Larissa Schneider Gheller

The objective of this study was to evaluate the effects of sodium butyrate and organic zinc supplementation, alone or combined, on performance, zinc metabolism, blood parameters, and gut health in Holstein calves highly challenged by heat and diarrhea during the pre-weaning and weaning periods. Forty-eight male calves were assigned to one of four treatments: control (CON), SB (3 g/kg of sodium butyrate in dry matter [DM]), OZn (262 mg/kg of organic zinc in DM), or SBOZn (3 g/kg of sodium butyrate and 262 mg/kg of organic zinc in DM). Calves were monitored from days 7 to 63 for feed intake, weight gain, body morphometry, fecal score, and blood parameters. Zinc balance was evaluated from days 45 to 49, and 24 calves were slaughtered on day 64 for jejunal sampling to assess tight junction gene expression. Diarrhea incidence was high (>90%) across groups. Fecal scores varied over time but did not differ between treatments. The OZn and SBOZn groups had higher Zn intake, with greater absorption and retention of the mineral compared to the CON and SB groups. Additionally, the OZn group tended to have higher serum Zn concentrations. SB and OZn, separately or combined, had limited effects and did not consistently improve the performance or health of calves highly challenged during pre-weaning and weaning.

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. At each visit, samples of the close-up diet were collected and analyzed for DM content and chemical composition. Close-up diet formulations were also obtained by each farm's nutritionists. During each visit, fresh cows (0 to 14 DIM) had blood samples taken for blood metabolites. The same cows were also monitored for milk yield up to 120 DIM. Multivariable models were used to analyze associations between variability (in relation to the formulated diet and across time) of nutrients in the close-up diet, as measured by CV, and outcomes in fresh cows. Corn silage (67.6% of farms) and straw (24.3% of farms) were the predominant primary forage sources used in the close-up dry cow diets. Soybean meal (37.8% of farms) and canola meal (18.9% of farms) were the main ingredients used as primary concentrate sources. Overall, the diets offered did not accurately represent the formulated diets. With the exception of NE_L, the CV for the other nutrients were all greater than 5%. Diet variability, both between fed and formulated diets and from visit to visit during the close-up period, was associated with metabolic markers and dairy cow production. Lower variability in NFC between the fed and formulated diets was associated with better liver health index scores. Visit-to-visit variability in fat percent and NFC percent were associated with blood BHB concentrations, and NFC percent variability was associated with blood glucose levels. Serum nonesterified fatty acids concentrations were associated with visit-to-visit variability in DM percent and CP percent. These results underscore the importance of maintaining consistency between diet formulations and feeding practices over time to optimize early lactation dairy herd performance and health, granted that these diets are correctly formulated to meet the nutritional needs of cows in the close-up period and applied with recommended feeding practices.

This study evaluated the effects of homolactic bacteria and molasses (MOL) in whole‐plant soybean silage on dry matter (DM) losses, content of organic acids, bromatological composition, in situ degradation of DM and aerobic stability. Mini‐silos ( n = 200) were blocked ( n = 5) by phenological stage and assigned into a 2×2 factorial treatment arrangement with 2 levels of microbial inoculation (INO, 0 or 10 ⁵ colony forming units of Lactobacillus plantarum and Pediococcus pentosaceus per kg of fresh forage) and 2 levels of powdered MOL (0 and 40 g/kg fresh forage). Mini‐silos were opened after 90 days of fermentation. Total losses were lower in silos with MOL. Whole‐plant soybean ensiled with the combination of INO and MOL had the highest DM recovery. Adding MOL increased lactic acid content and decreased ammonia nitrogen content (marker of proteolysis), pH and buffering capacity. MOL reduced the contents of NDF. Silage with both INO and MOL had the highest DM content. MOL increased DM degradation. No effects were detected on aerobic stability. INO does not show positive effects on soybean silage nutritive quality when not associated with MOL. Molasses has a positive impact on whole‐plant soybean silage by decreasing fermentation losses and pH, while increasing silage nutritive value.

This study evaluated the effects of feeding an ultra-diluted complex to dairy cows during the transition period and early lactation. Thirty multiparous pregnant dairy cows were blocked and randomly assigned to either a placebo control (CON) group or ultra-diluted complex (UD) group. The CON group received a placebo (basal diet + 40 g/cow/day of expanded silicate), while the UD group received the ultra-diluted complex (basal diet + 40 g/cow/day of PeriParto Transição–RealH, composed of ultra-diluted substances + vehicle: expanded silicate). Cows were evaluated from 30 days before the expected calving date until 60 days in milk (DIM) for sample and data collection. Post-partum dry matter intake (DMI) was not affected by the treatment. Cows fed UD had higher DMI relative to BW. Feeding UD increased milk lactose content and decreased milk protein content. Cows fed UD had lower somatic cell counts in the third and fourth week of lactation. Cows fed UD showed a tendency for higher liver health index. Using UD during the transition period and early lactation may benefit liver and udder health of dairy cows with no detrimental effect on milk performance.

Compost-bedded pack barns (CB) are receiving increasing attention as a housing system that can potentially improve the welfare of dairy cows. This study characterized the frequency and profile of pathogens isolated from clinical (CM) and subclinical (SCM) mastitis in dairy cows housed in CB. It evaluated the association between mastitis occurrence and bedding characteristics in CB systems. Over six months, seven dairy herds were visited monthly for milk and bedding sample collections. Milk samples from mastitis cases were submitted to microbiological identification by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF MS). Bedding samples were submitted to physical-chemical (pH, organic matter, moisture, and carbon to nitrogen ratio) and microbiological counting (total bacterial counts, coliforms, streptococci, and staphylococci) analyses. Regression analysis was used to determine the association between mastitis occurrence and CB characteristics. Our results showed that Escherichia coli and environmental streptococci were the most frequently isolated pathogens from CM cases, while Staphylococcus chromogenes and contagious pathogens (Staphylococcus aureus and Streptococcus agalactiae) were the most commonly isolated from SCM cases. Bedding moisture content was positively associated with the incidence of CM. The bedding carbon to nitrogen ratio was negatively associated with the incidence of SCM, and the bedding total bacteria counts tended to be associated with the incidence of SCM. Bedding counts of coliforms positively associated with the prevalence of SCM. Our results can support decision-makers in the dairy industry seeking strategies for bedding management and mastitis control.