# Influence of maternal or neonatal Vitamin A injection on calf performance and muscle transcriptomics in the cow-calf phase

## TL;DR

Injecting vitamin A during late pregnancy or early life improves male calf growth and muscle gene activity.

## Contribution

Maternal vitamin A injection had a stronger impact on muscle gene expression in male calves compared to postnatal injections.

## Key findings

- Male calves from vitamin A-injected mothers had higher average daily gain and weaning weight.
- Maternal vitamin A injection increased expression of genes like RARA, MYF5, and PAX7 in male calves.
- Gene expression differences were more pronounced in males than females.

## Abstract

This study investigated the effects of vitamin A (VA) injection on growth performance, muscle development, and skeletal muscle transcriptomics in calves during the cow-calf phase. Pregnant cows at 250 days of gestation were randomly assigned to one of three treatments: control (CON; no VA injection), VA injection in cows at 250 d of gestation (VAcow), or VA injections in calves at birth and 60 days of age (VAcalf). Calves were weighed at 60 d and weaning. Carcass ultrasound and muscle biopsy were conducted at weaning. Gene expressions were analyzed by RT-qPCR. Male calves in the VAcow group had higher (P = 0.01) ADG than Control males and VA-treated females. Weaning BW was greater (P < 0.01) in VAcalf and VAcow males compared to Control males and VA-treated females. Gene expression analysis revealed that RARA, MYF5, CEBPA, and DLK1 were higher (P ≤ 0.05) expressed in Control and VAcow calves than in VAcalf calves. Expressions of ZNF423 and RXRA tended to be greater (P ≤ 0.09) in VAcow males than in VAcalf males and VA-treated females. The expression of PAX7 was higher (P < 0.01) in VAcow males than in all other groups. Also, IGFR1 expression tended to be greater (P = 0.07) in VAcow males than in Control and VAcalf males and VAcalf females. In conclusion, VA injection during late gestation or early postnatal life improved growth of male calves. Maternal VA injection had a more pronounced effect on muscle gene expression, particularly in male calves.