Productivity of South African indigenous Nguni goats possessing Synergistes jonesii bacteria on Leucaena Leucocephala-grass and natural pastures.
The main objectives of the study reported in this thesis were to investigate the cause of poor conception and high pre-weaning kid mortality rates among South African indigenous Nguni goats (SAING) maintained on Leucaena leucocephala-grass pasture (LGP), and the potential of natural pasture (NP) and improved pasture (LGP) for the productivity of the mimosine-susceptible SAING breed after receiving dihydroxypyridone (DHP)-degrading rumen bacteria (Synergistes jonesii) via animal-to-animal transfer. Seasonal variation in forage quality and mimosine contents of two Leucaena leucocephala varieties, detection of S. jonesii from rumen digesta, effects of feeding Leucaena foliage on semen quality, grazing activities and blood metabolite profiles during gestation and reproductive performance prior and post kidding were evaluated. Aspects relating to reproductive performance prior and post kidding, colostrum and milk constituents, growth performance and blood profiles of weaned and unweaned kids, dams-to-kid transfer of S. jonesii, protein and energy requirements of the SAING kids were also examined. Cultivar Cunningham was better suited for the location ofthe study than cv. Spectra because it was available during ten months of the year compared to the six months of cv. Spectra availability. Growth performance, reproductive performance and overall productivity of SAING maintained on LGP were better than those of their counterparts on NP. Benefits of LGP during gestation include higher body weight gain of does, higher incidence of twin multiple births and higher birth weight of kids compared to values on NP. Higher milk yield, earlier return to first postpartum oestrus and better pre-weaning growth of kids relative to values obtained on NP, were the benefits of maintaining SAING on LGP during lactation. Over the entire study, conception on LGP treatment compared favourably to that on NP. Feeding Leucaena foliage did not have any detrimental effect on semen quality and fertility of the SAING bucks. Feeding LGP as gestation or/and lactation feed had no detrimental carry-over effect on the post kidding reproductive performance of SAING does and kids. The kids were also able to acquire S. jonesii from dams via animal-to-animal transfer.