Soybean Hulls as an Alternative Feed for Horses

Transcription

1 Animl Industry Report AS 650 ASL R Soyben Hulls s n Alterntive Feed for Horses Josie Booth Iow Stte University Howrd Tyler Iow Stte University Peggy Miller-Auwerd Iow Stte University Jenette Moore North Crolin Stte University Recommended Cittion Booth, Josie; Tyler, Howrd; Miller-Auwerd, Peggy; nd Moore, Jenette (2004) "Soyben Hulls s n Alterntive Feed for Horses," Animl Industry Report: AS 650, ASL R1931. DOI: Avilble t: This is brought to you for free nd open ccess by the Animl Science Reserch Reports t Iow Stte University Digitl Repository. It hs been ccepted for inclusion in Animl Industry Report by n uthorized editor of Iow Stte University Digitl Repository. For more informtion, plese contct digirep@istte.edu.

2 Soyben Hulls s n Alterntive Feed for Horses A.S. Leflet R1931 Josie Booth, Grdute Reserch Assistnt Howrd Tyler, Associte Professor Peggy Miller-Auwerd, Associte Professor, Iow Stte University nd Jenette Moore, North Crolin Stte University, Rleigh Summry nd Implictions Soyben hulls (SH) hve been successfully fed to ruminnt nimls s n economicl substitute for hy. This feedstuff is source of highly digestible fiber nd does not contin strch. The purpose of this tril ws to evlute SH s replcement fiber in horse diets. Four ceclly cnnulted Qurter Horse geldings, ged 6 to 10 yers nd verging 502 kg, were used in 4x4 Ltin Squre design with 21-dy periods. Diets consisted of lflf-bromegrss hy (14.4% CP, 58.1% NDF, 39.1% ADF) with the ddition of either 0, 25, 50, or 75% unpelleted SH (13.1% CP, 60.6% NDF, 43.7% ADF). Diets were offered t 2% of bodyweight (s fed) dily nd body weights were mesured weekly. Cecl smples (90-min post-feeding) nd totl fecl collections (3 d) were tken t the end of ech tretment period. Fecl collection bgs were emptied every 6 hours nd 10% of the totl mount ws frozen for lter nlysis. Totl cecl VFA production incresed linerly from 70 mm to 109 mm s proportions of SH in diets incresed (P = 0.02). Proportions of propionte incresed linerly (P < 0.01) nd cubiclly (P = 0.03) with mens of 15.7, 18.0, 16.6, nd 21.9 moles per 100 moles totl VFA for the 0, 25, 50, nd 75% SH diets respectively. Proportions of butyrte decresed linerly (P < 0.01) from 5.3 to 3.9 moles per 100 moles totl VFA. The cette to propionte rtio decresed linerly (P = 0.02) nd cubiclly (P = 0.03) with mens of 4.9, 4.2, 4.9, nd 3.3. Apprent digestibility of DM, OM, NDF, ADF, cellulose, nd hemicellulose did not differ (P > 0.24) with tretment. Apprent digestibility of N decresed linerly (P < 0.01) s concentrtions of SH incresed in the diet, most likely due to incresed cecl fermenttion nd microbil biomss production. Cecl ph decresed linerly (P = 0.01) from 7.00 to 6.45 s the level of SH incresed, but there ws no chnge (P liner = 0.68) for cecl mmoni (men concentrtion of 3.85 mm). Soyben hulls pper to stimulte cecl fermenttion nd to be suitble replcement for hy in equine diets. This my be n especilly importnt finding for owners of geritric horses tht often hve difficulty consuming roughges. Introduction Soyben hulls (soyhulls) my be dded to equine rtions s source of fiber. This by-product feed is source of highly digestible fiber. Due to thick cell wlls, most of the polyscchrides re found in the NDF frction of the plnt. The NDF frction of soyhulls contins lrge mounts of cellulose nd hemicellulose; however, it contins reltively little lignin, llowing extensive bcteril fermenttion. Soyhulls re high in pectins nd other soluble fibers, but they contin reltively little strch. Therefore soyhulls provide dequte energy without some of the common mngement problems ssocited with high grin diets in both ruminnt nimls nd horses. Due to the fibrous nture of the feedstuff, digestion of soyhulls occurs primrily in the cecum. Fiber in equine diets is importnt to mintin stble hindgut environment tht is less susceptible to cidosis. Soyhulls hve been successfully fed to ruminnt nimls s n economicl substitute for grin nd hy. Studies in beef cttle, met gots, nd diry cows report fvorble responses in the rumen environment when soyhulls re substituted for hy in their diets. The use of soyhulls in these diets lso incresed totl rumen VFA nd incresed digestibility of DM, OM, nd cell wlls. The purpose of this tril ws to evlute the use of soyhulls s replcement fiber source for the horse, specificlly evluting effects of this feedstuff on digestibility nd cecl environment. Procedures The Iow Stte University Animl Cre nd Use Committee pproved ll procedures used in this experiment. Horses nd Tretments. Ceclly fistulted Qurter Horse geldings (n = 4) from the Iow Stte University Horse Frm were utilized in 4x4 Ltin Squre design with 21-dy tretment periods. Horses rnged in ge from 6 to 10 yr nd body weight verged 502 kg. Tretments consisted of 4 diets contining lflfbromegrss hy with the inclusion of either 0, 25, 50, or 75% unpelleted soyhulls. Diets were offered t 2% of bodyweight (s-fed) dily. Body weight ws mesured weekly nd diets were djusted ccordingly throughout the tretment period. Horses were fed twice dily nd housed in individul stlls, receiving pproximtely 4 h of free exercise dily. Wter nd minerl sources were provided on n d libitum bsis. Vccintions nd deworming prctices were consistent with frm protocol. Smple Collection Cecl smples were collected on the first dy nd on d 17 of ech period. Smples were obtined pproximtely 90 min fter the morning feeding. The cnnul ws opened nd cecl contents (solid nd liquid) were collected in n insulted continer. Cecl smples were immeditely nlyzed for ph using Corning 314 hnd-held ph meter. Cecl fluid smples were then frozen until thwed for further nlysis t North Crolin Stte University.

3 Totl fecl collections were obtined for the lst 3 d of ech tretment period; collections begn on dys 18, 39, 60, nd 81 of the tril. During the 3-d collection period horses were fitted with fecl collection bgs nd housed individully in tie stlls. Fecl smples were removed from th bgs every 6 h. For ech 24 h, 10% subsmple of feces (by weight) ws collected, plced in individul bgs, nd frozen for lter nlysis. Smples of soyhulls, hy, nd diet refusls were lso obtined throughout the totl collection period nd stored for further nlysis. Chemicl Anlysis Hy, soyhull, diet refusl, nd fecl smples were nlyzed for DM, OM, nd Kjeldhl-N ccording to AOAC (1995) protocols. Crude protein ws clculted s percentge of Kjeldhl-N x All smples were nlyzed for NDF, ADF, cellulose, lignin, nd hemicellulose ccording to procedures described for use in n Ankom fiber pprtus. Cecl VFA concentrtions were determined by Vrion 3800 gs chromtogrph. The gs chromtogrph ws fitted with Nikol fused silic cpillry column (15 m; 0.53 mm i.d.; 0.5 µm film thickness; Supleco, Bellefonte, PA). Cecl mmoni concentrtions were determined vi colorimetric procedures used for Kjeldhl N. Sttisticl Anlysis Dt were nlyzed using the PROC GLM procedure of SAS. Dt from ll nimls were included in the nlysis. Liner, qudrtic, nd cubic effects were tested in the form of contrsts. In ll cses, probbilities less thn 0.05 were considered to be sttisticlly significnt. Probbility vlues between 0.05 nd 0.15 were considered to be trends towrds significnce. Results nd Discussion Diet Composition Composition of hy, soyhulls, nd diets used throughout the experiment re listed in Tble 1. Soyhulls utilized in this tril hd similr chemicl composition to published vlues (12.2% CP, 66.3% NDF, nd 49.0% ADF; NRC, 1989) indicting there ws little contmintion with soyben mel. Soyhulls re often vrible in composition, mking comprisons between trils difficult. The composition of hy used in this tril ws consistent with vlues typicl for medium-qulity grss-legume mix, nd chemicl composition of the hy ws comprble to the soyhull product with the exception tht soyhulls hd 70% less lignin. No helth problems were encountered during the tril. Unpelleted soyhulls re quite dusty, suggesting possible risks to respirtory helth. However, no pprent respirtory difficulties were encountered during this tril. There were lso no pprent difficulties with respect to gstrointestinl helth. Intke nd Body Weight Horses redily consumed the soyhulls with no significnt refusls of dietry tretments (Tble 2). Mesured intke of soyhulls s percentge of diet DM ws 97% of wht ws offered for the 25% soyhull diet nd 99% for the 50% soyhull diet; however, it ws only 93% for the 75% diet, indicting this level is t the upper end of wht is cceptble to horses. Digestibility Digestibilities of DM, OM, NDF, ADF, cellulose, nd hemicellulose did not differ (P > 0.25) with incresing inclusion rtes of soyhulls in the diet (Tble 3). Moore- Colyer et l. (2002) observed greter totl trct DM, OM, CP, ADF, nd NDF digestibility of SH when compred to hy cubes fed s the sole forge source. In tht tril, totl trct digestibility ws clculted using the mobile bg technique rther thn totl fecl collection, nd the hy cubes fed were of lower qulity (8.2% CP, 62.3% NDF, 35.4% ADF) thn the grss-legume hy fed in our tril. Digestibility lignin (P = 0.04) decresed s inclusion rtes of soyhulls incresed (Tble 3). Lignin is not source of nutrients nd is present in the feed in low mounts. Digestibility of N (P < 0.01) lso decresed s dietry SH level incresed (Tble 3). The decresed N digestibility is most likely due to incresed production of microbil biomss in the cecum; microbil N is lost in the feces becuse the cecum is beyond the site of protein digestion. The increse in VFA production (Tble 4) suggests n increse in microbil biomss occurred. This experiment demonstrted tht inclusion of soyhulls in forge-bsed diets for horses t limited intke does not influence the digestibility of DM, OM, NDF, nd ADF. This is different thn wht hs been found with ruminnt nimls. For exmple, increses in the digestibility of NDF, ADF, N, OM, nd DM is observed in the diets of gots s proportions of soyhulls in diets incresed. Cecl Fluid Totl cecl VFA (P < 0.02) production incresed s proportions of soyhulls in diets incresed (Tble 4). This suggests tht soyhulls re indeed highly fermentble in the cecum nd this incresed production of VFA would contribute to the energy needs of the horse. The increse in totl VFA concentrtions observed in our tril is similr to tht seen in previous studies with similr diets fed to ruminnts nd rbbits. This increse in totl VFA production suggests tht dditions of soyhulls to horse diets incresed microbil biomss in the cecum, contributing to incresed fecl N output nd reducing the pprent digestibility of N. Fecl N concentrtions (1.4, 1.7, 1.8, nd 2.5% N for diets contining 0, 25, 50, nd 75% SH respectively) incresed s dietry inclusion rtes of SH incresed (P < 0.02). Incresed fecl N ws observed in rbbits receiving SH s the sole forge source compred to those fed lflf hy.

4 Proportions of cecl propionte incresed linerly (P < 0.01) nd cubiclly (P = 0.03). Cecl propionte concentrtions from horses fed the 0% SH diet in our tril were similr to vlues observed in other trils when horses were fed grss-legume hy mixture. Addition of soyhulls to diets cuses n increse in propionte similr to tht observed when concentrte is dded to rtions. Acette to propionte rtios lso decresed both linerly (P = 0.02) nd cubiclly (P = 0.03) s the inclusion rtes of soyhulls incresed. Butyrte concentrtions decresed linerly (P < 0.01) s proportions of soyhulls in diets incresed. Cecl butyrte concentrtions observed in our tril re in greement with vlues reported in ponies fed clover either with or without ots. In our tril, there were no significnt differences (P > 0.16) between tretments for proportion of cette, isobutyrte, isovlerte, nd vlerte. Increses in proportions of propionte nd decreses in butyrte suggest chnges in microbil popultions bsed on chnges in vilble substrte nd ph of the cecum. Cecl ph decresed linerly (P = 0.01) s inclusion rtes of soyhulls in diets incresed. Cecl mmoni concentrtions (P = 0.68) were not linerly different with tretment (Tble 4), but the cubic response ws significnt (P = 0.01). Ammoni concentrtions in our tril re higher thn those observed for ponies fed timothy hy. Cecl ph decresed s inclusion rtes of soyhulls in diets incresed. However, this decrese in ph ws not lrge nd did not pproch levels indictive of subclinicl cidosis (less thn 6). Soyhulls pper to be n cceptble replcement for up to 70% of the totl forge in diets for horses. This feedstuff is economiclly fesible, redily vilble, pltble, nd digestible. Horses in our study redily consumed ll experimentl diets with no dverse rections, but longerterm feeding experiments should be conducted to confirm the sfety of these feeding recommendtions. Soyben hulls pper to stimulte cecl fermenttion nd re suitble replcement for hy in equine diets.

5 Tble 1. Composition of ingredients used in diets for horses Item Hy SH Diet b DM, % DM bsis OM, % NDF, % ADF, % Cellulose, % Lignin, % Acid Insol. Ash, % CP, % Soyben hulls. b hulls + 50% hy; 75% SH = 75% soyben hulls + 25% hy. Nutrient vlues re clculted bsed on nlyses of hy nd soyben hulls. Tble 2. Intke nd body weight of horses receiving diets contining soyben hulls Item Diet SEM Liner P vlue Totl intke, %BW Soyhulls, % totl intke < 0.01 BW, kg hulls + 50% hy; 75% SH = 75% soyben hulls + 25% hy. b Horses were offered 1.8% of body weight s feed DM.

6 Tble 3. Apprent digestibility (%) of diets contining soyben hulls offered to horses Item Diet SEM Liner P vlue b DM OM NDF ADF Cellulose Lignin Hemicellulose N <0.01 hulls + 50% hy; 75% SH = 75% soyben hulls + 25% hy. b Qudrtic nd cubic P-vlues were ll greter thn Tble 4. Cecl fluid mesurements from horses fed diets contining soyben hulls Item Diet SEM Liner P vlue Totl VFA, mm Acette, mol/100 mol Propionte mol/100 mol <0.01 Acette:Propionte rtio Isobutyrte, mol/100 mol Butyrte mol/100 mol <0.01 Isovlerte mol/100 mol Vlerte, mol/100 mol ph NH 3, mg/100 ml hulls + 50% hy; 75% SH = 75% soyben hulls + 25% hy.