Abstract

CASTILLO GALLEGOS, Epigmenio. Characterization of the lactation curve of f1 Holstein-Zebu cows. Ecosistemas y recur. agropecuarios [online]. 2018, vol.5, n.14, pp.335-343. ISSN 2007-901X.  https://doi.org/10.19136/era.a5nl4.1524.

The objective was to find a function to describe the lactation curve of grazing Holstein - Zebu cows (n=23) in tropical México. Twelve were based on the general nonlinear function A* ϕ 1(x)* ϕ 2(x): A, a positive scalar; ϕ 1, a positive monotonically increasing function with asymptote ϕ 1 = 1 ; ϕ 2, is a monotonically decreasing function with asymptote ϕ 2 = 0 and initial value of 1; and x is lactation time (days). For ϕ 1, the Mitscherlitsch, Michaelis-Menten, generalized saturation kinetics, logistic, Gompertz and hyperbolic tangent equations were used, whilst for ϕ 2, they were the exponential and inverse linear. A gamma function, the more used, and the addition of two logistic equations, the more biologically explicit, were also included. The smaller value of the Akaike information criterion corrected (AIC c ) indicated the latter was the one with the best fit, so its use to study factors affecting the lactation curve is suggested.

Keywords : Tropics; dual-purpose; grazing; milk yield; nonlinear functions.