Diet Density and Glucose Water Affect Broiler Shrinkage Broiler weight loss, or shrink, can be significant when feed and water are withdrawn from market-age birds before slaughter. An AAES study in- vestigated how shrink and carcass component yields were affected by varying diet density and adding glu- cose to water during the initial fasting period. Male broilers were reared on deep litter and fed either high density (HD) or low density (LD) starter (1-21 days), grower (21-35 days), and withdrawal (35-42 days) diets. The three HD diets contained 22.6, 20.6, and 18.5% crude protein, and 1,475, 1,496, and 1,516 kilocalories (kcal) of energy per pound, respectively. LD diets contained 21.4, 19.5, and 17.7% crude protein and 1,396,1,416, and 1,436 kcal per pound, respectively. At 42 days, all birds were weighed and provided either water or 10% glu- cose solution for six hours after feed removal in pens. Birds were re- weighed before slaughter and pro- cessing at the AU Poultry Science Re- search Processing Plant. Broilers reared on HD diets were significantly heavier than those reared continued on page 2 K: RESEARCH UPDATE 1993 c OULTRY Restricted Light Program Maximizes Growth, Prevents Problems Maximum broiler growth gener- ally occurs with near-continuous light, but rapid growth rate may cause cir- culatory and skeletalproblems. Broiler survival can be improved by provid- ing light that approximates daylength, thus reducing feed intake. However, broilers subjected to extended peri- ods of darkness may develop a higher incidence of breast blisters. An AAES study used restricted light treatments (as seen in the table) with the addition of one or two peri- ods of light to stimulate bird move- ment and prevent breast blisters. Stan- dard management procedures were used, and birds were processed and deboned at 49 days of age. Live body weight, chilled carcass weight, and percentage Grade A car- casses were greatest in the treatment that provided two periods of light during the dark phase. In this treatment, 16 hours of con- tinuous light were followed by three two-hour pe- riods of darkness. The dark periods were alternated with one-hour light periods. This is expressed in the table as 16L:2D:1L:2D:1L:2D. Total mortality, feed efficiency, weights of parts, and incidence of breast blisters were not significantly different among treatments, although the 16L2D:1L:2D:1L:2D program still resulted in the best numbers. The 16L:2D:1L:2D:1L:2D treat- ment provided performance equiva- lent to near-continuous light and may have greater impact on strains that have high incidence of blisters. J.A. Renden, E.T. Moran, Jr., and S.A. Kincaid CARCASS AND YIELD COMPONENTS OF MALE BROILERS (Ross x Ross) EXPOSED TO FOUR LIGHT PROGRAMS Light program' Variable 23L:1D 16L:8D 16L:3D:1L:4D 16L:2D:1L:2D:1L:2D Body weight, Ib ........ 6.3 6.2 6.3 6.5 Chilled carcass, lb..... 4.3 4.2 4.3 4.5 Abdominal fat, lb ...... .13 .13 .13 .14 Wings, Ib .................. .50 .49 .50 .52 Drumsticks, Ib .......... .60 .60 .61 .63 Thighs, Ib ................ .67 .66 .67 .70 Tenders, Ib. ............. .19 .18 .19 .20 Fillets, Ib .................. .84 .80 .82 .86 Grade A, pct. .......... 57.8 45.5 58.7 59.9 Breast blister, pct ...... 33.2 33.9 25.2 27.2 Mortality, pct. ........... 8.5 4.0 3.0 5.5 Feed efficiency, g:g ... 1.85 1.86 1.86 1.84 1 Hours light:hours dark. 1 j ,4AIA Aeica;A EXPRIEN STATION AI:IKN UNIVESITY * I fA Character of a New Foodborne Pathogen Escherichia coli 0157:H7 has re- cently emerged as a recognized food- borne pathogen, and most recently has been implicated as the cause of a major foodbome disease outbreak in- volving hamburgers from a fast-food chain in the western United States. Although most types of E. coli are not harmful to humans, this type (0157:H7) is highly virulent and can cause severe health problems and even death. Because E. coli 0157:H7 has only recently emerged as a foodborne pathogen, little is known regarding its behavior in foods, including poul- try products. To date, poultry has not been involved in disease outbreaks. According to the U.S. Department of Agriculture, broilers taken directly from processing plants are free of this bacterium. However, other studies do show that poultry products can be- come contaminated with this patho- gen, probably from cross contamina- tion as these products move through food processing and distribution chan- nels. Thus, there is keen interest in knowing the growth and survival characteristics of this pathogen in poultry products. To this end, AAES research is fo- cusing on defining the conditions un- der which E. coli 0157:H7 can persist in poultry products and survive cook- ing processes. Such research is di- rected toward the development of safe handling, processing, and cooking guidelines. Much of this work has initially focused on developing highly sensi- tive laboratorymethods, which would lead to more accurate data. Research has shown that cells of E. coli 0157:H7 thathavebeen subjected to treatments, such as freezing or undercooking, are difficult to detect by traditional meth- ods, even though these cells are still alive and would pose a health risk if consumed. An evaluation of different micro- biological methods for recovering these treated (injured) cells led to the identification ofamicrobiologicalme- dium (PRSA + MUG) that is highly effective for recovering injured E. coli 0157:H7 and for differentiating this pathogenic type from nonpathogenic Composting Poultry Carcasses the Alabama Way Alabama's broiler industry faces the challenge of responsibly disposing of 800 tons of cull and dead birds each day. When properly managed, composting is a safe, relatively inexpensive, and environmentally sound method for convert- ing carcasses into a valuable byproduct. Poultry compost may be safely applied to crop or pasture land as a soil amendment and fertilizer when used at recommended rates. AAES research has revealed valuable information for poultry growers who want to establish composting facilities. For example, straw once was used as a composting medium, but AAES studies indicate that litter alone provides a suitable medium. Carcasses, litter, and water in a ratio of 1:3:0.25 comprise the composting formula. Once composted, carcasses can be successfully used as the primary medium in a second composting cycle. Other studies revealed that harmful bacteria can be rapidly inactivated. Two-stage composting with aeration is required to destroy these pathogens. This process involves transferring the material to a secondary bin, where a well- managed composter will generate temperatures above 130OF for three consecu- tive days. Such temperatures can destroy many avian and human disease causing organisms. J.P. Blake, D.E. Conner, and J.O. Donald types. Furthermore, these studies in- dicated that some testing methods cur- rently being used are inadequate and can lead to inaccurate results if used for evaluating the safety of cooking processes for food products. In other studies, ithas been shown that different isolates of E. coli0157:H7 vary in their ability to survive cook- ing. An isolate originally obtained from retail pork demonstrated sig- nificant heat resistance and was sub- sequently used to determine the abil- ity of this pathogen to survive cook- ing in lean (3% fat) and high fat (11% fat) poultry meat. Addition of fat in- creased the ability of the pathogen to survive heating. As in other meats, fat in poultry protected E. coli 0157:H7 from the heat of cooking. Tempera- tures of greater than 140 0 F may be required to provide a reasonable mar- gin of safety in such products. Subse- quent research will be done to verify this under commercial cooking con- ditions. Data from studies so far verify that the use of safe food handling practices, including proper hygiene and adequate cooking temperatures, is the best means of preventing foodborne disease. D.E. Conner Broiler Shrinkage, continued on LD diets, regardless of water treat- ment. Abdominal fatweight and yield were highest on birds reared on HD diets and given glucose. Birds reared on LD diets lost less weight when given glucose. Availability of glucose during the initial stages of feed withdrawal ap- peared to alleviate shrink losses, pre- sumably by reducing fat and protein catabolism. Use of glucose or com- mercially available products, which are often supplemented with electro- lytes and vitamins, during periods of stress (temperature extremes, feed withdrawal, catching-crating, and live transportation) has been shown to re- duce shrink losses and increase prod- uct yields. S.F. Bilgili and E.T. Moran, Jr. I I ' I Age, Sex, and Feathering Rate Influence Broiler Skin Strength Skin contributes significantly to the appearance and quality of broiler carcasses, and skin strength is an im- portant element in ensuring a quality product. AAES research is helping to determine what factors improve skin strength in poultry. Skin-related problems, such as cuts and tears due to weak skin, fre- quently occur during processing and cause substantial economic losses to the broiler industry in the United States. Cuts and tears on skin ac- counted for 4.6 and 6.2% of the total downgrades in 1986 and 1990, respec- tively. Skin integrity of broilers is evalu- ated either by assessing the extent of cuts/tears encountered during pro- cessing or by determining the skin breaking strength. Genetics, sex, nu- tritional factors, flock management, and various feed additives have been shown to affect skin quality of broil- ers. An AAES- developed skin punch method has been used to measure the elastic properties of chicken skin. This method was used to evaluate the age- related changes in broiler skin strength. The studyusedmale and female broilersfrom two strain-crosses (SC) differing genetically in feathering rate, such as slow and fast-feathering lines. Seven hundred and twenty birds were raised to 56 days of age in floor pens by follow- ing standard manage- ment procedures. Start- ing at seven days of age and at weekly intervals thereafter, skin punch measurements were made on five randomly selected birds within sex a Skin strength of both female broilers increased li age. However, skin punc was higher in males than f( figure). Female broilers a marketed at younger ag food markets as compare grown to heavier weights ( for de-boned broiler meat The differences betwe SC were limited to skin dis which is an indirect meas Salinomycin, Amprolium, and Cocci Control Coccidiosis Salinomycin, Amprolium, and Coccivac were shown in an AAES study to provide broiler breeders ad- equate protection against acute coccidiosis and to allow breeder re- placements to develop immunity to the bacterial disease. Arbor Acres chicks were placed in six pens (165 birds per pen) where the litter was seeded with Eimeria acer- vuline, E. maxima, and E. tenella, the bacteria that cause coccidiosis. Birds in two of the pens were treated with either Salinomycin at 60 parts per mil- lion (ppm) for birds up to three weeks and 40 ppm, four to 12 weeks; Amprolium (113.5 ppm, 0-12 weeks); or Coccivac (one dose on day three). At eight weeks, some of birds in each pen were caged, fed nonmedicated feed for 48 hours, and inoc E. tenella, E. maxi-ma, and eggs. Signs of disease we: nondetectable intreated gr nontreated groups had severe traces of the bact droppings. Almost all tr had minor or no intesti while allnontreated birds many severe. Average wE treated birds was 497.18 pared to 13.47 gram nontreated. None of three treatn differences in egg prodi consumption/conversion duction performance, or ume and concentration. L.A. Martinez, G.R. McDaniel, ar Skin pu 7 6 5 0F 4, 3 2 0 7 1' nch strength, kg Females A ales 4 21 28 35 42 49 56 Days ain-cosses0-7- Skin punch strength measurements. nd SC. elasticity. Skin from slow feathering male and SC was less elastic as compared to nearlywith those from fast-feathering SC. :h strength The data generated in this study emales (see provide baseline information on the ire usually developmental pattern of skin es for fast- strength in male and female broilers. d to males Current research is focusing on influ- older ages) ence of nutritional factors (vitamin C products. and zinc) and medicinal feed addi- !en the two tives on skin strength and quality. placement, S.F. Bilgili ;ure of skin vac Recycling Works Best with Feed ulatedwith and Daylength E. acerline Restrictions re virtually roups, while AAES research has shown that noderate to egg producers can decrease the dura- eria in fecal tion and increase the effectiveness of eated birds layer recycling programs by using nal lesions, daylength and feed restrictions con- had lesions, currently. -ight gain of A hen's laying capacity declines grams, com- to nonprofitable levels after about one is for the yearinproduction.Atthatpoint, recy- cling is required to prepare layers for nents made a second production cycle by stimu- uction, feed lating regression and regeneration of 1,live or pro- the reproductive tract. semen vol- Single Comb White Leghorns that nd M.K. Eckman continued on page 4 3 AgeSex an Feaherng ate nflenc Recycling, continued had been laying for 37 weeks were subjected to one of four treatments that included combinations of these feed and daylength restriction regi- mens: (A) 84 days of free choice feed; (B) nine days of fasting, 33 days of limited feed, and 42 days of free choice feed; (C) 84 long daylengths; (D) or 42 short daylengths followed by 42 long day-lengths. In general, the combination of feed restriction and short daylength most rapidly and effectively accomplished the goals of recycling - termination of egg production, decrease in body weight and fat, and stimulation of reproductive tract regression and molting. Egg productionby hens sub- jected to short daylengths increased most rapidly and attained the greatest levels during the last week of the study. These hens would be expected to have the best post-recycling pro- duction. R.J. Lien Broiler Quality Suffers From Lack of Phosphorus Phosphorus is expensive to pro- vide in most broiler feed, but the cost is warrantedbecause ithelps carcasses withstand the stresses of processing, thus increasing product value. AAES experiments showed a strong relationship betweenphospho- rus adequacy and carcass quality. In these tests, some broilers were given feeds with recommended levels of phosphorus, while others were fed 10% less of the nutrient for compari- son. Weight gain during the first three weeks ofproductionwaslessforbroil- ers onreduced-phosphorusfeed;how- ever, birds given inadequate phos- phorus had a distinct advantage in feed conversion, which was promi- nent prior to marketing. Live hauling increased weight loss before slaugh- ter, regardless of phosphorus treat- ment. Processing increased bruising near the hock in birds on the low- phosphorus diet, and bruising was worse in birds subjected to live haul- ing. Deformed drumsticks also in- creased with low phosphorus, but transportation did not effect this prob- lem. When chilled carcasses were fur- ther processed, there were deboning problems in the broilers given less phosphorus. Additional breakage of the femur and separation of the rib cage during deboning increased labor during meat removal. There also was increased blood splash, particularly of the thigh meat. An unexpected disadvantage of providing adequate phosphorus is a higher death rate due to leg disorders and other problems. However, this increased mortality does not outweigh the advantages offeedinganadequate amount of the nutrient. E.T. Moran, Jr., and M.C. Todd Calcium Recommendations for Optimal Performance (Phase 1) Inaneffortto produce larger eggs, egg producers will often limit the amount of calcium (Ca) in feed during Phase I (weeks 20-36). AAES research indicates that limiting the percent of Ca in feed may be restricting produc- tion and shell quality. Many feeds formulated for this phase of production limit the percent dietary Ca to 4% or less. This upper limit has been placed on percent di- etary Ca because of the belief that if Ca is increased enough to obtain a constant Ca intake, as feed intake de- creases, egg size will be reduced and production andfeedconsumptionwill be adversely affected. This upper limit may have been sufficient in past years, when hens typically consumed 20 to 21 pounds of feed per 100 hens per day. How- ever, it now is common for birds to peak in production while consump- tion is only 16 to 17 pounds per 100 hens per day. If hens are eating less, they will not be consuming enough Ca if the percent Ca is restricted in feed. An AAES study was conducted to determine if optimizing eggshell and skeletal strength by manipulat- ing dietary Ca had any adverse effects on egg size, production, or feed con- sumption during this phase. For the study, W 36 pullets (20 weeks of age) were randomly divided into 12 treat- ments with six treatments housed at 60-74 0 F and six treatments housed at 70-84 0 F. Hens in each treatment were fed diets containing 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0% Ca from 20-32 weeks of age. Results indicate that increasing dietary Ca causes a significant linear increase in egg production. Because of the improvement in feed efficiency of today's bird (as low as 2.2 pounds per dozen eggs during peak produc- tion), they simply cannot optimize per- formance on percent dietary Ca levels that were adequate just a few years back. Environmentaltemperature had no influence on egg production and there were no interactions among en- vironmental temperatures and Ca lev- els. Egg specific gravity was directly related to dietary Ca level. Within two weeks, hens housed in the cool environment had signifi- cantly higher egg specific gravities. This indicates that hens housed in the warm environment were not receiv- ing enough Ca, even at the highest Ca level. The higher dietary Ca levels had no adverse influence on egg weight. Egg weight of hens fed the 4.5 or 5% Ca was even numerically greater than hens fed 2.5 to 3% Ca. This result was expected because hens fed the higher Ca levels had a greater egg specific gravity (more shell). Therefore, it is believed that attempts to maximize egg weight by limiting Ca may actu- ally be reducing egg size up to 0.2 grams simply because of reduced shell weight. Decreasing environmental temperature increased egg weight an average of 0.8 grams. Hens housed in the cool environment consumed seven grams more feed per hen per day than hens housed in the warm environ- continued on page 5 I I .I.Vlali~ I~C=U~ IUIILLUI