INFLUENCE OF SUPPLEMENTAL MANGANESE AND ZINC ON LIVE PERFORMANCE AND CARCASS QUALITY OF DIVERSE BROILER STRAINS'

Transcription

1 ~ BlWApplied Poultly Science, nc NFLUENCE OF SUPPLEMENTAL MANGANESE AND ZNC ON LVE PERFORMANCE AND CARCASS QUALTY OF DVERSE BROLER STRANS' N. E. COLLNS2 and E. 'E MOW, JR. Poultry Science Depament, Auburn University, Auburn, AL Phone: (344) W 2617 FM: (334) ~ Primary Audience: Nutritionists, Processors, Extension Specialists DESCRPTON OF PROBLEM Manganese (Mn) and zinc (Zn) are of particular interest to broiler production because of their association with normal growth and skeletal soundness. Current requirements for Mn and Zn are 60 and 40 ppm, respectively, and both levels are based largely on historical data [l]. The escalating growth rate of commercial broilers has brought these values into question. Previous work in this laboratory with a single commercial broiler strain and progressive ration supplementation with combined Mn and Zn suggested minimal benefits from enhanced fortification [2]. However, antagonisms between the two tran- sition series elements may have masked advantages of supplementation. Similarly, modem broiler strains may differ in their responses to dietary mineral treatments. An experiment was conducted to evaluate the effects of fortifying commercial-type feeds with substantial levels of Mn, Zn, or their combination on the Live performance, carcass quality, and skeletal soundness of two diverse broiler strains. lmatems AND METHODS Birds of two commercial broiler strains known to differ in growth characteristics and body composition were hatched at the Auburn 1 Alabama Agricultural Experiment Station Journal Number To whom correspondence should be addressed

2 COLLNS and MORAN Research Report 229 University Poultry Research Farm. Chicks were feather sexed at hatching; males of each strain were randomly allocated to four mineral supplement groups (four replicate pens/ treatment, 21 birddreplicate pen). Birds were placed on used pine shaving litter in floor pens (ca. 45 ft2) and provided feed and water ad libitum. Temperature and ventilation of the open-sided house were thermostatically controlled and lighting was continuous. Chicks were vaccinated for Marek's, Newcastle, and infectious bronchitis diseases at the hatchery. mmunization for infectious bursal disease followed 14 days after placement. Three basal rations were formulated, starter being fed to 21 days of age, grower from 22 to 42 days, and finisher from 43 to 49 days Table 1). Starter was fed in crumble form, TABLE 1. Basal diet comoosition NGREDENT STARTER GROWER FNSHER l l % (as is) whereas others were offered as complete pellets. The only nutritional difference between treatment groups was the amount of supplemental Mn and Zn, both of which were provided in sulfate form by the trace mineral premix (Table 2). Levels of all other nutrients satisfied current NRC recommendations [l]. Body weight and feed efficiency measurements were made for each production phase. Mortalities were necropsied and categorized as ascites, sudden death syndrome (SDS), leg problems, or other causes. At 49 days of age, all birds were transported in coops to the Auburn University pilot processing plant and held overnight for processing the next day. Online processing of treatment groups was random [4]. Carcasses were static chilled in slush ice for approximately 4 hr; abdominal fat was then removed and carcass defects were itemized [5]. Carcasses were held overnight in slush ice and subsequently deboned on stationary cones by personnel from a commercial processing plant following established procedure. Resulting parts consisted of wings, fillets (Pectoralis major), tenders (Pectoralis minor), skinless boneless thigh meat, drumsticks, and residual carcass debris. Femurs and tibiae were stored at -2O"C, thawed, and cleaned of all adhering tissue. Maximum width of the midshaft and of each epiphysis, as well as the total length of the femurs and tibiae, were measured with calipers. Bone mineral densities at the midshaft and the region immediately below each epiphysis were then determined [6], followed by Protein (%) AMED (kcallg) TABLE 2. Mn:Zn supplement treatments and feed analvses SUPPLEMENT NUMBER AddedA AnalyzedB /44' /

3 230 Mn, Zn, AND BROLER STRAN nstron evaluation of breaking strength [7l. Bone fragments were then sectioned into proximal, midshaft, and distal regions. After pooling by region and replicate pen, bone sections were homogenized and subsampled for ash analysis [8]. Data were evaluated by analysis of variance employing a factorial arrangement of Mn:Zn supplement level and broiler strain in a randomized complete block design. Blocks corresponded to pen areas of the production house. Computations followed the General Linear Models procedure of SAS [9] and multiple mean comparisons were conducted by Tbkey's (HSD) test. RESULTS AND DSCUSSON Body weight, feed efficiency, and livabil;ty were generally not influenced by supplementary Mn and Zn (Table 3), although a main effects interaction was apparent for ascites mortality. Supplements without Mn elevated ascites death (3-6 wk of age) in Strain A, whereas Mn inclusion minimized this response. Strain B exhibited the opposite trend, albeit to a lesser degree (Figure 1). Losses from sudden death syndrome (3-7 wk of age) varied among mineral supplement groups, although advantages from any single treatment were unclear. Leg problems were not encountered. Failure to obtain a broad live performance response to supplemental Mn and/or Zn when dietary levels exceed requirements is in agreement with previous reports [2, 10, 111. Performance differences by broiler strain were as anticipated. Supplemental Mn and Zn also did not alter processed carcass weights, yield, or percentage abdominal fat (Table 4). Evaluation of carcass defects indicated a marginal relationship with mineral supplementation (Table 5). ncidence of back and thigh scratching in Strain A tended to increase with mineral fortification, whereas the opposite effect was noted with Strain B (Figure 2). ncidence of red tail, a minor carcass defect, varied with mineral treatment alone, generally increasing with fortification rate. However, the percentage of grade "A" carcasses remained similar among treatments. Deboning yields were likewise unaltered by mineral levels (Table 6). Dissimilarities in abdominal fat and breast meat yield between broiler strains characterized expected differences in carcass composition. Previous reports suggest that reduction in long bone dimensions occurs with inadequacies of Mn and Zn [l2, 131. n the present study, however, total length as well as midshaft and epiphyseal widths of the femurs and tibiae were unaffected by dietary Mn and/or Zn levels (Table 7). Simple observation of the tibiae frequently revealed an apparent alteration in epiphyseal cartilage, possibly associated with Mn and Zn availability. All tibiae were subjectively scored for incidence and degree of alteration as previously described [2]. Contrary to expectations, the scores described an apparent inverse relationship with Mn and Zn supplementation rate (Table 8). Subsequent radiographic scans measuring bone mineral density indicated differences with supplementation rate only for the distal femur region (Table 9). Mineral densities for the tibiae were unaltered (proximal = , midshaft = , and distal = g/cm2). Femurs and tibiae subjected to nstron stress each demonstrated similar load resistance, regardless of Mn and Zn levels (maximum load: femur = ; tibia = 32.3k0.4 kg). Ash content of both bone types, regardless of region, was likewise unaltered by the dietary Mn:Zn treatments (Table 10).

4 COLLNS and MORAN Research Report 231 TABLE 3. Live performance of male broilers from two diverse strains fed excessive levels of supplemental Mn and/or ZnA AGE 0-3 wk 3-6 wk 6-7 wk 4 ~ values 1 represent the average from eight replicate pens of 21 birds/pen. No main effects interactions occurred, :xcept as footnoted. %eed consumed/body weight gain, corrected for mortality respective of period. 5EM values are from ANOVA of actual percentages, whereas probabilities are from arc sin square mot percentage transformations. 'Main effects interaction, 3-6 wk (Figure 1).

5 JAPR 232 Mn, Zn, AND BROLER STRAN Strain A Strain B 1j 0 0:oo --.. m 0: :O Supplement Level 180: 150 FGURE 1. Percentage ascites mortality (3-6 wk), as influenced by Mn:Zn supplementation level and broiler strain (Ps.05) TABLE 4. Carcass yield for male broilers from two diverse strains fed excessive levels of supplemental BPost-chill carcass weight. Carcass as percentage of 7wk, full-fed weight.

6 COLLNS and M O M Research Report 233 A B SEM l strain^ 0 0:oo 0: :O 180:150 Supplement Level FGURE 2. Percent carcass back and thigh scratching, as influenced by Mn:Zn supplementation level and broiler strain (Ps.05)

7 234 JAPR Mn, Zn, AND BROLER STRAN TABLE 6. Deboning yields of male broilers from two diverse strains fed excessive levels of supplemental Mn and/or ZnA BRibcage, back, skin, and other waste remaining after removal of all other parts. MEASUREMENT Length FEMUR (mm) 79.2k0.26 Proximal Width Midshaft Width 11.OkO.04 TBA (mm) 108.8k ko O k0.07 Distal Width 19.4k k0.08 *All values represent the average of 32 pens (Grand MeankSEM), each providing ca.10 bone pairs of each type, Therep.ere no si ificant treatment differences nor interactions (~2.08 TABLE 9. Femur mineral density of male broilers from two diverse strains fed excessive levels of supplemental Mn and/or ZnA CONTRAST PROXMAL DSHAFT DSTAL Mn:Zn TAE3LE8. Degree of alteration of proximal tibia tissue from male broilers of two diverse strains fed excessive levels of supplemental Mn and/or ZnA COFTrRAsr % NCDENCE Normal ndicated Mn:Zn SEM!5TuN A B SEM a NS NS NS A All values represent the average from eight replicate pens, each providing ca. 10 bone pairs. values represent the average from eight replicate pens, each providing ca. 10 bone pairs. REGON Proximal FEMUR ("/. 37.4k0.23 TBA (W 42.3k0.27 Midshaft 38.8k k0.43 Distal 37.4k values represent the average of 32 pens (Grand MeankSEM), each providing ca. 10 bone pi.= of each type, There were no si ificant treatment differences nor interactions (~2.08

8 Research Report COLLNS and MORAN 235 CONCLUSONS AND APPLCATONS 1. Supplementing broiler feeds with substantial levels of inorganic Mn and/or Zn generally did not improve live performance or processing yields of male broilers. 2. Carcass yields and incidence of defects were not influenced by supplemental Mn and/or Zn above established requirements. 3. Skeletal integrity did not apparently benefit from heightened Mn and/or Zn supplementation. 4. Diverse commercial broiler strains responded similarly to dietary Mn and/or Zn fortification. 1. National Research council, Nutrition Reuirements of Poult 9th Rev. Edition. Natl. Acad. -, Washington, DZ 2. Collins, N.E and ET. MOT Jr., nfluence of supplemental manganese and zinc on lm rformance and carcass quality of broilers. J. Appl. $oultry Res Revington, W.H., N. Acar, and ET. Moran, Jr., Cupversus tray excreta collections in metabolizable energy assays. Poultry Sci Kill line required 9 min followed by manual transfer to the evisceration line, which required 7 min to chillin Processing conditions were stunning at 50 v De 25 mamp, and 100 Hz for 8 sec, scaldin at 57 C for 82 sec (Cantrell Machine Co., Gainesville, EA), plucking for 42 sec (Model JM-32 C-M, Meyn USA, nc., Gaincsville, GA), and automated evisceration (Mark V Pritchard Systemate, Atlanta, GA). 5. USDq Poultry Gradin Manual. Agriculture Handbook No. 31, Agriculturaf Marketing Service, Washington, DC. 6. Norland Model 2780 Densitometer (Norland Corp., Fort Atkinson, W) with m source. 7. nstron Model 1011 Computer Controlled Testing System (nstron Corp., Canton, MA) with 50 kg transducer, 20 pts./sec sampling rate, 200 mm/min crosshead REFERENCES AND NOTES speed. Thawed bones were placed across the open end of a cylinder (50 mm diameter for femur, 73 mm for tibia) with force applied to the midshaft. 8. Pooled sections were homogenized by a Waring blender for 1 min. Homogenates were stored at -2O"C, then thawed and sub-sampled 65 ). These samples were dried in ceramic crucibles (105 E 24 hr) and ashed in a muffle furnace (WC, 18 hr). 9. SAS nstitute, SAS User's Guide: Statistics. SAS nstitute, nc., Cary, NC. 10. Gardiner, EE, Lack of response to added dietary manganese of chicks fed wheat-so@ean meal or com-soybean meal based diets. Can. J. Anim. Sci M e a AL, Jr., J.H. B-baugh, and H.W. Titus, A com nson of the growth of chicks fed diets containing difgnt quantities of zinc. Poultry Sci Ceskey, C.D., W.D. Gallup, andlc. Norris, The need for man ese in the bone development of the chick. J. Nutr. 17E Morrison, AB. and H.P. Sarclt, Studies on zinc deficiency in the chick. J. Nutr. 65: