Strand 2.6 — Population Management in Animal Science: Reproduction, Selection, and Parturition

Reproductive maturity

The point at which an animal's reproductive system is developed enough to conceive or breed without unacceptable health risks.

Physiological capability

Includes hormones, functional reproductive organs, and viable gametes necessary for reproduction.

Breeding too early

Can stunt growth, increase difficulties in birth, reduce productivity, and increase culling.

Breeding too late

Can waste resources and delay genetic progress.

Genetics in reproductive maturity

Sets the potential timeline for when animals reach reproductive readiness.

Body weight as a driver of puberty

Puberty is more closely linked to reaching target body weight than to age.

Nutrition importance

Affects onset of puberty, regularity of cycles, ovulation rate, and semen quality in males.

Photoperiod influence on reproductive cycles

Day length affects breeding behaviors, mediated by hormones like melatonin.

Health status impacts reproduction

Disease and parasites can delay puberty and reduce conception rates.

Social environment effects on reproduction

Stress and social factors can influence timely reproductive signaling.

Selection for reproductive readiness in females

Includes assessing cycling, pregnancy maintenance, safe delivery, and maternal success.

Indicators of female readiness

Adequate growth, normal reproductive anatomy, evidence of estrus, and soundness.

Selection for reproductive readiness in males

Focus on breeding soundness, reproductive anatomy, semen quality, and libido.

Breeding values (BV)

The genetic merit of an individual for a trait that is predictably passed to offspring.

Heritability (h²)

Proportion of trait variation in a population due to additive genetic variation.

Expected progeny difference (EPD)

Half the breeding value indicating expected genetic advantage in offspring.

Response to selection (R)

Expected change in population mean due to selection based on heritability and selection differential.

Selection differential (S)

The difference between selected parents' mean phenotype and the original population mean.

Population management goal

Produce animals that fit specific goals such as growth or fertility.

Dystocia

Difficult birth that can occur due to problems with the dam, fetus, or the birthing process.

Signs of normal parturition

Restlessness, seeking isolation, udder filling, and cervical changes are typical preparation signs.

Stages of labor

Consists of cervical dilation, delivery of the offspring, and expulsion of the placenta.

Abnormal presentations during parturition

Malpositions that complicate birth, requiring careful assessment.

Retained fetal membranes risks

Increases likelihood of infection and delays return to fertility.

Immediate care after birth

Ensure newborn breathing, warmth, and confirm colostrum intake for immunity.

Postpartum monitoring importance

Watch for uterine complications and ensure the dam’s recovery and health.

Common misconception in parturition

Any assistance can be detrimental; timely and proper intervention is necessary.