The aim of the study was to determine the influence of dietary phospholipid concentration on survival and development in sea bass (Dicentrarchus labrax) larvae. Larvae were fed from day 9 to day 40 post-hatch with an isoproteic and isolipidic formulated diet with graded phospholipid levels from 27 to 116 g/kg DM and different phospholipid:neutral lipid values. The best growth (32 mg at the end of the experiment) survival (73 %) and larval quality (only 2% of malformed larvae) were obtained in the larvae fed the diet containing 116 g phospholipid/kg DM (P < 0·05). These results were related to the amount of phosphatidylcholine and phosphatidylinositol included in this diet (35 and 16 g/kg respectively). Amylase, alkaline phosphatase and aminopeptidase N activities revealed a proper maturation of the digestive tract in the two groups fed the highest phospholipid levels. Regulation of lipase and phospholipase A2 by the relative amount of their substrate in the diet occurred mainly at the transcriptional level. The response of pancreatic lipase to dietary neutral lipid was not linear. As in mammals 200 g triacylglycerol/kg diet seems to represent a threshold level above which the response of pancreatic lipase is maximal. The response of phospholipase A2 to dietary phospholipid content was gradual and showed a great modulation range in expression. Sea bass larvae have more efficient capacity to utilize dietary phospholipid than neutral lipids. For the first time a compound diet sustaining good growth, survival and skeletal development has been formulated and can be used in total replacement of live prey in the feeding sequence of marine fish larvae.

Polyunsaturated fatty acids (FA) regulate genes involved in lipid metabolism. The effects of polyunsaturated FA on the transcription factor adipocyte determination and differentiation-dependent factor (ADD) 1 and fatty acid synthase (FAS) mRNA in differentiating porcine adipocytes were measured using a stromal vascular cell culture system. Porcine stromal vascular cells were isolated from subcutaneous adi-pose tissues and plated in Dulbecco's modified Eagle's medium (DMEM)–nutrient mixture F-12 Ham (F-12) plus fetal bovine serum (100 ml/l) for 24 h. Then cells were differentiated in DMEM–F12 plus insulin, hydrocortisone and transferrin without or with polyunsaturated FA at 6·25, 25·00 or 100·00 μm. The ADD1 mRNA was decreased by 100·00 μm-arachidonic acid, 6·25 to 100·00 μm-docosahexaenoic acid or cis-9,trans-11-conjugated linoleic acid. The polyunsaturated FA reduced the transcription rate of FAS, but not of ADD1. All three polyunsaturated FA accelerated degradation of ADD1 and FAS mRNA to reduce the abundance of ADD1 and FAS mRNA. Results also showed that polyunsaturated FA inhibit the ADD1 expression, not only of mRNA concentration, but also of mature ADD1 protein concentration, suggesting an overall reduction of ADD1 function by polyunsaturated FA. Our present experiments demonstrate that polyunsaturated FA regulate the gene expression of ADD1 and enzymes involved in lipid metabolism in porcine adipocytes.

The utilisation of essential amino acids (EAA) by the mammary gland of lactating dairy cows fed fresh forages was studied to provide basic information useful in designing strategies to increase the production of milk protein from pasture-fed dairy cows. The relationship between the flux of EAA in the whole body and their uptake by the mammary gland was determined in four cows in early lactation (length of time in milk 44 (SD 14·5) d) producing 21 (SD 4·0) kg milk/d. The cows were maintained in metabolism stalls and fed fresh perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) pasture ad libitum or restricted to 75 % ad libitum intake. The whole-body fluxes of amino acids (AA) were measured using an arterio-venous infusion of universally 13C-labelled AA. Whole-body fluxes of fourteen AA were estimated. Isotope dilution indicated that mammary utilisation accounted for one-third of the whole-body flux of EAA, with individual AA ranging between 17 and 35 %. Isoleucine, leucine, valine and lysine were the EAA with the greatest partitioning towards the mammary gland (up to 36 % of the whole-body flux), which could reflect a potentially limiting effect on milk protein synthesis. In the case of AA with low partitioning to the mammary gland (for example, histidine), it is suggested that non-mammary tissues may have priority over the mammary gland and therefore the supply of this AA may also limit milk protein synthesis.

Milk enriched in conjugated linoleic acid (CLA) was obtained from cows on pasture supplemented with full-fat rapeseeds (FFR; 2·26g cis 9, trans 11 (c9, t11)-CLA/100g fatty acid methyl esters) and full-fat soyabeans (1·83g c9, t11-CLA/100g fatty acid methyl esters). A control milk fat (1·69g c9, t11-CLA/100g fatty acid methyl esters) was obtained from cows fed on pasture only. The present study assessed the potency of the CLA-enriched milk fats to modulate biomarkers that had previously been observed to respond to c9, t11-CLA in the MCF-7 and SW480 cell lines. Cell numbers decreased (P<0·05) by up to 61 and 58% following the incubation of MCF-7 and SW480 cells, respectively, for 4d with milk fats (yielding CLA concentrations between 60·2 and 80·6μM). The FFR milk fat, containing the highest CLA content, increased (P<0·05) [14C]arachidonic acid (AA) uptake into the monoacylglycerol fraction of MCF-7 and SW480 cells while it decreased (P<0·05) uptake into the phospholipid fraction of the latter. This milk fat also decreased (P<0·05) [14C]AA conversion to prostaglandin (PG) E2 while increasing conversion to PGF2α in both cell lines. All milk-fat samples increased (P<0·05) lipid peroxidation as measured by 8-epi-PGF2α in both cell lines. In SW480 cells the milk-fat samples decreased (P<0·05) bcl-2 and cytosolic glutathione levels while increasing (P<0·05) membrane-associated annexin V levels. All milk-fat samples decreased (P<0·05) the expression of ras in SW480 cells. These data suggest that milk-fat CLA was effective at modulating synthetic CLA-responsive biomarkers.

Chicken muscle ribosomal protein S6 kinase (S6K1) has been recently characterised and its enzymic activity is regulated by the nutritional and hormonal (insulin) status in vivo. The regulation of S6K1 is still unknown in neonatal chicks. The present study aimed to compare the activation of S6K1 in early-feeding (EF) and 48 h-delayed-feeding (DF) chicks from hatching to 4 d of age. During post-hatching starvation, S6K1 activity remained at the basal level measured in the control-hatched chicks. The maximum S6K1 activity was recorded on the first day of feeding with an increase of about 2·5-fold in the EF and DF chicks (P<0·01). S6K1 activity was correlated with plasma insulin level, suggesting a probable insulin-dependent S6K1 activation. The feeding-induced increase in S6K1 activity was related to its Thr389 residue phosphorylation. A similar pattern for protein kinase B phosphorylation was observed, upstream from S6K1. The S6K1 pathway was stimulated to the same extent in the EF and DF chicks, which indicates that post-hatching starvation did not increase S6K1 activation. It is concluded that muscle S6K1 is activated as soon as food is available without improvement in the response of the S6K1 pathway after post-hatching starvation.

Lycopene, the main carotenoid found in tomatoes and tomato-based products, has been reported to be protective against several types of cancer. Assessment of changes in plasma concentration of carotenoids following ingestion of lycopene-rich food sources does not necessarily predict changes in lycopene concentration or distribution of its isomers in other body tissues. Our aim was to determine the relationship between concentrations of lycopene and other tomato carotenoids in human serum and body tissues after tomato-oleoresin supplementation. Tomato lycopene oleoresin (30 mg/d) or a placebo was administered for 1 to 7 weeks to seventy-five volunteers undergoing elective haemorrhoidectomy or peri-anal fistulotomy. Carotenoid concentration and isomer distribution in blood and in the surgically removed skin and adipose tissues was measured by HPLC. The serum concentration of lycopene increased after supplementation from 0·26 (sd 0·12) to 0·52 (sd 0·25) μmol/l (n 35; P<0·0001). In the placebo group (n 40), lycopene serum concentration did not change significantly. Serum lycopene concentration after treatment was 2·2-fold greater in the lycopene group than in the placebo group, a slightly higher ratio than that found in skin and adipose tissue (1·6- and 1·4-fold higher than the placebo, respectively). A significant correlation between serum and tissue concentrations was found for both β-carotene and lycopene in the placebo group, whereas in the lycopene-supplemented group the correlation between serum and tissues remained the same for β-carotene but for lycopene was weak. Lycopene supplementation did not significantly change the proportion of all-trans v. cis isomers in the serum and tissues, despite the fact that more than 90 % of the supplemented lycopene was in the all-trans form. These results show that tomato-oleoresin supplementation increases lycopene concentrations in serum and in adipose tissue and skin. The ability to increase lycopene levels in tissues is one of the prerequisites for using it as a food supplement with health benefits.

In the present study the effects of some C18 fatty acids on hepatic fatty acid metabolism have been compared. Male rats were fed cholesterol-free diets containing either C18:0, C18:1cis or C18:1trans isomers as the variables. In accordance with previous work, oleic acid in the diet caused an increase in cholesterol concentration in the liver and in the lipoprotein fraction of density (d; kg/l)<1·006. Oleic acid also reduced the triacylglycerol:cholesterol value in this fraction. Surprisingly, the C18:1trans isomers diet induced a decrease in the amount of cholesterol in total plasma as well as in the 1·019<d<1·063 lipoprotein fraction. Both oleic acid and C18:1trans isomers increased the concentration of triacylglycerols in the liver. The two C18:1 fatty acids differently influenced the hepatic activities of carnitine palmitoyltransferase-I and 3-hydroxy-acyl-CoA dehydrogenase; both enzymes were inhibited by C18:1trans isomers, while no change was induced by oleic acid. The activity of the citrate carrier was lower in the oleic acid- and C18:1trans isomers-fed rats, when compared with the rats fed stearic acid. No diet effects were seen for the activities of acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, citrate synthase and phosphofructokinase. The results are interpreted in that oleic acid raised liver triacylglycerol by reducing the secretion of it with the d<1·006 lipoprotein fraction whereas the C18:1trans isomers enhanced liver triacylglycerol by lowering the hepatic oxidation of fatty acids.

Plasmalogen is a subclass of phospholipids that is widely distributed in man and animals. Many physiological roles have been proposed for this lipid; however, there have been no reports on the intestinal absorption of plasmalogen. In the present study, we examined lymphatic absorption of plasmalogen after the duodenal infusion of emulsified brain phospholipids (BPL) containing plasmalogen (22 mol% of total phospholipids) and soyabean lecithin (SPL) (100 g emulsified phospholipid/l). Male Wistar rats with implanted cannulas in the mesenteric lymph duct and the duodenum were kept in a Bollman-type restraining cage, and were infused the emulsion after 1 d recovery with duodenal infusion of a glucose–NaCl solution. Lymphatic plasmalogen output was increased at 2–4 h after the switch to BPL emulsion, and peaked at 4–6 h. However, no increases were observed after SPL infusion. Lymphatic recovery of plasmalogen for 8 h was 198 nmol, which was 0·22 mol% of the total plasmalogen disappeared from the intestine. We did not detect any increases in long-chain fatty aldehydes, which are the degradation product of plasmalogen, either in the blood or the small intestine. We conclude that a small percentage but a significant amount of the plasmalogen was absorbed into the lymph.

Maternal nutrition and growth hormone (GH) treatment during early- to mid-pregnancy can each alter the subsequent growth and differentiation of muscle in progeny. We have investigated the effects of varying maternal nutrition and maternal treatment with porcine (p) GH during the second quarter of pregnancy in gilts on semitendinosus muscle cross-sectional area and fibre composition of progeny, and relationships between maternal and progeny measures and progeny muscularity. Fifty-three Large White×Landrace gilts, pregnant to Large White×Duroc boars, were fed either 2·2 kg (about 35 % ad libitum intake) or 3·0 kg commercial ration (13·5 MJ digestible energy, 150 g crude protein (N×6·25)/kg DM)/d and injected with 0, 4 or 8 mg pGH/d from day 25 to 50 of pregnancy, then all were fed 2·2 kg/d for the remainder of pregnancy. The higher maternal feed allowance from day 25 to 50 of pregnancy increased the densities of total and secondary fibres and the secondary:primary fibre ratio in semitendinosus muscles of their female progeny at 61 d of age postnatally. The densities of secondary and total muscle fibres in semitendinosus muscles of progeny were predicted by maternal weight before treatment and maternal plasma insulin-like growth factor-II during treatment. Maternal pGH treatment from day 25 to day 50 of pregnancy did not alter fibre densities, but increased the cross-sectional area of the semitendinosus muscle; this may be partially explained by increased maternal plasma glucose. Thus, maternal nutrition and pGH treatment during the second quarter of pregnancy in pigs independently alter muscle characteristics in progeny.

The present study was designed to determine the effects of various levels of capsaicin (CAP) on endurance capacity in forty-nine male Sprague–Dawley rats, aged 4 weeks, which were assigned to four groups. Rats were given orally either control (0) or 6, 10 or 15 mg CAP/kg body weight 2 h before exercise by stomach intubations using a round-ended needle. The rats in each group were divided into two subgroups for resting or swimming exercise. Swimming exercise was performed with a weight corresponding to 3 % body weight attached to the tail, and endurance capacity was evaluated by swimming time to exhaustion. The highest dose (15 mg/kg) of CAP significantly (P < 0·05) increased endurance performance time and caused plasma non-esterified fatty acid to rise significantly by about 1·4-fold compared with that of non-CAP treated rats at exhaustion (P < 0·05). The highest dose of CAP had no effect on liver and gastrocnemius muscle glycogen (white and red) in resting rats, but significantly increased glycogen contents of both muscles at exhaustion (P < 0·05). At rest, plasma noradrenalin levels of the rats receiving the highest dose were greater than that of non-CAP-treated rats and remained greater until exhaustion. The effects of CAP on endurance capacity have received little attention and have conveyed conflicting impressions. Kim et al. (1997) failed to show the maximal effect of 10 mg/kg doses of CAP on swimming endurance time in mice. The influences of various doses of CAP on endurance capacity were still unclear. Matsuo et al. (1996) reported that the intake of CAP have little sparing effect on glycogen in the liver and soleus muscles at rest and during exercise in rats previously fed a CAP-containing diet ad libitum for 1 week. Our present results suggest more than the highest dose of CAP (15 mg/kg) can cause the increase of endurance capacity, which might be induced through the sparing of muscle glycogen and the rise of non-esterfied fatty acids following the increase of circulating catecholamine.

Improvement in the nutritional quality of Bangladeshi rice-based diets is sought through increasing the amounts of vegetables, fish and legumes consumed. The aim of the present study was to compare the effects of rice-based diets on selected parameters of Ca and P availability and retention in young, growing rats. The study was designed as a randomised balance trial with five diets, eight animals per diet, and two balance periods of 1 week each. Apart from diet 1, which was a pure rice diet, the other four diets were composite diets and included the leafy vegetable, amaranth leaves (Amaranthus gangeticus), the small fish, mola (Amblypharyngodon mola), and lentils (Lens culinaris) in different amounts to simulate the average rural rice-based diet, the recommended diet, the recommended diet diluted with starch, and the recommended diet excluding amaranth leaves. The inclusion of amaranth leaves, mola and lentils significantly improved N and growth retention in the rats compared with the pure rice diet. However, a minor addition of amaranth (0·66 g/100 g DM) significantly reduced the fractional Ca absorption and retention. Femur bone mass and Ca and P densities were significantly lower in the rats fed the diets that included amaranth leaves. The observed inhibitory effect of the amaranth leaves on Ca absorption and utilisation was probably due to the oxalate content. It is concluded that the formulation of a recommended diet cannot be based only on nutrient content values of individual food components due to interactions between nutrients and anti-nutrients in the diet.

Phytosterols are plant sterols found in foods such as oils, nuts and vegetables. Phytosterols, in the same way as cholesterol, contain a double bond and are susceptible to oxidation. The objective of the present study was to assess the potential toxic effects of β-sitosterol oxides on U937 cells. The effects of increasing concentrations (0-120 μM) of β-sitosterol oxides on cellular cytotoxicity, apoptosis, anti-oxidant status and genotoxicity was assessed over 12, 24 and 48h exposure periods. Following 12h, the viability of cells treated with 120 μM-β-sitosterol oxides was reduced to 51·7% relative to control. At 24 and 48 h, both 60 and 120 μM-β-sitosterol oxides caused a significant decrease in cell viability. For comparison, a decrease in viability of cells treated with a cholesterol oxide, 7β-hydroxycholesterol (7β-OH, 30 μM), was evident at 24 h. An increase in apoptotic cells, assessed using Hoechst 33342, indicates that the mode of cell death in U937 cells following exposure to 7β-OH (30 μM) and β-sitosterol oxides (60 and 120 μM) was by apoptosis. The increase in apoptotic cells after 12h following treatment with 120 μM-β-sitosterol oxides was accompanied by a decrease in cellular glutathione. Similarly, 7β-OH (30 μM) treatment resulted in decreased glutathione at 12 h. Catalase activity was not affected by any of the treatments. β-Sitosterol oxides had no genotoxic effects on U937 and V79 cells as assessed by the comet and sister chromatid exchange assays respectively. In general, the results indicate that thermally oxidised derivatives of β-sitosterol demonstrate similar biological effects as 7β-OH in U937 cells, but at higher concentrations.

Alkalizing beverages are highly effective in preventing the recurrence of calcium oxalate (Ox), uric acid and cystine lithiasis. The aim of the present study was to evaluate the influence of grapefruit-juice and apple-juice consumption on the excretion of urinary variables and the risk of crystallization in comparison with orange juice. All investigations were carried out on nine healthy female subjects without any history of stone formation and aged 26–35 years. Each juice was tested in a 5 d study. During the study, the subjects received a standardized diet. Fluid intake of 2·75 litres was composed of 2·25 litres neutral mineral water, 0·4 litre coffee and 0·1 litre milk. On the fourth and fifth day 0·5 litre mineral water was partly substituted by 0·5 or 1·0 litre juice under investigation respectively. The influence on urinary variables was evaluated in 24 h urine samples. In addition, the BONN risk index of CaOx, relative supersaturation (RS)CaOx crystallization was determined. Due to an increased pH value and an increased citric acid excretion after consumption of each juice, the RSCaOx decreased statistically significantly (P<0·05) for grapefruit juice, but not significantly for orange and apple juice. The BONN risk index yielded a distinct decrease in the crystallization risk. We showed that both grapefruit juice and apple juice reduce the risk of CaOx stone formation at a magnitude comparable with the effects obtained from orange juice.

The aim of the present study was to investigate the influence of dietary-fibre (DF)-rich barley-based diets on bile acids (BA) and neutral sterols (NS) in the intestinal tract of rats. For this purpose, young male Wistar rats (n 50; ten per group) weighing about 67g were fed either a barley-free diet (control group) or diets containing 500g barley meal extrudates/kg or a barley meal–Novelose mixture (groups A–D) for 6 weeks. These barley products contained 7–24g resistant starch/100g and 7–12g (1→3),(1→4)-β-glucan/100g. More steroids were transported towards the lower parts of the intestinal tract when higher concentrations of macromolecular DF were present in the diets (P<0·001). Tauroconjugated and primary BA dominated in the contents of the small intestine. Intense enzymic conversion of BA occurred in the caecum and colon. The fermentation of DF affected indirectly the amount of formed secondary BA. The main BA present in the caecal contents were muricholic acids, hyodeoxycholic acid and cholic acid. The BA spectrum in the colonic contents was different from that in the caecum. A higher concentration of NS appeared in the intestinal contents of the groups fed the barley-based diets than in the controls (P<0·005). The microbial conversion of cholesterol to coprostanol, cholestanone and coprostanone was influenced by the amount and composition of the DF in the gut. DF in the diet may affect the concentration and spectrum of steroids in the intestinal tract. The results are relevant for the discussion of mechanisms behind the cholesterol-lowering effects of DF.

In rats, maternal anaemia during pregnancy causes hypertension in the adult offspring, although the mechanism is unknown. The present study investigated the renal morphology of adult rats born to mothers who were Fe-deficient during pregnancy. Rats were fed either a control (153 mg Fe/kg diet, n 7) or low-Fe (3 mg/kg diet, n 6) diet from 1 week before mating and throughout gestation. At delivery, the Fe-restricted (IR) mothers were anaemic; the IR pups were also anaemic and growth-retarded at 2 d of age. At 3 and 16 months, systolic blood pressure in the IR offspring (163 (sem 4) and 151 (sem 4) mmHg respectively, n 13) was greater than in control animals (145 (sem 3) and 119 (sem 4) mmHg respectively, n 15, P<0·05). At post mortem at 18 months, there was no difference in kidney weight between treatment groups, although relative kidney weight as a fraction of body weight in the IR offspring was greater than in control animals (P<0·05). Glomerular number was lower in the IR offspring (11·4 (sem 1·1) per 4mm2, n 13) compared with control rats (14·8 (sem 0·7), n 15, P<0·05). Maternal treatment had no effect on glomerular size, but overall, female rats had smaller and more numerous glomeruli per unit area than male rats. When all animals were considered, inverse relationships were observed between glomerular number and glomerular size (r−0·73, n 28, P<0·05), and glomerular number and systolic blood pressure at both 3 months (r−0·42, n 28, P<0·05) and 16 months of age (r−0·64, n 28, P<0·05). Therefore, in rats, maternal Fe restriction causes hypertension in the adult offspring that may be due, in part, to a deficit in nephron number.

The prevention of arterial thrombotic diseases has a high priority in developed countries. An inappropriate diet may be an important risk factor for thrombotic events. The daily intake of an anti-thrombotic diet may offer a convenient and effective way of prevention. The aim of the present study was to test tomato extracts for anti-thrombotic effects and to identify those varieties that have such an effect. A shear-induced platelet-function test (haemostatometry) was used to test anti-thrombotic potential in vitro. Extracts from those tomato varieties that showed a significant anti-thrombotic activity in vitro were further assessed in vivo, using a laser-induced thrombosis test in mice. One tomato variety (KG99-4) showed significant anti-thrombotic activity both in vitro and in vivo. KG99-4 inhibited not only platelet-rich thrombus formation but also had a thrombolytic effect. It is concluded that haemostatometry can detect and classify the anti-thrombotic potential of fruits and vegetables and offers a simple way of screening for such effects.

The present study was designed to evaluate the differential effects of dietary glucose, lactose and starch on small-intestinal morphology, organ weights, pH of chyme and haptoglobin levels in blood plasma of weaned piglets. It was hypothesised that lactose consumption would ameliorate the weaning-induced decrease in gut integrity. A total of forty-two barrows were used. Piglets were weaned at 27 (sd 0·8) d of age and weighed 8·0 (sd 0·51) kg. On the day before weaning (day −1) all pigs were blocked according to body weight and randomly assigned to seven groups (n 6 per group). The groups differed in diet and day of dissection. On the day of weaning, dissection was performed on one group of six piglets. The remaining groups were fed one of three experimental diets in which glucose, lactose or starch had been iso-energetically exchanged, supplying 24% dietary energy. The piglets received a liquid diet (air-dry meal:water of 1:2, w/w). The piglets were given access to a maximum of dietary energy in order to prevent confounding between feed intake and villus architecture. The piglets were dissected and sampled on days 0, 3, or 10 post-weaning. The results show that the carbohydrate source did not affect growth performance, organ weights, villus architecture, pH of chyme and plasma haptoglobin level. The weaning transition resulted in decreased villus height and increased haptoglobin levels. In the contents of the caecum and large intestine, the pH decreased after weaning. It is concluded that at least under conditions of similar feed intake and low infectious pressure, dietary lactose does not ameliorate the weaning-induced compromise of small-intestinal integrity when compared with either glucose or starch.

The efficiency of myristic acid (14:0) as a feed additive to suppress CH4 emissions of ruminants was evaluated under different dietary conditions. Six sheep were subjected to a 6 × 6 Latin square arrangement. A supplement of non-esterified 14: 0 (50 g/kg DM) was added to two basal diets differing in their forage:concentrate values (1:1/5 and 1: 0/5), which were adjusted to dietary Ca contents of 4/2 and 9/0 g/ kg DM, respectively. Comparisons were made with the unsupplemented basal diets (4/2 g Ca/kg DM). The 14:0 supplementation decreased (P < 0/001) total tract CH4 release depending on basal diet type (interaction, P < 0/001) and dietary Ca level (P < 0/05, post hoc test). In the concentrate-based diet, 14:0 suppressed CH4 emission by 58 and 47% with 4/2 and 9/0 g Ca/kg DM, respectively. The 14:0 effect was lower (22%) in the forage-based diet and became insignificant with additional Ca. Myristic acid inhibited (P < 0/05) rumen archaea without significantly altering proportions of individual methanogen orders. Ciliate protozoa concentration was decreased (P < 0/05, post hoc test) by 14:0 only in combination with 9/0 g Ca/kg DM. Rumen fluid NH3 concentration and acetate:pro-pionate were decreased (P < 0/05) and water consumption was lower (P < 0/01) with 14:0. The use of 14:0 had no clear effects on total tract organic matter and fibre digestion; this further illustrates that the suppressed methanogenesis resulted from direct effects against methanogens. The present study demonstrated that 14:0 is a potent CH4 inhibitor but, to be effective in CH4 mitigation feeding strategies, interactions with other diet ingredients have to be considered.

Four studies were conducted to compare the effect of four indigestible markers (LiCoEDTA, Yb-acetate, Cr-mordanted straw and indigestible neutral-detergent fibre (INDF)) and three marker systems on the flow of digesta entering the omasal canal of lactating dairy cows. Samples of digesta aspirated from the omasal canal were pooled and separated using filtration and high-speed centrifugation into three fractions defined as the liquid phase, small particulate and large particulate matter. Co was primarily associated with the liquid phase, Yb was concentrated in small particulate matter, whilst Cr and INDF were associated with large particles. Digesta flow was calculated based on single markers or using the reconstitution system based on combinations of two (Co + Yb, Co + Cr and Co + INDF) or three markers (Co + Yb + Cr and Co + Yb + INDF). Use of single markers resulted in large differences between estimates of organic matter (OM) flow entering the omasal canal suggesting that samples were not representative of true digesta. Digesta appeared to consist of at least three phases that tended to separate during sampling. OM was concentrated in particulate matter, whilst the liquid phase consisted mainly of volatile fatty acids and inorganic matter. Yb was intimately associated with nitrogenous compounds, whereas Cr and INDF were concentrated in fibrous material. Current data indicated that marker systems based on Yb in combination with Cr or INDF are required for the accurate determination of OM, N and neutral-detergent fibre flow. In cases where the flow of water-soluble nutrients entering the omasal canal is also required, the marker system should also include Co.

Cis 9, trans 11 (c 9, t11)-18: 2 and trans 10, cis 12 (t10, c12)-18: 2 are the major conjugated linoleic acid (CLA) isomers in dietary supplements which reduce milk fat content in nursing women. The present study evaluated the effects of each CLA isomer or vaccenic acid on body composition and tissue fatty acids during lactation in mice. Dams were fed 30 g rapeseed oil (control)/kg diet or 20 g control plus 10 g 18: 0, trans 11–18: 1 (t11–18: 1), c 9, t11–18: 2, or t10, c12–18: 2. Dietary t10, c12–18: 2 reduced food intake by 18 % and carcass fat weight of the dams by 49 % compared with the other treatments. Milk fat percentage ranked by treatment was 18: 0>t11–18: 1=c 9, t11–18: 2>t10, c12–18: 2. The sum of saturated 12: 0 to 16: 0 in milk fat was lower when c 9, t11–18: 2 was fed compared with the control, 18: 0, or t11–18: 1 treatments. Dietary t10, c12–18: 2 caused further reductions in milk fat 12: 0 to 16: 0. The proportion of CLA isomers was 3-fold greater in milk fat than in the carcasses of the dams. The pups nursing from the dams fed t10, c12–18: 2 had the lowest body weights and carcass fat, protein, and ash contents. Nursing from the dams fed c 9, t11–18: 2 also resulted in lower carcass fat compared with the 18: 0 or t11–18: 1 treatments. The ratios of cis 9–16: 1:16: 0 or cis 9–18: 1:18: 0, proxies for Δ9-desaturase activity, were markedly lower in the carcasses of the dams and pups fed t10, c12–18: 2. The ratio of 20: 4n-6:18: 2n-6, a proxy for Δ6- and Δ5-desaturase and elongase activity, in the liver of the dams and pups fed t10, c12–18: 2 also was lower. Dietary t11–18: 1 enhanced the content of c 9, t11–18: 2 in milk fat and carcasses. As in previous studies, the reduction in food intake by t10, c12–18: 2 could not entirely account for the marked decrease in carcass fat content and milk fat concentration. T10, c12–18: 2 probably had a negative effect on Δ9-desaturase and mammary de novo fatty acid synthesis. Although these effects need to be confirmed in lactating women, the results suggest that the consumption of supplements containing t10, c12–18: 2 should be avoided during the nursing period.