Dairy goats adjust their meal patterns to the fibre content of the diet.

Few studies have investigated how meal patterns of ruminants are affected by diet fibre content. Dairy goats (N = 32) in late lactation and early gestation were housed in eight groups of four goats, with all combinations of breed (Alpine and Saanen) and lactation number (1 and 2) represented in each group. Each goat had access to its own individual feed trough placed on a weigh scale with data logged automatically. All goats were fed the same total mixed ration (TMR; 30% concentrate and 44.6% NDF in DM) ad libitum for a control period of 22 days. Using the same feed ingredients, half of the groups were then offered a High fibre diet (20% concentrate; 47.3% NDF), and the other half a Low fibre diet (40% concentrate; 41.5% NDF) for a treatment period of 16 days. Daily meal patterns (meal frequency, duration and size, feeding rate, daily feed intake and daily feeding time) were computed for each animal using a meal criterion of 8 min. The last 10 days for each period (control and treatment) were used to calculate individual period means and individual differences between the two periods. During the control period, the goats ate on average 12.1 ± 0.49 meals/day, consuming 4.2 ± 0.10 kg fresh TMR daily. When the ration changed, all measures of feeding behaviour except meal size changed asymmetrically for the goats on the two diets. Goats fed the High fibre diet reduced their meal frequency by 10%, and the first meal after feed distribution lasted 11% longer, leading to a 9% reduction in feeding rate and no significant changes in daily feed intake and daily feeding time. Goats on the Low fibre diet did not significantly change their meal frequency or meal size, but the combined changes nevertheless led to a 9% increase in daily feed intake. On the Low fibre diet, goats were able to increase their feeding rate by a third, leading to a reduction in meal durations, thus reducing daily feeding time by 13%. Goats adapt their feeding behaviour to the fibre proportion of the offered diet, with more changes when fibre content is lowered, which needs to be taken into account when comparing phenotypes and adaptability of small ruminants to different diets.

Repeatability of traits for characterizing feed intake patterns in dairy goats: a basis for phenotyping in the precision farming context.

In ruminants, feeding behaviour variables are parameters involved in feed efficiency that show variation among individuals. This study aimed to evaluate during the first two production cycles in ruminants the repeatability of feed intake pattern, which is an important aspect of feeding behaviour. Thirty-five dairy goats from Alpine or Saanen breeds were housed in individual pens at four periods (end of first gestation, middle of first and second lactations and middle of second gestation which is also the end of first lactation) and fed a total mixed ration (TMR) ad libitum. Individual cumulative dry matter intake (DMI) was automatically measured every 2 min during the last 4 days of each period. Feed intake pattern was characterized by several measures related to the quantity of feed eaten or to the rate of intake during the 15 h following the afternoon feed delivery. Two main methods were used: modelling cumulative DMI evolution by an exponential model or by a segmentation-clustering method. The goat ability to sort against dietary fibre was also evaluated. There was a very good repeatability of the aggregate measures between days within a period for a given goat estimated by the day effect within breed and goat, tested on the residual variance (P > 0.95). The correlations between periods were the highest between the second and either the third or fourth periods. With increasing age, goats sorted more against the fibrous part of the TMR and increased their initial rate of intake. Alpine goats ate more slowly than Saanen goats but ate during a longer duration. Principal component analysis (PCA) was performed on all the aggregate measures of feed intake patterns. The factor score plots generated by the PCA highlighted the opposition between the different measures of feed intake patterns and the sorting behaviour. The projection of the animals on the scoring plots showed a breed effect and that there was a continuum for the feed intake pattern of goats. In conclusion, this study showed that the feed intake pattern was highly repeatable for an animal in a given period and between periods. This means that phenotyping goats in a younger age might be of interest, either to select them on feeding behaviour and choose preferentially the slow eaters or to adapt the quantity offered and restrict feed delivery to the fast eaters in order to increase feed efficiency and welfare by limiting the occurrence of acidosis, for example.

Effect of concentrate level on feeding behavior and rumen and blood parameters in dairy goats: relationships between behavioral and physiological parameters and effect of between-animal variability.

This work aimed first to compare 2 diets differing in their percentage of concentrate [low (LO): 30% concentrate vs. High (HI): 60% concentrate] by measuring simultaneously feeding behavior, rumen parameters, blood and plasma parameters, and milk yield and composition in 8 mid-lactation goats. The second aim was to study the interrelationships between these variables and to analyze the between-animal variability to better understand the between-animal differences in acidosis susceptibility. All of the animals received the 2 diets ad libitum as total mixed ration according to a crossover design of two 4-wk periods. Mean daily DMI was similar between the 2 diets but the variability was higher for the HI than for the LO diet. Goats produced more milk when fed the HI diet compared with the LO diet but with a lower fat:protein ratio (0.81 vs. 0.99). They ate more rapidly the HI than the LO diet but stopped eating sooner after the afternoon feed allowance, and spent less time chewing. The increase in concentrate percentage modified rumen parameters: the pH and acetate:propionate ratio decreased and total VFA, ammonia, and soluble carbohydrate concentrations increased. Hematocrit, plasma NEFA, and blood K and Ca concentrations decreased but glycemia and uremia increased. Other parameters were not modified: milk fat content, blood pH, and bicarbonate and Na concentrations. A large between-animal variability was detected for all the measured parameters, especially for feeding behavior, with important consequences on rumen and blood parameters. This work confirmed the effects of a high percentage of concentrate on feeding behavior, rumen and blood parameters, and milk production, and some known relationships such as the positive link between rumen pH and chewing index. It also pointed out other relationships between parameters seldom measured at the same time, such as rumen redox potential or blood pH and chewing index, or the negative link between blood and rumen pH. When the animals spent a lot of time chewing, they probably produced a lot of saliva that buffered the rumen pH and prevented them from suffering from subacute ruminal acidosis. However, they used part of their blood bicarbonates reserve, which might have induced metabolic acidosis, as rumen and blood pH were inversely related. This could explain why some animals suffer from acidosis and others do not in a herd receiving the same diet, and why some animals seem to suffer more from subacute ruminal acidosis and others from metabolic acidosis.

[General recommendations for medical treatment after heart transplantation]. / Aspects médicaux autour de la transplantation cardiaque en 2014.

Heart transplantation remains the treatment of choice in selected patients with severe heart failure (HF) despite optimal medical therapy. Since long-term survival after HTX is improving, there is a growing need for evidence-based strategies that reduce long-term mortality resulting from both immunological and non-immunological risk. This manuscript summarizes recommendations for treatment of transplant vasculopathy, malignancy after transplantation, and prevention of corticosteroid induced bone disease. Based on actual understanding of cardiovascular risk factors in the population, preservation of renal function, prevention and treatment of hyperlipidemia and diabetes, as well as blood pressure control play an important role in the long-term follow-up after heart transplantation.

[Long-term mechanical circulatory support: where do we stand in 2013?]. / Assistance circulatoire chronique: le point en 2013.

With the advent of new technologies, experience with long-term mechanical circulatory support (MCS) is rapidly growing. Candidates to MCS are selected based on concepts, strategies and classifications that are specific to this indication. As results drastically improve, supported by stronger scientific evidence, the trend is towards earlier implantation. An adequate pre-implant follow-up is mandatory in order to avoid missing the best window of opportunity for implantation. While on chronic support, the hemodynamic profile of patients with continuous-flow ventricular assist devices is unique and remarkably influenced by the hydration status. Optimal management of these patients from the pre-implant phase to the long-term support phase requires a multidisciplinary approach that is similar to that already long validated for organ transplantation.

Effects of the percentage of concentrate on rumen fermentation, nutrient digestibility, plasma metabolites, and milk composition in mid-lactation goats.

The aim of this work was to study the effects of the dietary percentage of concentrate on patterns of intake, the evolution of rumen fermentation characteristics and plasma metabolites after a meal, nutrient digestibility, and milk production and composition in a medium-term trial in dairy goats. These effects have been well studied in dairy cattle but seldom in goats. Thirteen ruminally and duodenally cannulated dairy goats (95±4 d in milk) fed ad libitum were used in this study. Goats were assigned to 1 of 2 dietary treatments: high-concentrate (70% concentrate on dry matter basis) or a low-concentrate (35%) total mixed rations. The experiment was conducted over a period of 10 wk, including 3 wk of adaption to the diets. Patterns of intake, rumen fermentation characteristics, and plasma metabolites after a meal and fatty acids profile of milk fat were compared at the onset and at the end of the experiment. The increase in dietary percentage of concentrate decreased rumen pH, acetate to propionate ratio, ammonia-N concentration, and plasma urea concentration. The percentage of concentrate did not affect total volatile fatty acid concentrations. The high-concentrate diet increased the rate of intake during the morning meal at the onset of the experiment, whereas it decreased total dry matter intake and the rate of intake during the morning meal at the end of the experiment. The high-concentrate diet resulted in greater organic matter digestibility. Raw milk yield and protein yield were greater in goats fed the high-concentrate diet, whereas fat yield was not affected by dietary treatments. The milk fat content was lower in goats fed the high-concentrate diet. Proportions of the trans-C18:1 isomer relative to total fatty acids in milk were higher with the high-concentrate diet, but no modification of the proportion of total trans-C18:1 was detected, in particular no shift from trans-11 C18:1 to trans-10 C18:1 was observed. Further, the isomer trans-10,cis-12 C18:2 was not detected. Data from this study could be used for a new modeling approach or to improve existing models.

The use of a multivariate analysis to study between-goat variability in feeding behavior and associated rumen pH patterns.

This study examined feeding patterns and their relation to rumen pH. The measured variables were the cumulative time spent chewing (eating or ruminating) and the mean rumen pH, per 20-min intervals (46 intervals altogether). A total of 333 feeding patterns, defined as time-series of measurements for 1 animal and 1 given day during 15 h and 20 min following the afternoon feeding, were collected from 12 stall-housed dairy goats fed a total mixed ration twice daily. The first objective of this study was to analyze the within-day variability of feeding behavior to characterize different feeding patterns. The second objective was to analyze, for each goat, the between-day variability of its feeding behavior. The third objective was to study the influence of feeding behavior on rumen pH. A multivariate method (principal component analysis) was performed on the time spent eating or ruminating during each of the 46 intervals. The factor score plots generated by the principal component analysis highlighted the evolution in time of chewing activities. They also were used to determine 4 different types of feeding behavior in the extreme patterns of the first 2 axes. These feeding patterns were associated with different rumen pH patterns in goats with the same total dry matter intake and mean rumen pH. Some goats had a major eating period immediately after feeding, followed by a period of rumination; this pattern was associated with a marked decrease in rumen pH and a pH nadir below 6.0. Other goats performed alternate periods of eating and ruminating throughout the studied period. The latter feeding pattern was associated with a shorter total duration of rumination, but a more stable rumen pH than the feeding pattern described previously. Feeding pattern was quite constant between days for some goats, but highly variable for others. However, the continuum observed between these 4 groups shows that many intermediate types of behavior can be observed. In conclusion, characterizing animals according to their feeding behavior by using a principal component analysis may provide information on the animal's predisposition to rumen acidosis.

[When the heart and/or the lung fails: the ECMO]. / Quand le coeur et/ou les poumons défaillent: oxygénation extracorporelle par "ECMO".

The Extra corporeal membrane oxygenation (ECMO) was initially proposed as a technique of respiratory support using an external membrane oxygenator. With time, it has also become a technique of cardiorespiratory support to ensure both gas exchange and organ perfusion until the restoration of organs function. This technical assistance can be central or peripheral and provides a partial or total circulatory support. The circuit includes a non occlusive centrifugal pump, an oxygenator for an enrichment of O2 and elimination of CO2 and cannulas for drainage and re-injection. Recently, the establishment of such assistance became possible percutaneously, allowing it to be initiated at the intensive care bedside or even before in-hospital admission.

Modeling of off-feed periods caused by subacute acidosis in intensive lactating ruminants: application to goats.

Off-feed periods caused by subacute rumen acidosis are often observed in intensive ruminant production systems but appear in an unpredictable manner. The objectives of this paper were first, to study the influence of spontaneous off-feed periods due to bouts of acidosis on milk composition and on some rumen and blood parameters and second, to model the day-to-day variations in rumen pH, dry matter intake (DMI), and milk production during these bouts of acidosis. Twenty-five spontaneous off-feed periods were detected in an experiment performed in 18 mid-lactating goats fed a high concentrate diet over 11 wk. Dry matter intake, milk production, and rumen pH were measured daily during the experiment, which allowed us to model the day-to-day evolution of these 3 parameters during spontaneous bouts of acidosis. Bouts started with a very rapid pH decrease (1 d) followed by several days of relatively high rumen pH (>6.5) before recovery of preacidosis values. The pH decrease was followed by a decrease in DMI, reaching a nadir around 2 d after the start of the episode, and a milk yield decrease, reaching a nadir 3 d after the beginning of the episode. The high rumen pH was caused by the relatively small decrease in daily chewing time during the decrease in DMI. Therefore, chewing time per unit of DMI increased, which probably increased the buffer supply per unit of DMI. Dry matter intake and milk yield needed around 20 d to recover to preacidosis values. Energy balance also decreased during DMI and milk yield decreases but recovered more rapidly than DMI and milk yield. However, energy balance cumulated from the start of the bout of acidosis remained negative for more than 10 d. Milk composition and rumen and blood parameters were not measured daily and therefore could not be used in the modeling process. However, during off-feed periods, milk fat and protein contents were negatively correlated with DMI, whereas milk lactose content was positively correlated with DMI. Low DMI was also linked to low blood pH, bicarbonates, and low rumen volatile fatty acids but high levels of plasma nonesterified fatty acids. This indicates that rumen fermentation was reduced and body reserves were mobilized during bouts of acidosis. This analysis showed that spontaneous bouts of acidosis in intensively reared dairy ruminants can have a great influence on animal production and health over at least 3 wk, and can thus represent an important economic loss.

Meta-analysis of the influence of Saccharomyces cerevisiae supplementation on ruminal parameters and milk production of ruminants.

The effects of yeast supplementation on intake, production, and rumen fermentation characteristics have been widely studied, but results are inconsistent between different studies. A quantitative meta-analysis was applied to 110 papers, 157 experiments, and 376 treatments dealing with yeast supplementation in ruminants. The objective was first to highlight the major quantitative effects of live yeast supplementation on intake, rumen fermentation, and milk production, and second, to identify major differences in experimental conditions between studies that can affect the response to treatment. Some of these experimental conditions are referred to as interfering factors. Yeast supplementation increased rumen pH (+0.03 on average) and rumen volatile fatty acid concentration (+2.17 mM on average), tended to decrease rumen lactic acid concentration (-0.9 mM on average), and had no influence on acetate-to-propionate ratio. Total-tract organic matter digestibility was also increased by yeast supplementation (+0.8% on average). Yeast supplementation increased dry matter intake (DMI; +0.44 g/kg of body weight; BW), milk yield (+1.2 g/kg of BW), and tended to increase milk fat content (+0.05%), but had no influence on milk protein content. Dose effects of yeast supplementation, expressed as log(10) [1+(cfu per 100 kg of BW)], globally confirmed the qualitative effects observed in the first analysis. The positive effect of yeast supplementation on rumen pH increased with the percentage of concentrate in the diet and with the DMI level. It was negatively correlated with the level of dietary neutral detergent fiber (NDF). The positive effect of yeast supplementation on rumen volatile fatty acid concentration increased with DMI and crude protein levels. The positive effect of yeast supplementation on organic matter digestibility increased with the percentage of concentrate and NDF in the diet. The negative effect of yeast supplementation on lactic acid concentration tended to decrease when the DMI level and the percentage of concentrate in the diet increased. The effects of interfering factors were globally similar when either dose effect or qualitative effect of yeast was taken into account. Although rumen fermentation efficiency per se was not measured, these results suggest an improvement in rumen fermentation by yeast supplementation. This effect could, however, be modulated by several different factors such as DMI, percentage of concentrate or NDF in the diet, or species.

Meta-analysis of 0 to 8 h post-prandial evolution of ruminal pH.

The objective of this study was to identify relevant descriptors of ruminal pH post-prandial evolution that can replace the mean pH (considered unsatisfactory). These descriptors are to be used in the attempts to predict ruminal pH from dietary characteristics, in order to quantify the potential of a diet to induce subacute ruminal acidosis from its intrinsic characteristics. A total of 219 pH curves, reported as graphics in 48 published articles describing the post-prandial evolution of ruminal pH (first 8 h), were digitized by image analysis then summarized in 15 pH variables. Relationships among pH variables and the principal components (PCs) of pH variability were analyzed in order to identify possible alternatives to mean pH, as the average value of all pH data the curve is composed of. Two groups of pH variables were identified according to their relationship with the most important principal components. A first group, including mean pH, was closely related to PC1, which accounted for 78% of data variability; hence, correlations between variables of this group were generally high. Of these, threshold-related variables were distinct as their within-study correlations with mean pH were rather moderate (0.69 on average). This suggests they might carry supplementary information that could explain the variation in ruminal pH induced by within-study factors, e.g. diet characteristics. However, caution should be taken in their use because of their truncation at 0 h and their non-normal distribution. Variables from the second group were independent of the PC1, and thus of the first group of variables, whereas they were mostly related to PC2 and PC3. This implies they are complementary to mean pH. Of this second group, the rate of pH decreases or the time period when pH reaches its minimum might be useful to better describe the ruminal status, from the point of view of the risk of subacute ruminal acidosis.

Effect of concentrate percentage on ruminal pH and time-budget in dairy goats.

The aim of this study was to compare rumen pH and time-budget in eight mid-lactation goats receiving two diets in a cross-over design (low-concentrate diet (L): 30% and high-concentrate diet (H): 60% concentrate). Feeding H increased daily intake (4.3 ± 0.08% v. 4.7 ± 0.08% of body weight for L and H, respectively) and daily milk production (3.01 ± 0.130 v. 3.50 ± 0.130 kg/day of 3.5% fat-corrected milk for L and H, respectively). It decreased milk fat and inverted the fat-to-protein ratio (1.07 ± 0.054 v. 0.94 ± 0.054 for L and H, respectively). As suggested by the percentage of time spent with rumen pH below 6.0 (23.4 ± 6.60% v. 39.9 ± 5.88% for L and H, respectively), H was more acidogenic than L. When offered H instead of L, goats spent less time eating (298 ± 17.5 v. 265 ± 17.5 min for L and H, respectively) and ruminating (521 ± 21.0 v. 421 ± 21.0 min for L and H, respectively) but more time resting (352 ± 27.1 v. 459 ± 21.1 min for L and H, respectively) over a 24-h period. They also tended to spend more time drinking (20 ± 2.9 v. 25 ± 2.9 min for L and H, respectively; P = 0.08) when offered H rather than L. These differences in activities were mainly observed during the first hours following feeding. When offered H, goats adapted their feeding behaviour around the feedings, which allowed them to limit the physiological disturbances potentially inducible by H and to increase milk production, without experiencing too much acidosis.

[Comparison of different adjustment models of curves of fecal excretion of transit markers]. / Comparaison de différents modèles d'ajustement des courbes d'excrétion fécale des marqueurs du transit.

Seventy nine fecal excretion curves of rare earth were adjusted with 3 published models (Grovum and Williams, 1973; Dhanoa et al, 1985; Siddons et al, 1983). The models provided statistically similar estimations of particulate turnover in the first compartment and mean retention time. However, some important individual differences between parameter values could be observed from one model to another.

[Influence of the quantity of ingested dry matter and food retention time on feed digestibility in dairy goats]. / Influence de la quantité de matière sèche ingérée et du temps de séjour des aliments sur la digestibilité de la ration par la chèvre laitière.

Simultaneous measurements of organic matter digestibility (OMD) and particulate mean retention time (MRT) of diets containing various proportions of hay and concentrate (bran or beet pulp) were performed in lactating or dry goats. Beyond the hay and concentrate influences, the OMD decreased by 0.5 and 1.3 points as the dry matter intake level increased by 10 g/kg LW0.75 and MRT decreased by 5 h, respectively.