Supplementing lactating dairy cows with a vitamin B12 precursor, 5,6-dimethylbenzimidazole, increases the apparent ruminal synthesis of vitamin B12

Meta-analysis of apparent ruminal synthesis and postruminal flow of B vitamins in dairy cows

As milk production has significantly increased over the past decade(s), existing estimates of the B-vitamin needs of the modern dairy cow are currently being reconsidered, as suboptimal B-vitamin supply may affect metabolic efficiency. At the same time, however, "true" (i.e., biologically active forms, excluding nonfunctional analogs) B-vitamin supply also cannot be adequately estimated by dietary intake, as the rumen microbiota has been shown to play a significant role in synthesis and utilization of B vitamins. Given their complex impact on the metabolism of dairy cows, incorporating these key nutrients into the next generation of mathematical models could help to better predict animal production and performance. Therefore, the purpose of this study was to generate hypotheses of regulation in the absence of supplemental B vitamins by creating empirical models, through a meta-analysis, to describe true B-vitamin supply to the cow (postruminal flow, PRF) and apparent ruminal synthesis (ARS). The database used for this meta-analysis consisted of 340 individual cow observations from 15 studies with 16 experiments, where diet and postruminal digesta samples were (post hoc) analyzed for content of B vitamins (B₁, B₂, B₃, B₆, B₉, B₁₂). Equations of univariate and multivariate linear form were considered. Models describing ARS considered dry matter intake (DMI, kg/d), B-vitamin dietary concentration [mg/kg of dry matter (DM)] and rumen-level variables such as rumen digestible neutral detergent fiber (NDF) and starch (g/kg of DM), total volatile fatty acids (VFA, mM), acetate, propionate, butyrate, and valerate molar proportions (% of VFA), mean pH, and fractional rates of degradation of NDF and starch (%/h). Models describing PRF considered dietary-level driving variables such as DMI, B-vitamin dietary concentration (mg/kg of DM), starch and crude protein (g/kg of DM) and forage NDF (g/kg of DM). Equations developed were required to contain all significant slope parameters and contained no significant collinearity between driving variables. Concordance correlation coefficient was used to evaluate the models on the developmental data set due to data scarcity. Overall, modeling ARS yielded better-performing models compared with modeling PRF, and DMI was included in all prediction equations as a scalar variable. The B-vitamin dietary concentration had a negative effect on the ARS of B₁, B₂, B₃, and B₆ but increased the PRF of B₂ and B₉. The rumen digestible NDF concentration had a negative effect on the ARS of B₂, B₃, and B₆, whereas rumen digestible starch concentration had a negative effect on the ARS of B₁ and a positive effect on the ARS of B₉. In the best prediction models, the dietary starch increased PRF of B₁, B₂, and B₉ but decreased PRF of B₁₂. The equations developed may be used to better understand the effect of diet and ruminal environment on the true supply of B vitamins to the dairy cow and stimulate the development of better-defined requirements in the future.

Evaluation of feeding ruminal-protected folate and cobalt pectinate on growth performance, carcass characteristics and plasma vitamin B12 and folate status in finishing beef steers

A large pen feedlot study was conducted to evaluate the response of yearling steers fed novel sources of rumen-protected folate (RPFA) and cobalt (cobalt pectinate; Co-PECT) on plasma levels of vitamin B12 and folate, growth performance, and carcass characteristics. A total of 2,100 steers (initial BW = 381 ± 45.2 kg.) were enrolled in the study at the time of randomization with 2,091 steers started on treatment diets following the transition to the finishing diet. A generalized randomized block design with sampling error (GRBD) with two treatments and 15 pen replications per treatment (5 blocks × 6 pens/block; 30 pens total with 70 steers/pen) were evaluated with pen serving as the experimental unit. A control (CON) treatment consisted of the standard finishing diet while the test diet consisted of the standard finishing diet providing 3.0 mg ∙ kg-1 DM of RPFA and 1.0 mg ∙ kg-1 DM total supplemental cobalt with approximately half coming from Co-PECT (TEST). Blood samples were collected from 60 randomly selected steers at study initiation and prior to shipping for plasma B12 and folate measurement. Data were analyzed with the model including fixed effects of treatment, block, and treatment within block interaction. Live growth performance was not affected by treatment; however, carcass-adjusted performance and hot carcass weight were numerically improved by TEST in 3 of the 5 blocks (treatment × within block interaction, P ≤ 0.03) of cattle. Plasma levels for both folic acid and vitamin B12 were extremely low at study initiation and increased over the course of the feeding period. Feeding TEST increased (P < 0.01) plasma B12 levels compared to CON by the completion of the trial; however, mean levels would still be considered marginal. Plasma folate was lower (P < 0.05) in TEST steers at the beginning of the study, with no difference between treatments by the time cattle were shipped. Results suggested that cattle coming into the feedlot may be of low or marginal status in both plasma folate and vitamin B12. While the status of folate and B12 improved in both CON and TEST with days on feed, providing RPFA and Co-PECT further helped improve vitamin B12 status; although, overall levels remained low, which may have affected the overall response to RPFA. Additional research is required to better understand the role of B vitamin supplementation for growing-finishing feedlots and develop methods for assessing the status and improving potential responses.

Relationship between Vitamin B12 and Cobalt Metabolism in Domestic Ruminant: An Update

Cobalt, as a trace element, is essential for rumen microorganisms for the formation of vitamin B12. In the metabolism of mammals, vitamin B12 is an essential part of two enzymatic systems involved in multiple metabolic reactions, such as in the metabolism of carbohydrates, lipids, some amino acids and DNA. Adenosylcobalamin and methylcobalamin are coenzymes of methylmalonyl coenzyme A (CoA) mutase and methionine synthetase and are essential for obtaining energy through ruminal metabolism. Signs of cobalt deficiency range from hyporexia, reduced growth and weight loss to liver steatosis, anemia, impaired immune function, impaired reproductive function and even death. Cobalt status in ruminant animals can be assessed by direct measurement of blood or tissue concentrations of cobalt or vitamin B12, as well as the level of methylmalonic acid, homocysteine or transcobalamin in blood; methylmalonic acid in urine; some variables hematological; food consumption or growth of animals. In general, it is assumed that the requirement for cobalt (Co) is expressed around 0.11 ppm (mg/kg) in the dry matter (DM) diet; current recommendations seem to advise increasing Co supplementation and placing it around 0.20 mg Co/kg DM. Although there is no unanimous criterion about milk production, fattening or reproductive rates in response to increased supplementation with Co, in some investigations, when the total Co of the diet was approximately 1 to 1.3 ppm (mg/kg), maximum responses were observed in the milk production.

Short communication: Potential prediction of vitamin B12 concentration based on mid-infrared spectral data using Holstein Dairy Herd Improvement milk samples

The purpose of this study was (1) to predict the quantitative concentration of vitamin B₁₂ in milk using mid-infrared (MIR) spectrometry, and (2) to evaluate the potential of MIR spectra to discriminate different clusters of records based on their B₁₂ concentration. Milk samples were collected from 4,340 Holstein cows between 3 and 592 d in milk and located in 100 herds. Samples were taken using in-line milk meters and divided into 2 aliquots: one for MIR spectrometry and the other for B₁₂ concentration reference analyses by radioassay. Analyses were performed on 311 selected spectral wavelengths. A partial least squares regression model was built to quantify B₁₂ concentration. Discriminant analysis was used to isolate B₁₂ concentration clusters. A B₁₂ concentration threshold was set at 442 ng/dL, because this represents the cutoff value for a 250-mL glass of milk to fulfill 46% of the daily vitamin B₁₂ recommended dietary allowance for individuals 14 yr or older. For each analysis, records coming from two-thirds of herds were used to calibrate prediction equations, and the remaining records (one-third of herds for validation) were used to assess the prediction performance. In the case of discriminant analysis, validation sets were divided into evaluation sets (one-third of herds) to obtain alternate probability cutoffs and in test sets (two-thirds of herds) to validate equations. Spectral and B₁₂ concentration outliers were identified by calculating standardized Mahalanobis distance and with a residual analysis, respectively (n = 3,154). Regarding quantitative B₁₂ concentration, cross-validation and validation coefficients of determination averaged 0.51 and 0.46, respectively, which are relatively low, which would limit the potential use of the developed quantitative equations. In addition, root mean square errors of prediction of cross validation and validation sets averaged 88.9 and 94.7 ng/dL, respectively. Area under the receiver operating characteristic curve of test sets averaged 0.81 based on the 442 ng/dL threshold, which could be considered to represent good accuracy of classification. However, the false discovery rate averaged 36%. In summary, models predicting quantitative B₁₂ concentration had low cross-validation and validation coefficients of determination, limiting their use, but the proposed discriminant models could be used to identify milk samples with naturally high B12.

Methods and approaches to estimate B vitamin status in dairy cows: Knowledge, gaps and advances

Clinical symptoms of B vitamin deficiency are rarely observed in ruminants because these vitamins are synthesized by the rumen microbiota. However, over the last decades, numerous reports of beneficial effects on production and metabolic efficiency of dairy cows have been published supporting that, under some conditions, B vitamin subclinical deficiency is present in these animals. Due to their roles as coenzymes or cofactors in major metabolic pathways, an adequate supply in B vitamins is critical to optimize metabolic efficiency. Nowadays, taking into account the growing interest for the Smart Farming concept, fulfilling ruminant requirements for B vitamins according to their physiological stage under different feeding management cannot be neglected. In dairy cows, B vitamin supply is greatly dependent of the activity of the ruminal microbiota. Indeed, the amount of vitamins reaching the small intestine is dependent of the utilization of the vitamins provided by the diet and their synthesis by the microorganisms present in the rumen. The two major challenges faced to determine B vitamin status of ruminants are the difficulty to estimate B vitamin supply due to the lack of knowledge on factors driving the fate of B vitamins in the digestive tract, especially in the rumen, and the choice and thresholds of biomarkers reflecting adequately the animal status. The present paper aims to present the actual state of knowledge on the methodological approaches used to estimate B vitamin supply and status of ruminant and to point out future research orientations.

Construction of Fluorescent Analogs to Follow the Uptake and Distribution of Cobalamin (Vitamin B12) in Bacteria, Worms, and Plants

Vitamin B₁₂ is made by only certain prokaryotes yet is required by a number of eukaryotes such as mammals, fish, birds, worms, and Protista, including algae. There is still much to learn about how this nutrient is trafficked across the domains of life. Herein, we describe ways to make a number of different corrin analogs with fluorescent groups attached to the main tetrapyrrole-derived ring. A further range of analogs were also constructed by attaching similar fluorescent groups to the ribose ring of cobalamin, thereby generating a range of complete and incomplete corrinoids to follow uptake in bacteria, worms, and plants. By using these fluorescent derivatives we were able to demonstrate that Mycobacterium tuberculosis is able to acquire both cobyric acid and cobalamin analogs, that Caenorhabditis elegans takes up only the complete corrinoid, and that seedlings of higher plants such as Lepidium sativum are also able to transport B₁₂.