Effects of Rumen-Protected Glutamate Supplementation during the Periparturient Period on Digestibility, Inflammation, Metabolic Responses and Performance in Dairy Cows
Creators: Hisadomi, Satoko
Publisher: name: University of Alberta Library
Year: 2022

<p>Dairy cows often experience negative energy balance, fat mobilization and inflammation after calving, which increases health problems. Glutamate (Glu) is a primary energy source for the small intestine and a glucogenic amino acid in the liver, and feeding Glu enhances gastrointestinal growth, barrier function, and digestive and absorptive capacity in monogastric animals. However, the effects of feeding Glu in dairy cows during the calving transition period have not been studied. The objective of this thesis was to evaluate the effects of feeding rumen-protected Glu during the periparturient period (d -21 ± 3 to d 21 ± 3 relative to calving) on apparent total-tract digestibility (ATTD), inflammation, metabolic responses, and production performance of dairy cows. Fifty-two multiparous Holstein cows were blocked by parity, body condition score, and expected calving date, and randomly assigned to one of the experimental diets with rumen-protected monosodium Glu (RP-Glu; intestinally available Glu = 8.8%) or without RP-Glu (control) at d -21 ± 3 relative to expected calving date. The RP-Glu was fed at 4% and 3% of dietary dry matter, before and after calving, respectively. Prepartum diets contained 17.1% and 16.5% crude protein, and 13.1% and 13.3% starch, and postpartum diets contained 18.8% and 18.3% crude protein, and 22.5% and 22.7% starch on a dry matter basis, respectively for RP-Glu and CON treatments. A subset of nineteen cows was used to measure ATTD. Cows fed the RP-Glu had greater ATTD of dry matter (70.6 vs. 69.1 %; P = 0.05), crude protein (75.1 vs. 72.6 %; P = 0.03), and ether extract (66.0 vs. 61.2 %; P = 0.05) on d 5 ± 1 after calving. Cows fed the RP-Glu also had greater dry matter intake (15.7 vs. 13.7 kg/d; P = 0.03) on d 1 after calving. Cows fed the RP-Glu had greater plasma concentrations of Glu (4.60 vs. 3.89 µmol/dL; P &lt; 0.01) and insulin-like growth factor-1 (44.2 vs. 30.1 ng/mL; P &lt; 0.01), lower serum concentrations of free fatty acids (670 vs. 981 µEq/L; P &lt; 0.01) and total bilirubin (0.22 vs. 0.34 mg/dL; P &lt; 0.01), and lower plasma 3-methylhistidine concentration (1.28 vs. 1.50 µmol/dL; P = 0.03) on d 4 after calving. However, these treatment effects observed between d 1 and d 5 ± 1 immediately after calving did not continue until d 21 after calving. Concentrations of serum amyloid A, serum haptoglobin, and plasma lipopolysaccharide binding protein were not affected by the treatment. In addition, no differences were observed for serum -hydroxybutyrate concentration and milk yield during the postpartum period between the two groups, and cows fed the RP-Glu decreased lactose yield. These results indicate that feeding RP-Glu during the periparturient period can increase digestive capacity and feed intake, and decrease body fat and protein mobilization immediately after calving without increasing milk production. Dietary Glu requirement is not established for dairy cows, however, our findings suggest that cows may not be able to synthesize sufficient Glu in the body immediately after calving.</p>