Rumen degradable protein levels on fatty acid profile of rumen bacteria and milk fat of dairy cows supplemented with calcium salts of fatty acids.

This study aimed to evaluate the effects of calcium salts of fatty acids (CSFA) from soybean oil in diets with different levels of rumen degradable protein (RDP) on bio-hydrogenation extent, and fatty acid (FA) profile intake, omasal digesta, rumen bacteria, and milk fat. Eight Holstein lactating cows were used in a replicated 4 × 4 Latin square design. Treatments were arranged in a 2 × 2 factorial design with two CSFA levels (0 or 33.2 g/kg DM of CSFA) and two RDP levels (98.0 or 110 g/kg DM). There was RDP and CSFA interaction effect on the omasal flow of total FA and some specific FA. Only in -CSFA diets, the higher RDP level increased omasal flow of total FA. Dietary RDP levels did not affect the FA profile of bacteria and milk fat. Feeding CSFA reduced or tended to reduce the bacterial proportion of C15:0, C16:0, C16:1, C17:0, and C18:0 FA and decreased the concentrations of short- and medium-chain FA (<18C) and increased the concentrations of unsaturated and long-chain FA (≥18C) in milk fat. Feeding CSFA of soybean oil increases the intake and omasal flow of FA and augments unsaturated FA content in bacteria pellets and milk fat.

Feeding reduced levels of trace minerals in proteinate form and selenium-yeast to transition cows: Performance, trace minerals, and antioxidant status, peripheral neutrophil activity, and oocyte quality.

An experiment was conducted to evaluate the effects of inorganic trace minerals (TM) and reduced levels of TM by using proteinate forms of Co, Zn, Mn, and Cu, and Se-yeast in diets of transition cows on performance, TM concentrations in colostrum, plasma, and liver, blood metabolites, antioxidant status, peripheral neutrophil activity, and oocyte quality. Thirty-two Holstein cows (22 multiparous and 10 primiparous cows) were enrolled in this study from 30 d before the expected calving date to 56 DIM. Cows were blocked according to body condition score, parity, and previous milk yield and randomly assigned to one of the following treatments: control (CON), with TM (Zn, Cu, Mn, and Co) supplied in form of sulfate and Se as sodium selenite to meet or exceed requirement estimates of the National Research Council; and proteinate trace minerals (PTM), with TM supplied bound with AA and peptides at 50% of CON levels and inorganic Se replaced with Se-yeast at 100% of CON level. Treatments were supplied until 56 DIM. Eight cows were removed from the study because of early calving (n = 3) or health issues (n = 5); thus, data of 24 cows (16 multiparous and 8 primiparous cows) were used in the statistical analysis. No differences between treatments were detected on nutrient intake or digestibility. Total excretion of purine derivatives was decreased when feeding PTM during the prepartum period. Feeding reduced levels of TM in proteinate form resulted in greater yield of milk (27.7 and 30.9 kg/d for CON and PTM, respectively) and protein (0.890 and 0.976 kg/d) between wk 5 and 8 of lactation. No treatment differences were detected for feed efficiency, milk somatic cell count, and milk urea nitrogen. Cows fed PTM had lower milk fat concentration during the 56 d of evaluation (4.08 and 3.74% for CON and PTM, respectively). Selenium concentration was greater in colostrum of cows fed PTM compared with CON (48.5 and 71.3 µg/L for CON and PTM, respectively), whereas Zn, Cu, and Mn concentrations were not different. Cows fed PTM showed lower liver Cu concentration compared with CON (51.4 and 73.8, respectively). Plasma concentrations of Mn and Zn were lower, but plasma Se concentration tended to be higher with PTM treatment. Feeding PTM resulted in greater blood concentrations of urea-N (16.6 and 18.2 mg/dL for CON and PTM, respectively) and ß-hydroxybutyrate (0.739 and 0.940 mmol/L). Counts of lymphocytes were higher with PTM but counts of monocytes were lower in complete blood cell count. No differences were observed in serum concentrations of superoxide dismutase and glutathione peroxidase. No differences were detected in phagocytosis and oxidative burst potential of neutrophils after incubation with bacteria. Cows fed PTM had fewer viable oocytes per ovum pick-up in comparison with CON (8.00 and 11.6). Feeding PTM to transition cows may sustain performance without altering neutrophil activity despite some alterations in blood TM concentrations. More studies should be performed to evaluate production and fertility measurements when reducing TM dietary levels by using proteinate forms and Se-yeast with larger number of animals.