Sustainable crossbreeding systems of beef cattle in the era of climate change
Beef cattle are unique, because they not only suffer from climate change, but they also contribute to climate change through the emission of greenhouse gases (GHG). Mitigation and adaptation strategies are therefore needed. An effective way to reduce the carbon footprint from beef cattle would be to reduce the numbers and increase the production per animal, thereby improving their productivity. Sustainable crossbreeding systems can be an effective way to reduce GHG, as it has been shown to increase production. There are a wide range of different cattle breeds in South Africa which can be optimally utilized for effective and sustainable crossbreeding. This paper reports on the effects of crossbreeding on the kilogram calf weaned per Large Stock Unit (kgC/LSU) for 29 genotypes. These genotypes were formed by crossing Afrikaner (A) cows with Brahman (B), Charolais (C), Hereford (H) and Simmentaler (S) bulls and by back-crossing the F1 cows to the sire lines. A LSU is the equivalent of an ox of 450 kg with a daily weight gain of 500 g on grass pastures with a mean digestible energy (DE) content of 55% and a requirement of 75 MJ metabolizable energy (ME). Crossbreeding with A as dam line increased the kgC/LSU on average by 8 kg (+6%) - with the CA cross producing the most kgC/LSU (+8%) above that of the AA. The BA dam in crosses with C, H and S, increased kgC/LSU on average by 26 kg (+18%) above that of the AA dam, with the H x BA cross, producing the most kgC/LSU (+21%). The BA, CA, HA and SA F1 dam lines, back-crossed to the sire line breeds, increased kgC/LSU on average by 30 kg (21%), 21 kg (15%), 19kg (13%) and 26 kg (18%) above the that of the AA, respectively. The big differences between breeds in kgC/LSU provide the opportunity to facilitate effective crossbreeding that can be useful in the era of climate change. From this study it is clear that cow productivity can be increased by up to 21% through properly designed, sustainable crossbreeding systems, thereby reducing the carbon footprint of beef production.
Keywords: Carbon footprint, cow productivity, kilogram calf, production systems