Genetic parameter estimates for prenatal and postnatal mortality in Nellore cattle

Area of Science:

• Animal Genetics
• Livestock Production
• Quantitative Genetics

Background:

• Prenatal (PRE) and postnatal (POS) mortality are critical issues in Nellore cattle production.
• Understanding genetic parameters is essential for developing effective breeding strategies to reduce calf losses.

Purpose of the Study:

• To estimate genetic parameters for PRE and POS mortality in Nellore cattle.
• To investigate the influence of direct and maternal genetic effects on calf mortality.
• To assess the potential for genetic selection to mitigate calf mortality rates.

Main Methods:

• Analysis of 13,141 PRE and 17,818 POS records from Nellore females.
• Utilized a sire-maternal grandsire threshold model with Bayesian inference.
• Incorporated contemporary groups, dam age, and birthweight as effects.

Main Results:

• PRE and POS rates were 3.00% and 4.04%, respectively.
• Low direct and maternal heritability estimates were found for both PRE (0.07, 0.17) and POS (0.02, 0.07).
• Maternal genetic effects showed a stronger influence on preweaning mortality than direct genetic effects.

Conclusions:

• Both PRE and POS exhibit low genetic variability, suggesting significant environmental impacts.
• The maternal genetic component is a key factor in calf mortality, more so than the direct genetic component.
• Effective genetic reduction of calf mortality requires progeny testing with a large number of offspring per sire.