Estimation of the inter-annual marginal value of additional feed and its replacement cost for beef cattle systems in the Flooding Pampas of Argentina

摘要

The effects of climate variability are projected to increase in the future threatening the expected outcomes of grazing-based animal production, feed use efficiency, and development of sustainable farming livelihoods. The identification of profitable farm management strategies to overcome critical inter-annual feed supply deficits is a worldwide management problem for grazing-based livestock systems and such information is essential for designing resilient feed-bases against climate variability. Increasingly, beef breeding herd (cow-calf) farmers in the Flooding Pampas region of Argentina have added backgrounding enterprises to deal with inter-annual system risks, but the impact of adopting such livestock managements under different forage growth patterns has not been widely investigated in the region. The aims of our study were to explore the marginal value of feed (MVF; it quantifies the economic value of an extra kg DM or MJ of metabolizable energy) in a representative beef cattle farm from the Flooding Pampas region. By combining this variable with the replacement cost method, different feed alternatives available for farmers to increase feed-on-offer were compared, under climate and price variability. The feed scenarios were baseline [unchanged herbage mass accumulation (HMA)] or with an extra 10% of the annual HMA in different seasons (summer, autumn, winter, spring or all year around), within a full range of beef cattle systems (stocking rates and steer/cow rates with different target market liveweights for steers and heifers). These scenarios were tested by integrating forage, livestock and economic models in series. Drier years reached higher MVF, and cumulative curves showed greater absolute values and probabilities of obtaining a higher MVF in winter or spring, and lowest in summer. The backgrounding management alternatives provide opportunities to increase the MVF (by up to 20% >0.09 US$ per extra kg DM added in winter at 0.55 cows ha(-1) with a 0.4 steer/cow rate), enabling the purchase of high-quality forages (>0.07 US$ kg(-1) DM). However, high stocking rate and grazing intensity (>0.6) may reduce the inter-annual farm performance (LW sales ha(-1) and profitability). The framework developed in this study has provided new insights for diversifying into the use of complementary forage sources in the farm feed-base to improve farm resilience against climate and price variability in the Flooding Pampas of Argentina.