Background: This study aimed to verify whether adding a combination of additives (blend) to the diet of dairy calves after weaning can improve animal performance and health and influence the profile of ruminal short-chain fatty acids and intestinal microbiota. Methods: We used 35 Holstein calves, males, with an average age of 70 days and an average body weight of 68 kg. The treatments used were negative control (T-0: without additive), positive control (T-Control: flavomycin + monensin), T-500 (500 g blend/ton), T-1000 (1000 g blend/ton), and T-1500 (1500 g blend/ton). The additives were classified as zootechnical (probiotics, prebiotics, and essential oils of cinnamon and oregano) and nutritional additive (minerals). Results: Weight gain and daily weight gain were higher for calves in the T-Control, T-500, and T-1000 groups. The concentration of heavy-chain immunoglobulins was higher in the blood of calves in the T-Control and T-500 groups when compared to the other groups. In the T-1500 groups, higher levels of reactive oxygen species were observed, while, in the T-0 and T-1500 groups, higher levels of TBARS and glutathione S-transferase activity were detected. The 15 abundant microorganisms in the calves’ feces, regardless of treatment, were Treponema suis, Treponema saccharophilum, Faecalibacterium prausnitzii, Pseudoflavonifractor sp., Roseburia faecis, Rikenellaceae, Enterobacteriaceae_f, Clostridium sp., Roseburia intestinalis, Aeromonadales_o, Prevotella copri, Treponema succinifaciens, Eubacterium sp., Treponema porcium, and Succinivibrio sp. The T-1000 group showed greater alpha diversity for the intestinal microbiota than T-Control, T-0, and T-500. The additive combination (T-1000) increased the bacterial activity in the ruminal fluid, and the animals of T-1000 had a higher concentration of short-chain fatty acids compared to T-0 and T-1500; this difference is because, in these calves, the production of acetic, butyric, and propionic acid increased. Conclusions: The combination of additives had positive effects on animal health, ruminal volatile fatty acid production, and intestinal microbiota, resulting in animals with more significant weight gain and feed efficiency.

This study evaluated the effect of different amounts of marine microalgae (Schizochytrium limacinum) via milk on performance, serum constituents and antioxidant indicators of dairy calves. Twenty-four Holstein calves were distributed to one of four treatments (six replicates) according to a completely randomized design: a control treatment (without microalgae), or microalgae supplementation at 6, 12 and 18 grams of microalgae per day supplied via milk. Two blood samples were taken, at 21 and 42 days of the experiment, to measure activities of antioxidant enzymes: glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD) as well as levels of reactive oxygen species (ROS). The supplementation of increased amount of microalgae did not influence dry matter intake (DMI) and performance (P>0.05). At the 21 days of life, there was a linear increase in serum protein (P = 0.03), globulin (P = 0.006) and in SOD activity (P = 0.05). Linear reduction in ROS (P = 0.001) and a quadratic effect for heavy immunoglobulin G (IgG) (P = 0.02) were observed as the microalgae amounts increased. Close to weaning, at 42 days, serum globulin (P = 0.003), GST (P = 0.002) and SOD (P = 0.02) linearly increased with the inclusion of microalgae. Conversely, enzymatic activity of CAT showed a quadratic effect (P = 0.05). Supplementation of microalgae via milk did not influence intake and performance dairy calves. However, the use of microalgae as a feed additive to dairy calves at amount of 6 g/d is recommended due to its stimulation of antioxidant enzymes and reduction on serum levels of free radicals.

This study evaluated of the effects of açai oil during the close-up dry period of Holstein cows on colostrum quality, as well as on the immune and antioxidant responses of their calves. Sixteen multiparous cows were assigned randomly to two treatments: 1) CONTROL (n = 8) - 4.48% of soybean oil/concentrate; 2) AÇAI (n =8) - 4.48% of açai oil/concentrate. Cows fed with açai oil had greater (P≤0.04) colostrum concentrations of immunoglobulins (Ig) G (1st and 2nd milking), IgG heavy chains, IgA (only at 1st milking), alpha-lactalbumin (1st milking), total protein, and antioxidant capacity against peroxyl radicals (only at 1st milking). Cows fed with açai oil had greater serum concentrations of globulin (only on the day of calving) and total protein (only on the day of calving) (P = 0.03). Calves born of cows fed with açai oil had greater serum concentrations of total protein (only 24 and 48 h after calving) and serum concentration of IgG heavy chain (only 24 h after calving) and globulin (only 24 and 48 h after calving) (P = 0.01). These data suggest that the addition of açai oil in the cow feed during the close-up dry period boosted immunity in their calves by altering the composition of colostrum.

Brain abscesses in ruminants often arise from primary infection foci, leading to an unfavorable prognosis for affected animals. This highlights the need for comprehensive studies on brain abscesses across different ruminant species. We retrospectively investigated medical records of epidemiological, clinical, neuroimaging, anatomopathological, and bacteriological findings in six ruminants (three goats, two cows, and one sheep) diagnosed with brain abscesses. All animals studied were female. Apathy (50%), compulsive walking (33%), decreased facial sensitivity (33%), head pressing (33%), seizures (33%), semicomatous mental status (33%), strabismus (33%), unilateral blindness (33%), and circling (33%) represented the most common neurologic signs. Leukocytosis and neutrophilia were the main findings in the hematological evaluation. Cerebrospinal fluid (CSF) analysis revealed predominant hyperproteinorrachia and pleocytosis. In three cases, computed tomography or magnetic resonance imaging were used, enabling the identification of typical abscess lesions, which were subsequently confirmed during postmortem examination. Microbiological culture of the abscess samples and/or CSF revealed bacterial coinfections in most cases. Advanced imaging examinations, combined with CSF analysis, can aid in diagnosis, although confirmation typically relies on postmortem evaluation and isolation of the causative agent. This study contributes to clinicopathological aspects, neuroimages, and bacteriological diagnosis of brain abscesses in domestic ruminants.