Live Shrink Research Articles

Effect of transportation distance on the physiological condition and carcass traits of kampong chickens

This research aimed to investigate the effect of transportation distance on the physiological conditions and carcass traits of kampong chickens. Two hundred and twenty-five male kampong chickens were transported for distances of 30 km, 60 km, and 90 km, departing from three villages. Their physiological conditions were observed for up to 12 hours after having reached the final destination, and they were slaughtered after 45 minutes of lairage. The results showed that the transportation distance had a minor influence on the male kampong chickens' physiological conditions on arrival and on resulting carcass traits. Decreased oxygen consumption and metabolism rates were observable only eight hours after the rest period, without further effects on body temperature, tonic immobility, and blood triglyceride levels. There were no significant changes in live shrink, liveability, and carcass production from various transportation distances. However, a significant percentage increase in live shrink, accompanied by a significant decrease in visceral weight, was noted after transportation distances above 60 km. There was a significant decrease in the percentage of drumstick weight and a minor decrease in overall carcass quality, derived from bruising on the thighs. No significant changes were noted in graded carcass quality, meat water-holding capacity, pH, lactic acid, or water content. It was concluded that transportation distances up to 90 km were physiologically tolerable to kampong chickens, imposing minor negative impact on carcass traits.

The effects of simulated transport on the muscle characteristics of white-feathered end-of-cycle hens

Transportation of end-of-cycle hens (EOCH) may result in birds’ experiencing metabolic stress, which changes muscle characteristics. This study evaluated the impacts of simulated transport on muscle characteristics of white-feathered EOCH (65–70 wk). The factorial arrangement included treatments of T/RH (-10°C uncontrolled RH [-10], 21°C with 30 [21/30] or 80% RH [21/80], 30°C with 30 [30/30] or 80% RH [30/80]), duration (4, 8, 12 h), and feather cover (105 well-feathered [WF], 105 poorly-feathered [PF]). A total of 210 hens/replicate/farm (farm=block; 3 total) were tested during the simulated transport. Crates (one/duration/replicate), divided in half for each feather cover (seven hens/side), were placed in a climate-controlled chamber. Prior to exposure, hens were fasted (6 h). BW was taken pre- and post-exposure, and the difference was calculated as live shrink. Post-exposure to the test conditions, birds were slaughtered and carcasses were analyzed for muscle characteristics. Data were analyzed as a randomized complete block design (farm of origin as block) with ANOVA (Proc Mixed, SAS 9.4; significance declared at P ≤ 0.05). Duration resulted in more weight loss for the birds (P < 0.01). Final pH measures (30 h post-mortem) were higher in hens exposed to -10 than 21/80, 30/30, and 30/80 and this difference was exacerbated with time (breast P < 0.01 and thigh P = 0.01). For muscle color, breast and thigh (both feather covers; P = 0.01) were darker in the -10 treatment while redness values were higher in EOCH exposed to this treatment (breast and thigh P < 0.01). Additionally, thigh muscle redness was higher in PF hens (P < 0.01). Thaw and cooking losses were impacted by T/RH and duration (thaw loss P = 0.03 and cook loss P = 0.04). Cook loss was also influenced by T/RH and feather cover with PF hen muscles losing less water during cooking in the -10 treatment (P = 0.01). Overall, the largest impact from transport was found in hens exposed for a longer duration to -10 antemortem compared to other treatments, demonstrating a significant impact on muscle characteristics from ante-mortem stress.

Factors affecting live shrink loss in commercial broilers

The study was aimed at assessing the extent of live shrink loss (%) experienced by the broilers during transportation from the points of production to marketing centres. A total of 2.42 million broilers weighing 4717 MT brought by 1248 truck loads into Chennai city, Tamil Nadu, India for marketing were involved. The study period covered three different seasons namely rainy, winter and summer, the distance of transportation was classified as less than 100 km, 101-200 km, 201-300 km and above 300 km and the duration of transportation was classified as less than three hours, 3-6, 6-9 and above nine hours. The season of transport did not influence live shrink loss (%), while a linear increase in such a loss was witnessed with increase in both the distance or duration of transport. Consequent economic loss due to live shrink loss suffered by the Indian poultry meat industry was estimated to be around INR. 2,905 crores annually. Administration of B complex vitamins and ascorbic acid at the suggested levels were found to be useful in significantly (P  0.01) reducing live shrink loss during transportation of broilers.

Effect of transportation and holding period on broiler meat quality

The purpose of this study was to determine the effects of stress of transportation and holding periods before marketing on meat quality of broilers brought into urban areas from far off production points for marketing. The meat quality parameters like breast and thigh muscle pH, shear force value for tenderness and water holding capacity (WHC) were studied among broilers transported over long (>300 km) and short (100-200 km) distances and also during holding period. Distance of transport of broilers was found to influence shear force value significantly (P  0.01) and muscle pH (breast and thigh muscle) and WHC were not affected by the same. Comparatively, long distance transport of > 300 km resulted in less tender meat than short distance transport for 100-200 km. The live shrink loss (%) increased upto day-2 of holding and the birds were found to recoup body weight and reverse the trend after that. The breast muscle pH also rose upto day-2 and came down afterwards. The broiler meat was found to be the most tender on day-2 of holding, while WHC was the highest on day-4. Microbial quality of drinking water and litter at the holding pens were very poor. Long distance travel and holding periods before marketing influenced the meat qualities of the broilers.

The effects of simulated transport conditions on the muscle tissue characteristics of white-strain layer pullets

The objective of this study was to evaluate the effects of temperature (T)/relative humidity (RH) combinations and exposure duration (D) on the muscle tissue characteristics of layer pullets during simulated transport. While layer pullets are not processed for meat, muscle physiology can be used as an indicator to assess welfare. Pullets (n = 240) were randomly assigned to 1 of 5 T/RH combinations (−15°C uncontrolled RH [−15], 21°C 30%RH [21/30], 21°C 80%RH [21/80], 30°C 30%RH [30/30], and 30°C 80%RH [30/80]) and 2 D (4 or 8 h) in a 5 x 2 factorial arrangement (3 replications). Birds were weighed before exposure, crated (density 45.5 kg/m2) and exposed to the conditions above. After exposure, birds were weighed (live shrink calculated) and slaughtered using a small-scale facility. Postslaughter, carcasses were eviscerated, and an initial pH was obtained from the right breast and thigh. Final breast and thigh pH and color values (lightness [L∗], yellowness [b∗], and redness [a∗]) were obtained 30 h postslaughter. Left breast muscles were frozen and analyzed for thaw and cook loss 4 wk postslaughter. Data were analyzed as a randomized complete block design via ANOVA (Proc Mixed; SAS 9.4), with farm of origin as block. Differences were considered significant when P ≤ 0.05. Live shrink (kg) was higher for pullets exposed to 30/30 and 30/80 compared with those exposed to 21/80 (P = 0.04) and for pullets exposed for 8 h compared with 4 h (P < 0.01). Breast muscle thaw loss (%) was higher in pullets exposed for 4 h compared with 8 h (P = 0.01). Breast and thigh muscle a∗ were higher for pullets exposed to 30/30 compared with 21/30 (P = 0.02). Thigh muscle b∗ was lower for pullets exposed to -15 compared with 21/80 (P = 0.05). Breast b∗ was higher for pullets exposed for 8 h compared with 4 h (P = 0.04). The results from this study demonstrates that increasing exposure D had minor effects on pullet muscle characteristics. In addition, layer pullets coped well with thermal stressors associated with simulated transport.

Simulated transport of well- and poor-feathered brown-strain end-of-cycle hens and the impact on stress physiology, behavior, and meat quality

Transportation of poultry is stressful, especially for end-of-cycle hens (EOCH) experiencing metabolic stress. The aim of this study was to evaluate the effects of simulated transport on well- and poor-feathered brown-strain EOCH. The study (5 × 3 × 2 factorial arrangement) consisted of 5 temperature and relative humidity (RH) combinations applied directly at crate level (−10°C uncontrolled RH [−10], +21°C 30%RH [21/30], +21°C 80%RH [21/80], +30°C 30%RH [30/30], or +30°C 80%RH [30/80]), 3 durations (4, 8, or 12 h), and 2 feather covers (well [WF] or poor [PF]). Hens (n = 540) from 3 commercial farms were housed for a 3- to 5-d adaptation period, then feed was withdrawn before treatment exposure (crate density 54.5 kg/m2). Data collected included chamber conditions, feather condition score, behavior, blood physiology, core body temperature, mortality, and meat quality. Data were analyzed (randomized complete block design) using ANOVA; significance declared at P ≤ 0.05. Time spent performing thermoregulatory behaviors increased for hot (30/30 and 30/80) and cold (−10) treatments. Mortality only occurred in hens exposed to −10 and increased with longer duration. Cold exposure impacted meat quality, resulting in higher thigh pH and lower L∗ (lightness) and b∗ (yellowness). Prolonged exposure duration resulted in dehydration, indicated by blood physiology (hematocrit and hemoglobin) and live shrink. PF hens struggled with thermoregulation in −10, while WF hens struggled in 30/30 and 30/80. These results demonstrate that EOCH exposed at crate level to hot (+30) conditions experience thermal stress, while hens exposed to cold (−10) are unable to cope, compromising welfare and meat quality.

Effects of cold exposure on physiology, meat quality, and behavior of turkey hens and toms crated at transport density

The impact of cold exposure while crated at a density characteristic of transport (83 kg/m2) was assessed in 12-wk-old turkey hens and 16-wk-old toms. Turkeys (72 toms, 72 hens) were randomly divided into 3 male and 3 female groups: 2 moderate 20°C groups with either 30% or 80% RH and a cold group exposed to –18°C, with uncontrolled, high RH. Groups of 8 birds (one replicate unit) were observed in a climate-controlled chamber for 8 h prior to slaughter. Core body temperature (CBT), live shrink, heterophil-lymphocyte ratio (HLR), and change in blood glucose levels were assessed; meat quality measures included thigh and breast muscle pH and L*, a*, and b* color values. Significance was declared at P ≤ 0.05. Live shrink in hens exposed to –18°C (2.8%) was greater (P = 0.001) than those in the 20°C treatments (1.5%). CBT in hens had a tendency to decrease (P = 0.070); no differences in Δ blood glucose or HLR were detected. Thigh pH was higher in the –18°C treatment (hens: 6.39; toms: 6.08) than in both 20°C groups. Color values (L*, a*, and b*) were measured 27 h postmortem. In the –18°C exposed hens, breast L* values were lower, and thigh a* and breast b* values were higher than in both 20°C treatments. No differences were detected in live shrink, CBT, HLR, or color values among toms. Behavior differences were noted between treatments; more time was spent huddling, shivering, preening, and with feathers ptiloerected in cold-exposed turkeys. Generally, cold exposure resulted in higher live shrink, darker meat with greater redness, and a tendency for CBT and blood glucose to decrease, with larger male turkeys experiencing fewer changes.

Influence of hot exposure on 12-week-old turkey hen physiology, welfare, and meat quality and 16-week-old turkey tom core body temperature when crated at transport density

The influence of hot conditions on 12-week-old turkey hens and 16-week-old toms while crated at transport density was evaluated. Forty-eight hens and 48 toms (8 birds per flock × 3 flocks × 2 humidity levels) were used in neutral treatments (trt; 20°C), and 16 hens and 16 toms (8 birds per flock × 1 flock × 2 humidity levels) were used in the hot trt (35°C). Birds were placed in crates at a transport stocking density of approximately 83 kg/m2, then inside a pre-conditioned chamber for 8 hours. Live shrink, core body temperature (CBT), heterophil/lymphocyte (H/L) ratio, and breast and thigh pH and color were recorded. Differences were declared significant at P ≤ 0.05. Live shrink after exposure to the 35°C trt (4.92%) was greater (P < 0.0001) than when birds were exposed to 20°C (1.48%). The 35°C trt (P < 0.0001) had higher Δ CBT (final minus initial) compared to the 20°C trt. The 35°C trt also caused higher (P < 0.0001) H/L ratio, 4.07 vs. 1.57 for the 20°C trt. Breast (P = 0.0110) and thigh pH levels (P < 0.0001) measured 27 h postmortem were lower for the 35°C trt at 5.64 and 5.73 compared to the 20°C trt at 5.70 and 5.92, respectively. Breast meat from birds exposed to 35°C was darker (P < 0.0001), while the color of thigh meat was unaffected. Toms quickly became distressed in the hot conditions, forcing those tests to be aborted. Only CBT data were analyzed. The CBT increased at a mean rate of 0.09°C/min for hens at both RH levels, while the CBT of toms increased at 0.12 and 0.18°C/min when exposed to 35°C, 30%; and 35°C, 80%, respectively. Exposure to hot temperatures caused higher CBT, greater live shrink, and greater H/L ratio. Toms were more greatly affected than hens to the hot trt, with CBT increasing at a greater rate.

Broiler chicken thigh and breast muscle responses to cold stress during simulated transport before slaughter

The effect of acute cold exposure was assessed on broiler physiology, breast and thigh muscle metabolites, and meat quality. In total, 160 male birds at ages of 5 and 6 wk were exposed to temperatures of -9 to -15°C (cold stressed) and +20°C (control) in a simulated transport chamber for 3 h before slaughter followed by 0 or 2 h of lairage. Bird physiology parameters, including core body temperature, live shrink, blood glucose, and muscle temperature, were assessed. Core body temperature was monitored every minute using i-Button data loggers, and live shrink and blood glucose were assessed. Total glucose and lactate concentrations at 30 h postmortem, as well as ultimate pH (pH(u)), color, and water-holding attributes were evaluated on pectoralis major muscle of breast and iliotibialis muscle of thigh. Birds were grouped based on their microclimate temperature to control and cold-stressed groups (0 to -8, -8 to -11, and -11 to -14°C). Significant (P < 0.05) decreases in core body temperature and breast and thigh muscle temperatures were observed at simulated transport temperatures below 0°C. In addition, higher (P < 0.05) live shrink and lower blood glucose values were observed as a result of 3-h exposure to temperatures below 0°C, exacerbated as temperature decreased further below -8°C. Thigh muscle was almost depleted of glycogen reserve compared with a significant but small reduction in breast muscle glycogen when exposure temperature was below -8°C. Similarly, much greater effects were observed on thigh pH(u) and quality attributes compared with breast. In addition, 84% incidence of the dark, firm, dry quality defect was observed in thigh meat (pH(u) > 6.4, L* < 44) compared with 42% incidence of dark, firm, dry in breast meat (pH(u) > 6.1, L* < 46) when transportation temperature was below 0°C. Results of this study showed that thigh muscle was affected more severely than breast muscle by exposure to cold temperatures before slaughter.

Effect of acute cold exposure, age, sex, and lairage on broiler breast meat quality

The effect of acute cold exposure on bird physiology, muscle metabolites, and meat quality was assessed in 360 male and female broilers at 5 and 6 wk of age, exposed for 3 h to temperature ranges of -18 to -4°C and a control of +20°C, by using a simulated transport system followed by 0 or 2 h of lairage. Core body temperature (CBT) was recorded, and the microclimate temperature and RH surrounding individual birds were monitored. Birds were classified based on the temperature in their immediate surroundings. Exposure to temperatures below 0°C resulted in a decrease (P < 0.05) in blood glucose and an increase in live shrink. During the 3 h of exposure to -8°C or lower, CBT dropped substantially. Temperatures below -14°C caused lower glycolytic potential and lactate concentrations. Five-week-old birds showed darker and redder breast meat with higher ultimate pH (pH(u)), less cook loss, and higher processing cook yield at temperatures below -8°C compared with warmer temperatures and with 6-wk-old birds exposed to similar temperatures. No difference in meat quality was observed between the 2 ages at temperatures below -14°C. Males had a greater decrease in CBT and had breast meat with higher pH(u) compared with females. The 2-h lairage resulted in darker breast meat with higher pH(u) at exposure temperatures below -14°C and with higher water-binding capacity and processing cook yield at temperatures below -11°C. A high (>57%) incidence of dark, firm, and dry breast meat [pH >6.1 and L* (lightness) <46] was observed at temperatures below -14°C. A 2-h lairage resulted in an additional 20% increase in the incidence of dark, firm, and dry meat at temperatures below -8°C. Results of this study showed that older birds coped better with extreme cold conditions compared with younger birds. Furthermore, it would be beneficial to limit the length of lairage before processing after exposure to acute cold to improve bird welfare and reduce meat quality defects.

Effect of carbohydrate supplementation provided through drinking water during feed withdrawal on meat and liver colours in broilers

BACKGROUND:The effect of saccarose supplementation provided through drinking water during feed withdrawal on meat and liver colour was investigated in a total of 50 broilers (five floor pens with 10 broilers) at 43 days. Treatments consisted of: (1) full-fed control broilers fed the standard broiler diet and water for the full 10 h (control); (2) fasted broilers receiving only water (FW); (3) 1 g (0.01SW); (4) 2 g (0.02SW); and (5) 3 g (0.03SW) saccarose L−1 supplemented water for the 10 h. The CIE colour values representing lightness (L*), redness (a*), and yellowness (b*) were measured on raw livers, breast and thigh meats. RESULTS:Full-fed broilers had lower dressing percentage, higher abdominal fat and liver yield and lighter thigh meat coloration than the FW birds (P < 0.05). The 0.02SW and 0.03SW resulted in live shrinks that were lower (P < 0.05) than those found in FW broilers. The 0.02SW and 0.03SW resulted in liver colours that were lighter than those found in FW and 0.01SW birds but darker than from control birds (P < 0.05). CONCLUSION:It was concluded that saccarose supplementation during feed withdrawal appears to have a measurable impact on live shrink, and lightness of liver and thigh meat colour in broilers. Copyright © 2007 Society of Chemical Industry

Effects of replacement finisher feed and length of feed withdrawal on broiler carcass yield and bacteria recovery

A study was conducted to determine the effects of a replacement finisher feed (RF) on carcass yield and carcass bacteria recovery. RF is a commercial formulation of a D-glucose polymer (maltodextrin) with added salts and vitamins. Commercial male broilers (41 d of age) were given either RF or control-feed (traditional starter feed) for 8 h, followed by feed withdrawal for 0, 4, 8, or 12 h before processing. During processing, whole carcass rinses (WCR) of pre-eviscerated (feathers, feet, and heads removed) and eviscerated carcasses were analyzed for recovery of bacteria. Body weight at initiation of feed withdrawal (catch weight) or at slaughter (dock weight) did not differ significantly due to type of feed. Live shrink, as a percentage of live weight, increased significantly with time off feed. Birds fed RF exhibited significantly lower live shrink than the birds fed the control feed at 8 and 12 h after feed withdrawal. This difference between types of feed, RF or control, was approximately 0.1% per hour of feed withdrawal. Type of feed or length of feed withdrawal did not affect Campylobacter, coliform, or Escherichia coli counts recovered from WCR of pre-eviscerated or eviscerated carcasses. These data demonstrate that feeding RF to broilers for 8 h before initiation of feed withdrawal may reduce live shrink without affecting carcass Campylobacter, coliforms, or E. coli recovered.

Effect of a short-term feed outage on broiler performance, live shrink, and processing yields

This study was conducted to investigate the effect of a 12-h feed outage at various times prior to slaughter on subsequent broiler performance, live shrink, and processing yields. Broilers were full-fed or subjected to a 12-h feed outage followed by a refeeding period of 12, 24, or 48 h. Bird live weights or feed consumption was monitored during the outage and recovery periods. Birds were subjected to a 10-h feed withdrawal period and were slaughtered using simulated commercial conditions. Carcass weights were recorded through processing for yield determinations. The 12-h feed outage affected female broilers more than male broilers. Although all birds lost weight during their respective feed outage periods, birds were able to consume enough feed upon refeeding such that no significant differences in final live weight were detected at the initiation of feed withdrawal. Female broilers processed after a 12-h refeeding period had significantly larger gall bladders (by weight) as compared to the gall bladders of birds in the other treatments. Other processing parameters were not significantly affected by treatment. A 12-h feed outage and feed replacement prior to normal preslaughter feed withdrawal does not significantly affect processing yields, provided sufficient feed is replaced for at least 12 h prior to feed withdrawal. Because total feed consumption did not change following feed outage replacement, feed must be sufficient to compensate for that not consumed during the outage.

Effect of Transport Cage Height on Broiler Live Shrink and Defecation Patterns

A series of eight trials was conducted to determine the effect of transport cage height on broiler defecation patterns during holding. Prior to treatment, broilers were held in pens with free access to feed and water. In each trial, birds were randomly placed into nine experimental cages, allowing a bird density of 447 cm2/bird. Cages were constructed of wire with perforated wooden tops set at internal heights of 15.2 cm (short), 22.9 cm (normal), or 68.6 cm (tall). The “normal” height was determined as an average for commercial broiler transport cages. Cages with broilers inside were weighed, placed over preweighed manure catch pans, and held for 8 h at 26°C; the cages and the pans were reweighed to determine live shrink and excreta weight. In the first two trials, birds held in the short cages had a significantly greater live shrink than the broilers in the normal or tall cages. However, observations that the cage designs might have adversely affected ventilation led to a redesigning of the tops using wire fabric to improve ventilation. In the following six trials, cage height had no significant effect on live shrink (4.2%) or excreta (1.8%). These results indicate that transport cage height, relative to bird posture during transport, had no significant effects on live shrink or defecation patterns of broilers.

The Effect of Holding Temperature on Live Shrink, Processing Yield, and Breast Meat Quality of Broiler Chickens

The effects of antemortem holding temperatures on live shrink, processing yields, and breast meat quality of broiler chickens were evaluated. A total of 462 broilers was reared to 45 d of age using conventional husbandry practices, removed from feed and water, and cooped 12 h prior to slaughter. During the 12-h feed withdrawal and holding time, the birds were held at 25, 29.5, or 34 C. Birds were individually weighed at cooping, prior to slaughter, and during processing to determine live shrink and processed carcass yields. The breast meat was removed at 2 or 24 h postmortem and was used to determine hot and cold boned meat pH, R-value, sarcomere length, meat color (lightness, redness, and yellowness), cooked yield, and shear value. The birds held at 34 C showed the significantly greatest live shrink, 5.7%, compared to those held at 29.5 or 25 C with 3.9 and 3.2% shrink, respectively. Birds held at 34 C exhibited significantly lower processed carcass yields based on initial catch weight, but when calculated using postshrink weights, there were no significant differences between treatment groups. For breast meat harvested at 2 h postmortem, the birds held at 25 C had higher R-values, redness, and yellowness values and lower cooked meat yield and shear values. For breast meat harvested at 24 h postmortem, the birds held at 25 C had higher pH, R-values, and redness. These results support earlier reports that holding conditions may dramatically effect live bird shrink and apparent yields (based on calculation denominator) but have relatively little effect on subsequent breast meat quality, regardless of postmortem deboning time.

Antemortem Holding Temperatures and Broiler Breast Meat Quality

The two major factors affecting consumer acceptability of poultry meat are color and tenderness. The objective of this study was to determine the effect of antemortem holding temperatures of 7, 18, and 29°C (45, 65, and 85°F) 12 hr prior to slaughter on broiler breast (Pectoralis major) meat quality. Four individual trials were conducted, using a total of 243 commercial broilers. Birds held at 29°C had a significantly greater live shrink, 6.20% compared to 3.75 and 3.82% for those held at 7 and 18°C, respectively. There were no effects on blood loss or chill water uptake. Breast fillets from broilers held at 29°C had a significantly lower pH, lower cook loss, and higher shear value than breast fillets from broilers held at 7 and 18°C. Holding temperature did not affect muscle lightness or redness, but 29°C caused more yellowness. These results indicate that holding live broilers at elevated temperatures may negatively affect live shrink and broiler breast meat quality.

Influence of Ascorbic Acid on Broiler Shrink and Processing Yields

Two experiments were conducted to determine the effect of ascorbic acid (Vitamin C) supplied in the water for 24 h prior to catching on live shrink, processing yields, and meat quality of broiler chickens. In each experiment, 480 broilers were randomly assigned to 24 pens and were given either tap water or tap water supplemented with 973 ppm ascorbic acid for 24 h. Both treatment groups were then cooped, held for 8 h, and slaughtered using conventional methods. Birds were processed for measurement of yield, chill water uptake, drip, breast meat yield, breast meat moisture, and texture. In Experiment 1, the ascorbic acid treatment resulted in a significant increase in dry yield (prechill) with and without giblets and in chilled yield without giblets when calculated as a percentage of New York dressed weight. In Experiment 2, the weight of gastrointestinal waste was significantly lower for the birds treated with ascorbic acid. Of the 76 total measurements in the two trials, only four were significant, with three having some degree of autocorrelation. It was concluded that ascorbic acid had no effect on five shrink, normal processing yield, breast meat yield, breast meat moisture content, or breast meat cooked texture.

Effect of Feed Withdrawal on Yields, Muscle pH, and Texture of Broiler Breast Meat

The effects of various feed withdrawal times on yields, pH, and shear values of breast meat deboned 4 h post-mortem (PM) were determined. A total of 144 commercially reared female broilers was obtained from the holding area of a local processor, and housed for 5 days in floor pens to recover from the stress associated with transport to the plant. After 5 days, the birds were placed in one of two finishing batteries for 48 h prior to feed withdrawal treatments. Feed withdrawal times were 0, 8, 16, or 24 h prior to slaughter. Measurements included live shrink, prechill and postchill carcass yields, breast meat yield, pH at 2 and 4 h PM, and shear values.There was a progressive loss in body weight as feed withdrawal time increased. The 0-h withdrawal treatment resulted in the lowest prechill yield. Quadratic effect of feed withdrawal on shear values was significant. Breast meat from the 0-h withdrawal treatment required more force to shear, 7.09 kg, than did the meat from the 8 and 16 h treatments, 5.84 and 5.78 kg, respectively, meat from the 24-h treatment required 6.01 kg. The results indicate that feed withdrawal schedules can affect not only the carcass yields but also the objective texture of broiler meat deboned 4 h PM.

Effects of Barley Variety, Test Weight and Physical Form on Feeding Value of Barley for Swine

Three experiments involving 623 growing-finishing pigs were conducted to evaluate the effects of barley cultivar and test weight on animal and carcass characteristics. Despite the variation in CP and acid-detergent fiber content of the barley cultivars utilized in Exp. I, there were no differences (P>.10) in performance or carcass measurements. In addition, performance of pigs receiving pelleted barley-based diets was not different (P>.10) from that of pigs receiving the meal-form corn-based diet. There were no differences in performance (P>.10) among the barley cultivars or between the barley-based diets and the corn-based diet in Exp. II. However, differences were noted for dressing percentage (P<.05) and percent lean (P<.01) in Exp. II while no differences (P>.10) were noted for hot carcass weights, adjusted backfat, adjusted loin eye area and quality score. Azure barley samples having test weights of 50 and 63 kg/hl (39 1/2 and 49 1/2 Ib/bu) were mixed to provide barley lots of various test weights in Exp. III. When fed in meal form, ADG declined and F/G increased as barley test weight declined. The effects of declining test weight were of lower magnitude when the barley-based diets were fed in the pelleted form. Pigs receiving corn-based diets or pelleted barley-based diets had similar ADG and F/G values when the barley had a test weight in excess of 59 kg/hl (46 Ib/bu). In general, carcasses from pigs fed barley-based diets were more desirable than carcasses from pigs receiving corn-based diets. Live shrink of barley-fed pigs was not greater than that of pigs fed diets based on corn until test weight of the barley declined below 56 kg/hl. These data demonstrate that pelleted barley-based diets can support performance comparable to that obtained with corn-based diets when both contain equal and adequate levels of available lysine, available methionine plus cystine and available phosphorus.

EFFECTS OF FASTING AND WATER RESTRICTION ON CARCASS SHRINK AND PORK QUALITY

One hundred and twenty market weight (90 kg) pigs were allocated at random to one of three treatments: immediate slaughter and 24 h or 48 h without feed or water after arrival at an abattoir. All pigs were removed from feed 17 h before arrival at the abattoir. Weights of body organs and the digestive tract full and emptied of digesta were recorded along with warm carcass weight. After chilling for 24 h a pork chop 25 mm thick was removed along with the commercial ham and belly from the left carcass side and frozen for later quality determinations. Live weight shrink over 48 h amounted to 6.8 kg with 75% (5.1 kg) of this loss being attributed to loss in carcass weight. The 24-h holding period also resulted in a significant loss in carcass weight (3 kg). Approximately 20% of the total shrink over 48 h was due to a reduction in digestive tract contents. Body organs showed little change in weight over the 48-h holding period apart from the liver which was reduced in weight by 14.6%. Final longissimus muscle pH was increased and muscle luminosity (fresh longissimus, cured m. semimembranosus and m. biceps femoris) decreased for both the 24-h and 48-h holding treatments but did not result in any dark, firm and dry meat. Drip loss in pork chops decreased with increased ante-mortem holding time. However, processed yields for hams and bacon were not significantly influenced by the holding period pre-slaughter. It was concluded that the time from last feeding to slaughter should be minimized to avoid losses in carcass weight and slightly darker fresh and processed meat. Key words: Fasting, carcass shrink, carcass quality, processed yield