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International audience; High-starch diets (HSDs) fed to high-producing ruminants are often responsible for rumen dysfunction and could impair animal health and production. Feeding HSDs are often characterized by transient rumen pH depression, accurate monitoring of which requires costly or invasive methods. Numerous clinical signs can be followed to monitor such diet changes but no specific indicator is able to make a statement at animal level on-farm. The aim of this pilot study was to assess a combination of non-invasive indicators in dairy cows able to monitor a HSD in experimental conditions. A longitudinal study was conducted in 11 primiparous dairy cows fed with two different diets during three successive periods: a 4-week control period (P1) with a low-starch diet (LSD; 13% starch), a 4-week period with an HSD (P2, 35% starch) and a 3-week recovery period (P3) again with the LSD. Animal behaviour was monitored throughout the experiment, and faeces, urine, saliva, milk and blood were sampled simultaneously in each animal at least once a week for analysis. A total of 136 variables were screened by successive statistical approaches including: partial least squares-discriminant analysis, multivariate analysis and mixed-effect models. Finally, 16 indicators were selected as the most representative of a HSD challenge. A generalized linear mixed model analysis was applied to highlight parsimonious combinations of indicators able to identify animals under our experimental conditions. Eighteen models were established and the combination of milk urea nitrogen, blood bicarbonate and feed intake was the best to detect the different periods of the challenge with both 100% of specificity and sensitivity. Other indicators such as the number of drinking acts, fat:protein ratio in milk, urine, and faecal pH, were the most frequently used in the proposed models. Finally, the established models highlight the necessity for animals to have more than 1 week of recovery diet to return to their initial control state after a HSD challenge. This pilot study demonstrates the interest of using combinations of non-invasive indicators to monitor feed changes from a LSD to a HSD to dairy cows in order to improve prevention of rumen dysfunction on-farm. However, the adjustment and robustness of the proposed combinations of indicators need to be challenged using a greater number of animals as well as different acidogenic conditions before being applied on-farm.

International audience; The common practice of artificially rearing lambs from prolific meat breeds of sheep constitutes a welfare issue due to increased mortality rates and negative health issues. In this multidisciplinary study, we investigated the possible short- and mid-term advantages of artificially feeding fresh ewe's milk instead of commercial milk replacer on lambs' growth, health and welfare. Romane lambs were either separated from their mothers on D3 and fed with Lacaune ewes' milk (LAC, n = 13) or milk replacer (REP, n = 15), or they were reared by their mothers (MOT, n = 15). On D45, they were weaned, gathered in single-sex groups until the end of the study on D150. Lamb performance and biomarkers of overall health were assessed by measuring: growth, dirtiness of the perianal area, enteric pathogens in the faeces, total antioxidant status and redox status assessed by plasma reduced glutathione/oxidised glutathione ratio, and immune response after vaccination against chlamydiosis. As an exploratory approach, blood cell transcriptomic profiles were also investigated. Last, qualitative behaviour assessment (QBA) was performed as an integrated welfare criterion. Lacaune ewes' milk and REP never differed in their average daily gain but grew less than MOT lambs in the early suckling period and just after weaning. No effect was detected afterwards. On D30, LAC and REP lambs had lower total antioxidant and higher redox status than MOT lambs but did not differ among themselves. Lacaune ewes' milk and MOT had a cleaner perianal area than REP lambs on D21, while faecal pathogen infection did not vary between the treatment groups. After vaccination, LAC also had a stronger immune response on D90 compared to REP lambs. Transcriptome analysis performed on D150 showed differential gene expression, mainly in relation to inflammatory, immune and cell cycle response, between male lambs of the LAC group and those of the MOT and REP groups. Based on QBA, LAC lambs never differed from MOT lambs in their general activity and varied from REP only on D21; REP lambs were always more agitated than MOT lambs. In conclusion, artificial milk feeding impaired early growth rate, health and emotional state mainly during the milk feeding period and at weaning. Feeding artificially reared lambs with fresh ewe's milk partly mitigated some of the negative effects induced by milk replacer but without achieving the full benefit of being reared by the mother. (C) 2020 The Authors. Published by Elsevier Inc. on behalf of The Animal Consortium.

International audience; Disease and stress can disrupt the circadian rhythm of activity in animals. Sensor technologies can automatically detect variations in daily activity, but it remains difficult to detect exactly when the circadian rhythm disruption starts. Here we report a mathematical Fourier-Based Approximation with Thresholding (FBAT) method designed to detect changes in the circadian activity rhythm of cows whatever the cause of change (typically disease, stress, oestrus). We used data from an indoor positioning system that provides the time per hour spent by each cow resting, in alleys, or eating. We calculated the hourly activity level of each cow by attributing a weight to each activity. We considered 36-h time series and used Fourier transform to model the variations in activity during the first and last 24 h of these 36-h series. We then compared the Euclidian distance between the two models against a given threshold above which we considered that rhythm had changed. We tested the method on four datasets (giving a cumulative total of ~120000 cow*days) that included disease episodes (acidosis, lameness, mastitis or other infectious diseases), reproductive events (oestrus or calving) and external stimuli that can stress animals (e.g. relocation). The method obtained over 80% recall of normal days and detected 95% of abnormal rhythms due to health or reproductive events. FBAT could be implemented in precision livestock farming system monitoring tools to alert caretakers to individual animals needing specific care. The FBAT method also has the potential to detect anomalies in humans to guide healthcare intervention or in wild animals to detect disturbances. We anticipate that chronobiological studies could apply FBAT to help relate circadian rhythm anomalies to specific events.

Sickness behaviour is characterised by a lethargic state during which the animal reduces its activity, sleeps more and at times when normally awake, reduces its feed and water intake, and interacts less with its environment. Subtle modifications in behaviour can materialise just before clinical signs of a disease. Recent sensor developments enable continuous monitoring of animal behaviour, but the shift to abnormal animal activity remains difficult to detect. We explored the use of Machine Learning (ML) to detect abnormal behaviour from continuous monitoring. We submitted 14 cows (Bos taurus) to Sub-Acute Ruminal Acidosis (SARA), a disease known to induce changes in behaviour. Another 14 control cows were not submitted to SARA. We used a ruminal bolus to monitor pH and detect when a cow experienced SARA. We used a positioning system to infer an animal’s activity based on its position in relation to specific elements in the barn (feeder, resting area, and alleys). We tested several ML algorithms: K Nearest Neighbours for Regression (KNNR); Decision Tree for Regression (DTR); MultiLayer Perceptron (MLP); Long Short-Term Memory (LSTM); and an algorithm where activity is assumed to be similar from one day to the next. First, we developed ML models to predict activity on a given day from the previous 24 h, considering all cows together. Then, we calculated the error between observed and predicted values for a given cow. Finally, we compared the error to a threshold chosen to optimise the distinction between normal and abnormal values. KNNR performed best, detecting 83% of SARA cases (true-positives), but it also produced 66% of false-positives, which limits its use in practice. In conclusion, ML can help detect anomalies in behaviour. Further improvements could probably be obtained by applying ML on very large datasets at animal rather than group level.

Farmers need to detect any anomaly in animals as soon as possible for production efficiency (e.g. detection of estrus) and animal welfare (e.g. detection of diseases). The number of animals per farm is however increasing, making it difficult to detect anomalies. To help solving this problem, we undertook a study on dairy cows, in which their activity was captured by an indoor tracking system and considered as time series. The state of cows (diseases, estrus, no problem) was manually labelled by animal caretakers or by a sensor for ruminal pH (acidosis). In the present study, we propose a new Fourier based method (FBAT) to detect anomalies in time series. We compare FBAT with the best machine learning methods for time series classification in the current literature (BOSS, Hive-Cote, DTW, FCN and ResNet). It follows that BOSS, FBAT and deep learning methods yield the best performance but with different characteristics.

Les techniques d’élevage de précision ont été développées essentiellement pour augmenter la rentabilité et réduire la charge de travail en appliquant des processus automatiques de surveillance des animaux et de leur environnement. Par exemple, la détection de l’oestrus permet une insémination rapide, tandis que la détection des boiteries à un stade précoce ou d’un déséquilibre nutritionnel ou même des paramètres d’ambiance anormaux dans l’étable peuvent aider à prendre des mesures correctives rapidement. Les données générées par les capteurs pourraient également contribuer au bien-être des animaux. Un système détectant les problèmes de santé (par exemple, mammite ou cétose chez les vaches laitières) peut faire partie de la gestion du bien-être. En plus et surtout, certains dispositifs de l’élevage de précision sont basés sur la détection du comportement animal directement ou indirectement par la position des animaux : temps passé à se nourrir, ruminer, se reposer, marcher, etc. Des changements subtils de comportement peuvent indiquer l’état mental d’un animal : hyper-réactivité vs apathie, isolement social, modification du rythme quotidien d’activité, réduction du comportement de jeu ou du toilettage, hyper-agressivité. Ces changements peuvent être autant de signes de malaise dus à la maladie, au stress, à l’instabilité sociale, etc. Ainsi les techniques de l’élevage de précision offrent un large éventail de possibilités d’utiliser des signes de comportement animal pour aborder le bien-être dans des élevages modernes, qu’il s’agisse du bien-être lié à l’état de santé, aux relations sociales, aux relations Homme-animal ou à un environnement quelconque stressant. À l’heure actuelle, ces possibilités sont peu explorées. Par ailleurs, l’élevage de précision modifie le travail des agriculteurs et potentiellement leurs interactions avec les animaux. Il est nécessaire que les animaux restent au centre de l’attention si l’on veut respecter leur bien-être et ce en harmonie avec celui de l’éleveur., Precision Livestock Farming techniques have been developed essentially to increase profitability and reduce workload by applying automatic processes to monitor animals and their environment. For instance detecting oestrus allows timely insemination, while detecting lameness at an early stage or imbalance in the nutritional status or even abnormal ambiance parameters in the barn can help take remedial actions quickly. The data generated by Precision Livestock Farming sensors could also support animal welfare. A system detecting health problems (e.g. mastitis, ketosis in dairy cows) can be part of welfare management. In addition and maybe more importantly, some Precision Livestock Farming devices are based on animal behaviour detection directly, or indirectly through the position of animals: time spent feeding, ruminating, resting, walking, etc. Subtle changes in behaviour can indicate the mental state of an animal hyper-reactivity vs. apathy, social isolation, changes in the daily rhythm of activity, reduction in play behaviour and grooming, hyper-agressivity. These changes can be all signs of malaise due to disease, stress, social instability, etc. We argue that Precision Livestock Farming techniques offer a wide range of possibilities to use animal behavioural signs to address animal welfare in modern livestock farming, be the welfare related to health status, social relations, human-animal relationship or more general effects of a stressful environment. At present, these possibilities have been little explored, and they deserve more research. In addition, the use of Precision Livestock Farming is changing farmers’ work and potentially their interactions with animals. It is necessary that the animals remain at the centre of attention if one wants to address adequately their welfare in harmony with the farmer.

Rumen microbiota is of paramount importance for ruminant digestion efficiency as the microbial fermentations supply the host animal with essential sources of energy and nitrogen. Early separation of newborns from the dam and distribution of artificial milk (Artificial Milking System or AMS) could impair rumen microbial colonization, which would not only affect rumen function but also have possible negative effects on hindgut homeostasis, and impact animal health and performance. In this study, we monitored microbial communities in the rumen and the feces of 16 lambs separated from their dams from 12 h of age and artificially fed with milk replacer and starter feed from d8, in absence or presence of a combination of the live yeast Saccharomyces cerevisiae CNCM I-1077 and selected yeast metabolites. Microbial groups and targeted bacterial species were quantified by qPCR and microbial diversity and composition were assessed by 16S rDNA amplicon sequencing in samples collected from birth to 2 months of age. The fibrolytic potential of the rumen microbiota was analyzed with a DNA microarray targeting genes coding for 8 glycoside hydrolase (GH) families. In Control lambs, poor establishment of fibrolytic communities was observed. Microbial composition shifted as the lambs aged. The live yeast supplement induced significant changes in relative abundances of a few bacterial OTUs across time in the rumen samples, among which some involved in crucial rumen function, and favored establishment of Trichostomatia and Neocallimastigaceae eukaryotic families. The supplemented lambs also harbored greater abundances in Fibrobacter succinogenes after weaning. Microarray data indicated that key cellulase and hemicellulase encoding-genes were present from early age in the rumen and that in the Supplemented lambs, a greater proportion of hemicellulase genes was present. Moreover, a higher proportion of GH genes from ciliate protozoa and fungi was found in the rumen of those animals. This yeast combination improved microbial colonization in the maturing rumen, with a potentially more specialized ecosystem towards efficient fiber degradation, which suggests a possible positive impact on lamb gut development and digestive efficiency.

The aim of this study was to compare the responses in fattening performance and meat composition for high-concentrate diets rich in either starch and lipids (especially omega-3 fatty acids) or fibrous by-products. A total of 140 Charolais bulls (initially 319 ± 27 kg BW) were allocated to 3 high-concentrate diets and were fattened for up to 18 mo. The diet treatments included concentrate mixtures rich in either fiber (FR; n = 56) or starch plus linseed (diets SL and SLR; n = 56 and n = 28, respectively) and barley straw. The concentrate mix was offered ad libitum in SL and FR diets but was kept isoenergetic to the FR diet in the SLR diet. Bulls were weighed every 15 d. Feed intake was measured daily. Carcass composition was assessed for all animals slaughtered at 699 ± 65 kg BW. Meat nutritional quality traits (e.g., fat content and fatty acid composition focusing on n-6 and n-3 polyunsaturated fatty acids) were measured on the longissimus thoracis, rectus abdominis, and semitendinosus muscles. Metabolic enzyme activity (phosphofructokinase, lactate dehydrogenase, and cytochrome-c oxidase) was measured on these muscles and on liver. The SL diet bulls had greater fattening performance, BW gain (P = 0.006), and efficiency for growth (P = 0.025) at an energy intake similar to that of FR diet bulls. They also had heavier carcasses with a greater proportion of fat. However, liver samples showed no difference in specific metabolic activity. Compared to bulls fed the SL diet, bulls fed SLR consumed 15% less energy and had lower BW gain (P < 0.001) but were slightly more efficient for growth (P = 0.010). They had lower carcass weight but a greater muscle-to-fat ratio. Compared to bulls fed the FR diet, SLR bulls had lower than planned NEg intake and lower BW gain but did not have differences in body composition. Compared to the FR diet, the SL diet led to a greater omega-3 fatty acid content because of a greater supply of dietary linoleic acid, especially in lean muscle.

Biological rhythms are an essential regulator of life. There is evidence that circadian rhythm of activity is disrupted under chronic stress in animals and humans, and it may also be less marked during diseases. Here we investigated whether a detectable circadian rhythm of activity exists in dairy cows in commercial settings using a real-time positioning system. We used CowView (GEA Farm Technologies) to regularly record the individual positions of 350 cows in a Danish dairy farm over 5 nio and to infer the cows' activity (resting, feeding, in alley). We ran a factorial correspondence analysis on the cows' activities and used the first component of this analysis to express the variations in activity. On this axis, the activities obtained the following weights: resting = -0.15; in alleys = +0.12; feeding = +0.34. By applying these weights to the proportions of time each cow spent on each of the 3 activities, we were able to chart a circadian rhythm of activity. We found that average level of activity of a cow on a given clay and its variations during that day varied with specific states (i.e., estrus, lameness, mastitis). More specifically, circadian variations in activity appeared to be particularly sensitive and to vary 1 to 2 d before the farmer detected a. disorder. These findings offer promising avenues for further research to design models to predict physiological or pathological states of cows from real-time positioning data.

International audience; This study aimed to investigate the impact of repeated acidosis challenges (ACs) and the effect of live yeast supplementation (Saccharomyces cerevisiae I-1077, SC) on rumen fermentation, microbial ecosystem and inflammatory response. The experimental design involved two groups (SC, n=6; Control, n=6) of rumen fistulated wethers that were successively exposed to three ACs of 5 days each, preceded and followed by resting periods (RPs) of 23 days. AC diets consisted of 60% wheat-based concentrate and 40% hay, whereas RPs diets consisted of 20% concentrate and 80% hay. ACs induced changes in rumen fermentative parameters (pH, lactate and volatile fatty-acid concentrations and proportions) as well as in microbiota composition and diversity. The first challenge drove the fermentation pattern towards propionate. During successive challenges, rumen pH measures worsened in the control group and the fermentation profile was characterised by a higher butyrate proportion and changes in the microbiota. The first AC induced a strong release of rumen histamine and lipopolysaccharide that triggered the increase of acute-phase proteins in the plasma. This inflammatory status was maintained during all AC repetitions. Our study suggests that the response of sheep to an acidosis diet is greatly influenced by the feeding history of individuals. In live yeast-supplemented animals, the first AC was as drastic as in control sheep. However, during subsequent challenges, yeast supplementation contributed to stabilise fermentative parameters, promoted protozoal numbers and decreased lactate producing bacteria. At the systemic level, yeast helped normalising the inflammatory status of the animals.

International audience; This study aimed to investigate whether sheep offered free-choice intake of forage and concentrate develop subacute ruminal acidosis (SARA) and to identify SARA-associated feeding behavior components. In a crossover design over two 28-d periods, 11 rumen-cannulated wethers received wheat and alfalfa hay in 2 separate compartments. Concentrate and forage were provided for ad libitum access or in a fixed amount corresponding to 80% of ad libitum hay intake with a concentrate: forage ratio of 60: 40 on a DM basis. In both diets, sheep were fed 2 equal portions at 0800 and 1600 h. Ruminal pH, voluntary intake, and feeding behavior were recorded continuously from d 1 to 9 and d 15 to 23 in each period. When no measurements were performed, the animals were housed in larger pens with straw bedding. When fed for ad libitum intake, the sheep ingested 1,340 g of DM/d consisting of 49.1% wheat, whereas with the fixed diet they ate 872 g of DM/d consisting of 58.4% wheat. Sheep fed for ad libitum intake spent more time with ruminal pH < 5.6 than when fed in fixed amounts (7.77 vs. 3.05 h/d, P < 0.001). The time spent with ruminal pH < 5.6 was mainly linked to the amount of feed ingested and especially the amount of wheat (P < 0.001). Our results suggest that when fed for ad libitum intake with free choice wheat, the achieved concentrate: forage ratio of near 50: 50 and a larger hay intake enable sheep to consume more wheat. When sheep were fed for ad libitum intake, feeding bouts were spread evenly throughout the day. Although ruminal pH reached the same minimum level in both diets after main meals, time to reach pH nadir was longer with ad libitum diet (P < 0.001). In addition, after reaching this minimum value, ruminal pH increased more slowly in this diet, inducing a decreased preprandial ruminal pH (P < 0.001). Consequently, the ad libitum diet led to a longer time below pH 5.6. A slow decrease in ruminal pH may enable sheep to consume larger quantities of food. However, free access to concentrate maintains continuously elevated content of ruminal fermentation end products and so requires more time for pH to return to neutral values. Thus, interval between feed distributions should be as large as possible to help resume the preprandial ruminal pH and to limit time spent with pH < 5.6.

International audience; The activities of bulls, their feeding behaviour and their ruminal pH were examined at several stages during the finishing period, according to the forage-to-concentrate ratio of their diet. Twenty-four bulls of the Blond d’Aquitaine breed (initial body weight = 326 ± 21 kg) were assigned to six balanced pens with a space allowance of 9.4 m2 per bull during the finishing period. They were fed three different diets with achieved forage-to-concentrate ratios of (i) 8% straw and 92% concentrate, (ii) 44% hay and 56% concentrate and (iii) 57% maize silage and 43% concentrate. Bulls had ad libitum access to feed dispensed once daily. Offered and refusals were weighed on 5 consecutive days per week. The bulls were slaughtered at the common final live weight of 650 kg and the finishing period lasted 138, 181 and 155 days for straw–concentrate, hay–concentrate and maize silage–concentrate diets, respectively. The time budget was estimated four times by scan sampling with a 10-min interval. Feeding behaviour was appraised using data from electronic feeding gates. Ruminal pH was measured from a ruminal fluid sample collected by rumenocentesis. On average, the bulls spent 78% of the time lying or standing still, and 11% of the time eating. The forage-to-concentrate ratio of the diet influenced only those activities directly linked to feeding, i.e. eating and drinking. Bulls fed a high-concentrate diet spent less time eating than the other bulls (47 min v. >2 h) and took shorter meals (7 min v. 17 min). The bulls fed the straw–concentrate diet spread their meals over the entire day, whereas the others maintained two major peaks of eating activity, the main one in the morning after feed dispensing, the other one at the end of the diurnal period. Intake rate ranged widely between diets, from 58 g/min on average for the diets based on hay or maize silage up to 173 g/min for the high-concentrate diet. The concentrate-diet bulls also had a lower ruminal pH during the first 2 months of the finishing period. The dispersion of meals based on a high-acidosis-risk diet may be a way to limit the decrease in ruminal pH.

Records were collected in an experimental herd over an 11-year period from purebred Charolais heifers (n = 351), cows (n = 615) and young entire bulls (n = 383). The objective of the study was to estimate the genetic relationship between the components of female ovarian activity (age at puberty and postpartum anoestrus length), their growth rate and body condition score and beef traits measured on related bulls. Two methods were used to estimate age at puberty and postpartum anoestrus length: the detection of oestrous behaviour and a test of cyclicity based on plasmatic progesterone assay. This study shows the existence of significant heritability estimates for the different cyclicity traits (h2 between 0.11 and 0.38). Most of the genetic correlation coefficients between ovarian activity and growth rate of females and males are negative and favourable (rg between -0.43 and 0.06). Cyclicity is also favourably related with body condition score in young or adult females (rg between -0.65 and -0.22). The genetic relationship between female ovarian activity and proportion of adipose tissue in the male carcass is, however, close to zero. These results show that an antagonism between male beef traits measured in this study and female ovarian activity is unlikely to be a cause for concern in the short term.

National audience; Pour isoler les effets respectifs de la vitesse de croissance et du type de ration dans l’orientation des dépôts (muscles/dépôts adipeux) de jeunes bovins à l’engrais, une ration enrubannage de prairie permanente de semi montagne complémentée avec de la pulpe de citrus et des drèches de blé (ER) a été comparée à une ration (MPEE) ensilage de maïs complémentée en céréales (2/3 blé 1/3 maïs) et tourteau de colza. Les deux rations ont été distribuées à deux niveaux d’apports (H à volonté vs B limité) dans un dispositif 2x2 qui comprenait 36 taurillons Charolais de 360 kg répartis en 4 lots homogènes. L’amidon apporté s’élevait respectivement à 26 et 385 g/kg MS pour ER et MPEE. Les taurillons ont été abattus à un poids vif identique de 700 kg pour un poids moyen de carcasse de 420 kg. Un enregistrement individuel quotidien des quantités ingérées a été réalisé ainsi qu’un suivi du comportement alimentaire. Performances d’engraissement, rendements d’abattage et composition de la carcasse ont été mesurés. La cinétique des dépôts adipeux a été estimée par 3 mesures des adipocytes du tissu sous cutané caudal (mise en lot, milieu d’engraissement, abattage) et par l’ajustement des données disponibles à un modèle de simulation de la croissance. Les lots ER ont eu une ingestion faible au départ puis soutenue jusqu’à l’abattage. L’ingestion des lots MPEE leur était supérieure en début d’engraissement (+1 kg MSI/j par rapport aux lots ER), puis inférieure en fin (-1,5 kg MSI/j par rapport aux lots ER). Les lots ER ont réalisé des GMQ de 1400 g (B) et 1570 g (H), et les lots MPEE de 1600 g (B) et 1660 g (H). Leurs durées d’engraissement ont ainsi été de 258, 235, 213, et 202 jours. Lorsqu’au cours de l’engraissement les quantités cumulées d’énergie ingérée ont été identiques, le lot ERH était plus léger de 43 kg que le lot MPEEH et le lot ERB de 36 kg par rapport à MPEEB. Les dépôts adipeux de la carcasse (67,4 kg) et du 5ème quartier (23,8 kg) de MPEEH ont été supérieurs aux dépôts des autres lots (58 et 17 kg). Ces différences de dépôts adipeux s’observent dès le milieu d’engraissement. Ainsi, les écarts de vitesse de croissance ont eu davantage d’effet sur la dynamique des dépôts des lots MPEE qu’ER. D’un point de vue pratique, l’utilisation de l’herbe enrubannée correctement complémentée permet d’engraisser des taurillons, mais à même apport UFV mesuré, cette ration semble moins efficace en gains PV et carcasse qu’une ration basée sur l’ensilage de maïs. Son utilisation doit être raisonnée selon les conditions des ateliers d’engraissement.

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International audience; This study aims to determine whether sheep modify their feeding and general behaviour when they undergo acidosis challenge, whether these modifications are maintained when acidosis challenges are repeated and whether yeast supplementation affects these modifications. Twelve rumen-cannulated wethers fed concentrate (wheat) and forage (hay) were exposed to three 28-day periods consisting of a 23-day recovery phase (20% of wheat) followed by a 5-day acidosis challenge (60% of wheat). Both diets limited food intake to 90% of ad libitum intake. Six sheep received a daily supplementation of a live yeast product, six received a placebo. Ruminal pH was recorded continuously. Daily consumption of wheat, hay, water and weekly consumption of salt were monitored. Behavioural observations were performed twice in each period: once under the recovery phase and once under acidosis challenge. These observations included video recordings over 24 h (time budget), social tests (mixing with another sheep for 5 min) and nociception tests (CO2 hot laser). As expected, sheep spent more time with a ruminal pH below 5.6 during challenges than during recovery phases (12.5 v. 4.7 h/day). Sheep drank more water (3.87 v. 3.27 l/day) and ingested more salt (16 v. 11 g/day) during challenges. They also spent more time standing than during recovery phases, adopting more frequent alarm postures and reacting more slowly to the hot stimulus. More severe behavioural modifications were observed during the first challenge than the two other challenges. Significant concentrate refusals were observed during challenge 1: from days 3 to 5 of this challenge, sheep ate only half of the distributed concentrate. Sheep were also more active and more aggressive towards each other in challenge 1. These behavioural modifications disappeared as the challenges were repeated: no behavioural modifications were observed between challenges and recovery phases during periods 2 and 3, and furthermore, sheep rapidly ate all the concentrate distributed during the third challenge. Focusing on the effects of yeast, the only differences registered between the two groups concerned ruminal pH, that is, mean ruminal pH values in the supplemented group were lower during the first challenge (5.11 v. 5.60) but higher during the third challenge (5.84 v. 5.28). In conclusion, our experiment suggests sheep can adapt to acidosis challenges, especially with yeast supplementation. Otherwise, ruminal pH values remained low during challenges, indicating that the modifications of general and feeding behaviour in subacute ruminal acidosis situations are not due exclusively to low ruminal pH values.

International audience; Rumenocentesis is commonly used to collect rumen fluid to screen for acidosis. This study was designed to investigate whether rumenocentesis induced pain and stress and, if so, whether local anaesthesia could limit this. Twenty-four dairy cows were assigned to one of three treatments: (1) rumenocentesis with local anaesthesia (AR); (2) rumenocentesis without local anaesthesia (R); and (3) local anaesthesia only (A). Treatments were performed in a restraining cage. The cows were placed in the cage on three consecutive days and anaesthesia and/or nimenocentesis was performed on the second day. Blood samples for cortisol determination and heart rate were recorded from 0.25 h before treatment until 4 h after. Behaviour was noted while the cows were caged. Feed intake and milk production were measured the week before treatment, on the day of treatment, and the day after. With all three treatments, cortisol concentrations and heart rate were increased while cows were in the cage. Cortisol, cardiac and behavioural responses were not significantly higher in the R and AR treatments than the A group. Cortisol concentrations and heart rate did not change between days. Feed intake and milk production were unaffected by the treatments. It was concluded that rumenocentesis does not appear more stressful than local anaesthesia or handling.

Ducks (common, Muscovy and mule ducks) are the third most important bird species in animal production for human consumption worldwide. Our study aimed to improve the efficiency of mule duck breeding, thus contributing to the efficiency of food production in general. In the common duck, females can be bred either with males of the same species (i.e. in pure breeding (PB) subscript p) or in inter-generic crossbreeding (CB; subscript c) with Muscovy drakes to produce the hybrid mule duck. The aim of the present study was to estimate the genetic parameters of several indicators of duration of fertility, considered to be a trait of the female duck, within and between breeding schemes and, in particular, to estimate the purebred-crossbred genetic correlation (rg pc). These indicators were maximum duration of fertility (MD), that is, the time interval between insemination and the last fertilised egg, the number of fertile eggs (F) and of hatched ducklings (H) after a single artificial insemination (AI), and the fertility rate over days 2 to 12 after AI (F 2,12), taking three sub-periods (F 2,4, F 5,8, F 9,12) into account. A total of 494 females and 2655 inseminations were involved. PB resulted in longer duration of fertility (MD p = 8.1 v. MD c = 6.4 days). Heritability (h 2) was higher for MD p (estimate ± s.e.: 0.27 ± 0.04) than for MD c (0.15 ± 0.04), but both traits were highly correlated with each other (rg pc = 0.85 ± 0.07). F p and F c had similar heritability (h 2 around 0.24) and displayed a high genetic correlation (0.78 ± 0.07). The same was true for H p and H c (h 2 around 0.17 and rg pc = 0.88 ± 0.05). The heritability estimates were 0.24 ± 0.03 for F 2,12p and 0.20 ± 0.04 for F 2,12c, with a 0.80 ± 0.07 genetic correlation between each other. Permanent environmental effects influenced MD p far less than MD c, F p less than F c, but H p and H c to the same extent. The high values for rg pc (>0.78) indicated that the same genes are involved in the duration of fertility for both PB and CB. Unlike CB, initial fertility for PB (F 2,4p) was not correlated to overall fertility rate and to duration of fertility and probably involves different genes, if any. In both breeding schemes, indirect selection on F would be better than direct selection on H to improve H, and easier to implement than selection on MD. Moreover, any gain in one breeding scheme will have its correlated counterpart in the other one, because of the high values of rg pc.

The objective was to determine CH(4) production from bulls fed a feedlot diet rich in either fibre (F)or starch and lipid (SL) over the fattening period. Fifty six Charolais bulls (259 +/- 9.4 d of age and 339 +/- 8.2 kg live weight (LW)) were allocated randomly to one of two diets and blocked with 4 replicate pens/diet based on LW and age, and fattened for up to 18 months. Both treatments included barley straw with the appropriate concentrate mixture rich in fibre or starch and fat. The concentrate mixture and barley straw were available ad libitum, and the intake ratio (870:130: dry matter (DM)basis) for the concentrate mixture and barley straw was similar for both diets. Methane production was determined for each bull for 5 d using the sulfur hexafluoride tracer gas method at the beginning (24 d on diet +/- 3.4), middle (120 d +/- 8.2), and end (228 d +/- 11.1) of the fattening period. Feed intake was measured daily and bulls were weighed every 15 d. Ruminal fluid samples were collected on the last day of each CH(4) measurement period by rumenocentesis and measured for pH and concentrations of volatile fatty acids (VFA). Bulls fed SL had lower DM, organic matter and gross energy intake (P

International audience

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International audience

International audience; Fertility records ($n = 1 802$) were collected from 615 Charolais primiparous and multiparous cows managed in an experimental herd over an 11-year period. The objectives of the study were to describe the genetic variability of the re-establishment of postpartum reproductive activity and the relationship with body weight (BW) and body condition score (BCS) at calving and age at puberty. The length of postpartum anoestrus was estimated based on weekly blood progesterone assays and on twice daily detection of oestrus behaviour. The first oestrus behaviour was observed 69 days ($\pm 25$ days s.d.) post-calving and the first positive progesterone measurement ( $\geq 1 {\rm ng}\cdot{\rm mL}^{-1}$) was observed at 66 days ($\pm 22$ days s.d.) for the group of easy-calving multiparous suckling cows. Estimates of heritability and repeatability were $h^{2} = 0.12$ and $r = 0.38$ respectively, for the interval from calving to first oestrus (ICO). Corresponding values were $h^{2} = 0.35$ and $r = 0.60$ for the interval from calving to the first positive progesterone test (ICP). The genetic correlation between both criteria was high ($r_{g} = 0.98$). The genetic relationships between postpartum intervals and BW and BCS of the female at calving were negative: the genetic aptitude to be heavier at calving and to have high body reserves was related to shorter postpartum intervals. A favourable genetic correlation between age at puberty and postpartum intervals was found ($r_{g}$ between 0.45 and 0.70). The heifers which were genetically younger at puberty also had shorter postpartum intervals.; Variabilité génétique de la durée d'anoestrus postpartum chez la vache Charolaise et relation avec l'âge à la puberté. Des données ont été collectées pendant 11 ans en troupeau expérimental ($n = 1 802$) sur 615 vaches Charolaises primipares et multipares. Les objectifs de cette étude étaient de décrire la variabilité génétique du rétablissement de l'activité ovarienne après vêlage et sa relation avec le poids (BW) et l'état au vêlage (BCS) et l'âge à la puberté. La durée d'anoestrus postpartum a été estimée par des dosages hebdomadaires de progestérone plasmatique et une détection biquotidienne des comportements de chaleurs. Les premières chaleurs ont été détectées 69 jours ($\pm 25$ jours) après vêlage et le premier test positif de progestérone ($\geq 1 {\rm ng}\cdot{\rm mL}^{-1}$) a été observé 66 jours ($\pm 22$ jours) pour le groupe des vaches multipares allaitantes avec vêlage facile. Les estimations d'héritabilité et de répétabilité ont été $h^{2} =$ 0,12 et $r =$ 0,38 respectivement pour l'intervalle vêlage-premières chaleurs (ICO) et $h^{2} =$ 0,35 et $r =$ 0,60 pour l'intervalle vêlage-premier test positif de progestérone (ICP). La corrélation génétique entre ces deux critères était élevée ($r_{g} =$ 0,98). La relation génétique entre intervalles postpartum, note d'état corporel et poids vif des femelles au vêlage était négative. Un potentiel génétique pour être lourde au vêlage et avoir d'importantes réserves corporelles allait de pair avec des intervalles postpartum courts. Une relation génétique favorable entre les mesures de l'âge à la puberté et les intervalles postpartum a été trouvée ($r_{g}$ entre 0,45 et 0,70). Les génisses génétiquement jeunes à la puberté avaient un potentiel génétique pour des intervalles courts.

Data (n=1725) were collected from 613 primiparous and multiparous Charolais cows managed in an experimental herd over a 10-year period. The objectives of the study were to describe the variability in the re-establishment of postpartum reproductive activity. The duration of the postpartum anoestrus period was estimated from progesterone concentrations in weekly blood samples, and from daily detection of oestrous behaviour. Oestrous behaviour was first observed 71.9 days (±27.2 S.D.) post-calving, and a first positive progesterone concentration (≥1 ng/ml) was observed at 68.7 days (±25.5 S.D.). There were differences in the chronology of these events: a first positive progesterone test was detected before the first oestrus in 51% of the cases. The duration of the first oestrous (25.6±16.4 days) and ovarian (2.8±0.9 weeks) cycles varied according to the chronology of the events. Year and period of calving, calving difficulty and parity (interacting with suckling status) significantly affected the duration of the postpartum anoestrus period. These results also showed an important effect of individual female on the duration of postpartum anoestrus with a repeatability of 37% for the interval to the first oestrus and 60% for the interval to the first positive progesterone test.

Reproduction is of prime importance for the profitability of a herd, it is a prerequisite of every animal production. The breeding ability during the productive life of an animal depends on sexual maturity, fertility and prolificacy the components of which are the ovulation and the embryonic mortality rates. Those traits are studied in animal breeding and are variously taken into account in the purebred and crossbred selection schemes. Sexual maturity and prolificacy have to be improved when they are limiting factors, but for economic reasons they have to stay beneath optimal thresholds. Studying the components of prolificacy would allow a better control. Maximal fertility is always expected, but its improvement is made difficult because it depends on numerous factors : sex (female fertility is often the more limiting), reproduction technique used (natural or artificial) and the choice of the breeding period (time between littering and breeding, season). Research on genetics of the breeding traits has to be pursued, while including the recent advances in genetic cartography.; La réussite de la reproduction est primordiale pour la rentabilité de l’élevage, elle constitue un préalable indispensable à toute production. L’aptitude à la reproduction d’un animal au cours d’une carrière dépend des caractères de précocité sexuelle, de fertilité et de prolificité, cette dernière pouvant être décomposée en termes de taux d’ovulation et de mortalité embryonnaire. Ces différents aspects font l’objet de recherches en génétique animale et sont intégrés à des degrés divers dans les schémas de sélection, en race pure ou en croisement. La précocité sexuelle et la prolificité doivent être améliorées quand elles sont limitantes, mais certains seuils ne doivent pas être dépassés sous peine de voir se réduire le gain économique espéré. S’intéresser aux composantes de la prolificité devrait en permettre un meilleur contrôle. Une fertilité maximale est toujours recherchée mais elle revêt différentes facettes qui en compliquent son amélioration. Elle est à la fois dépendante du sexe (la fertilité femelle reste souvent la plus limitante) de la technique de reproduction employée (naturelle ou artificielle) et du moment choisi pour la mise à la reproduction (intervalle mise bas - reproduction, saison). Les recherches sur la génétique des caractères de reproduction doivent être poursuivies tout en intégrant les résultats de cartographie génétique.

*INRA Station d'Amélioration Génétique des Animaux 31326 Castanet-Tolosan (FRA) Diffusion du document : INRA Station d'Amélioration Génétique des Animaux 31326 Castanet-Tolosan (FRA); National audience

The accuracy and efficiency of pregnancy diagnoses in cattle by pregnancy serum protein (PSP60) radioimmunoassay, a progesterone radioimmunoassay or oestrus detection were compared. Blood samples were taken from 349 suckling heifers and cows (1,191 inseminations) at 28, 35, 50 and 90 d post-insemination for PSP60 determination and at 22-23 d for progesterone. Females were declared nonpregnant when plasma PSP60 concentration was lower than 0.2 ng/ml at 28, 35 and 50 d and 0.5 ng/ml at 90 d. When compared with rectal palpation at 90 d, the accuracy of positive (negative) diagnoses by progesterone assay was 80% (100%) in heifers and 75% (99%) in cows. The accuracy of positive diagnoses by PSP60 assay increased with gestation stage from 90% on d 28 in heifers (74% in cows) to 100% (99% in cows) at the time of rectal palpation. This accuracy was 84% on d 28 in cows when the interval from calving to blood sampling was higher than 115 d. Whatever the stage, the accuracy of negative diagnoses was higher than 90%. Efficiency in detecting pregnant or nonpregnant females on d 28 was equivalent to the progesterone assay. The method for detecting oestrus applied in this experiment was as efficient as the PSP60 or progesterone test at any stage of gestation. The PSP60 test is very flexible, which makes its use particularly interesting in naturally mated suckling herds because of the uncertainty regarding the date of fertilization.

In order to have a specific marker for studying pregnancy in cattle we examined the characteristics of a pregnancy serum protein produced by the placenta (PSP60). Its profile in peripheral blood was determined by radioimmunoassay in pregnant cows of 3 breeds after artificial insemination (AI): Charolais (n = 24), Normande (n = 24) and Holstein (n = 26). From 27 d post-AI to the end of pregnancy the plasma PSP60 concentration increased, especially during the last 2 wk, to reach a peak a few d before calving, which was higher (P < 0.001) in the Charolais (1,238 +/- 422 ng/ml) than in the other breeds (528 +/- 458 and 444 +/- 204 ng/ml). With an apparent half-life of approximately 8 d, this protein was still detectable in the maternal blood from 105, 85 and 87 d post-partum in the Charolais, Normande and Holstein breeds, respectively. Fertility results on 1,102 inseminations in the Charolais breed showed that the PSP60 concentration dropped then disappeared after embryonic mortality. Sequential assays of this protein between 28-90 d after AI are useful for studying the course of pregnancy, although they do not allow discrimination between early embryonic mortality and non-fertilization which together constitute 75% of pregnancy failures.

International audience

National audience; Dans un troupeau expérimental en race Charolaise, la puberté des génisses est déterminée par dosages sériques de la progestérone entre les âges de 11 et 20 mois. Après engraissement, les taurillons sont abattus à 15 ou 19 mois. Leur composition corporelle est estimée et leurs testicules sont pesés. Un total de 328 génisses et 358 taurillons, issus de 60 pères, a été contrôlé de 1989 à 1994. L’héritabilité des caractères relatifs la puberté n’est pas négligeable (h2=0,21-0,26), quoique nettement plus faible que celle des caractères de croissance ou d’abattage des taurillons (h2=0,39-0,50). Génétiquement, les génisses ayant un potentiel de croissance élevé ont tendance à être pubères plus jeunes. Il n’apparaît pas d’opposition génétique entre la croissance musculaire des taurillons et la précocité sexuelle des génisses. Le poids des testicules des taurillons est génétiquement indépendant de l’âge à la puberté des génisses.

International audience; Feeding late maturing young bulls on high concentrate diets needs adjustment of both animal feeding behaviour and rumen adaptation which can be done by feeding maize silage according to researchers at the National Institute of Agronomic Research, Saint-Genès Champanelle, France who state good economic results are achievable alongside animal welfare.

Methanogenesis plays an important role in maintaining low hydrogen partial pressure in the rumen and consequently in feed digestion. Diet composition and lipid supplementation are known to influence the extent of methane (CH 4 ) production in ruminants. However, the impact of diet composition on rumen methanogens is poorly understood. This study examined CH 4 production and methanogen community abundance, diversity and metabolic activity in the rumen of fattening bulls fed a fibrous diet (F; n = 10) or a starch rich diet supplemented with extruded linseed (SL; n = 10). Net CH 4 emissions from bulls fed SL were lower than emissions from bulls fed F. Methanogenic Archaea were studied using culture independent methods targeting the functional mcrA gene. Methanogen abundance was similar in the two groups of bulls, but protozoa numbers were 65% lower in the F group. The SL diet decreased methanogen diversity and metabolic activity, which were evaluated by PCR-DGGE and reverse transcriptase qPCR, respectively. In contrast, no changes occurred in bacterial numbers and diversity between diets. Data indicate that reduction in net CH 4 production with the SL diet was associated with changes in rumen microbiota, particularly methanogen activity. Characterization of the activity and structure of the whole rumen microbiota should provide a better prediction of methanogenesis. This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

In an experimental Charolais herd of 351 heifers, the establishment of puberty was described through 2 monthly blood progesterone assays at 10-day intervals and daily oestrus obser- vations between 10 and 20 months of age. At 15 months of age, 72 % of the heifers exhibited an oestrous behaviour, 56 % a positive progesterone assay and 53 % the two events. The mean age and weight at the first oestrus were 426 ± 42 days and 406 ± 38 kg (respectively, 445 ± 43 days and 418 ± 36 kg at the first positive progesterone test). Environmental factors influencing age at puberty were identified: year and period of birth, age of dam and twinning birth. Some of these factors act through an effect on the growth rate of the heifer. When data were adjusted for these factors, a mod- erate favourable phenotypic relationship still existed between growth rate and puberty-related traits. (© Elsevier / Inra)