Short- and mid-term effects on performance, health and qualitative behavioural assessment of Romane lambs in different milk feeding conditions.

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.

Spatial distance and reactivity traits alter the positive perception of brushing by ewes.

Gentle handling seems to elicit positive states in sheep. The study investigated whether spatial distance alters sheep responses to brushing and whether spatial distance is influenced by reactivity. Twenty Romane ewes were assessed in three sessions: in Sessions 1 and 3, one grid separated the test animal from pen mates, with no distance between them, and in Session 2 two grids separated the test animal from pen mates by a distance of about 1.7 m. Ewes had been genetically selected for low (R-) or high (R+) behavioural reactivity to social isolation. Body postures, head orientation, ear postures, closed and half-closed eyes, tail wagging and feeding behaviour, in addition to heart rate (HR) and HR variability, as the root mean square of successive differences (RMSSD), standard deviation of all normal-to-normal (NN) intervals (SDNN), RMSSD/SDNN ratio and ratio between low-frequency (LF) and high-frequency (HF) powers (LF/HF) were assessed. Data were analysed using generalized linear models and linear mixed models. Session, genetic line and phase (pre-, brushing and post-brushing) were considered fixed effects. Increased distance in Session 2 might not have influenced ewes' responses. Fewer changes in ear postures were noted in Session 3 than 1 (P<0.01), suggesting that ewes were more relaxed in Session 3. The RMSSD/SDNN ratio was higher mainly during brushing in Sessions 1 and 3 (P<0.05), indicating that ewes were more relaxed during brushing, and at no distance between pen mates. However, spatial distance influenced R- and R+ ewes' responses; R+ ewes performed more asymmetric ear postures in Session 2 than 1 and 3 (P<0.01), and in Session 3 than 1 (P<0.01), indicating that spatial distance had a negative effect on R+ ewes. Low reactive ewes spent less time on horizontal ear postures in Session 2 than 1 and 3 (P<0.01), and R+ ewes spent more time on horizontal postures in Session 1 than 3 (P<0.01). Curiously, R- ewes spent more time eating and ruminating in Session 3 than 1 (P<0.01), and in Session 2 than 1 and 3 (P<0.01), whereas R+ ewes ate and ruminated more in Session 1 than 3 (P<0.05). Higher HR was found among R- ewes in Session 2 than 1 and 3, and in Session 3 than 1 (P<0.01). High reactive ewes showed higher HR in Session 1 than 3 (P<0.01). The findings suggest that the social context might influence sheep responses to gentle handling, and the effects depend on their reactivity traits.

Genotype by environment interactions for behavioral reactivity in sheep.

In sheep, social reactivity and reactivity to humans are relevant behavioral responses that are used to investigate the behavioral adaptation of farm animals to various rearing conditions. Such traits were previously reported as heritable and associated with several QTLs. However, few behavior-related genotype by environment (G × E) interactions have been reported to date. The experiment was performed on 2,989 male and female lambs issued from 30 sires. Every sire had progeny reared under both intensive and extensive conditions. After weaning, all lambs were individually exposed to two standardized behavioral tests. A broad range of behaviors including vocalizations, locomotion, localization, vigilance, and flight distance were assessed. Two complementary statistic approaches, with and without assumptions on the biological significance of behaviors, were performed to investigate social reactivity and reactivity to humans. G × E interactions were investigated based on the genetic correlations estimated for each factor or trait between farming conditions; those significantly different from 1 indicating a G × E. Environmental effects showed that social reactivity and reactivity to humans were higher in intensively reared lambs. The heritability of factors or traits used to measure social reactivity and reactivity to humans was similar in both rearing conditions. Estimated heritabilities were high for vocalizations in response to social isolation, moderate for locomotion and vigilance in response to social isolation, and low for both flight distance to an approaching human and proximity to a motionless human. No significant G × E interaction was found for vocalizations. G × E interactions were found for locomotion, vigilance and flight distance. Genetic correlations between both environments were low to moderate for vigilance, locomotion and flight distance. Vocalization in response to social isolation with or without human presence was identified as a robust trait and could be used to improve sheep sociability, independently of the environment. A G × E interaction was observed for behavioral reactivity to humans. Although moderate, the genetic correlation for this trait between intensive and extensive conditions could be used to select sires in the same environment by taking into account the G × E and to produce in different environments progenies that are less reactive to humans.

The valence of the long-lasting emotional experiences with various handlers modulates discrimination and generalization of individual humans in sheep.

Between-farm variation in animal reactions to humans can reflect different management styles and behavioral tendencies among farmers. Animals are well known to discriminate among humans, but less clear is the key issue of whether they more or less easily generalize their experience from specific humans to others depending on management style. Here, we chose 2 contrasted management styles by known handlers: "gentle" management, that is, long-lasting exposure to positive human interactions (with limited negative interactions), and "aversive" management including long-lasting exposure to various negative human interactions (with only food delivery considered a positive interaction) and aversive events. Over a period of 19 wk, 15 female lambs were exposed to the gentle management treatment ("gently treated" group) and another 15 lambs ("aversively treated" group) were exposed to the aversive management treatment. To facilitate discrimination by animals, experimenters wore white clothes for aversive events and green clothes for farming handling (positive handling and feeding for the gently treated group and only feeding for the aversively treated group). Sheep perception of the human was assessed after the management period by submitting lambs from each group to 2 standardized tests: 1) the presence of a stationary human (familiar human in white vs. familiar human in green vs. unknown human) and 2) the presence of a moving human (familiar human in white vs. familiar human in green vs. unknown human). As expected, during the stationary human test, aversively treated lambs spent less time in the human zone (P<0.0001), showed greater latency to approach the human (P=0.05), and had fewer contacts with the human (P=0.05) than gently treated lambs. During the moving human test, aversively treated lambs also showed a greater escape distance from humans than gently treated lambs (P<0.0001). Aversively treated lambs showed the same fear responses towards familiar and unknown humans and tended to generalize their aversive experiences with one handler to all humans. In contrast, gently treated lambs seemed to discriminate familiar humans from unfamiliar humans. Different management styles could modulate farm generalization to humans in farm animals.

Cubicle housing systems for cattle: Comfort of dairy cows depends on cubicle adjustment.

Housing is important for the welfare of cows. Although recommendations have been proposed, abnormal movements and injury problems are still observed in cubicle houses. We conducted a survey on 70 French dairy farms that used cubicles. We examined the design of the cubicles, and the behavior, injuries, and cleanliness of the cows. Most of the cubicles did not comply with the recommendations, often being too narrow and/or too short. Difficulties in lying behavior and injuries were more common when the neck rail was high. No improvement was noted when cubicles of a recent design were used ("U.S." cubicles), apparently because these cubicles were most often cantilevered on a double head rail rather than fixed on freestanding posts. An experiment was conducted, making similar measurements, on 84 cows to compare two configurations for U.S. cubicles (cantilevered on a double head rail as observed in the survey with a high and rear neck rail vs. fixed on freestanding posts as recommended) and another recent cubicle type (Euroconfort, cantilevered on head rails, but with a large space between the rails and fixed as recommended), with and without a brisket board. In U.S. cubicles on rails, cows spent more time lying and less time fully standing inside the cubicles than in the other cubicles (percentage of time: lying, 53.9 vs. 51.5; fully standing, 7.3 vs. 8.5); in Euroconfort cubicles, they hit bars more often when getting up than in U.S. Cubicles (percentage of observations: 42.4 vs. 26.4. Without a brisket board, cows lay down more often in a fore position in U.S. cubicles than in Euroconfort ones. Somatic cell counts increased with time in U.S. cubicles on rails and decreased in the other cubicles. It is suggested that the position of the neck rail in U.S. cubicles cantilevered on rails did not leave enough space for the cow to stand inside the cubicle, thereby encouraging the cow to lie down. This could in turn favor udder contamination and/or inflammation. It is concluded that the positioning of the neck rail is of prime importance, that U.S. cubicles should be used with a brisket board and with correct positioning of the neck rail (even when a head rail is used), and that leaving a large space between head rails does not offer an adequate remedial solution for keeping a free head space in front of the cubicle.

Validation of the main modeling methods for the estimation of marker mean retention times in the different compartments of the gastrointestinal tract in sheep.

Four Texel wethers (60 to 64 kg) fitted with rumen and duodenal cannulae were used to compare methods for estimating mean retention times (MRT) of digesta markers. They were fed, in eight equal meals, 1,200 g of a mixture of a chopped and ground (8-mm screen) and pelleted orchardgrass hay in the ratios 90/10, 50/50, 30/70, or 10/90 according to a 4 x 4 Latin square design. Mean retention time in the stomach and in the whole tract were estimated by orally delivering pulse doses of 170Tm-labeled chopped hay, 169Yb-labeled ground hay, and [51Cr]EDTA, followed by duodenal spot-sampling and total collection of feces; calculations were done using an algebraic method. Mean retention time in the abomasum was estimated following administration of a pulse dose of the markers (169Yb-labeled duodenal particles and [51Cr]EDTA) in the abomasum via the ruminal cannula through the reticulo-omasal orifice and collecting duodenal samples. The reference value for MRT in the reticulorumen (MRTRR) was calculated by subtracting MRT in the abomasum from MRT in the stomach. For all markers, fecal excretion curves were fitted to a two-compartment age-independent model, a gamma-2 age dependent-age independent two-compartmental model, and a multicompartmental model. Comparisons were made among parameters of the models and their anatomical or physiological attributes when these were clearly defined or easily calculated. The mean retention time in the reticulorumen (MRTRR) obtained from the multicompartment model was similar to those calculated with the algebraic method whatever the sampling site and the marker used.

Assessment of gastrointestinal permeability to small marker probes in the preruminant calf.

The intestinal permeability to markers was assessed in preruminant calves fed different milk substitutes containing skimmed milk powder or whey and soyabean products of differing antigenic activity as the protein sources. In Experiment 1, the 6 h urinary excretion of lactulose transiently decreased with the antigenic soyabean product but not that of sucrose of D-mannitol. In Experiment 2, the 6 h urinary excretion of sucrose and D-mannitol averaged 1-3%, regardless of age and dietary treatment. Cr-EDTA was recovered at rates of 2 and 4% after 6 and 24 h of urinary collection, respectively. The 24 h excretion of Cr-EDTA was lower in the calves fed the antigenic flour than in the controls after 2 weeks of experimental feeding (2.9 vs 6.0%, P < 0.05) but not thereafter. This transient decrease was also observed using D-xylose with the antigenic flour and with the non-antigenic concentrate (17 and 22% respectively vs 37%, P < 0.05). The present markers, including sucrose, may be suitable for assessing intestinal permeability in the calf even though excretion rates differed from one marker to another. Changes in the intestinal permeability to antigenic soya were of low magnitude and were only transiently detected when measured using lactulose, Cr-EDTA or D-xylose, probes which were therefore more sensitive than sucrose or D-mannitol.

Net transfer of urea and ammonia across the ruminal wall of sheep.

Texel wethers (68 +/- 2.5 kg BW) fitted with catheters in the ruminal veins and a mesenteric artery, blood flow probes on ruminal arteries, and a ruminal cannula were fed 500 g of orchardgrass hay every 12 h. During the last third of the feeding cycle, intraruminal injections were performed to evaluate the effect of urease activity, osmolality, and concentrations of NH3, butyrate, and CO2 in the rumen on urea and NH3 fluxes across the rumen wall. At pH 6.7, NH3 absorption increased with NH3 and butyrate concentrations in the rumen, and to a lesser extent with CO2 concentration. The increase in ruminal blood flow associated with CO2 and butyrate increase was always greater than the increase in NH3 absorption. Increasing ruminal osmolality slightly decreased NH3 absorption. Ruminal NH3 concentration and ruminal blood flow seemed to be the main determinant of NH3 absorption. Decreasing urease activity in the rumen decreased urea net transfer. The net transfer of urea to the rumen was stimulated by CO2. High concentrations of NH3 (330 mg of N/L) and butyrate (25 mM) in the rumen decreased urea net uptake, whereas osmolality (up to 420 mOsmol/L) did not affect it. Modifications in ruminal blood flow or water net movement across the ruminal wall did not seem to account for the effect of CO2, NH3, and butyrate on urea net uptake.

Net flux of metabolites across the ruminal wall of sheep fed twice a day with orchardgrass hay.

Four Texel wethers (68 +/- 2.5 kg BW) fitted with catheters in the ruminal veins and a mesenteric artery, blood flow probes around ruminal arteries, and a ruminal cannula were used to determine meal-related variations and daily significance of net flux across the ruminal wall of urea and ammonia (NH3), VFA, D-beta-hydroxybutyrate (D beta HOB), lactate, and glucose. Sheep were fed every 12 h with orchardgrass hay (430 g of DM/meal; 611 g of digestible OM/kg of DM and 23.6 g of N/kg of DM). Apart from lactate and glucose, the fluxes of studied metabolites were significantly affected by time after morning feeding. Maximum absorption of VFA and NH3 were observed at the end of the meal; however, 5 h after the meal VFA absorption was still high, whereas NH3 absorption had decreased to the prefeeding level. Net release of D beta HOB was greater during the 2 h after the meal than during the rest of the time. Urea net transfer decreased during the meal, and thereafter it increased to the 5th h after feeding, at which time it was twofold higher than at prefeeding. The difference in net flux across the ruminal wall of urea and NH3 was linearly correlated with NH3 concentration in the ruminal fluid. Daily urea and NH3 net transfer were -2.10 and 3.76 g of N/d, respectively. The VFA net appearance in the ruminal veins was 1.167, .226, and .014 mol/d for acetate, propionate, and butyrate, respectively. Daily net release of D beta HOB, lactate, and glucose by the rumen wall was .153, .093, and -.012 mol/d, respectively.

[Weight characteristics of digestive tissues and contents of weaned calves, in the case of 2 feed concentrates differing in the nature of nitrogenous components]. / Caractéristiques pondérales des tissus et des contenus digestifs du veau sevré, dans le cas de deux rations concentrées différant par la nature des matières azotées.

Feeding dairy calves for 13 weeks on concentrate diets differing in nitrogen degradability (pea vs soya bean meal) did not affect the fresh weight of digestive tissues and digesta at a slaughter age of 20 wk.

[Measurement of digestive transit time in the ruminant calf: comparison and validation of models for fit of the kinetics of passage]. / Mesure du transit digestif chez le veau ruminant: comparaison et validation de modèles d'ajustement des cinétiques de passage.

Three models of marker passage analysis were compared. None of them was found to be superior in fitting the data. The 3 models provided similar estimates of the mean retention time of hay in the whole digestive tract and in the rumen of calves. Discrepancies between models for other compartments are discussed in relation to sampling sites.

[Differences in nitrogen and RNA contents between free bacteria and bacteria fixed to food particles in the rumen contents, in the case of different diets; consequences for estimating the ratio of bacterial nitrogen in duodenal nitrogen]. / Différences de teneurs en azote et ARN entre les bactéries libres et les bactéries fixées aux particules alimentaires due contenu de rumen, dans le cas de différentes rations; conséquences sur l'estimation de la proportion d'azote bactérien dans l'azote duodénal.

Differences in nitrogen and RNA contents were found between liquid-associated and solid-adherent bacteria isolated from the reticulo-rumen of ruminants offered various diets. Consequences on the estimation of the bacterial nitrogen flow to the duodenum are discussed.