REPRODUCTIVE PERFORMANCE OF BROWN SWISS AND MESTIZO BOVINE IN HUMID TROPIC

The ability of ruminants to regulate body temperature depends on the genotype. Dairy breeds are generally more sensitive to heat stress than beef breeds. Higher-producing animals are more susceptible to heat stress because they generate more metabolic heat. The objective of evaluating reproductive performance as a response of adaptability to the management and climatic conditions of the Humid Tropics. 78 animals were used (40 Brown Swiss, from Puno and 38 Mestizas from local origin) raised in humid tropic conditions. Parametric statistics are presented as analysis of measures of central tendency and dispersion, non-parametric statistics by frequency analysis, the χ2 test of independence was used to detect differences, α = 0.05. The categorized and continuous dependent variables were evaluated with Student's t test using SPSS Software v.23. The mean age at first estrus in Brown Swiss was 12.43 months, in mestizo cattle 18.68 months (P <0.05). Average age of first calving in Brown Swiss of 25.25 months versus mestizo cattle 28.34 months (P <0.05). Interval from calving to the first service in Brown Swiss was 99.29 days. Open days observed in Brown Swiss was 107.29 days. The pregnancy rate at the first service in Brown Swiss was 70.0% pregnancy at the first service and 30.0% at the second service, for the mestizo genotype it was 68.4% at the first service, 28.9 at the second and 2.6 at the third service (P> 0.05; X2 = 0.50; p = 0.47). It is concluded that bovine animals of the Brown Swiss genotype have a good reproductive performance in the Humid Tropic climate compared to the Mestizo genotype