The evaluation of locally produced canola oilcake meal as an alternative protein source in the diets of slaughter ostriches (Struthio camelus var. domesticus)

Van der Merwe, Johanet (2019-04)

Thesis (MScAgric)--Stellenbosch University, 2019.


ENGLISH ABSTRACT: Feeding costs make out ~75% of all expenses in an intensive ostrich production system. Protein is one of the major components in ostrich diets. Currently, the main source of protein used in animal feed is soybean oilcake meal (SOCM). This protein source is, however, expensive as it is an imported raw material. In order to decrease feeding costs a locally produced alternative source of protein; canola oilcake meal (COCM) was identified. It is important to evaluate the possible influence alternative raw materials might have on the production and slaughter traits of animals as nutrition has a direct influence on production. The use of COCM is limited in animals’ diets due to its glucosinolate content. Glucosinolates are anti-nutritional factors that reduce palatability. Therefore, a study to determine whether or not the glucosinolate content has an influence on ostriches’ feed intake was conducted. Grower ostriches in a free-choice system had access to five iso-nutritious diets with different inclusion levels of COCM, replacing SOCM in increments of 0%, 25%, 50%, 75% and 100%. The control diet (the diet with 0% inclusion of COCM) showed to be the preferred diet by having the highest average intake per bird per day over the entire trial period (736.1 ± 74.1 g/bird/day). The intake of this diet made up to 35% of the total daily intake while the diets containing COCM were consumed at levels lower than 18% of the total DMI per bird. As the preference trial showed that the inclusion of COCM in ostrich diets might have a negative influence on feed intake in a free-choice system, production and slaughter traits were evaluated in the following trial. Ostriches were reared from 77-337 days of age on five iso-nutritious diets, each with a different inclusion level of COCM, replacing 0%, 25%, 50%, 75% and 100% of SOCM, respectively. Bird weight and feed intake were measured over the entire growth period. Results showed that the replacement of SOCM with COCM had little effect on the performance of ostriches. The ostriches that were reared on the diet replacing 75% of SOCM had the best performance in terms of slaughter and production traits. Typically, production of the end-products (feather, leather and meat yield and quality) is directly influenced by nutrition. The replacement of SOCM with COCM had no influence on the production and quality characteristics of feathers, skin or meat. This study concludes that the COCM can be used as a cheaper alternative protein source in the diets of slaughter ostriches without having any detrimental effect on growth, production parameters and slaughter traits. This will not only be beneficial to the ostrich industry but it will also benefit the local grain industry.

AFRIKAANSE OPSOMMING: Ongeveer 75% van al die uitgawes wat gepaardgaan met intensiewe volstruisboerdery, word toegeskryf aan voerkoste. Een van die hoofkomponente in volstruisdiëte is proteïen. Sojaboonoliekoek word tans hoofsaaklik gebruik as proteïenbron in dierevoer. Omdat die aanvraag na sojaboonoliekoek hoër is as die produksie daarvan in Suid-Afrika, word groot hoeveelhede sojaboonoliekoek jaarliks ingevoer. Dit laat die koste van voer aansienlik styg. In ‘n poging om voerkoste te verlaag, is kanola-oliekoek as alternatiewe, plaaslik beskikbare proteïenbron geïdentifiseer. Omdat voeding ‘n direkte invloed op produksie het, is dit belangrik om die moontlike invloed wat alternatiewe rou materiale mag hê, te ondersoek. Kanola-oliekoek het ‘n hoë glikosinolaatinhoud wat die insluiting daarvan in dierevoeding beperk. Glikosinolate is antinutriënte wat die smaaklikheid van voer verlaag. ‘n Studie is gedoen om te bepaal tot watter mate die glikosinolaatinhoud van voer ‘n invloed het op voerinname van volstruise. Volstruise (in die groeifase) is in ‘n vrye-keuse sisteem van vyf verskillende diëte voorsien. Elke dieet het ‘n verskillende insluitingsvlak van kanola oliekoek bevat. Die kanola-oliekoek het onderskeidelik 0%, 25%, 50%, 75% en 100% van die sojaboonoliekoek wat as proteïenbron in die diëte gedien het, vervang. Die volstruise het ‘n duidelike voorkeur vir die kontrole dieet (wat geen kanola-oliekoek bevat het nie) getoon. Oor die hele proeftydperk was die gemiddelde inname van hierdie dieet 35%, terwyl die inname van die ander diëte laer as 18% elk was. Omdat die voorkeurproef aangedui het dat die insluiting van kanola-oliekoek in volstruisdiëte ‘n negatiewe invloed op voerinname in ‘n vrye-keuse sisteem het, is die produksie- en slageienskappe geëvalueer. In hierdie studie is volstruiskuikens vanaf die ouderdom van 77 dae tot 337 dae oud grootgemaak op vyf diëte. Vir elke dieet is die sojaboonoliekoek weereens varvang met kanola-oliekoek (0%, 25%, 50%, 75% en 100%, onderskeidelik). Voerinname en die gewigte van die volstruise is gedurende die hele proeftydperk gemonitor. Alhoewel die vervanging van sojaboonoliekoek met kanola-oliekoek in volstruisdiëte min tot geen effek op produksie gehad het, het die volstruise wat grootgemaak is op die dieet waarin 75% van die sojaboonoliekoek vervang is die beste produksie getoon. Die resultate na die evaluering van die eindprodukte (naamlik vere-, leer- en vleiskwaliteit en opbrengs) het getoon dat die vervanging van sojaboonoliekoek met kanola-oliekoek geen invloed op die produksie en kwaliteit van hierdie produkte het nie. Die algehele gevolgtrekking van hierdie studie is dat kanola-oliekoek geskik om as proteïenbron te dien in diëte van slagvolstruise sonder dat enige nadelige effek op groei, produksie parameters en slageienskappe waargeneem sal word. Die gebruik van kanola-oliekoek sal nie net tot voordeel van die volstruisbedryf wees nie, maar sal ook tot voordeel vir die plaaslike graanindustrie wees.

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