Abstract The objective of this study was to determine the influence of environmental factors on milk yield in mestizo goats. Analyses of variance was performed for milk yield for test-day in the last third of lactation. The information for this study was taken from the goat production system of the Universidad Francisco de Paula Santander, Seccional Ocaña. The productive system has 90 animals, of which 840 samples of milk belonging to 20 goats were analyzed. Milk yield averages for 5 th months lactation and 6 th months lactation were 1.29±0.85 kg and 0.95±0.55 kg, with coefficients of variation from 29.11% to 39.46%, respectively. The initial results with the available information suggest that the non-genetic effects of birth month and year (and their interactions) were highly significant. While, the covariable age (linear effect) was not significant in any milk yield for test-day and the quadratic effect was highly significant and significant for fifth and sixth month of lactation, respectively. Consequently, it can be suggested that test-day milk yield in mestizo goats of Ocaña’s region is influenced by non-genetic factors such as the month, year and age of the female at kidding.