Development of a conversion model between mechanical and electrical vestibular stimuli.

The vestibular end-organs encode for linear and angular head accelerations in space contributing to our internal representation of self-motion. Activation of the vestibular system with transmastoid electrical current has recently grown in popularity; however, a direct relationship between electrically evoked and mechanically evoked vestibular responses remains elusive in humans. We have developed and tested a mechanical-to-electrical vestibular stimulus conversion model incorporating physiological activation of primary vestibular afferents identified in nonhuman primates. We compared ocular torsional responses between mechanical (chair rotation) and model-derived electrical (binaural-bipolar) stimuli in separate experiments for an angular velocity step change (±10 deg/s over 1 s, ±4-mA peak amplitude; n = 10) and multisine angular velocities (±10 deg/s, 9.7 mA peak to peak, 0.05-1 Hz; n = 5), respectively. Perception of whole body rotation (n = 18) to our step-change stimuli was also evaluated. Ocular torsional slow-phase velocity responses between stimulation types were similar (paired two one-sided tests of equivalence: multiple P < 0.002; one-sample t test: P = 0.178) and correlated (Pearson's coefficient: multiple P < 0.001). Bootstrap analysis of perceived angular velocity likewise showed similarity in perceptual decay dynamics. These data suggest that central processing between stimuli was similar, and our vestibular stimulus conversion model with a conversion factor of ∼0.4 mA per deg/s for an angular velocity step change can generate electrical stimuli that replicates dynamic vestibular activation elicited by mechanical whole body rotations. This proposed vestibular conversion model represents an initial framework for using electrical stimuli to generate mechanically equivalent activation of primary vestibular afferents for use in biomedical applications and immersive reality technologies.NEW & NOTEWORTHY With the growing popularity of electrical vestibular stimulation in biomedical and immersive reality applications, a direct conversion model between electrical and mechanical vestibular stimuli is needed. We developed a model to generate electrical stimuli mimicking the physiological activation of vestibular afferents evoked by mechanical rotations. Ocular and perceptual responses evoked by mechanical and model-derived electrical stimuli were similar, thus providing a critical first step toward generation of electrically induced vestibular responses that have a realistic mechanical equivalent.

Effect of slaughter age and feeding system on the neutral and polar lipid composition of horse meat.

This study was undertaken to provide a thorough analysis of the neutral lipid (NL) and polar lipid (PL) fractions of horse meat that included the content and distribution of acyl and alkenyl moieties in foals under different rearing conditions. Two groups of crossbred horses were studied; the first group was selected from suckling foals produced under grazing conditions and slaughtered at 4 months of age (n=8), and the second group was selected from concentrate-finished foals and slaughtered at 12 months of age (n=7). There were significant differences related to the age and feeding practices of foals which affected the intramuscular (IM) fat content and the fatty acid (FA) composition of NL and PL fractions. Samples from suckling foals were leaner and provided the highest content of methylation products from the plasmalogenic lipids, and total and n-3 polyunsaturated fatty acid (PUFA). By contrast, the meat from concentrate-finished foals had a higher IM fat level resulting in a greater accumulation of 16:0 and total monounsaturated FAs in the NL fraction, whereas the muscle PL fraction retained a similar FA composition between both groups. Linolenic acid was preferentially deposited in the NL fraction, but linoleic acid and the long-chain n-3 and n-6 PUFAs were incorporated into the PL fraction where they served as cell membrane constituents and in eicosanoid formation.

Retention of n-3 polyunsaturated fatty acids in trimmed loin and belly is independent of timing of feeding ground flaxseed to growing-finishing female pigs.

A serial slaughter study, involving 45 individually housed Yorkshire female pigs, was conducted to evaluate the impact of feeding diets containing ground flaxseed (FS) during either the grower or late finisher phase on the incorporation of α-linolenic acid (18:3n-3) and n-3 highly unsaturated fatty acid metabolites (n-3 HUFA; all n-3 PUFA excluding 18:3n-3) in trimmed loin (longissimus dorsi) and belly (cross-section cut). Growth performance, carcass characteristics, and pork quality were also monitored. The three feeding regimens were 1) feeding a diet containing 10% FS between 25 and 50 kg BW, followed by FS-free diets (low n-3 PUFA content) until 110 kg BW (FS early, FSE; n = 16), 2) feeding no FS diets between 25 and 85 kg BW, followed by a diet containing 6% FS until 110 kg BW (FS late, FSL; n = 17), and 3) feeding FS-free diets between 25 and 110 kg BW (CON; n = 8). Pigs were assigned to 1 of 3 target slaughter weights for determining whole nutrient retention: 50 kg (n = 4 and 5 for FSE and FSL, respectively), 85 kg (n = 4 for FSE and FSL), and 110 kg (n = 8 pigs for FSE, FSL, and CON). An additional 4 pigs were slaughtered to determine initial body composition at 25 kg BW. Pigs on treatments FSE and FSL consumed equal cumulative amounts of FS (5.1 vs. 5.2 kg). Fatty acid content was expressed as milligrams per 100 g of fresh tissue. No treatment effect was observed for growth performance, body composition, carcass characteristics, loin meat quality, and fat content in the loin and belly samples. In the loin, the content of 18:3n-3 at 110 kg BW was greater for FSL than FSE and CON (P < 0.01; 143, 76.4, and 37 mg/100 g, respectively), whereas the contents of 18:3n-3 in the belly were greater for both FSL and FSE than CON (752, 667, and 207 mg/100 g for FSL, FSE, and CON, respectively). Within tissues, the content of n-3 HUFA was similar for FSL and FSE, and both were greater (P < 0.01) than CON for loin (41.7, 30.3, and 17.9 mg/100 g, respectively) and belly (168, 179, and 71.2 mg/100 g, respectively), except for docosahexaenoic acid (22:6n-3) in the loin. Feeding FS tended to reduce the content of arachidonic acid (20:4n-6) and adrenic acid (22:4n-6; P < 0.10) in the loin and belly. In the belly but not in the loin, feeding FS reduced the content of total SFA (P = 0.05) and tended to reduce the content of the sum of MUFA (P = 0.09). Within the loin and belly, the ratio of n-6 to n-3 PUFA and the content of n-3 HUFA were similar for FSE and FSL, with the exception of 18:3n-3 and 20:4n-6 in the loin, for which contents were greater for FSL than FSE (P < 0.05). These results indicate that providing modest amounts of FS leads to a substantial enrichment of 18:3n-3 and n-3 HUFA in pork products. The enrichment of n-3 HUFA appears to be independent of timing of feeding FS, providing flexibility as to when n-3 PUFA can be fed to generate n-3 PUFA-enriched pork products.

Ileal flows and apparent ileal digestibility of fatty acids in growing gilts fed flaxseed containing diets.

An experiment was conducted to quantify the ileal flow and apparent ileal digestibility (AID) of fatty acids (FA) in growing gilts fed corn, wheat, and soybean meal based diets without (CON) or with ground flaxseed (FS). A total of 20 healthy purebred Yorkshire female pigs, weighing approximately 25 kg BW, were allotted to 1 of 3 feeding regimens: R1 (n = 5 pigs), feeding a diet containing 10% FS between 25 and 50 kg BW and CON diet thereafter, R2 (n = 10 pigs), feeding CON diet between 25 and 85 kg BW and a diet containing 6% FS thereafter, and R3 (n = 5 pigs), feeding CON diet between 25 and 110 kg BW. Titanium dioxide was used as an indigestible marker to assess AID and ileal flows of crude fat and FA. At 110 kg BW, pigs were slaughtered and representative digesta samples were obtained from the distal ileum. Ileal flows and AID of crude fat and individual FA did not differ (P > 0.10) between R1 and R3, and therefore, results from these 2 feeding regimens were combined to give 2 dietary treatments (CON and FS). There were no treatment effects on AID of crude fat and the sum of all FA, SFA, or MUFA. However, the AID of individual SFA decreased with chain length (linear; P < 0.05) for both FS and CON. The AID of myristic acid (14:0), individual trans-18:1 FA (6t-8t-18:1 to 12t-18:1), myristoleic acid (9c-14:1), and palmitoleic acid (9c-16:1) were greater for CON than FS (P < 0.05) whereas no diet effect was observed for the AID of linoleic acid (18:2n-6; 80.2 and 86.1% for FS and CON, respectively) and α-linolenic acid (18:3n-3; 86.7 and 89.8% for FS and CON, respectively). Ileal flows of rumenic acid (9c11t-CLA), n-3 PUFA, and highly unsaturated FA (HUFA; arachidonic, eicosatrienoic, eicosapentaenoic, docosapentaenoic, and docosahexaenoic acids) exceeded their intakes, indicating net appearance of these FA in the upper gut of the pig. It remains to be determined whether enteric microbiota can elongate and desaturate 18:2n-6 and 18:3n-3 and isomerize 18:2n-6. The contribution of endogenous FA losses from the host to the ileal flow of these FA should also be considered. Further studies are needed to quantify production of CLA isomers and PUFA in the small intestine of pigs, specifically the n-3 HUFA, and to assess their contribution to the FA supply of the host.

The labile lipid fraction of meat: from perceived disease and waste to health and opportunity.

The fatty acid composition of beef and pork has been stigmatized due to their relationships with several diseases from cardiovascular disease to cancer. Meat lipids are, however, one of the few components of meat that can be modified in content and composition, and can present opportunities for value added production and health promotion. Until regulations and policies are in place to define requirements for fatty acid enrichment, however, the process remains relatively academic. Once practical goals are in place for fatty acid enrichment in meat, both theory and practice need to converge for successful production of fatty acid enriched meat. The present review covers aspects of policy in Canada, and requirements for research networks to respond to theoretical and practical challenges associated with production of fatty acid enriched meat. Finally, needs for education and marketing are outlined which must be in place to truly realize a transition of meat lipids from perceived disease and waste to health and opportunity.

Evaluation of rumen fatty acid hydrogenation intermediates and differences in bacterial communities after feeding wheat- or corn-based dried distillers grains to feedlot cattle.

The effect of partially replacing rolled barley (86.6% of control diet) with 20% wheat dried distillers grains plus solubles (DDGS), 40% wheat DDGS, 20% corn DDGS, or 40% corn DDGS (dietary DM basis) on rumen fluid fatty acid (FA) composition and some rumen bacterial communities was evaluated using 100 steers (20 per treatment). Wheat DDGS increased the 11t- to 10t-18:1 ratio (P < 0.05) in rumen fluid and there was evidence that the conversion of trans-18:1 to 18:0 was reduced in the control and wheat DDGS diets but not in the corn DDGS diet. Bacterial community profiles obtained using denaturing gradient gel electrophoresis and evaluated by Pearson correlation similarity matrices were not consistent for diet and, therefore, these could not be linked to different specific rumen FA. This inconsistency may be related to the nature of diets fed (dominant effect of barley), limited change in dietary composition as the result of DDGS inclusion, large animal-to-animal variation, and possibly additional stress as a result of transport just before slaughter. Ruminal densities of a key fiber-digesting bacteria specie that produces 11t-18:1 from linoleic and linolenic acids (Butyrivibrio fibrisolvens), and a lactate producer originally thought responsible for production of 10t,12c-18:2 (Megasphaera elsdenii) were not influenced by diet (P > 0.05).

The effects of feeding flaxseed to beef cows given forage based diets on fatty acids of longissimus thoracis muscle and backfat.

This study was conducted to investigate changes in fatty acid profiles of beef cows fed grass hay or barley silage based diets, with or without flaxseed supplementation. Both flaxseed and hay feeding increased levels of α-linolenic acid (LNA; 18:3n-3) in longissimus thoracis and backfat (P<0.001). A forage type by flaxseed level interaction was observed for most LNA biohydrogenation intermediates (P<0.05) that indicated feeding hay combined with flaxseed led to the greatest levels of total conjugated linolenic acid, total conjugated linoleic acid, total non-conjugated dienes and total trans-18:1. Predominant biohydrogenation intermediates included t11,c15-18:2, rumenic acid (c9,t11-18:2) and vaccenic acid (t11-18:1).

Extent of spontaneous motor recovery after traumatic cervical sensorimotor complete spinal cord injury.

STUDY DESIGN: Retrospective, longitudinal analysis of motor recovery data from individuals with cervical (C4-C7) sensorimotor complete spinal cord injury (SCI) according to the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI). OBJECTIVES: To analyze the extent and patterns of spontaneous motor recovery over the first year after traumatic cervical sensorimotor complete SCI. METHODS: Datasets from the European multicenter study about SCI (EMSCI) and the Sygen randomized clinical trial were examined for conversion of American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade, change in upper extremity motor score (UEMS) or motor level, as well as relationships between these measures. RESULTS: There were no overall differences between the EMSCI and Sygen datasets in motor recovery patterns. After 1 year, up to 70% of subjects spontaneously recovered at least one motor level, but only 30% recovered two or more motor levels, with lesser values at intermediate time points. AIS grade conversion did not significantly influence motor level changes. At 1 year, the average spontaneous improvement in bilateral UEMS was 10-11 motor points. There was only moderate relationship between a change in UEMS and a change in cervical motor level (r(2)=0.30, P<0.05). Regardless of initial cervical motor level, most individuals recover a similar number of motor points or motor levels. CONCLUSION: Careful tracking of cervical motor recovery outcomes may provide the necessary sensitivity and accuracy to reliably detect a subtle, but meaningful treatment effect after sensorimotor complete cervical SCI. The distribution of the UEMS change may be more important functionally than the total UEMS recovered.

Length of concentrate finishing affects the fatty acid composition of grass-fed and genetically lean beef: an emphasis on trans-18:1 and conjugated linoleic acid profiles.

Intensively finishing cattle on a high-grain diet is generally used to enhance marbling, whereas extensively finishing on grass is known to provide improved muscle fatty acid profiles. The objective of this study was to evaluate to what extent intensive concentrate finishing (0, 1 or 2 months) can be combined with forage feeding without negatively affecting the fatty acid profile of genetically lean animals. Bulls from the 'Asturiana de los Valles' breed were reared under grazing conditions with/without final finishing on a barley-based concentrate: 0 months (control; n=7), 1 month (n=10) and 2 months (n=7). Yearling bulls were slaughtered commercially at an average live weight of 516±9.8 kg. Increasing the finishing time on concentrate significantly increased the saturated and monounsaturated fatty acids, whereas polyunsaturated fatty acids (PUFAs) tended to decrease and it was not possible to increase the long-chain PUFA content in muscle tissue of this breed. An increase was observed for total trans-18:1 (average 5.5% with grain v. 3.7% for grass). The 11t-18:1/10t-18:1 ratio was significantly higher in grass-fed (average 8.1) compared with grain-finished animals (average 1.1). Grass or limited concentrate finishing reduced the n-6/n-3 ratio in muscle tissue (average 3.6 for 0 and 1 month, and 4.9 for 2 months on grain finishing). The beef was within or close to the recommended values for human consumption (i.e. polyunsaturated/saturated>0.45, n-6/n-3<4.0), and total trans-FA content was low. However, finishing increased the content of undesirable trans-18:1 and conjugated linoleic acid isomers, particularly after 2 months, whereas grass finishing was judged to provide a healthier beef fatty acid profile.

Feeding wheat dried distillers grains with solubles improves beef trans and conjugated linoleic acid profiles.

In western Canada, ethanol is produced mainly from wheat. As the demand for wheat increases, so do grain prices, which in turn creates incentives for feeding reduced-cost distillers coproducts to livestock. Substitution of wheat dried distillers grains plus solubles (DDGS) for barley grain may also create opportunities for enhancing beef fatty acid profiles because reducing starch concomitantly increases dietary fiber and oil and may shift PUFA biohydrogenation toward a healthier trans and CLA profile. To study this potential, heifers were fed diets containing 0, 20, 40, or 60% wheat DDGS (DM basis) substituted for rolled barley (n = 24; 133-d finishing period). Adding DDGS increased dietary oil (from 1.9 to 3.7%), but dietary fatty acid compositions remained consistent. Feeding increasing amounts of DDGS linearly decreased total diaphragm fatty acids on a milligram per gram basis (P = 0.031). For both brisket fat and diaphragm, feeding increasing amounts of DDGS caused linear increases in percentages of 18:2n-6 (P = 0.001) and total n-6 fatty acids (P = 0.001) but did not change the concentrations of individual or total n-3 fatty acids. Feeding increasing amounts of DDGS did not change the content of total trans MUFA in either brisket fat or diaphragm but led to linear decreases in 10t-18:1 (P = 0.033, brisket fat; P = 0.004, diaphragm) and increases in 11t-18:1 (P = 0.005, brisket fat; P = 0.003, diaphragm). Feeding increasing amounts of DDGS also caused a linear increase in 9c11t-18:2 (P = 0.044, brisket fat; P = 0.023, diaphragm) and total CLA (P = 0.086, brisket fat; P = 0.039, diaphragm). Overall, feeding DDGS enhanced the fatty acid composition of beef by decreasing 10t-18:1 while increasing the major CLA isomer (9c,11t-18:2) and its precursor 11t-18:1.

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production.

It was hypothesized that differences in starch degradability account for observed differences in rumen vaccenic acid (t11-18:1) and milk rumenic acid (RA) concentrations. To test this hypothesis, starch degradability was varied through grain source and by processing. Eight Holstein cows in mid-lactation were assigned to two 4 × 4 Latin squares with four 21-day periods and four diets: dry rolled barley, ground barley, dry rolled corn and ground corn. Diets contained similar starch content and were supplemented with whole sunflower seed to provide similar total polyunsaturated fatty acid (PUFA) (18:2n-6 + 18:3n-3) contents. Forage/concentrate ratios of all diets were 42 : 58. Rumen, plasma and milk samples were collected in the third week of each period. In situ degradation rates (%/h) for rolled corn, ground corn, rolled barley and ground barley were 5.4, 8.9, 17.0 and 19.4, respectively, for dry matter (DM) and 6.3, 10.8, 25.3 and 43.8, respectively, for starch. DM intakes were greater for corn-based diets (CBD) than for barley-based diets (BBD) with no difference between rolled and ground diets. Daily minimum rumen pH was less (5.2 v. 5.5) and pH duration <5.8 (h/d) was greater (7.4 v. 4.3) for BBD than for CBD. Milk fat content and yield were less for BBD than for CBD with greater values observed for rolling compared with grinding. Variability in milk fat yield was strongly related (R2 = 0.55; P < 0.01) to total starch intake (45%) and milk c9t11-CLA (10%) and none of the t-18:1 isomers or CLA isomers that are typically associated with milk fat depression entered the model. The concentrations (%) of t10-18:1 and t11-18:1 were greater for BBD than for CBD in rumen contents (t10-18:1, 3.5 v. 1.3; t11-18:1, 3.2 v. 1.9), plasma (t10-18:1, 1.2 v. 0.2; t11-18:1, 0.97 v. 0.58) and milk (t10-18:1, 3.8 v. 1.0; t11-18:1, 2.6 v. 1.7) despite greater total PUFA intakes for CBD. Milk RA concentration was greater for BBD than for CBD (1.46 v. 0.89) but was not influenced by the method of grain processing. This study clearly demonstrated that the milk content and profile of t-18:1 and CLA isomers were more strongly influenced by the source of grain starch (barley > corn) than by the method of grain processing indicating that factors inherent in the source of starch were responsible for the observed differences and these factors could not be modified by the processing methods used in this study.

Grazing cows are more efficient than zero-grazed and grass silage-fed cows in milk rumenic acid production.

Six rumen-cannulated Holstein cows in early lactation were assigned to 3 treatments: grazing (G), zero-grazing (ZG), and grass silage (GS) harvested from the same perennial rye grass sward in a 3 x 3 Latin square design with three 21-d periods. The objectives of this study were to investigate the underlying mechanisms for the reported elevation in milk rumenic acid (RA) concentration associated with G compared with ZG and GS, and to identify the important variables contributing to the milk RA response. Grazing animals were offered 20 kg of dry matter/cow per day; indoor animals were offered ad libitum grass or silage. A concentrate at a rate of 3 kg/d was also offered to all cows. Rumen, plasma, and milk samples were collected in the third week of each period. Data were analyzed by the MIXED procedure of SAS. Dry matter intakes were less for GS with no difference between G and ZG. Milk yield was greater for G than for ZG or GS. Milk fat and protein contents were less for GS with no difference between G and ZG. The combined intake (g/d) of linoleic and linolenic (18:3n-3) acids was different across the treatments (G: 433; ZG: 327; and GS: 164). Rumen pH was less for G with no difference between ZG and GS. Concentrations of volatile fatty acids and ammonia nitrogen in rumens were not different across the treatments. Wet rumen fill was less for G with no difference between ZG and GS. Vaccenic acid concentrations were different across the treatments in rumen (G: 12.30%, ZG: 9.31%, and GS: 4.21%); plasma (G: 2.18%, ZG: 1.47%, and GS: 0.66%) and milk (G: 4.73%, ZG: 3.49%, and GS: 0.99%). Milk RA concentrations were greater for G (2.07%) than for ZG (1.38%) and GS (0.54%). Milk desaturase index based on the ratio cis-9-14:1/14:0 was not different across the treatments. Milk RA yield per 100 g of linoleic acid and linolenic acid intake (efficiency) was 2.23, 1.50, and 0.62 g in G, ZG, and GS, respectively, suggesting that G cows were more efficient than ZG and GS cows in milk RA production. Stepwise regression analysis of a group of variables revealed that plasma vaccenic acid accounted for 95% of the variation in milk RA production. Milk desaturase index did not enter into the model. Overall findings suggest that substrate intake influenced milk RA production but it was not the only factor involved. There were differences in efficiency of milk RA production, which appears to depend on the factors regulating ruminal vaccenic acid production and its supply to the mammary tissue.

Nonionophore antibiotics do not affect the trans-18:1 and conjugated linoleic acid composition in beef adipose tissue.

The common practice in North American feedlot industries is to add antibiotics to the diet to prevent disease and improve both BW gain and feed efficiency. In this study, 240 crossbred steer calves were backgrounded on a 54% silage diet for 80 d and fed a finishing diet consisting of 81% barley grain, 10% barley silage, and 7.5% supplement (DM basis) with and without in-feed antibiotics for approximately 120 d. Calves were assigned to 1 of 5 treatments: a control with no antibiotics, 11 mg/kg of chlortetracycline, 44 mg/kg of chlortetracycline, 44 mg/kg of chlortetracycline plus 44 mg/kg of sulfamethazine, and 11 mg/ kg of tylosin phosphate. A combination of GLC and silver-ion HPLC methods was used to analyze the fatty acid composition of brisket adipose tissue, with emphasis on trans-18:1 and CLA isomers. The inclusion of nonionophore antibiotics in the diet had little effect on the fatty acid composition, except that feeding either 44 mg/kg of chlortetracycline or 11 mg/kg of tylosin caused small increases in 9c-14:1 and 16:0 relative to the control (0.26 and 0.9 g/100 g of total fatty acids, respectively). Likewise, profiles of trans-18:1 and CLA isomers were unchanged by antibiotics, but across treatments the predominant trans-18:1 isomer was 10t-18:1 (where t = trans; 3.22%) at 3 times the concentration of the second most abundant isomer (11t-18:1; vaccenic acid, 1.05%). Rumenic acid (9c,11t-18:2, where c = cis) was the major CLA isomer at 61% of total CLA, followed by 7t,9c-18:2 at 9%. Because no other effects on fatty acid composition were evident, data for trans-18:1 and CLA were pooled across treatments to investigate possible relationships among rumen PUFA metabolites. The total trans-18:1 content in brisket adipose tissue was positively correlated with 10t-18:1, but not with 11t-18:1, whereas the total CLA was positively correlated with 9c,11t-18:2, but not with 7t,9c-18:2. The 7t,9c-18:2 was, however, positively correlated with 10t-18:1 and 6t/7t/8t-18:1 but was negatively correlated with rumenic acid. These metabolic interrelationships suggest the presence of bacterial populations with distinct pathways for PUFA biohydrogenation in which either 10t-18:1 or 11t-18:1 predominate. Overall, the nonionophore antibiotics tested did not appreciably change adipose tissue composition and consequently could not be used to improve the trans-18:1 or CLA profile (i.e., increase vaccenic and rumenic acids at the expense of 10t-18:1).

Supplemental algal meal alters the ruminal trans-18:1 fatty acid and conjugated linoleic acid composition in cattle.

The effects of dietary algal supplementation, a source of docosahexaenoic acid, on the fatty acid profile of rumen lipids in cattle were evaluated, with special emphasis on CLA and trans fatty acids produced by rumen microbes. A diet based on corn silage was fed with supplements containing the following: 1) no algal meal and fed at 2.1 kg of DM/d (control), 2) algal meal and fed at 1.1 kg of DM/d (low algal meal), 3) algal meal and fed at 2.1 kg of DM/d (medium algal meal), and 4) algal meal and fed at 4.2 kg of DM/d (high algal meal). A modified lipid extraction procedure was developed to analyze the lipid changes in rumen fluid. The percentage of stearic acid (18:0) in rumen fluid was decreased by algal meal supplementation (P < 0.001) compared with control and was linearly dependent on the level of algal meal supplementation (P = 0.005). Total trans-18:1 in rumen fluid of cattle fed the control diet was 19% of total fatty acids. Addition of algal meal increased (P < 0.001) total trans-18:1 up to 43%, mostly due to 18:1 trans-10 that increased (P = 0.002) to 29.5% of total rumen fatty acids. This increase in 18:1 trans-10 seems to suggest a change in the rumen microbial population. Vaccenic acid (18:1 trans-11) increased quadratically (P = 0.005) with increasing level of algal meal supplementation in the diets. The total CLA content was low in the control (<0.9%) and increased with dietary algal meal addition, although not significantly; the greatest level was 1.5% with the medium algal meal diet. The increase of rumenic acid (cis-9, trans-11 CLA) was quadratic (P = 0.05) with algal meal supplementation, whereas trans-10, cis-12 CLA increased linearly with increased level of algal meal from 0.08 to 0.13% (P = 0.03). The ratio of trans-11 (cis-9, trans-11 CLA + 18:1 trans-11) to trans-10 (trans-10, cis-12 CLA + 18:1 trans-10) decreased from 2.45 to 0.77, 0.87, and 0.21 for the control, low algal meal, medium algal meal, and high algal meal diets, respectively. The content of docosahexaenoic acid in rumen fluid increased (P = 0.002) from 0.3 to 1.4% of total fatty acids with increasing level of algal meal supplementation in the diets. Our results suggest that algal meal inhibits the reduction of trans-18:1 to 18:0, giving rise to the high trans-18:1 content. In conclusion, algal meal could be used to increase the concentration in rumen contents of trans-18:1 isomers that serve as precursors for CLA biosynthesis in the tissues of ruminants.

Fourier transform near infrared spectroscopy: a newly developed, non-invasive method to measure body fat : non-invasive body fat content measurement using FT-NIR.

An FT-NIR technique is reported to provide a fast, accurate and low cost method of determining in-vivo human body fat content. The body fat content of 353 healthy subjects (154 males and 199 females) of various height, weight, and age were measured by FT-NIR and compared to 420 subjects investigated by magnetic resonance imaging (MRI). The procedure involved scanning each subject's upper ear that provided a necessary reflectance surface and proved representative of the subject's subcutaneous fat content. The average FT-NIR spectrum was compared to a reference mixture with known and similar fat content and composition to that of humans. The FT-NIR response was incorporated into an empirical equation using the ratio of subcutaneous to total body fat from MRI data, taking into account the subject's gender, height, weight and age. The results on the two data sets were similar and demonstrated that the FT-NIR technique can be used to obtain a measure of the body fat content of individuals, similar to that using MRI. In addition, the FT-NIR was used to more accurately monitor the fat content of sleep apnea patients.

Evaluating the conjugated linoleic acid and trans 18:1 isomers in milk fat of dairy cows fed increasing amounts of sunflower oil and a constant level of fish oil.

The objective was to evaluate different levels of sun-flower oil (SFO) in dairy rations to increase vaccenic (trans-11-18:1) and rumenic acids (cis-9,trans-11-18:2) in milk fat, and assess the content and composition of other trans-octadecenoic (trans-18:1) and conjugated linoleic acids (CLA) isomers. Eighty lactating Holstein cows were fed control diets for 4 wk and then placed on 4 diets for 38 d; milk fat was analyzed after 10 and 38 d. The treatments were: control, 1.5% SFO plus 0.5% fish oil (FO), 3% SFO plus 0.5% FO, and 4.5% SFO plus 0.5% FO. The forage-to-concentrate ratio was 50:50 and consisted of barley/alfalfa/hay silage and corn/barley grain concentrate. There were no differences in milk production. Supplementation of SFO/FO reduced milk fat compared with respective pretreatment periods, but milk protein and lactose levels were not affected. There was a linear decrease in all short- and medium-chain saturated fatty acids (SFA) in milk fat after 10 d (25.5, 24.1, 20.2, and 16.7%) and a corresponding linear increase in total trans-18:1 (5.2, 9.1, 14.1, and 21.3%) and total CLA (0.7, 1.9, 2.4, and 3.9%). The other FA in milk fat were not affected. Separation of trans-18:1 isomers was achieved by combination of gas chromatography (GC; 100-m highly polar capillary column) and prior separation of trans FA by silver ion-thin layer chromatography followed by GC. The CLA isomers were resolved by a combination of GC and silver ion-HPLC. The trans-11- and trans-10-18:1 isomers accounted for approximately 50% of the total trans-18:1 increase when SFO/FO diets were fed. On continued feeding to 38 d, trans-11-18:1 increased with 1.5% SFO/FO, stayed the same with 3%, and declined with 4.5% SFO/FO. Rumenic acid showed a similar pattern on continued feeding as trans-11-18:2; levels increased to 0.43, 1.5, 1.9, and 3.4% at 10 d and to 0.42, 2.15, 2.09, and 2.78% at 38 d. Rumenic acid was the major CLA isomer in all 4 diets: 66, 77, 78 and 85%. The CLA isomers trans-7,cis-9-, trans-9,cis-11-, trans-10,cis-12-, trans-11,trans-13-, and trans-9,trans-11-/trans-10,trans-12-18:2 also increased from 0.18 (control) to 0.52% (4.5% SFO/FO). Milk fat produced from 3% SFO/FO appeared most promising: trans-11-18:1 and cis-9,trans-11-18:2 increased 4.5-fold, total SFA reduced 18%, and moderate levels of trans-10-18:1 (3.2%), other trans-18:1 (6.6%) and CLA isomers (0.5%) were observed, and that composition remained unchanged to 38 d. The 4.5% SFO/FO diet produced higher levels of trans-11-18:1 and cis-9,trans-11-18:2, a 28% reduction in SFA, and similar levels of other trans-18:1 (9.2%) and CLA isomers (0.52%), but the higher levels of trans-11-18:1 and cis-9,trans-11-18:2 were not sustained. A stable milk fat quality was achieved by feeding moderate amounts of SFO (3% of DM) in the presence of 0.5% FO that had 4% vaccenic and 2% rumenic acids.

Determination of total trans fats and oils by infrared spectroscopy for regulatory compliance.

The mandatory requirement in many countries to declare the amount of trans fat present in food products and dietary supplements has led to a need for sensitive and accurate methodologies for the rapid quantitation of total trans fats and oils. Capillary gas chromatography (GC) and infrared spectroscopy (IR) are the two methods most commonly used to identify and quantify trans fatty acids for food labeling purposes (see the article by Delmonte and Rader in this ABC issue for a detailed presentation of GC methodology). The present article provides a comprehensive review of the IR technique and the current attenuated total reflection (ATR) Fourier-transform (FT) IR methodologies for the rapid determination of total trans fats and oils. This review also addresses potential sources of interferences and inaccuracies in FTIR determinations, particularly those done at low trans levels. Recent observations have shown that the presence of saturated fats caused interferences in the FTIR spectra observed for trans triacylglycerols. The recognition and resolution of previously unresolved quantitative issues improved the accuracy and sensitivity of the FTIR methodology. Once validated, it is anticipated that the new negative second-derivative ATR-FTIR procedure will make IR spectroscopy more suitable than ever, and a rapid alternative and/or complementary method to GC, for the rapid determination of total trans fats for regulatory compliance. Figure Infrared light bouncing inside an internal reflection crystal.

Short communication: Effects of a monensin premix on milk fatty acid content during subacute ruminal acidosis in dairy cows.

The effects of a monensin premix on milk fatty acid content during grain-induced subacute ruminal acidosis (SARA) in Holstein cows receiving a total mixed ration was investigated. Six multiparous, rumen-fistulated Holstein cows were used in a two-treatment, two-period crossover design with 6-wk periods. Experimental treatments were either a monensin premix or a placebo premix. At the beginning of wk 4, SARA was induced in experimental cows for a 10-d period using a grain challenge model. The administration of a monensin premix elevated milk fat proportion of total short-chain saturated fatty acids (sum of C4 to C15). Milk fat proportions of conjugated linoleic acid isomers were unaffected. Linolenic acid (C18:3n3) proportion in milk fat of monensin-treated cows were lower when compared with placebo-treated cows during the SARA period. Results from this study indicate that dietary supplementation with monensin during SARA had little effect on milk fatty acid content.

Effects of fasting on muscle mitochondrial energetics and fatty acid metabolism in Ucp3(-/-) and wild-type mice.

Uncoupling protein-3 (UCP3) is a mitochondrial carrier protein of as yet undefined physiological function. To elucidate characteristics of its function, we studied the effects of fasting on resting metabolic rate, respiratory quotient, muscle Ucp3 expression, and mitochondrial proton leak in wild-type and Ucp3(-/-) mice. Also analyzed were the fatty acid compositions of skeletal muscle mitochondria in fed and fasted Ucp3(-/-) and wild-type mice. In wild-type mice, fasting caused significant increases in Ucp3 (4-fold) and Ucp2 (2-fold) mRNA but did not significantly affect mitochondrial proton leak. State 4 oxygen consumption was not affected by fasting in either of the two groups. However, protonmotive force was consistently higher in mitochondria of Ucp3(-/-) animals (P = 0.03), and fasting further augmented protonmotive force in Ucp3(-/-) mice; there was no effect in wild-type mitochondria. Resting metabolic rates decreased with fasting in both groups. Ucp3(-/-) mice had higher respiratory quotients than wild-type mice in fed resting states, indicating impaired fatty acid oxidation. Altogether, results show that the fasting-induced increases in Ucp2 and Ucp3 do not correlate with increased mitochondrial proton leak but support a role for UCP3 in fatty acid metabolism.