Increasing Dietary Energy with Starch and Soluble Fibre and Reducing ADF at Different Protein Levels for Growing Rabbits

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1 ORIGINAL SCIENTIFIC PAPER 235 Incresing Dietry Energy with Strch nd Soluble Fibre nd Reducing ADF t Different Protein Levels for Growing Rbbits Mrco TAZZOLI 1 Mrco BIROLO 1 Eirini FILIOU 1 Angel TROCINO 2 ( ) Andre ZUFFELLATO 3 Gerolmo XICCATO 1 Summry The effect of incresing dietry energy by incresing both strch (14% to 20%) nd soluble fibre (9.6% to 11.6%) nd decresing ADF content (21% to 13%) t two crude protein levels (14% nd 15%) ws ssessed on helth, growth performnce, cecl fermenttive ctivity, gut mucos trits, nd crcss nd met qulity of growing rbbits rered from 34 to 76 dys of ge. At wening, 306 rbbits were divided into six groups nd fed d libitum six diets formulted ccording to bi-fctoril rrngement with 3 (strch+soluble fibre)/adf rtio (L=1.2; M=1.8; H=2.8) x 2 protein levels. The contemporry increse of dietry strch nd soluble fibre nd the reduction of ADF linerly incresed the digestibility of dry mtter, energy nd ll nutrients, decresed feed intke nd improved feed conversion (3.65 to 2.76 in rbbits fed diets L nd H; P<0.001); it incresed morbidity (P=0.09) but did not ffect mortlity due to epizootic rbbit enteropthy; t cecum, VFA production rised (52.1 to 61.9 mmol/l) nd ph (5.90 to 5.67) nd N mmoni lowered (4.85 to 1.93 mmol/l); the villi/crypts rtio (4.42 vs nd 3.95 in rbbits fed diets L, M nd H) decresed in non liner mode. The decrese of the protein level did not ffect growth performnce, but nerly hlved mortlity (28.9% vs. 16.3%; P=0.01) nd incresed cecl ph (5.70 to 5.87; P=0.05). Wek effects of the dietry tretments were mesured on crcss trits nd met qulity. Key words strch, soluble fibre, insoluble fibre, protein, growing rbbits 1 Deprtment of Agronomy, Food, Nturl Resources, Animl nd Environment, University of Pdov, Agripolis, I Legnro, Pdov, Itly 2 Deprtment of Comprtive Biomedicine nd Food Science, University of Pdov, Agripolis, I Legnro, Pdov, Itly e-mil: ngel.trocino@unipd.it 3 Veronesi Veron S.p.A., I-37142, Quinto di Vlpnten, Veron, Itly Received: April 23, 2013 Accepted: June 26, 2013 ACKNOWLEDGEMENTS This study ws funded by the University of Pdov, Itly (2011 CPDA119830). Agriculture Conspectus Scientificus. Vol. 78 (2013) No. 3 ( )

2 236 Mrco TAZZOLI, Mrco BIROLO, Eirini FILIOU, Angel TROCINO, Andre ZUFFELLATO, Gerolmo XICCATO Aim The present study imed t evluting whether the increse of dietry energy obtined by contemporry increment of strch (14% to 20%) nd soluble fibre (9.6% to 11.6%) concentrtion t the expense of ADF supply (21% to 13%) nd the vrition of protein level (14% to 15%) cn ffect helth sttus, growth performnce, digestive efficiency, cecl fermenttion ctivity nd gut mucos trits, nd crcss nd met qulity in growing rbbits. Mteril nd methods A totl of 306 wened Hyplus crossbred rbbits (Hyphrm, Groupe Grimud, Roussy, Frnce) of both genders were put in individul cges (285 x 410 x 285 mm) t 34 d of ge, divided into six groups (51 rbbits ech), homogeneous in verge live weight nd vribility, nd given d libitum ccess to six experimentl pelleted diets until slughter (76 d of ge). The diets (L14, M14, H14, L15, M15 nd H15) were formulted s combintion of three (strch+soluble fibre)/adf rtios (low, L=1.2; moderte, M=1.8; high, H=2.8) combined with two crude protein levels (14% nd 15%) (Tble 1). No ntibiotics or drugs were included in the feed. Individul live weight nd feed intke were recorded three times week. Helth sttus ws controlled dily. Epizootic rbbit enteropthy (ERE) occurred soon fter one week of tril nd ll rbbits were treted with ntibiotics in wter (timulin nd colistin) from 48 to 57 dys of ge. At 42 d of ge, 36 rbbits (6 per diet) out of the 306 initil rbbits were slughtered to smple cecl content nd gut mucos (jejunum nd ileum). The digestibility coefficients nd digestible energy (DE) concentrtion of the experimentl diets were mesured in vivo on 72 rbbits mong those on tril (12 nimls per diet) from 49 to 52 dys of ge ccording to Perez et l. (1995). Diets, feces, cecl contents nd gut mucos were nlyzed ccording to the methods detiled by Trocino et l. (2013). The soluble fibre content ws obtined by subtrcting NDF fter correction for sh nd protein from TDF (Trocino et l., 2013b). At 76 d of ge, 120 rbbits were selected (20 nimls per diet) representtive in terms of verge weight nd vribility nd slughtered. After 24 h of cooling t 4 C, the crcsses were dissected ccording to the interntionl scientific protocols (Blsco et l., 1993). The dt of performnce, digestibility coefficients, intestinl mucos trits nd cecl fermenttion ctivity were submitted to ANOVA with (strch+soluble fibre)/adf rtio, protein level nd their interction s min fctors nd using the GLM procedure of SAS (SAS Institute, Cry, NC, USA). Orthogonl contrsts were used to test the liner nd qudrtic response to the increse of the (strch+soluble fibre)/adf rtio. Mortlity, morbidity, nd snitry risk (i.e., mortlity+morbidity) were nlysed by the CATMOD procedure of SAS. Results nd discussion Despite the occurrence of ERE which severely ffected rbbits during the first weeks on tril (verge mortlity: 22.6%), nimls recovered well thnks to the ntibiotic tretment nd showed stisfying performnce for the genetic type used: rbbits weighed on verge 2831 g t 76 dys of ge, with dily weight gin of 44.1 g/d, feed intke of 141 g/d nd feed conversion of 3.21 in the whole period of growth. As the interctions were not significnt, the results re presented nd discussed ccording to the min fctors. Effect of (strch+soluble fibre)/adf rtio When the rtio incresed from 1.2 to 1.8 to 2.8, the digestibility of energy nd ll nutrients linerly rised (Tble 2), especilly fibre frctions with the exception of soluble fibre (85-90%); therefore the DE concentrtion incresed from 9.7 to 11.0 to 12.2 MJ/kg (Tble 1); growth rte did not chnge (Tble 3) but feed intke linerly decresed (P<0.001) both in the first nd second period of the Tble 1. Ingredients (%), chemicl composition nd nutritive vlue of the experimentl diets Diet L14 M14 H14 L15 M15 H15 Ingredients Dehydrted lflf mel 16% CP Whet brn Brley Dried beet pulp Soyben mel 50% CP Sunflower oil Other ingredients Chemicl composition Dry mtter, % Crude protein, % Ether extrct, % TDF, % NDF, % ADF, % ADL, % Soluble fibre, % Strch, % Digestible energy (DE), MJ/kg Digestible protein/de, g/mj Molsses, limestone, diclcium phosphte, slt, L-lysine, DL-methionine, DL-threonine, vitmin-minerl premix.

3 Incresing Dietry Energy with Strch nd Soluble Fibre nd Reducing ADF t Different Protein Levels for Growing Rbbits 237 Tble 2. Digestibility coefficients (%) (Strch+soluble fibre)/adf rtio Protein level RSD Rbbits, n Dry mtter < Crude protein < < Ether extrct <0.001 < < TDF < NDF < ADF < Soluble fibre < Strch < Gross energy < Residul stndrd devition. b Liner component of vrince. c Qudrtic component of vrince. Tble 3. Performnce nd helth sttus from 34 d until 76 d of ge (Strch+soluble fibre)/adf rtio Protein level RSD Rbbits, n Live weight, g At 34 d At 55 d At 76 d First period (34-55 d) Dily weight gin, g/d Feed intke, g/d < Feed conversion < Second period (55-76 d) Dily weight gin, g/d Feed intke, g/d < Feed conversion < Whole tril (34-76 d) Dily weight gin, g/d Feed intke, g/d < Feed conversion < Helth sttus d Mortlity, % Morbidity, % Snitry risk e, % Residul stndrd devition. b Liner component of vrince. c Qudrtic component of vrince. d Probbility of χ 2 -test. e Mortlity + morbidity. tril nd, s consequence, feed conversion improved (P<0.001). The improvement of feed conversion in diets with higher DE obtined incresing strch nd soluble fibre in replcement of insoluble fibre ws expected (Bls nd Gidenne, 2010; Trocino et l., 2013b), wheres the consequences on helth sttus were less obvious. A higher morbidity ws observed in rbbits fed the highest (strch+soluble fibre)/adf rtio (from 17.8 nd 20.0% to 31.1%; P=0.09), but mortlity ws not modified (Tble 3). As reviewed by Bls nd Gidenne (2010), helth of rbbits my impir when strch is incresed t the expense of insoluble fibre, while positive effects my be recorded when soluble fibre replces insoluble fibre, especilly in presence of ERE (Xiccto et l., 2006; Gómez-Conde et l., 2007; Mrtínez-Vllespín et l., 2011). In the present tril, the increse of soluble fibre likely counterblnced the negtive effects on helth of incresing strch nd decresing ADF, therefore permitting to use high energy diets without consequences. With the increse of the (strch+soluble fibre)/adf rtio, VFA production t cecum linerly incresed nd ph vlue nd N-mmoni decresed; the proportion of cetic cid tended to rise nd tht of propionic cid to decrese (Tble 4). The mjor vilbility of fermentble crbohydrtes, both s strch nd soluble fibre, promoted cecl VFA production nd reduced N-mmoni levels (Jehl nd Gidenne, 1996; Bls nd Gidenne, 2010; Trocino et l., 2013b), nd likely modified cecl microflor, in rbbits fed higher dietry (strch+soluble fibre)/adf rtio. However, s demonstrted by the higher digestibility, lso insoluble fibre my hve been more susceptible to microflor fermenttion in the cecum, becuse of the lower lignifiction nd complexity of the cell wlls or different hemicellulosic constituents (Crbño et l., 2001; Grcí et l., 2002). Previous studies correlted improvements in helth sttus with better brrier function of the intestinl mucos in rbbits fed higher levels of the most soluble fibre frctions (from 7 to 12%) t the

4 238 Mrco TAZZOLI, Mrco BIROLO, Eirini FILIOU, Angel TROCINO, Andre ZUFFELLATO, Gerolmo XICCATO Tble 4. Cecl content nd intestinl mucos trits (Strch+soluble fibre)/adf rtio Protein level RSD Cecl content ph N-NH3, mmol/l < Totl VFA, mmol/l C2, % mol C3, % mol C4, % mol C5, % mol C3/C4 rtio Jejunum mucos Villi height d, μm < Crypts depth, μm Villi/crypts Ileum mucos Villi height, μm Crypts depth, μm Villi/crypts Residul stndrd devition. b Liner component of vrince. c Qudrtic component of vrince. d Villi height: 867, 758, 715, 811, 706 nd 786 μm in rbbits fed diets L14, M14, H14, L15, M15, H15; probbility of R x P interction = Tble 5. Results t commercil slughter nd crcss qulity (Strch+soluble fibre)/adf rtio Protein level RSD Slughter weight (SW) d, g Gut incidence e, %SW Chilled crcss (CC), g Dressing out, %SW Reference crcss (RC) f, g Dissectible ft, %RC Hind legs, %RC Hind leg muscle/bone rtio Residul stndrd devition. b Liner component of vrince. c Qudrtic component of vrince. d Live weight immeditely before slughter; e Incidence of the full gstro-intestinl trct. f Chilled crcss without hed, liver, thorcic orgns nd kidneys. expense of insoluble fibre (Álvrez et l., 2007; Gómez-Conde et l., 2007). However, this ws not our cse, since villi height nd villi/crypt rtio of jejunum decresed, which should be rther considered negtively (Tble 4). On the other hnd, the ileum mucos morphology ws not ffected by dietry tretments, s lso found in other studies of ours (Xiccto et l., 2008; Trocino et l., 2010, 2011). The effect of the experimentl fctors ws hrdly mesurble on slughter results (Tble 5), prt from significnt nd qudrtic chnge of the hind leg muscle to bone rtio (P=0.01) which indictes tht diets with n intermedite (strch+soluble fibre)/adf rtio re probbly the most equilibrte nd cpble of stimulting the highest musculr growth of rbbits. Effect of crude protein level The decrese of dietry crude protein (CP) from 15% to 14% s-fed lowered CP digestibility (Tble 2), likely becuse of the higher protein rte derived from lflf mel rther thn soyben mel; besides, lower digestibility vlues were recorded for soluble fibre. Quite surprisingly, limited decrement of dietry CP nerly hlved the mortlity rte (16.3% vs. 28.9%, P=0.01). On the other hnd, it did not ffect productive performnce in the whole period, even if feed conversion tended to lower during the first period of tril nd growth nd feed intke decresed during the second period (Tble 3). In fct, if 15% s-fed of dietry CP usully covers protein requirements for growing rbbits (de Bls nd Mteos, 2010), the supply of min limiting mino cids (lysine, methionine nd threonine) my permit reduction until or below 14% (Trocino et l., 2000; Grcí-Plomres et l., 2006). A higher dietry protein lowered cecl ph (5.87 to 5.70) (Tble 4), wheres ll microbil popultions benefit from high protein content in the cecum for their development nd prolifertion. However, some pthogenic strins of E. coli nd Clostridi spp. my be t n dvntge when there is n excess of protein (Grcí-Plomres et l., 2006; Chmorro et l., 2007; Crbño et l., 2009). In fct, Mrtínez-Vllespín et l. (2011) found tht reducing dietry protein from 17.5 to 14.5% lowered mortlity ( 19.9 percentge points) of rbbits ffected by ERE during post-wening period (28-49 d of ge), s we observed in the present tril.

5 Incresing Dietry Energy with Strch nd Soluble Fibre nd Reducing ADF t Different Protein Levels for Growing Rbbits 239 Conclusions On the bsis of the results bove, the contemporry increse of strch (until 20%) nd soluble fibre (until 12%) hd positive effects on digestive physiology, weight gin nd feed efficiency of rbbits without impiring crcss trits or met qulity. However, in presence of epizootic rbbit enteropthy, the contemporry decrese of ADF below 13% might negtively ffect digestive helth of growing rbbits, by provoking higher morbidity. Lowering the protein level from 15% to 14% hd scrce effects on growth performnce but reduced the susceptibility to digestive diseses. References Álvrez J.L., Mrgüend I., Grcí-Rebollr P., Crbño R., De Bls J.C., Corujo A., Grcí-Ruiz A.I. (2007). Effects of type nd level of fibre on digestive physiology nd performnce in reproducing nd growing rbbits. World Rbbit Sci. 15: Bls E., Gidenne T. (2010). Digestion of sugrs nd strch. In: Nutrition of the Rbbit, 2 nd edition (C. de Bls, J. Wisemn, eds), CABI Publishing, Wllingford, UK, Blsco A., Ouhyoun J., Msoero G. (1993). Hrmoniztion of criteri nd terminology in rbbit met reserch. World Rbbit Sci. 1: Crbño R., Grcí J., de Bls J.C. (2001). Effect of fibre source on ilel pprent digestibility of non-strch polyscchrides in rbbits. Anim. Sci. 72: Crbño R., Villmide M.J., Grcí J., Nicodemus N., Llorente A., Chmorro S., Menoyo D., Grcí-Rebollr P., Grcí-Ruiz A.I., de Bls J.C., (2009). New concepts nd objectives for proteinmino cid nutrition in rbbits. A review. World Rbbit Sci. 17: Chmorro S., Gómez-Conde M.S., Pérez de Rozs A.M., Bdiol I., Crbño R., De Bls J.C. (2007). Effect on digestion nd performnce of dietry protein content nd of incresed substitution of lucerne hy with soy-ben protein concentrte in strter diets for young rbbits. Animl 1: Grcí J., Gidenne T., Flco-e-Cunh L., de Bls C. (2002). Identifiction of the min fctors tht influence cecl fermenttion trits in growing rbbits. Anim. Res. 51: Grcí-Plomres J., Crbño R., Grcí-Rebollr P., de Bls J.C., Corujo A., Grcí-Ruiz A.I. (2006). Effects of dietry protein reduction nd enzyme supplementtion on growth performnce in the fttening period. World Rbbit Sci. 14: Gómez-Conde M.S., Grcí J., Chmorro S., Eirs P., Rebollr P.G., Pérez de Rozs A., Bdiol I., de Bls C., Crbño R. (2007). Neutrl detergent-soluble fiber improves gut brrier function in twenty-five-dy-old wened rbbits. J. Anim. Sci. 85: Jehl N., Gidenne T. (1996). Replcement of strch by digestible fibre in feed for the growing rbbit. 2. Consequences for microbil ctivity in the cecum nd on incidence of digestive disorders. Anim. Feed Sci. Technol. 61: Mrtínez-Vllespín B., Mrtínez-Predes E., Ródens L., Cerver C., Pscul J.J., Bls E. (2011). Combined feeding of rbbit femle nd young: Prtil replcement of strch with cid detergent fibre or/nd neutrl detergent soluble fibre t two protein levels. Livest. Sci. 141: Perez J.M., Lebs F., Gidenne T., Mertens L., Xiccto G., Prigi Bini R., Dlle Zotte A., Cossu M.E., Crzzolo A., Villmide M.J., Crbño R., Frg M.J., Rmos M.A., Cerver C., Bls E., Fernández J., Flco E. Cunh L., Bengl Freire J. (1995). Europen reference method for in vivo determintion of diet digestibility in rbbits. World Rbbit Sci. 3: Trocino A., Xiccto G., Srtori A., Queque P.I. (2000). Feeding plns t different protein levels: effects on growth performnce, met qulity nd nitrogen excretion in rbbits. World Rbbit Sci. 8 (suppl. 1): Trocino A., Frgkidkis M., Rdelli G., Xiccto G. (2010). Effect of dietry soluble fibre level nd protein source on growth, digestion, cecl ctivity nd helth of fttening rbbits. World Rbbit Sci. 18: Trocino A., Frgkidkis M., Mjolini D., Crbño R., Xiccto G. (2011). Effect of the increse of dietry strch nd soluble fibre on digestive efficiency nd growth performnce of met rbbits. Anim. Feed Sci. Technol. 165: Trocino A., Frgkidkis M., Mjolini D., Tzzoli M., Rdelli G., Xiccto G. (2013). Soluble fibre, strch nd protein level in diets for growing rbbits: Effects on digestive efficiency nd productive trits. Anim. Feed Sci. Technol. 180: Trocino A., Grcí J., Crbño R., Xiccto G. (2013b). A metnlysis on the role of soluble fibre in diets for growing rbbits: review. World Rbbit Sci. 21: Xiccto G., Trocino A., Crrro L., Frgkidkis M. (2006). Digestible fibre to ADF rtio nd protein concentrtion in diets for erly-wened rbbits. In: Proc 3 rd Rbbit Congress of Americ, Mringá, Brsil, Comm. 35, pp Xiccto G., Trocino A., Crrro L., Frgkidkis M., Mjolini D. (2008). Digestible fibre to strch rtio nd ntibiotic tretment time in growing rbbits ffected by epizootic rbbit enteropthy. In: Proc 9 th World Rbbit Congress, Veron, Itly, pp cs78_39