Phenotype alterations can occur naturally during the life span of the domestic fowl. These altera... more Phenotype alterations can occur naturally during the life span of the domestic fowl. These alterations increase the risk to become a target of aggression and may cause a severe impact on the welfare of affected birds. We analysed the behavioural consequences of sequential phenotype alterations and their long-term effects within stable social groups of adult birds differing in group size. Phenotypically homogeneous groups, with 100% or 0% marked individuals, and heterogeneous groups, with 70%, 50% or 30% marked birds, were housed at constant density in groups of 10, 20 or 40. We applied sequential phenotype alterations to homogeneous groups (by marking or unmarking birds) and compared their behavioural response to heterogeneous groups considered controls. Results show that aggression was greatly affected by phenotype alteration but, unexpectedly, group size did not play any relevant role modulating social responses. Aggression was directed towards the first altered birds and was significantly higher than in control groups. Long term effects were detected, as victimized individuals failed to engage in aggression at any time and adapted their behaviour to minimize aggressive encounters (e.g. high perch use). Therefore, we provide evidence of long-lasting submissive strategies in stable groups of adult domestic fowl, highlighting the relevance of phenotype alteration on the social dynamics of affected birds. Phenotype alterations could help explain much of the targeted aggression observed in producing flocks which severely affects animal welfare. Recent advances in the study of the social dynamics of the domestic fowl have shown that individuals that are phenotypically different from their conspecifics, due to a natural or artificial variation in feather colouration, are at a higher risk of receiving aggressive interactions from their flock mates 1,2. The group pressure resulting from these interactions may affect the social, feeding or locomotory behaviours of altered individuals 3,4 as a strategy to avoid interactions with flock-mates. Aggressive interactions in the domestic fowl are typically directed towards subordinates 5 and sometimes linked to specific phenotypes 6. Traditional studies on the social behaviour of the domestic fowl describe initial periods of intense aggression in small flocks until a social hierarchy is established 7 and predict the number of interactions during hierarchy formation to increase with group size 8. For a hierarchical social structure to be stable group members must recognize each other individually 7,9 or through badges of status 6,9,10. Badges of status are traits that signal fighting ability when individual recognition is not an option 11,12 , thus allowing dominant individuals to reduce the cost invested in aggression 13,14. Familiarity based on appearance also plays a role on the ability to recognize group mates individually or based on badges of status, and on the frequency of aggressive interactions displayed 15 , which could also be dependent on group size 16. Experimental studies have shown that phenotype diversity leads to frequency-dependent targeted aggression in young domestic fowl, with more aggression directed towards those individuals showing the less common phenotype in the population 2,4,17. Such studies have attempted to answer fundamental questions about the motivation behind aggressive interactions and considered their practical implications. Modern domestic fowl flocks are highly homogenous due to hybrid genetics (selection for health and performance traits) and management practices designed to accommodate the needs of the birds. Nevertheless, naturally occurring phenotype alterations may emerge repeatedly as a result of disease or injuries and are likely to affect different proportions of individuals within a group. Such alterations are more likely to take place as the flock ages and it is common to observe how individuals diverging from the average flock phenotype are targets for aggression (Estevez, personal observation). Repeated occurrences of social stress over time could induce physiological adaptation
<p>Frequency of total aggression per bird at T0 (27–28 weeks; 1A), T1 (35–36 weeks; 1B), T2... more <p>Frequency of total aggression per bird at T0 (27–28 weeks; 1A), T1 (35–36 weeks; 1B), T2 (39–40 weeks; 1C) and T3 (45–46 weeks, 1D). Bars represent means ± SE. M = marked; U = unmarked. Phenotypic appearance (PA) treatments: originally homogeneous (100U, 100M) and controls (30M/70U, 50M/50U, 70M/30U). Different letters denote significant differences among PA treatments at <i>P</i><0.05.</p
<p>Three different group sizes (GS) were tested (10, 20 and 40) for each original phenotypi... more <p>Three different group sizes (GS) were tested (10, 20 and 40) for each original phenotypic appearance (PA) treatment: 100% U (100U), 30% (30M/70U), 50% (50M/50U), 70% (70M/30U), 100% M (100M)). U: Unmarked, M: Marked. Originally heterogeneous groups: 30, 50 and 70% altered from day one were used as controls. Adapted from Marin et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188931#pone.0188931.ref047" target="_blank">47</a>].</p
<p>M = marked; U = unmarked. Differences between observed and expected aggressive interacti... more <p>M = marked; U = unmarked. Differences between observed and expected aggressive interactions (means ± SE) for each possible interacting pair (MM, MU, UM and UU) and phenotypic appearance (PA) treatment: originally homogeneous (100U, 100M), and controls (30M/70U, 50M/50U, 70M/30U). 3A) T0: 27–28 weeks; 3B) T1: 35–36; 3C) T2:39–40; 3D) T3:45–46. Different letters indicate significant differences among interacting pairs within the same PA treatment.</p
Dataset of aggression among groups of laying hens. Effects of group size and phenotypic appearean... more Dataset of aggression among groups of laying hens. Effects of group size and phenotypic appeareance alterations during adulthood.
Educators need to prepare students for an increasingly complex andinterconnected world, and tradi... more Educators need to prepare students for an increasingly complex andinterconnected world, and traditional teaching methods can fail to help students develop some of the needed skills. We set up to combine flippedcalssroom strategies and mapping techniques with the aim to encourage creativity and adaptability while ensuring deep learning of complex theoretical concepts. A simple analogical disruption was added, in the shape of post-it notes used to build concept maps, to disturb an otherwise heavy technologybased course. Our teachinginnovation has been pilot tested in a range of groups and theoretical concepts with preliminary positive feedback being reported by students. They have described the innovation as “an entertaining change”, but also referring to improvements on their information searching and critical thinking skills. Students also found that the analogical mapping activity through post-it notes encouraged participation and an active attitude in class. Overall, they reported...
Domestic fowl in small groups are assumed to establish hierarchical systems based on individual r... more Domestic fowl in small groups are assumed to establish hierarchical systems based on individual recognition. Conversely, interactions in large groups are modulated by badges of status. Previous studies suggested that birds differing in phenotypic appearance (PA) became targets for aggression, possibly mistaking altered PA for badges of status. We evaluated the impact of altering PA on 0, 30, 50, 70 or 100% of the birds' house at three experimental group sizes (GS). Tested GS were 10, 20 or 40 (8 birds/m 2 , 3 pens/GSxPA, 45 total). Thus, for each GS we had groups initially homogenous (100U, U = Unmarked; 100M, M = Marked), or heterogeneous M and U phenotypes coexisting in different proportions: 30M/ 70U, 50M/50U, and 70M/30U, remaining unchanged until 33 weeks of age. Then, homogeneous groups (100U and 100M) were sequentially altered by marking or unmarking 30, 50 and 70% of birds at 34, 38 and 44 weeks, respectively. Aggressive interactions were observed before applying changes at 27-28 weeks (T0), and after each sequential PA change on week 35-36 (T1), 39-40 (T2) and 45-46 (T3). Frequency of aggressive interactions in altered groups at T1, T2, and T3 were compared with non-altered heterogeneous controls. Results indicate no differences across initial PA and GS treatments (T0; P>0.05). However, aggression escalation was observed at T1 immediately after the first PA manipulation (Tukey P<0.05 altered vs controls). Aggression in altered groups remained high at T2 when compared to controls (Tukey, P<0.05), although by T3 interactions declined to almost initial levels (Tukey, P>0.05 altered vs controls). Aggressive interactions at T1 and T2 were predominantly directed from unaltered towards recently altered birds, irrespectively of their initial phenotype and of the GS. These results demonstrate that a sudden change in PA affects group dynamics. Altered birds were exposed to escalated aggression even in small groups, where individual recognition was presumed.
Non-caged production systems offer greater freedom of movement and behavioural opportunities to p... more Non-caged production systems offer greater freedom of movement and behavioural opportunities to pullets, which may also include the occurrence of undesired behaviours. The incidence of such behaviours may be affected by group size but also by the group membersí phenotype. This study was designed to explore the effects of group size and phenotypic appearance in the social dynamics of pullets. A total of 1050 day old Hy-line Brown was randomly assigned to 45 pens at 3 group sizes (GS), 10, 20 and 40 birds (constant density 8 hens/m 2). For all GS treatments, the phenotypic appearance (PA) of different bird proportions was modified with a black mark at the back of their head. Two types of populations were studied: homogenous (0, 100%) with all pen members presenting the same marked (M) or unmarked (U) phenotype, and heterogeneous (30, 50, and 70%) were the two phenotypes (M and U) coexisted in the same pen. All pens were observed during rearing on alternate weeks. Aggressive and affiliative social interactions performed among group members were registered together with their PA (M or U). The observed and expected mean frequencies for all phenotype combinations involved in the social interaction were calculated: MM, MU, UU and UM, where the giverís phenotype is indicated by the first letter and the receiverís phenotype by the second letter. Data were analysed with mixed model ANOVAs that included GS and PA as fixed factors for the general model, and GS, PA and type of interaction (MM, MU, UU, UM) to determine the direction of the interaction in the case of heterogeneous groups. Both aggressive (threats) and affiliative interactions (exploratory pecking and beak pecking) were more frequent in small (10) than in large (20, 40) GS (P < 0.05) regardless of PA (PA, P > 0.05; GS × PA, P > 0.05). Aggressive interactions however, occurred at a higher than expected frequency in heterogeneous GS 20, and were predominantly from U towards M birds (UM; P < 0.05), as compared to MU or UU. The significant interaction among GS × PA × Type of interaction for affiliative behaviours did not show a clear relationship. Overall, the results obtained showed that both aggressive and affiliative interactions occurred at a higher frequency in the smallest GS 10. Although the effects of PA were not as clear as expected, these results provide evidence of the directionality of the aggressive interactions from U towards M birds especially at intermediate GS 20.
Lamb rearing is a key point to ensure good quality at the end of the production cycle. Fostering ... more Lamb rearing is a key point to ensure good quality at the end of the production cycle. Fostering and artificial rearing are techniques commonly used when natural rearing is compromised. However, there is a lack of research investigating their impact on the product´s quality, especially when lambs are slaughtered late, around 6 months of age. The current study investigated the effects of artificially reared and fostered lambs on growth, carcass and meat quality. The three foster methods under study were birth fluids, cervical stimulation combined with birth fluids and restraint. Animals were weaned at 3 months of age, and processed at 6 months of age. Artificially reared lambs presented lower weight gains than ewe reared ones at young ages. They also presented worse conformation scores at the processing plant. No differences could be found for growth rates, carcass or meat quality among the foster methods tested.
The objective of this study was to determine if short (1 h) or long (24 h) lairage at the abattoi... more The objective of this study was to determine if short (1 h) or long (24 h) lairage at the abattoir has an effect on instrumental meat quality (ultimate meat pH, water holding capacity, colour, raw and cooked texture) and sensory meat quality (trained sensory panel) of commercial lambs. This was part of a combined study where assessment of animal welfare (haematological and physiological parameters) showed that lairage time had a significant effect (p<0.05) on stress indicators, but not on meat quality traits. Meat quality parameters were generally lower after short (1 h) than after long (24 h) lairage. There were no significant differences found on instrumental and sensorial meat quality with the exception of yellowness and hue (p<0.05) within colour analysis. Trained sensory panellists were unable to identify a significant difference between variables. This suggests that although lairage may affect the product in subtle ways it does not affect meat quality significantly enoug...
Alterations of birds&amp;#39; phenotypic appearance (PA) may lead to unwanted behaviors, pote... more Alterations of birds&amp;#39; phenotypic appearance (PA) may lead to unwanted behaviors, potentially impairing poultry welfare, health, and productive performance. Likewise, group size may play an important role modulating the expression of adaptive behaviors. This study evaluates whether changes in the PA of Hy-line Brown laying hens may affect their BW and egg production, and if so, whether these effects depend on group size. A total of 1,050 one-day-old chicks were randomly assigned to 1 of 45 pens. Groups were of 10, 20, or 40 individuals (8 hens/m(2)). At arrival, the PA of 0, 30, 50, 70, or 100% of the birds within each group was artificially altered by marking the back of their heads black. The remaining birds within groups were unaltered. The 30% marked hens within groups of 10 individuals had a lower BW at 24 wk of age than their 70% unmarked counterparts, whereas the other groups showed similar BW. No differences were detected in egg laying performance during this phase. Next, within the initially homogeneous groups (0 and 100%), 30, 50, and 70% of the hens were either marked or unmarked (PA changed) sequentially at 34, 38, and 44 wk of age. Hens within the initially heterogeneous groups of 30, 50, and 70% marked birds remained unchanged and were used as controls. Groups of 40 individuals showed a reduction in BW gain and weekly hen-day-egg production after 30% PA changes, as compared with control counterparts. No differences were found in pens of 10 hens, and the groups of 20 showed intermediate results. A transient reduction in egg production was found after 50% PA changes. No further productive effects were observed after 70% changes. Our findings suggest that differences in hen appearance, which may occur due to variations in health status, injuries, and other natural causes, can be critical for production and welfare management practices depending both on the flock size and the birds&amp;#39; previous experience in exposure to group phenotypic heterogeneity.
The study analysed the effect of lairage on some indicators of welfare and meat quality in lambs.... more The study analysed the effect of lairage on some indicators of welfare and meat quality in lambs. Forty-eight lambs were divided into two treatments: T1 without lairage and T2 with 12 h of lairage. Blood samples were collected at slaughter to analyse cortisol, lactate, glucose, creatinine kinase, non-esterified fatty acid, white blood cells, red blood cells, haematocrit and ratio of neutrophil : lymphocytes. Meat from the M. longissimus was analysed in terms of pH 24 h post-mortem, water-holding capacity, texture and colour. Sensory analyses were performed by a trained panel. Lairage had a significant effect on stress response, but had no effect on haematological variables. The lambs with a lairage period before slaughter (T2) had significantly (P ≤ 0.001) lower values of cortisol at the time of slaughter. A similar result was observed for lactate and glucose, with T1 lambs showing significantly (P ≤ 0.05) higher values than T2 lambs. The creatinine kinase activity and non-esterifie...
Phenotype alterations can occur naturally during the life span of the domestic fowl. These altera... more Phenotype alterations can occur naturally during the life span of the domestic fowl. These alterations increase the risk to become a target of aggression and may cause a severe impact on the welfare of affected birds. We analysed the behavioural consequences of sequential phenotype alterations and their long-term effects within stable social groups of adult birds differing in group size. Phenotypically homogeneous groups, with 100% or 0% marked individuals, and heterogeneous groups, with 70%, 50% or 30% marked birds, were housed at constant density in groups of 10, 20 or 40. We applied sequential phenotype alterations to homogeneous groups (by marking or unmarking birds) and compared their behavioural response to heterogeneous groups considered controls. Results show that aggression was greatly affected by phenotype alteration but, unexpectedly, group size did not play any relevant role modulating social responses. Aggression was directed towards the first altered birds and was significantly higher than in control groups. Long term effects were detected, as victimized individuals failed to engage in aggression at any time and adapted their behaviour to minimize aggressive encounters (e.g. high perch use). Therefore, we provide evidence of long-lasting submissive strategies in stable groups of adult domestic fowl, highlighting the relevance of phenotype alteration on the social dynamics of affected birds. Phenotype alterations could help explain much of the targeted aggression observed in producing flocks which severely affects animal welfare. Recent advances in the study of the social dynamics of the domestic fowl have shown that individuals that are phenotypically different from their conspecifics, due to a natural or artificial variation in feather colouration, are at a higher risk of receiving aggressive interactions from their flock mates 1,2. The group pressure resulting from these interactions may affect the social, feeding or locomotory behaviours of altered individuals 3,4 as a strategy to avoid interactions with flock-mates. Aggressive interactions in the domestic fowl are typically directed towards subordinates 5 and sometimes linked to specific phenotypes 6. Traditional studies on the social behaviour of the domestic fowl describe initial periods of intense aggression in small flocks until a social hierarchy is established 7 and predict the number of interactions during hierarchy formation to increase with group size 8. For a hierarchical social structure to be stable group members must recognize each other individually 7,9 or through badges of status 6,9,10. Badges of status are traits that signal fighting ability when individual recognition is not an option 11,12 , thus allowing dominant individuals to reduce the cost invested in aggression 13,14. Familiarity based on appearance also plays a role on the ability to recognize group mates individually or based on badges of status, and on the frequency of aggressive interactions displayed 15 , which could also be dependent on group size 16. Experimental studies have shown that phenotype diversity leads to frequency-dependent targeted aggression in young domestic fowl, with more aggression directed towards those individuals showing the less common phenotype in the population 2,4,17. Such studies have attempted to answer fundamental questions about the motivation behind aggressive interactions and considered their practical implications. Modern domestic fowl flocks are highly homogenous due to hybrid genetics (selection for health and performance traits) and management practices designed to accommodate the needs of the birds. Nevertheless, naturally occurring phenotype alterations may emerge repeatedly as a result of disease or injuries and are likely to affect different proportions of individuals within a group. Such alterations are more likely to take place as the flock ages and it is common to observe how individuals diverging from the average flock phenotype are targets for aggression (Estevez, personal observation). Repeated occurrences of social stress over time could induce physiological adaptation
<p>Frequency of total aggression per bird at T0 (27–28 weeks; 1A), T1 (35–36 weeks; 1B), T2... more <p>Frequency of total aggression per bird at T0 (27–28 weeks; 1A), T1 (35–36 weeks; 1B), T2 (39–40 weeks; 1C) and T3 (45–46 weeks, 1D). Bars represent means ± SE. M = marked; U = unmarked. Phenotypic appearance (PA) treatments: originally homogeneous (100U, 100M) and controls (30M/70U, 50M/50U, 70M/30U). Different letters denote significant differences among PA treatments at <i>P</i><0.05.</p
<p>Three different group sizes (GS) were tested (10, 20 and 40) for each original phenotypi... more <p>Three different group sizes (GS) were tested (10, 20 and 40) for each original phenotypic appearance (PA) treatment: 100% U (100U), 30% (30M/70U), 50% (50M/50U), 70% (70M/30U), 100% M (100M)). U: Unmarked, M: Marked. Originally heterogeneous groups: 30, 50 and 70% altered from day one were used as controls. Adapted from Marin et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0188931#pone.0188931.ref047" target="_blank">47</a>].</p
<p>M = marked; U = unmarked. Differences between observed and expected aggressive interacti... more <p>M = marked; U = unmarked. Differences between observed and expected aggressive interactions (means ± SE) for each possible interacting pair (MM, MU, UM and UU) and phenotypic appearance (PA) treatment: originally homogeneous (100U, 100M), and controls (30M/70U, 50M/50U, 70M/30U). 3A) T0: 27–28 weeks; 3B) T1: 35–36; 3C) T2:39–40; 3D) T3:45–46. Different letters indicate significant differences among interacting pairs within the same PA treatment.</p
Dataset of aggression among groups of laying hens. Effects of group size and phenotypic appearean... more Dataset of aggression among groups of laying hens. Effects of group size and phenotypic appeareance alterations during adulthood.
Educators need to prepare students for an increasingly complex andinterconnected world, and tradi... more Educators need to prepare students for an increasingly complex andinterconnected world, and traditional teaching methods can fail to help students develop some of the needed skills. We set up to combine flippedcalssroom strategies and mapping techniques with the aim to encourage creativity and adaptability while ensuring deep learning of complex theoretical concepts. A simple analogical disruption was added, in the shape of post-it notes used to build concept maps, to disturb an otherwise heavy technologybased course. Our teachinginnovation has been pilot tested in a range of groups and theoretical concepts with preliminary positive feedback being reported by students. They have described the innovation as “an entertaining change”, but also referring to improvements on their information searching and critical thinking skills. Students also found that the analogical mapping activity through post-it notes encouraged participation and an active attitude in class. Overall, they reported...
Domestic fowl in small groups are assumed to establish hierarchical systems based on individual r... more Domestic fowl in small groups are assumed to establish hierarchical systems based on individual recognition. Conversely, interactions in large groups are modulated by badges of status. Previous studies suggested that birds differing in phenotypic appearance (PA) became targets for aggression, possibly mistaking altered PA for badges of status. We evaluated the impact of altering PA on 0, 30, 50, 70 or 100% of the birds' house at three experimental group sizes (GS). Tested GS were 10, 20 or 40 (8 birds/m 2 , 3 pens/GSxPA, 45 total). Thus, for each GS we had groups initially homogenous (100U, U = Unmarked; 100M, M = Marked), or heterogeneous M and U phenotypes coexisting in different proportions: 30M/ 70U, 50M/50U, and 70M/30U, remaining unchanged until 33 weeks of age. Then, homogeneous groups (100U and 100M) were sequentially altered by marking or unmarking 30, 50 and 70% of birds at 34, 38 and 44 weeks, respectively. Aggressive interactions were observed before applying changes at 27-28 weeks (T0), and after each sequential PA change on week 35-36 (T1), 39-40 (T2) and 45-46 (T3). Frequency of aggressive interactions in altered groups at T1, T2, and T3 were compared with non-altered heterogeneous controls. Results indicate no differences across initial PA and GS treatments (T0; P>0.05). However, aggression escalation was observed at T1 immediately after the first PA manipulation (Tukey P<0.05 altered vs controls). Aggression in altered groups remained high at T2 when compared to controls (Tukey, P<0.05), although by T3 interactions declined to almost initial levels (Tukey, P>0.05 altered vs controls). Aggressive interactions at T1 and T2 were predominantly directed from unaltered towards recently altered birds, irrespectively of their initial phenotype and of the GS. These results demonstrate that a sudden change in PA affects group dynamics. Altered birds were exposed to escalated aggression even in small groups, where individual recognition was presumed.
Non-caged production systems offer greater freedom of movement and behavioural opportunities to p... more Non-caged production systems offer greater freedom of movement and behavioural opportunities to pullets, which may also include the occurrence of undesired behaviours. The incidence of such behaviours may be affected by group size but also by the group membersí phenotype. This study was designed to explore the effects of group size and phenotypic appearance in the social dynamics of pullets. A total of 1050 day old Hy-line Brown was randomly assigned to 45 pens at 3 group sizes (GS), 10, 20 and 40 birds (constant density 8 hens/m 2). For all GS treatments, the phenotypic appearance (PA) of different bird proportions was modified with a black mark at the back of their head. Two types of populations were studied: homogenous (0, 100%) with all pen members presenting the same marked (M) or unmarked (U) phenotype, and heterogeneous (30, 50, and 70%) were the two phenotypes (M and U) coexisted in the same pen. All pens were observed during rearing on alternate weeks. Aggressive and affiliative social interactions performed among group members were registered together with their PA (M or U). The observed and expected mean frequencies for all phenotype combinations involved in the social interaction were calculated: MM, MU, UU and UM, where the giverís phenotype is indicated by the first letter and the receiverís phenotype by the second letter. Data were analysed with mixed model ANOVAs that included GS and PA as fixed factors for the general model, and GS, PA and type of interaction (MM, MU, UU, UM) to determine the direction of the interaction in the case of heterogeneous groups. Both aggressive (threats) and affiliative interactions (exploratory pecking and beak pecking) were more frequent in small (10) than in large (20, 40) GS (P < 0.05) regardless of PA (PA, P > 0.05; GS × PA, P > 0.05). Aggressive interactions however, occurred at a higher than expected frequency in heterogeneous GS 20, and were predominantly from U towards M birds (UM; P < 0.05), as compared to MU or UU. The significant interaction among GS × PA × Type of interaction for affiliative behaviours did not show a clear relationship. Overall, the results obtained showed that both aggressive and affiliative interactions occurred at a higher frequency in the smallest GS 10. Although the effects of PA were not as clear as expected, these results provide evidence of the directionality of the aggressive interactions from U towards M birds especially at intermediate GS 20.
Lamb rearing is a key point to ensure good quality at the end of the production cycle. Fostering ... more Lamb rearing is a key point to ensure good quality at the end of the production cycle. Fostering and artificial rearing are techniques commonly used when natural rearing is compromised. However, there is a lack of research investigating their impact on the product´s quality, especially when lambs are slaughtered late, around 6 months of age. The current study investigated the effects of artificially reared and fostered lambs on growth, carcass and meat quality. The three foster methods under study were birth fluids, cervical stimulation combined with birth fluids and restraint. Animals were weaned at 3 months of age, and processed at 6 months of age. Artificially reared lambs presented lower weight gains than ewe reared ones at young ages. They also presented worse conformation scores at the processing plant. No differences could be found for growth rates, carcass or meat quality among the foster methods tested.
The objective of this study was to determine if short (1 h) or long (24 h) lairage at the abattoi... more The objective of this study was to determine if short (1 h) or long (24 h) lairage at the abattoir has an effect on instrumental meat quality (ultimate meat pH, water holding capacity, colour, raw and cooked texture) and sensory meat quality (trained sensory panel) of commercial lambs. This was part of a combined study where assessment of animal welfare (haematological and physiological parameters) showed that lairage time had a significant effect (p<0.05) on stress indicators, but not on meat quality traits. Meat quality parameters were generally lower after short (1 h) than after long (24 h) lairage. There were no significant differences found on instrumental and sensorial meat quality with the exception of yellowness and hue (p<0.05) within colour analysis. Trained sensory panellists were unable to identify a significant difference between variables. This suggests that although lairage may affect the product in subtle ways it does not affect meat quality significantly enoug...
Alterations of birds&amp;#39; phenotypic appearance (PA) may lead to unwanted behaviors, pote... more Alterations of birds&amp;#39; phenotypic appearance (PA) may lead to unwanted behaviors, potentially impairing poultry welfare, health, and productive performance. Likewise, group size may play an important role modulating the expression of adaptive behaviors. This study evaluates whether changes in the PA of Hy-line Brown laying hens may affect their BW and egg production, and if so, whether these effects depend on group size. A total of 1,050 one-day-old chicks were randomly assigned to 1 of 45 pens. Groups were of 10, 20, or 40 individuals (8 hens/m(2)). At arrival, the PA of 0, 30, 50, 70, or 100% of the birds within each group was artificially altered by marking the back of their heads black. The remaining birds within groups were unaltered. The 30% marked hens within groups of 10 individuals had a lower BW at 24 wk of age than their 70% unmarked counterparts, whereas the other groups showed similar BW. No differences were detected in egg laying performance during this phase. Next, within the initially homogeneous groups (0 and 100%), 30, 50, and 70% of the hens were either marked or unmarked (PA changed) sequentially at 34, 38, and 44 wk of age. Hens within the initially heterogeneous groups of 30, 50, and 70% marked birds remained unchanged and were used as controls. Groups of 40 individuals showed a reduction in BW gain and weekly hen-day-egg production after 30% PA changes, as compared with control counterparts. No differences were found in pens of 10 hens, and the groups of 20 showed intermediate results. A transient reduction in egg production was found after 50% PA changes. No further productive effects were observed after 70% changes. Our findings suggest that differences in hen appearance, which may occur due to variations in health status, injuries, and other natural causes, can be critical for production and welfare management practices depending both on the flock size and the birds&amp;#39; previous experience in exposure to group phenotypic heterogeneity.
The study analysed the effect of lairage on some indicators of welfare and meat quality in lambs.... more The study analysed the effect of lairage on some indicators of welfare and meat quality in lambs. Forty-eight lambs were divided into two treatments: T1 without lairage and T2 with 12 h of lairage. Blood samples were collected at slaughter to analyse cortisol, lactate, glucose, creatinine kinase, non-esterified fatty acid, white blood cells, red blood cells, haematocrit and ratio of neutrophil : lymphocytes. Meat from the M. longissimus was analysed in terms of pH 24 h post-mortem, water-holding capacity, texture and colour. Sensory analyses were performed by a trained panel. Lairage had a significant effect on stress response, but had no effect on haematological variables. The lambs with a lairage period before slaughter (T2) had significantly (P ≤ 0.001) lower values of cortisol at the time of slaughter. A similar result was observed for lactate and glucose, with T1 lambs showing significantly (P ≤ 0.05) higher values than T2 lambs. The creatinine kinase activity and non-esterifie...
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