British Poultry Science

Randall, J. M.; Streader, W. V.; Meehan, A. M.

doi: 10.1080/00071669308417622pmid: 8242403

Abstract 1. This research established the magnitudes and frequencies of vibration acceleration on two typical broiler bird transporters, one with leaf and the other with air suspension. 2. Vibration measurements were made using triaxial accelerometers mounted on the chassis and in the bird containers, with vehicles both loaded and unloaded. 3. In the vertical axis the fundamental vehicle frequency is between 1 and 2 Hz with a secondary peak at 10 Hz. 4. In the lateral axis with air suspension, the maximum level of vibration on the chassis occurred at 12 to 18 Hz; this was less evident with leaf suspension. 5. The magnitudes of vibration acceleration occurring in the bird containers would be fairly uncomfortable for the seated human. Frequency weightings and response to different axes and magnitudes of vibration must be established before the response of birds can be predicted.

Geraert, P. A.; Guillaumin, S.; Leclercq, B.

doi: 10.1080/00071669308417623pmid: 8242404

Abstract 1. Genetically lean (LL) or fat (FL) male chickens were exposed to either high (32°C) or control (22°C) ambient temperature up to 9 weeks of age. They were fed on one of two isoenergetic diets differing in protein content: 190 or 230 g/kg. 2. At 22°C, weight gain of LL broilers was the same as in FL chickens, but at the high temperature LL birds grew to a greater weight than FL ones. 3. Food conversion efficiency was not affected by ambient temperature in LL chickens but was depressed in FL ones at 32°C. 4. Increasing dietary protein content did not alleviate heat‐induced growth depression irrespective of the genotype. 5. Gross protein efficiency was higher in LL chickens and was less depressed at 32°C than in FL birds. 6. Fat deposition decreased with increasing protein concentration at normal temperature in both genotypes; at high temperature, high protein content enhanced fatness, particularly in LL chickens. 7. Thus, genetically lean broilers demonstrated a greater resistance to hot conditions: this was indicated by enhanced weight gain and improved food and protein conversion efficiencies.

Sparks, N. H. C.; Burgess, A. D.

doi: 10.1080/00071669308417624pmid: 8242405

Abstract 1. Eggs from a broiler breeder flock were sanitised using a continuous spray sanitising machine. The effect of this treatment on the ability of the cuticle to resist water and bacterial penetration was investigated throughout the production cycle. 2. The volume of water taken up by eggs that had been sanitised was significantly (P < 0.001) greater than that taken up by the control eggs. The volume of water taken up by the sanitised eggs increased as the flock age increased, whereas water uptake was maximal for the control eggs at 42 weeks of age. 3. There was no correlation between water uptake values and shell thickness or egg weight for either the sanitised or control eggs. 4. Sanitised eggs tended to dominate the “poor cuticle quality” category at all flock ages, when a subjective assessment of cuticle quality was made using the stain Edicol Supra Pea Green. 5. Egg sanitising did not affect shell reflectance values, shell thickness or the percentage of cracked shells. 6. When flock age reached 49 weeks of age, the sanitising process significantly (P < 0.001) reduced hatchability.

Dunn, A. A.; Kilpatrick, D. J.; Gault, N. F. S.

doi: 10.1080/00071669308417625pmid: N/A

Abstract 1. An experiment was conducted to quantify the extent of variability in the texture of cooked poultry breast meat and to attempt to identify which intrinsic and extrinsic factors contribute to this. 2. Free range (FR) and standard (STD) broilers were killed and processed under commercial conditions and the M. pectoralis major muscle assessed for ultimate pH (pHu), sarcomere length, cooking loss and texture 24 h and 7 d after slaughter. 3. Although FR broilers were females with an average age of 60 d, whereas the STD broilers were 45 d old and predominantly male, there were no significant differences in mean values obtained for pHu, sarcomere length, cooking loss and shear force results between the two bird types. 4. While aging for 7 d increased the pHu and cooking loss means, sarcomere length means remained unchanged and shear force values decreased by 6% and 9% for FR and STD birds respectively. 5. Variability in shear force values also decreased on aging for 7 d, no birds having values above 4 kg/cm2 on day 7 whereas 16% were above this value on day 1. 6. There were significant correlations between the results for shear force, pHu and sarcomere length, indicating that increased shear force values were associated with a decrease in both pHu and sarcomere length. 7. These correlations suggest that variability in the texture of cooked M. pectoralis major from FR and STD chickens is strongly influenced by those post‐mortem biochemical changes which lead to the development of rigor during the early stages of processing.

Dunn, A. A.; Tolland, E. L. C.; Kilpatrick, D. J.; Gault, N. F. S.

doi: 10.1080/00071669308417626pmid: N/A

Abstract 1. The relationship between isometric tension development and pH, as a function of storage temperature between 0° and 40°C, was examined in chicken M. pectoralis major (PM) muscle during the critical 24 h post‐mortem period. 2. The muscle strips incubated at 0°C developed a peak isometric tension of 53.3 g/cm2. This occurred after only 17 min incubation when the pH was 7.02, demonstrating the potential of chicken PM muscle to cold shorten. Peak isometric tension at 5°C was considerably lower than that generated at 0°C. However, as this occurred when the muscle pH was still high (6.70), this also indicated some potential to cold shorten at 5°C. 3. At 10° to 30°C, the muscle strips developed mean peak isometric tensions of 18 g/cm2 after 6 h incubation by which time the muscle pH had fallen to 6.00, demonstrating a limited potential to rigor shorten. In contrast, those incubated at 40°C developed a peak tension of 54.5 g cm2 after 75 min when the muscle pH was also around 6.00, thus indicating the potential for intensive rigor shortening at this temperature. Incubation temperature and the resultant muscle pH therefore determine the potential of chicken PM muscle to either cold shorten or rigor shorten. 4. Despite the differences found in isometric tension profiles, cooked meat texture after isometric tension measurement was not significantly different at any of the temperatures studied primarily because the muscle strips were essentially prevented from shortening.

Dunn, A. A.; Kilpatrick, D. J.; Gault, N. F. S.

doi: 10.1080/00071669308417627pmid: N/A

Abstract 1. Muscle shortening, sarcomere lengths and pH values were measured in strips of chicken M. pectoralis major (PM) muscle incubated at different time (0 to 24 h) and temperature (0° to 40°C) combinations immediately after slaughter; their effects on cooking loss and meat tenderness determined. 2. Maximum muscle shortening of 39% and 43% occurred at 0°C and 40°C respectively. At 0°C, most shortening occurred within 90 min postmortem when the pH of the muscle ranged from 7.13 to 6.52. In contrast, at 40°C, most shortening occurred during the development of rigor mortis, between 90 and 380 min post‐mortem, when the muscle pH ranged from 6.16 to 5.89. In a similar manner, minimum sarcomere lengths of 1.38 μm were reached after 90 min at 0°C while more severe sarcomere shortening, to 0.96 μm and 0.86 μm at 30°C and 40°C respectively, was not complete until after 380 min post‐mortem. Between 5°C and 20°C, muscle shortening ranged from 25 to 34% while minimum sarcomere lengths of 1.33 μm were recorded. 3. Cooking losses increased on average from 7 to 16% between 30 and 380 min post‐mortem, with maximum losses of 19% being achieved by the end of the 24‐h incubation period. 4. At 0°C, shear force values increased from 2.94 kg/cm2 to 4.34 kg/cm2 between 30 and 90 min post‐mortem while the muscle pH was > 6.5. At all other temperatures, increases in shear force values were not detected until 380 min post‐mortem when the muscle pH had fallen to 5.9 and rigor mortis had set in. At all times after 380 min, however, the muscle strips incubated at 0, 5 and 40°C had lower shear values (range 3.17 to 5.49 kg/cm2) than those incubated from 10°C to 30°C (range 5.06 to 7.22 kg/cm2). 5. A significant quadratic relationship was found between the degree of shortening and subsequent cooked meat tenderness, in which peak toughness occurred at 30% shortening. This would suggest that the actual extent of muscle shortening per se has an important role to play in determining the tenderness of chicken post‐mortem. Consequently, with unrestrained chicken muscle, where extensive shortening occurred at 0°C and 40°C (i.e cold‐ and rigor shortening) the cooked meat was more tender than that subjected to intermediate post‐mortem temperature regimens.

Buyse, J.; Adelsohn, D. S.; Decuypere, E.; Scanes, C. G.

doi: 10.1080/00071669308417628pmid: 8242406

Abstract 1. Diurnal—nocturnal changes in food intake, gut storage of ingesta, food transit time and heat production were studied in male broiler chickens reared under a 14L:10D lighting schedule (lights on from 06.00 to 20.00 h). 2. Food consumption during the scotophase was negligible. Peak food consumption during the photoperiod occurred at the beginning of the photoperiod and in the late afternoon. 3. During the photoperiod, the crop and proventriculus/gizzard contained only small quantities of ingesta. However, at the beginning of the scotoperiod, dried ingesta content of crop and proventriculus/gizzard increased by 10.5‐ and 2.76‐fold respectively. This increase was followed by a gradual decrease towards the end of the scotoperiod. 4. Food transit time during the scotoperiod was significantly longer than that during the photoperiod. 5. The daily pattern of heat production closely followed the 14L:10D lighting schedule. Total heat production during darkness averaged 53% of total heat production during the photoperiod. 6. It was estimated that the storage of energy (as ingesta) in the crop and proventriculus/gizzard, followed by its gradual release and the increased food transit time during the night, contributed 75.5% of nocturnal energy needs. It must be recognised that these mechanisms play a major role in the energy balance of the growing chicken during periods without food intake.

Karasawa, Y.; Umemoto, M.; Koh, K.

doi: 10.1080/00071669308417629pmid: 8242407

Abstract 1. Single Comb White Leghorn adult cockerels were fed on 50 g/kg protein diet, 200 g/kg protein diet or 50 g/kg protein diet plus urea and in vitro ammoniagenesis from urea and uric acid in the caeca was determined. 2. Four‐fold protein intake caused about 4.6‐fold increase in caecal ammonia production from urea (P < 0.05), and tended to increase it from uric acid as compared with 50 g/kg protein‐fed birds. 3. Dietary urea significantly increased caecal ammonia production from urea and uric acid by about 2 and 3 times as much as those of control birds, respectively (P < 0.05). 4. It is concluded that increased protein intake and the feeding of urea are able to induce ammoniagenesis from urea and uric acid in the caeca of fowls.

Denbow, D. M.; Hobbs, F. C.; Hulet, R. M.; Graham, P. P.; Potter, L. M.

doi: 10.1080/00071669308417630pmid: 7694779

Abstract 1. An experiment was conducted to investigate the effects of feeding supplemental tryptophan during the two weeks before market on growth, mortality during transportation, meal quality and brain neurotransmitter concentrations in male turkeys. 2. Brain serotonin, 5‐hydroxyindoleacetic acid and norepinephrine concentrations were increased dose‐dependently with 1.0, 2.0 and 3.0 g/kg supplemental dietary tryptophan. 3. Supplemental dietary tryptophan had no effect on body weight gain, food intake, food efficiency or mortality. 4. Carcase and individual thigh weights were significantly heavier in those birds fed l.0 g/kg supplemental tryptophan.

Noble, D. O.; Picard, M. L.; Dunnington, E. A.; Uzu, G.; Larsen, A. S.; Siegel, P. B.

doi: 10.1080/00071669308417631pmid: 8242408

Abstract 1. Growth, food intake, and food preference were measured in two experimental lines (White Rocks and White Leghorns) of chickens fed diets varying in content of lysine, methionine, or tryptophan. Diet A was balanced in all amino acids, while the remaining 6 diets were moderately ( ∼ 30%) or slightly ( ∼ 15%) deficient in either lysine, methionine, or tryptophan relative to NRC recommendations for broiler diets. 2. Body weight and food utilisation efficiency of White Leghorns at 10 d of age were not affected by diet, whereas the lower concentrations of lysine and methionine depressed these traits in White Rocks. 3. Tryptophan deficiency reduced food intake of White Leghorns, but not White Rocks. 4. With choice feeding of balanced and deficient diets from day 10 to 16, preferences between the diets were minimal for White Leghorns, whereas for White Rocks there was an almost immediate preference for the balanced diet, followed by lack of preference or preference for the deficient diet. 5. Apparently for some genetic stocks there is rapid adjustment to deficiencies in these amino acids with overconsumption, followed by compensation for preference of the balanced diet. The response, however, will vary depending on the deficient amino acid.