The effect of fatty acids and starvation on the metabolism of gluconeogenic precursors by isolated sheep liver cells

Lomax, M.A.; Donaldson, Iain A.; Pogson, Christopher I.

doi:10.1042/bj2400277

Cited by 11 publications

(8 citation statements)

References 27 publications

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“…It has been suggested that fasting periods are not a confounding factor when determining glucose curve concentrations in adult ruminants (Kaneko, 2008) due to limited intestinal glucose absorption (Reynolds et al, 1988). In vitro studies conducted in sheep have shown that liver cells derived from fed animals had higher glucose synthesis rates than cells cultured from fasted animals (Lomax et al, 1986). The results from our study demonstrate that basal glucose concentrations are affected by the length of fasting period, predominantly at 24, 36, and 48 h. On the other hand, similar glucose concentrations were found when 12-h food-deprived females were compared with animals without feed restriction, which might be attributed to the effects of rumen content on nutrient availability.…”

Section: Discussionmentioning

confidence: 99%

Influence of food deprivation on intravenous glucose tolerance test traits in Holstein Friesian heifers

González-Grajales

Pieper

Kremer

et al. 2017

Journal of Dairy Science

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Glucose is essential for numerous cellular functions due to its involvement in energy supply from early development to adulthood. In the lactating cow, glucose demands by the mammary gland significantly increase to support milk production when compared with other tissues. Thus, insufficient blood glucose levels might predispose dairy cows to metabolic disturbances. The intravenous glucose tolerance test (ivGTT) is a suitable tool to characterize glucose metabolism and insulin responses, but results must be reliable and repeatable. One factor influencing ivGTT is food deprivation period, which has been considered as an obligatory requirement before conduction of glucose tolerance studies in monogastric species, whereas it has been permissive in ruminants. The objective of this study was to determine the influence of 5 fasting periods (0, 12, 24, 36, and 48 h) on ivGTT traits and insulin responses in German Holstein heifers. A total of 140 tests were conducted in 28 females aged 12 to 19 mo. Blood samples were collected every 7 min within 1 h. Assessed glucose and insulin parameters included basal serum glucose and insulin concentration, maximum glucose and insulin concentration obtained between min 7 to 21, and concentrations at min 63 (last sampling) relative to glucose administration, glucose area equivalent (GA), glucose area under the curve (GAUC), insulin area equivalent (InsA), insulin area under the curve (InsAUC), and blood glucose half-life time (GHLT). Serum glucose and insulin concentration were measured according to the hexokinase colorimetric method and solid phase radio immunoassay, respectively. The generalized linear mixed model was used to test for significant differences in all glucose traits and insulin responses at different fasting periods. The model used season and weight as confounding variables. Glucose and insulin concentrations at 0, 7 to 21 (maximum concentration), and 63 min were affected by the duration of food deprivation. The GA, InsA, GAUC, InsAUC, and especially GHLT were also affected by fasting period. A positive linear relationship between GHLT and length of food deprivation was found. Significantly higher GA, GAUC, GHLT values, and glucose and insulin concentration at min 63 were obtained at increasing fasting periods. High intraclass correlation coefficient (0.48) was found for GHLT. The results demonstrate that GHLT might be used to reliably characterize an individual's glucose metabolism and the importance of standardizing food deprivation schedules when performing an ivGTT in nongestating Holstein heifers.

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Section: Discussionmentioning

confidence: 99%

Influence of food deprivation on intravenous glucose tolerance test traits in Holstein Friesian heifers

González-Grajales

Pieper

Kremer

et al. 2017

Journal of Dairy Science

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“…Their contribution varies with the balance between availability in gluconeogenic precursors, whole body glucose demand and utilization as well as whole body AA demand (Kraft, 2009). During body store mobilization as in feed restriction or lactation, contribution of endogenous precursors (in particular AAs from muscle proteolysis) increases (Lomax et al, 1986). It is also the case when glucose demand increases, such as after phlorizin treatment of lactating cows (Overton et al, 1999).…”

Section: Metabolism Of Vfa and Glucose By Portal-drained Visceramentioning

confidence: 98%

Carbohydrate quantitative digestion and absorption in ruminants: from feed starch and fibre to nutrients available for tissues

Nozière

Ortigues-Marty

Loncke

et al. 2010

Animal

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Carbohydrates are the main source of energy in ruminants. Their site, extent and kinetics of digestion highly impact the amount and profile of nutrients delivered to peripheral tissues, and the responses of the animal, i.e. ingestion, efficiency of production, N and methane excretion, quality of products and welfare. Development of multi-objective feed evaluation systems thus requires a more integrated quantitative knowledge on carbohydrate digestion and yield of terminal products, as well as on their metabolism by splanchnic tissues. The objective of this paper is to review (i) quantitative knowledge on fibre, starch and sugar digestion, volatile fatty acids (VFA) and glucose production and splanchnic metabolism and (ii) modelling approaches which aim at representing and/or predicting nutrient fluxes in the digestive tract, portal and hepatic drainage. It shows that the representation of carbohydrate digestion and VFA yield is relatively homogeneous among models. Although published quantitative comparisons of these models are scarce, they stress that prediction of fibre digestion and VFA yield and composition is still not good enough for use in feed formulation, whereas prediction of microbial N yield and ruminal starch digestion seems to be more satisfactory. Uncertainties on VFA stoichiometric coefficients and absorption rates may partly explain the poor predictions of VFA. Hardly any mechanistic models have been developed on portal-drained viscera (PDV) metabolism whereas a few exist for liver metabolism. A qualitative comparison of these models is presented. Most are focused on dairy cows and their level of aggregation in the representation of nutrient fluxes and metabolism highly differs depending on their objectives. Quantitative comparison of these models is still lacking. However, recent advances have been achieved with the empirical prediction of VFA and glucose production and fluxes through PDV and liver based on the current INRA feed evaluation system. These advances are presented. They illustrate that empirical prediction of ruminal VFA and intestinal glucose production can be evaluated by comparison with measured net portal net fluxes. We also illustrate the potential synergy between empirical and mechanistic modelling. It is concluded that concomitant empirical and mechanistic approach may likely help to progress towards development of multi-objective feed evaluation systems based on nutrient fluxes.

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“…Following a 16-h fast, they found circulating glucose concentrations of neonatal rats injected with glucogenic substrates to increase 2-fold (from 1.1 to 2.6 mM), whereas a similar injection into rats previously fed triglycerides increased blood glucose 4-fold (from 1.1 to 4.7 mM; Ferre et al, 1978). Based on in vitro work with sheep hepatocytes, Lomax et al (1986) proposed that reducing equivalents from fatty acid metabolism affect the transport of carbon atoms across the mitochondrial membrane. This is of particular importance when shuttling malate carbon during gluconeogenesis in the transition dairy cow.…”

Section: Introductionmentioning

confidence: 99%

Effects of Feeding Propionate and Calcium Salts of Long-Chain Fatty Acids on Transition Dairy Cow Performance

DeFrain

Hippen

Kalscheur

et al. 2005

Journal of Dairy Science

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Multiparous Holstein cows (n = 40) were used in a randomized complete block design to determine the effects of feeding Ca and Na salts (1:1, wt/wt) of propionate and Ca salts of long-chain fatty acids (LCFA) on transition cow performance. All cows were fed the same basal diet once daily for ad libitum intake. Treatments (g/d) were 320 cornstarch (CS) as a control, 120 propionate (PRO), 120 propionate and 93 LCFA (PF1), and 178 propionate and 154 LCFA (PF2). Treatments were hand-mixed into the upper one-third of the TMR from 2 wk pre- through 3 wk postpartum. Intakes were recorded from 21 d pre- through 21 d postpartum. Energy density and crude protein were 1.54 and 1.65 Mcal/kg and 14.4 and 18.8% for pre- and postpartum diets, respectively. All cows received a common diet from 22 to 70 days in milk (DIM). Milk composition was analyzed on d 7, 14, and 21. Blood was sampled at 14, 7, and 2 d prepartum and 2, 7, 14, and 21 DIM. Pre- and postpartal dry matter intake (DMI) averaged 11.9 and 16.4 kg/d, respectively, and did not differ among treatments. A diet x week interaction for postpartal DMI was observed as cows fed PF2 consumed 2 kg/d less DM during wk 2 relative to other treatments. Milk yields from 22 to 70 DIM were 48.8, 48.5, 47.8, and 51.3 kg/d for CS, PRO, PF1, and PF2, respectively, and were not significantly affected by treatments. Milk true protein (3.32 vs. 3.16%) was increased and MUN (12.5 vs. 14.4 mg/dL) was decreased for CS relative to other treatments. Milk fat yield from cows fed PRO tended to be greater than those fed PF1 (1.58 vs. 1.29 kg/d). Plasma glucose, insulin, and beta-hydroxybutyrate were not affected by treatments. The PF2 treatment tended to decrease NEFA in plasma relative to PF1 over all times measured (492 and 670 muEq/L) and significantly decreased plasma NEFA relative to those fed PF1 postpartum (623 and 875 muEq/L). Relative to PF1, feeding propionate and LCFA at the higher level in this experiment improved energy balance postpartum as evidenced by decreased concentrations of plasma NEFA.

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The effect of fatty acids and starvation on the metabolism of gluconeogenic precursors by isolated sheep liver cells

Cited by 11 publications

References 27 publications

Influence of food deprivation on intravenous glucose tolerance test traits in Holstein Friesian heifers

Influence of food deprivation on intravenous glucose tolerance test traits in Holstein Friesian heifers

Carbohydrate quantitative digestion and absorption in ruminants: from feed starch and fibre to nutrients available for tissues

Effects of Feeding Propionate and Calcium Salts of Long-Chain Fatty Acids on Transition Dairy Cow Performance

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