RELATIONSHIP BETWEEN SPERM TAIL MITOCHONDRIAL SHEATH LENGTH, FERTILITY AND PRODUCTIVE CHARACTERISTICS IN BULLS USED IN ARTIFICIAL INSEMINATION

Abstract

From the reproductive point of view, male fertility interferes directly and indirectly in the expression of zootechnical indices and must be easily measured and directly applied in herds. The length of the sperm intermediate piece (IP), occupied by the mitochondrial sheath (MS), is responsible for the production of sperm energy, as this is where there is the highest concentration of mitochondria. This work aims to identify the relationship between the mitochondrial sheath as a fertility marker and productive characteristics of Nellore bulls used in FTAI. The intermediate pieces of 100 sperm were measured for each semen sample, from 30 Nellore bulls, evaluated by the Geneplus-Embrapa program. In addition to the IP measurements, the seminal parameters of the samples after thawing were analyzed. TRT motility (slow heat resistance test) showed a significant correlation with TRT vigor. The midpiece showed a significant correlation (P<0.05) with the EPDs of: age at first calving (AFC); scrotal circumference (SP); heritability of stay (stayability %); birth weight (BW) and residual food intake (RFI). Thus, the intermediate piece (IP) showed positive correlations with sperm quality, and with the EPD data (expected differences in progeny) related to the productive characteristics of Nelore bulls.