Effect of dietary N-carbamoylglutamate on milk production and nitrogen utilization in high-yielding dairy cows

Abstract

The objective of the current study was to investigate the effect of N-carbamoylglutamate (NCG) supplementation on milk production and nitrogen (N) utilization in Chinese Holstein dairy cows. Sixty multiparous cows (78±17.3 d in milk, 635±61.00kg of body weight, and 41.9±7.9kg/d milk yield; mean ± SD) were blocked by parity, days in milk, and milk yield and randomly allocated to 1 of 4 groups, each of which was fed a dietary treatment containing 0 (control), 10, 20, or 30g of NCG/d. Milk yield was recorded weekly. Dry matter intake, milk composition, plasma variables, and urea N contents in plasma, urine, and milk were determined every other week. Blood samples were collected from the coccygeal vein. Rumen microbial protein synthesis was estimated based on the purine derivatives in the urine. Dry matter intake was found to be similar between the treatments. Addition of 20g of NCG/d tended to increase milk yield (40.2 vs. 38.1kg/d) and increased the content (2.83 vs. 2.74%) and yield (1.12 vs. 1.02kg/d) of milk protein compared with the control. The yield and content of milk fat were similar between the treatments, whereas the contents of lactose and total solids increased linearly with an increase in NCG. Dietary supplementation of NCG linearly increased the plasma nitric oxide level and decreased the plasma ammonia N level. Compared with the control, the plasma Arg concentration in cows fed 10, 20, and 30g of NCG/d was increased by 1.1, 10.4, and 16.0%, respectively. The urea N concentrations in the milk, plasma, and urine decreased with the addition of NCG, although the lowest urea N concentrations were observed with the addition of 20g of NCG/d. The conversion of dietary crude protein to milk protein exhibited quadratic trends of improvement by NCG supplementation, with a peak at 20g of NCG/d. The rumen microbial protein synthesis was not altered by NCG supplementation, but the metabolizable protein tended to show a quadratic increase in cows fed 20g of NCG/d. In conclusion, supplementation of 20g of NVG/d may alter the plasma metabolites, optimize the AA profile, increase the metabolizable protein utilization, and thereby improve the lactation performance and N utilization of high-yielding dairy cows.

N-carbamylglutamate restores nitric oxide synthesis and attenuates high altitude-induced pulmonary hypertension in Holstein heifers ascended to high altitude

“…In Holstein cattle, dietary supplementation with NCG was shown to decrease plasma ammonia and urea concentrations [23]. In the present study, NCG supplementation decreased plasma ammonia concentrations, which suggests that NCG is a potent agent for accelerating ammonia reduction and arginine synthesis.…”

“…Physiological parameters were determined, and blood samples were collected after a 30-day adaptation period. Thereafter, heifers were individually supplemented with 20 g of NCG (Asia Pacific Xingmu Technology Co., Ltd., Beijing, China; 98% purity) per day [23] at 07:00 a.m. bytop-dressed feeding onto the total mixed ration (TMR, Additional file 1: Table S1). The physiological and blood parameters were determined after a 4-week feeding period.…”

“…The intra- and- inter- assay coefficients of variation were 6.0% and 11%, respectively. Plasma NO was measured using a commercial NO kit (Nanjing Jiancheng Bioengineering Research Institute, Nanjing, China) [23]. Plasma urea was measured using a urea analysis kit (ab83362; Abcam, Cambridge, UK), and ammonia was measured using an ammonia analysis kit (ab83362; Abcam, Cambridge, UK).…”

“…L -arginine, a substrate for eNOS [18], has been used to attenuate pulmonary hypertension in broiler chickens grown at high altitudes [19]. N-carbamylglutamate (NCG), which is a structural analog of N-acetylglutamate [20], promotes urea cycling, and increases the endogenous synthesis of arginine [21], eNOS [22], and NO [23]. Although the effects of L -arginine in increasing NO synthesis and eNOS expression, and attenuating pulmonary hypertension have been previously studied [19, 24], the effects of NCG on alleviating HAPH remain unknown.…”

N-carbamylglutamate and L-arginine improved maternal and placental development in underfed ewes

“…The doses of Arg were based on previous studies of pregnant sheep that received parenteral administration of Arg (Wu et al 2007, Lassala et al 2010, McCoard et al 2013, Satterfield et al 2013. The dose of NCG was based on previous studies on rats, piglets, and dairy cows (Wu et al 2012b, Zeng et al 2012, Chacher et al 2014. Nutrient restriction (50% NRC) was achieved by feeding one-half of the total complete diet calculated to meet 100% NRC requirements.…”