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Thesis (MScAgric)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The objectives of this study were to determine the effects of supplementing oat silage (OS) with lucerne (LH) and oat hay (OH) on the production performance of lactating Jersey cows, as well as comparing the ruminal degradability of LH, OH and OS III Holstein and Jersey cows receiving a high forage diet and a high concentrate diet. In the first trial, five diets containing different combinations of OS and LH together with concentrate mixtures providing 26, 23, 20, 17 and 14% crude protein (CP) were fed to lactating Jersey cows. Lucerne hay was fed at 0, 2, 4, 6, and 8 kg DM/day while OS was fed ad libitum. Cows receiving only OS as a forage source had a lower (P<0.05) dry matter (DM) intake and produced less milk protein (P<0.05). Milk and fat yields as well as milk urea nitrogen (MUN) levels did not differ (P>0.05) between treatments. In the second trial, OS was fed with OH and a concentrate mixture containing 26% CP to lactating Jersey cows. Oat hay was fed at 0, 2, 4, 6, and 8 kg DMiday while OS was fed ad libitum. Cows that received OS together with 4 and 6kg OH, respectively had higher (P<0.05) DM intakes. Milk, fat, and protein yields as well as MUN levels did not differ (P>O.05) between treatments. The ruminal degradability of LH, OH and OS in Holstein and Jersey cows receiving (i) a high forage and (ii) a high concentrate diet was determined. The two breeds were also compared in terms of rumen pH levels, volatile fatty acids (VF A) and rumen ammonia nitrogen (NH3-N) concentrations as affected by time after feeding. The ruminal degradability of freeze dried (FD), oven dried (OD) and fresh oat silage (FS) in Jersey cows receiving a high forage diet was also determined. The ruminal DM, CP and NDF degradability of LH was higher (P<O.05) than that of OH and OS in both Holstein and Jersey cows when they were fed either a high forage or a high concentrate diet. When cows were fed a high forage diet, the effective DM degradability of OS was higher (P<O.05) in Holsteins although the CP degradation rates of LH and OH were higher (P<O.05) in Jerseys. When they were fed a high concentrate diet, Jerseys had higher (P<O.05) effective DM and NDF degradabilities and higher (P<O.05) DM and NDF degradation rates in LH while Holsteins had higher (P<O.05) effective CP degradability levels than Jerseys in OS. After feeding a high forage diet, pH levels declined while VFA and NH3-N concentrations increased (P<O.05) in both breeds. Jerseys had higher rumen pH, lower (P<O.05) VFA and lower NH3-N concentrations than Holsteins throughout the study. When cows were fed a high concentrate diet, Jerseys had higher (P<O.05) pH than Holsteins. A post-feeding decline (P<O.05) in pH was observed in both breeds. Fresh oat silage had a lower (P<O.05) effective degradability and degradation rates for DM, CP and NDF in comparison to FD and OD oat silage. The DM, CP and NDF degradation rates, as well as effective NDF degradability were higher (P<O.05) for FD silage, but effective DM and CP degradabilities were higher (P<O.05) for OD oat silage. It was concluded that on an oat silage diet, lactating Jersey cows should receive a minimum of 2kg LH or 4 to 6kg oat hay together with ad libitum OS to improve DM intake. When cows were fed a high concentrate diet, the ruminal degradability appeared to be superior in Jerseys than Holsteins. Jerseys also had higher rumen pH levels lower VFA and NH3-N concentrations than Holsteins. Feeding interval affects the rumen environment, pH declines while VF A and NH3-N concentrations increased. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van die aanvulling van hawerkuilvoer met lusemhooi (LH) en hawerhooi (HH) op die melkproduksie van Jerseykoeie te bepaal. Hiermee saam is die rumen degradeerbaarheid van hawerkuilvoer en lusemhooi ondersoek in Jersey en Holsteinkoeie wat 'n hoe-ruvoer en 'n hoe-kragvoer gebaseerde dieet ontvang het. In die eerste proef is vyf diete met verskillende peile van hawerkuilvoer en lusernhooi saam met kragvoere van verskillende ruproteienpeile (26, 23, 20, 17 en 14% RP) aan 10 lakterende Jerseykoeie gevoer. Hawerkuilvoer is ad libitum voorsien en lusemhooi is teen vlakke van 0, 2, 4,6 en Skg droemateriaal (DM) per dag gevoer. Die DM-inname en melkproteienproduksie van koeie wat hawerkuilvoer as die enigste ruvoerbron ontvang het, was laer (P<0.05) as ander ruvoerkombinasies. Die melk- en vetproduksie, asook melk-ureumstikstofpeile het nie tussen behandelings verskil nie (P>0.05). In die tweede proef is hawerkuilvoer saam met hawerhooi (soortgelyk as Proef 1) gevoer. Die kragvoerkomponent van al die ruvoerkombinasies het 26% RP bevat. Die koeie wat hawerkuilvoer en 4 of 6kg hawerhooi as ruvoere ontvang het, het hoer (P<O.05) droemateriaalinnames gehad. Melk, vet en proteienproduksie asook melk-ureumstikstofpeile het nie tussen ruvoerkombinasies verskil nie (P>O.05). Die rumendegradeerbaarheid van lusemhooi, hawerhooi en hawerkuilvoer is bepaal in Holstein en Jerseykoeie wat (i) 'n hoe ruvoer- en (ii) 'n hoe kragvoerdieet ontvang het. Die rumen pH, vlugtige vetsuur en rumen-ammoniakkonsentrasies, soos beinvloed deur tyd na voeding, is ook tussen rasse vergelyk. Die rumendegradeerbaarheid van vars, oondgedroogde en vriesgedroogde hawerkuilvoer is ook bepaal. Die rumen DM, RP en NDF degradeerbaarhede van lusemhooi was hoer (P<O.05) as by hawerhooi en hawerkuilvoer in beide Holstein en Jerseykoeie wat (i) 'n hoe ruvoer- en (ii) 'n hoe kragvoerdieet ontvang het. Op 'n hoe ruvoerdieet, was effektiewe DM degradeerbaarheid van hawerkuilvoer by Holsteins hoer (P<O.05) as by Jerseys. Jerseykoeie het egter 'n hoer (P<O.05) RP degradeerbaarheidstempo van lusemhooi en hawerhooi gehad. Jerseykoeie op 'n hoe kragvoerdieet, het hoer (P<O.05) effektiewe DM en NDF degradeerbaarhede getoon. Hulle het egter 'n laer (P<O.05) effektiewe ruprotein (RP) degradeerbaarheid by hawerkuilvoer as Friese gehad. Jerseykoeie op lusemhooi het ook 'n hoer (P<O.05) DM en NDF degradeerbaarheidstempo getoon. Jerseykoeie wat 'n hoe ruvoerdieet ontvang het, het 'n hoer (P<O.05) rumen- pH en laer (P<O.05) vlugtige vetsuur- en rumen-ammoniak konsentrasies as Holsteinkoeie gehad. Jerseykoeie wat 'n hoe kragvoerdieet ontvang het, het ook 'n hoer (P<O.05) rumen- pH as Holsteinkoeie gehad. By al die koeie is gevind dat rumen- pH na voeding afgeneem het (P<O.05). Vlugtige vetsuur- en rumen-ammoniakkonsentrasies was laag voor voeding en het daama toegeneem (P<O.05). Vars hawerkuilvoer het laer (P<O.05) effektiewe DM, RP en NDF degradeerbaarhede en degradeerbaarheidstempo's as oond- en vriesgedroogde hawerkuilvoer gehad. Die vriesgedroogde kuilvoer het hoer (P<O.05) DM, RP en NDF degradeerbaarheidstempo's sowel as effektiewe NDF degradeerbaarhede gehad. Oondgedroogde kuilvoer het daarinteen hoer (P<O.05) effektiewe DM en RP degradeerbaarhede gehad. Die gevolgtrekking is gemaak dat lakterende Jerseykoeie ten minste 2kg lusemhooi of 4- 6kg hawerhooi per dag moet ontvang wanneer hulle hawerkuilvoer as ruvoerbron ontvang. Op 'n hoe kragvoerdieet, het dit gebleik dat die rumendegradeerbaarheid van vesel by Jerseys beter is as by Holsteins. Die rumen- pH is hoog voor voeding, maar dit neem af nadat die koeie gevreet het. Die rumen- pH van Jerseys was hoer as by Holsteins. Die vlugtige vetsure en rumen-ammoniakkonsentrasies blyk laag te wees voor voeding en neem daama toe. Konsentrasies was hoer by Holstein as by Jerseys.

162 leaves printed on single pages, preliminary pages i- vii and numbered pages 1-152. Includes bibliography and abbreviations. / Digitized at 600 dpi grayscale to pdf format (OCR), using a Bizhub 250 Konica Minolta Scanner. / Thesis (PhD(Agric))--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Maize, forage sorghum, lucerne, oats, barley and triticale are the most common silage crops in South Africa, while tropical grasses like Eragrostis curvula and Digitaria eriantha are ensiled to a lesser extent. The aim of this study was to determine the effect of adding a lactic acid bacterial inoculant to E. curvula, D. eriantha, lucerne, forage sorghum, maize and oat silage. The effect of the addition of a lactic acid bacterial inoculant when ensiling E. curvula on the fermentation dynamics during ensiling and the aerobic stability of the silage was determined. The addition of the lactic acid bacterial inoculant to E. curvula at ensiling resulted in a more rapid lowering in pH and improved preservation. Inoculated silage had a higher lactic acid content, less protein breakdown and a lower butyric acid content compared to that of the control silage. Both silages were stable when exposed to air for five days. Digitaria eriantha was ensiled, with or without the addition of a lactic acid bacterial inoculant containing Lactobacillus plantarum. Streptococcus faecium and Pediococcus acidilactici together with the enzymes, cellulase, hemicellulase and amylase. The addition of the inoculant resulted in a more rapid drop in pH, a higher level of lactic acid, an increase in the number of lactic acid bacteria, less protein breakdown and lower numbers of enterobacteria, clostridial spores, yeast and mould compared to the control silage. Digitaria eriantha hay, control and inoculated silage diets were fed to 24 Merino rams (n = 8 per treatment) to determine intake and digestibility. The intake of diets consisting of 90.9% D. eriantha hay, control silage or inoculated silage, differed significantly (p<0.05) at 1395, 1540 and 1848 g DM/day, respectively. The in vivo organic matter digestibility (glkg) of D. eriantha hay, untreated silage and inoculated silage diets was 561, 546, 574, respectively. The addition of the bacterial inoculant when ensiling D.eriantha resulted in better preservation, improved aerobic stability, as well as a higher in vivo organic matter digestibility and intake of D. eriantha silage. The addition of an inoculant or molasses to lucerne (Medicago sativa), ensiled in laboratory silos was investigated. The addition of the additives resulted in an increased preservation rate as indicated by a more rapid lowering of pH, a faster rate of lactic acid production and less protein breakdown compared to control silage. The inoculant was more effective than the molasses in improving the rate of preservation. The aerobic stability of lucerne silage was not affected by inoculation or the addition of molasses. The addition of an inoculant to wilted big bale lucerne silage was studied. The inoculant improved silage quality as indicated by a lower pH, higher lactic acid content, lower ammonia nitrogen content and lower level of butyric acid in inoculated silage compared to the control lucerne silage. The composition of big round bale lucerne silage differed markedly from that of lucerne ensiled in laboratory silos as the former had a higher pH, ammonia nitrogen, butyric acid and acetic acid content and a lower lactic content. Whole crop forage sorghum cultivar FS2 was harvested at the late bloom (20.7% DM) and soft dough (28.9% DM) stages of maturity and ensiled in laboratory silos with the addition of commercial silage inoculants. At both stages of maturity the inoculants caused a more rapid rate of pH decline and a higher amount of lactic acid production. All the silages were well preserved. Silages of the sorghum ensiled at the late bloom stage with all treatments were stable after 5 days of aerobic exposure, whereas sorghum ensiled at the soft dough stage with the addition of the inoculants deteriorated upon aerobic exposure. It is concluded that addition of lactic acid bacterial inoculants to mature sorghum at ensiling might impair the aerobic stability of the silage. The yield, nutritional value and production potential of silage made from twenty one maize hybrids was compared. It was concluded that maize hybrids did differ in metabolizable energy content, rate of digestion, predicted intake and predicted milk production potential. The content of NDF and ADF did not differ between the maize hybrids used in this study and could therefore not be used to predict nutritional value or production potential. Maize was harvested at the hard dough stage and ensiled with or without the addition of a lactic acid bacterial inoculant in laboratory silos and in 210 litre drums. The adding of the inoculant to maize at ensiling did not result in a more rapid drop in pH and higher levels of lactic acid. The intake and growth of South African Mutton Merino lambs fed inoculated and untreated maize silage diets was determined. The average daily gain of lambs fed a diet consisting of either 60% control or inoculated maize silage over a growth period of 60 days was 239 ± 26 and 255 ± 44 g/day, respectively. Although the laboratory study showed very little effect of adding a lactic acid bacterial inoculant to maize at ensiling, lambs tended to consume more of the inoculated silage. In the second study the effect of the addition of a lactic acid bacterial inoculant with an enzyme to maize at ensiling on the fermentation dynamics during ensiling, aerobic stability of the silage, the intake, milk production and milk composition of Jersey cows fed maize silage diets was determined. The inoculant did not result in a more rapid lowering of the pH or a more rapid lactic acid production compared to untreated maize silage made in laboratory silos. Both the control and inoculated maize silages were well preserved. The addition of the inoculant to maize at ensiling improved the palatability, intake and the aerobic stability of maize silage compared to the untreated control maize silage. Milk production, milk composition, live weight and condition score of Jersey cows was not significantly affected by the addition of the inoculant to maize silage. The effect of the addition of an enzyme containing lactic acid bacterial inoculant to big bale oat (Avena sativa, cv Cederberg) silage on silage composition, silage intake, milk production and milk composition of Jersey cows was determined. The crop was cut at the bloom stage, wilted and ensiled in big round bales. The inoculant, Sil-All, was applied during the baling process on half of the bales. Silages were fed to Jersey cows in an intake and milk production study. Both the control and inoculated oat silages were well preserved. The inoculated oat silage had a lower level of butyric acid than the control oat silage. Cows fed the inoculated oat silage produced more (P=O.05) milk (17.7 kg/day) than cows fed the control oat silage (16.7 kg/day). The addition of a lactic acid bacterial inoculant to big bale oat silage improved silage composition and animal performance. This study clearly showed that the composition of silages made in bunker silos under commercial farm conditions differ largely from that of silages made in small scale laboratory silos. When the effect of silage additives on aerobic stability of silage is determined the evaluation should include studies on large scale bunker silages. Evaluation of silage additives should include intake and animal production studies. / AFRIKAANSE OPSOMMING: Mielies, voersorghum, lusem, hawer, gars en korog word algemeen as kuilvoer gewasse benut terwyl tropiese grasse soos Eragrostis curvula en Digitaria eriantha tot 'n mindere mate ingekuil word. Die doel van hierdie studie was om die invloed van 'n melksuurbakterieseinokulant op E. curvula-, D. eriantha-, lusem-, voersorghum-, mielie- en hawerkuilvoer te bepaal. Die invloed van 'n melksuurbakteriese-inokulant op die fermentasiedinamika en die aerobiese stabiliteit van E. curvula-kuilvoer is bepaal. Die toediening van die melksuurbakterieseinokulant tot E. curvula tydens inkuiling het 'n vinniger tempo van pH daling en beter preservering tot gevolg gehad in vergelyking met kontrole kuilvoer. Inokulant behandelde kuilvoer het 'n hoer melksuurinhoud, minder protei'en afbraak en 'n laer bottersuurinhoud as kontrole kuilvoer gehad. Beide kuilvoere was stabiel tydens blootstelling aan lug vir vyf dae. Digitaria eriantha is ingekuil met ofsonder die toediening van 'n melksuurbakteriese-inokulant wat Lactobacillus plantarum. Streptococcus faecium en Pediococcus acidilactici sowel as die ensieme, sellulase, hemisellulase and amilase bevat het. Die inokulant het 'n vinniger tempo van pH-daling, hoer vlakke van melksuur en melksuurbakterie, minder protei'en afbraak en laer getalle van enterobakterie, klostridiale spore, giste and swamme in vergelyking met die kontrole tot gevolg gehad. Digitaria eriantha hooi, kontrole kuilvoer en gei'nokuleerde kuilvoer diete is aan 24 Merino ramme (n = 8 per behandeling) gevoer vir bepaling van inname en verteerbaarheid. Die inname van diete wat uit 90.9% D. eriantha hooi, kontrole kuilvoer of gei'nokuleerde kuilvoer bestaan het, het betekenisvol (p<0.05) verskil en was 1395, 1540 en 1848 gDM/dag, respektiewelik. Die in vivo organiesemateriaal verteerbaarheid (gIkg) vanD. eriantha hooi, kontrole kuilvoer en geYnokuleerde kuilvoer was 561, 546, 574, respektiewelik. Die toediening van die bakteriese-inokulant tydens inkuiling vanD. eriantha het beter preservering, verbeterde aerobiese stabiliteit asook 'n hoer in vivo organiesemateriaal verteerbaarheid van D. eriantha kuilvoer tot gevolg gehad. Die effek van toediening van 'n melksuurbakteriese-inokulant en van molasse tot lusem (Medicago sativa) ingekuil in laboratoriumsilos is ondersoek. Die inokulant toediening en molasse toediening het die tempo van preservering versnel, die pH het vinniger gedaal, melksuur is teen 'n hoer tempo geproduseer en minder proteYen afbraak het plaasgevind in vergelyking met die kontrole kuilvoer. Die tempo van preservering is meer effektief deur toediening van die inokulant verhoog as deur die toediening van molasse. Die aerobiese stabiliteit van lusernkuilvoer is nie beYnvloed deur die toediening van inokulant ofmolasse nie. Die effek van die toediening van 'n melksuurbakteriese-inokulant tot groot rondebaal lusernkuilvoer is ondersoek. Die inokulant het die kwaliteit van die kuilvoer verbeter en het 'n laer pH, hoer melksuur, laer ammoniak stikstofen laer bottersuurinhoud in rondebaallusernkuilvoer tot gevolg gehad in vergelyking met kontrole kuilvoer. Groot rondebaallusernkuilvoer het grootliks verskil van lusernkuilvoer wat in laboratoriumsilos ingekuil is. Die rondebaal kuilvoer het 'n hoer pH, hoer ammoniak-stikstof-, bottersuur- en asynsuurinhoud en 'n laer melksuurinhoud gehad as laboratorium lusernkuilvoer. Voersorghum kultivar FS2 is op die laat blom (20.7% DM) en op die sagte deeg (28.9% DM) stadium met die byvoeging van melksuurbakteriese-inokulante ingekuil in laboratoriumsilos. Toediening van beide inokulante tot sorghum hetop beide die inkuilstadiums gelei tot 'n vinniger tempo van pHdaling en meer melksuurproduksie. Aile kuilvoere insluitend die kontrole kuilvoer was goed gepreserveer. Kontrole sowel geYnokuleerde sorghumkuilvoer ingekuil op die laat blomstadium was stabiel tydens aerobiese blootstelling vir 5 dae. Sorghumkuilvoer ingekuil op die sagtedeegstadium met die byvoeging van inokulante was onstabiel tydens aerobiese blootstelling. Die toediening van melksuurbakteriese-inokulante tot sorghum wat op die sagtedeegstadium ingekuil word kan aerobiese stabiliteit van die kuilvoer grootliks benadeel. Die opbrengs, voedingswaarde en produksiepotensiaal van kuilvoer gemaak van 21 mielie hibriede is vergelyk. Verskille in metaboliseerbare energie inhoud, tempo van vertering, voorspelde inname en voorspelde melkproduksie het tussen mielie hibriede voorgekom. Die neutraalbestandevesel- en suurbestandeveselinhoud het nie verskil tussen hibriede nie en derhalwe kon dit nie gebruik word om voedingswaarde ofproduksiepotensiaal te beraam rue. Mielies is op die hardedeegstadium met of sonder die toediening van 'n melksuurbakterieseinokulant in laboratoriumsilos en 210 liter dromme ingekui!. Die toediening van die inokulant het geen invloed op tempo van pH-daling ofproduksie van melksuur gehad nie. Die inname en groei van SA Vleismerino lammers wat 'n dieet bestaande uit 60% kontrole of inokulant behandelde mieliekuilvoer ontvang het, is bepaa!. Die gemiddelde daaglikse toename van lammers was 239 ± 26 and 255 ± 44 g/dag vir die kontrole en inokulant mieliekuilvoer dieet respektiewelik. Alhoewel die laboratoriumstudie weinig verskille tussen die kontrole en die geYnokuleerde mieliekuilvoer getoon het, het lammers geneig om meer van die geYnokuleerde mieliekuilvoer in te neem. In die tweede studie met mieliekuilvoer is die effek van toediening van 'n melksuurbakteriese-inokulant met ensieme, op die ferrnentasiedinamika tydens inkuiling, die aerobiese stabiliteit van mieliekuilvoer asook die inname, melkproduksie en melksamestelling van Jersey koeie bepaa!. Die inokulant het nie die tempo van pH daling en produksie van melksuurverhoog nie en beide kontrole en geYnokuleerde mieliekuilvoerwas goed gepreserveer. Die toediening van die inokulant tot mieliekuilvoer het die smaaklikheid, inname en die aerobiese stabiliteit van mieliekuilvoer verhoog in vergeiyking met kontrole mieliekuilvoer. Melkproduksie, melksamestelling, liggaamsmassa en kondisiepunt van Jersey koeie is nie betekenisvol beYnvloed deur die toediening van die inokulant tot mieliekuilvoer nie. Die effek van die toediening van 'n ensiem bevattende melksuurbakteriese-inokulant tot groot rondebaal hawer (Avena sativa, cv Cederberg) kuilvoer op die samestelling van kuilvoer, kuilvoerinname, melkproduksie en melksamestelling van Jersey koeie is bepaa!. Die gewas is gesny op die blomstadium, verwelk en as rondebaalkuilvoer gepreserveer. Die inokulant, Sil-All, is tydens die baalproses toegedien op die helfte van die bale. Kuilvoere is aan Jersey koeie gevoer in 'n inname en melkproduksiestudie. Beide die kontrole en geYnokuleerde hawerkuilvoer was goed gepreserveer. Die bottersuurinhoud van geYnokuleerde hawerkuilvoer was laer as die van die kontrole hawerkuilvoer. Koeie wat geYnokuleerde hawerkuilvoer gevoer is het meer (P=0.05) melk (17.7 kg/dag) geproduseer as koeie wat kontrole hawerkuilvoer ontvang het (16.7 kg/dag). Die toediening van 'n melksuurbakteriese-inokulant het kuilvoer kwaliteit en diereproduksie verbeter. Hierdie studie wys duidelike verskille uit tussen kuilvoer wat in bunkersilos onder kommersiele toestande ingekuil is, en kuilvoer wat in laboratoriumsilos gemaak is. Wanneer die effek van kuilvoerbymiddels op die aerobiese stabiliteit van kuilvoer bepaal word behoort finale evaluasie gedoen te word op kuilvoer gemaak in bunkersilos soos onder plaastoestande plaasvind. Evaluasie van kuilvoerbymiddels behoort inname en diereproduksiestudies in te sluit.