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

Abstract

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.

Feeding increasing amounts of ruminally protected choline decreased fatty liver in nonlactating, pregnant Holstein cows in negative energy status

“…In agreement with the current experiment, most laboratories have reported no effect of RPC ion supplementation on circulating concentrations of BHB in early postpartum dairy cows (Piepenbrink and Overton, 2003;Janovick Guretzky et al, 2006;Zahra et al, 2006;Zom et al, 2011;Zhou et al, 2016b) although Elek et al (2013) and Sun et al (2016) reported decreased concentration of plasma BHB in early lactation cows fed RPC ions, suggesting a possible decreased risk of subclinical ketosis. Clinical ketosis was decreased in primiparous and multiparous dairy cows fed RPC ions during the transition period on a commercial dairy farm (Lima et al, 2012).…”

“…The literature reporting the effect of supplementing RPC ions on the plasma concentration of cholesterol in early lactating dairy cows (cows in negative EB) is equivocal. Pinotti et al (2004) and Soltan et al (2012) reported an increase, Sun et al (2016) reported a decrease, and Pinotti et al (2003), Janovick Guretzky et al (2006), Zahra et al (2006), Elek et al (2013), and Zhou et al (2016a) reported no effect of supplemental RPC ions on plasma cholesterol. The effect of RPC ions on plasma cholesterol reported by Soltan et al (2012) and Sun et al (2016) were not changed when intake of methionine was altered.…”

“…Piepenbrink and Overton (2003) reported a linear increase in concentration of hepatic glycogen of multiparous Holstein cows at 1 and 21 DIM as intake of RPC ions increased from 0 to 9.7 to 12.9 to 16.1 g/d apart from any change in DMI. Likewise, hepatic glycogen was greater at 35 DIM if multiparous cows were fed RPC ions at 19 and 37 g/d prepartum and postpartum, respectively, without a change in DMI (Elek et al, 2013). Increased concentration of hepatic glycogen may result from increased synthesis of glucose and from sparing of glycogen from hydrolysis.…”

“…This may have been partly due to a greater intake of metabolizable methionine in the current experiment during feed restriction possibly allowing greater synthesis of PC from PE in the liver diluting the effect of supplemental RPC ions. Multiparous Holstein cows in early lactation also have experienced a lower concentration of hepatic TAG to RPC ion supplementation (Santos and Lima, 2009;Zom et al, 2011;Elek et al, 2013), although Zahra et al (2006), Zhou et al (2016b), and reported no decrease in hepatic TAG. Supplemental choline ions may allow the liver to synthesize more PC, a necessary and major component of VLDL molecules which are required for hepatic export of TAG.…”

“…However, treating primary hepatocytes from neonatal Holstein calves with increasing concentrations of choline chloride (0, 61, 128, 2,028, and 4,528 µmol/L) increased the secretion of VLDL in the medium (Chandler and White, 2017). The supplementation of ruminally protected choline (RPC) ions to periparturient dairy cows (from approximately 21 d before calving through at least 21 d postpartum) decreased the postpartum concentration of hepatic TAG in some (Santos and Lima, 2009;Zom et al, 2011;Elek et al, 2013) but not in other experiments (Zahra et al, 2006;Zhou et al, 2016b;. The source (ReaShure, Balchem Corp., New Hampton, NY) and amount of RPC ions fed (approximately 12.9 g/d) were the same across these studies with the exception of Elek et al (2013) who fed 18.6 g/d prepartum and 37.3 g/d postpartum of RPC ions from a different commercial source Nordos,Bussolengo,Italy).…”