Effects of increasing levels of whole Black Soldier Fly (Hermetia illucens) larvae in broiler rations on acceptance, nutrient and energy intakes and utilization, and growth performance of broilers.

Meal of black soldier fly larvae (BSFL), which requires extraction of protein and fat, is a novel protein source for poultry, while unprocessed whole BSFL could even directly be fed to chickens. Newly hatched Ross-308 chicks (n = 252) received whole BSFL at 10% (L10), 20% (L20), or 30% (L30) of voluntary feed intake (FI) of control chickens (CON) that received no BSFL but only age-specific diets (n = 63 birds / group) for 42 days (d). Acceptance and nutrient and energy intake of birds by BSFL and FI were calculated. Plasma metabolites were measured using an automatic enzymatic analyzer and immunoglobulins with ELISA. Depending on the variable, data were analyzed using ANOVA or repeated measures ANOVA to address treatment, time and interaction effects. Birds consumed all offered larvae. With the exception of d1, time spent by birds eating their daily portion of larvae (TSL, min/pen) did not differ among the larvae supply groups (P = 0.982). The L10 had a higher larvae eating rate (LER) that is, speed of larvae intake than did L20 and L30 (P < 0.05), implying increased competition for less available BSFL. The ratio of LER to feed eating rate (FER) was greater than 50 fold change difference (FCD), indicating a strong interest of chickens in BSFL over regular feed. Whole BSFL intake up to 30% of voluntary FI did not adversely affect broiler growth (P > 0.05). The L30 had lower total dry matter and metabolizable energy intakes (P < 0.05), although total fat intake was higher in L30 than in CON (P < 0.05). Compared with CON, 30% whole BSFL increased dietary protein-to-energy ratios, plasma uric acid and serum alkaline phosphatase concentrations (P < 0.05). We conclude that whole BSFL can be included in broiler rations up to 20% without negatively affecting growth performance and nutrient conversion efficiency, whereas a higher proportion is associated with lower protein utilization efficiency, possibly due to lower total energy intake.

Expression of specific signaling components related to muscle protein turnover and of branched-chain amino acid catabolic enzymes in muscle and adipose tissue of preterm and term calves.

Postnatal metabolism depends on maturation of key metabolic pathways around birth. In this regard, endogenous glucose production is impaired in calves born preterm. Concerning protein metabolism, the rates of protein turnover are greater during the neonatal period than at any other period of postnatal life. The mammalian target of rapamycin (mTOR) and the ubiquitin-proteasome system (UPS) are considered as the major regulators of cellular protein turnover. The objectives of this study were to investigate (1) the changes in plasma AA profiles, (2) the mRNA abundance of mTOR signaling and UPS-related genes in skeletal muscle, and (3) the mRNA abundance of branched-chain AA (BCAA) catabolic enzymes in skeletal muscle and adipose tissue in neonatal calves with different degree of maturation during the transition to extrauterine life. Calves (n = 7/treatment) were born either preterm (PT; delivered by cesarean section 9 d before term) or at term (T; spontaneous vaginal delivery) and were left unfed for 1 d. Calves in treatment TC were also spontaneously born but were fed colostrum and transition milk for 4 d. Blood samples were collected from all calves at birth and at 24 h of life. Additional blood samples were taken 2 h after feeding (26 h of life) for PT and T calves, and on d 4 of life for TC, to determine plasma glucose, urea, and AA. Tissue samples from 3 muscles [M. longissimus dorsi (MLD), M. semitendinosus (MST), and M. masseter (MM)], and kidney fat were collected following euthanasia at 26 h after birth (PT, T) or on d 4 of life (TC) at 2 h after feeding. The concentrations of the majority of plasma AA (Ala, Gln, Asn, Cit, Lys, Orn, Thr, and Tyr), nonessential AA, and total AA were greater during the first 24 h and also before and 2 h after feeding in PT than in T. The ratio of plasma BCAA to the aromatic AA (Tyr and Phe) was greatest in TC, followed by T, and least in PT. The mRNA abundance of mTOR and ribosomal protein S6 kinase 1 (S6K1) in MLD and MM was greater in PT and T than in TC. The mRNA abundance of muscle-specific ligases FBXO32 (F-box only protein 32) in the 3 different skeletal muscles and TRIM63 (tripartite motif containing 63) in MLD was greater in PT and T than in TC; in MM, TRIM63 mRNA was greatest in PT. The mRNA for BCKDHA and BCKDHB (the α and ß polypeptide of branched-chain α-keto acid dehydrogenase) in kidney fat was elevated in PT and T compared with TC, suggesting a possible enhancement of BCAA oxidation as energy source to cover the energetic and nutritional postnatal demands in PT and T in a starved state. The increased abundances of mTOR-associated signaling factors and muscle-specific ligase mRNA indicate a greater rate of protein turnover in muscles of PT and T in a starved state. Elevated plasma concentrations of several AA may result from enhanced muscle proteolysis and impaired conversion to glucose in the liver of PT calves.

Effect of maternal supplementation with essential fatty acids and conjugated linoleic acid on metabolic and endocrine development in neonatal calves.

We tested the hypothesis that the maternal supply of essential fatty acids (EFA), especially α-linolenic acid, and conjugated linoleic acid (CLA), affects glucose metabolism, the endocrine regulation of energy metabolism and growth, and the intestinal development of neonatal calves. We studied calves from dams that received an abomasal infusion of 76 g/d coconut oil (CTRL; n = 9), 78 g/d linseed oil and 4 g/d safflower oil (EFA; n = 9), 38 g/d Lutalin (BASF SE) containing 27% cis-9,trans-11 and trans-10,cis-12 CLA (CLA; n = 9), or a combination of EFA and CLA (EFA+CLA; n = 11) during the last 63 d of gestation and early lactation. Calves received colostrum and transition milk from their own dam for the first 5 d of life. Insulin-like growth factor (IGF)-I, leptin, and adiponectin concentrations were measured in milk. Blood samples were taken before first colostrum intake, 24 h after birth, and from d 3 to 5 of life before morning feeding to measure metabolic and endocrine traits in plasma. On d 3 of life, energy expenditure was evaluated by a bolus injection of NaH13CO3 and determination of CO2 appearance rate. On d 4, additional blood samples were taken to evaluate glucose first-pass uptake and 13CO2 enrichment after [13C6]-glucose feeding and intravenous [6,6-2H2]-glucose bolus injection, as well as postprandial changes in glucose, nonesterified fatty acids (NEFA), insulin, and glucagon. On d 5, calves were killed 2 h after feeding and samples of small intestinal mucosa were taken for histomorphometric measurements. The concentrations of IGF-I, adiponectin, and leptin in milk decreased during early lactation in all groups, and the concentrations of leptin in first colostrum was higher in EFA than in CTRL cows. Plasma glucose concentration before first colostrum intake was higher in EFA calves than in non-EFA calves and was lower in CLA calves than in non-CLA calves. Plasma IGF-I concentration was higher on d 1 before colostrum intake in EFA calves than in EFA+CLA calves and indicated an overall CLA effect, with lower plasma IGF-I in CLA than in non-CLA calves. Postprandial NEFA concentration was lowest in EFA and CLA calves. The postprandial rise in plasma insulin was higher in EFA than in non-EFA calves. Plasma adiponectin concentration increased from d 1 to d 2 in all groups and was higher on d 3 in CLA than in non-CLA calves. Plasma leptin concentration was higher on d 4 and 5 in EFA than in non-EFA calves. Maternal fatty acid treatment did not affect energy expenditure and first-pass glucose uptake, but glucose uptake on d 4 was faster in EFA than in non-EFA calves. Crypt depth was lower, and the ratio of villus height to crypt depth was higher in the ilea of CLA than non-CLA calves. Elevated plasma glucose and IGF-I in EFA calves immediately after birth may indicate an improved energetic status in calves when dams are supplemented with EFA. Maternal EFA and CLA supplementation influenced postprandial metabolic changes and affected factors related to the neonatal insulin response.

Modulation of colostrum composition and fatty acid status in neonatal calves by maternal supplementation with essential fatty acids and conjugated linoleic acid starting in late lactation.

Sufficient maternal supply of essential fatty acids (EFA) to neonatal calves is critical for calf development. In the modern dairy cow, EFA supply has shifted from α-linolenic acid (ALA) to linoleic acid (LA) due to the replacement of pasture feeding by corn silage-based diets. As a consequence of reduced pasture feeding, conjugated linoleic acid (CLA) provision by rumen biohydrogenation was also reduced. The present study investigated the fatty acid (FA) status and performance of neonatal calves descended from dams receiving corn silage-based diets and random supplementation of either 76 g/d coconut oil (CTRL; n = 9), 78 g/d linseed oil and 4 g/d safflower oil (EFA; n-6/n-3 FA ratio = 1:3; n = 9), 38 g/d Lutalin (BASF SE, Ludwigshafen, Germany) providing 27% cis-9,trans-11 and trans-10,cis-12 CLA, respectively (CLA; n = 9), or a combination of EFA and CLA (EFA+CLA; n = 11) in the last 9 wk before parturition and following lactation. The experimental period comprised the first 5 d of life, during which calves received colostrum and transition milk from their own dam. The nutrient compositions of colostrum and transition milk were analyzed. Plasma samples were taken after birth and before first colostrum intake and on d 5 of life for FA analyses of the total plasma fat and lipid fractions. Maternal EFA and CLA supplementation partly affected colostrum and transition milk composition but did not change the body weights of calves. Most EFA in calves were found in the phospholipid (PL) and cholesterol ester (CE) fractions of the plasma fat. Maternal EFA supplementation increased the percentage of ALA in all lipid fractions of EFA and EFA+CLA compared with CTRL and CLA calves on d 1 and 5, and the increase was much greater on d 5 than on d 1. The LA concentration increased from d 1 to 5 in the plasma fat and lipid fractions of all groups. The concentrations of docosapentaenoic acid, docosahexaenoic acid, and arachidonic acid in plasma fat were higher on d 1 than on d 5, and the percentage of n-3 metabolites was mainly increased in PL if dams received EFA. The percentage of cis-9,trans-11 CLA was higher in the plasma fat of EFA+CLA than CTRL calves after birth. By d 5, the percentages of both CLA isomers increased, leading to higher proportions in plasma fat of CLA and EFA+CLA than in CTRL and EFA calves. Elevated cis-9,trans-11 CLA enrichment was observed on d 5 in PL, CE, and triglycerides of CLA-treated calves, whereas trans-10,cis-12 CLA could not be detected in individual plasma fractions. These results suggest that an altered maternal EFA and CLA supply can reach the calf via the placenta and particularly via the intake of colostrum and transition milk, whereas the n-3 and n-6 FA metabolites partly indicated a greater transfer via the placenta. Furthermore, the nutrient supply via colostrum and transition milk might be partly modulated by an altered maternal EFA and CLA supply but without consequences on calf performance during the first 5 d of life.

Glucose metabolism and the somatotropic axis in dairy cows after abomasal infusion of essential fatty acids together with conjugated linoleic acid during late gestation and early lactation.

Sufficient glucose availability is crucial for exploiting the genetic potential of milk production during early lactation, and endocrine changes are mainly related to repartitioning of nutrient supplies toward the mammary gland. Long-chain fatty acids, such as essential fatty acids (EFA) and conjugated linoleic acid (CLA), have the potential to improve negative energy balance and modify endocrine changes. In the present study, the hypothesis that combined CLA and EFA treatment supports glucose metabolism around the time of calving and stimulates insulin action and the somatotropic axis in cows in an additive manner was tested. Rumen-cannulated German Holstein cows (n = 40) were investigated from wk 9 antepartum (AP) until wk 9 postpartum (PP). The cows were abomasally supplemented with coconut oil (CTRL, 76 g/d); 78 g/d of linseed and 4 g/d of safflower oil (EFA); Lutalin (CLA, isomers cis-9,trans-11 and trans-10,cis-12 CLA, each 10 g/d); or the combination of EFA+CLA. Blood samples were collected several times AP and PP to determine the concentrations of plasma metabolites and hormones related to glucose metabolism and the somatotropic axis. Liver tissue samples were collected several days AP and PP to measure glycogen concentration and the mRNA abundance of genes related to gluconeogenesis and the somatotropic axis. On d 28 AP and 21 PP, endogenous glucose production (eGP) and glucose oxidation (GOx) were measured via tracer technique. The concentration of plasma glucose was higher in CLA than in non-CLA-treated cows, and the plasma ß-hydroxybutyrate concentration was higher in EFA than in non-EFA cows on d 21 PP. The eGP increased from AP to PP with elevated eGP in EFA and decreased eGP in CLA-treated cows; GOx was lower in CLA than in CTRL on d 21 PP. The plasma insulin concentration decreased after calving in all groups and was higher in CLA than in non-CLA cows at several time points. Plasma glucagon and cortisol concentrations on d 21 PP were lower in CLA than non-CLA groups. The glucagon/insulin and glucose/insulin ratios were higher in CTRL than in CLA group during the transition period. Plasma IGF-I concentration was lower in EFA than non-EFA cows on d 42 AP and was higher during the dry period and early lactation in CLA than in non-CLA cows. The IGF binding protein (IGFBP)-3/-2 ratio in blood plasma was higher in CLA than in non-CLA cows. Hepatic glycogen concentration on d 28 PP was higher, but the mRNA abundance of PC and IGFBP2 was lower in CLA than non-CLA cows on d 1 PP. The EFA treatment decreased the mRNA abundance of IGFBP3 AP and PCK1, PCK2, G6PC, PCCA, HMGCS2, IGFBP2, and INSR at several time points PP. Results indicated elevated concentrations of plasma glucose and insulin along with the stimulation of the somatotropic axis in cows treated with CLA, whereas EFA treatment stimulated eGP but not mRNA abundance related to eGP PP. The systemic effects of the combined EFA+CLA treatment were very similar to those of CLA treatment, but the effects on hepatic gene expression partially corresponded to those of EFA treatment.

Mammalian target of rapamycin signaling and ubiquitin proteasome-related gene expression in 3 different skeletal muscles of colostrum- versus formula-fed calves.

The rates of protein turnover are higher during the neonatal period than at any other time in postnatal life. The mammalian target of rapamycin (mTOR) and the ubiquitin-proteasome system are key pathways regulating cellular protein turnover. The objectives of this study were (1) to elucidate the effect of feeding colostrum versus milk-based formula on the mRNA abundance of key components of the mTOR pathway and of the ubiquitin-proteasome system in skeletal muscle of neonatal calves and (2) to compare different muscles. German Holstein calves were fed either colostrum (COL; n = 7) or milk-based formula (FOR; n = 7) up to 4 d of life. The nutrient content in formula and colostrum was similar, but formula had lower concentrations of free branched-chain AA (BCAA) and free total AA, insulin, and insulin-like growth factor (IGF)-I than colostrum. Blood samples were taken from d 1 to 4 before morning feeding and before and 2 h after the last feeding on d 4. Muscle samples from M. longissimus dorsi (MLD), M. semitendinosus (MST), and M. masseter (MM) were collected after slaughter on d 4 at 2 h after feeding. The preprandial concentrations of free total AA and BCAA, insulin, and IGF-I in plasma changed over time but did not differ between groups. Plasma free total AA and BCAA concentrations decreased in COL, whereas they increased in FOR after feeding, resulting in higher postprandial plasma total AA and BCAA concentrations in FOR than in COL. Plasma insulin concentrations increased after feeding in both groups but were higher in COL than in FOR. Plasma IGF-I concentrations decreased in COL, whereas they remained unchanged in FOR after feeding. The mRNA abundance of mTOR and ribosomal protein S6 kinase 1 (S6K1) in 3 different skeletal muscles was greater in COL than in FOR, whereas that of eukaryotic translation initiation factor 4E binding protein 1 (4EBP1) was unaffected by diet. The mRNA abundance of ubiquitin activating enzyme (UBA1) and ubiquitin conjugating enzyme 1 (UBE2G1) enzymes was not affected by diet, whereas that of ubiquitin conjugating enzyme 2 (UBE2G2) was greater (MLD) or tended to be greater (MM) in COL than in FOR. The mRNA abundance of atrogin-1 in MLD and MST was lower in COL than in FOR, whereas that of muscle ring finger protein-1 (MuRF1) was greater (MST) or tended to be greater (MLD). The abundance of MuRF1 mRNA was highest in MST, followed by MLD, and was lowest in MM. The results indicate that colostrum feeding may stimulate protein turnover that may result in a high rate of protein deposition in a muscle type-specific manner. Such effects seem to be mediated by the postprandial increase in plasma insulin.

Evaluation of electrical broad bandwidth impedance spectroscopy as a tool for body composition measurement in cows in comparison with body measurements and the deuterium oxide dilution method.

Body fatness and degree of body fat mobilization in cows vary enormously during their reproduction cycle and influence energy partitioning and metabolic adaptation. The objective of the study was to test bioelectrical impedance spectroscopy (BIS) as a method for predicting fat depot mass (FDM), in living cows. The FDM is defined as the sum of subcutaneous, omental, mesenteric, retroperitoneal, and carcass fat mass. Bioelectrical impedance spectroscopy is compared with the prediction of FDM from the deuterium oxide (DO) dilution method and from body conformation measurements. Charolais × Holstein Friesian (HF; = 18; 30 d in milk) crossbred cows and 2 HF (lactating and nonlactating) cows were assessed by body conformation measurements, BIS, and the DO dilution method. The BCS of cows was a mean of 3.68 (SE 0.64). For the DO dilution method, a bolus of 0.23 g/kg BW DO (60 atom%) was intravenously injected and deuterium (D) enrichment was analyzed in plasma and whey by stabile isotope mass spectrometry, and total body water content was calculated. Impedance measurement was performed using a 4-electrode interface and time domain-based measurement system consisting of a voltage/current converter for applying current stimulus and an amplifier for monitoring voltage across the sensor electrodes. For the BIS, we used complex impedances over three frequency decades that delivers information on intra- and extracellular water and capacity of cell membranes. Impedance data (resistance of extra- and intracellular space, cell membrane capacity, and phase angle) were extracted 1) by simple curve fit to extract the resistance at direct current and high frequency and 2) by using an electrical equivalent circuit. Cows were slaughtered 7 d after BIS and D enrichment measurements and dissected for the measurement of FDM. Multiple linear regression analyses were performed to predict FDM based on data obtained from body conformation measurements, BIS, and D enrichment, and applied methods were evaluated by cross-validation. The FDM varied widely between cows and was correlated to D enrichment in plasma ( = 0.91, < 0.05). Prediction of FDM by body size measurements was less precise ( = 0.84), but FDM prediction was more accurate using D enrichment in plasma ( = 0.90) and BIS ( = 0.99) data. Therefore, both BIS and D enrichment analysis resulted in similarly good predictions of FDM in cows, and we conclude that BIS could have the potential to predict FDM in dairy cows from 40 to 380 kg.

Effects of general anesthesia with ketamine in combination with the neuroleptic sedatives xylazine or azaperone on plasma metabolites and hormones in pigs.

Physiological research with swine often includes sedation or general anesthesia (GA), which may influence the basal physiological responses of experimental animals and may have the potential to confound or interfere with the effects of experimental factors of interest. Using 6 adult female pigs, we investigated whether selected plasma metabolites and hormones are influenced by GA induced with ketamine (K) and 2 neuroleptic sedatives, namely azaperone (A) and xylazine (X). Fasted pigs rotationally received either no drug, a single intravenous administration of A or X, or A or X combined with ketamine (AK or XK, respectively), and plasma concentrations of glucose, lactate, non-esterified fatty acids (NEFA), triglycerides (TG), glucagon, insulin, and cortisol were determined for a 5-h period following administration. Azaperone and X induced deep sedation, whereas AK and XK induced GA. Overall, the average plasma glucose concentrations were increased by A and X, with the latter exerting a stronger effect that was also associated with hypoinsulinemia ( < 0.05). Time-dependent effects indicated a more rapid increase in glucose concentration due to X or XK than AK. Plasma NEFA concentrations were elevated by A and AK and to a lesser extent by X and XK ( < 0.05). Plasma lactate and TG levels were elevated by A and AK and remained unaffected by X or XK. Plasma cortisol concentrations were elevated ( < 0.05) by X and XK and even more so with a single administration of A ( < 0.05), while the combined effect of A with ketamine resulted in the highest cortisol concentrations ( < 0.05). Our data suggest that the effects of azaperone are mediated by cortisol but less so for xylazine, which also indicates that azaperone elicits a stronger stress response in pigs. Xylazine probably induces long-lasting, fasting-state hyperglycemia through the stimulation of hepatic glucose production associated with hypoinsulinemia. A discriminant analysis based on the variation in all of the measured metabolites and hormones, collectively, indicated that ketamine induced no additional effect on the overall physiological response patterns than that of the individual sedatives. In conclusion, the neuroleptic sedatives azaperone, and to a lesser extent, xylazine, acutely affect the metabolism of pigs, so primary metabolic readouts obtained under these drugs may be confounded.

Technical note: Analytical refinements of the methane indicator archaeol in bovine feces, rumen fluid, and feedstuffs.

Archaeol (1,2-di-O-phytanyl-sn-glycerol) is a cell membrane lipid component of methanogens that has the potential to be used as a biomarker for methane production in ruminants. However, its analysis via gas chromatography-mass spectrometry (GC-MS) is challenging because of its molecular size and structure. In this study, 2 different sample preparation methods were tested, Soxhlet and sonication-aided extraction, and the methods were compared for extraction efficiency using the internal standard (IS; 1,2-di-o-hexadecyl-rac-glycerol). The extraction efficiency of the Soxhlet method for fecal archaeol was twice that of sonication. With the use of a high-temperature GC column, the retention times of IS and archaeol were 17.6 and 19.4 min, respectively, with a total run time of only 25 min. The molecule ions m/z 611.4 (IS) and m/z 725.8 (archaeol), or alternatively the fragment ion of the glycerol moiety m/z 130.0, were used for identification and quantification via GC-MS in positive chemical ionization mode. The intra-assay coefficients of variation for fecal archaeol measurements were 1.3% (m/z 725.8) and 2.1% (m/z 130.0) (n=3), respectively. Fecal archaeol quantifications did not differ between the use of the molecule or glycerol moiety ions (paired t-test, n=156). Archaeol concentrations tended to be 3.3% greater in samples stored at -20°C before drying compared with samples that were immediately dried after collection (paired t-test, n=5). The detection limit of archaeol was 0.5 µg/g of fecal dry matter (DM); no archaeol could be detected in feed samples. In different fractions of rumen fluid, archaeol levels ranged from 1.9 to 24.0 µg/g of DM. In 10 cows fed the same grass and corn silage/hay-based ration, diurnal variations of fecal archaeol levels (5 time points over 2 d) were cow dependent and ranged from 26.2 to 77.2 µg/g of DM (mean 48.4 µg/g of DM). Thus, within-animal variation in cows on the same diet was between 4 and 27%. We suggest that this finding is related to the amount and time of the latest feed intake event before the fecal sampling. Feeding pattern can determine the passage rate of digesta through the alimentary tract and thus the duration of contact time of archaea with their substrate.

Insulin-dependent glucose metabolism in dairy cows with variable fat mobilization around calving.

Dairy cows undergo significant metabolic and endocrine changes during the transition from pregnancy to lactation, and impaired insulin action influences nutrient partitioning toward the fetus and the mammary gland. Because impaired insulin action during transition is thought to be related to elevated body condition and body fat mobilization, we hypothesized that over-conditioned cows with excessive body fat mobilization around calving may have impaired insulin metabolism compared with cows with low fat mobilization. Nineteen dairy cows were grouped according to their average concentration of total liver fat (LFC) after calving in low [LLFC; LFC <24% total fat/dry matter (DM); n=9] and high (HLFC; LFC >24.4% total fat/DM; n=10) fat-mobilizing cows. Blood samples were taken from wk 7 antepartum (ap) to wk 5 postpartum (pp) to determine plasma concentrations of glucose, insulin, glucagon, and adiponectin. We applied euglycemic-hyperinsulinemic (EGHIC) and hyperglycemic clamps (HGC) in wk 5 ap and wk 3 pp to measure insulin responsiveness in peripheral tissue and pancreatic insulin secretion during the transition period. Before and during the pp EGHIC, [(13)C6] glucose was infused to determine the rate of glucose appearance (GlucRa) and glucose oxidation (GOx). Body condition, back fat thickness, and energy-corrected milk were greater, but energy balance was lower in HLFC than in LLFC. Plasma concentrations of glucose, insulin, glucagon, and adiponectin decreased at calving, and this was followed by an immediate increase of glucagon and adiponectin after calving. Insulin concentrations ap were higher in HLFC than in LLFC cows, but the EGHIC indicated no differences in peripheral insulin responsiveness among cows ap and pp. However, GlucRa and GOx:GlucRa during the pp EGHIC were greater in HLFC than in LLFC cows. During HGC, pancreatic insulin secretion was lower, but the glucose infusion rate was higher pp than ap in both groups. Plasma concentrations of nonesterified fatty acids decreased during HGC and EGHIC, but in both clamps, pp nonesterified fatty acid concentrations did not reach the ap levels. The study demonstrated a minor influence of different degrees of body fat mobilization on insulin metabolism in cows during the transition period. The distinct decrease in the glucose-dependent release of insulin pp is the most striking finding that explains the impaired insulin action after calving, but does not explain differences in body fat mobilization between HLFC and LLFC cows.

Metabolic and clinical response to Escherichia coli lipopolysaccharide in layer pullets of different genetic backgrounds supplied with graded dietary L-arginine.

L-arginine (Arg) is an essential amino acid in birds that plays a decisive role in avian protein synthesis and immune response. Effects of graded dietary Arg supply on metabolic and clinical response to Escherichia coli lipopolysaccharide (LPS) were studied over 48 hours after a single intramuscular LPS injection in 18-week-old genetically diverse purebred pullets. LPS induced a genotype-specific fever response within 4 hours post injectionem. Whereas brown genotypes showed an initial hypothermia followed by longer-lasting moderate hyperthermia, white genotypes exhibited a biphasic hyperthermia without initial hypothermia. Furthermore, within 2 hours after LPS injection, sickness behavior characterized by lethargy, anorexia, intensified respiration, and ruffled feathers appeared, persisted for 3 to 5 hours and recovered 12 hours post injectionem. The varying grades of Arg did not alter the examined traits named above, whereas insufficient Arg reduced body growth and increased relative weights of liver and pancreas significantly. At 48 hours post injectionem, increased relative weights of liver and spleen were also found in LPS treated pullets, whereas LPS decreased those of pancreas, bursa, thymus, and cecal tonsils. Moreover, LPS lowered the sum of plasma amino acids and decreased plasma concentrations of Arg, citrulline, glutamate, methionine, ornithine, phenylalanine, proline, tryptophan, and tyrosine, and increased those of aspartate, glutamine, lysine, 1- and 3-methyl-histidine. Elevating concentrations of dietary Arg led to increasing plasma concentrations of Arg, citrulline, ornithine, and 3-methyl-histidine subsequently. As quantitative expression of LPS-induced anorexia, proteolysis, and the following changes in plasma amino acids, pullets showed a significant decrease of feed and nitrogen intake and catabolic metabolism characterized by negative nitrogen balance and body weight loss in the first 24 hours post injectionem. Pullets recovered from the challenge within the second 24 hours post injectionem and changed to anabolism with re-increased feed and nitrogen intake, positive nitrogen retention, and weight gain. To conclude, present results confirmed that LPS induced numerous metabolic and physiological changes in pullet's genotypes, whereas dietary Arg affected the examined traits only slightly.

Acute effects of general anesthesia with propofol, pentobarbital or isoflurane plus propofol on plasma metabolites and hormones in adult pigs.

Experimental setups for physiological research, in which acute operative interventions need to be performed, can require inclusion of general anesthesia (GA), which may interfere or confound with the effects of the experimental factors of interest on measured variables. It was recently shown that the most commonly used sedatives/anesthetics in pigs (e.g., ketamine, xylazine, azaperone) affect physiological responses and thus the primary metabolic readouts have the potential to be confounded. To extend the search for a physiologically-friendly anesthesia regime for such studies, we investigated effects of GA induced by propofol (Prop) or pentobarbital (Pent) or propofol plus isoflurane (Prop + Isof) on plasma concentrations of commonly measured metabolites and hormones. In 2 experimental runs, 6 female pigs fitted with jugular vein catheters were used. Fasted pigs received either no drug (CON) or anesthetized rotationally either with Prop, Pent or Prop + Isof on different days, separated with washout periods of sufficient length (2 to 3 d). Six-h profiles of glucose, lactate, non-esterified fatty acids (NEFA), triglycerides (TG), cholesterol, urea as well as hormones including glucagon, insulin and cortisol were determined. Concentrations of cholesterol, urea and glucagon remained unaffected by any of the treatments ( > 0.05). Pent tended to increase cortisol from 30 to 90 min after drug administration. Glucose and lactate concentrations were increased ( < 0.05) by Prop and Pent within the first hour of GA ( < 0.05). Propofol and Pent reduced NEFA concentrations, which were more pronounced during the last 2 h of the studied period. Triglyceride concentrations were increased by all 3 agents within the first 45 min with Prop containing treatments exerting a stronger effect than Pent. Our data suggest that GA with Prop and particularly with Pent adulterate plasma metabolite and hormone profiles of pigs acutely, and thus has the potential to confound the effects of experimental factors of interest. Although Prop + Isof anesthesia did not differ from the controls, providing a physiologically-friendly GA, both single and the isoflurane-combined treatment of Prop induced hypertriglyceridemia due to the lipid adjuvant of the Prop drugs. It is concluded that readouts obtained under GA may be influenced both by physiological adulterations as response to anesthesia as well as by artifacts due to accompanying ingredients of the drug formulations.

Body composition and plasma lipid and stress hormone levels during 3 weeks of feed restriction and refeeding in low birth weight female pigs.

Compensatory growth in response to feed restriction (FR) affects deposition rates of lean and adipose tissues. It is, however, unclear whether pigs with low birth weight differ from their counterparts with normal birth weight with regard to compensatory growth. Female littermate pigs with low (UW; 1.1 kg) and normal (NW; 1.5 kg) birth weight were fed to appetite (control, CON) or feed restricted (RES) at 60% of DMI of the CON group between 78 and 98 d of age and subsequently refed at the level of the CON group until 131 d of age. Subgroups of pigs were slaughtered at 75, 98, 104, and 131 d of age to compare BW and body composition. Blood samples were taken at 98 and 119 d of age to analyze plasma metabolites and hormones. At birth UW pigs were shorter and had lower BW until 131 d of age than NW pigs ( < 0.05). Feed intake per kilogram of BW was greater in UW than in NW pigs ( < 0.01). The UW and NW pigs differed in carcass composition as indicated by greater relative subcutaneous fat at 75 d ( < 0.1), greater shoulder back fat ( < 0.05) at 98 d, and lower carcass weight at 131 d with greater abdominal and subcutaneous neck back fat in UW compared with NW pigs ( < 0.05). During FR, BW gain of RES pigs was lower than in NW pigs. The RES pigs showed greater feed intake after termination of FR until 131 d than CON pigs ( < 0.01). At 98 d RES pigs were leaner than CON pigs ( < 0.05). After 6 d of refeeding (104 d) relative fat depot weights were still smaller ( < 0.03) in RES pigs than in CON pigs. After 5 wk of refeeding, RES pigs had lower abdominal fat weights and greater plasma cortisol levels than CON pigs ( < 0.05). Regarding the plasma metabolite and hormone response, at 98-d fasting levels of plasma NEFA and glycerol were greater in RES than in CON pigs ( < 0.05), and after the drop in their levels after morning feeding ( < 0.001), plasma NEFA and glycerol and also triacylglycerol increased until the next meal in RES vs. CON pigs ( < 0.01). Plasma cortisol was greater in RES pigs after 3-wk FR ( < 0.05), whereas only a trend for increased plasma adrenalin concentrations in RES pigs at the end of the FR period and after 5 wk of refeeding was found ( < 0.1). In conclusion, UW pigs at 75 d of age (20 to 23 kg BW) had greater subcutaneous fat, whereas at 131 d (61 to 68 kg BW) they showed greater abdominal fat than NW pigs, suggesting that subcutaneous fat is deposited earlier than abdominal fat. The FR caused similar changes in body composition, plasma lipids, and stress hormones in UW and NW pigs.

The energy expenditure of 2 Holstein cow strains in an organic grazing system.

Until recently, measurements of energy expenditure (EE; herein defined as heat production) in respiration chambers did not account for the extra energy requirements of grazing dairy cows on pasture. As energy is first limiting in most pasture-based milk production systems, its efficient use is important. Therefore, the aim of the present study was to compare EE, which can be affected by differences in body weight (BW), body composition, grazing behavior, physical activity, and milk production level, in 2 Holstein cow strains. Twelve Swiss Holstein-Friesian (HCH; 616 kg of BW) and 12 New Zealand Holstein-Friesian (HNZ; 570 kg of BW) cows in the third stage of lactation were paired according to their stage of lactation and kept in a rotational, full-time grazing system without concentrate supplementation. After adaption, the daily milk yield, grass intake using the alkane double-indicator technique, nutrient digestibility, physical activity, and grazing behavior recorded by an automatic jaw movement recorder were investigated over 7d. Using the (13)C bicarbonate dilution technique in combination with an automatic blood sampling system, EE based on measured carbon dioxide production was determined in 1 cow pair per day between 0800 to 1400 h. The HCH were heavier and had a lower body condition score compared with HNZ, but the difference in BW was smaller compared with former studies. Milk production, grass intake, and nutrient digestibility did not differ between the 2 cow strains, but HCH grazed for a longer time during the 6-h measurement period and performed more grazing mastication compared with the HNZ. No difference was found between the 2 cow strains with regard to EE (291 ± 15.6 kJ) per kilogram of metabolic BW, mainly due to a high between-animal variation in EE. As efficiency and energy use are important in sustainable, pasture-based, organic milk production systems, the determining factors for EE, such as methodology, genetics, physical activity, grazing behavior, and pasture quality, should be investigated and quantified in more detail in future studies.

Influence of 4-week intraduodenal supplementation of quercetin on performance, glucose metabolism, and mRNA abundance of genes related to glucose metabolism and antioxidative status in dairy cows.

Quercetin has been shown to be a potent antioxidant, acts hepatoprotectively, and affects glucose and lipid metabolism in monogastrics. If this is also true in ruminants, quercetin could be beneficial in periparturient high-yielding dairy cows by ameliorating the negative effects of free radical formation and reducing the severity of liver lipidosis and ketosis. In a first attempt to evaluate effects of a long-term quercetin treatment, we intraduodenally administered twice daily 18 mg of quercetin (Q)/kg of body weight to 5 late-lactation (215d in milk) dairy cows over a period of 28 d. Frequent blood samples were taken before and during administration to determine plasma concentrations of flavonols and metabolites. Before and after 1 and 4 wk of Q administration, glycogen and fat content as well as mRNA expression of selected genes were measured in liver biopsies. Furthermore, euglycemic, hyperinsulinemic, and hyperglycemic clamp studies were conducted before and after 2 wk of Q administration. During the experiment, dry matter intake and most other zootechnical data remained unchanged. Milk protein content was increased in wk 2 and 4 of Q administration compared with basal values, whereas fat and lactose contents of milk remained unchanged. Plasma nonesterified fatty acids, γ-glutamyl transferase, cholesterol, glutamate dehydrogenase, triglyceride, and albumin concentrations, as well as liver fat and glycogen concentrations, were not affected by Q supplementation. Plasma glucose and ß-hydroxybutyrate concentrations in plasma decreased and increased, respectively, under the influence of quercetin. During hyperglycemic clamp conditions, the relative increase of plasma insulin was higher after 2 wk of Q administration, and a tendency for an increased rQUICKI (revised quantitative insulin sensitivity check index) was observed. The relative mRNA expression levels of selected genes related to glucose metabolism, fat metabolism, and antioxidative status were not altered after 1 or 4 wk of Q supplementation. In conclusion, the effects on insulin release and sensitivity support the assumption that administration of Q could have positive effects on the metabolic adaption of high-yielding cows to early lactation. The increase of milk protein content in response to Q supplementation needs to be verified.

First-pass uptake and oxidation of glucose by the splanchnic tissue in young goats fed soy protein-based milk diets with or without amino acid supplementation: glucose metabolism in goat kids after soy feeding.

The study was designed to examine whether feeding soy protein isolate as partial replacement of casein (CN) affects glucose metabolism in young goats and whether effects may be ameliorated by supplementation of those AA known to be lower concentrated in soy than in CN. Goat kids (d 20 of age) were fed comparable milk protein diets, in which 50% of the crude protein was either CN (control, CON), soy protein isolate (SPI), or soy protein isolate supplemented with AA (SPIA) for 43 d (n=8 per group). On d 62 of age, a single bolus dose of d-[(13)C6]glucose (10mg/kg of BW) was given with the morning diet, and simultaneously, a single bolus dose of d-[6,6-(2)H2]glucose (5mg/kg of BW) was injected into a jugular vein. Blood samples were collected between -30 and +420 min relative to the tracer administration to measure the (13)C and (2)H enrichments of plasma glucose and the (13)C enrichment of blood CO2. Glucose first-pass uptake by the splanchnic tissues was calculated from the rate of appearance of differentially labeled glucose tracer in plasma. Glucose oxidation was calculated from (13)C enrichment in blood CO2. In addition, plasma concentrations of triglycerides, nonesterified fatty acids, glucose, insulin, and glucagon were measured. On d 63 of age, kids were killed and jejunal mucosa and liver samples were collected to measure lactase mRNA levels and lactase and maltase activities in the jejunum and activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase (PEPCK) in the liver. Basal plasma glucose concentration tended to be higher in the CON than the SPIA group, whereas basal insulin was higher in the CON group than the SPI and SPIA groups, and glucagon was higher in the CON than the SPIA group. Plasma glucose and insulin concentrations increased during the first hour after feeding, whereas plasma glucagon increased immediately after feeding and after 1h of feeding. First-pass uptake and glucose oxidation were not affected by diet. Maltase activities in proximal and mid jejunum and lactase activities in mid jejunum were lower in the CON than in the SPIA group. Activities of PEPCK were higher in the SPIA than in the SPI group. In conclusion, feeding milk diets with soy protein isolate seems to affect glucose status in kids, but has no effect on first-pass uptake and oxidation of glucose. The highest activities of lactase and maltase were observed after supplementation with AA. Higher PEPCK activities in the liver may point at elevated gluconeogenic activities after AA supplementation in soy-fed kids.

Effect of feed restriction on metabolites in cerebrospinal fluid and plasma of dairy cows.

Endocrines and metabolites in the circulation act as long-term hunger or satiety signals in the brain during negative energy balance and play an important role in the control of feed intake. These signals also occur in the cerebrospinal fluid (CSF), which surrounds the hypothalamus and brainstem: 2 major centers of feed intake regulation. Thus CSF functions as a transport medium for fuel signals between blood and brain. The CSF metabolite concentrations are mainly under control of the blood-brain barriers, which provide specific carrier molecules facilitating the entry of substances required by the brain and protect the brain from factors that could impair neuronal function. The transport of small molecules such as amino acids (AA) across the blood-brain barriers may be limited by competing AA that share a common transporter for the uptake into brain. Consequently, CSF metabolite concentrations differ from those in blood. Thus it appears likely that central (CSF) rather than peripheral (blood) metabolites act as pivotal signals for the control of feed intake. However, the contribution of putative orexigenic and anorexigenic signals in CSF of cows has not been studied so far. Therefore, the aim of this study was to elucidate associations existing between both plasma and CSF metabolites, each in response to feed restriction-induced negative energy balance. Seven German Holstein dairy cows, between 87 and 96 DIM of the second lactation (milk yield, 27.9 L/d) were fed ad libitum (AL) for 4 d and CSF from the spinal cord and blood from the jugular vein was withdrawn before morning feeding at the fifth day. Subsequently, animals were feed restricted (R) to 50% of the previous AL intake for 4 d and CSF and plasma were collected at the ninth day. Body weight, feed intake, water intake, and milk production were determined. Thirty-one AA, ß-hydroxybutyric acid, cholesterol, glucose, lactate, nonesterified fatty acids, urea, and osmolality were measured in both CSF and plasma, whereas free fatty acids and volatile fatty acids were determined in plasma only. Although plasma arginine (132%), leucine (134%), lysine (117%), nonesterified fatty acids (224%), and cholesterol (112%) increased, tryptophan and carnosine decreased (-33% and -20%, respectively) in R animals as compared with AL animals. In CSF, concentrations of these metabolites were not affected after R feeding, suggesting that these identified plasma metabolites have only little potential to contribute to central feed intake regulatory signaling in cows. By contrast, in CSF, serine, threonine, and tyrosine decreased (-20, -24, and -31%, respectively) after R feeding. Therefore, these 3 AA are potential centrally acting anorexigenic signals in cows.

Maturation of endogenous glucose production in preterm and term calves.

Glucose disposability is often impaired in neonatal calves and even more in preterm calves. The objective of this study was to investigate ontogenic maturation of endogenous glucose production (eGP) in calves and its effects on postnatal glucose homeostasis. Calves (n = 7 per group) were born preterm (PT; delivered by section 9 d before term) or at term (T; spontaneous vaginal delivery), or spontaneously born and fed colostrum for 4 d (TC). Blood samples were taken immediately after birth and before and 2h after feeding at 24h after birth (PT; T) or on d 4 of life (TC) to determine metabolic and endocrine changes. After birth (PT and T) or on d 3 of life (TC), fasted calves were gavaged with deuterium-labeled water to determine gluconeogenesis (GNG) and intravenously infused with [U(13)C]-glucose to measure eGP and glucose oxidation (GOx) in blood plasma. After slaughter at 26h after birth (PT, T) or on d 4 of life (TC), glycogen concentrations in liver and hepatic mRNA concentrations and enzyme activities of pyruvate carboxylase, phosphoenolpyruvate carboxykinase (PEPCK), and glucose-6-phosphatase were measured. Preterm calves had the lowest plasma concentrations of cortisol and 3,5,3'-triiodothyronine at birth. Plasma glucose concentrations from d 1 to 2 decreased more, but plasma concentrations of lactate and urea and glucagon:insulin ratio were higher in PT than in T and TC calves. The eGP, GNG, GOx, as well as hepatic glycogen concentrations and PEPCK activities, were lowest in PT calves. Results indicate impaired glucose homeostasis due to decreased eGP in PT calves and maturation of eGP with ontogenic development.

Energy expenditure of grazing cows and cows fed grass indoors as determined by the 13C bicarbonate dilution technique using an automatic blood sampling system.

The objectives of the study were to assess the 13C bicarbonate dilution technique using an automatic blood sampling system and to use this technique to estimate energy expenditure (EE) based on the CO2 production of 14 lactating Holstein cows on pasture or in a freestall barn. The effects of physical activity and eating behavior on EE were also assessed. Cows were exposed to each feeding system in a crossover design with two 14-d experimental periods, each consisting of an adaptation period and a 7-d data collection period. Cows either grazed on pasture or had ad libitum access, in the freestall barn, to grass cut daily from the same paddock. All cows were supplemented with a cereal-based concentrate. The EE of each cow was determined from 0700 to 1300 h on 1 d of each collection period. Blood samples for the 13C bicarbonate dilution technique were taken either manually in the barn or using an automatic blood sampling system on pasture. Eating pattern and physical activity were recorded from 0700 to 1300 h using a behavior recorder and an activity meter, respectively. Milk yield was recorded daily. Individual feed intake was estimated using the alkane double-indicator technique. Two preceding experiments confirmed that the sampling technique (manual or automatic) and the following storage of the blood samples (frozen directly after withdrawal or first cooled on ice and then frozen 6 h later) had no effect on 13CO2 enrichment in the extracted blood CO2 or on the subsequent calculation of CO2 production. During the 6-h measurement period, the EE of cows on pasture was higher than that of cows in the freestall barn. Daily feed intake and milk production were not affected by the feeding treatment. Grazing cows spent more time walking and less time standing and lying than did cows fed indoors. Time spent eating was greater and time spent ruminating was lower for cows on pasture compared with grass-fed cows in the barn. In conclusion, the 13C bicarbonate dilution technique, combined with an automatic blood sampling system, is a suitable method to determine the EE of lactating dairy cows on pasture. Positive correlations between EE and walking and eating time indicate that the higher energy requirements of dairy cows on pasture may be at least partly caused by a higher level of physical activity. However, before specific recommendations about additional energy supply can be given, it must be determined whether EE measured over 6 h can be extrapolated to 24 h. Furthermore, the apparent inconsistency between EE, feed intake, and milk production needs to be resolved.

Limited and excess dietary protein during gestation affects growth and compositional traits in gilts and impairs offspring fetal growth.

The aim of this study was to investigate whether dietary protein intake during gestation less than or greater than recommendations affects gilts growth and body composition, gestation outcome, and colostrum composition. German Landrace gilts were fed gestation diets (13.7 MJ of ME/kg) containing a low (n = 18; LP, 6.5% CP), an adequate (n = 20; AP, 12.1%), or a high (n = 16; HP, 30%) protein content corresponding to a protein:carbohydrate ratio of 1:10.4, 1:5, and 1:1.3, respectively, from mating until farrowing. Gilts were inseminated by semen of pure German Landrace boars and induced to farrow at 114 d postcoitum (dpc; Exp. 1). Energy and protein intake during gestation were 33.3, 34.4, and 35.8 MJ of ME/d (P < 0.001) and 160, 328, and 768 g/d, respectively, in LP, AP, and HP gilts (P < 0.001). From insemination to 109 dpc, BW gain was least in LP (42.1 kg), intermediate in HP (63.1 kg), and greatest in AP gilts (68.3 kg), whereas increase of backfat thickness was least in gilts fed the HP diet compared with LP and AP diets (3.8, 5.1, 5.0 mm; P = 0.01). Litter size, % stillborn piglets, and mummies were unaffected (P > 0.28) by the gestation diet. Total litter weight tended to be less in the offspring of LP and HP gilts (14.67, 13.77 vs. 15.96 kg; P = 0.07), and the percentage of male piglets was greater in litters of HP gilts (59.4%; P < 0.01). In piglets originating from LP and HP gilts, individual birth weight was less (1.20, 1.21 vs. 1.40 kg; P = 0.001) and birth weight/crown-rump length ratio was reduced (45.3, 46.4 vs. 50.7 g/cm; P = 0.003). Colostrum fat (7.8, 7.4 vs. 8.1%) and lactose concentrations (2.2, 2.1 vs. 2.6%) tended to be reduced in LP and HP gilts (P = 0.10). In Exp. 2, 28 gilts (LP, 10; AP, 9; HP, 9) were treated as in Exp. 1 but slaughtered at 64 dpc. At 64 dpc, LP gilts were 7% lighter than AP gilts (P = 0.03), whereas HP gilts were similar to AP gilts. Body composition was markedly altered in response to LP and HP feeding with less lean (P < 0.01) and greater fat content (P = 0.02 to 0.04) in LP and less fat content (P = 0.02 to 0.04) in HP gilts. Fetal litter weight and number, and embryonic survival at 64 dpc were not affected by the diets. These results indicated that gestation diets containing protein at 50 and 250% of recommendations and differing in protein:carbohydrate ratio led to marked changes in protein and fat metabolism in gilts resulting in fetal growth retardation of 15%, which mainly occurred during the second half of gestation.