ICAR-National Dairy Research Institute, Karnal, Haryana 132001, India.
Ajay Kumar Dang *
Division of Animal Physiology, ICAR-National Dairy Research Institute, Karnal, Haryana 132001, India.
*Author to whom correspondence should be addressed.
Abstract
Background: Somatic cell count (SCC) in goat milk is influenced by both udder health and physiological factors, which limits its interpretation as a sole screening measure.
Aims: This study compared milk pH, electrical conductivity (EC), and three region-specific udder surface temperatures across a graded SCC scale in clinically healthy early-lactation Alpine × Beetal crossbred does and identified the lowest SCC class at which each indicator differed from the reference.
Study Design: Cross-sectional, six SCC strata.
Place and Duration of Study: Livestock Research Centre and Division of Animal Physiology, ICAR-National Dairy Research Institute, Karnal, Haryana, India.
Methodology: Forty-eight clinically healthy, multiparous, early-lactation Alpine × Beetal crossbred does were sampled on three consecutive days. Daily values were averaged per doe, and does were allocated according to their three-day mean SCC (<4 to >12 × 10⁵ cells/mL; n = 8 per group). Milk pH and EC were measured using a Lactoscan MCC Combo; teat apex (TAT), teat skin surface (TSST) and udder skin surface (USST) temperatures were measured by infrared thermography. Data were analysed by one-way ANOVA with Tukey’s HSD and Pearson correlation, with the doe as the experimental unit.
Results: Milk pH rose 9.84% (6.30 to 6.92), first differing from the reference at 8–10 × 10⁵ cells/mL (P < .05). EC rose 24.72% (5.46 to 6.81 mS/cm) but, varying widely between animals, separated only at 10–12 × 10⁵. TSST rose 2.65 °C, separating at 8–10 × 10⁵; TAT rose 1.53 °C, separating at 10–12 × 10⁵; USST rose by 2.38 °C, but no group differed significantly from the reference. SCC correlated with EC (r = 0.906), pH (r = 0.898), TSST (r = 0.894), TAT (r = 0.741) and USST (r = 0.400).
Conclusion: Milk pH and TSST responded earliest, at 8–10 × 10⁵ cells/mL, followed by TAT and EC at 10–12 × 10⁵; USST did not respond detectably. Milk pH offers the best combination of sensitivity, cost and speed. The closer tracking of SCC by TSST than by USST is contrary to earlier reports and requires replication with ambient conditions recorded.
Keywords: Alpine × Beetal crossbred does, early lactation, somatic cell count, milk pH, electrical conductivity, infrared thermography, teat apex temperature, teat skin surface temperature, udder skin surface temperature, udder health