Small for Gestational Age Calves: Part II-Reduced Fertility, Productive Performance, and Survival in Holstein Friesian Heifers Born Small for Their Gestational Age.

Recently: more attention has been given to low-birth-weight calves, often without considering gestation length. Calves can be classified as small for gestational age (SGA) when their birth weight is below the 10th percentile, similar to the definition in human medicine. While SGA babies face various health risks, it remains unclear if SGA calves face similar long-term health consequences.

Small for Gestational Age Calves: Part I-Concept and Definition, Contributing Prenatal Factors and Neonatal Body Morphometrics in Holstein Friesian Calves.

Low birth weight (BW) calves exhibit higher mortality rates, reduced body weights at parturition, lower first-lactation milk yields, and longer parturition to first insemination intervals. In human medicine, small for gestational age (SGA) births are associated with increased perinatal morbidity and long-term metabolic risks. This study aimed to define SGA in Holstein Friesian (HF) calves, evaluate their body measurements and proportions, and identify its prenatal risk factors.

The importance of developmental programming in the dairy industry.

The concept of developmental programming suggests that environmental influences during pre- and early postnatal life that can have long-term effects on future health and performance. In dairy cattle, maternal body growth, age, parity and milk yield, as well as environmental factors during gestation, have the potential to create a suboptimal environment for the developing fetus. As a result, the calf's phenotype may undergo adaptations.

The anogenital ratio as an indicator of reproductive performance in dairy heifers.

The anogenital distance (AGD) is considered a marker for prenatal androgen exposure and fertility in multiple species including humans. In dairy cattle, it is described as the length between the center of the anus and the clitoral base (AGDc). However, in other species, the distance from the center of the anus to the dorsal commissure of the vulva (AGDv) is also considered to be a predictor for fertility traits, as well as the anogenital ratio (AGR, defined as [AGDv/AGDc]*100).