PRE- AND POST-NATAL DEATH OF LIVESTOCK RESULTING FROM ACTION OF LETHAL GENES – A REVIEW

Abstract

There is a great concern to examine the loss of livestock through pre- and post-natal death as well as anomalies that interfere with growth and production. One of the causes of these losses is the effect of lethal genes. Lethal genes and their effects on the performance of livestock species were reviewed in this work. Most of these anomalies were found to be controlled by single recessive genes while only a few recognized to be geared by single dominants. Physical identification of the heterozygote is difficult in the flock except in a few cases. What worsens the situation is some environmental factors that were found to produce phenotypes similar to genetic deformity described. However, genetic testing can confirm the actual state of the case. Elimination of lethal genes depends on the type of genes present; heterozygote can be diagnosed by blood typing or enzymes estimating, X-rays of neonates can also facilitate early diagnoses in defects where skeletal abnormality is present and a few conditions such as imperforated anus, surgical operation is the remedy. Although, several defects do not have genetic test, with advancement in molecular technology, genetic defects in farm animals can be effectively managed as DNA samples can be taken from an afflicted animal for diagnosis.