Annual Research & Review in Biology

Ongole cattle are an indigenous Bos indicus breed characterised by a light or white adult coat, whereas some calves are born with dark brown or reddish-brown pigmentation. This observational study documented early coat colour transformation in Ongole calves maintained at the Livestock Research Station, Lam, Guntur, Andhra Pradesh, India. Eighteen calves with dark brown or reddish-brown coats at birth were followed for 12 weeks from March to May 2025 under standard farm management conditions. Coat colour changes were assessed by repeated visual observation and photographic documentation under natural daylight. A progressive reduction in dark pigmentation was observed during the study period. Calves showed visible coat lightening during the early weeks, followed by the development of cream to off-white areas by 12 weeks of age. The progression was not uniform over time and was more evident during the later observations. These findings indicate a consistent developmental coat colour change in the calves examined and provide a phenotypic baseline for subsequent investigation. Because assessment relied on visual and photographic observations without instrumental colour measurement, biochemical pigment analysis, genotyping, or controlled environmental comparison, the study does not establish the mechanisms responsible for the observed transition. Further work using objective colourimetry, larger longitudinal samples, and integrated genetic and environmental measurements is required to clarify the basis and functional relevance of coat colour transformation in Ongole calves.