Baixe Poultry Meat Science - f VI poster abstracts e outras Notas de estudo em PDF para zootecnia, somente na Docsity! 419 © CAB International 1999. Poultry Meat Science (eds R.I. Richardson and G.C. Mead) POSTER ABSTRACT Effect of broiler housing system on feeding and drinking behaviour P.D. Fortomaris, A.S. Tserveni-Gousi and A.L. Yannakopoulos Department of Animal Production, Veterinary School, Aristotle University, 54006 Thessaloniki, Greece It is well known that designers of poultry facilities can benefit from a knowledge of poultry behaviour. Feeding and drinking behaviour of poultry, mostly physiological behaviour activities, may be modified by the housing system. Sykes (1983) observed that broilers may be considered to be more ‘nibbler’ than ‘meal-eaters’. To analyse the behavioural changes we compared the feeding and drinking behaviour of broilers housed in different systems. The frequency and duration of water and feed consumption was observed in Cobb broilers housed in cages and deep litter in stocking densities of 370 and 665 cm2 per bird, respectively. Feeding and drinking space were similar between the two housing systems. The birds were observed visually at 28, 35 and 42 days of age, using the Focal Animal Sampling and All Occurrences methods (Lehner, 1992). Eight birds were observed for 30 min each per system. Identification was made by using different colours and care was taken to eliminate the disturbance of birds by the presence of the observers. The results (Table 1) show that the housing system affected the duration and frequency of their feeding and drinking activities. Broilers in cages performed 49.3% and 60.7% less feeding and drinking activities compared to broilers on the floor. The feeding and drinking frequency was also less in caged broilers than those on the floor (26.3% and 33.8%, respectively). The results support the conclusion that drinking activities are generally associated with feeding ones and that they are affected by the housing system. Table 1. Effect of housing system on feeding and drinking behaviour of broilers (mean values/system). Feeding Drinking Duration Duration System (min) Frequency (min) Frequency Cages 0.77 1.33 4.62 1.92 Floor 1.96 2.01 9.11 2.59 420 Poster abstracts REFERENCES Lehner, P.N. (1992) Sampling methods in behaviour research. Poultry Science 71, 643—649. Sykes, A.H. (1983) Food intake and its control. In: Physiology and Biochemistry of the Domestic Fowl, Vol.4, Academic Press, London, pp. 1—27. Poster abstracts 423 POSTER ABSTRACT Effect of current frequency during water bath stunning on physical recovery and on the kinetic of bleed out in turkey M. Mouchoniere1, V. Sante1, G. Le Pottier1 and X. Fernandez2 1CIDEF, 11, rue Plaisance, 35310 Mordelles, France; 2INRA - Meat Research Centre, Theix, F-63122 Saint-Genes Champanelle, France Two experiments were carried out to evaluate the influence of the frequency of an AC constant current (150 mA) stunning (4 s) on the physical recovery of turkey hens and toms and on the rate and extent of blood loss. Physical recovery of 70 hens and 78 toms was estimated after stunning at one of five different frequencies. The incidence of cardiac arrest after stunning at 50, 300, 480, 550 and 600 Hz was respectively 100, 60, 30, 30 and 0%, in hens and 53, 38, 0, 0 and 0%, in toms. In hens, time to return of corneal reflex and neck tension and the onset of wing flapping decreased as frequency increased from 300 to 600 Hz: from 19.0 to 6.7 s, 112.7 to 61.5 s and 10.2 s to 7.0 s, respectively. Contrary to hens, about half the toms stunned at 50 Hz did not show cardiac arrest. In these animals, recovery was significantly longer than at the four other frequencies. A total of 50 hens and 53 toms were bled out by severing one carotid artery 10 s after stunning at one of four different frequencies (50, 300, 480 and 600 Hz). The rate and extent of blood loss within 3 min was evaluated. Within the first 20 s, the extent of blood loss, relative to liveweight, increased as stunning frequency increased: from 1.1 to 1.9% in hens and from 1.2 to 1.8% in toms. At 480 and 600 Hz, the maximum blood loss was obtained after 100 s in hens and 140 s in toms, whereas at 50 and 300 Hz, it increased up to 180 s. Large differences in the rate and extent of blood loss were observed within turkeys stunned at 50 or 300 Hz, according to the occurrence of cardiac arrest; cardiac activity was associated with significantly higher rate and extent of blood loss in both sexes. Overall, the work suggests that the duration of unconsciousness decreases as stunning frequency increases. Additional neurophysiological experiments recording EEG and evoked potentials are currently being carried out to confirm these results. 424 Poster abstracts POSTER ABSTRACT Surface heating patterns after microwave decontamination of chicken carcasses E. Göksoy and C. James Food Refrigeration and Process Engineering Research Centre, University of Bristol, Langford, Bristol BS40 5DU, UK Bacteria are predominantly found on the surface of a poultry carcass. Studies have shown that rapid surface heating has the potential to decontaminate without surface cooking. Three published studies have claimed that microwave heating can successfully reduce the bacterial load on chicken carcasses and pieces without cooking, but these studies did not address the problems of reproducibility and uneven heating (‘hot and cold spots’) reported by many other studies. Such uneven heating would make adequate decontamination without cooking difficult. Experiments were carried out to measure the rate and pattern of heating of poultry carcasses in a microwave oven by infrared non-contact thermometry. Overwrapped, chilled (5 ± 1°C) whole chicken carcasses, ca. 2 kg, were heated for 3 min at full power in a domestic microwave oven (Sharp Inverter 1000). After heating, thermal image photographs were taken from different positions using an Agema IR camera in order to determine the final surface temperature pattern over the whole of the carcass. The results show large temperature differences between different areas of the surface of the carcass. The temperature of the surface of wings, the legs and the vent area reached 95°C after 3 min heating. However, the upper back area only reached 25°C and breast area 50—60°C. Accepting that there is no athermal effect on bacteria, these results contest the claims of previous studies, since in order to avoid cooking any areas, other surfaces are prevented from attaining temperatures capable of destroying bacteria. Further unpublished experiments have shown no evidence of any athermal antimicrobial action of microwaves. Given these findings, microwaves are unlikely to be successfully used to decontaminate whole chicken carcasses. Poster abstracts 425 POSTER ABSTRACT The effect of short heating times at high temperatures on the surface appearance of chicken flesh and skin E. Göksoy and C. James Food Refrigeration and Process Engineering Research Centre, University of Bristol, Langford, Bristol BS40 5DU, UK The main drawback to heat-based (hot water or steam) methods of poultry decontamination is that they can cause partial cooking, i.e. denaturation of the muscle proteins. However, since more heat is required to denature protein than to destroy bacterial cells, carefully controlled rapid heating and cooling has the potential to destroy bacteria without surface cooking. The design of such systems requires information on the rate of bacterial death and the rate of change of surface appearance with temperature. Although data are available on the death kinetics of pathogenic bacteria, there are few on the relationship between surface temperature and the appearance of poultry tissues. A controlled series of experiments was carried out using instrumental colour measurements and photographic methods to investigate the relationship between meat surface temperature and appearance changes. Small samples of skin-on chicken breast were vacuum packed and dipped into a hot water bath at a range of temperatures (100, 90, 80, 70, 60 and 50 ± 1°C). After immersion for a set period of time, samples were immediately cooled in a water bath running at 5 ± 1°C. Final appearance was assessed visually, and instrumentally using a Minolta Chroma Meter. Preliminary results show that poultry tissues can be immersed in water at temperatures of 100, 90, 80, 70, 60 and 50 ± 1°C for 1, 2, 6, 9, 60 and 120 s, respectively, without causing irreversible appearance changes. Temperatures of 45 and 30°C caused no significant appearance changes, irrespective of how long the poultry tissues were treated. Noticeable changes were found between the time/temperature relationship for skin and those for exposed muscle. At temperatures of 70°C and above, changes occurred to the skin before the muscle. At lower temperatures initial changes were apparent in both the muscle and skin. Preliminary colour measurements show that instrumentally it is difficult to pick up the slight changes in appearance that cause samples to be deemed unacceptable through visual assessment. Changes in the lightness (L) values of muscle appear the most useful. However, since changes at temperatures 428 Poster abstracts POSTER ABSTRACT Natural antioxidants in feed: effects on quality and storage stability of poultry meats C. Jensen, L. Skibsted and G. Bertelsen Department of Dairy and Food, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark Oxidative changes are the major non-microbial cause of deterioration of meats, as products of autoxidation of unsaturated fatty acids affect wholesomeness and nutritive values. Heat-treated meat products are especially susceptible to lipid oxidation, resulting in a rapidly developing off-flavour denoted warmed-over flavour (WOF), caused by oxidation of the membrane phospholipids. Membrane lipids are protected against oxidation by a number of naturally occurring antioxidants. A strategy to improve the quality of precooked poultry meat products is to supplement antioxidants in the feed to increase the tissue level and increase the oxidative stability of poultry meat and meat products. A number of chicken feeding experiments were conducted using different combinations of antioxidants. A number of products were made and stability measured during storage. These and several other studies have shown that elevated dietary α-tocopherol levels in feed increase tissue concentration, resulting in increased oxidative stability of poultry meats. The level of α-tocopherol in the tissue, however, also depends on the quality of the lipid fractions of the feed. A diet containing oxidized oil, compared to a diet containing fresh oil, results in a lower concentration of α-tocopherol in the tissue, as a result of oxidation of the natural content of α-tocopherol in the oil of the feed. Supplementation with ascorbic acid does not seem to have an effect on the oxidative stability of either raw poultry meat or cooked meat. Supplementation with carotenoids has in some studies been found to increase the oxidative stability of meats. However, in our experiments a higher level of retinol, β-carotene or canthaxanthin in the feed did not affect the oxidative stability of the meats. The latter is expected to be a result of sufficient levels of α-tocopherol in the diets. Thus, supplementation with α-tocopherol is a simple approach to ensure optimum storage stability of poultry meats. Poster abstracts 429 POSTER ABSTRACT Sensory descriptive profiles of deboned poultry classified by shear values of two devices B.G. Lyon and C.E. Lyon USDA, Agricultural Research Service, Richard B. Russell Agricultural Research Centre, P.O. Box 5677, Athens, Georgia 30604-5677, USA Innovative techniques, such as pulsed electric stimulation, wing restraints or tensioning, postchill flattening or extended holding of the deboned breasts and various combinations, have been devised to minimize post-mortem ageing. However, texture (tenderness) of the meat may be compromised. Processors need reliable, rapid and economical ways to measure texture to determine efficacy of new processing techniques. Instrumental devices, such as the Warner-Bratzler and the Allo-Kramer, measure force to shear of muscle fibres and these correlate statistically with sensory texture. However, correlations often oversimplify texture measurements. Instruments do not consider juiciness, other moisture-related characteristics or changes in meat as it is chewed. Previous studies in our laboratory reported shear values from four devices that correlated with consumer sensory tenderness (‘very tough’ to ‘very tender’) for broiler breast meat. These shear value ‘benchmarks’ allowed commercial processors to attach a meaning of relative tenderness to instrumental shear values of cooked breast meat. The objective of this study was to determine the sensory descriptive texture profiles of cooked chicken breast fillets according to their deboning treatment (2, 6, and 24 h post-mortem) and consumer tenderness classification based on shear values from two commonly used devices (Warner-Bratzler and Allo-Kramer blades). Trained descriptive sensory panels identified and quantified specific texture attributes. Sensory texture attributes were separated by variable cluster analysis into five groups representing mechanical, moisture and chewdown characteristics. Warner-Bratzler and Allo-Kramer shear values indicated differences due to deboning time and correlated highly (r ≥ 0.90) with mechanical and chew- down sensory characteristics. However, texture profiles of samples in shear value ranges corresponding to consumer ‘tender—tough’ categories showed that texture remained differentiated by deboning times. Particle size, bolus and wetness characteristics interacted with minor attributes of saliva, ease of swallow and mouth coating to contribute to sensory perceptions and differentiation of texture.