RESUMEN

A breast support conveyor has the potential to improve bird welfare by avoiding the need to invert and suspend broilers by their legs as they move from the point of shackling to entry into the electric waterbath. To evaluate its effect on welfare under commercial conditions, a breast support conveyor was installed under the conventional shackle line of a small poultry processing plant. A structured assessment of the behaviour of the birds indicated a significant decrease in struggling and wing flapping at the point of shackling, on the straight conveyor and at entry into the waterbath. This resulted in a lower prevalence of red wing tips and bruising in the first wing joint. The shackle line and conveyor in this installation, however, passed around a 90° corner, which appeared to cause more disturbance to the birds on the conveyor than to comparable birds suspended from shackles in the traditional manner. The results indicate that a breast support conveyor has the potential to improve bird welfare on straight shackle lines and that, because struggling activity and duration following shackling are reduced, the time between shackling and stunning could also be reduced using this method, further improving bird welfare. Breast support conveyors should not be used when the shackle lines have sharp bends.

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RESUMEN

Live weight, subjective scores of condition and conformation, live animal video image analysis (LVIA), ultrasound and X-ray computed tomography (CT) scanning were used to investigate the best method or combination of methods for predicting carcass and meat quality traits in live Texel and Scottish Blackface lambs. Predictors derived from CT alone accounted for a high proportion of the variance in dissected fat and muscle weight in Texel lambs (adjusted R(2)=∼0.8), as well as intra-muscular fat content in the loin (∼0.6), but lower proportions in Blackface lambs (∼0.7 for fat, 0.4-0.5 for muscle and intra-muscular fat), after adjusting for sire and fixed effects. Adding traits measured by other in vivo methods increased prediction accuracies (adjusted R(2)) by up to 0.26, depending on trait and data set. Shear force and ultimate pH could not be accurately predicted using the traits considered here (adjusted R(2)<0.4). Although the same methods tended to be best for predicting product quality traits between breeds, prediction accuracies differed.

RESUMEN

The performance of a visual image analysis (VIA) system was tested with regards to its potential to determine in vivo carcass composition and conformation, either alone, or in conjunction with other in vivo measures such as live weight and backfat depth. Pigs of both sexes of a commercial type were reared and slaughtered at weights ranging from 50 to 120 kg. Feeding was ad libitum on diets ranging from 0.14 to 0.19 kgkg(-1) crude protein content to produce animals of a range of body condition. Two analyses were carried out: the first analysis addressed the relationship between dimensionless carcass and VIA indices; the second analysis assessed the relationship between carcass composition and VIA body shape using detrended carcass and VIA data, which were produced by removal of allometric growth trends. A statistically significant relationship (P<0.05) between in vivo VIA body size and shape and carcass muscle dimensions and composition was found for most body regions. Adjusted R(2) statistics ranged between 0.13 and 0.54 for relative fat weights and between 0.14 and 0.51 for relative lean weights. The predictive power of the regression models, indicated by R(2)-like statistics for prediction, was approximately 70% of the adjusted R(2) values. The descriptive and predictive powers of the corresponding models generally strengthened if VIA indices were combined with other in vivo measurements. The relationships between in vivo and carcass measures remained statistically significant (P<0.05) after removal of the growth trends, although adjusted R(2) statistics generally decreased. The predictive power of models corresponding to the detrended measures was, however, weak. The results show in vivo VIA measurements to be useful in the estimation of muscle size, carcass conformation and composition, all of which are of significant importance to the pig production, marketing and processing industries.

RESUMEN

The growth of carcass tissues and developmental changes in tissue distribution were studied in three pig types which were selected to have morphologies that could be described as attenuated, blocky and flabby. These were achieved by incorporating, respectively, Landrace, Pietrain and Meishan genes to give commercial 'types' (designated L, P and M,) exhibiting some of the phenotypic qualities of these breeds. Twenty-five female pigs of each type with an average start weight of 27.2 kg were fed ad libitum and slaughtered over a (nominal) live weight range of 35-115 kg. Relations were quantified using the logarithmic transformation of data in the allometric model. Significant type differences in relative growth rates (the b coefficient or slope in the logarithmic plot) were not common, occurring in 14% of the relationships examined, whereas 61% of differences in the constant term (a or intercept in the logarithmic plot) were significant. Increase in carcass weight with age was not different between the types but in relation to slaughter live weight (dressing percentage) P had the highest value, M the lowest. Carcass dimensions showed that, relative to body length, P had the widest ham and shoulder over the whole size range whereas M had a deep (ventral-dorsal) shoulder and wide belly, attributes of shape that would be regarded as undesirable by the meat trade. Relative to carcass weight, L was only slightly longer (3 mm) in the body than M at the heavy end of the weight range but markedly longer (29 mm) than P. These differences in carcass conformation were also evident in the shape of pelvic limb muscles which, at a given length, were lightest and narrowest in M and, in some cases, heavier and wider in P than in L. Pelvic limb volume relative to limb length was greatest in P and least in M. Carcass composition (at a given prepared side weight) of P was characterized by low fat and high lean weights, and a high lean to bone ratio. Subcutaneous fat b was lowest in P, indicating that P was early maturing, but M carcasses had the most subcutaneous and intermuscular fat, also indicative of early maturing. There was, thus, no simple relation between maturity characteristics and carcass composition. M carcasses also had the greatest weight of skin. P had a light hindloin and heavy pelvic limb, M a heavy shoulder, hindloin and flank but a light pelvic limb; L had a light shoulder but a heavy foreloin. The distribution of individual tissues mirrored these differences in joint weights to a varying extent; in most cases the match (relatively heavy/light) was with a single tissue. These data, thus, indicated some pig type differences in tissue distribution and of particular significance was the relatively light lean mass in the pelvic limb of M. The results showed important differences in carcass quality between commercially available pig types differing in conformation.

RESUMEN

Social recognition is essential for the maintenance of a stable group structure. Failure to recognise familiar conspecifics in social groups of juvenile pigs may initiate agonistic encounters that can compromise welfare and productivity. Current housing systems may allow build up of atmospheric ammonia that might, in turn, interfere with the olfactory system and compromise olfactory perception. In the present study, 16 juvenile pigs were housed in fresh air while another 16 pigs were kept in an ammoniated atmosphere (approximately 36ppm) for 1 week prior to test and another week during testing. We then assessed the role of olfaction in social recognition and determined whether chronic exposure to ammonia compromised discrimination based on olfactory perception by comparing the pigs' responses to selected cues from a familiar and an unfamiliar pig presented simultaneously in separate chambers of a modified Y-maze in each of two test situations (near, remote). Visual, auditory, olfactory, and tactile cues were all provided in the "near" test situation; here, the stimulus pigs were presented in two separate chambers behind clear perspex walls containing an aperture that allowed nose-to-nose contact between the test and stimulus pigs. On the other hand, the "remote" test provided only olfactory cues via air passed from the chambers containing the stimulus pigs into the test chamber. Each test lasted 5min and the pigs' behaviour was recorded via overhead video cameras; we then measured the accumulated times spent near and the numbers of visits made to the familiar and the unfamiliar stimulus pigs as well as the transitions between them. Overall, pigs made more visits to and spent significantly longer near both the stimulus pigs in the near test than in the remote one (ANOVA, P<0.001). They also made more transitions between the stimuli in the former test than the latter (P<0.001). Pigs from both the ammonia and the fresh-air treatment groups showed social discrimination. However, pigs that had received chronic exposure to ammonia visited the familiar pig more often and spent longer near it than the unfamiliar one regardless of the test situation (P<0.05) whereas those reared in fresh air spent longer near the unfamiliar animal (P<0.05). The present results suggest that pigs from both treatment groups employed olfactory cues in social recognition, but that chronic exposure to ammonia did not interfere with this ability. However, ammonia treatment seemingly affected social preferences, thus indicating an unknown and more fundamental effect of living in ammoniated atmospheres.