A critical analysis of the production and reproduction efficiency of Nguni cattle (Bos indicus africanus) in different geographical regions of South Africa

Abstract

Nguni cattle are known for their qualities of adaptability to harsh environmental conditions. Research has shown that this breed of Bos taurus africanus has evolved over the years and in the process developed resistance to difficult conditions such as tick burden and tick borne diseases, scarcity of food, high temperatures and humidity (Mukasa-Mugerwa, 1989, Schoeman, 1989, Maree & Casey, 1993, Kars et al., 1994, Collins-Lusweti, 2000a, Scholtz, 2005). The hardiness of the Nguni breed makes it an appropriate breed for farmers at any level i.e. communal, emerging and commercial farmer, as they vary in the purpose of keeping the breed. Nguni cattle are therefore a good breed for any environment, hence their being scattered all over Africa. Despite their adaptability qualities, the environment in which they are does affect efficiency of production of the Nguni cattle. The adaptability of the Nguni breed has been thoroughly researched and is well documented in many publications and books. Research is lacking on the effect of different geographical regions as determined by climate on the production and reproduction of Nguni cattle. This study addressed this hypothesis, hence non-genetic factors such as dam age, biome, bioregion, season and birth year were analyzed to test their effects on the production and reproduction of this breed. The effect of environmental conditions such as climate, expressed in seasons, and vegetation, expressed as biomes and bioregions, was tested by using GLM of SAS (2017), version 9.3. A total of 7 biomes were identified from the location of farmers, however breeders with the most animals were located only in the Savannah and Grassland Biomes. Within each of the two biomes, four bioregions were identified. The main factors assessed were age of dam in months, bioregion, season, calf sex and year grouping. Interactions between the main factors were also explored through analytical methods. Statistical analysis showed significant differences (P<0.0001) between the different geographical regions in terms of the productivity of the Nguni cattle. The age of dams significantly affected (P<0.0001) the performance of the Nguni cattle although this varied according to the different parameters. The effects were most significant in the birth, weaning, 12-month and 18-month weights of the calves in each bioregion as well as in calf and cow weights at weaning. The calf sex was found to be significant (P<0.0001) to the weights of the calves at all stages of growth, where male calves were heavier than the females in all main factors analysed, such as bioregions, seasons, year groupings and between breeders. Differences were also observed between the different bioregions within each of the two biomes. Cow efficiency was evaluated using 3 different equations, namely; calf weaning weight as a proportion of cow weight at weaning, percentage Inter-calving Period (ICP) as a proportion of ICP as per Nguni breed standards and calf weaning weight corrected to 205 days as a proportion of livestock unit (LSU). . The equations utilized the cow and calf weights at weaning as well as the ICP of cows in the study. Irrespective of the evaluation method used, the best cow efficiency was observed in the Eastern Kalahari Bushveld bioregion of the Savannah biome. In the Grassland Biome, the best cow efficiency was observed in the Drakensberg bioregion. The data was collected over 20 years, which were grouped into 5-year periods. Significant differences were observed between year groupings in performance of calves, with best performance observed in year grouping 1 (1990-1995) and year grouping 4 (2005-2010). According to the available weather data, in year groupings 1 and 4 there were good rains received both in the Savannah and in the Grassland Biomes. This partly explained the good performance observed in this study. Seasonal effects influenced the performance of calves and cow weights at weaning. Of further interest was the difference in performance of the Nguni breed, not only as affected by the environment but also due to the breeder or management factors. The breeder effects were evident through different calf weights at various growth stages, different cow weights at weaning and varying ICP of cows of the breeders though farming at the same bioregion although this was not easy to quantify, as it would mean having a broader knowledge and understanding of each breeder’s management style. In this study, cow performance based on cow weights at weaning and ICP was significantly affected by the environment and by the management of breeders. Similarly, calf growth expressed as calf weights at different stages of growth namely birth, weaning, 12- and 18- months differed significantly within and between bioregions as well as between the different breeders. This study established that the production and reproduction efficiency of the Nguni cows which are renowned for their hardiness and adaptability to harsh environments (e.g. semi-arid and arid regions in southern Africa), are affected by the environmental factors.