Graduate Student Literature Review: Exploring choline's important roles as a nutrient for transition dairy cows

In late gestation and in the first weeks postpartum, lipid droplets accumulate in the hepatic tissue resulting in approximately 40% to 50% of the dairy cows developing hepatic lipidosis in the first weeks of lactation. Elevated concentrations of triacylglycerol in the hepatic tissue are associated with increased risk of peripartum diseases and impaired productive performance. Cows with hepatic lipidosis need to dispose the excess of hepatic triacylglycerol, but this is a slow process in the bovine liver and relies on primary mechanisms such as complete oxidation and ketogenesis because of the limited export of triacylglycerols as lipoproteins. Choline is a lipotropic compound because, among other functions, it facilitates the export of lipids from the liver. Supplementing choline as rumen-protected choline (RPC) to diets of feed-restricted dairy cows reduces the degree of triacylglycerol infiltration into the hepatic parenchyma in part by enhancing export of triacylglycerol as nascent lipoprotein. The reduced accumulation of triacylglycerol in hepatic tissue in feed-restricted cows fed RPC might affect secondary pathways involved in hepatic disposal of fatty acids such as increased cellular autophagy and lipophagy and minimize endoplasmic reticulum stress response and hepatocyte inflammation. Collectively, these effects on secondary pathways might further reduce the severity of hepatic lipidosis in cows. One of the benefits of supplementing RPC is improved fat digestibility, perhaps because choline, through phosphatidylcholines, facilitates lipid transport within the enterocyte by increasing the synthesis of chylomicrons. Finally, when supplemented during the transition period, RPC improves productive performance of cows, irrespective of their body condition, that extends well beyond the period of supplementation. This review summarizes the current understanding of hepatic lipidosis in early lactation, recapitulates the absorption, transport and metabolism of choline, and discusses its role on hepatic metabolism and gastrointestinal functions, which collectively results in improved performance in dairy cows.

A Polyherbal Mixture with Nutraceutical Properties for Ruminants: A Meta-Analysis and Review of BioCholine Powder

BioCholine Powder is a polyherbal feed additive composed of Achyrantes aspera, Trachyspermum ammi, Azadirachta indica, and Citrullus colocynthis. The objective of this study was to analyze published results that support the hypothesis that the polyherbal product BioCholine Powder has rumen bypass choline metabolites through a meta-analysis and effect size analysis (ES). Using Scopus, Web of Science, ScienceDirect, PubMed, and university dissertation databases, a systematic search was conducted for experiments published in scientific documents that evaluated the effects of BioCholine supplementation on the variables of interest. The analyzed data were extracted from twenty-one publications (fifteen scientific articles, three abstracts, and three graduate dissertations available in institutional libraries). The studies included lamb growing-finishing, lactating ewes and goats, calves, and dairy cows. The effects of BioCholine were analyzed using random effects statistical models to compare the weighted mean difference (WMD) between BioCholine-supplemented ruminants and controls (no BioCholine). Heterogeneity was explored, and three subgroup analyses were performed for doses [(4 (or 5 g/d), 8 (10 g/d)], supplementation in gestating and lactating ewes (pre- and postpartum supplementation), and blood metabolites by species and physiological state (lactating goats, calves, lambs, ewes). Supplementation with BioCholine in sheep increased the average daily lamb gain (p < 0.05), final body weight (p < 0.01), and daily milk yield (p < 0.05) without effects on intake or feed conversion. Milk yield was improved in small ruminants with BioCholine prepartum supplementation (p < 0.10). BioCholine supplementation decreased blood urea (p < 0.01) and increased levels of the liver enzymes alanine transaminase (ALT; p < 0.10) and albumin (p < 0.001). BioCholine doses over 8 g/d increased blood glucose, albumin (p < 0.10), cholesterol, total protein, and globulin (p < 0.05). The ES values of BioCholine in retained energy over the control in growing lambs were +7.15% NEm (p < 0.10) and +9.25% NEg (p < 0.10). In conclusion, adding BioCholine Powder to domestic ruminants' diets improves productive performance, blood metabolite indicators of protein metabolism, and liver health, showing its nutraceutical properties where phosphatidylcholine prevails as an alternative that can meet the choline requirements in ruminants.

Effects of rumen-protected choline supplementation in Holstein dairy cows during electric heat blanket-induced heat stress

Dairy cows experiencing heat stress (HS) attempt to thermoregulate through multiple mechanisms, such as reducing feed intake and milk production and altering blood flow to increase heat dissipation. Effects of choline on energy metabolism and immune function may yield it a viable nutritional intervention to mitigate negative effects of HS. The primary objective of this experiment was to determine if supplementation of rumen-protected choline during, or before and during, an increased heat load would ameliorate the negative effects of HS on production and immune status. Heat stress was induced via an electric heat blanket model with a 3-d baseline period and 7-d HS period for all cows. Multiparous mid-lactation (208 ± 31 days in milk) Holstein cows were fed the same basal herd diet, blocked by pre-experiment milk yield, and randomly assigned to receive one of the following: (1) no rumen-protected (RP) choline (n = 7); (2) RP choline (60 g/d) via top-dress during the HS period (n = 8); or (3) RP choline (60 g/d) via top-dress during the baseline and HS periods (n = 8). Imposing HS via electric heat blanket raised respiration rate with all cows surpassing the HS threshold of 60 breaths/min. The increase in respiration rate tended to be ameliorated with either schedule of RP choline supplementation. Milk yield tended to increase when RP choline was supplemented in both the baseline period and during HS. Supplementation of RP choline tended to reduce blood fatty acid and triglyceride and tended to increase the revised quantitative insulin sensitivity check index. The role of RP choline supplementation to partially ameliorate the effects of HS should be further explored as a potential nutritional strategy to mitigate the negative consequences of HS on health and production.

Effects of unprotected choline chloride on microbial fermentation in a dual-flow continuous culture depend on dietary neutral detergent fiber concentration

Choline is usually supplemented as ruminally protected choline chloride to prevent its degradation in the rumen, but the effects of unprotected choline on ruminal fermentation are unclear. Some research indicates a possible role of dietary fiber on microbial degradation of choline; therefore we aimed to evaluate the effects of unprotected choline chloride on ruminal fermentation and to investigate whether those effects depend on dietary neutral detergent fiber (NDF) concentration. Our hypothesis was that dietary NDF concentration would influence choline chloride effects on microbial ruminal fermentation. We used 8 fermentors in a duplicated 4 × 4 Latin square with a 2 × 2 factorial arrangement, combining 2 factors: (1) dietary NDF concentration and (2) unprotected choline chloride supplementation. Resulting treatments are (1) 30%NDF/Ctrl [30% NDF control diet without supplemental choline (Cho)]; (2) 30%NDF/Cho [30% NDF diet plus 1.9 g of choline ion per kg of dry matter (DM)]; (3) 40%NDF/Ctrl (40% NDF control diet without supplemental choline); and (4) 40%NDF/Cho (40% NDF diet plus 1.9 g of choline ion per kg of DM). Four 10-d periods were completed, each consisting of 7 d for adaptation and 3 d for collection of samples for estimation of nutrient disappearance and daily average concentrations of volatile fatty acids and NH₃-N. In addition, kinetics of pH, acetate, and propionate were evaluated at 0, 1, 2, 4, 6, and 8 h after morning feeding. On the last day of each period, bacteria pellets were harvested for ¹⁵N analysis and N metabolism. Fixed effects of dietary NDF concentration, unprotected choline chloride supplementation, and their interaction (NDF × Cho) were tested using the MIXED procedure of SAS version 9.4 (SAS Institute Inc., Cary, NC). Choline tended to increase total volatile fatty acid concentrations and decreased acetate molar proportion regardless of dietary NDF concentration, but it increased propionate molar proportion and decreased acetate to propionate ratio only with the 30% NDF diet. Supplementing choline decreased NDF disappearance regardless of dietary NDF; however, organic matter disappearance tended to be reduced only when choline was added to 40% NDF. Our data indicate that unprotected choline chloride effects on ruminal fermentation depend on dietary NDF concentration, allowing for a greater propionate synthesis without decreasing organic matter disappearance when fed with a 30% NDF diet.

A Meta-Analysis on the Impact of the Supplementation of Rumen-Protected Choline on the Metabolic Health and Performance of Dairy Cattle

Simple Summary

During the first weeks of lactation, dairy cows typically experience negative energy balance, leading to the mobilization of energy reserves. This predisposes early lactating cows towards metabolic diseases, such as fatty liver syndrome and ketosis. The supplementation of rumen-protected choline (RPC) is a strategy to restrict negative effects associated with negative energy balance in early lactating cows, but reported effects are inconsistent. This meta-analysis revealed that the supplementation of RPC positively affected dry matter intake, but this effect was associated with increased milk yield, thus without improving energy balance and metabolic profile of the cows.

Abstract

After parturition, cows undergo negative energy balance leading to fat mobilization, predisposing them to fatty liver syndrome and ketosis with major consequences for health and reproduction. Supplementation of rumen-protected choline (RPC) has attracted major research efforts during the last decade, assuming that choline improves liver function by increasing very low-density lipoprotein exportation from the liver, thereby improving metabolic profiles, milk production, and reproduction. However, the effects of RPC on production, health, and reproduction have been inconsistent. Therefore, the aim of this meta-analysis was to evaluate the effects of RPC supplementation, starting from d 20 (± 12.2) ante partum to d 53 (± 31.0) postpartum, on feed intake, milk production performance and metabolic profiles of dairy cows early postpartum. Data analyses from 27 published studies showed an increase in postpartal dry matter intake (from on average 19.1 to 19.9 kg/d; p < 0.01) and milk yield (from on average 31.8 to 32.9 kg/d; p = 0.03) in cows receiving RPC. Milk fat yield and milk protein yield were also increased (p ≤ 0.05), without changing milk protein and fat contents. However, no interactive effects between cow’s milk yield level and RPC-supplementation as well as no dose-dependent effects of RPC supplementation were observed. Supplementing the diet with RPC showed no effects on blood metabolites (non-esterified fatty acids, beta-hydroxybutyrate, glucose, and cholesterol), independent of the milk yield level of the cows. An effect on liver triacylglycerol contents, incidence of ketosis, and mastitis could not be confirmed across all studies included in this meta-analysis. Also, the positive effects of RPC supplementation on reproductive performance were not consistent findings. In conclusion, supplementing RPC in lactating dairy cows showed positive effects on dry matter intake which likely caused the improved milk yield. However, RPC supplementation did not improve the metabolic health status of the cows. As several factors might be related to the responses to RPC, further research is needed to explore the precise mechanisms of RPC action in lactating cows, especially with regards to feed intake improvement and its related metabolic health-promoting potential in early lactating dairy cows.

Effect of choline chloride supplementation on milk production and milk composition of Etawah grade goats

Background

The effect of choline chloride supplementation through forced drinking combined with concentrate diets containing Ca-fish oil on milk production and milk composition of Etawah Grade goats was evaluated. Choline chloride is an essential component in ruminant diets as it is required for fat metabolism.

Method

The experiment was conducted in a completely randomized block design with three types of treatments and eight replications. The trial had two successive experimental periods; the first, during the eight weeks of late pregnancy, and the second, during the first 12 weeks of lactation. Twenty-four Etawah Grade does in the second gestation period were divided into three treatment groups. Commercial choline chloride 60 % in corncobs-based powder was used as a source of choline chloride. The treatments were no supplementation (control) and supplemented with either 4 g or 8 g/2days of choline chloride. Choline chloride was given to the animals through a forced drinking technique, after dissolving it in 60 ml drinking water. The initial body weight of does was 38.81 ± 3.66 kg. The does were penned individually, and were given fresh chopped King Grass ad libitum and 700 g/day of concentrate diets containing Ca-fish oil, starting eight weeks prior to expecting kidding and continuing for 12 weeks of parturition.

Results

All nutrient intakes were not significantly different (p > 0.05) among the treatments during the late pregnancy and the lactation periods. Supplementation did not affect (p > 0.05) the average daily gains and feed conversion ratio during pregnancy but gave effects (p < 0.05) on the average daily gains, feed conversion ratio and income over feed cost during lactation. The highest average daily milk yields and 4 % fat corrected milk yields were found in goats supplemented with 4 g/2days of choline chloride and increased by 17.00 % and 24.67 %, respectively, compared to the control. Moreover, milk composition percentage and milk constituent yields improved significantly (p < 0.05) in those supplemented with 4 g/2days of choline chloride.

Conclusion

The supplementation of 4 g/2days of choline chloride through forced drinking increased milk yields, the 4 % fat corrected milk yields, milk composition, milk constituent yields, and improved feed conversion ratio and income over feed cost of Etawah Grade goats.

Effects of supplementation of rumen-protected choline on growth performance, meat quality and gene expression in longissimus dorsi muscle of lambs

This study determined the effects of rumen-protected choline (RPC) on growth performance, blood lipids, meat quality and expression of genes involved in fatty-acid metabolism in young lambs. A total of 24 Dorper × Hu lambs (about 20 kg body weight) were kept in individual pens and fed diets with 0%, 0.25%, 0.50% and 0.75% RPC for 60 d. Supplementation of 0.25% RPC increased average daily gain of lambs, whereas treatments had no significant effect on feed intake. The pH values of meat were increased at 0.25% RPC and both, dripping loss and shear force of meat, were significantly decreased in RPC-supplemented lambs. No significant changes were observed for dressing percentage and intramuscular fat. RPC supplementations had no significant effect on the concentrations of triglycerides and cholesterols in serum, but the concentration of high-density lipoprotein was decreased at 0.50% RPC and that of low-density lipoprotein was increased at 0.75% RPC. In m. longissimus dorsi, the expressions of cluster of differentiation 36 (CD36), acetyl-CoA carboxylase (ACC) and fatty-acid synthase (FASN) genes were increased at 0.25% RPC. Supplementation of 0.75% RPC increased the expressions of lipoprotein lipase (LPL) and FASN genes, decreased the expression of ACC gene and had no effect on CD36 gene. The results of this study showed that supplementation of 0.25% RPC could promote growth performance of lambs and improve meat quality. This may be mediated by effects on blood lipid profiles and the metabolism of fatty acids in skeleton muscles. However, the beneficial effects of 0.25% RPC supplementation need to be validated with a larger number of animals. Higher doses, particularly 0.75% RPC, showed adverse effects on live weight gain and ACC expression.

Influence of rumen-protected choline on liver composition and blood variables indicating energy balance in periparturient dairy cows

Rumen-protected choline (RPC) was evaluated for effects on the lipid and glycogen content of the liver and metabolic variables in the blood plasma of dairy cows. Thirty-two Holstein cows were allocated into two groups (RPC group with RPC supplementation and control group without RPC supplementation) 28 days before the expected calving. Cows were fed the experimental diet from 21 days before calving until day 60 of lactation. The diet of the RPC group was supplemented with 100 g/day of RPC from 21 days prepartum until calving and 200 g/day of RPC for 60 days postpartum, providing 25 and 50 g of choline, respectively. Liver samples were taken by percutaneous needle biopsy, then analysed for total lipid (TLl), triglyceride (TGl) and glycogen (GLYl) contents on days -21, +7, +35 and +60 relative to calving. Blood was collected on the same sampling days and 21 days after calving. Glucose, non-esterified fatty acid (NEFA), β-hydroxybutyrate (BHBA), triglyceride (TGp), total cholesterol (TCh), urea, ammonia and aspartate aminotransferase (AST) were determined from blood samples. The TLl and TGl contents were 25.0 ± 4.3 g and 25.3 ± 3.8 g per kg wet weight (mean ± SEM), respectively, lower in the RPC group than in the control animals. No significant differences were observed in the GLYl concentrations between the two groups. However, a lower TGl: GLYl ratio was shown in the liver of cows fed the RPC diet as compared to the controls. RPC supplementation decreased BHBA while increasing TGp concentrations were shown in the blood of cows fed the RPC diet, possibly as a consequence of improved lipoprotein synthesis in, and triglyceride excretion from, the liver, together with a reduced rate of ketogenesis.

Folic acid in ruminant nutrition: a review

Folic acid plays an essential role in DNA and methionine metabolism. Micro-organisms in the rumen can synthesise folates, but it has not been verified that these amounts are sufficient to achieve the best efficiency of dairy cows. However, the amount of folates synthesised in the rumen could possibly, to some extent, be affected by the forage:concentrate ratio. Degradation of orally supplemented folic acid in the rumen seems to be very high (about 97 %), as supplementation of folic acid hardly increases folate concentrations in the digesta at the duodenum. However, it must be considered that dietary supplements of folic acid higher than 0·5 mg/kg body weight increased serum folate concentrations in all available studies and milk folate concentrations in most studies. Additionally, milk production tended to be increased in some studies. Therefore, degradation of folic acid in the rumen may be overestimated as folates can be absorbed at the proximal duodenum. For future research it is necessary to consider the whole flow and the metabolic pathways of folates from the rumen to duodenum, blood, tissue, milk and transfer to calf to declare requirement values for cows. Consequently, the present review discusses current knowledge and emphasises areas for future research.