Studies of glucose metabolism in Hymenolepis diminuta using 13C nuclear magnetic resonance

The metabolism in vitro of U-¹³C-glucose and NaH¹³CO₃ by two strains of adult Hymenolepis diminuta, the ANU and UT strains, was examined using ¹³C n.m.r. spectroscopy. The incubation medium and perchlorate extracts from worms incubated in vitro with U-¹³C-glucose showed incorporation of significant quantities of label into the end products succinate, lactate and acetate, and also into glycogen. Similar experiments with NaH¹³CO₃ showed incorporation principally into succinate C-1,4, plus significant labelling also in lactate C-1. This shows that nutochondrial malate or pyruvate contributes to the cytosolic pyruvate pool in H. diminuta. The metabolism of U-¹³C-glucose was followed directly by incubating live worms directly in the spectrometer. Worms from 24 h-fasted hosts metabolised the added glucose completely during an experimental period of 2 h and incorporation of label was evident in the time course spectra. Parasites from fed hosts metabolised the added glucose more slowly. This work confirms the accepted routes of glucose metabolism in H. diminuta and demonstrates the utility of the n.m.r. technique in investigating the metabolism of parasites.     

Identifying the limitations for growth in low performing piglets from birth until 10 weeks of age

The evolution of hyper-prolific pig breeds has led to a higher within-litter variation in birth weight and in BW gain during the nursery phase. Based on an algorithm developed in previous research, two populations from a pool of 368 clinically healthy piglets at 6 weeks of age were selected: a low (LP) and a high (HP) performing population and their development was monitored until the end of the nursery phase (10 weeks of age). To understand the cause of the variation in growth between these populations we characterized the LP and HP piglets in terms of body morphology, behaviour, voluntary feed intake, BW gain, and apparent total tract and ileal nutrient digestibility. Piglets were housed individually and were fed a highly digestible diet. At selection, 6 weeks of age, the BW of LP and HP piglets were 6.8±0.1 and 12.2±0.1 kg, respectively. Compared with the LP piglets the HP piglets grew faster (203 g/day), ate more (275 g/day) from 6 to 10 weeks of age and were heavier at 10 weeks (30.0 v. 18.8 kg, all P<0.01). Yet, the differences in average daily gain and average daily feed intake disappeared when compared per kg BW^0.75. Assuming similar maintenance requirements per kg BW^0.75 the efficiency of feed utilization above maintenance was 0.1 g/g lower for the LP piglets (P=0.09).The gain : feed ratio was similar for both groups. LP piglets tended to take more time to touch a novel object (P=0.10), and spent more time eating (P<0.05). At 10 weeks, LP piglets had a higher body length and head circumference relative to BW (P<0.01). Relative to BW, LP had a 21% higher small intestine weight; 36% longer length, and relative to average FI, the small intestinal weight was 4 g/kg higher (both P=<0.01). Apparent total tract and ileal dry matter, N and gross energy digestibility were similar between groups (P>0.10). We concluded that the low performance of the LP piglets was due to their inability to engage compensatory gain or compensatory feed intake as efficiency of nutrient utilization and feed intake per kg BW^0.75 was unaffected. LP piglets tend to be more fearful towards novel objects. The morphological comparisons, increased body length and head circumference relative to BW imply that LP piglets have an increased priority for skeletal growth.     

Substrates for anaerobic CO2-production by the goldfish,Carassius auratus (L.): Decarboxylation of14C-labeled metabolites

Summary Goldfish acclimated to normal oxygen levels and to 20°C were made anoxic and injected i.p. with U-¹⁴C-glucose, 6-¹⁴C-glucose, U-¹⁴C-lactate, 3-¹⁴C-lactate, 1-¹⁴C-acetate or 3,4-¹⁴C-glutamate. Radioactivity released into the water (total¹⁴C and¹⁴CO₂) was monitored over a period of about 12 h. With the exception of 3,4-¹⁴C-glutamate from which only 4% was released, the release of¹⁴C from the other compounds was found to be over 30%. The fraction of the radioactivity released as CO₂ varied with the compound injected but was high during the first 4 h after injection. It is argued that the acid-stable¹⁴C component is ethanol, which arises by the combined action of a modified pyruvate dehydrogenase and of alcohol dehydrogenase in muscle (Shoubridge and Hochachka 1980; Mourik et al. 1982).¹⁴CO₂ release from 3-¹⁴C-lactate, 6-¹⁴C-glucose, 3,4-¹⁴C-glutamate and 1-¹⁴C-acetate cannot be explained by ethanol fermentation. Neither was there a stoichiometric relation between¹⁴CO₂ and¹⁴C-ethanol release after U-¹⁴C-glucose and U-¹⁴C-lactate injection. It is concluded that at least 20% of the CO₂ released is produced by Krebs cycle activity.     

Vitamin A deficiency in mice alters host and gut microbial metabolism leading to altered energy homeostasis

Vitamin A deficiency (A−) is a worldwide public health problem. To better understand how vitamin A status influences gut microbiota and host metabolism, we systematically analyzed urine, cecum, serum and liver samples from vitamin A sufficient (A+) and deficient (A−) mice using ¹H NMR-based metabolomics, quantitative (q)PCR and 16S rRNA gene sequencing coupled with multivariate data analysis. The microbiota in the cecum of A− mice showed compositional as well as functional shifts compared to the microbiota from A+ mice. Targeted ¹H NMR analyses revealed significant changes in microbial metabolite concentrations including higher butyrate and hippurate and decreased acetate and 4-hydroxyphenylacetate in A+ relative to A− mice. Bacterial butyrate-producing genes including butyryl-CoA:acetate CoA-transferase and butyrate kinase were significantly higher in bacteria from A+ versus bacteria from A− mice. A− mice had disturbances in multiple metabolic pathways including alterations in energy (hyperglycemia, glycogenesis, TCA cycle and lipoprotein biosynthesis), amino acid and nucleic acid metabolism. A− mice had hyperglycemia, liver dysfunction, changes in bacterial metabolism and altered gut microbial communities. Moreover, integrative analyses indicated a strong correlation between gut microbiota and host energy metabolism pathways in the liver. Vitamin A regulates host and bacterial metabolism, and the result includes alterations in energy homeostasis.     

Associations of acute stress and overnight heart rate with feed efficiency in beef heifers

Proxies have the potential to accelerate feed efficiency (residual feed intake (RFI); kg dry matter/day) improvement, assisting with the reduction of beef cattle feed costs and environmental impact. Heart rate (HR) (beats per minute (BPM)) is associated with feed efficiency and influenced by autonomic activity and peripheral metabolism, suggesting HR could be used as a proxy for feed efficiency. Objectives were to assess associations between overnight HR, lying patterns and RFI, and between acute stress HR and RFI. Heifer calves (n=107; 408±28 days of age, 341±42.2 kg) and yearling heifers (n=36; 604±92 days of age, 539±52.2 kg) were exposed to a performance test to determine productive performance. Overnight HR (electrode based) and lying patterns (accelerometer based) were monitored on a subgroup of heifer calves (n=40; 20 lowest RFI; 20 highest RFI). In the 10-min acute stress assessment, all heifers were individually exposed to the opening and closing of an umbrella and HR before (HR_BEF), in response to (HR_MAX), after (HR_AFT) and change (HR_CHG; HR_AFT−HR_BEF) as a result of exposure were determined. Using polynomial regression, rate of HR decrease pre-exposure (β₁) and rates of HR increase (β₂) and decrease (β₃, β₄) post-exposure were determined. Heifer calves in the overnight assessment were classified into equal RFI groups (low RFI; high RFI) and HR means were treated as repeated measures and compared using multiple regression. In the acute stress assessment, heifers were classified within cattle category into equal RFI groups (low RFI; high RFI) and means and polynomial regression parameters were compared using multiple regression. Low-RFI heifer calves had a lower overnight HR (69.2 v. 72.6 BPM), similar HR change from lying to standing intervals (8.9 v. 9.2 BPM) and similar time lying (61.1% v. 64.5%) compared with high-RFI heifer calves. Low-RFI heifer calves had a higher absolute HR_MAX (162.9 v. 145.7 BPM) and β₂ (−0.34 v. −0.20) than high-RFI heifer calves. Low-RFI yearling heifers had similar acute stress HR means and a lower β₁ (0.003 v. 0.006) than high-RFI yearling heifers. Overnight HR and acute stress HR are potential indicators of RFI in heifer calves. However, acute stress HR results varied in yearling heifers, suggesting previous handling experience and/or age influence stress response. Pending further development (predictive ability, repeatability), the acute stress assessment could have potential for on-farm application as a feed efficiency proxy in young heifers with minimal handling experience.     

Relation between feeding behaviour and energy metabolism in pigs fed diets enriched in dietary fibre and wheat aleurone

Feed intake and its daily pattern are regulated both at a short and a long term by several control pathways, including energy balance regulation. This trial aimed to determine the effect of dietary fibre (DB) (mix of wheat, soy and sugar beet pulp fibres) and aleurone supplementation and their interaction on energy and nitrogen balances in growing pigs with ad libitum access to feed. Forty pigs (BW: 35 kg) were fed diets differing by fibre concentration (NDF concentration: 10% or 14% DM) and aleurone supplementation (0, 2 or 4 g/kg) during 3 weeks. Pigs were housed individually in a respiration chamber during the last week to record feeding behaviour and measure energy and nitrogen balances (n = 36). Glucose oxidation was studied on the 6th day with an injection of [U-¹³C] glucose and measurement of ¹³CO₂ production. There was no significant interaction between DB inclusion and aleurone supplementation on any variables characterizing feeding behaviour. Pigs had less but longer meals with high level of DB, with an increased interval between two meals without effect on daily feed intake. The meal frequency significantly decreased when aleurone supplementation increased. Total tract apparent digestibility coefficient of DM, organic matter, ash, nitrogen and gross energy decreased when pigs received high DB level. Dietary fibre level increased significantly faecal excreted nitrogen. Aleurone supplementation decreased nitrogen retention. Free access to the feed induced a great individual variability not only in feed intake level (from 784 to 2290 g/day) but also in feeding behaviour (from 5.5 to 21.5 meals per day). This variability can be linked with the importance of underlying feed intake regulation pathways and difference in energy balance and metabolism efficiency. Several profiles of metabolism efficiency can be discriminate, thanks to a clustering based on feeding behaviour and pre-prandial concentrations of metabolites and hormones. In conclusion, DB inclusion decreased meal frequency, increased average meal size, decreased total tract apparent faecal digestibility coefficient of nitrogen and gross energy. Supplementation of aleurone decreased average daily feed intake with a reduction of the meal number per day, without modification of average meal size. Aleurone supplementation decreased nitrogen retention and nutrient deposition. Independently of experimental diets, the high individual variability permitted discriminating different profiles with different metabolic strategies. Efficient pigs with a high energy retention as protein and lipid seem to be able to adapt their metabolism according to energy sources.     

Review: divergent selection for residual feed intake in the growing pig

This review summarizes the results from the INRA (Institut National de la Recherche Agronomique) divergent selection experiment on residual feed intake (RFI) in growing Large White pigs during nine generations of selection. It discusses the remaining challenges and perspectives for the improvement of feed efficiency in growing pigs. The impacts on growing pigs raised under standard conditions and in alternative situations such as heat stress, inflammatory challenges or lactation have been studied. After nine generations of selection, the divergent selection for RFI led to highly significant (P<0.001) line differences for RFI (−165 g/day in the low RFI (LRFI) line compared with high RFI line) and daily feed intake (−270 g/day). Low responses were observed on growth rate (−12.8 g/day, P<0.05) and body composition (+0.9 mm backfat thickness, P=0.57; −2.64% lean meat content, P<0.001) with a marked response on feed conversion ratio (−0.32 kg feed/kg gain, P<0.001). Reduced ultimate pH and increased lightness of the meat (P<0.001) were observed in LRFI pigs with minor impact on the sensory quality of the meat. These changes in meat quality were associated with changes of the muscular energy metabolism. Reduced maintenance energy requirements (−10% after five generations of selection) and activity (−21% of time standing after six generations of selection) of LRFI pigs greatly contributed to the gain in energy efficiency. However, the impact of selection for RFI on the protein metabolism of the pig remains unclear. Digestibility of energy and nutrients was not affected by selection, neither for pigs fed conventional diets nor for pigs fed high-fibre diets. A significant improvement of digestive efficiency could likely be achieved by selecting pigs on fibre diets. No convincing genetic or blood biomarker has been identified for explaining the differences in RFI, suggesting that pigs have various ways to achieve an efficient use of feed. No deleterious impact of the selection on the sow reproduction performance was observed. The resource allocation theory states that low RFI may reduce the ability to cope with stressors, via the reduction of a buffer compartment dedicated to responses to stress. None of the experiments focussed on the response of pigs to stress or challenges could confirm this theory. Understanding the relationships between RFI and responses to stress and energy demanding processes, as such immunity and lactation, remains a major challenge for a better understanding of the underlying biological mechanisms of the trait and to reconcile the experimental results with the resource allocation theory.     

Highly thermostable carbonic anhydrase from Persephonella marina EX-H1: Its expression and characterization for CO2-sequestration applications

The codon-optimized carbonic anhydrase gene of Persephonella marina EX-H1 (PMCA) was expressed and characterized. The gene with the signal peptide removed, PMCA(sp−), resulted in the production of approximately five times more purified protein than from the intact gene PMCA using an Escherichia coli expression system. PMCA(sp−) is formed as homo-dimer complex. PMCA(sp−) has a wide pH tolerance (optimum pH 7.5) and a high thermostability even at 100 °C (88 min of thermal deactivation half-life). The melting temperature for PMCA(sp−) was 84.5 °C. The apparent k_cat and K_m values for CO₂ hydration were 3.2 × 10⁵ s⁻¹ and 10.8 mM. The activity of the PMCA(sp−) enzyme was enhanced by Zn²⁺, Co²⁺, and Mg²⁺, but was strongly inhibited by Cu²⁺, Fe³⁺, Al³⁺, Pb²⁺, Ag⁺, and Hg²⁺. PMCA(sp−) readily catalyzed the hydration of CO₂, precipitating CaCO₃ as calcite in the presence of Ca²⁺.     

Effects of oral supplementation with Spirulina and Chlorella on growth and digestive health in piglets around weaning

Weaning of piglets is associated with important changes in gut structure and function resulting from stressful events such as separation from the sow, moving to a new facility and dietary transition from a liquid to a solid feed. This may result in post-weaning diarrhoea and a decrease in feed intake and growth. In humans, the cyanobacterium Spirulina platensis (SP) and the freshwater microalga Chlorella vulgaris (CV) are known for their beneficial health effects. This study aimed to determine the effects of early oral administration of Spirulina and Chlorella in piglets on mucosal architecture and cytokine expression in the intestine around weaning, and consequences on growth performance and diarrhoea incidence. The experiment was conducted on 108 suckling piglets of 14 days of age (initial BW=4.9±0.7 kg) and weaned at 28 days of age (day 0). Animals received orally 385 mg/kg BW per day of SP or CV, or water (negative control (NC)) during 4 weeks from day −14 to day 14 and their growth performance was measured daily. After weaning, growth, feed intake and diarrhoea incidence were measured daily. Intestinal morphology and functionality were assessed at day −1, day 2, and day 14. During the suckling period, average daily gain (ADG) in SP piglets was higher, resulting in a higher weaning BW compared to NC and CV piglets (P<0.05). No significant difference between treatments was observed for ADG, average daily feed intake, and gain to feed (G : F) ratio after weaning, but the extent of growth retardation after weaning was the lowest in piglets supplemented with Chlorella (P<0.01). Supplementation with Spirulina reduced diarrhoea incidence by 50% from day 0 to day 14 (P<0.05). Mucosal architecture at the jejunum was unaffected by Spirulina or Chlorella administration (P>0.10). Shorter ileal villi were measured in SP and CV piglets than in NC piglets (P<0.05). Cytokine expression did not differ between treatments in response to weaning. At day 14, IL-8 expression in the ileum was higher in SP piglets, while IL-1β expression in the jejunum was higher in CV piglets (P<0.05). This study shows that Spirulina administration around weaning alleviates diarrhoea in weaned piglets, without marked modulation of local inflammation.     

Pigs that are divergent in feed efficiency,differ in intestinal enzyme and nutrient transporter gene expression,nutrient digestibility and microbial activity

Feed efficiency is an important trait in the future sustainability of pig production, however, the mechanisms involved are not fully elucidated. The objective of this study was to examine nutrient digestibility, organ weights, select bacterial populations, volatile fatty acids (VFA’s), enzyme and intestinal nutrient transporter gene expression in a pig population divergent in feed efficiency. Male pigs (n=75; initial BW 22.4 kg SEM 2.03 kg) were fed a standard finishing diet for 43 days before slaughter to evaluate feed intake and growth for the purpose of calculating residual feed intake (RFI). Phenotypic RFI was calculated as the residuals from a regression model regressing average daily feed intake (ADFI) on average daily gain (ADG) and midtest BW^0.60 (MBW). On day 115, 16 pigs (85 kg SEM 2.8 kg), designated as high RFI (HRFI) and low RFI (LRFI) were slaughtered and digesta was collected to calculate the coefficient of apparent ileal digestibility (CAID), total tract nutrient digestibility (CATTD), microbial populations and VFA’s. Intestinal tissue was collected to examine intestinal nutrient transporter and enzyme gene expression. The LRFI pigs had lower ADFI (P<0.001), improved feed conversion ratio (P<0.001) and an improved RFI value relative to HRFI pigs (0.19 v. −0.14 SEM 0.08; P<0.001). The LRFI pigs had an increased CAID of gross energy (GE), and an improved CATTD of GE, nitrogen and dry matter compared to HRFI pigs (P<0.05). The LRFI pigs had higher relative gene expression levels of fatty acid binding transporter 2 (FABP2) (P<0.01), the sodium/glucose co-transporter 1 (SGLT1) (P<0.05), the glucose transporter GLUT2 (P<0.10), and the enzyme sucrase–isomaltase (SI) (P<0.05) in the jejunum. The LRFI pigs had increased populations of lactobacillus spp. in the caecum compared with HRFI pigs. In colonic digesta HRFI pigs had increased acetic acid concentrations (P<0.05). Differences in nutrient digestibility, intestinal microbial populations and gene expression levels of intestinal nutrient transporters could contribute to the biological processes responsible for feed efficiency in pigs.     

Metabolic precursors of surfactant disaturated-phosphatidylcholine in preterms with respiratory distress

Our objective was to study the metabolic precursors of surfactant disaturated-phosphatidylcholine (DSPC) in preterm infants with respiratory distress syndrome (RDS) on mechanical ventilation. We performed 46 DSPC kinetic studies in 23 preterms on fat-free parenteral nutrition and mechanical ventilation (birth weight = 1167 ± 451 g, gestational age = 28.5 ± 2.0 weeks). Eight infants received a simultaneous intravenous infusion of U¹³C-glucose and [16,16,16]²H-palmitate, eight infants received U¹³C-glucose and ²H₂O, and seven received U¹³C-palmitate and ²H₂O. Surfactant DSPC kinetics were calculated from the isotopic enrichments of DSPC-palmitate from sequential tracheal aspirates and its metabolic precursors in plasma or urine. DSPC fractional synthesis rate (FSR) was 17 ± 11, 21 ± 16, and 15 ± 6%/day from glucose, palmitate, and body water, respectively (P = 0.36). DSPC-FSR from U¹³C-glucose and ²H₂O were significantly correlated and yielded similar estimates (difference of –0.1 ± 3%) (P = 0.91). The difference in the 15 infants receiving palmitate versus ²H₂O or palmitate versus glucose was +6.0 ± 12%/day (P = 0.21). There was a significant correlation between DSPC-FSRs from plasma glucose and plasma FFA. The contribution of glucose versus palmitate to DSPC-FSR was 49 ± 20% versus 51 ± 20%, respectively. Plasma glucose and FFA showed similar contributions to DSPC-FSR in infants with RDS and fat-free parenteral nutrition. FSRs from ²H₂O or glucose were highly correlated.     

Potassium conductances and proliferation in conditionally immortalized renal glomerular mesangial cells from the H-2Kb-tsA58 transgenic mouse

The effects of the temperature-sensitive, immortalizing Simian Virus 40 T antigen, tsA58, on whole-cell potassium conductances were assessed in renal glomerular mesangial cells from H-2K^b-tsA58 transgenic mice [1]. MTT cell viability assay data indicated that in permissive (33°C, 50 U ml⁻¹ γ-interferon, IFN+) and non-permissive (37°C, without γ-interferon, IFN−) culture conditions the oncogene was active and inactive respectively. In IFN+ cells whole-cell currents were inhibited by 10 mM 4-aminopyridine, 1 mM ATP and glibenclamide (glyburide, IC₅₀=0.4 μM) and stimulated by cromakalim (EC₅₀=40 μM). Furthermore, increases in pipette free calcium activity stimulated the potassium conductance (EC₅₀=0.5 μM). Apamin inhibited this conductance (IC₅₀=9 nM). None of these effects were observed in IFN− cells. The potassium conductance in IFN− cells was activated by a hyposmotic shock and this was inhibited by Gd³⁺. These data indicate that (1) conductances consistent with ATP-sensitive and small, calcium-activated potassium channels are found in IFN+ cells, (2) an osmotically-sensitive channel is found in IFN− cells and (3) channel expression is dependent upon the activation of tsA58.     

Effects of various energy and protein levels during sequential feeding on feed preferences in meat-type chickens

Short-term feed preferences were studied in individually caged chickens fed sequentially in order to understand a previously described imbalance in the intake of diets offered. Sequential feeding (SF) was carried out for four 48 h cycles in male broiler chickens. The diets varied in energy (2800 (E−) and 3200 kcal/kg (E+)) and protein (230 (P+) and 150 g/kg (P−)) contents. SF was compared to standard feeding (C) (3000 kcal/kg ME and CP = 190 g/kg). In experiment 1, three treatments were used: C, S_E (E− followed by E+) and S_E′ (E+ followed by E−). Four treatments were used in experiment 2: C, S_P (P+ followed by P−), S_E and S_EP (P+E− followed by P−E+). Total feed intake was measured during the SF period. After this, short-term preferences were evaluated with a choice test on chickens previously fed with the same feeds during the SF period (experienced birds) and in C chickens (naïve birds). In both experiments, total feed intake was similar among treatments and the percentage of each feed consumed was not significantly different from controls (50%). In experiment 1, S_E and S_E′ chickens over-consumed E+ and under-consumed E− diets only during the first 15 min of the fourth cycle. The choice test indicated that experienced chickens preferred E+, while naïve chickens preferred E−. Similarly, in experiment 2, chickens over-consumed E+ and E+P− during the first 15 min of the fourth cycle, but the intake of diets varying in protein content was not different from controls. During the choice test, as in experiment 1, experienced chickens preferred E+, while naïve chickens preferred E−. There was a slight preference for the protein-poor diet in naïve birds and there was no preference in the diet varying in both protein and energy contents. Experience modified choice between feeds varying in energy content but not in protein. When feeds were known, preference for energy affected the feed intake immediately after switching from one diet to the other, although lower with the diet also varying in protein, it did not influence the total intake of each diet. Interactions between the nutritional properties and sensorial cues of feed could explain these results.     

Effects of galactose on direct and indirect pathway estimates of hepatic glycogen synthesis

Hepatic glycogen is formed by direct and indirect pathways whose activities reflect altered nutrition or disease. Direct/indirect pathway measurements often involve test meals where ～10% of carbohydrate is galactose, but its effects on direct/indirect pathway estimates are unknown. Therefore, direct/indirect pathway contributions in 24-h fasted rats given 2 g/kg 100% glucose (GLU, n=6) or 90% glucose–10% galactose (GLU+GAL, n=6) were measured by [U-¹³C]glucose dilution and by position-5/position-2 glycogen enrichment (H5/H2) from 2H₂O. For GLU+GAL, galactose glycogenesis was independently measured with [1-¹³C]galactose. Glycogenesis was equivalent in both groups but for GLU+GAL, 23±4% of glycogen was derived from galactose. [U-¹³C]glucose reported a 30±3% direct pathway contribution to glycogenesis for GLU but only 20±3% for GLU+GAL (p=0.012 vs. GLU). H5/H2 yielded identical direct pathway estimates (32±3% GLU, 29±6% GLU+GAL). Thus, galactose glycogenesis was undetected by H5/H2 while [U-¹³C]glucose reported a reduced direct/indirect pathway ratio. With [1-¹³C]galactose also present, correct glycogenic source contributions were obtained.     

Associations between feed efficiency,sexual maturity and fertility-related measures in young beef bulls

The beef industry has emphasized the improvement of feed utilization, as measured by modeling feed intake through performance traits to calculate residual feed intake (RFI). Evidence supports an inverse relationship between feed efficiency and reproductive function. The objective of this study was to determine the relationship of reproductive assessments and RFI unadjusted (RFI_Koch) or adjusted for body composition (RFI_us) and the relationship among fertility-related parameters. In total, 34 crossbred bulls were housed together for 112 days of performance evaluation, followed by assessment of scrotum IR imaging, scrotal circumference, testes ultrasonography and semen quality parameters at 377±33.4 days of age. Bulls were slaughtered at 389±34.0 days of age, and analyses of carcass composition, biometrics and histomorphometry of the testis and epididymis were conducted. Bulls were grouped into two subpopulations based on divergence of RFI, and within each RFI model either by including 50% of the population (Halves, high and low RFI, n=17) or 20.6% extremes of the population (Tails, high and low RFI, n=7). The means of productive performance and fertility-related measures were compared through these categories. Pearson’s correlation was calculated among fertility-related measures. In the Halves subpopulation of the RFI_us, sperm of low-RFI bulls had decreased progressive motility (47.30% v. 59.90%) and higher abundance of tail abnormalities (4.30% v. 1.80%) than that of high-RFI bulls. In the Tails subpopulation of the RFI_Koch, low RFI displayed less variation in the scrotum surface temperature (0.62°C v. 1.16°C), decreased testis echogenicity (175.50 v 198.00 pixels) and larger (60.90 v. 56.80 mm²) but less-developed seminiferous tubules than high-RFI bulls. The evaluation of fertility-related parameters indicated that a higher percentage of immature seminiferous tubules was correlated with occurrence of sperm with distal droplets (r=0.59), a larger temperature variation at the top of the scrotum was correlated with improved sperm progressive motility (r=0.38), a lower occurrence of sperm loose head abnormalities was correlated with larger temperature variation at the lower part of the scrotum (r=−0.43), and a lower minimum testis echogenicity (r=−0.59) and smaller scrotal circumference (r=0.72) were correlated with age. The adjustment for body composition (RFI determination) enabled distinct biological inferences about reproduction and feed efficiency when compared with the non-adjusted model. However, both RFI models and the correlation analysis supported the hypothesis that feed-efficient bulls have features of delayed sexual maturity. Overall, the assessment of fertility-related measurements is important to avoid the improvement of feed efficiency at the expense of reproductive function in young bulls.     

Thermoregulation at birth differs between piglets from two genetic lines divergent for residual feed intake

Thermoregulation is essential to piglets' neonatal survival. This study used infrared thermography (IRT) to assess thermoregulation abilities of piglets from two lines divergent for residual feed intake (RFI). At birth, morphology (weight, length, width and circumference), vigour (respiration, mobility and vocalisation), and rectal temperature were recorded from piglets of the 11th generation of the low RFI (LRFI, more efficient; n = 34) and the high RFI (HRFI, less efficient; n = 28) lines. Infrared thermography images were taken at 8, 15, 30 and 60 min post partum. Temperatures of the ear base and tip, and of the back (i.e. shoulders to rumps) were extracted (Thermacam Researcher Pro 2.0) and analysed with linear mixed models (SAS 9.4). Piglets had different average hourly weight gain (HRFI = 7.1 ± 1.3 g/h, LRFI = 3.6 ± 1.3 g/h; P < 0,001) but did not differ in morphology or vigour. All temperatures increased overtime. At birth, piglets' rectal temperature was correlated with the initial temperature of the ear base and the maximum back temperature (0.37 and 0.33, respectively; P < 0.05). High residual feed intake piglets had lower ear tip temperatures than LRFI piglets at 15 (24.7 ± 0.37 °C vs. 26.3 ± 0.36 °C, respectively; F_{1, 63.5} = 9.11, P < 0.005) and 30 min post partum (26.2 ± 0.47 °C vs. 27.6 ± 0.44 °C, respectively; F_{1, 66.9} = 4.52, P < 0.05). Moreover, thermal pattern of the ear tip differed between the two genetic lines. In conclusion, IRT allowed non-invasive assessment of piglets' thermoregulation abilities and indicated an influence of genetic selection for RFI on neonatal thermoregulation abilities.     

Effect of litter size,milk replacer and housing on production results of hyper-prolific sows

The modern hyper-prolific sow gives birth to more piglets than she has functional teats (in the following called supernumerary piglets). The aim of the present study was (1) to investigate the production consequences of hyper-prolific sows rearing supernumerary piglets equal to the mean live-born litter size, and (2) investigate whether potential negative effects on survival and growth could be alleviated by providing access to milk replacer and/or providing easier access to the udder (by loose housing). At day 1 (D1) postpartum (pp), 93 litters were standardised to 14 or 17 piglets (LS14/LS17) after which no piglets were moved between sows leading to decreased litter size if piglets died. Litters were provided with or without milk replacer in milk cups (+MILK/−MILK), and sows were either crated or loose housed (CRATE/LOOSE) in a 2 × 2 × 2 factorial design. Piglet mortality was higher in LS17 compared to LS14 (P < 0.01; OR = 2.0), higher in −MILK compared to +MILK (P = 0.01; OR = 1.2) and higher in LOOSE compared to CRATE (P = 0.02; OR = 1.8). This study showed that sow rearing of supernumerary piglets while supplying with milk replacer can increase piglet survival. It also showed that early mortality before piglets learned to drink milk replacer posed a challenge using this automatic milk replacer system. An interaction between access to milk replacer and the standardised litter size D1 affected litter weight (P < 0.01) and piglet weight day 28 (D28) (P = 0.03). The highest litter weight D28 was found in LS17 +MILK (P < 0.01) but with a lower individual piglet weight than in LS14 −MILK. Piglet weight D28 was higher in LS14 −MILK compared to LS17 regardless of access to milk replacer. Heterogeneity in piglet weight within litters D28 was larger in LS17 (P = 0.03) but could be reduced with +MILK in CRATE (P < 0.01). No effects were found on sow weight loss and feed intake (P > 0.05). In conclusion, the results showed that sows cannot rear the supernumerary piglets without further management interventions to reduce mortality. Supplying supernumerary piglets equal to the mean live-born litter size of hyper-prolific sows with milk replacer can from results of this study be an alternative strategy to the use of nurse sows.     

Nutrient utilisation,growth performance and blood metabolites in Murrah buffalo calves (Bubalus bubalis) divergently selected for residual feed intake

The aim of this study was to evaluate differences in efficiency of feed utilisation between buffalo calves with low and high residual feed intake (RFI) by comparing feed intake, nutrient digestibility, growth traits and blood metabolites. Eighteen male Murrah buffalo calves (aged 4–6 months; 70 ± 1.0 kg body weight) were fed ad libitum with a total mixed ration for 120 d. Based on linear regression models involving dry matter intake (DMI), average daily gain (ADG) and mid-test metabolic body size, calves were assigned into low and high RFI groups. The RFI varied from ?0.33 to +0.28 kg DM/d with an average RFI of ?0.14 and 0.14 kg DM/d in low and high RFI calves, respectively. Calves had a mean DMI of 1.9 and 2.4 kg/d and an ADG of 0.5 and 0.6 kg/d in low and high RFI groups, respectively. Low RFI calves ate 19.0% less DM each day and required significantly less metabolisable energy for maintenance compared with high RFI calves (12.5 vs. 16.7 MJ/d). Nutrient digestibility and nitrogen balance did not differ among low and high RFI calves. In more efficient animals (low RFI calves) higher (p < 0.05) plasma level of growth hormone, insulin-like growth factor-1 (IGF-1), triiodothyronine (T₃) and lower concentration of thyroxin hormone were detected. No significant differences in levels of insulin, hydroxyproline, plasma and urine creatinine, total protein and albumin between high and low RFI groups were found. Blood metabolites showed significant (p < 0.05) differences at initial and final stages of study in both groups. At final stage of study, RFI showed negative correlations with growth hormone, IGF-1, T₃, urine creatinine and albumin. Low RFI buffalo calves are more efficient in feed utilisation and the differences in blood metabolites are probably due to differences in feed intake and body metabolism.     

Divergence for residual feed intake of Holstein-Friesian cattle during growth did not affect production and reproduction during lactation

Residual feed intake (RFI) is the difference between actual and predicted dry matter intake (DMI) of individual animals. Recent studies with Holstein-Friesian calves have identified an ~20% difference in RFI during growth (calf RFI) and these groups remained divergent in RFI during lactation. The objective of the experiment described here was to determine if cows selected for divergent RFI as calves differed in milk production, reproduction or in the profiles of BW and body condition score (BCS) change during lactation, when grazing pasture. The cows used in the experiment (n=126) had an RFI of −0.88 and +0.75 kg DM intake/day for growth as calves (efficient and inefficient calf RFI groups, respectively) and were intensively grazed at four stocking rates (SR) of 2.2, 2.6, 3.1 and 3.6 cows/ha on self-contained farmlets, over 3 years. Each SR treatment had equal number of cows identified as low and high calf RFI, with 24, 28, 34 and 40/11 ha farmlet. The cows divergent for calf RFI were randomly allocated to each SR. Although SR affected production, calf RFI group (low or high) did not affect milk production, reproduction, BW, BCS or changes in these parameters throughout lactation. The most efficient animals (low calf RFI) lost similar BW and BCS as the least efficient (high calf RFI) immediately post-calving, and regained similar BW and BCS before their next calving. These results indicate that selection for RFI as calves to increase efficiency of feed utilisation did not negatively affect farm productivity variables (milk production, BCS, BW and reproduction) as adults when managed under an intensive pastoral grazing system.     

Isotopologue Profiling of Legionella pneumophila: ROLE OF SERINE AND GLUCOSE AS CARBON SUBSTRATES*

Legionella pneumophila (Lp) is commonly found in freshwater habitats but is also the causative agent of Legionnaires'' disease when infecting humans. Although various virulence factors have been reported, little is known about the nutrition and the metabolism of the bacterium. Here, we report the application of isotopologue profiling for analyzing the metabolism of L. pneumophila. Cultures of Lp were supplied with [U-¹³C₃]serine, [U-¹³C₆]glucose, or [1,2-¹³C₂]glucose. After growth, ¹³C enrichments and isotopologue patterns of protein-derived amino acids and poly-3-hydroxybutyrate were determined by mass spectrometry and/or NMR spectroscopy. The labeling patterns detected in the experiment with [U-¹³C₃]serine showed major carbon flux from serine to pyruvate and from pyruvate to acetyl-CoA, which serves as a precursor of poly-3-hydroxybutyrate or as a substrate of a complete citrate cycle with Si specificity of the citrate synthase. Minor carbon flux was observed between pyruvate and oxaloacetate/malate by carboxylation and decarboxylation, respectively. The apparent lack of label in Val, Ile, Leu, Pro, Phe, Met, Arg, and Tyr confirmed that L. pneumophila is auxotrophic for these amino acids. Experiments with [¹³C]glucose showed that the carbohydrate is also used as a substrate to feed the central metabolism. The specific labeling patterns due to [1,2-¹³C₂]glucose identified the Entner-Doudoroff pathway as the predominant route for glucose utilization. In line with these observations, a mutant lacking glucose-6-phosphate dehydrogenase (Δzwf) did not incorporate label from glucose at significant levels and was slowly outcompeted by the wild type strain in successive rounds of infection in Acanthamoeba castellanii, indicating the importance of this enzyme and of carbohydrate usage in general for the life cycle of Lp.