Biomedical subjects

N R Lambe

Publications and source records attributed to N R Lambe.

6 recordsLinked to original sources

PubMed2006

In vivo prediction of internal fat weight in Scottish Blackface lambs, using computer tomography.

From a calibration trial involving computer tomography (CT) scanning and dissection of 45 lambs, a prediction equation was derived to estimate total internal fat weight in Scottish Blackface lambs from measurements taken on cross-sectional CT images. Using data from two cross-sectional images (at the hip and loin) internal fat can be predicted with relatively high accuracy (adjusted R(2) = 62.2%, r = 0.79). The derived equation was then used to predict internal fat weights in a further 427 Scottish Blackface lambs from a separate trial. Phenotypic correlations were calculated between predicted internal fat weight and weights of total carcass fat, muscle and bone, predicted using previously derived equations. When considering absolute tissue weights, adjusted for fixed effects, internal fat showed the strongest positive correlation with carcass fat (0.58), followed by muscle (0.36), and then by bone (0.32). When tissue weights were adjusted for fixed effects and total carcass weight (so considering tissue weights relative to size), internal fat showed a lower correlation with carcass fat weight (0.36) and negative correlations with muscle (-0.35) and bone (-0.19). These results provide the basis for more complex studies of relationships (phenotypic and genetic) between internal fat in hill lambs and economically important traits, such as carcass composition and survival of lambs, and tissue levels in different depots in hill ewes.

Adipose Tissue↗

PubMed2006

A genetic investigation of various growth models to describe growth of lambs of two contrasting breeds.

This study compared the use of various models to describe growth in lambs of 2 contrasting breeds from birth to slaughter. Live BW records (n = 7559) from 240 Texel and 231 Scottish Blackface (SBF) lambs weighed at 2-wk intervals were modeled. Biologically relevant variables were estimated for each lamb from modified versions of the logistic, Gompertz, Richards, and exponential models, and from linear regression. In both breeds, all nonlinear models fitted the data well, with an average coefficient of determination (R2) of > 0.98. The linear model had a lower average R2 than any of the nonlinear models (< 0.94). The variables used to describe the best 3 models (logistic, Gompertz, and Richards) included estimated final BW (A); maximum ADG (B); age at maximum ADG (C); position of point of inflection in relation to A (D, for Richards only). The Richards and Gompertz models provided the best fit (average R2 = 0.986 to 0.989) in both breeds. Richards estimated an extra variable, allowing increased flexibility in describing individual growth patterns, but the Akaike's information criteria value (which weighs log-likelihood by number of parameters estimated) was similar to that of the Gompertz model. Variables A, B, C, and D were moderately to highly heritable in Texel lambs (h2 = 0.33 to 0.87), and genetic correlations between variables within-model ranged from -0.80 to 0.89, suggesting some flexibility to change the shape of the growth curve when selecting for different variables. In SBF lambs, only variables from the logistic and Gompertz models had moderate heritabilities (0.17 to 0.56), but with high genetic correlations between variables within each model (< -0.88 or > 0.92). Selection on growth variables seems promising (in Texel more than SBF), but high genetic correlations between variables may restrict the possibilities to change the growth curve shape. A random regression model was also fitted to the data to allow predictions of growth rates at relevant time points. Heritabilities for growth rates differed markedly at various stages of growth and between the 2 breeds (Texel: 0.14 to 0.74; SBF: 0.07 to 0.34), with negative correlations between growth rate at 60 d of age and growth rate at finishing. Following these results, future studies should investigate genetic relationships between relevant growth curve variables and other important production traits, such as carcass composition and meat quality.

Age Factors↗

PubMed1999

Ability of laying hens to jump between perches: individual variation and the effects of perch separation and motivation on behaviour.

1. This study investigated the ability and the behaviour of laying hens jumping between perches 2 different distances apart using hungry and satiated birds to determine whether behaviour and success were related to motivation. 2. Four groups of 10 birds (Lohmann brown) trained to jump from one perch to another were subjected 4 times to each of the experimental treatments (2 perches with a distance of either 50 or 150 cm between them) whilst either hungry or satiated, controlling for time of day and order of presentation. 3. The behaviour of each bird on the 1st perch was observed for a maximum of 2 min or until the bird jumped from the perch. The outcome of each jump, number of head movements and steps, incidence and duration of calling, and activity score were recorded. 4. The probability of birds jumping was less at the greater distance and was not affected significantly by other experimental factors. 5. Head movements were more frequent in birds which jumped, at the shorter distance, in motivated (hungry) birds and in the morning rather than the afternoon. 6. More stepping was performed by birds which jumped and at the shorter distance; there was no significant effect of motivation or time of day on stepping rate. 7. Birds called more at the greater distance and this was interpreted as indicative of frustration. 8. Subjective scores for activity were lower when perches were separated by the greater distance and when birds were satiated (less motivated) rather than hungry. 9. Agitated head movements and stepping activity thus occurred mainly when birds were motivated and on the point of jumping whereas calling was associated with an apparent inability or unwillingness to jump.

Animals↗

PubMed1998

The fear levels after transport of hens from cages and a free-range system.

All end-of-lay hens must be transported from the production site to the site for slaughter, usually by road. The acts of being crated and transported are likely to be novel and potentially frightening. Frightened birds can be put into tonic immobility (TI), an unlearned, catatonic state, the duration of which is positively related to the fear level of the birds. Ninety ISA Brown free-range birds (in three groups of 30) and 90 caged ISA Brown birds (in similar groups) were transported (one group from cages and free-range per day) on a journey of 68 km (74 min approximately). On their return, each of the birds was subjected to TI. Although no significant differences were recorded between free-range and caged birds after they were transported (P = 0.087), in the comparison between the same birds after 7 wk, without transport, a significant difference in fear levels was observed (P < 0.001). The free-range birds were less frightened than the caged birds. No significant difference was ever found in fear levels for caged birds from different tiers. Handling and transport on this relatively short journey was apparently equally frightening for caged and free-range birds. It cannot be assumed that just because fear levels differ between free-range and caged birds, this difference will be apparent for all novel stimuli. If all birds, at all tiers, receive the same amount of human contact during the production period, there is no reason to expect differences to occur in fear levels of birds from different tiers.

Animal Husbandry↗

PubMed1997

Ability of laying hens to negotiate horizontal perches at different heights, separated by different angles.

1. This paper describes how birds move between horizontal perches at different heights with different angles separating them, using the time to complete the task and the number of birds failing to indicate ability. 2. For the first experiment, 4 groups of 15 birds (ISA Brown) were subjected to each of the experimental treatments (using three perches with angles of 0 degree (horizontal control), 30 degrees, 45 degrees or 60 degrees between them). The birds were required to move upward between the perches for each treatment and then to move downward between the perches, as a second part of the experiment. 3. Birds moving up between the perches took significantly longer at 60 degrees than at any other angle. No birds failed to complete the task. 4. For birds moving downward between the perches, the median time to complete the task increased significantly with angle. Furthermore, the number of birds failing to complete the task increased with angle. 5. A second experiment was conducted to test whether the vertical or horizontal component of distance affected birds' ability to negotiate perches separated by different angles. 6. For the second experiment 4 groups of 10 Lohmann Brown laying hens were subjected to each of the following treatments: two horizontal perches separated by 30 degrees or 60 degrees and either directly, horizontally or vertically separated by a set distance of 50 cm. Birds were required to move both up and down between perches. 7. Birds negotiated horizontally-separated perches more successfully at 30 degrees than at 60 degrees. However, when the vertical distance between the perches was 50 cm there was no significant difference in the ability of birds to move downward at 30 degrees or 60 degrees. For birds moving upward, 60 degrees was easier to negotiate than 30 degrees. 8. The vertical and horizontal separations, as well as the different angles affected the ability of birds to move between perches. There was a general decreasing trend in ability with increasing vertical separation between perches. 9. The findings are important in terms of arrangements of perches to improve bird welfare. To minimise the risk of injury, the angle between perches at different heights should be no more than 45 degrees, and the horizontal and vertical distances between these perches minimised, to allow the birds to be able to move downwards more easily.

Animal Welfare↗

PubMed1996

Working practices in a perchery system, using the OVAKO Working posture Analysing System (OWAS).

Stockworkers should be able to easily manage alternative systems for commercial egg production. Such production systems can be analysed in terms of human welfare, based on ergonomic criteria. Work-related postures can cause discomfort and strain to workers (Stoffert, 1985). The OVAKO Working posture Analysing System (OWAS) developed in 1974 (Karhu et al, 1977) defines body positions during working practices and scores them according to the strain caused. This technique has so far not been used to assist in the design of working systems for the poultry industry. This pilot study was carried out to determine if such a technique could be easily applied to a perchery system and whether it could lead to an improved design. The stockworker was video recorded performing normal duties within the perchery and the positions of the body were assessed, using the OWAS system. It was found that manual collection of floor eggs and reaching into the middle of the perches from the litter side put the most strain on the stockworker. Modification of the perchery, in light of these results, will establish an improved perchery system for the stockworkers.

Journal Article↗