Comprehensive Study of Sperm Proteins and Metabolites Potentially Associated with Higher Fertility of Zebu Cattle (<i>Bos indicus</i>) in Tropical Areas

Crossbreeding of zebu cattle (<i>Bos indicus</i>) with European breeds (<i>Bos taurus</i>) producing crossbred cattle was performed to overcome the low growth rates and milk production of indigenous tropical cattle breeds. However, zebu cattle fertility is higher than those of crossbred cattle and European breeds under warm conditions. Combination study of proteomics and metabolomics toward Malaysian indigenous breed Kedah × Kelantan-KK (<i>B. indicus</i>) and crossbreed Mafriwal-M (<i>B. taurus</i> × <i>B. indicus</i>) to understand physiological reasons for higher thermotolerance and fertility in Zebu cattle sperm. 161 regulated metabolites and 96 regulated proteins in KK and M (<i>p</i> < 0.05) showed more efficient carbohydrate and energy metabolism, higher integrity of the DNA and plasma membrane, a lower level of reactive oxygen species, and higher levels of phospholipids, which confirmed higher sperm plasma membrane integrity in KK. A stronger antioxidant system and lower polyunsaturated fatty acids help KK sperm cope with oxidative stress under warm conditions. The higher abundance of flagella structural proteins in KK provides a stronger structure that supports sperm motility. Abnormality of flagella, plasma membrane disruption, and DNA fragmentation were higher in M. These findings provide selective molecular markers for developing high-producing and more thermotolerant cattle breeds in tropical areas (197 words).