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dc.contributor.advisorVan der Merwe, H. J.
dc.contributor.advisorHayes, J. P.
dc.contributor.authorPhitsane, Pulane Mirriam
dc.date.accessioned2018-01-25T06:38:17Z
dc.date.available2018-01-25T06:38:17Z
dc.date.issued2006-05
dc.identifier.urihttp://hdl.handle.net/11660/7706
dc.description.abstractEnglish: A study was conducted to investigate the effect of variation in body weight (BW) of broiler breeder hens at onset of lay (23 weeks of age) on subsequent egg production parameters and eggshell quality (27 to 60 weeks of age). Ross broiler breeder hens (n = 198) reared under restricted feeding were randomly placed in individual cages at 23 weeks of age. Hens were divided into low (LBW), medium (MBW), and high (HBW) body weight groups as follows: 2007 - 2447 g, 2645 - 2777 g and 2975 - 3445 g, respectively. The production parameters were recorded on a three weekly interval during the experimental period. The hens in the HBW group laid eggs that were significantly (P<0.05) heavier than hens in the other two groups during the initial stages of lay (27 to 30 weeks of age). The HBW hens had a statistically (P<0.05) higher egg content in comparison to the other two groups only during the first production interval (week 27 of age). Egg production was not significantly (P>0.05) affected by BW at the onset of lay. HBW hens at the onset of lay resulted in a higher mean egg output (P=0.0071) from the commencement of lay up to 36 weeks of age. HBW hens laid eggs with thicker broad and equator ends than the MBW and LBW hens during the first 10 weeks of lay. No statistical differences (P>0.05) were observed in shell percentage, shell per unit surface area and egg surface area between the different BW groups. BW variation significantly affected shell weight from 27 to 60 weeks of age, as high BW was associated with heavier shell weight. The results suggest that a high BW at the onset of lay plays a positive role on the performance (egg weight, egg output, egg content and eggshell thickness) of laying broiler breeder hens during the initial stages of lay. In a second trial the effect of BW at the onset of lay on calcium retention and excretion of broiler breeder hens during the different stages of lay was investigated. Ninety randomly selected hens from the broiler breeder hens as described in the first paragraph were used in the investigation. The experiment was conducted for a period of 15 weeks (27 to 42 weeks of age). Excreta samples were collected during a 7-day collection period at weeks 27, 33, 36, and 42 of age. The hens in the HBW group excreted a significantly (P<0.05) higher amount of calcium into the eggshells than the LBW and MBW hens with exception of week 27-33 of age; this was related to a higher daily calcium intake by the HBW hens though calcium intake did not differ statistically (P>0.05). No significant differences were observed in calcium retention, faecal calcium excretion and total calcium excretion among the BW groups throughout the 15-week period of the trial. It seems that calcium homeostasis was maintained by the broiler breeder hens irrespective of the BW status at the onset of lay. It was concluded that BW of the hens at the onset of lay as a point of reference for subsequent egg production and eggshell quality is probably not sufficient. Other factors like change in BW grouping over the laying period and energy requirements of the hens may also be important to consider.en_ZA
dc.description.abstractAfrikaans: ‘n Studie is uitgevoer om die invloed van variasie in liggaamsgewig (LG) van braaikuikenhenne aan die begin van die lêperiode (23 weke ouderdom) op die daaropvolgende eierproduksie parameters en eierdopkwaliteit (27 tot 60 weke ouderdom) te ondersoek. Ross braaikuikenhenne (n = 198) wat op innamebeperkte diete grootgemaak is, is ewekansig in individuele hokke op 23 weke ouderdom geplaas. Die henne is onderskeidelik in laag (LLG), gemiddel (MLG) en hoë (HLG) liggaamsgewiggroepe as volg ingedeel: 2007 g- 2447 g, 2645 g- 2777 g and 2975 g – 3445 g. Die produksieparameters is met drieweke intervalle gedurende die eksperimentele periode ingesamel. Die henne in die HLG groep het betekenisvol (P< 0.05) swaarder eiers as die twee ander groepe gedurende die begin stadium van die lêperiode (27 tot 30 weke ouderdom) geproduseer ‘n Statisties (P< 0.05) hoër eiereinhoud in vergelyking met die ander twee groepe is vir die HLG groep henne gedurende week 27 waargeneem. Eierproduksie is nie statisties betekenisvol (P> 0.05) deur LG aan die begin van die lêperiode beïnvloed nie. HLG henne aan die begin van die lêperiode het ‘n hoër (P = 0.0071) eiermassa vanaf die begin van die lê tot 36 weke ouderdom tot gevolg gehad. HLG henne het gedurende die eerste 10 weke van die lêperiode ‘n verhoogde (P< 0.05) eierdopdikte tot gevolg gehad. Geen statisties betekenisvolle (P> 0.05) verskille in persentasie dop, eierdopgewig per eenheidsoppervlakte en eieroppervlakte is tussen die verskillende LG groepe waargeneem nie. Variasie in LG het eierdopgewig vanaf 27 tot 60 weke ouderdom betekenisvol (P< 0.05) beïnvloed en het ‘n HLG met n swaarder eierdopgewig gepaard gegaan. Die resultate het aangedui dat ‘n HLG aan die begin van die lêperiode ‘n positiewe rol speel in die prestasie (eiergewig, eiermassa, eierhoud en eierdopdikte) van braaikuikenhenne gedurende die vroeë stadiums van die lêperiode. In ‘n tweede studie is die invloed van LG van braaikuikenhenne aan die begin van die lêperiode op kalsiumretensie en kalsiumekskresie gedurende verskillende stadia van die lêperiode ondersoek. Negentig ewekansig geselekteerde henne afkomstig van die braaikuikenhenne beskryf in die eerste paragraaf is in die ondersoek gebruik. Die studie is vir ‘n periode van 15 weke (27 tot 42 weke ouderdom) uitgevoer. Mismonsters is gedurende ‘n 7 dae kolleksieperiode op 27, 33, 36 en 42 weke ouderdom geneem. Die henne van die HLG groep het met die uitsondering van weke 27-33 betekenisvol (P< 0.05) meer kalsium in eierdoppe as die LLG en MLG henne uitgeskei. Dit was verwant aan die hoër kalsiuminname van die HLG henne, alhoewel kalsiuminname nie statisties betekensvol (P> 0.05) verskil het nie. Geen betekenisvolle (P> 0.05) verskille in kalsiumretensie, miskalsiumuitskeiding en totale kalsiumuitskeiding is gedurende die 15 weke proefperiode waargeneem nie. Dit blyk dat kalsiumhomeostase deur die braaikuikenhenne gehandhaaf is ongeag die LG status aan die begin van die lêperiode. Daar is tot die slotsom gekom dat LG van henne aan die begin van die lêperiode as ‘n punt van verwysing vir die daaropvolgende eierproduksie en eierdopkwaliteit, waarskynlik nie voldoende is nie. Ander faktore soos ‘n verandering in LG groepering gedurende die lêperiode en energiebehoeftes van die henne mag moontlik ook belangrik wees om in ag te neem.af
dc.description.sponsorshipNational Research Foundation (NRF)en_ZA
dc.description.sponsorshipProfessional Development Programme (PDP)en_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectBroilers (Poultry)en_ZA
dc.subjectBroilers (Poultry) -- Reproductionen_ZA
dc.subjectBroilers (Poultry) -- Weighten_ZA
dc.subjectDissertation (M.Sc.Agric. (Animal, Wildlife and Grassland Sciences))--University of the Free State, 2006en_ZA
dc.titleThe influence of body mass on production characteristics of broiler breedersen_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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