Growth, carcass composition and profitability of broilers given post-finisher or free-choice grain cereal

Magolego, Tebogo Pearl (2001)

Thesis (M.Phil.(Agricultural Systems Management)) -- Stellenbosch University, 2001

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Thesis

ENGLISH ABSTRACT: Broilers of a mixed sex aged 4 weeks were used to determine whether feeding program affected the performance and profitability of birds. The performance of the birds was measured in terms of feed intake, live weight gain and carcass composition. Financial analyses were carried out to determine which of the feeding programs would be economically efficient in terms of feed cost per live weight gain. The feeding programs followed were (i) a complete diet, (ii) free choice feeding of a complete diet with cereal grains, and (iii) cereal grain fed solely. The treatments used were: 1) Post-finisher diet as a control, 2) Post-finisher plus cracked yellow maize, 3) Post-finisher plus whole wheat, 4) Post-finisher plus whole sorghum, 5) Cracked yellow maize, 6) Whole wheat and 7) Whole sorghum The experiment was conducted over a period of four weeks divided into two phases of two weeks each. During phase one the birds were divided into four groups. Three groups were offered a complete diet and a cereal on a free choice basis, while the other group was fed on a complete diet, which served as the control experiment. In the second phase of the experiment, the three choice fed groups were subdivided into two groups each. The subgroups were offered sole grains while the other groups continued with the treatments they received in the first phase. All the diets were fed ad libitum. The results showed that there were no significant differences between treatments and the control with regard to feed intake, live weight gain, and carcass composition in the first phase of the experiment. During the second phase of the experiment, choice-fed birds had the highest live weight gain in the order of PF + maize> PF + sorghum> PF + wheat, but were not significantly different from the control group. Post-finisher plus maize fed birds had the highest live weight gain and their carcasses contained low body fat. Sole grain fed birds had lower live weight gains compared to the choice-fed and control groups in the order of wheat > maize> sorghum. The live weight of the latter groups changed by a small margin from the age of six to eight weeks. Of the three sole grain fed groups, the wheat fed group had the highest live weight gain and their carcass composition showed lower levels of body fat. Financial analyses carried out at the end of the experiment showed that, the group choice-fed with maize had the lowest feed cost per live weight gain compared to the other choice-fed groups and the control group. Among the sole grain fed groups, the wheat fed group had the lowest feed costs per live weight gain. It was therefore concluded, within the experimental errors, that choice feeding with any of the grains or feeding the grains solely to broilers that have reached slaughter weight, has no detrimental effect on the birds. The choice-fed birds performed better than the control group, while the sole grain fed birds performed as good as the control group. Both the choice feeding and sole grain feeding programs were economically efficient when compared to the complete diet feeding program, in terms of feed cost per live weight gain

AFRIKAANSE OPSOMMING: Vier weke oue braaikuikens, van albei geslagte, is gebruik om te bepaal of die tipe voerprogram, prestasie en winsgewendheid beinvloed. Prestasie is gemeet deur middel van voerinname, massa toename en karkassamestelling. Finansiële ontledings is gedoen om die mees doeltreffende voerprogram te bepaal in terme van voerkoste per lewende gewig toename. Die voerprogramme gevolg is (i) 'n volledige rantsoen (ii) vrye keuse voeding met 'n volledige rantsoen en 'n graan en (iii) slegs 'n graan. Die volgende behandelings is gevolg: 1) Na-afrondings (NA) rantsoen as die kontrole 2) Na-afrondings (NA) rantsoen en gebreekte geelmielies 3) Na-afrondings (NA) rantsoen en koring (heel) 4) Na-afrondings (NA) rantsoen en sorgum (heel) 5) Gebreekte geelmielies 6) Koring (heel) 7) Sorgum (heel) Die proefperiode van vier weke, is opgedeel in twee fases van twee weke elk. Gedurende die eerste fase, is die kuikens in vier groepe verdeel, waarvan drie 'n vrye keuse van 'n volvoer en 'n graan gekry het en die vierde groep slegs 'n volvoer gekry het. Gedurende die tweede fase is die drie groepe met vrye keuse, elk onderverdeel in twee groepe. Die sub-groepe het slegs graan ontvang, terwyl die ander groepe dieselfde behandeling gekry het as gedurende die eerste fase. Alle rantsoene is ad libitum gevoer. In die eerste fase van die proef was daar geen betekenisvolle verskille in voer inname, massa toename en karkassamestelling, tussen die behandelings en kontrole groep nie. In die tweede fase het kuikens met keuse voeding, die hoogste massa toename gehad met NA + mielies> NA + sorgum > NA + koring. Die kuikens wat beide die na-afrondings rantsoen en mielies gekry het, het die hoogste massa toename gehad met die minste vet in die karkasse. Kuikens wat op slegs 'n graan rantsoen was, het laer massa toenames gehad as die kuikens op keuse voeding en die kontrole met koring > mielies > sorgum. Die lewende massa van laasgenoemde groepe het min verander vanaf ses tot agt weke ouderdom. Vandie drie groepe wat slegs graan gevreet het, het die koring-groep die meeste toegeneem in massa en het minder liggaamsvet gehad. Finansiële ontledings aan die einde van die proef, het bepaal dat die groep van 'n vrye keuse met mielies, die laagste voerkoste per lewende massa toename gehad het in vergelyking met die kontrole en die ander groepe met vrye keuse. Die groep wat slegs koring gevoer is, het die laagste voerkoste per lewende massa toename gehad van die groepe wat slegs graan gevoer is. Die gevolgtrekking kan gemaak word dat, binne eksperimentele foute, keuse voeding, ongeag die graansoort, of die voer van graan alleen, geen nadelige effek op braaikuikens het wat reeds slagmassa bereik het nie. Die kuikens wat keusevoeding gehad het, het beter presteer as die kontrole groep, terwyl die kuikens wat slegs graan gevreet het, net so goed soos die kontrole groep presteer het. In vergelyking met 'n volledige rantsoen voerprogram is beide keusevoeding en slegs graan voerprogramme finansieel doeltreffend.

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