A comprehensive integration of factors affecting vitamin B12 concentration in milk of Holstein cows: Genetic variability, milk productivity, animal characteristics, and feeding management

Daily vitamin B12 (VB12) requirements of humans can naturally be fulfilled by animal product consumption, especially products from ruminants because of bacteria dwelling in their rumen. Indeed, only bacteria can synthesize this vitamin. Milk is hence an excellent source of VB12. This cross-sectional study was undertaken to unravel factors, such as genetic variation, diet and cow characteristics, and milk production, explaining the large variation in milk VB12 concentration among cows by using an integrative approach. Milk samples from 2 consecutive milkings were collected from 3,533 Canadian Holstein cows (1,239 first, 932 second, and 1,362 third and more lactations) located in 99 herds with various feeding management. For the purpose of genetic variation analysis, pedigrees were traced back for 3 complete generations for each sire and dam. A total of 10,021 identities were used in the subsequent genetic analyses. Milk VB12 averaged 4.2 ng/mL with a range between 0.7 and 9.0 ng/mL. Dietary fiber (NDF from forage, dietary NDF, ADF, and lignin) increased and dietary components related to energy (NFC, starch, NEL, and percentage of concentrate) decreased VB12 in milk. Milk VB12 varied with DIM, with a similar pattern as milk fat and protein concentration lactation curves. Milk VB12 increased as age at calving increased. When disregarding the herd variance, the heritability value was 0.37, meaning that milk VB12 can be modified by genetic selection. The final model including factors related to the diet, animal characteristics and milk productivity, and genetic variation explained 79% (pseudo-R2) of the milk VB12 variation. When excluding the random effect of the cow (i.e., excluding the animal and genetic relationships), the pseudo-R2 dropped to 43%, reinforcing the importance of genetic variation in explaining milk VB12 variation. To our knowledge, the present study is the most comprehensive evaluation of factors affecting milk VB12 variation including the greatest number of cows from various lactation stages.

Longitudinal Data to Assess Relationships among Plasma Folate, Vitamin B12, Non-esterified Fatty Acid, and β-Hydroxybutyrate Concentrations of Holstein Cows during the Transition Period

It is well established that the plasma metabolite profile changes during metabolic dysfunction, such as elevated non-esterified fatty acid (NEFA) release when body reserve mobilization is excessive in early lactation cows. Relationships between changes in plasma concentrations of metabolites caused by a metabolic impairment and the status of vitamins, such as folates and vitamin B12, have barely been studied in cattle. This study was undertaken to assess relationships between peripartum plasma concentrations of folates, vitamin B12, NEFA, and beta-hydroxybutyrate (BHB). Longitudinal data of 48 multiparous Holstein cows from 5 studies were taken from days -14 to 21 relative to calving. Blood samples were taken weekly before calving and either twice or thrice per week postpartum, and plasma was analyzed for folate, vitamin B12, NEFA, and BHB concentrations. Postpartum plasma NEFA and BHB concentrations were negatively related to plasma folate concentration at days -14 and -7 relative to parturition, whereas the opposite relationship was noted for the plasma vitamin B12:folate ratio. The plasma folate and NEFA areas under the curve from the whole studied period were negatively associated, and the opposite was observed with the association between the plasma vitamin B12:folate ratio and NEFA as well as the BHB areas under the curve. The results suggest that there is an increased use of folate for metabolic functions during elevated concentrations of plasma NEFA and BHB. Future research should focus on finding an optimal plasma vitamin B12:folate ratio to favor cow health during the challenging period of parturition.

The Importance of B Vitamins in Enhanced Precision Nutrition of Dairy Cows: The Case of Folates and Vitamin B12

Dairy cow diets are generally balanced for energy and major nutrients with B vitamins generally assumed not to be limiting, in spite of their role as coenzymes, essential to many metabolic reactions in protein, carbohydrate and lipid metabolism. Assuming adequacy of B-vitamin supply may explain some of the discrepancies between the outcomes of metabolic prediction models and measured cow performance. In lactating dairy cow, the amount of B vitamins from the diet and synthesized by the ruminal microbiota is generally sufficient to prevent deficiency symptoms and, as such, is assumed to fulfill requirements. However, reports of beneficial effects of B-vitamin supplementation on dairy cow performance suggest that B-vitamin supply is sometimes lower than its needs, as an insufficient B-vitamin supply decreases metabolic efficiency by driving a shift towards alternative metabolic pathways with greater energy cost. Using information on folates and vitamin B12 illustrated how meeting dairy cow needs for B vitamins should not be overlooked in formulation of rations for lactating dairy cattle. The present review discusses current knowledge and indicates areas presently impeded by the lack of research results, especially the limitations on the ability to estimate B vitamin need and supply.

Refining Knowledge of Factors Affecting Vitamin B12 Concentration in Bovine Milk

Simple Summary

Milk is considered a staple and complete food that contains several essential nutrients for humans. For instance, it is an excellent natural source of vitamin B₁₂ (B12) due to the presence in the bovine rumen of a myriad of bacteria and archaea capable of producing the vitamin. This vitamin is only produced by prokaryotic microorganisms; vegetal products do not naturally contain it. A 250-mL glass of milk contains about 46% of the daily recommended dietary allowance of B12 for individuals over 13 years old. However, B12 concentration is variable in milk; therefore, identifying factors contributing to its variation is critical to ensure a stable B12 supply for consumers. The aims of these experiments are to gather more knowledge on possible sources of variation in B12 concentrations in milk in order to optimize and stabilize its levels and thereby improve the perception of milk in terms of its health benefits. We observed that B12 concentration increases when the conditions of the rumen are optimal, such as with elevated pH. We also studied if bedding type—e.g., recycled manure solid bedding or straw, which has been reported to impact milk microbiota—could have an impact on milk B12 concentration. In this study, no such correlation was detected. This paper is one of a series seeking to elucidate factors responsible for variations in milk B12 concentration.

Abstract

Milk is an excellent source of vitamin B₁₂ (B12) for humans. Therefore, being able to guarantee a high and consistent concentration of this vitamin would enhance consumer perception of milk as a health food. The aim of the paper was to gather additional knowledge on factors that could explain B12 variation in cow milk through two observational studies: (1) to explore the relationship between milk B12 and ruminal conditions, such as pH and volatile fatty acid concentrations; and (2) to examine the impact of bedding on B12 concentrations in bulk tank milk. For study 1, a total of 72 milk and ruminal liquid samples were obtained from 45 Holstein cows fitted with ruminal cannula between 10 and 392 days of lactation. For study 2, bulk tank milk samples were obtained from 83 commercial herds; 26 herds used recycled manure solid bedding and 57 used straw bedding. Milk samples were analyzed for B12 using radioassay. Using principal component regression analysis, we observed that ruminal pH and the acetate:propionate ratio for cows receiving the early lactation ration were positively correlated with milk B12. Bedding did not influence milk B12 in bulk tanks, which averaged 4276 pg/mL. In conclusion, as B12 is synthesized by ruminal bacteria, optimizing ruminal conditions had a positive effect on milk B12, while bedding management had no influence.

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.

Correlations between the Composition of the Bovine Microbiota and Vitamin B12 Abundance

In this paper, we examined the microbiome of the bovine rumen, feces, and milk and attempted to understand how the bacterial communities at each site affected the production and movement of vitamin B₁₂ around the animal’s body. It was determined that the composition of the bovine rumen microbiome correlates well with vitamin B₁₂ concentration, indicating that the rumen microbiota may be a good target for manipulation to improve production of this important vitamin.

Vitamin B₁₂ is synthesized by prokaryotes in the rumens of dairy cows—and this has implications in human nutrition since humans rely on consumption of dairy products for vitamin B₁₂ acquisition. However, the concentration of vitamin B₁₂ in milk is highly variable, and there is interest in determining what causes vitamin B₁₂ variability. We collected 92 temporally linked rumen, fecal, blood, and milk sample sets from Holstein cows at various stages of lactation fitted with rumen cannula and attempted to define which bacterial genera correlated well with vitamin B₁₂ abundance. The level of vitamin B₁₂ present in each sample was measured, and the bacterial population of each rumen, fecal, and milk sample (n = 263) was analyzed by 16S rRNA-targeted amplicon sequencing of the V4 region. The bacterial populations present in the rumen, small intestine, and milk were highly dissimilar. Combined diet and lactation status had significant effects on the composition of the microbiota in the rumen and in the feces. A high ruminal concentration of vitamin B₁₂ was correlated with the increased abundance of Prevotella, while a low ruminal concentration of vitamin B₁₂ was correlated with increased abundance of Bacteroidetes, Ruminiclostridium, and Butyrivibrio. The ultimate concentration of vitamin B₁₂ is controlled by the complex interaction of several factors, including the composition of the microbiota. Bacterial consumption of vitamin B₁₂ in the rumen may be more important in determining overall levels than bacterial production.

IMPORTANCE In this paper, we examined the microbiome of the bovine rumen, feces, and milk and attempted to understand how the bacterial communities at each site affected the production and movement of vitamin B₁₂ around the animal’s body. It was determined that the composition of the bovine rumen microbiome correlates well with vitamin B₁₂ concentration, indicating that the rumen microbiota may be a good target for manipulation to improve production of this important vitamin.

Cross-sectional study of the effect of diet composition on plasma folate and vitamin B12 concentrations in Holstein cows in the United States and Canada

The objective of this cross-sectional study was to assess the variability of plasma folate and vitamin B₁₂ concentrations in lactating Holstein cows across the United States and Canada. We also evaluated the effect of diet composition and cow characteristics on folate and vitamin B₁₂ plasma vitamin concentrations. A total of 22 and 24 US and Canadian dairy herds were enrolled, totaling 427 and 476 cows at 10 to 197 days in milk across all US and Canadian herds, respectively. Blood samples were taken to analyze plasma folate and vitamin B₁₂ concentrations, and ingredients of the diet were collected to determine nutrient composition. To reduce the number of interdependent variables in the analysis of the association of diet composition with plasma vitamin concentrations, we conducted a principal component analysis. Plasma folate concentrations were lower for US cows [13.4 ng/mL, 95% confidence interval (CI): 12.7-14.2] than for Canadian cows (14.5 ng/mL, 95% CI: 13.7-15.2), and the opposite was observed for plasma vitamin B₁₂ concentrations (US 206 pg/mL, 95% CI: 192-221; Canada 170 pg/mL, 95% CI: 159-181). The highest plasma concentrations of both vitamins were observed in the Northwest region of the United States (Oregon and Washington). Cows in California had the lowest plasma folate concentrations, and cows in Québec and New York State had the lowest plasma vitamin B₁₂ concentrations. Plasma folate concentrations were higher for multiparous than for primiparous cows and plasma vitamin B₁₂ concentrations progressively increased from parity 1 to 3 and higher. For both studied vitamins, plasma concentrations were lower at 0 to 55 than at 56 to 200 days in milk. Of 3 principal components, the one associated with dietary carbohydrates was significantly correlated with plasma folate and vitamin B₁₂ concentrations. Indeed, plasma folate concentrations decreased with dietary fiber concentrations (i.e., neutral and acid detergent fibers and lignin) and increased with dietary nonfiber carbohydrate concentrations. We obtained the opposite results for plasma vitamin B₁₂ concentrations. Both multivariable models explained 41% (pseudo-R²) of the variation in plasma folate and vitamin B₁₂ concentrations. Information gathered in this study is the first step toward determining sources of variation in plasma folate and vitamin B₁₂ concentrations, as well as the vitamin status of cows.

Glucose and insulin responses to an intravenous glucose tolerance test administered to feed-restricted dairy cows receiving folic acid and vitamin B12 supplements

The present experiment was conducted to determine whether, during periods of negative energy balance, the increase in glucose availability, despite similar DMI and greater milk production, induced by a combined supplement of folic acid and vitamin B₁₂ was related to effects of insulin on metabolism. Sixteen multiparous Holstein cows averaging 45 days in milk (standard deviation: 3) were assigned to 8 blocks of 2 animals each according to their milk production (45 kg/d; standard deviation: 6) during the week preceding the beginning of the experiment. Within each block, they received weekly intramuscular injections of either saline (CON) or folic acid and vitamin B₁₂ (VIT) during 5 consecutive weeks. During the last week, the cows were fed 75% of their ad libitum intake during 4 d. Blood samples were taken the morning before starting the feed restriction and on the third day of feed restriction. On the fourth day of feed restriction, the daily meal was not served and an intravenous glucose tolerance test was performed. During the 4 wk preceding the feed restriction, milk production and DMI were not affected by treatments. During the feed restriction, the vitamin supplement tended to decrease milk fat concentration and increase milk concentration of lactose. Plasma concentrations of homocysteine, Ile, Leu, Val, and branched-chain AA increased in VIT cows during the restriction but not in CON cows. During the glucose tolerance test, insulin peak height was lower and insulin incremental positive area under the curve tended to be lower for VIT than for CON [83 (95% confidence interval, CI: 64-108) vs. 123 (95% CI: 84-180) µg·180 min/L, respectively]. Free fatty acid nadir was reached earlier for VIT than for CON [34 (95% CI: 26-43) vs. 46 (95% CI: 31-57) min, respectively]. Glucose area under the curve, clearance rate and peak height, insulin time to reach the peak and clearance rate, and free fatty acid nadir did not differ between VIT and CON. The reduction in insulin release during a glucose tolerance test without changes in glucose clearance rate or area under the curve suggests that the vitamin supplement improved insulin sensitivity in feed-restricted lactating dairy cows.

Milk β-hydroxybutyrate concentration measured by Fourier-transform infrared and flow-injection analyses from samples taken at different times relative to milking

Analysis of milk BHB concentration by Fourier-transform infrared (FTIR) spectrometry more frequently than regular milk testing could help dairy producers in decision making, particularly if it would be possible to use small hand-stripped samples (hereinafter simply called samples) taken between dairy herd improvement (DHI) test-samples analysed using DHI algorithms. The aim of this Research Communication was to evaluate milk BHB concentration and the prevalence of elevated milk BHB concentration analysed by FTIR spectrometry compared with flow-injection analysis (SKALAR) from samples taken at different times relative to the milking. A total of 293 early-lactation cows in 44 commercial dairy herds were involved in the study. Herds were visited once during the morning milking when a routine DHI test-sample was obtained using in-line milk samplers. Additional milk samples were taken by hand stripping as follows: (1) Just before connecting the milking machine; (2) immediately after removing the milking machine; (3) 3 h after milking and (4) 6 h after milking. Milk samples were analysed for BHB concentration by FTIR and SKALAR, the latter being the reference method. Milk BHB concentration from samples taken before milking was different between FTIR and SKALAR whereas no difference was noted for other sampling times, although milk BHB concentration rose as time after milking increased. Except for DHI test-samples for which prevalence was not different between analysis methods, prevalence of elevated milk BHB concentration (≥0.15 mmol/l) was greater for FTIR analysis. However, no difference in prevalence was observed between SKALAR and FTIR when using a threshold of ≥0.20 mmol/l. In summary, hand-stripped milk samples taken any time after removing the milking machine until 6 h after the milking can be recommended for FTIR analysis of elevated milk BHB concentration prevalence provided a threshold of 0.20 mmol/l is used.

Impact of diet management and composition on vitamin B12 concentration in milk of Holstein cows

As vitamin B12 is only synthesized by bacteria, ruminant products, especially dairy products, are excellent sources of this vitamin. This study aims to identify if diet and cow characteristics could affect vitamin B12 concentration in milk of dairy cows. Information on 1484 first, 1093 second and 1763 third and greater parity Holstein cows in 100 herds was collected during three consecutive milkings. During the first morning milking, all dietary ingredients given to cows were sampled and quantities offered were recorded throughout the day. Nutrient composition of ingredients was obtained by wet chemistry to reconstitute nutrient composition of the ration. Milk samples were taken with in-line milk meters during the evening milking of the 1st day and the morning milking of the 2nd day and were analyzed for vitamin B12 concentration. Milk yields were recorded and milk components were separately analyzed for each milking. Daily vitamin B12 concentration in milk was obtained using morning and evening vitamin B12 concentrations weighted with respective milk yield, then divided by daily yield. To decrease the number of interdependent variables to include in the multivariable model, a principal component analysis was carried out. Daily milk concentration of vitamin B12 averaged 3809±80 pg/ml, 4178±79 pg/ml and 4399±77 pg/ml for first, second and third, and greater lactation cows. Out of 11 principal components, six were significantly related to daily milk concentration of vitamin B12 when entered in the multivariable model. Results suggested that vitamin B12 concentration in milk was positively related to percentage of fiber and negatively related to starch as well as energy of the diet. Negative relationships were noted between vitamin B12 concentration in milk and milk yield as well as milk lactose concentration and positive relationships were observed between vitamin B12 concentration in milk and milk fat as well as protein concentrations. The percentages of chopped mixed silage and commercial energy supplement in the diet as well as cow BW were positively related to vitamin B12 in milk and percentages of baled mixed silage, corn and commercial protein supplement in the ration were negatively related to vitamin B12 concentration in milk. The pseudo-R2 of the model was low (52%) suggesting that diet and cow characteristics have moderate impact on vitamin B12 concentration in milk. Moreover, when entering solely the principal component related to milk production in the model, the pseudo-R2 was 46%. In conclusion, it suggests that studied diet characteristics have a marginal impact on vitamin B12 concentration in milk variation.