Rumen-protected choline reduces hepatic lipidosis by increasing hepatic triacylglycerol-rich lipoprotein secretion in dairy cows

Impact of replacing protein pellets with soybean grain on nutrient utilization and the rumen and blood parameters of feedlot cattle under tropical conditions

The aim of this study was to explore the effect of replacing protein pellets with soybean grain in high-concentrate diets with or without the addition of silage, on the intake, digestibility, and rumen and blood parameters of feedlot cattle in tropical regions. Four cannulated, crossbred steers were used, 4.5 ± 0.5 years old, with an average weight of 685.55 ± 111.78 kg. The steers were distributed in a 4 × 4 Latin square, in a 2 × 2 factorial scheme (two sources of protein: protein pellets or whole soybean grain, with or without added dietary bulk). There was no effect (P ≥ 0.109) from the interaction between the source of protein and the addition of silage to the diet on dry matter (DM) and nutrient intake, or the digestibility (P ≥ 0.625) of DM or crude protein (CP). However, both factors affected (P ≤ 0.052) the intake of DM, neutral detergent fiber (NDF), and non-fiber carbohydrates (NFC), as well as the independent digestibility (P ≤ 0.099) of fat, NFC, total carbohydrates (TC), and total cholesterol concentration. There was an effect (P ≤ 0.053) from the interaction between the source of protein and the addition of silage to the diet on the digestibility of NDF and total digestible nutrients (TDN), as well as on the glycose concentration (P = 0.003). Blood parameters (i.e. protein, albumin, creatinine, triglycerides, aspartate aminotransferase (AST), and alanine aminotransferase (ALT)) were not affected (P ≥ 0.139) by the source of protein, the addition of silage, or their interaction. Lastly, including 150 g/kg silage DM in a high-grain diet, and using soybean grain as a source of protein in substitution of protein pellet could be a suitable nutritional strategy to ensure adequate DM and nutrient intake and digestibility, with no detrimental effects on rumen and blood parameters of feedlot cattle in the tropics.

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.

Effect of rumen-protected choline on fat digestibility and lymph metabolome in dairy cows

Objectives were to determine the effects of supplementing rumen-protected choline (RPC) from an established source with low (L, 28.8%) or a prototype with less lipid coating protection and high (H, 60.0%) concentrations of choline chloride on digestibility of fat and supra-mammary lymph metabolome in feed-restricted cows. Pregnant, nonlactating Holstein cows (n = 33; 11/treatment) at mean (±standard deviation) 231 ± 4.7 days of gestation were blocked by body condition (4.23 ± 0.47) and assigned to receive 0 (CON) or 25.8 g/d of choline ion from L (L25.8) or H (H25.8). Cows were adapted to the diet and then fed-restricted to 42% of the net energy of lactation required for maintenance and pregnancy for 9 days. Intake of metabolizable methionine was maintained at 19 g/d. On Day 9, cows were fed 450 g of saturated fatty acids (SFA), and feces and blood were sampled continuously for 24 h. Supra-mammary lymph was sampled 6 h after feeding SFA and metabolome was characterized. Feeding RPC increased digestibility of fat (CON = 80.4 vs. RPC = 86.0 ± 1.9%) and reduced the concentration of haptoglobin in serum (CON = 174 vs. RPC = 77 ± 14 µg/ml) independent of source of RPC fed. Feeding RPC increased the concentrations of triacylglycerol in serum (CON = 15.1 vs. RPC = 17.8 ± 1.9 mg/dl) in feed-restricted cows after feeding SFA, and the increment tended to be greater for cows fed H25.8 than L25.8. Supplementing RPC tended to increase the concentrations of triacylglycerol (CON = 11.4 vs. RPC = 15.8 ± 3.4 mg/dl) in supra-mammary lymph. Feeding RPC increased the concentration of choline and affected the concentrations of analytes involved in metabolic pathways associated with amino acid metabolism and biosynthesis of phospholipids in lymph compared with CON. Feeding RPC, independent of source used, increased fat digestibility with some changes in lymph metabolome in cows under negative nutrient balance.

Influence of supplemental choline on milk yield, fatty acid profile, and weight changes in postpartum ewes and their offspring

Background and Aim

The most intensive nutritional requirements occur during milk production's peak. Ewe milk contains more protein and fat than cow milk. The nutritional factors significantly determine the composition. The liver undergoes high stress during lactation but is relieved by essential nutrients. Choline acts metabolically as a lipotrope. This compound functions in cell structure construction, maintenance, and acetylcholine synthesis. The animal nutrition industry provides choline from various sources, such as synthetic and natural kinds. This study evaluated the influence of two distinct choline sources on dairy ewes' peripartum and postpartum milk production, composition, and offspring growth.

Materials and Methods

Twenty-four Rambouillet ewes, each weighing around 63.7 ± 1.7 kg, aged three with two previous births, spent 30-day pre-partum and post-partum in individual pens (2 × 2 m). They were given different experimental treatments 30 days before and after birth according to a randomized design; no choline (a), 4 g/day rumen-protected choline (RPC) (b), or 4 g/day thiocholine (c). Milk samples for milk composition and long-chain fatty acid (FA) analysis were taken every 30 days during milk collection.

Results

Significant differences (p < 0.05) in ewe body weight, lamb birth weight, and 30-day-old lamb body weight were observed at lambing and on day 30 of lactation due to choline treatment. Milk yield was significantly higher (1.57 kg/day) compared to the control (1.02 kg/day) and RPC (1.39 kg/day), due to the herbal choline source. There was no significant difference in the milk's protein, lactose, fat, non-fat solids, and total milk solids content between the treatments. Herbal choline lowers (p < 0.05) the concentrations of caproic, caprylic, capric, lauric, and myristic acids while boosting (p < 0.05) those of oleic and cis-11-eicosenoic acid, the changes influencing long-chain FA levels (p < 0.05).

Conclusion

Providing choline from both sources to ewes enhanced milk production and body weight at lambing and on 30-day post-lambing. The herbal choline supplement altered short-chain milk FAs, while representative concentration pathways affected medium-chain ones.

Rumen-Protected Choline Improves Metabolism and Lactation Performance in Dairy Cows

Choline is required for the synthesis of phosphatidylcholine, an important constituent of lipoproteins. Early lactation cows presumably synthesize insufficient phosphatidylcholine, and choline supplementation in a rumen-protected form might benefit metabolism and lactation. The objectives of this study were to determine the effects of feeding rumen-protected choline (RPC) on lactation and metabolism in dairy cows. In experiment 1, 369 nulliparous and parous Holstein cows housed in four pens per treatment were fed 12.9 g/day of choline as RPC from 25 days prepartum until 80 days postpartum. In experiment 2, 578 nulliparous cows housed in five pens/treatment were fed 12.9 g/day of choline as RPC in the last 22 days of gestation only. In both experiments, blood was sampled and analyzed for concentrations of nonesterified fatty acids (NEFAs) and glucose at 1, 14, and 21 days postpartum and of choline at 1 and 14 days postpartum. Blood from all cows was sampled and analyzed for concentrations of β-OH butyrate (BHB) at 1 and 14 days postpartum. Cows with BHB > 1.2 mmol/L were classified as having hyperketonemia. Hepatic tissue was collected from 46 cows from the eight pens in experiment 1 at 9 days postpartum and analyzed for concentrations of glycogen and triacylglycerol. Milk yield and components were measured for 80 days postpartum in experiment 1, whereas only milk yield was measured in experiment 2. The pen was the experimental unit of analysis. Supplementing RPC tended to increase dry matter intake (DMI) prepartum in experiments 1 and 2 and postpartum in experiment 1. Feeding cows with RPC increased yields of 3.5% fat-corrected milk (42.8 vs. 44.8 kg/day), energy-corrected milk (38.5 vs. 40.3 kg/day), milk fat (1.52 vs. 1.61 kg/day), and true protein (1.16 vs. 1.21 kg/day) in experiment 1. Milk yield tended to be greater with RPC (26.4 vs. 27.4 kg/day) in experiment 2. Supplementing RPC increased plasma choline concentrations on day 14 postpartum in experiment 1 (3.32 ± 0.27 vs. 4.34 ± 0.28 µM) and on day 1 in experiment 2 (3.35 ± 0.16 and 13.73 ± 0.15 µM). Treatment did not affect the concentrations of glucose, NEFAs, or BHB in plasma, but the incidence of hyperketonemia was less in multiparous cows fed RPC than those fed the control in experiment 1. Feeding cows with RPC reduced hepatic triacylglycerol content and tended to reduce the ratio of triacylglycerol to glycogen and the risk of hepatic lipidosis in cows in experiment 1. The concentrations of hepatic triacylglycerol on day 9 postpartum were inversely related to those of choline in plasma on day 1 postpartum. Feeding cows with RPC improved lactation and metabolism, but more benefits were noted when it was fed before and after calving.

Characterization of a model to induce hyperlipidemia in feed-restricted dairy cows

Hepatic lipidosis is a prevalent metabolic disorder, and in vivo models to study intermediary lipid metabolism are needed in dairy cows. Objectives were to apply a method to induce hyperlipidemia and characterize the responses and safety of the intervention in feed-restricted dry Holstein cows at 8 mo of gestation. It was hypothesized that infusion of tyloxapol would induce hyperlipidemia without deleterious effects on health of dairy cows. Pregnant, nonlactating parous Holstein cows (n = 33) at a mean (± standard deviation) of 234 ± 2.2 d of gestation were fed for ad libitum intake on d 1 to 5 and restricted to 41% of the required NEL from d 6 to 13. On d 14, when cows were 247 ± 2.2 d of gestation, cows were kept off feed, and received i.v. a 10% solution of tyloxapol at 120 mg/kg body weight to block hydrolysis of triacylglycerols in very-low-density lipoprotein (VLDL) particles. Blood was sampled for 720 min and analyzed for concentrations of triacylglycerol, VLDL cholesterol, and total cholesterol in serum to reflect hepatic secretion or reduced clearance of such metabolites from blood. Rectal temperature, respiration and heart rates, and clinical signs related to potential anaphylaxis were monitored for the first 30 min relative to tyloxapol infusion, and for any abnormal behavior in the subsequent 24 h. Infusion of tyloxapol progressively increased the concentrations of triacylglycerol, VLDL cholesterol, and total cholesterol in serum. Tyloxapol increased rectal temperature by 0.19°C at 30 min after infusion and increased respiration and heart rates in the first 10 min after infusion by 29% and 40%, respectively. Tyloxapol induced tachycardia (heart rate >80 beats/min) in 66.7% (n = 22), frothy salivation in 39.4% (n = 13), muzzle twitching in 15.2% (n = 5), eyes twitching in 12.1% (n = 4), muscle twitching in 48.5% (n = 16), nystagmus in 6.1% (n = 2), signs of hyperexcitement in 18.2% (n = 6), staggering gait in 18.2% (n = 6), and anaphylaxis in 12.1% (n = 4) of the cows; however, all these signs were transient, and cows returned to normal after 20 min of infusion. No other abnormal behavior was observed past 20 min of tyloxapol infusion. None of the cows aborted and gestation length, calf birth weight, and risk of diseases in the first 21 d postpartum did not differ between cows receiving tyloxapol and a companion group that did not receive tyloxapol. Infusion of tyloxapol induced hyperlipidemia in cows with some animals showing transient reactions to the treatment, but without complications to the cow and the offspring. Application of this model can be useful to study intermediary lipid metabolism in dairy cows.

Enhancing Metabolism and Milk Production Performance in Periparturient Dairy Cattle through Rumen-Protected Methionine and Choline Supplementation

For dairy cattle to perform well throughout and following lactations, precise dietary control during the periparturient phase is crucial. The primary issues experienced by periparturient dairy cows include issues like decreased dry matter intake (DMI), a negative energy balance, higher levels of non-esterified fatty acids (NEFA), and the ensuing inferior milk output. Dairy cattle have always been fed a diet high in crude protein (CP) to produce the most milk possible. Despite the vital function that dairy cows play in the conversion of dietary CP into milk, a sizeable percentage of nitrogen is inevitably expelled, which raises serious environmental concerns. To reduce nitrogen emissions and their production, lactating dairy cows must receive less CP supplementation. Supplementing dairy cattle with rumen-protected methionine (RPM) and choline (RPC) has proven to be a successful method for improving their ability to use nitrogen, regulate their metabolism, and produce milk. The detrimental effects of low dietary protein consumption on the milk yield, protein yield, and dry matter intake may be mitigated by these nutritional treatments. In metabolic activities like the synthesis of sulfur-containing amino acids and methylation reactions, RPM and RPC are crucial players. Methionine, a limiting amino acid, affects the production of milk protein and the success of lactation in general. According to the existing data in the literature, methionine supplementation has a favorable impact on the pathways that produce milk. Similarly, choline is essential for DNA methylation, cell membrane stability, and lipid metabolism. Furthermore, RPC supplementation during the transition phase improves dry matter intake, postpartum milk yield, and fat-corrected milk (FCM) production. This review provides comprehensive insights into the roles of RPM and RPC in optimizing nitrogen utilization, metabolism, and enhancing milk production performance in periparturient dairy cattle, offering valuable strategies for sustainable dairy farming practices.