Mapping between prosodic hierarchy and supralaryngeal articulatory variations in French

International audienceThe gradual behaviour of articulatory supralaryangeal variations as a function as an 8-level vs a 4-level prosodic hierarchy was analysed here. Comparisons between the results related to each hierarchy suggested that 4-level hierarchy was sufficient to account for prosodic-dependent articulatory changes in French. These results allowed to discuss the architecture of hierarchical prosodic representation of speech.Le comportement graduel de variations articulatoires suprasegmentales en fonction d'une hiérarchie prosodique de 8 vs 4 niveaux est analysé ici. Les comparaisons des résultats entre ces 2 hiérarchies suggèrent qu'une hiérarchie à 4 niveaux est suffisante pour rendre compte des changements articulatoires impliqués par la structure prosodique en français. Ces résultats permettent de discuter de l'architecture des représentations prosodiques hiérarchiques de la parole

Enzymatic approach of linoleic acid ruminal biohydrogenation

Ruminal biohydrogenation (BH) corresponds to a microbial reduction of dietary unsaturated fatty acid. The linoleic acid (C18:2) BH is divided into three steps: first an isomerisation into conjugated linoleic acids (CLA), then a reduction producing mainly trans-octadecenoic acids (trans-C18:1), and a final reduction producing stearic acid (C18:0). Isomerisations of CLA and trans-C18:1 can lead to a number of positional and geometrical isomers. The control of BH reactions is of interest for researchers because BH directly affects the composition of fatty acids of milk and meat. In order to better understand C18:2 BH and its variations, the development of an enzymatic approach is necessary to ascertain if the action of modulators affects the bacterial enzyme activity or ruminal bacteria. The aim of this study was to investigate the C18:2 BH capacity of ruminal content after inactivation of bacteria by chloramphenicol (Cm), an inhibitor of protein synthesis in prokaryotes. The BH of C18:2 produced mainly cis9,trans11-CLA and trans10,cis12-CLA, and trans11-C18:1 and trans10-C18:1 isomers, as previously described (Jouany et al., 2007). The increase in cis12-C18:1 came from reduction of trans10,cis12-CLA, that of trans6+7+8-C18:1 from the reduction of minor CLA isomers not quantified in this study, like trans8,trans10-CLA (Shingfield et al., 2008). The trans11 pathway was rapid: the cis9,trans11-CLA production was maximal at about 1h of incubation while trans11-C18:1 accumulated throughout incubation. On the other hand, trans10 pathway was slow: trans10,cis12-CLA regularly increased during incubation, so that it was more abundant than cis9,trans11-CLA after 3h incubation, and trans10-C18:1 only began to increase after 2h of incubation. The amount of C18:0 began to increase in the media when trans11-C18:1 concentration was over 0.05 mg/mL. Such evolution of fatty acids involved in C18:2 BH was similar to that reported in vitro with living ruminal microorganisms by Harfoot et al. (1973) and Jouany et al. (2007). So, this enzymatic approach using Cm could be an interesting and valid method to study C18:2 BH, however 3h of incubation were not sufficient to study the final reduction

Effects of fat source and dietary sodium bicarbonate plus straw on the conjugated linoleic acid content of milk of dairy cows

The effects of fat source (0.7 kg of fatty acids from extruded soybeans or palmitic acid), of sodium bicarbonate (0.3 kg) plus straw (1 kg) and the interaction of these treatments on the content of conjugated linoleic acid (CLA) in the milk of dairy cows were examined. During nine weeks a group of 10 cows received a ration with palmitic acid and bicarbonate plus straw (ration PAB). During three periods of three weeks a second group of 10 cows received successively a ration with extruded soybeans and bicarbonate plus straw (ration ESB), a ration with palmitic acid without bicarbonate or straw (ration PA), and a ration with extruded soybeans without bicarbonate or straw (ration ES). Rations ES and ESB increased the content of polyunsaturated fatty acids in milk, but decreased milk fat content, compared to rations PAB and PA. Ration ESB led to the greatest milk CLA content, by a synergy between the high amount of dietary fat, and the action of bicarbonate plus straw, favouring trans11 isomers of CLA and C18:1, presumably via a ruminal pH near neutrality. Ration ES favoured trans10 isomers, not desaturated in the mammary gland, so that the milk CLA content was lower than with ration ESB, and resulted in the lowest milk fat content. In conclusion, a ration supplemented with both extruded soybeans and bicarbonate plus straw, was an efficient way to increase the CLA content in the milk of dairy cows

Polymers of triglycerides generated during heating of fat do not protect linoleic acid from ruminal biohydrogenation

Heating fats often induces a decrease of cis-9, cis-12 C18:2 and cis-9, cis-12, cis-15 C18:3 biohydrogenation (BH) in vivo (Gonthier et al. 2005), in situ (Troegeler-Meynadier et al. 2006) and in vitro (Privé et al. 2010). This is of interest because it could increase polyunsaturated fatty acids (PUFA) content of ruminant products. Temperature and duration of heating of sunflower oil affect ruminal BH of PUFA, in part due to peroxide value (Privé et al., 2010). Our hypothesis was that polymers of triglycerides (TG), formed during heating of TG but not of free FA, could be responsible for partial protection of PUFA from BH

The ruminal ratio of trans-10/trans-11 fatty acids obtained in vitro reflects in vivo values and strongly depends on the diet of the donor cow

Composition of fatty acids (FA) of ruminant products has a potential impact on human health. Among them, trans FA, which are intermediates of the ruminal biohydrogenation of dietary unsaturated FA, deserve interest, in particular trans-10 and trans-11 isomers, which would have negative and positive effects on human health, respectively (Tricon et al., 2004). A large variability in the ratio of trans-10 to trans-11 isomers (t10/t11) has been observed (Shingfield et al., 2006). Some dietary factors shifting from t11 to t10 have been identified, like the proportion of concentrate (Griinari et al., 1998), or the addition of oil (Roy et al., 2006). The use of in vitro systems to simulate rumen fermentation presents technical, economical and ethical advantages compared to in vivo experiments, and allows screening studies. The aim of the present study was to investigate if the ruminal fluid of a cow having the t11 to t10 deviation results in the same deviation during in vitro batch incubation and if the pathway of biohydrogenation in vitro depends mainly on the donor cow or on the fermentative substrate. This study showed that the t10/t11 ratio of the ruminal fluid after 5 hours in vitro incubation reflects the in vivo values. This ratio in vitro did not depend on cultures substrates, but related to the diet of the donor cows, suggesting a major importance of the ruminal inoculum on the biohydrogenation pathway. This might be due to the short incubation time preventing the bacterial communities to evolve according to the in vitro substrate. As a consequence, short duration batch in vitro cultures cannot be used to study the dietary conditions of the t11 to t10 shift. Nevertheless, they could possibly be used for the study of the effects of feed additives on the t10/t11 ratio

In vitro study of dietary factors affecting the biohydrogenation shift from trans-11 to trans-10 fatty acids in the rumen of dairy cows

On the basis of the isomer-specific effects of trans fatty acids (FA) on human health, and the detrimental effect of t10,c12-conjugated linoleic acid (CLA) on cows’ milk fat production, there is a need to identify factors that affect the shift from trans-11 to trans-10 pathway during ruminal biohydrogenation of FA. This experiment was conducted in vitro and aimed at separating the effects of the diet of the donor cows from those of the fermentative substrate, which is necessary to prevent this shift. A total of four dry Holstein dairy cows were used in a 434 Latin square design. They received 12 kg of dry matter per day of four diets based on maize silage during four successive periods: the control diet (22% starch, ,3% fat); the high-starch diet, supplemented with wheat plus barley (35% starch, ,3% crude fat); the sunflower oil diet, supplemented with 5% of sunflower oil (20% starch, 7.6% crude fat); and the high-starch plus oil diet (33% starch, 7.3% crude fat). Ruminal fluid of each donor cow was incubated for 5 h with four substrates having similar chemical composition to the diets, replacing sunflower oil by pure linoleic acid (LA). The efficiency of isomerisation of LA to CLA was the highest when rumen fluids from cows receiving dietary oil were incubated with added LA. The shift from trans-11 to trans-10 isomers was induced in vitro by high-starch diets and the addition of LA. Oil supplementation to the diet of the donor cows increased this shift. Conversely, the trans-10 isomer balance was always low when no LA was added to incubation cultures. These results showed that a large accumulation of trans-10 FA was only observed with an adapted microflora, as well as an addition of non-esterified LA to the incubation substrate

Starch plus sunflower oil addition to the diet of dry dairy cows results in a trans-11 to trans-10 shift of biohydrogenation

Trans fatty acids (FA), exhibit different biological properties. Among them, cis-9,trans-11 conjugated linoleic acid has some interesting putative health properties, whereas trans-10,cis-12 conjugated linoleic acid has negative effects on cow milk fat production and would negatively affect human health. In high-yielding dairy cows, a shift from trans-11 to trans-10 pathway of biohydrogenation (BH) can occur in the rumen of cows receiving high-concentrate diets, especially when the diet is supplemented with unsaturated fat sources. To study this shift, 4 rumen-fistulated nonlactating Holstein cows were assigned to a 4 × 4 Latin square design with 4 different diets during 4 periods. Cows received 12 kg of dry matter per day of 4 diets based on corn silage during 4 successive periods: a control diet (22% starch, <3% crude fat on DM basis), a high-starch diet supplemented with wheat plus barley (35% starch, <3% crude fat), a sunflower oil diet supplemented with 5% of sunflower oil (20% starch, 7.6% crude fat), and a high-starch plus sunflower oil diet (33% starch, 7.3% crude fat). Five hours after feeding, proportions of trans-11 BH isomers greatly increased in the rumen content with the addition of sunflower oil, without change in ruminal pH compared with the control diet. Addition of starch to the control diet had no effect on BH pathways but decreased ruminal pH. The addition of a large amount of starch in association with sunflower oil increased trans-10 FA at the expense of trans-11 FA in the rumen content, revealing a trans-11 to trans-10 shift. Interestingly, with this latter diet, ruminal pH did not change compared with a single addition of starch. This trans-11 to trans-10 shift occurred progressively, after a decrease in the proportion of trans-11 FA in the rumen, suggesting that this shift could result from a dysbiosis in the rumen in favor of trans-10-producing bacteria at the expense of those producing trans-11 or a modification of bacterial activities

Effects of induced acidosis on milk fat content and milk fatty acids profile

Objective: The effect of wheat percentage in diets offered to lactating cows on variations of milk fat content and profile of milk fatty acids (FA) was studied, focusing on odd-chain FA and trans intermediates of ruminal biohydrogenation. Materials and methods: Two cows equipped with a ruminal canula successively received diets based on maize silage, and comprising 0, 20, 34 and again 0% wheat on a dry matter basis. Each diet was used during 12 days. The diet was distributed in two equal meals at 08:00 and 17:00, and wheat was top-dressed on silage. Milk samples were taken at the evening milking, and samples of ruminal contents were taken hourly from 08:00 to 16:00 on days 10 and 11 in the first period, and on days 5, 10 and 11 in the 3 subsequent periods. Results and discussion: Compared with the initial control, after 10 days adaptation, diet with 20% wheat significantly lowered mean ruminal pH (6.03 vs 6.77) and milk fat content (33.0 vs 44.1), and significantly increased the percentage of odd-chain FA in milk fat (2.38 vs 1.48). The trans-10C18:1 / trans-11C18:1 ratio increased from 0.34 to 0.82, but the difference was not significant. After 10 days adaptation, the diet with 34% wheat resulted in low ruminal pH (5.8), low milk fat content (22.4), and high percentage of odd-chain FA (3.03) and high trans-10C18:1 / trans-11C18:1 ratio (12.2). All these values were significantly different from both initial values and values observed with 20% wheat. After 10 days with the control diet following acidogenic diets, mean ruminal pH and milk fat content returned near initial value (6.98 and 41.1, respectively), but odd-chain FA and the trans-10C18:1 / trans-11C18:1 ratio (1.80 and 2.14, respectively) remained significantly higher than initial values. This suggests that the effects of a ruminal acidosis can remain a long time after returning to a non-acidogenic diet. Values observed after 5 days adaptation to the three diets were intermediate between values at the end of the previous period and values after 10 days adaptation, and significantly different from values after 10 days adaptation for all presented parameters except the trans-10C18:1 / trans-11C18:1 ratio (P = 0.25). The correlation coefficients between mean ruminal pH and milk fat content, proportion of odd-chain FA and the trans-10C18:1 / trans-11C18:1 ratio were significant (0.84, ־0.87 and ־0.62, respectively). However, this low latter value was due to a weak relationship when pH was over 6.2, and a large increase of the trans-10C18:1 / trans-11C18:1 ratio when mean ruminal pH was under 6.2. These results are consistent with present knowledge on trans-10 FA as a result of low ruminal pH and a cause of low milk fat content. They show that the trans-10C18:1 / trans-11C18:1 ratio can exhibit very large variations when the mean ruminal pH is under 6.2. Conclusion and perspective: Induced acidosis resulted in lowered milk fat content, and higher proportion of odd-chain FA and a higher trans-10C18:1 / trans-11C18:1 ratio. Milk fat content and proportion of odd-chain FA were linearly related to mean ruminal pH. On the contrary, trans-10C18:1 / trans-11C18:1 ratio only exhibited variations when mean ruminal pH was low, and these variations were in a large range, making this ratio a possible candidate for biochemical characterisation of acidosis

Effect of cow diet on the ruminal microflora and its in vitro fatty acid production

The objective of this study was to investigate the effects of donor’s cow diet (hay or maize silage plus concentrates) on ruminal bacteria count, flora diversity and fatty acids profile (FA) of ruminal fluid and in vitro biohydrogenation (BH) of C18:2. Two dry cows fitted with a ruminal canula were used in a 2x2 design. Each period included three weeks of diet adaptation and two weeks of sampling. The cows were fed twice daily either a diet (H) composed of grass (38%) and alfalfa hay (62%) or an acidogenic diet (A) composed of maize silage (38%), wheat (57%) and soybean (5%) meal. Ruminal fluid was sampled and centrifugated (150g, 5min., 39°C). The ruminal fluid (80mL) was mixed with 80mL of buffer, a fermentative substrate and grape seed oil as source of C18:2 before being incubated during 6 hours at 39°C in anaerobic and dark conditions. Biodiversity was estimated by the Simpson index modified by Haegeman et al.1 after SSCP analysis, and FA were analysed by GLC. Bacteria counting was realised according to Oblinger and Koburger2 (1975). Total and cellulolytic bacteria contents were higher in inoculum A than in inoculum H (9.3.109 vs. 2.4.108/mL for total bacteria and 2.4.108 vs. 1.6.107/mL for cellulolytic bacteria). No difference in the biodiversity of the inoculums was noticed according to the cow or the diet, but diversity during period 1 tended to differ (P=0.09) from period 2, suggesting a time variation of flora biodiversity. Before incubation, the ruminal fluid from the cow receiving diet A contained significantly (P<0.01) more C18:2, trans-10 and trans-11 C18:1, and odd-chain FA than inoculum from the cow receiving diet H. After incubation, inoculum A resulted in a significantly (P<0.01) greater BH of C18:2 than inoculum H, and produced more trans-10C18:1, trans-11C18:1 and odd-chain FA (P<0.01) Trans-10 and odd-chain FA are known to be increased by a high concentrate diet, which explains that inoculum A was richer in these FA than inoculum H. The ruminal flora selected in vivo by diet A continued the production of these FA in vitro. The greater content of trans-11C18:1 and of C18:2 in the inoculum A could be explained by the greater content in C18:2 of the diet A. During incubation with added C18:2, inoculum A continued to produce more trans-11 along with a higher C18:2 BH than inoculum H, which could be due to the higher concentration of cellulolytic bacteria in the inoculum A

Contraste de voisement en parole chuchotée

International audienceVoicing contrast in whispered speech This paper presents analyses on the phonological voicing contrast in whispered speech, which is characterized by a semi-open configuration of the vocal folds preventing them from vibrating. In modal speech, in addition to vocal fold vibration, the contrast between voiced and unvoiced consonants is realized by other phonetic correlates: e.g. consonant and pre-consonantal vowel durations, intraoral pressure differences. Acoustic and aerodynamic analyzes show that these voicing correlates are preserved in whispered speech. These findings seem consistent with those showing that voiced contrast is maintained in perception despite the absence of vocal fold vibration.Ce travail porte sur le contraste phonologique de voisement en parole chuchotée qui se caractérise par une configuration semi-ouverte des cordes vocales empêchant leur vibration. En parole modale, outre la vibration des cordes vocales, le contraste entre consonnes voisées et sourdes est supporté par d'autres corrélats phonétiques : durées des consonnes et des voyelles, pression intraorale, entre autres. Les analyses acoustiques et aérodynamiques des consonnes voisées vs sourdes montrent que ces corrélats secondaires du voisement sont préservés en parole chuchotée, pouvant donner une assise à la persistance de la perception de ce contraste malgré l'absence de vibration des cordes