Cooking frozen Turkey: duration, yield and stuffing alterations with solid-state starting temperature.

Frozen pre-stuffed turkeys from 12 week females were conductively cooked at 163°C to an 85°C internal breast end-point. Bread cubes having 50% added water filled crop and body cavity to 20% of weight the turkeys were then frozen. Each of 4 treatments employed 7 carcasses: one was thawed to +5°C with repetitions at -5, -15, and -25°C enabling a regression analysis. Time to attain breast end-point was 44 min when the starting temperature was +5°C, which increased to 63 min at -5°C, and 69 min at -25°C (P < 0.001, Q: quadratic). Thigh temperatures averaged 77°C. Crop stuffing was 80°C when cooking was initiated at +5°C and increased to 84°C as the starting temperatures fell to -25°C (P < 0.01, Q). Body cavity stuffing reached 65°C when the carcass had been thawed prior to cooking, thereafter decreasing to 59 and 60°C when at -5 and -15°C, respectively, before returning to 65°C for the -25°C case (P < 0.01, C: cubic). Total carcass loss was 18.8% when cooking was initiated at +5°C. This increased to 22.6% at -25°C (P < 0.01, Q). Total drip after cooking averaged 23.7% however, the percentage of fat in the drip increased from 51.1% when using +5°C, to 57.2% with carcasses at -25°C (P < 0.05, Q). The stuffing gained in weight, which could be attributed to associated water when thawed, as opposed to frozen (147 vs. 102g, P < 0.05, Q). Stuffing moisture was less when the carcasses had been frozen than if cooked after thawing, particularly for crop (59.4% using +5°C vs. 55.8% frozen, P < 0.05, Q). Fat dominated the DM: increase, which was similar among treatments and both locations (22.6%). Stuffing CP: increased with +5°C carcasses on thawing compared to frozen carcasses, particularly for crop (15.1 vs. 13.2% DM, P < 0.05, Q from +5 to -5°C, respectively). Changes in part yield and meat composition were minor. Heat for ice to change to liquid was the primary basis for alterations when cooking from the frozen state, while cavity stuffing consistently failed to attain a safe temperature.

Effects of flesh attachment on bone breaking and of phosphorus concentration on performance of broilers hatched from young and old flocks.

Two experiments were conducted to 1) assess any differences on breaking force in bones with or without flesh attachment and 2) determine the effects of dietary nonphytate phosphorus (npP) concentration, maternal flock age, and chick sex on live performance and tibia strength of broilers. For experiment 1, sixty chicks were placed in battery cages and selected weekly for removal of both tibiae (15 chicks/wk). Raw flesh was either completely cut from the bone or left intact and broken using a texture analyzer. For experiment 2, Ross 708 chicks (1,220) were hatched of 25- and 65-wk-old breeder flocks, separated by sex, vaccinated, and placed on used bedding across 64 floor pens (18 males or 17 females/pen, 8 repetitions/treatment). Through 28 d, all birds were fed corn-soybean meal diets (22% CP, 3,086 kcal/kg) adequate in all nutrients but npP, which was included at either 0.35 or 0.50%. Individual BW and pen feed consumption (FC) were recorded weekly and corrected for mortality. Each week, 24 birds/treatment were killed for tibia evaluation. Experiment 1 resulted in no differences in breaking force, whether flesh remained or was removed from the bone. In experiment 2, BW was increased with an increase in npP (P<0.001) at the end of the experiment. Both BW and FC were increased (P<0.001) from 0 to 28 d of age in chicks from the 65-wk-old breeder flock. Males had increased (P<0.001) final BW, FC, and tibia breaking forces. Breaking forces were also improved (P<0.001) when npP was increased or chicks were hatched from older breeder flocks. Interactions were present (P<0.05) for npP concentrationx25-wk breeder flock 7- to 21-d BW gain (BWG) and 0- to 28-d FC, npP x chick sex 7- to 14-d BWG and 21- to 28-d feed conversion ratio, and breeder flock age x chick sex 0 d BW and 7- to 14-d BWG. These results indicate that broiler growth and performance can be affected by maternal flock age, chick sex, and dietary npP.

Response of coccidiostat- versus vaccination-protected broilers to gelatin inclusion in high and low crude protein diets.

Experimentation examined if Gly and Ser (Gly + Ser) and Pro from gelatin inclusion in low and high CP feeds would relieve impaired performance of broilers after vaccination for coccidiosis. Broilers in floor pens were fed 20-18-16% or 23-20-18% CP corn-soybean meal regimens from 0 to 8 wk of age such that 1 or more of the most limiting essential amino acid levels were similar across treatments and considered adequate respective of age. Gelatin was included in diets at 2%, which contributed Gly + Ser and Pro levels comparable to using 5% meat meal. Half of the chicks were spray-vaccinated with live oocysts before placement and received nonmedicated feed, whereas the other half received coccidiostat-medicated (salinomycin) feed to 6 wk of age. Vaccination adversely affected live performance in the first 3 wk, which could not be fully compensated to the level of birds receiving coccidiostat by the end of experimentation. Inclusion of gelatin mitigated vaccination response through the first 3 wk, while improving overall live performance of birds fed low CP diets. Gelatin had no effect on carcass composition, but the low CP regimen increased abdominal fat and reduced carcass and breast meat relative to high CP feeds. Vaccination also reduced overall carcass weight; however, part yields were not affected. Males were generally more sensitive to treatments than females. The conditionally essential amino acids Gly + Ser and Pro may be important factors in recovery from live anticoccidial vaccines.

Intestinal cytokine response of commercial source broiler chicks to Salmonella typhimurium infection.

Development of molecular-based immunotherapeutic strategies for controlling Salmonella Typhimurium (ST) infection in poultry requires a better understanding of intestinal and cecal cytokine responses. Accordingly, an experiment was conducted to measure changes in intestinal cytokine expression when commercial source broiler chickens were challenged with a nalidixic acid-resistant ST. Ross broiler chicks were nonchallenged with ST (control treatment) or challenged by orally giving 7.8 x 10(6) cfu at 4 d of age (STC treatment). Each treatment consisted of 4 replicate pens with 14 chicks per pen. Expression levels of proinflammatory cytokines, interferon-gamma, and antiinflammatory interleukin (IL)-10 were determined at 5 and 10 d postchallenge (PC). Intestinal flushes were also collected from each treatment at 7 d PC to estimate IgA and IgG. Results showed an upregulation in IL-1beta mRNA in STC chicks at 5 d PC. By 10 d PC, the expression of IL-1beta was further increased and accompanied by an upregulation of IL-6 and interferon-gamma mRNA, whereas IL-10 mRNA expression decreased. It was concluded that ST induced an intestinal mucosal inflammatory response in commercial source broiler chicks less than 2 wk of age.

Nutrition of the developing embryo and hatchling.

Nutrient needs central to satisfactory egg incubation well-being undergo several major changes from fertilization until the reliance of the chick on feed. Glucose is central, with the initiation of incubation until the chorioallantois accesses O(2) to use for fatty acid oxidation. Nutrient recovery from albumen and yolk is largely commensurate with body assembly through to completion of the embryo by 14 d. Remaining albumen mixes with the amniotic fluid and is orally consumed until initiation of emergence. A portion of the albumen is absorbed by the small intestine to expand body glycogen reserves. The residual not absorbed contains digestive enzyme contributions and enters the yolk sac through its stalk at the jejunum and ileum. Interaction of the albumen-amnion digestive enzyme mixture with yolk sac contents leads to diverse alterations that influence subsequent use of lipids. Rapid removal of very low-density lipoprotein ensues, until pipping with triglycerides, expanding body fat depots while cholesterol deposits in the liver. A concurrent translocation of Ca from shell mineralizes the skeletal system while also crossing yolk sac villi for deposition on phosvitin-based granules accruing in its lumen. Loss of chorioallantois with pipping and the start of pulmonary respiration predispose a dependence on glycolysis to support emergence. Small intestinal villi progressively reorient their enterocytes from macromolecule transfer to competence at digestion and absorption after hatching. Mobilization of body fat complements contributions from the yolk sac to provide fatty acids for generating energy, heat, and water while also combining with hepatic cholesterol for membrane expansion and continued development. Calcified granules evacuate the yolk sac to further skeletal mineralization in the absence of shell contributions. Egg mass, its interior quality, and turning during early incubation directly influence the ability of the embryo to access nutrients and provide resources to support emergence and the transition of the chick to self-sufficiency.

The effect of phytase and glucanase on the ileal digestible energy of corn and soybean meal fed to broilers.

The current research was designed to determine the effect of phytase and glucanase on the energy value of corn and soybean meal (SBM) separately for broilers at various ages. The treatments were arranged as a 2 x 2 x 2 factorial, with 0 or 500 phytase units/kg or with 0 or 500 units of glucanase/kg, supplemented to either corn or SBM, with each combination represented by 6 cages of 10 birds. Diets of pure corn and soybean meal were not supplemented with additional nutrients, and were fed for 3-d periods beginning at 7, 14, or 21 d of age, representing the immature, transitional, and mature digestive tract, respectively. Each experiment was performed on a different group of birds from the same hatch. At the end of each experimental period, the broilers were euthanized and the contents of the ileum, duodenum and jejunum (pooled), and pancreas were removed for analysis. The ileal samples were analyzed for acid-insoluble ash and gross energy to determine the ileal-digestible energy (IDE) of the feedstuffs. The pancreas and duodenal-jejunal samples were analyzed for proteolytic and amylase activity to determine the influence of practical levels of phytate on enzyme activity. Results showed that neither phytase nor glucanase influenced enzyme activity in the digesta or pancreas, suggesting that practical levels of phytate did not influence the activity of proteolytic enzymes or amylase. Phytase did not influence the IDE value of either corn or SBM, and improved DM digestibility of the feed only for corn fed at 21 to 23 d. Glucanase improved IDE in both the corn and SBM diets at all ages, and improved DM digestibility in corn diets at all ages and SBM diets fed at 14 to 16 d. The IDE and DM digestibility of corn and the digesta and pancreatic enzyme activities increased with age, whereas the IDE of SBM was similar among age groups. The relative effect of glucanase on IDE of both feedstuffs was similar among age groups.

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.

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.

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.

Egg quality and hen performance responses to protein-calcium deficiency, cafeteria feeding, and cage density.

Single Comb White Leghorn (SCWL) hens were given feeds (2975 kcal ME/kg) that were marginally deficient in protein (15%) and calcium (3.0%). Negative control was as a mash, whereas an experimental mixture had the same formulation, but 5 of the 15% protein was soybean pellets in place of the meal and 2 of the 3% calcium was oyster shell flakes. A complete cafeteria system acted as a positive control and provided pellets, oyster shell, and a 10% protein-1% calcium mash (2975 kcal ME/kg) separately in a three-compartment trough. Feed treatments were imposed from 24 to 40 weeks of age on hens kept one and two/cage. Performance effects, because of the feed treatments, were not apparent until after 8 weeks of experimentation. Production was sustained by the pellet-oyster shell feed mixture when birds given the complete mash declined. Feeds had immediate effects on egg quality. Egg shell deformation and albumen Haugh values were highest with the complete mash and lowest for the cafeteria system, while the complete mixture was generally between these extremes. Hens kept two/cage consumed more feed than those one/cage and responded similarly to each treatment, but the reduced performance associated with increased density was not alleviated.

Starch digestion in fowl.

Starch is usually the largest single nutrient in feed and provides the greatest proportion of metabolizable energy. Amylose and amylopectin comprise starch and are packed by plants in granular form. Granule stability is a function of the proportions of each polymer and the manner in which they are crystallized. Plant source determines granule size and stability. Grains generally have granules that are smaller and less stable than tuber or legume sources. Pancreatic alpha-amylase is the only enzyme elaborated by fowl that digests starch. Avian and mammalian sources are very similar, and inhibitors would not ordinarily be encountered in practice. The primary products of amylose digestion are maltose and maltotriose which further include alpha-limit dextrins when amylopectin is the substrate. Having starch in granule form reduces polymer access by the enzyme, and digestion difficulties occur in proportion to stability of structure. Moisture combined with heat destabilize granule structure and their use at one time or another in the manufacture of most feeds alleviates digestibility problems. Large amounts of the enzyme are present with the chick at hatch, and the pancreas is more than capable of synthesis commensurate with need. Gelatinization, enzyme adequacy, predominance of starch from grain, and lack of inhibitors account for the relative absence of practical problems involving this nutrient.

Effects of egg weight, glucose administration at hatch, and delayed access to feed and water on the poult at 2 weeks of age.

Eggs from a 42-wk-old small-type turkey breeder flock were weighed and divided into heavy, medium, and light categories relative to the population average. Poults from each category were sexed, then given .5 mL of 50% glucose in saline by either crop intubation (CI) or subcutaneous injection at the neck (SC). Controls did not receive glucose. One-half of the birds from each treatment were immediately given access to feed and water in pens of brooder batteries; the remainder were held 3 days in transportation boxes before placement in other pens of the same batteries. Poult weight at hatching and 3 days later paralleled egg weight. Improvement in 3 day BW occurred after glucose administration and was greater by SC than CI, but these advantages were only apparent when feed and water had been accessible during the interim. Egg weight effects on BW and gain persisted to 2 wk of age, as did the depression from delayed nutrient access; however, the advantage from glucose with poults having early access to nutrition disappeared. Alterations in the proximate compositions of livers and carcasses among treatments were small. Total mortality increased with egg weight when poults received feed and water early after hatching, while the converse occurred when delayed. Deaths were not altered by either glucose or fasting (P greater than .05).

Subcutaneous glucose is more advantageous in establishing the posthatch poult than oral administration.

Poults have been shown to have low carbohydrate reserve after hatching, and glucose at this time improves early performance. Present experimentation examined the effects of .5 mL of 50% glucose in saline 2 h after subcutaneous injection (s.c.) at the base of the head or given as an oral gavage. Timing of administration and slaughter corresponded to when poults would encounter antibiotic-vitamin injection at the hatchery and the subsequent stress of transportation. Live weight after treatments was greater for poults given s.c. glucose than those untreated, whereas oral dosing led to a loss in weight. This weight loss could be wholly attributed to decreased carcass moisture. The s.c. glucose increased yolk sac resorption, and s.c. and oral glucose improved accretion of crude protein and ether extract by the yolk sac and liver-free carcass. Liver glycogen and blood glucose increased to a greater extent from s.c. than from oral glucose. Loss of body water after oral glucose and the poults' reduced efficacy in improving carbohydrate status might be attributed to an immature intestine.

Effects of posthatch glucose on poults fed and fasted during yolk sac depletion.

The advantage of glucose administration after hatching was examined in terms of poult performance and body changes 3 days after administration. A .5-mL dose of 50% glucose in saline was either subcutaneously (sc) injected in the neck or intubated into the crop. Controls did not receive glucose nor were they handled. Controls and poults given glucose were divided into two groups and either brooded with feed and water or kept in transportation boxes and fasted. Poults that were fasted lost weight, and glucose treatments did not alter this loss; however, access to feed and water led to a gain in weight. Those poults given glucose had greater weight gains and feed consumption than controls. Liver, yolk sac, and carcass contained increased moisture in response to glucose when feed and water had been provided, whereas only the carcass expressed this change when the birds were fasted. Most changes to glucose were greater from sc than oral dosing, and neither egg weight of origin nor sex influenced the extent of poult response.

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.

Poult yolk sac amount and composition upon placement: effect of breeder age, egg weight, sex, and subsequent change with feeding or fasting.

Hatching eggs from 48 and 55-week-old Small White turkey breeders were used to examine the yolk sac of these poults. Influences due to flock age, egg weight, poult sex, and a two day postplacement regimen of feeding or fasting were evaluated in a factorially designed experiment. Each variable was found to act independent of the other. Older breeders gave eggs having a greater percentage yolk and with more ether extract than if they were from younger hens. For the most part, these fundamental differences remained with the poult's yolk sac at and after placement. Examining egg weight effects apart from hen age showed that heavier eggs had heavier yolks but their percentage of the total was to the converse and no compositional differences appeared. Poults from large eggs had a greater amount of yolk sac that contained proportionately less ether extract than if they were from small eggs. In total, yolk sac found ca. 12 h after poult removal from the hatcher corresponded to reserves that would remain ca. two days after formal hatching. The yolk sac free carcass failed to exhibit any compositional differences regardless of egg source or weight upon placement, but 48 hr later changes occurred that could largely be attributed to interim yolk resorption. Fasting delayed yolk sac uptake and favored removal of moisture and lipid to a greater extent than protein while the converse was true if access to feed and water was permitted. All parameters were unaltered because of poult sex.

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.

Effect of plane of nutrition from starting to and through the breeder period on reproductive performance of hen turkeys.

Large-type breeder hens were given high (HP) and low (LP) planes of nutrition from day of age to 31 weeks of age. Rearing treatments were then divided, and each was fed HP and LP breeder feeds to 57 weeks. Protein and metabolizable energy (ME) levels of the HP feeds approximated NRC (1977) recommendations, while LP feeds largely involved substitution of corn, fat, and soybean meal for wheat, barley, and oats, such that ME/protein ratio and relative content of essential amino acids were similar between treatments, respective of age. The LP rearing regimen led to reduced hen body weight at 31 weeks. Combining the LP rearing with LP breeder regimen resulted in continuously lighter weights than occurred with the other three treatments to 57 weeks. Carcass fat based on finish grade of sample hens was lower after LP than HP rearing at both 31 and 57 weeks, while the breeder treatments were without effect. Experimental variables neither influenced egg production nor egg weight, but a reduction in the proportion of yolk occurred that was attributable to LP rearing and to a lesser extent the LP breeder feed. Apparent fertility improved with hens that had been LP reared, while feeding the LP breeder led to reduced pip losses, but only if eggs were set within 7 days of being laid. The converse occurred with eggs set after 7 days storage.

Effect of plane of nutrition from starting through the breeder period on the reproductive performance of tom turkeys.

Large type breeder toms were given high (HP) or low (LP) planes of nutrition from hatching to 29 weeks of age. Birds from each rearing treatment were divided and HP or LP breeder rations were fed to 58 weeks. Protein and energy levels of the HP feeds approximated National Research Council (NRC, 1977) recommendations while LP feeds involved substitution of corn, fat, and soybean meal for wheat, barley, and oats. Energy-protein ratio and relative essential amino acid levels were similar between treatment, respective of age. Toms given LP feeds weighed less than HP through the first 9 weeks after hatching, but they were similar thereafter until 29 weeks. Reduction in feed conversion with the LP regimen was only significant during the 18 to 21-week interval. Feed intake during the breeder period was unaffected by treatments. Toms receiving the LP breeder feed reduced their weight, particularly when preceded by LP rearing. Mortality was inversely related to average body weight with each treatment. Reproductive capacity, as judged from semen yield and sperm concentration, was more favorable when toms were reared on LP than HP feeds but only during the first few weeks of the breeder period. The LP feed given through the breeder period also proved more favorable than HP feed, particularly at the end of production. Carcass evaluations at 29 and 58 weeks indicated that the LP regimens reduced depot fat while increasing relative testes weight.

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.