Relationships between early experience to dietary diversity, acceptance of novel flavors, and open field behavior in sheep

Review: A theoretical framework to define foraging behaviour syndromes in ruminants using wearable technologies

Due to intensification processes that have had negative impacts on environmental externalities, pastoral farmers, worldwide, are facing increasing scrutiny and pressure from consumers, governments, and the public to reduce the environmental footprint of their operations. Developing tools and systems that farmers can use to maintain profitability and productivity while decreasing the negative externalities of their operations is important for the vitality of rural sectors. Capitalising on individual animal variation has been promoted as an opportunity to increase animal productivity and enhance welfare while decreasing the negative environmental impacts of pastoral farming. Of particular interest are behaviours that are associated with foraging, as these are the primary drivers of variation in animal performance in pastoral farming. Developing a methodology that can identify consistent foraging behavioural variations across individuals is a critical step in making this a practical solution for farmers and herders. As with all behavioural research, the fundamental challenge is selecting the appropriate behaviours to measure. Understanding the contextual drivers of behavioural expression is a major development in this process. Herd management and composition, environmental variables and many more contexts alter the expression of behaviours, so how do we capture behaviours of interest? We propose the use of a systematic methodology to capture behaviours of significance from large groups of foraging ruminants using wearable technology, namely Global Positioning System and accelerometers. This contrasts with traditional reductionist methodologies used in behaviour research and has the benefit of providing large objective datasets from undisturbed animals. Statistical analysis of the data will inform behaviours of interest that are clustered together to inform a three-factor foraging behaviour syndrome model adapted from the animal five-factor model (activity, aggression, boldness, exploration, sociability) of personality. Syndromes, unlike personalities, include correlated suites of behaviours that are expressed across spatial and temporal contexts. By capturing foraging behaviour syndromes, selection can be used to match appropriate syndromes to different pastoral farming landscapes, thereby potentially improving the system's productivity while reducing their negative environmental impact.

Effects of flavour variety on the intake and palatability of commercial feed in nursery pigs

Sensory-specific satiety (SSS) could negatively affect pigs' feed intake, even when diets satisfy their nutritional requirements. We evaluated the short-term effects of SSS on feed intake and palatability. Thirty-two nursery pigs (tested in pairs) were exposed to short-term feeding trials for 6 days. In Trial 1, animals received for 90 min over three consecutive days three feeders: with different flavours (VAR); the same flavour (MON); or a mixture of the three flavours (MIX) in a 3 × 3 Latin square design. In Trial 2, with the same animals and different flavours, the three feeders were delivered successively (1 feeder every 30 min). In Trial 1, there was a day-by-diet interaction (F 4,36 = 2.98; p = 0.032), where the VAR diet was least consumed on the first day but most consumed subsequently. In Trial 2 a triple interaction between diet, day and delivery order modified pig's intake (F 12,15 = 3.33; p = 0.015), and consumption patterns (F 12,15 = 3.52; p = 0.012); where VAR diet presented the highest values in the last delivery order on the third experimental day. Flavour variety may decrease the effect of SSS, increasing feed intake and hedonic value in nursery pigs when there was a previous experience with those flavours.

Grazing diverse combinations of tanniferous and nontanniferous legumes: implications for foraging behavior, performance, and hair cortisol in beef cattle

A diversity of forages with different types and concentrations of nutrients and plant secondary compounds may lead to complementary relationships that enhance cattle performance and welfare. We determined whether grazing combinations of tanniferous legumes (Lotus corniculatus, birdsfoot trefoil [BFT], Onobrychis viciifolia, sainfoin [SF]), and alfalfa [ALF] (Medicago sativa) influence foraging behavior, performance, and hair cortisol concentration in beef cattle compared with grazing the same legumes as monocultures. Twenty-one pairs of heifers grazed three spatial replications of seven treatments: monocultures of BFT, SF, or ALF, and all possible two- and three-way choices among strips of these legumes: SF-BFT, ALF-BFT, ALF-SF, and ALF-SF-BFT in two periods of 25 d each (adaptation phase + experimental period) during two consecutive years. The lowest incidence of grazing events occurred in the BFT treatment (42.0% of the total scans recorded; P < 0.10), with the rest of the treatments ranging between 47.8% (SF-BFT) and 52.6% (ALF-SF) of the total scans recorded. Heifers selected a varied diet, preferring SF over BFT or ALF in a 46:27:27 ratio for the three-way choice, and in a 70:30 ratio for both two-way choices. Heifers preferred BFT over ALF (62:38 ratio) in a two-way choice. All treatments followed similar daily grazing patterns (P > 0.10), with two major grazing events (1 h after sunrise and 3 h before dark). No differences among treatments were observed for the number of steps taken by heifers on a daily basis, motion index, or the percentage of time heifers spent standing (1,599, 5,356, and 45.3%, respectively; P > 0.10), suggesting that heifers on choice treatments did not invest extra time in walking, searching, or patch switching activities relative to heifers grazing monocultures. Heifers grazing the three-way choice gained more body weight (1.27 kg/d) than the average gains observed for animals grazing in all legume monocultures (1.00 kg/d; P = 0.014) or two-way choices (0.97 kg/d; P = 0.007), suggesting a synergism among pasture species for the treatment with the highest diversity. No differences in hair cortisol concentration were observed among treatments, with values ranging between 1.4 (BFT) and 2.12 ng/g (three-way choice; P > 0.10). Thus, forage diversity has the potential to enhance animal performance without affecting grazing efficiency, likely explained by the spatial arrangement of the forage species presented in the study.

Animal Design Through Functional Dietary Diversity for Future Productive Landscapes

Pastoral livestock production systems are facing considerable societal pressure to reduce environmental impact, enhance animal welfare, and promote product integrity, while maintaining or increasing system profitability. Design theory is the conscious tailoring of a system for a specific or set of purposes. Then, animals—as biological systems nested in grazing environments—can be designed in order to achieve multi-faceted goals. We argue that phytochemical rich diets through dietary taxonomical diversity can be used as a design tool for both current animal product integrity and to develop future multipurpose animals. Through conscious choice, animals offered a diverse array of plants tailor a diet, which better meets their individual requirements for nutrients, pharmaceuticals, and prophylactics. Phytochemical rich diets with diverse arrangements of plant secondary compounds also reduce environmental impacts of grazing animals by manipulating the use of C and N, thereby reducing methane production and excretion of N. Subsequently functional dietary diversity (FDD), as opposed to dietary monotony, offers better nourishment, health benefits and hedonic value (positive reward increasing “liking” of feed), as well as the opportunity for individualism; and thereby eudaimonic well-being. Moreover, phytochemical rich diets with diverse arrangements of plant secondary compounds may translate in animal products with similar richness, enhancing consumer human health and well-being. Functional dietary diversity also allows us to design future animals. Dietary exposure begins in utero, continues through mothers' milk, and carries on in early-life experiences, influencing dietary preferences later in life. More specifically, in utero exposure to specific flavors cause epigenetic changes that alter morphological and physiological mechanisms that influence future “wanting,” “liking” and learning of particular foods and foodscapes. In this context, we argue that in utero and early life exposure to designed flavors of future multifunctional foodscapes allow us to graze future ruminants with enhanced multiple ecosystem services. Collectively, the strategic use of FDD allows us to “create” animals and their products for immediate and future food, health, and wealth. Finally, implementing design theory provides a link between our thoughtscape (i.e., the use of FDD as design) to future landscapes, which provides a beneficial foodscape to the animals, an subsequently to us.

How Dietary Diversity Enhances Hedonic and Eudaimonic Well-Being in Grazing Ruminants

Ruminants evolved in diverse landscapes of which they utilized, by choice, a diverse arrangement of plants (grasses, forbs, and trees) for food. These plants provide them with both primary (carbohydrates, protein, etc.) and secondary (phenolics, terpenes, etc.) compounds (PPC and PSC, respectively). As no one plant could possibly constitute a “balanced-diet,” ruminants mix diets so that they can exploit arrangements of PPC to meet their individual requirements. Diet mixing also allows for ruminants to ingest PSC at levels, acquiring their benefits such as antioxidants and reduced gastrointestinal parasites, without overstepping thresholds of toxicity. Meeting dietary requirements is assumed to provide satisfaction through achieving positive internal status and comfort, thereby a sense of hedonic (happiness through pleasure) well-being. Furthermore, choice including dietary choice is a factor influencing well-being of ruminants in a manner akin to that in humans. Choice may facilitate eudaimonic (happiness through pursuit of purpose) well-being in livestock. Nutritional status plays an integral role in oxidative stress, which is linked with illness. Several diseases in livestock have been directly linked to oxidative stress. Mastitis, metritis, hypocalcaemia, and retained placenta occur in animals transitioning from dry to lactating and have been linked to oxidative stress and such a stress has likewise been linked to diseases that occur in growing livestock as well, such as bovine respiratory disease. The link between physiological stress and oxidative stress is not well-defined in livestock but is evident in humans. As dietary diversity allows animals to select more adequately balanced diets (improved nutrition), take advantage of PSC (natural antioxidants), and allows for choice (improved animal well-being) there is a strong possibility for ruminants to improve their oxidative status and thus health, well-being, and therefor production. The purposes of this review are to first, provide an introduction to oxidative and physiological stress, and nutritional status as effected by dietary diversity, with special attention to providing support and on answering the “how.” Second, to provide evidence of how these stresses are connected and influence each other, and finally discuss how dietary diversity provides a beneficial link to all three and enhances both eudaimonic and hedonic well-being.

Conditions for assessing cortisol in sheep: the total form in blood v. the free form in saliva

Cortisol is often used as a stress indicator in animal behaviour research. Cortisol is commonly measured in plasma and can also be measured in saliva. Saliva contains only the free form of cortisol, which is biologically active, and saliva sampling is not invasive and may therefore be less stressful. Our study aims to guide the choice between the measurements of cortisol in plasma v. saliva depending on experimental conditions. We analysed the effect of the level of cortisol in plasma on the concentration of cortisol in saliva compared to plasma and the effect of saliva sampling v. jugular venepuncture on the cortisol response. In Experiment 1, blood and saliva were collected simultaneously under conditions in which the expected cortisol release in blood varied: in an undisturbed situation or after the isolation of lambs from their pens or the administration of exogenous ACTH (six animals per treatment). In Experiment 2, we subjected lambs to saliva sampling, venepuncture or neither of these for 8 days to evaluate how stressful the sampling method was and whether the animals habituated to it by comparing the responses between the first and last days (four animals per treatment). All animals were equipped with jugular catheters to allow regular blood sampling without disturbance. Samples were collected 15 min before any treatment was applied, then at various time points up to 135 min in Experiment 1 and 45 min in Experiment 2. In Experiment 1, we observed a strong correlation between salivary and plasma cortisol concentrations (r = 0.81, P < 0.001). The ratio between salivary and plasma cortisol concentrations was 0.106 on average. This ratio was higher and more variable when the cortisol concentration in plasma was below 55 nmol/l. In Experiment 2, venepuncture induced a larger cortisol response than saliva sampling or no intervention on day 1 (P < 0.02); this difference was not observed on day 8, suggesting that sheep habituated to venepuncture. We recommend the measurement of cortisol in saliva to avoid stressing animals. However, when the expected concentration in plasma is below 55 nmol/l, the cortisol in saliva will reflect only the free fraction of the cortisol, which may be a limitation if the focus of the experiment is on total cortisol. In addition, if cortisol is measured in plasma and blood is collected by venepuncture, we recommend that sheep be habituated to venepuncture, at least to the handling required for a venepuncture.

A Case for Eustress in Grazing Animals

Herbivores grazing in extensive systems are exposed to a series of challenges, rooted in the inherent spatial and temporal variability of their environment that potentially constrain their health, nutrition, and welfare. Nevertheless, in this review, we argue that challenges induced by some biotic (e.g., vegetation) and abiotic (e.g., terrain) factors may also be viewed as "positive" sources of stress or eustress, since they present complex problems, that when solved successfully elicit a greater degree of behavioral plasticity and adaptability in grazing animals. Chemically and structurally diverse landscapes require animals to display complex behaviors and exhibit adaptive capabilities, like building a balanced and safe diet or finding shelter, which ultimately lead to positive emotional states. Thus, maintaining or enhancing the diversity occurring in natural systems represent a management approach that can be used to improve welfare and prepare the animal for an efficient adaptation to future, and potentially unknown, environmental challenges.

Effects of milk replacer acidification and free-access feeding on early life feeding, oral, and lying behavior of dairy calves

Acidification is a practical way of preserving the bacteriological quality of milk so that it can be fed to calves under free-access conditions. The objectives of this study were to evaluate how milk replacer acidification and free-access feeding affect dairy calf behavior during the first week of life. Sixteen Holstein male calves were purchased at birth and transported to the University of Guelph Kemptville Campus Dairy Education and Research Centre. Calves were randomly assigned to 1 of 4 milk feeding programs: (1) free-access (ad libitum) feeding of acidified milk replacer (22% crude protein and 17% fat, 150 g/L; FA); (2) restricted (6 L/d, 150 g/L) feeding of acidified milk replacer (RA); (3) free-access feeding of nonacidified milk replacer (FN); and (4) restricted feeding of nonacidified milk replacer (RN). Formic acid was used to acidify milk replacer to a target pH between 4.0 and 4.5. Video recordings of each calf at 1, 2, and 6 d were analyzed continuously over 24 h for all occurrences of each behavior in the ethogram. Feeding behavior observations were organized into sucking bouts, from which feeding behavior outcome variables were calculated. Calves consuming acidified milk replacer demonstrated more fragmented feeding patterns, characterized by more pauses within a sucking bout (FA, FN, RA, and RN calves = 12.4, 4.4, 13.7, and 11.9 pauses/bout, respectively) and longer sucking bout duration (FA, FN, RA, and RN calves = 8.8, 5.2, 9.3, and 8.1 min/bout, respectively), than calves fed nonacidified milk replacer. Restricted-fed calves tended to have longer sucking bouts and performed more within-bout sucks (FA, FN, RA, and RN calves = 10.7, 5.8, 13.5, and 14.1, respectively) and pauses than free-access calves. Acidification and free-access feeding did not affect lying duration. Calves assigned to the acidified feeding treatments tended to perform more grooming behavior than those fed nonacidified milk replacer (FA, FN, RA, and RN calves = 0.9, 0.5, 0.8, and 0.6 h/d, respectively). Free-access feeding did not affect grooming duration. The observed differences in feeding and grooming behavior suggest that acidification to a pH between 4.0 and 4.5 may have altered the palatability of milk replacer. Calves assigned to the acidified milk replacer feeding treatments did not, however, show avoidance toward this feedstuff during the first week of life.

Grazing management: setting the table, designing the menu and influencing the diner

Pastoral livestock-production systems are under increasing environmental, social and consumer pressures to reduce environmental impacts and to enhance biodiversity and animal welfare. At the same time, farmers face the challenge of managing grazing, which is intimately linked with profitability. Recent advances in understanding grazing patterns and nutritional ecology may help alleviate such pressures. For instance, by managing grazing to (1) manipulate links between ingestive–digestive decisions and temporal patterns of nutrient excretion, (2) provide phytochemically diverse diets at appropriate temporal (the menu) and spatial (the table) scales and (3) influence the behaviour of animals (the diners) on the basis of their specific ‘personalities’ and needs, to overcome or enhance animal differences, thereby enhancing their and farm productivity and welfare, as well as our health. Under pastoral systems, synergies between animals’ and farmers’ grazing decisions have the potential to offer greater benefits to the animal, the environment and the farm than does simple and parsimonious grazing management based on a single component of the system. In the present review, we look at grazing and its management through an alternate lens, drawing ideas and hypotheses to stimulate thinking, dialogue and discussions that we anticipate will evolve into innovative research programs and grazing strategies. To do so, we combined experimental and observational studies from a wide range of disciplines with simulation-modelling exercises. We envisage a more holistic approach to manage grazing based on recent advances in the understanding of the nutritional ecology of grazing animals, and propose management practices that may enable pastoral livestock-production systems to evolve continually as complex creative systems.

How to Create Conditioned Taste Aversion for Grazing Ground Covers in Woody Crops with Small Ruminants

Conditioned taste aversion (CTA) is a learning behavior process where animals are trained to reject certain feed after gastrointestinal discomfort has been produced. Lithium chloride (LiCl) is the preferred agent used in livestock to induce CTA because it specifically stimulates the vomit center. In addition, LiCl is commercially available, and easy to prepare and administer using a drenching gun. Nevertheless, some factors have to be considered to obtain an effective long-lasting CTA, which allows small ruminants to graze during the cropping season. A key aspect is to use animals with no previous contact with the target plant (the plant chosen to be avoided; new feed). Due to their native neophobic feeding behavior, small ruminants can easily associate the negative feedback effects with the new feed, resulting in a strong and persistent CTA. The recommended doses are 200 and 225 mg LiCl/kg body weight (BW) for goats and sheep, respectively. To induce CTA, 100 g of the target plant should be individually offered for at least 30 min, and LiCl administered thereafter if the intake is greater than 10 g. Each time the animal eats the target plant without negative consequences, the CTA becomes weaker. Consequently, to minimize the risk of target plant consumption, it is essential to have sufficient palatable ground cover available. The presence of an alternative feed (of quality and quantity) prevents the accidental consumption of the target plant. A close monitoring of the flock is recommended to remove and re-dose any animal consuming more than 4 bites or 10 g of the target plant. At the beginning of each grazing season, check the CTA status of each animal before moving them to the crop.

Feeding behaviour in ruminants: a consequence of interactions between a reward system and the regulation of metabolic homeostasis

Feeding behaviour, through both diet selection and food intake, is the predominant way that an animal attempts to fulfil its metabolic requirements and achieve homeostasis. In domestic herbivores across the wide range of production practices, voluntary feed intake is arguably the most important factor in animal production, and a better understanding of systems involved in intake regulation can have important practical implications in terms of performance, health and welfare. In this review, we provide a conceptual framework that highlights the critical involvement and interconnections of two major regulatory systems of feeding behaviour: the reward and the homeostatic systems. A review of the literature on ruminants and rodents provides evidence that feeding behaviour is not only shaped by homeostatic needs but also by hedonic and motivational incentives associated with foods through experiences and expectations of rewards. The different brain structures and neuronal/hormonal pathways involved in these two regulatory systems is evidence of their different influences on feeding behaviours that help explain deviation from behaviour based solely on satisfying nutritional needs, and offers opportunities to influence feeding motivation to meet applied goals in livestock production. This review further highlights the key contribution of experience in the short (behavioural learning) and long term (metabolic learning), including the critical role of fetal environment in shaping feeding behaviour both directly by food cue–consequence pairings and indirectly via modifications of metabolic functioning, with cascading effects on energy balance and body reserves and, consequently, on feeding motivation.

Understanding and manipulating diet choice in grazing animals

Conventional models of foraging, such as optimal foraging theory, generally take the univariate approach to explain the decisions of consumers on the basis of the intrinsic properties of foods, including nutrient concentration and abundance. However, the food environment is inherently diverse and, as a consequence, foraging decisions are influenced by the interactions among multiple food components and the forager. Foraging behaviour is affected by the consumer’s past experiences with the biochemical context in which a food is ingested, including the kinds and amounts of nutrients and plant secondary compounds in a plant and its neighbours. In addition, past experiences with food have the potential to influence food preference and intake through a mechanism, namely, food hedonics, which is not entirely dependent on the classical homeostatic model of appetite control. Research on the impacts of experience with food context and its behavioural expression in natural settings should pioneer innovative management strategies aimed at modifying food intake and preference of herbivores to enhance their nutrition, health and welfare, as well as the health and integrity of the landscapes they inhabit.

Food sensory characteristics: their unconsidered roles in the feeding behaviour of domestic ruminants

When domestic ruminants are faced with food diversity, they can use pre-ingestive information (i.e. food sensory characteristics perceived by the animal before swallowing the food) and post-ingestive information (i.e. digestive and metabolic consequences, experienced by the animal after swallowing the food) to evaluate the food and make decisions to select a suitable diet. The concept of palatability is essential to understand how pre- and post-ingestive information are interrelated. It refers to the hedonic value of the food without any immediate effect of post-ingestive consequences and environmental factors, but with the influence of individual characteristics, such as animal's genetic background, internal state and previous experiences. In the literature, the post-ingestive consequences are commonly considered as the main force that influences feeding behaviour whereas food sensory characteristics are only used as discriminatory agents. This discriminatory role is indeed important for animals to be aware of their feeding environment, and ruminants are able to use their different senses either singly or in combination to discriminate between different foods. However, numerous studies on ruminants' feeding behaviour demonstrate that the role of food sensory characteristics has been underestimated or simplified; they could play at least two other roles. First, some sensory characteristics also possess a hedonic value which influences ruminants' intake, preferences and food learning independently of any immediate post-ingestive consequences. Further, diversity of food sensory characteristics has a hedonic value, as animals prefer an absence of monotony in food sensory characteristics at similar post-ingestive consequences. Second, some of these food sensory characteristics become an indicator of post-ingestive consequences after their initial hedonic value has acquired a positive or a negative value via previous individual food learning or evolutionary processes. These food sensory characteristics thus represent cues that could help ruminants to anticipate the post-ingestive consequences of a food and to improve their learning efficiency, especially in complex environments. This review then suggests that food sensory characteristics could be of importance to provide pleasure to animals, to increase palatability of a food and to help them learn in complex feeding situations which could improve animal welfare and productivity.