Biomedical subjects

E T Moran

Publications and source records attributed to E T Moran.

At least 19 recordsLinked to original sources

PubMed2006

The effects of suboptimal eggshell temperature during incubation on broiler chick quality, live performance, and further processing yield.

Different incubation conditions can cause eggshell temperature (EST) to deviate from optimum. Two experiments were performed to determine the effect of low EST at the start of incubation and high EST at the end of incubation on hatchability, chick quality, 6-wk live performance, and breast meat yield of broiler chickens. In each experiment, 1,800 eggs from a single flock were divided and set into 2 setters. From 0 to 10 d of incubation, one setter was set to attain an EST of 36.6 degrees C (considered low), whereas the other was set to 37.8 degrees C (the control temperature). Using an infrared thermometer, EST was measured daily on a sample of eggs to ensure treatment intentions. On d 11 of incubation, the temperature of the low EST setter was increased to 37.8 degrees C in synchrony with the other setter until transfer. On d 18 of incubation, eggs from both setters were combined into 2 equal groups and transferred to hatchers. The EST in one hatcher was set to 37.8 degrees C (control) and in the other to 39.5 degrees C (considered high) until 21 d of incubation. Hatched males were placed in battery cages (Experiment 1) or floor pens (Experiment 2) and reared on common feeds to 1 or 6 wk of age, respectively. Low EST in the first 10 d of incubation reduced hatchability, increased BW and chick yield, and reduced 1-wk gain compared with the control EST. Throughout rearing, BW was reduced for low EST chicks compared with control EST chicks; consequently, carcass, fillet, and tender weights were also reduced. High EST in the hatcher increased hatchability, and reduced BW, chick yield, and 1-wk gain compared with control EST in the hatcher. By 3 wk of age, there was no difference in BW between chicks in high EST and control EST treatments. Subsequent carcass and processing yields were also similar. Incubation at the control EST of 37.8 degrees C, particularly from 0 to 10 d, resulted in the best performance overall.

Animals↗

PubMed2005

Dietary tryptophan need of broiler males from forty-two to fifty-six days of age.

Tryptophan requirements of broiler males from 42 to 56 d of age were studied. Ross x Ross 308 chicks were placed in an open-sided house, and provided common starter and grower diets from 0 to 42 d of age. Subsequently, a corn, soybean meal, corn gluten meal, and gelatin combination of feedstuffs provided 0.12% Trp to which 0.04% increments of L-Trp were supplemented at the expense of an isonitrogenous amount of L-Glu to 0.24%. Birds that received diets containing 0.12% Trp exhibited aberrant behavior based on the spillage of considerable amounts of feed from the trough and contamination of adjacent waterers with floor litter. There were reductions in body weight gain, feed conversion, and carcass and breast fillets weights and yields with dietary Trp at 0.12%, but these were not affected at Trp levels at or above 0.16%. Exponential regression analyses showed that body weight gain improved as Trp increased, with maximum overall performance being attained at 0.17%, whereas chilled carcass weight maximized at 0.16% dietary Trp. Nitrogen retention measured using the same experimental feeds and sample birds at 48 to 49 d of age was unaffected by dietary Trp. Plasma uric acid, albumin, total protein, and aspartate-transferase measured concurrently with nitrogen retention were not altered; however, blood glucose was reduced in broilers fed 0.12% dietary Trp. Overall results suggest that broiler males need approximately 0.17% dietary Trp between 42 and 56 d of age, which closely agrees with the NRC (1994) recommendation of 0.16% Trp estimated from modeling for this feeding period.

Animal Feed↗

PubMed2004

Freeze-thaw and cooking effects on broiler breast fillets with extreme initial L* values.

Five hundred broiler males were grown to 56 d and processed under common terms. Front halves were deboned 24 h postmortem to obtain breast fillets, and CIELAB light reflectance was measured on the skin side of each fillet 24 h later. All fillets were bagged and frozen (-20 degrees C) for 5 mo. Then the fillets exhibiting the lowest (dark), median (normal), and highest (pale) L* values 48 h postmortem were thawed (3 d at 4 degrees C) and cooked (internal temperature 80 degrees C). Thawing reduced the L* value in the pale fillets and increased it in the dark ones, and cooking further increased L* value and reduced the differences in L*, a*, and b* between groups. Thawing and cooking losses were not affected by initial L* value until they were combined. Total losses increased with initial L*, which was in parallel with a lower increase in thickness after cooking.

Animals↗

PubMed2004

Valine needs of male broilers from 42 to 56 days of age.

An experiment was conducted using Ross x Ross 308 males to estimate the proportion of dietary valine needed to optimize performance in broilers from 42 to 56 d of age. All birds received common feeds from 0 to 42 d, and then experimental diets were given to 56 d of age. A diet consisting of corn, soybean meal, and corn gluten meal (17% CP, 3.25 kcal of ME/g) having 0.60% valine served as basal feed. All other essential amino acids were above recommended levels. Successive additions of 0.07% of L-valine were isonitrogenously substituted for L-glutamic acid up to a total of 0.81%. Regression analysis (95% of response) indicated that valine at 0.72% of the diet maximized body weight gain, whereas 0.73% optimized feed conversion. Depot fat removed from the abdominal cavity after processing was unaltered, and weights of resultant chilled carcasses maximized at 0.73% valine in parallel with final live weight. The amount of fillets recovered from chilled carcasses optimized at 0.73% valine; however, the incidence of distinctive blood streaks in the meat (splash) progressively increased with valine as did the level of redness apart from streaking, based on light reflectance. Given lysine at 0.85%, a ratio of 0.86 with valine appears to be adequate. The presently determined requirement of 0.73% total valine (0.67% digestible) for broiler males from 42 to 56 d of age is slightly higher than the 0.70% recommended by the NRC.

Aging↗

PubMed2004

Refrigeration and freeze-thaw effects on broiler fillets having extreme L* values.

Eight hundred broiler males were grown to 56 d and processed under common terms while maintaining individual identity. Front halves were deboned 24 h postmortem (PM) to obtain breast fillets, and CIELAB light reflectance was immediately measured on the skin side of each fillet. Fillets were bagged and held at 4 degrees C for 24 h, and then 20 fillets exhibiting the darkest (47.3 to 57.5), lightest (71.1 to 76.4), and median (63.7 to 64.0) L* values were selected and trimmed to best define the pectoralis major. Remeasurement of light reflectance at 48 h PM revealed decreased L* values solely associated with fillets having the highest L* at 24 h. One-half of the fillets representing each category was frozen (4 d at -20 degrees C) and thawed (3 d at 4 degrees C). The L* value, after thawing, decreased from the 48 h PM value, which equivalently occurred in for all L* categories. Although 48 h PM fillets from each L* category were of similar weights, their lengths and widths increased with L* value. Exudate lost with thawing increased with L* value and paralleled decreases in length and width to equalize dimensions among sources.

Animals↗

PubMed2003

Lysine needs of summer-reared male broilers from six to eight weeks of age.

Experimentation was conducted to estimate dietary lysine needed to optimize production of summer-reared broilers between 42 to 56 d of age. Male Ross x Ross 308 chicks were placed in floor pens of an open-sided house and provided common feeds from placement to 42 d of age. During the subsequent 42 to 56 d, birds received a corn-soybean meal basal diet (18% CP and 3,250 kcal/kg ME) established to provide limiting essential amino acids favorably balanced near requirement levels with the exception of lysine. Four 0.10% increments of L-lysine isonitrogenously displaced L-glutamic acid from the basal diet to provide analyzed values progressing from 0.85 to 1.25%. Body weight gain and mortality were not altered as dietary lysine increased; however, feed conversion linearly improved. Chilled carcass yield, amount of abdominal fat, and recovery of skinless boneless breast meats were not affected. Measurements on nitrogen balance and plasma levels of total protein, albumin, glucose, and uric acid taken at 49 d from a concurrent study using sample birds in raised-wire cages and identical feeds also failed to define a requirement. However, plasma aspartic transferase increased to a maximum approximating 1.05% lysine, whereas free lysine concentration linearly increased to the highest level. Overall data supported a lysine requirement no less than 0.95% that was greater than the previous minimum of 0.85% obtained under similar terms without heat stress. Suppression of growth from heat stress appears to reduce the absolute need for lysine; however, increased dietary concentration appears necessary to accommodate depressed feed intake and improve its effectiveness.

Aging↗

PubMed2003

Arginine need of heavy broiler males: applying the ideal protein concept.

An experiment was conducted to determine arginine need of male broilers between the ages of 42 to 56 d, in conjunction with dietary protein approaching a previously advocated ideal amino acid pattern. Ross x Ross 308 chicks were reared in floor pens (32 pens with 35 birds each) of an open-sided house on common feeds until 42 d of age. From 42 to 56 d of age, birds were fed a corn-soybean meal diet (17% CP, 3,250 kcal/kg ME, and 0.85% lysine) having basal arginine at 0.80%, and then progressive additions of 0.15% were made until 1.25% was reached to form the dietary treatments. Final body weight together with body weight gain and feed conversion through the 42-to-56-d experimental period were optimized at 0.98% arginine. Weight of the chilled carcass was optimized at 1.00% arginine, whereas depot fat that had been removed from the abdominal cavity continued to decrease to the highest level of supplementation. Additional total arginine to 1.05% was needed to maximize weight recovery of fillets and total breast meat. An arginine requirement for nutritional purposes approximating 1.00% as advocated by NRC (1994) is in general agreement with present results for live production and meat yield; however, carcass incidence of skin scratch infections and parts defects from processing stresses continually responded until the highest level to suggest that additional amounts would be needed for immunological and connective tissue challenges.

Aging↗

PubMed2003

Methionine and cystine requirements of slow- and fast-feathering male broilers from zero to three weeks of age.

Two experiments were conducted with fast- (Ross x 3F8) and slow- (Ross x 308) feathering broiler males from 0 to 3 wk of age to determine Met and Cys requirements. A corn-soybean meal basal diet was formulated to be deficient in Met and Cys but was adequate in all other nutrients (22.0% CP; 3,050 kcal ME/kg). In experiment 1, diets contained 0.50% dietary Cys with 0.35, 0.40, 0.45, and 0.50% total Met. Feed conversion (FC) of slow- and fast-feathering males improved in a similar manner to 0.50% Met (linear, P < 0.05). Nitrogen retention measured from 20 to 21 d of age optimized at 0.46% Met (quadratic, P < 0.01), regardless of feathering rate. Experiment 2 examined the response to feeding 0.35, 0.40, 0.45, and 0.50% total Cys in diets having total Met at 0.45%. Increasing Cys improved FC that optimized at 0.40% with fast-feathering birds (quadratic, P < 0.01), whereas slow-feathering broilers were not responsive. Nitrogen retention measured from d 20 to 21 did not indicate a difference attributable to feathering but a Cys optimization at 0.43% with both broiler sources. Present experimentation indicates a Met requirement approximating 0.50% is appropriate for broilers 0 to 3 wk of age, regardless of feather rate; however, the estimated Cys requirement for slow-feathering males (0.39%) was less than for fast-feathering (0.44%) males.

Animal Feed↗

PubMed2003

Methionine and cystine requirements of slow- and fast-feathering broiler males from three to six weeks of age.

Two experiments were conducted to first determine Met then Cys needs of broilers from 3 to 6 wk of age and whether differences existed between slow-feathering (Ross x 308) and fast-feathering (Ross x 3F8) males. A corn-soybean meal diet (20.0% CP; 3,150 kcal ME/kg) with graded levels of Met or Cys was offered. The first experiment had dietary Met levels of 0.32, 0.38, 0.44, and 0.50% with surfeit Cys (0.40%). Broilers from both feathering strains responded similarly to supplemental Met. Although body weight was not responsive, F/G improved through to the highest level of dietary Met (linear, P < 0.05). Chilled carcass weight increased with Met (linear, P < 0.05) paralleling F/G; however, no differences were detected in the amount of associated abdominal fat. Breast fillet yield increased with Met to maximize at 0.48% (quadratic, P < or = 0.009). In a satellite study using the same birds in cages and feeds, N retention at d 29 maximized at 0.46% Met (quadratic, P < 0.05). The second experiment had Cys at 0.32, 0.34, 0.38, and 0.46% with Met fixed at a submarginal level of 0.38%. Increasing dietary Cys had no effect on live performance of slow-feathering birds, whereas weight gain of fast-feathering birds achieved maximum at 0.36% Cys (cubic; P < 0.05) with F/G responding similarly. Chilled carcass (cubic, P < 0.002) and breast fillet weights (cubic, P < 0.001) of fast-feathering birds also increased with Cys to maximize at 0.36%, and the amount of abdominal fat was not influenced by feathering or Cys supplementation. Separate measurement of N retention at d 31 failed to detect a difference in protein utilization attributable to feathering, but an optimum was achieved at 0.40% Cys with both broiler sources. Overall results suggest that the Met requirement for broiler males between 3 and 6 wk of age was independent of feathering and approximated 0.46% (95% of the level of maximal response). Cystine requirements once corrected for submarginal Met status indicated a greater demand by fast- than slow-feathering male broilers corresponding to 0.42 and 0.37%, respectively.

Age Factors↗

PubMed2002

Lysine need of heavy broiler males applying the ideal protein concept.

An experiment was conducted to measure the response of broiler males to dietary lysine progressing from 0.75 to 1.15% between 42 and 56 d of age. Chicks (Ross x Ross 308) were placed in floor pens (30 pens having 35 chicks each) of an open-sided house and provided common feeds to 42 d of age. From 42 to 56 d, a corn-soybean meal diet (18% CP and 3,250 kcal/kg ME) having total lysine at 0.75% was supplemented with additions of 0.10% until 1.15%. All other essential amino adds were "ideally" balanced to one another within the limits of practicality assuming 0.85% total lysine. Birds had continuous access to feed, water, and light. Live performance during experimentation was particularly favorable. Weight gain between 42 and 56 d of age was similar among birds receiving all levels of lysine, while feed conversion was optimized at 0.85%. Depot fat removed from the abdominal cavity, yield of the resultant chilled carcass, and the amount of fillet (pectoralis major) cone deboned from the breast were unaltered by dietary lysine level. However, yield of tenders (pectoralis minor) decreased as supplemental lysine increased, whereas the incidence of myopathy (green muscle disease) increased. The lysine requirement of 0.85% as advocated by NRC (1994) for broilers between 42 and 56 d of age is in agreement with present results and may have been predisposed by its favorability of balance with all other essential amino adds.

Adipose Tissue↗

PubMed2001

Male and female broiler responses to low and adequate dietary threonine on nitrogen and energy balance.

This study evaluated nitrogen and energy utilization by male and female broilers that were at 46 and 54 d of age fed diets deficient or adequate in threonine. Birds were reared in floor pens of an open-sided house and were provided diets that met NRC (1994) nutrient recommendations from placement until 6 wk of age. At 42 d, 48 birds (24 per sex) were selected and individually penned in Petersime batteries and were given feeds that were formulated to contain 0.52 or 0.74% total threonine having 18% CP and 3,200 kcal ME/kg. Two 24-h excreta collection periods were conducted on Days 46 and 54 to assess nitrogen and energy recovery. Males receiving adequate threonine had an advantage in retention of nitrogen and recovery of AMEn over males consuming the low threonine diet. Utilization of nitrogen by females was similar at both threonine concentrations, and AMEn corresponded to the concentration recovered by males when threonine was adequate. Inadequate threonine appears to create conditions that reduce recovery of energy by male broilers.

Aging↗

PubMed1999

Evaluation of the parameters needed to describe the overall growth, the chemical growth, and the growth of feathers and breast muscles of broilers.

An experiment was carried out to collect data suitable for testing methods used to describe the potential growth and body composition curves of broilers. Males and females of two commercial broiler strain-crosses were grown to 16 wk of age with birds taken at 0, 2, 4, 6, 8, 12, and 16 wk of age for chemical analysis and for the measurement of feather weight and breast meat (Pectoralis major and Pectoralis minor) weight at these ages. The data were used to test the Gompertz growth equation and the assumption of chemical allometry, as well as to estimate the values of the growth parameters for the different genotypes. Feeding and environmental conditions were intended to be such that potential growth and body composition could be attained. The weights of the chemical components for each of the four genotypes were described in terms of the mature weight of these components, their rates of maturing, and the time taken to reach the maximum rate of growth of each component. Allometric relationships between the weights of the chemical components and that of body protein were estimated. The ratio of ash to protein was essentially constant. Water matured more slowly, and lipid faster, than protein. For males, and for females up to 8 wk, the models were satisfactory. For females after this age, lipid growth was faster than expected from the earlier period, probably in preparation for egg production. There were small, but important, differences in the values of some parameters between the strain-crosses. For each of the four genotypes the changes in weight of feathers and breast meat with time were described in terms of the Gompertz growth function, which described the data very well. The parameters of the function for each component and genotype-mature weight, rate of maturing, and the time taken to reach the maximum rate of growth B were evaluated. For the feathers, the value of the rate parameter was higher than that estimated for the body as a whole. For the two breast muscles, and for their total weight, the value of the rate parameter was similar to that for the body as a whole. There was a simple allometric relationship between the weights of the breast muscles and that of the whole body. As a consequence, the development of the yield of breast meat for a given genotype could be described by the values of the two parameters: mature yield and the allometric exponent. A description of each genotype of interest is seen as an essential first step in using a simulation model either to predict requirements, or to predict the effects of different feeding programs, and environmental conditions, on the performance of broilers.

Animal Husbandry↗

PubMed1996

Effect of glutamic acid on broilers given submarginal crude protein with adequate essential amino acids using feeds high and low in potassium.

Broiler males were examined for their response to feeds containing CP 1 to 2% below levels advocated by NRC (1994) and when supplemented with L-glutamic acid. Crude protein and glutamic acid treatments were imposed in starting, growing, and finishing feeds over 7 wk with K at high and low levels likely to occur in practice (0.80 vs 0.65 to 0.55%). All feeds were formulated to be isocaloric (3.20 kcal ME/g) and satisfy NRC (1994) essential amino acid (EAA) minimum requirements. Improved live weight gain occurred during the first 6 wk with supplementation of glutamic acid to the low CP feed but not when intact protein per se was used to increase CP. A similar advantage in growth was obtained from glutamic acid in response to its addition at equivalence of 1 to 2% CP as well as when dietary adjustments maintained low CP. Response to altered K could not be interpreted because of concurrent differences in glutamic acid and AMEn intakes. High glutamic acid levels did not decrease abdominal fat unless CP increased concurrently, whereas carcass back bruising and drumstick deformations were relieved by supplemental glutamic acid independent of CP. Increased weight gain from glutamic acid was only evident with drumsticks and debris that included the back when carcasses were cone-deboned. Supplemental glutamic acid is believed to improve the rate of connective tissue formation during rapid growth.

Amino Acids, Essential↗

PubMed1996

Carcass yield and weep loss from fast-food cuts after processing broilers using extremes in stunning current and slush-ice chilling.

Six-week-old broilers were compared in yield and weep loss when stunned using either 25 or 125 mA current followed by slush-ice chilling where resultant carcasses were either held static for 4 h or subjected to 45 m of tumbling. Treatments were factorially arranged among the populations of 32 pens (24 birds per pen) that had been reared under common conditions. Tumbling increased chill water uptake, abdominal fat content, and yield of whole carcasses, whereas no differences occurred as a result of the stunning treatments. Carcasses were separated into a nine-piece cut immediately after chilling. All parts lost weight from weepage during the subsequent 24 h, and weep from total parts was greater when carcasses had been tumbled than held static. Keel portion breasts and drumsticks continued a weight advantage from water uptake with tumble chilling, but wings, thighs, and split breast lost this additional water and were similar to those respective parts static chilled. High stunning current led to an increased amount of keel portion breast, regardless of chilling treatment, with subsequent weep not being affected. Alterations in yield that occur because of chilling procedure are substantial and not equivalent among parts, whereas stunning has little impact and is focused on the breast.

Absorption↗

PubMed1996

Lighting programs for broilers that reduce leg problems without loss of performance or yield.

This study tested the effects of light schedules on performance and yields of broiler chickens. In Experiment 1, light treatments during Days 1 to 49 of age were: 1) 23 h light (L):1 h dark (D); 2) 16L:8D;3) 16L: 3D:1L:4D; and 4) 16L:2D:1L:2D:1L:2D. In Experiment 2, Light Treatments 1 and 2 were the same as Treatments 1 and 4, respectively, in Experiment 1; 3) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, the light period was increased by 2 h/wk during Days 15 to 35, and 23L:1D Days 36 to 42; and 4) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, 16L:3D: 2L:3D Days 15 to 21, 16L:2D:4L:2D Days 22 to 28, 16L: 1D:6L:1D Days 29 to 35, and 23L:1D thereafter. In Experiment 1, BW was greater in Treatment 4 than Treatment 2 at 22 (708 vs 642 g) and 49 d (2,948 vs 2,797 g), percentage leg problems was lower in Treatments 2 to 4 (9, 10 and 6%, respectively) than in Treatment 1 (20%), and percentage Grade A was greater in Treatment 4 than Treatment 2 (60 vs 46%) at 49 d. In Experiment 2, BW was greater in Treatment 1 (692 g) than Treatments 3 (617 g) and 4 (620 g) at 21 d, and the incidence of tibial dyschondroplasia was lower in Treatment 2 (3.1%) than Treatment 3 (15.3%) at 42 d. There were no differences for mortality among treatments in either experiment.

Animals↗

PubMed1994

Response of broiler strains differing in body fat to inadequate methionine: live performance and processing yields.

Ross x Arbor Acres (RxAA) and Steggles x Arbor (SxAA) chicks were given all nutrients as advocated by NRC (1984) except for methionine. Corn and soybean meal were the sole CP sources, and both strains were compared when feeds were adequate and deficient in methionine (0 to 3 wk, .65 vs .42% with 24.2% CP and 3.20 kcal AME/g; 3 to 6 wk, .54 vs .46% with 20.7% CP and 3.21 kcal AME; and 6 to 8 wk, .35 vs .30% with 17.8% CP and 3.19 kcal AME, respectively). Cystine exceeded NRC (1984) recommendation with all feeds. Live weights of RxAA broilers were heavier throughout the experiment, but SxAA had the advantage in feed conversion. Adverse effects of low methionine on weight gain were apparent only during the first 6 wk, and SxAA responded to the deficiency more than RxAA from 0 to 3 wk. The SxAA birds had less abdominal fat when processed at both 6 and 8 wk than RxAA. Low methionine increased fat proportions at 6 wk but not at 8 wk. Percentage chilled carcass yield without abdominal fat was similar for each strain and decreased as a result of low methionine at both ages. Low methionine also reduced proportions of skinless boneless breast meat but only at 6 wk and particularly in SxAA birds. The increased ability of RxAA birds to deposit fat enabled additional feed intake, in turn, minimizing repercussion of inadequate methionine.

Adipose Tissue↗

PubMed1994

Continuous submarginal phosphorus with broilers and the effect of preslaughter transportation: carcass defects, further-processing yields, and tibia-femur integrity.

Broiler males were given a series of feeds from 0 to 8 wk having all nutrients advocated by the NRC (1984) and were compared with birds offered feeds with available P continuously 10% below recommendation. At termination, birds in pens were divided for cooping, and coops were either subjected to 6 h of truck transportation and 4 h of preslaughter rest or held stationary for 10 h. High summer temperatures existed throughout experimentation, and low dietary P reduced body weight gain through the first 6 wk, whereas an advantage in feed conversion and mortality occurred from 6 to 8 wk. Weight loss increased when birds were subjected to transportation, regardless of P nutriture, and a portion of the loss was recovered during processing as gain in relative chilled carcass yield. Proportions of abdominal fat and skinless boneless meats from chilled carcasses were unaltered, regardless of treatment. Increased incidence of deformed drumsticks occurred because of low P as did drumstick bruising, which was further accentuated when birds had been transported. Back bruising was prominent when P was adequate and birds were held stationary, whereas the converse occurred with transportation. Tibia length was reduced as a consequence of low P, whereas the femur suffered in terms of decreased mineral density at the epiphyses and resistance to Instron-applied stress. Although transportation in itself did not affect any bone measurement, inadequate P weakened the skeleton to increase likelihood of carcass defects during preslaughter stress.

Animal Husbandry↗

PubMed1994

Lack of interactions between dietary lysine or strain cross and photoschedule for male broiler performance and carcass yield.

The purpose of this study was to test interactions of dietary lysine or strain crosses provided increased lysine with photoschedule on broiler performance and carcass quality. In Experiment 1, treatments were factorially arranged as two lysine levels [control grower and finisher (NRC, 1984) or control grower and finisher plus .15% L-lysine HCl] and two photoschedules [23 h light (L):1 h dark (D) or 14L:10D]. All birds received a control starter feed and dietary treatments were initiated at 22 d of age. In Experiment 2, treatments were factorially arranged as two strain crosses [Peterson x Arbor Acres (PAA) or Ross x Ross (RR)] and two photoschedules (23L or 16L). All birds received standard starter and standard grower and finisher plus .15% L-lysine HCl. There were no lysine by photoschedule or strain cross by photoschedule interactions in this study. The high-lysine diet increased BW, improved feed efficiency, increased lean carcass weight and yield of breast meat, and decreased abdominal fat and yield of thighs. The PAA strain cross had better feed conversion, fewer Grade A carcasses, more back bruises and breast blisters, greater yield of wings and drumsticks, and less yield of breast meat than RR. The 23L had greater BW, better feed efficiency, fewer breast blisters, greater carcass weight (Experiment 1), more abdominal fat (Experiment 2), lower yield of wings (Experiment 1), drumsticks, and thighs, and greater yield of breast meat than the treatments with shorter photoschedules. Increased dietary lysine did not compensate for decreased breast meat yield associated with 14L (Experiment 1).

Animals↗