PREDICTION OF MILK PRODUCTION BY LACTATION OF COWS IN THE MEXICAN TROPICS

Abstract

Objective: to evaluate non-linear and linear mathematical models to estimate milk production per lactation at different frequencies of milk weighing from Holstein (Ho), Brown Swiss (SP) cows and their crosses with Zebu (C). Design/methodology/approach: Models evaluated: Wood, Wilmink and Linear Interpolation. Daily milk production records of 471 lactations from 72 cows were used; 1,884 records were created with weekly, biweekly and monthly milk production frequencies. There were included in the statistical model the genotype (HoxC and SPxC), calving season (rain and dry), and number of lactations (1 and 2) with double and triple interactions. The statistical analyses were carried out with GLM from MINITAB v17. Means were compared with Tukey's test.

Results: no differences were found (P? 0.05) between models for average milk production per lactation in kg, obtained from daily measurements or estimated from weekly, biweekly, and monthly data, but for calving time, number of lactations, and genotype factors showed differences (P?0.05) in milk production per lactation.

Study limitations/implications: Daily milk production records are necessary to obtain lactation productions, applied models predict milk production in a similar way in different weighing frequencies in Holstein, Swiss Brown cows and their crosses with Zebu.

Findings/conclusions: the models used predict milk production per cow in a similar way at different weighing frequencies.