A retrospective evaluation on the effects of a Bacillus-based probiotic supplementation on milk yield, milk composition, health status, and reproductive performance of dairy cows in Argentina.

Authors

Elias Giugge, Fernando M Clemente, Melina Briosso, Oscar C M Queiroz, Jens N Joergensen, Bruno I Cappellozza

Published in

Translational animal science. Volume 10. Pages txag144. Epub Sep 21, 2026.

Abstract

The objective of this retrospective before-and-after trial was to evaluate the effects of a Bacillus-based direct-fed microbial (DFM) on milk yield, composition, reproductive performance, and health status of dairy cows in a single commercial dairy farm in Argentina. The dataset used in the current study comprised January 2019 until September 2025, including roughly 1,300 to 1,600 lactating Holstein cows across the study period, split into 10 pens. The data between January 2019 to September 2023 was considered as the period pre-DFM feeding (57 mo; PRE), whereas the period of DFM supplementation (B. licheniformis 809 and B. subtilis 810) considered in the analysis ranged from October 2023 to September 2025 (24 mo; POST). During this period, the Bacillus-based DFM was fed at 3 g/cow per day. Milk yield was evaluated daily and individually for all lactating cows, while milk composition was evaluated monthly for the whole-farm. Based on these results, 4% FCM and ECM yield were determined. Moreover, reproductive and health data were also collected. All data were analyzed with the GLIMMIX and GLM procedure of SAS, considering pen as the experimental unit. No treatment × season interactions were observed for any of the productive and health variables (P ≥ 0.08). Treatment group and season were associated with differences in milk yield (P ≤ 0.02). Milk yield was 1.0 kg/cow per day greater (P = 0.02) in POST cows, while 4% FCM and ECM were 3.6 and 4.1 kg/day greater (P ≤ 0.01), respectively, following the DFM supplementation. Cows in the winter and spring produced more milk (P < 0.01) than in the fall and summer. For milk composition (kg and %), positive changes were observed and associated with the DFM supplementation period (P ≤ 0.07). The occurrence of adverse heath events and mortality rate were observed to be reduced (P < 0.001) from 32.8 and 1.6% to 23.7 and 0.7% for PRE and POST periods, respectively. Among the individual adverse health outcomes, mastitis, ketosis, metritis, displaced abomasum, and pneumonia occurrence were significantly reduced in POST vs. PRE (P ≤ 0.02). Treatment group × season interactions were observed for both conception and abortion rates (P ≤ 0.03); however, the interactions were noted mainly because of the season effect, given that within the same season, no treatment differences were observed (P ≥ 0.14). No treatment effects were observed either on conception or abortion rate (P ≥ 0.31). In summary, in this retrospective before-and-after study, B. licheniformis 809 and B. subtilis 810 supplementation was associated with an improved milk production, composition, and the health of the herd, while maintaining the reproductive performance of the commercial farm in Argentina.

PMID:
42829703
Bibliographic data and abstract were imported from PubMed on 04 Oct 2026.

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