Accuracy and precision of diets fed to close-up cows on dairy farms and its association with early lactation performance.

Ensuring a consistent ration is critical for maximizing lactating cow performance, but this is not known for dry cows. The objectives of this cohort observational study were to: (1) characterize close-up dry cow diets fed on commercial farms in Ontario, Canada, (2) describe the accuracy of the nutrient composition between the formulated close-up diet and the diet offered to the cows, (3) describe the precision of the close-up diets across time, and (4) explore potential associations of that accuracy and precision with blood metabolic parameters and milk yield of cows in early lactation. Forty freestall dairy farms were visited once every 4 wk, for a total of 6 visits to each farm, from April to October 2022.

Short communication: Association between prepartum subclinical magnesium imbalance and postpartum diseases in grazing dairy cows in Southern Chile.

This study aimed to evaluate the relationship between prepartum subclinical hypomagnesemia (pre-SHMg) and the occurrence of dystocia, metritis, clinical mastitis, lameness, and subclinical hypomagnesemia postpartum (post-SHMg) in pasture-based dairy cows. Also, the difference in means of prepartum magnesium (Mg) concentration by postpartum health events was evaluated. A total of 890 dairy cows from 32 commercial farms located in southern Chile were enrolled.

Associations of cow- and herd-level factors during the dry period with indicators of udder health in early-lactation cows milked by automated milking systems.

This observational study aimed to determine the association of cow-level factors and herd-level housing and management practices during the dry period with indicators of udder health in early-lactation cows in automated milking system (AMS) herds. Data were collected from 166 commercial AMS dairy farms (mean ± standard deviation = 116 ± 111 milking cows; range = 39 to 1,200) across Canada between October 2018 and September 2020. Information on herd demographics, housing, and management practices was obtained on each farm using 2 surveys.