Housing and Selenium Influences on Feathering in Broilers

2001 Poultry Science Association, Inc.

HOUSING AND SELENIUM INFLUENCES ON FEATHERING IN BROILERS F. W. EDENS1, C. R. PARKHURST, G. B. HAVENSTEIN North Carolina State University, Department of Poultry Science, Raleigh, NC 27695-7635 Phone: (919) 515 2649 FAX: (919) 515 2625 e-mail: [email protected]

Primary Audience: Nutritionists, Production Managers, Purchasing Agents, Researchers

SUMMARY A majority of the broilers produced around the world are sexed on the basis of rapid-feathering females or slow-feathering males, which is facilitated by the presence of the sex-linked, auto-sexing, slow-feathering K gene in males. Recent advances in materials have allowed development of a caging system that is a viable alternative to the traditional floor-rearing regimen. In this study, a comparison was made between the traditional floor- and cage-rearing environments and their influence on feathering of auto-sexing, sex-linked male and female broilers fed at 0.2 mg/kg of feed either NaSe or an organic selenium yeast (OR). Feed conversion ratios, BW, and mortality were not affected by Se source. Feather tracts on the back, breast, thigh, wing, neck, and wing were scored subjectively based on feather size and skin surface covered. Feather scores ranged from 0 (no feathering) to 5 (best feathering) for each tract. The OR induced more rapid whole body feathering in the slow-feathering males as well as in the normal-feathering females. The influence of OR was evident from 21 through 42 d of age. Females had a faster feathering rate than did males. Females approached full feathering at 35 d of age, but males lagged behind females even at 42 d. Feathering of broilers in the conventional house was slightly faster than the feathering of broilers in the cage house. The mechanism for improved feathering rate in normal-feathering females and slow-feathering males given OR has not been determined. Key words: Broiler, cage house, conventional house, feathering, organic selenium 2001 J. Appl. Poult. Res. 10:128–134

DESCRIPTION OF PROBLEM Edens et al. [1] reported that feathering rate of auto-sexed, slow-feathering males was enhanced significantly with dietary supplementation of OR. Enhanced feathering with OR compared with NaSe at concentrations of 0.1 or 0.3 mg/kg diet were observed in trials conducted 1

To whom correspondence should be addressed.

in both the spring and summer seasons. These observations were unexpected even though it had been reported that Se apparently was involved in feathering and feather development [2, 3]. Because poor feathering has been associated with production of broilers in cages [4, 5], an investigation was conducted to determine whether OR could influence the feathering rate of both females and slow-feathering males

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A. E. SEFTON Alltech Biotechnology Center, Alltech, Inc., 3031 Catnip Hill Pike, Nicholasville, KY 40356

EDENS ET AL.: SELENIUM INFLUENCES FEATHERING reared either in a cage system for broilers or in a conventional, litter-covered floor, curtain side wall rearing environment.

MATERIALS AND METHODS

and wings (upper coverts) were scored subjectively on the basis of feather size and skin surface covered at 14, 21, 28, 35, and 42 d of age [1]. Feathering scores ranged from 0, if there were no down feathers, but normally, a score of 1 (poorest) to 5 (best) was assigned for each tract. The regional feathering scores were determined, and scores for the different feather tracts were averaged for a whole body feathering score. Data on feathering were partitioned by sex, dietary Se source, and housing environment. Data were subjected to statistical analysis using the General Linear Models procedure of SAS [9]. Analysis of variance was conducted for each parameter, and the level of significance was set at a minimum at P ≤ 0.05.

RESULTS AND DISCUSSION Body weights were equivalent between NaSe- and OR-fed broilers in both the conventional and cage house (Table 1). Feed conversion ratios were equivalent for birds within a housing environment even though there were very small increases in FCR for those birds given OR (Table 1). However, the major difference in FCR was between housing environments; the birds in the cage house showed a 28-point improved FCR (0.28). There were no mortality differences between housing environments and Se forms (Table 1). These observations on performance were consistent with earlier observations on the performance of broilers given either NaSe or OR [1]. The data from this experiment showed that OR induced more rapid whole body feathering in the slow-feathering males as well as in the normal-feathering females (Figure 1). This influence of OR was evident at 21 d of age and persisted through 42 d of age. These data also showed that the females had a faster feathering rate than did the males throughout the experiment. Females approached full feathering at 35 d of age, but males were still lagging behind females even at 42 d of age. Data were partitioned to study the feathering rate on different body regions (Figures 2 through 7). There was a Se yeast effect on female back feathering at only 21 d of age (Figure 2). At 35 d of age, nearly complete feathering of the backs of females was evident in groups given either

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This project was approved and conducted under the supervision of the North Carolina State University Animal Care and Use Committee, which has adopted animal care and use guidelines governing all animals used in experimental procedures. An autumn experiment used feather-sexable male and female broiler chickens (Arbor Acres) placed at 0.098 m2 per bird on litter-covered floor pens (40 per pen) or at 0.058 m2 per bird in cages (40 per cage) in the cage facility [6]. Males and females were reared separately in this experiment. The diets were supplemented with two selenium sources: NaSe or OR (Sel Plex 50) [7] at a Se concentratioan of 0.2 mg/kg of feed for each of these two Se forms. Brooding temperature and light management within the Broilermatic Cage System [8] and the conventional houses were consistent with current broiler management practices [1]. Brooding temperature in the cage facility and at litter level in the conventional house was 95°F (35°C), and this temperature was decreased incrementally (4°C at a time) to 70°F (20°C) by the time the birds were 21 d old. The photoperiod was established at 23 hr light and 1 hr darkness. The litter in the conventional broiler house consisted of pine wood shavings top-dressed over built-up litter. The experimental diets consisted of the North Carolina Agricultural Research Service Starter diet [3,177 kcal/kg ME, 22.5% CP (1 to 16 d of age)], grower diet [3,168 kcal/kg, 19.5% CP (16 to 35 d of age], and finisher diet [3,160 kcal/kg, 17.5% CP (35 to 42 d of age)]. Vitamin E was supplied at 33 IU/kg of diet. Body weights and feed conversions (FCR) were determined at 21 and 42 d of age (42d data are presented here), and mortality was recorded on a daily basis. Scores of feather tracts on the back (interscapsular cape, dorsal, pelvic, dorsal caudal tracts combined), breast (pectoral and sternal tracts combined), thigh (femoral tract- rear body and lower thigh, combined), neck (dorsal cervical and ventral cervical combined), tail (greater and lesser sickle feathers),

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TABLE 1. Effect of housing and Se form [NaSe vs. Se yeast as Sel Plex 50] [7] on performance of broiler chickens at 41 d of age HOUSING ENVIRONMENT Broilermatic

B

SE FORM NaSe Se yeast

House mean Conventional House mean

NaSe Se yeast

BW, kg

FCR,A g feed/g gain

MORTALITY, %

a

2.02 2.00a

b

1.750 1.760b

2.18a 2.57a

2.01x

1.755x

2.38x

1.99a 1.99a

2.031a 2.039a

1.83a 2.14a

1.99x

2.035y

1.99x

FCR = feed conversion ratio. Farmer Automatic Co. In a column, means with unlike superscripts differ significantly (P ≤ 0.05).

A B

NaSe or OR. In males, back feathering was very slow in comparison with females (Figure 2). However, there was a significant Se yeast effect associated with faster back feathering in males from 21 through 42 d of age. Full back feathering in males with OR supplementation was evident at 42 d, but males given NaSe were not fully back-feathered even at 42 d of age. Breast feathering was slower than back feathering (Figure 3). The slower feathering rate on this body surface, possibly, may be related to the fact that the birds spend a great deal of their time resting on sternal feathers and may actually suffer a feather loss on this region because of increased contact with the cage or litter floor. Pectoral feathering, which was not scored separately, developed rapidly in females and in many males. There was, however, an OR induc-

tion of faster feathering in both males and females (except at 28 d of age) when comparisons were made with the NaSe effect on feathering. However, breast feathering, even with OR, was still slower in males than in females. Thigh feathering was slower than back feathering, but faster than breast feathering, in both males and females (Figure 4). Nevertheless, OR in both males (except at 14 d of age) and females was associated with more rapid thigh feathering than was NaSe through 42 d of age. The lower thigh tracts feathered more rapidly than did the rear body tracts, and the independent temporal feathering of these tracts also appeared to be enhanced by the OR. Feathering of the wings was faster in ORtreated females and males than in conspecifics given NaSe (Figure 5). This increased feathering

FIGURE 1. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean whole body feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

FIGURE 2. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean back feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

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a,b; x,y

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FIGURE 5. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean wing feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

rate was evident at 21 d of age and persisted through 42 d of age. As seen in other regions of the body surface, females feathered their wings faster than did males. However, no information about primary feather development as influenced by selenoaminoacids was obtained in this study. Neck feathering was delayed until 21 d of age in both males and females when the first growth of feathers in this region became evident (Figure 6). Females feathered the neck faster than did males. At 21 d of age, the females showed significantly increased neck feathering, but from 28 through 42 d of age, there were no differences between feathering rates of NaSeand OR-supplemented birds (Figure 6). By 35 d of age, neck feathering was nearly complete

in the females, but at 42 d of age, the males had not attained complete neck feathering. Tail feathering rates in females (Figure 7) was stimulated by OR as early as 14 d of age and persisted through 42 d of age. Tail feathering in females was significantly faster than feathering of the tail in the males (Figure 7). Even though feathering in the males was significantly slower in males than females, there was still a significant stimulation of feather growth at 21 and 28 d of age in the males given OR. There was also a significant housing effect on feathering rate. Generally, whole body feathering was stimulated more by OR in females reared in the conventional broiler house (Figure 8). Even in females given NaSe, there was an

FIGURE 4. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean thigh feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

FIGURE 6. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean neck feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

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FIGURE 3. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean breast feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

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increase in feathering rate in those birds in the conventional house compared with those in the cage house. It has been reported that feathering on broilers in cages appeared to be negatively influenced [4, 5]. In males, OR caused a faster feathering rate than did the NaSe (Figure 9). A difference between conventional and cage rearing in feathering rate was not evident until 35 d of age when cockerels in the conventional house showed a feathering advantage that persisted through 42 d of age. Overall, whole body feathering was fastest in the conventional house in birds given OR. Smith [10] suggested that, in the future, broilers would be produced in cages. From the

FIGURE 8. Effect of cage and conventional rearing and Se source [NaSe and organic Se as Sel Plex 50 (SP50)] [7] on mean whole body feathering in female broiler chickens. Unlike lower case letters above the SP50Female columns indicates a significant difference (P ≤ 0.05) among NaSe- and SP50-associated feather scores in females in either the cage or conventional housing systems.

FIGURE 9. Effect of cage and conventional rearing and Se source [NaSe and organic Se as Sel Plex 50 (SP50)] [7] on mean whole body feathering in male broiler chickens. Unlike lower case letters above the SP50Male columns indicates a significant difference (P ≤ 0.05) among NaSe- and SP50-associated feather scores in males in either the cage or conventional housing systems.

mid 1960s to the early 1980s, many attempts were made to design cage facilities for the rearing of broiler chickens from hatch to market age. Unfortunately, none of these early cage systems allowed economical broiler production because there were high incidences of down grades [11]; breast blisters [12]; soft, distorted, and broken bones [13]; poor feathering [4, 5]; and overall poor performance [4, 5, 12]. The primary cause for lack of success in rearing broilers in cages was due in part to the lack of proper materials for the development of cages [10]. The cage rearing system, Broilermatic Cage System, used in this study appeared to have eliminated many of the early problems associated with cage rearing of broilers [6]. This caging system has gained popularity around the world, but many questions have been raised concerning production and performance of broilers reared in the system. The mechanism associated with increased feathering rates of broiler chickens reared in cages or in a conventional environment and fed diets supplemented with OR has not been established. In an earlier report [1], it was suggested that OR was more readily available for incorporation into the keratin used predominantly in feather growth. Evidence is available to show that there is a significant amount of Se incorporated in the feather [14]. Selenium cation incorporation into feathers is a possibility, but given the fact that Se easily substitutes for S in methionine and cysteine [15], one has to make the

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FIGURE 7. Effect of NaSe and organic Se [Sel Plex 50 (SP50)] [7] on mean tail feathering in broiler chickens. The asterisk (*) above the SP50-Female or SP50-Male columns indicates a significant difference (P ≤ 0.05) between NaSe- and SP50-associated feather scores within female and male groups.

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Selenium is a structural component of the glutathione peroxidase system, which acts as an antioxidant, decreasing numbers of intracellular reactive oxygen metabolites [24]. For Se to be effective in the activation of this enzyme system, the NaSe and selenate forms must be converted to the selenide form before selenoproteins are synthesized. Cysteine must combine with selenide to form selenocysteine via a tRNA-mediated process, and this is a very limiting process in mammals [17]. Selenocysteine then serves as the active precursor of selenoproteins, including glutathione peroxidase. Therefore, it is possible that the improved feathering rate in broilers supplemented with Se yeast may be related to improved antioxidant activity, but this remains to be elucidated. The improved feathering rate in broilers, especially in the slow-feathering males, suggested that Se yeast might be modifying gene action. Slow feathering is regulated by a dominant sexlinked K gene whereas the k+ recessive allele regulates rapid feathering found in females. The slow-feathering K gene is expressed in feathersexable male broiler chickens and the slowfeathering trait in these birds is evident for several weeks after hatch. The slow feathering trait in broilers apparently does not affect performance in well-maintained flocks [25, 26, 27]. Therefore, the supplementation of Se yeast, a more active form of Se than NaSe, may suppress the expression of the K gene product or it may be facilitating the k+ gene product, allowing the birds to show more rapid feathering. If this is the case, Se from the OR source could also be affecting the expression of other genes. Additional studies are required to elucidate the mode of action of Se yeast on feathering rates in poultry.

CONCLUSIONS AND APPLICATIONS 1. Organic Se from Sel Plex 50 improved feathering rate in feather-sexable, slow-feathering broiler males and in normal-feathering broiler females. 2. Improved feathering had no significant effects on BW or FCR at 42 d of age. 3. The data suggest that organic Se-fed broilers might have been more metabolically efficient than those broilers fed sodium selenite. 4. Use of Se-substituted amino acids may induce more rapid feathering by affecting gene expression, especially in the slow-feathering male broiler.

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assumption that the feather Se source may be from selenomethionine and selenocysteine [16, 17]. A proximate analysis of feather proteins revealed that the overall contribution of methionine, cystine, and cysteine was relatively low in relation to the total amino acid content [18]. Thus, if the S amino acids were low or even marginally deficient in the diets of chickens, the result could be slow and incomplete feathering. However, selenomethionine is readily utilized as a substrate by enzymes that use methionine, and selenomethionine may be more available than pure methionine [15]. It has been reported that organic Se as selenomethionine was absorbed more efficiently and was retained better than selenite as a source for intracellular selenium [19]. Furthermore, OR is equivalent or even superior to NaSe in terms of gut absorption [20] and in the prevention of pancreatic fibrosis [21]. Improvement in feathering rate with OR was observed as early as 21 d of age, and this improvement was evident through 42 d of age. These data suggest that the improved feathering was directly related to the improved retention of Se yeast and that selenoaminoacids such as selenomethionine or selenocysteine from OR were used for keratin synthesis in feather production, sparing the cysteine pool in liver and muscle glutathione, which is normally used [22, 23]. Because organic Se is retained in tissues to a greater degree than is NaSe-based Se [19, 20, 21], it stands to reason that during times when there is a demand for feather synthesis, Se yeast would be a better source of Se than NaSe. The OR feed supplementation was reported to facilitate better feathering rates during both cool and hot seasons in slow-feathering males [1], and, currently, we find that not only males but females feathered better when they were fed OR.

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5. Improved feathering should result in fewer down grades in broilers due to skin abrasions, lacerations, and bruises.

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16. Cummins, L.M., and J.L. Martin, 1967. Are selenocystine and selenomethionine synthesized in vivo from sodium selenite in mammals? Biochemistry 6:3162–3168.

2. Thompson, J.N., and M.L. Scott, 1969. Role of selenium in the nutrition of the chick. J. Nutr. 97:335–342.

17. Esaki, N., H. Tanaka, S. Uemura, T. Suzuki, and K. Soda, 1979. Catalytic action of L.-methionine-γ-lyase on selenomethionine and selenols. Biochemistry 19:407–410.

3. Supplee, W.C., 1966. Feather abnormality in poults fed a diet deficient in vitamin E and selenium. Poult. Sci. 45:852–854. 4. Andrews, L.D., G.S. Nelson, G.C. Harris, Jr., and T.L. Goodwin, 1975. Performance of five strains of broilers in a four tier cage system with plastic floors. Poult. Sci. 54:54–58.

6. Broilermatic Cage System; Farmer Automatic, Co., Register, GA 30452. 7. Alltech, Inc., Nicholasville, KY 40356. 8. Havenstein, G.B., J.L. Grimes, P.R. Ferket, C.R. Parkhurst, F.W. Edens, J. Brake, and J.H. van Middelkoop, 1998. Recent experiences with reduced or non-litter systems for growing broilers and turkeys. Pages 225–240 in: Proc. 1998 Natl. Poult. Waste Manage. Symp., Springdale, AR. 9. SAS Institute, 1994. SAS User’s Guide: Statistics. SAS Institute, Cary, NC. 10. Smith, W.M., 1972. Whither cages in broilers? Poult. Digest 31:76–77. 11. Lloyd, R.W., 1969. Growing broilers in cages. Poult. Digest 28:542–545. 12. Andrews, L.D., and T.L. Goodwin, 1973. Performance of broilers in cages. Poult. Sci. 52:723–728. 13. Merkley, J.W., 1976. Increased bone strength in coop-reared broilers provided fluoridated water. Poult. Sci. 55:1313–1319. 14. Goede, A.A., and M. Bruin, 1984. The use of bird feather parts as a monitor for metal pollution. Environ. Poll. (Ser. B) 8:281–298. 15. Markham, G.D., E.W. Hafner, C.W. Tabor, and H. Tabor, 1980. S-adenosylmethionine synthetase from Escherichis coli. J. Biol. Chem. 255:9082–9092.

19. Shan, A.S., and R.H. Davis, 1994. Effect of dietary phytate on growth and selenium status of chicks fed selenite or selenomethionine. Br. Poult. Sci. 35:725–741. 20. Collins, V.C., A.H. Cantor, M.J. Ford, and M.L. Straw, 1993. Bioavailability of selenium in selenized yeast for broiler chickens. Poult. Sci. 72(Suppl. 1):85. 21. Cantor, A.H., M.L. Langevin, T. Naguchi, and M.L. Scott, 1975. Efficacy of selenium in selenium compounds and feedstuffs for prevention of pancreatic fibrosis in chicks. J. Nutr. 105:106–111. 22. Goto, I., and S. Okamoto, 1965. Blood reduced glutathione levels and plasma protein constituents in molting hens. Jpn. Poult. Sci. 2:33–36. 23. Murphy, M.E., and J.R. King, 1985. Diurnal variation in liver and muscle glutathione pools of molting and nonmolting whitecrown sparrows. Physiol. Zool. 58:646–654. 24. Tappel, A.L., 1987. Glutathione peroxidase and other selenoproteins. Pages 122–132 in: Selenium in Biology and Medicine. G.F. Combs, Jr., O.A. Levander, J.E. Spallholz, and J.E. Oldfield, ed. Van Nostrand Reinhold Co., New York, NY. 25. Dunnington, E.A., and P.B. Siegel, 1986. Sex-linked feathering alleles (K, K+) in chicks of diverse genetic backgrounds. 1. Body temperatures and body weights. Poult. Sci. 65:209–214. 26. Lowe, P.C., and J.W. Merkley, 1986. Association rate of feathering genotypes in broilers with production and carcass composition traits. 1. Effect of genotypes, sex, and diet on growth and feed conversion. Poult. Sci. 65:1853–1858. 27. Merkley, J.W., and P.C. Lowe, 1988. Association rate of feathering genotypes in broilers with production and carcass composition traits. 2. Effect of genotypes and diet on processing traits and lipid deposition. Poult. Sci. 67:914–919.

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5. Bayer, R.C., F.V. Muir, C.B. Chawan, and A.T. Bryan, 1976. Infected feather follicles in cage reared broilers. Poult. Sci. 55:1194–1200.

18. Harrap, B.S., and E.F. Woods, 1964. Soluble derivatives of feather keratin. Biochem. J. 92:8–18.