Analysis of lactation curves in crossbred Anglo-nubian goats
1999
Banjong Jongrakwattana | Sirapong Siriraksa | Chatchaval Viriyasombat(Department of Livestock Development, Bangkok (Thailand). Thepa Livestock Breeding Station)
Study utilized lactation curve as a model for lactation characteristic of 30 lactations, parity 1-4, from 22 crossbred Anglo-Nubian goats. Milk production from each goat (kg/day) were taken at weekly interval from day 6 to day 168 after kidding. Data were fitted by nonlinear estimation to the mathematical equation, incomplete gamma function, Y sub(n)= an sup(b)e sup(-cn). Estimated coefficients were a=0.97+-0.99, b=0.26+-0.28 and c=0.009+-0.007. Estimated functions composed of peak yield (1.40+-0.45 kg), time of peak yield (41.70+-29.30 days) and 150-days yield (169.20+-63.16 kg). The coefficients were significantly correlated (p LT 0.05) in the opposite direction for a b and a c, in the same direction for b c. Peak yield and 150-days yield were significantly correlated in the same direction (p LT 0.05). No correlation was found for the other estimated functions. Using 150-days yield as an estimated function is more appropriated than traditional 305-days yield because goats in Thailand are non seasonal breeder. Results from this study suggested that the lactation model can be used to determine various factors affecting lactational characteristics in Anglo-Nubian crossbred goats. Consequently, it will be one of the tools used to select and improve dairy goat breeds.
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