This book contains 19 chapters which covers from the sex ratio, body weights and growth rates, milk production traits during first to four lactations, part lactation records, test day records, persistency, reproduction traits, persistency and its genetic and phenotypic estimates, correction factors, extension of lactation records and prediction of lactation milk yield, selection index, lactation curve modeling and genetic evaluation of Sahiwal cows and sires using first and part lactation records.