– Grady Ruble, SDSU Extension Cow/Calf Field Specialist
Purchasing or raising replacement females represents a significant investment for cow/calf operations and the impact may be felt for years after. To aid in the decision process, we are building a Microsoft Excel based decision aid that will allow producers to compare two business models: developing home-raised replacements or purchasing pregnant crossbred replacement females for a terminal sire system. Our decision aid, which will be available spring 2019, approaches the situation from a different perspective than others in recent years. Instead of only maximizing weaning weight, the focus is maximizing weight produced by the ranch. The idea behind this concept is if one chose not to develop heifers those feed resources could instead be devoted to more producing cows. That same ranch could then purchase bred replacement heifers and ultimately produce more pounds of calf on the same resources as a ranch that is developing home raised heifers. Consider the objective of modern-day corn farming. The objective is not to maximize kernel yield from each corn plant, but rather kernel yield from the entire field. The production metric for corn farmers is bushels per acre. A cow can be thought of as a corn plant, she harvests the nutrients from the land and produces a calf. Corn farmers don’t use bushels per corn plant as a production metric, why should pounds per cow be used in the beef industry?
The objective of this decision aid is to provide producers an additional metric to determine if raising replacement heifers is the most efficient use of ranch resources. Input variables include: number of cows, replacement rate, weights of cattle marketed, expected prices received/paid for: calves, cull cows, and bred heifers. According to input variables, net energy devoted to producing cows and developing heifers is quantified. Total net energy is the sum of that devoted to cows and heifers, respectively. The decision aid then calculates how many cows are currently displaced by developing heifers. Lastly, the decision aid is also unique in that additional performance attributable to heterosis in the purchased replacement heifer system is accounted for.
Heterosis is the key to maximizing production efficiency through a combination of individual and maternal heterosis advantages. The combined effects of maternal and individual heterosis yields a 20-28% increase in pounds weaned /cow exposed /year (Spangler, 2007; Weaber, 2015). In a crossbreeding system where F1 females were mated to a terminal sire of a different breed, the observed advantage was 23.3% (Gregory et al., 1965; Cundiff et al., 1974). In this system 8.5% of the heterosis advantage was attributed to individual traits (Gregory et al., 1965) and 14.8% was attributed to maternal heterosis from the crossbred cow (Cundiff et al., 1974). This demonstrates the importance of both maternal and individual heterosis, namely the benefit of the crossbred cow.
Purchasing bred crossbred females for use in a terminal sire system is an attractive solution as it offers the simplicity of managing a straight-bred herd, while simultaneously maximizing herd heterosis. The upfront cost of purchasing bred crossbred heifers can sometimes be a deterrent but failing to maximize ranch productivity could be much more expensive. This decision aid will assist producers to visualize the costs associated with raising heifers and if those resources were reallocated to the mature cow herd how much they could afford to spend when purchasing replacement bred females.
In summary, the decision aid used to compare the two systems is rooted in biology. According to user input, the production potential of the operation is estimated and carrying capacity is calculated. Paired with economic conditions unique to each individual operation, the decision aid will hopefully simplify the replacement heifer dilemma.
- Cundiff, L. V., K. E. Gregory, and R. M. Koch. 1974. Effects of heterosis on reproduction in Hereford, Angus and Shorthorn cattle. J. Anim. Sci. 38(4):711-727. doi: 10.2527/jas1974.384711x
- Gregory, K. E., L. Swiger, R. Koch, L. Sumption, W. Rowden, and J. Ingalls. 1965. Heterosis in preweaning traits of beef cattle. J. Anim. Sci. 24(1):21-28. doi: 10.2527/jas1965.24121x
- Spangler, M. L. 2007. The value of heterosis in cow herds: lessons from the past that apply to today. In: The Range Beef Cow Symposium XX, Fort Collins, CO.
- Weaber, R. 2015. Crossbreeding Strategies: Including Terminal vs. Maternal Crosses. In: Proc. Range Beef Cow Symp. XXXIV, Loveland, CO. p 117-130.