Browsing by Author "Figueroa, Jaime"

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    Biochemical and Genomic Characterization of the Cypermethrin-Degrading and Biosurfactant-Producing Bacterial Strains Isolated from Marine Sediments of the Chilean Northern Patagonia
    (2020) Aguila-Torres, Patricia; Maldonado, Jonathan; Gaete, Alexis; Figueroa, Jaime; Gonzalez, Alex; Miranda, Richard; Gonzalez-Stegmaier, Roxana; Martin, Carolina; Gonzalez, Mauricio
    Pesticides cause severe environmental damage to marine ecosystems. In the last ten years, cypermethrin has been extensively used as an antiparasitic pesticide in the salmon farming industry located in Northern Patagonia. The objective of this study was the biochemical and genomic characterization of cypermethrin-degrading and biosurfactant-producing bacterial strains isolated from cypermethrin-contaminated marine sediment samples collected in southern Chile (MS). Eleven strains were isolated by cypermethrin enrichment culture techniques and were identified by 16S rDNA gene sequencing analyses. The highest growth rate on cypermethrin was observed in four isolates (MS13, MS15a, MS16, and MS19) that also exhibited high levels of biosurfactant production. Genome sequence analyses of these isolates revealed the presence of genes encoding components of bacterial secondary metabolism, and the enzymes esterase, pyrethroid hydrolase, and laccase, which have been associated with different biodegradation pathways of cypermethrin. These novel cypermethrin-degrading and biosurfactant-producing bacterial isolates have a biotechnological potential for biodegradation of cypermethrin-contaminated marine sediments, and their genomes contribute to the understanding of microbial lifestyles in these extreme environments.
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    Do Domestic Pigs Acquire a Positive Perception of Humans through Observational Social Learning?
    (2021) Luna, Daniela; Gonzalez, Catalina; Byrd, Christopher J.; Palomo, Rocio; Huenul, Elizabeth; Figueroa, Jaime
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    Effect of switching sows' positions during lactation on suckling behaviour and performance of co-mingling piglets
    (ELSEVIER, 2021) Guzman Pino, Sergio A.; Luna, Daniela; Salazar, Laura C.; Poblete Grez, Paulina; Figueroa, Jaime
    Under natural conditions, piglets have the opportunity to interact with non-littermates before weaning. Nevertheless, in intensive production systems, piglets only have contact with penmates during lactation. Social interactions can be encouraged by removing the barrier between litters whilst the sows are kept in their own crates. However, when piglets are co-mingled at the first days of lactation, studies have shown that a high percentage of them suck with their own mother during all the suckling period, regardless of nipples availability. This study aimed to investigate the effect of switching sows' positions between early co-mingled litters on suckling episodes, durations and maternal suckling. Eight sows' pairs were housed in adjacent pens before farrowing. Piglets were socialized by removing the separating barriers between two adjacent pens on day 2 post-farrowing. The position of four sows' pairs was switched at day 14 post-farrowing (Switched group), while the remaining four sows' pairs remained in their original crates (Control group). The suckling behaviour of piglets was video recorded during the whole experiment (day 2-23). After sows were switched, a decrease suckling duration was observed in Switched group (P = 0.015), a situation that was also observed when analysing one day before and after the change in position. (P = 0.018). The number of suckling episodes decreased in both groups (P < 0.001) after sows were switched. However, when analysing one day before and after switching the number of suckling episodes increased (P 0.001). Maternal suckling decrease in both groups after sows were switched (P = 0.013). However, no differences were observed one day before and after the switching of sows. No effect of switching sows' position was observed on productive parameters of piglets (P 0.05). The suckling behaviour in early comingled piglets slightly change after the sows' position was switched at an intermediate stage of lactation. A decrease in the suckling duration and an increase in the number of episodes one day after sows were switched probably reflect a momentary confusion of the animals. However, although there may have been operant conditioning at the site of consumption, this was not enough to significantly reduce maternal suckling in contrast with previous literature that separated barriers at the middle of the suckling period, reinforcing the operant conditioning through a greater period of conditioning experience.
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    Effects of trial and error and social learning on flavour palatability in nursery pigs
    (2021) Figueroa, Jaime; Luna, Daniela; Salazar, Laura C.; Morales, Pia; Valdivia, Catalina; Mueller, Maximiliano; Dwyer, Dominic
    The acquisition of behaviours that enhance the acceptability of new feeds could improve the performance and animal welfare in the pig industry. Pigs may learn individually by trial and error and/or by social learning to consume and prefer new flavoured feeds. However, there is little information regarding the effects of learning on the palatability of those flavours. This study aimed to investigate possible changes in pigs? hedonic responses, estimated by the mean consumption time per approach (CT/A), for flavours previously learnt through individual experiences (Experiment 1) and socially by a brief interaction with an experienced conspecific (Experiment 2). A total of 96 nursery pigs were used to study their preference, acceptability and palatability for flavours previously learnt about. Flavours were associated with 4% sucrose (Experiment 1) or with a demonstrator that recently consumed the flavour (Experiment 2). Those flavours or positive conditioned stimulus (CS+) were compared with control flavours that were not positively conditioned (CS-). In experiment 1, pigs preferred (P = 0.010) and tended to accept more (P = 0.069) of the CS + than CS- in water solutions. Nevertheless, no palatability differences were found (P = 0.875). In experiment 2, observer animals had a higher intake of CS + following interaction with demonstrators that consumed the same flavoured feed (P = 0.041). Snout to snout interaction time between those demonstrators and observers tended to present a positive correlation with CT/A (r = 0.497, P = 0.1). Thus both individual trial and error learning, and social learning, increased pigs acceptance of, and preference for, food flavours. However, only social learning modified the pattern of consumption with the observation of a correlation between changes in the CT/A ratio and the degree of snout to snout contact time between demonstrators and observers. Thus the mechanisms and effects of social and individual learning appear to differ at least partially. Regardless of mechanism, the fact that associative learning can increase food flavour consumption suggests that interventions based on associative learning may be beneficial for addressing welfare problems in pig production linked to low consumption, in particular with respect to weaning where the low consumption may relate to the inexperience of the animals.
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    Exploring Anhedonia in Kennelled Dogs: Could Coping Styles Affect Hedonic Preferences for Sweet and Umami Flavours?
    (2020) Luna, Daniela; Carrasco, Carolina; Alvarez, Daniela; Gonzalez, Catalina; Ignacio Egana, Juan; Figueroa, Jaime
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    Food Preferences in Dogs: Effect of Dietary Composition and Intrinsic Variables on Diet Selection
    (2019) Alegria-Moran, Raul A.; Guzman-Pino, Sergio A.; Ignacio Egana, Juan; Munoz, Carem; Figueroa, Jaime
    Simple Summary Preference tests allow the study of some aspects of the feeding behavior of domestic dogs. However, besides sensorial proprieties of food, intrinsic characteristics of dogs may play a role in diet selection. The aim of this study was to describe the feeding behavior of dogs in relation to diet composition and their intrinsic variables (age, breed, sex, and body weight) by using a ten-year database of two-feeder food preference tests (2007-2017). The content of less digestible fractions like crude fiber and dry matter negatively affected dogs' food preferences. In addition, animals' weight and breed influenced dogs' intake of the most preferred diets, where heaviest dogs presented lower intakes as did the Beagle breed in relation with both Boxer and Labrador Retrievers. Moreover, the hot season of the year decreased dogs' intake of preferred diets. In terms of preferences, Boxers presented a lower preference for selected diets compared to the other breeds. Finally, age and sex did not affect dogs' preference or intake of the foods selected. The understanding of the relationships between food composition and intrinsic variables of dogs with their diet selection could improve specific pet food formulation in order to satisfy animals' physiological and hedonic needs.
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    The Effect of Demonstrator Social Rank on the Attentiveness and Motivation of Pigs to Positively Interact with Their Human Caretakers
    (MDPI, 2021) Luna, Daniela; Gonzalez, Catalina; Byrd, Christopher J.; Palomo, Rocio; Huenul, Elizabeth; Figueroa, Jaime
    Simple Summary Motivation to express a socially learned behavior can be inhibited or facilitated by the presence of socially dominant individuals, who often attract greater attention from their conspecifics. This study investigated whether experienced pigs (termed "demonstrators") of higher rank attract greater attention from their pen mates when they are observed from behind an acrylic panel while being gently handled by the stockperson. We also investigated whether the presence of a demonstrator pig of different social rank, who previously established a positive relationship with the stockperson in presence of conspecifics, affects the motivation and behaviors of their pen mates to positively interact with humans. Our results show that during the gentle handling of the demonstrator, there was an overall preference for observer pigs to visually attend to the dominant demonstrators more than the low-ranking demonstrators. Furthermore, our study shows that the proximity of a dominant demonstrator pig interfered with the motivation of their pen mates to positively interact with the stockperson, whereas the presence of a subordinate demonstrator facilitated the expression of a greater affinity toward the human, resulting in longer physical contact, and a higher percentage of accepted strokes. These findings reveal that social dynamics and dominance rank have a strong effect on the attentional state and the facilitation and inhibition of social behaviors in domestic pigs. In this study, we addressed the social attentiveness, as well as the phenomenon of social facilitation and inhibition in the context of a positive human-pig relationship. Specifically, we investigated whether the social rank of an experienced pig (termed "demonstrator") has an effect on the attentiveness of the remaining pen mates (N = 40) when they observe the demonstrator being gently handled by a stockperson from behind an acrylic panel. We found that pigs preferentially attended to dominant demonstrators rather than subordinate demonstrators during their gentle handling sessions with the stockperson. Additionally, we also examined whether the presence of a demonstrator pig of different social rank, who previously established a positive relationship with the stockperson in presence of conspecifics, affects the behavior and motivation of their pen mates to positively interact with the stockperson. To test for the effect of the presence and demonstrator's social rank on pen mate interactions with the stockperson, we evaluated the behavior of domestic pigs (N = 65) toward the stockperson using a human-approach test in their home-pen. Pigs showed a decrease in their motivation to positively interact with the stockperson when a socially dominant demonstrator was present, behaving similarly to animals receiving minimal human contact (control group). Overall, they exhibited a greater latency to physical contact, a lower acceptance of stroking, and spent more time looking at the stockperson compared to pigs exposed to subordinate demonstrators. Taken together, these findings expand our current understanding of pigs' cognition and social behavior, and the nature of social attention bias in farm animals. Our findings indicate that positive handling of previously selected subordinate demonstrators seems to be the best strategy to reduce the level of fear in large groups of pigs.