# Colostrum Quality as an Indicator of the Immune Status of Cows and Its Association with Peripartum Disease Risk in a Grazing Dairy Herd

## TL;DR

High-quality colostrum from cows is linked to lower risk of peripartum diseases, suggesting it reflects the cow's immune status.

## Contribution

This study introduces colostrum quality as a novel indicator of cow immune status and its association with peripartum disease risk.

## Key findings

- Higher colostrum quality (Brix grades) was associated with lower risks of dystocia, stillbirth, and clinical endometritis.
- Colostrum quality was not related to retention of fetal membranes or metritis.
- Calving season influenced colostrum quality, but parity, dry period length, and previous milk yield did not.

## Abstract

The periparturient period is crucial for cows as they prepare to give birth and produce milk. This period is challenging because cows experience negative energy balance, hypocalcemia, oxidative stress, systemic inflammation, and a weakened immune response, leading them to an increased risk of peripartum diseases. Of all the above challenges, the one that has received the least attention from the scientific community is the immune status of cows. Colostrum quality evaluation is a common on-farm practice to measure the source of immunity for newborn calves. We believe that colostrum quality can also be an indicator of the immune status of the cows producing it. Therefore, we conducted a study to evaluate the association between colostrum quality, as a potential indicator of the immune status of the cows, and the risk of developing peripartum diseases in a herd of grazing dairy cows. We found that cows with higher colostrum quality had lower risks of diseases, such as stillborn, dystocia, and endometritis. Our findings suggest that colostrum quality evaluation could be a helpful tool not only for the potential transfer of immunity to calves but also for the indirect assessment of the immune status of cows.

This study aimed to evaluate the association between colostrum quality, as indicative of the immune status of the cows, and peripartum disease risk occurrence in a herd of grazing dairy cows. A prospective cohort study was conducted on a grazing dairy farm with 3000 Holstein milking cows from 15 March 2022 to 15 March 2023. Multivariable binary logistic models evaluated the association between colostrum quality (expressed in Brix grades as a continuous predictor) and the risk of peripartum diseases (including dystocia, stillbirth, retention of fetal membranes, metritis, and clinical endometritis). We found that colostrum quality was negatively associated with the risk of dystocia (p = 0.02), stillbirth (p < 0.01), clinical endometritis (p = 0.02), and total peripartum diseases (p < 0.01). Conversely, colostrum quality was not related to the risk of retention of the placenta (p = 0.25) or metritis (p = 0.76). Additionally, we found that the calving season affected colostrum quality (p < 0.01). Conversely, parity number, dry period length, and milk yield in previous lactation did not affect it (p > 0.10). We concluded that colostrum quality, expressed in Brix grades, is negatively associated with peripartum disease risk in dairy cows and could be a useful indicator of the immune status of the cow.