Functional relations between calving percentage (y) and total previous year’s rainfall (TPYR, x) were estimated using data from three private cattle ranches in the Potosino-Zacatecano highlands. TPYR data were obtained from the two official weather stations nearest to each ranch and with the same climate type. Using these relations, the calving percentage that occurred in 2015 (a year not included in the estimation of these relations) was predicted and statistically collated for the Laguna Seca (LS), San José (SJ) and El Porvenir (EP) ranches. Estimated correlations between calving percentage and rainfall were positive and significant for each ranch. Simple linear regression models were: y=26.2800 + 0.0629 (x) for LS; y=30.2438 + 0.0973 (x) for SJ; and y=23.6172 + 0.0808 (x) for EP. The variation in the calving percentage explained by TPYR was 59.2 % for LS, 62.0 % for SJ and 84.9 % for EP. Calving percentages recorded during 2015 for EP and LS (72.2 and 64.0 %, respectively) were greater than the 95 % confidence intervals, due to various recent improvements in herd reproduction; on the other hand, the calving percentage recorded during 2015 for SJ did fall within this range.