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'n Vergelykende produksie-evaluering van die Nguni in intensiewe en ekstensiewe stelsels

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dc.contributor.advisor Schoeman HAW, Dr en
dc.contributor.author Lepen JM en
dc.date.accessioned 2016-09-26T06:26:35Z
dc.date.available 2016-09-26T06:26:35Z
dc.date.submitted 1988 en
dc.identifier.uri http://hdl.handle.net/20.500.11892/173878
dc.description.abstract The growing interest in the Nguni and the need for reliable knowledge with regard to the product ion potential of the breed led to the investigation of the following aspects. Firstly, the development of puberty in the Nguni is evaluated with these of Bonsmara and Drakensberger heifers in an intensive system (feedlot conditions) and secondly, with these of Nguni heifers in an extensive system (natural sweetveld grazing). The Nguni heifers in both systems were mated after puberty was reached after which a production evaluation was done. As the Nguni was unknown to breeders in general the origin is briefly discussed and a description of the breed is included. In addition, the historical development of the Bartlow Combine Nguni herd is officially recorded while a full description of the Bartlow Combine Breeding Station as well as herd management, is given. The various components of herd fertility are discussed with special reference to the present reproductive performance of the Bartlow Combine Nguni herd and the means to further improve the reproductive efficiency. In the first section of this study the effect of breed and nutritional level on the development of sexual maturity is dealt with. Under intensive feeding conditions Nguni heifers reached puberty at a highly significant earlier age (349,91 days) and lower mass (238,23 kg) as compared with Drakensberger- and Bonsmara heifers. At puberty the Drakensberger heifers were slightly younger (407,21 days) and lighter (298,71 kg) than the Bonsmara heifers which were 418,96 days old and with a mass of 341,39 kg. This difference was insignificant. Under intensive ad lib feeding conditions Bonsmara, Drakensberger and Nguni heifers gained 1 080-, 870- and 760 g per day respectively from weaning to the attainment of puberty. In the same period Nguni heifers consumed significantly less feed (326,8 kg) compared to the Drakensberger (780,27 kg) and Bonsmara heifers (1 1 51,27 kg). The difference in efficiency of feed conversion between heifers of the various breeds were insignificant. At puberty the Nguni heifers were the smallest while the Drakensberger and Bonsmara heifers had approximately the same stage of structural development. Nutritional level undoubtedly had an effect on development of sexual maturity. The group of Nguni heifers which were under intensive feeding conditions, maintained a highly significant higher ADG, attained puberty at a highly significant earlier age (344,51 as against 399,89 days) and on a slightly though insignificant lower mass (237,27 as against 234,85 kg) Both groups attained puberty on the same size. In the second section it was concluded that, even with a restricted mating period, Nguni heifers could be successfully mated under an extensive system (natural sweet- veld grazing) at the age of 13 to 15 months in order to calve for the first time at 24 months. Calving percentages of 73 and 76 % were respectively achieved under intensive and extensive systems, while an average reconception of 90,5 % was achieved in both systems. The indication, however, is that selection for early fertility is practically possible and that there is merit in the application of such a practice. No cases of dystocia were experienced, Firstly, it means that the average birth mass ( 24 , 9 kg) of calves from cows in the intensive system is still within the limits and secondly, that all the heifers had attained sexual maturity at the time of mating .The birth ratio of both systems was 8,1 % on average. Cows in the intensive system had weaned calves that were insignificantly heavier than calves from cows in the extensive system (164,66 as against 153, 63 kg). Likewise the weaning mass ratio in the intensive system was insignificantly higher than in the extensive system (47,14 as against 43,46 %). The heifers that were on a high level of nutrition (intensive system) during puberty development had a significant higher cow efficiency index. Mortality of calves from cows in the intensive system were somewhat higher (16,67 as against 13,04 %) than those of calves from cows in the extensive system while weaning percentage was slightly higher in the extensive system (74,07 as against 66,7 %). en
dc.language Afrikaans en
dc.subject Animal production en
dc.subject Agriculture en
dc.title 'n Vergelykende produksie-evaluering van die Nguni in intensiewe en ekstensiewe stelsels en
dc.type Masters degree en
dc.description.degree MSc(Agric) en

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