# Monitoring changes in body reserves in gestating dairy heifers with 3-dimensional imaging technology: A potential tool to prevent early culling?

## TL;DR

3D imaging technology can better track body condition changes in pregnant dairy heifers, potentially helping to prevent early culling.

## Contribution

3D imaging enables more frequent and accurate monitoring of body reserves in gestating heifers compared to manual methods.

## Key findings

- 3D imaging detected small changes in body condition scores more efficiently than manual scoring.
- Body weight increased while body condition scores slightly decreased during gestation.
- Technicians' manual scores were generally higher than 3D imaging estimates.

## Abstract

Summary: Inadequate body reserves in dairy heifers can be associated with calving problems and, ultimately, premature culling. Body reserves are usually estimated by human evaluators (manual scoring), but frequent measurements are difficult to carry out due to the time required. Fine changes, especially in growing animals, such as heifers, are also hard to detect. The use of depth cameras, with frequent and repeated measurements and relevant analyses, can then be of interest. A comparison between manual (once a month) and automatic scoring (once a week) methods was performed on 13 Holstein heifers (from 3 months of gestation until 1 to 3 months of lactation). Results indicated that the use of depth cameras, with frequent and repeated measurements, makes it possible to more efficiently estimate the evolution of body reserves. Ultimately, this should allow for better monitoring of these animals' diet and body weights to limit the premature culling of dairy heifers.

Summary: Inadequate body reserves in dairy heifers can be associated with calving problems and, ultimately, premature culling. Body reserves are usually estimated by human evaluators (manual scoring), but frequent measurements are difficult to carry out due to the time required. Fine changes, especially in growing animals, such as heifers, are also hard to detect. The use of depth cameras, with frequent and repeated measurements and relevant analyses, can then be of interest. A comparison between manual (once a month) and automatic scoring (once a week) methods was performed on 13 Holstein heifers (from 3 months of gestation until 1 to 3 months of lactation). Results indicated that the use of depth cameras, with frequent and repeated measurements, makes it possible to more efficiently estimate the evolution of body reserves. Ultimately, this should allow for better monitoring of these animals' diet and body weights to limit the premature culling of dairy heifers.

•The use of depth cameras is of increasing interest in managing dairy production.•Fine changes in the body reserves of gestating heifers are more efficiently detected.•This detection could be of interest to prevent early culling in primiparous cows.

The use of depth cameras is of increasing interest in managing dairy production.

Fine changes in the body reserves of gestating heifers are more efficiently detected.

This detection could be of interest to prevent early culling in primiparous cows.

The use of 3-dimensional (3D) imaging technology to monitor dairy cows enables the acquisition of morphological, surface, and volume data, which can then be employed to estimate BW or BCS. Accurate tracking of morphological changes in these animals could lead to better management of the gestation and parturition periods, which are especially critical for primiparous cows. Indeed, BCS values that are too low or too high are associated with reproductive disorders and early culling after calving. To assess the potential utility of precise and continuous recordings in gestating animals, we studied BW and morphological changes in 13 gestating Holstein heifers from 3 mo of gestation until the start of lactation. Body condition score was estimated using both 3D imaging technology (BCS3d) and manual scores determined by trained technicians (BCSm). From mid-April (start of experiment) until the end of August (start of calving season) in 2021, average BW increased from 515 (±SD, 40.5) kg to 604 (±49.4) kg, whereas average BCS3d decreased slightly, from 2.50 (±0.19) to 2.32 (±0.30). A similar decrease was noted for BCSm, from 2.63 (±0.19) to 2.11 (±0.24). Linear regression between the 2 estimates of BCS indicated that the technicians usually gave a higher BCS value than the imaging device (BCS3d = 0.97 × BCSm; R2 = 0.58). Because of the small number of observations and the fact that the experiment ended after the first calving, we are not able to draw any conclusions about the long-term effects of changes in BCS during gestation on the overall longevity of cows. Nevertheless, using our system, it was possible to detect small changes in BCS during the first gestation of nulliparous cows. Such information could be employed to adapt the diet of heifers to avoid inadequate, insufficient, or excessive fatness at parturition, thus potentially ameliorating calving difficulties (dystocia) and poor starts to lactation. The precise evolution of BCS in the pregnant heifer is of great interest, and the next step will be to examine larger groups of animals to shed more light on the potential value of this technology.