On average, cull cows can produce 10-20% of the total revenue in a beef cow-calf enterprise. Increasing that value by just a third can improve overall ranch revenue by as much as nearly 6%. And as little as a 10% increase in net income from the sales of cull cows would nearly double the overall ranch profit margin.

Thanks to the availability of economical and plentiful byproduct feeds, feeding cull cows can add value to an animal that has otherwise held only salvage value. Cows with a higher body condition score, and more weight, optimize economic returns by delivering both a higher carcass value and a higher live value. Research shows cows on full feed for 28-56 days had higher carcass weights, which were due to an increase in carcass soft tissue, or lean, as well as carcass fat and not just gut fill.

Two feeding experiments were recently conducted on cull cows from the same herd in South Florida. Cows were similar in genetics and age in both years, and the diet provided 87.6% dry matter (DM), 14% crude protein (DM basis), and 79.5% TDN. It was fed ad libitum in self-feeders and composed primarily of soybean hulls, citrus pulp, cracked corn, wheat middlings, cottonseed hulls, cottonseed meal, molasses, tallow and urea. An ionophore was also included.

All the cows were dewormed on arrival with a generic ivermectin at label rates. In Year 1, half the cows received a growth-promoting implant on arrival. Carcasses were harvested in both years at a commercial beef processing plant in central Florida.

Year 1: As received, these 92 Brangus crossbred cows were uniformly thin — with an average body condition score (BCS) of 4.2. Cow body weights (BW) were obtained on Days 0, 56 and 90. Average BW on Day 56 was nearly identical to BW at the end of the feeding period, Day 90. From this, we concluded that long feeding periods, or days on feed (DOF), weren't necessary under these conditions and were actually costly since cows continued to consume feed from Day 56 to Day 90 and gained almost no additional weight.

Over the 90-day feeding period, implanted cows gained more total weight (259.7 lbs. vs. 230.5 lbs.) and average daily gain (ADG) was increased (2.9 lbs./day vs. 2.6 lbs./day), compared with un-implanted cows.

In addition, carcass value was increased by $249 when cows were fed for 90 days compared with selling them thin on Day 0. On average, feed costs were $230/head. The net result was a difference of $19/head — $722.8 (value of fed cows) minus $230 (feed costs) minus $473.8 (value of non-fed cows).

Year 2: On arrival, 95 Beefmaster and Brangus crossbred cows were uniformly thin (with an average BCS of 3.6). Based on the conclusion reached in Year 1 regarding DOF, cows were fed no more than 50 days. The ending BW for fed cows averaged 1,068 lbs., with fed cows gaining an average of 115 lbs. during the 48-day feeding period (2.4 lbs. ADG).

Meanwhile, carcass values differed by $152/head (harvested Day 0 = $531; harvested Day 48 = $682). Although some costs of feeding had increased from the previous year, especially fuel and thus delivery, we assumed the same feeding costs as in Year 1 — about $2.55/head/day. Since DOF were decreased, feed costs amounted to only $122.40/head. Therefore, the net result of feeding these cows for 0 days vs. 48 days was $28.60/head — $682 (value of fed cows) minus $122.40 (feed costs) minus $531 (value of non-fed cows).

These data indicate a monetary benefit from feeding cull cows a concentrate diet for 50-90 days. The true optimal and maximum DOF with regard to profitability may vary within that time frame, and it will likely depend on current conditions of commodity feed prices and cattle prices alike.

At minimum, cows should be implanted with an appropriate growth-promoting implant to maximize feed energy intake and promote the conversion to lean muscle and thus, final live and carcass weights. A complete and well-balanced diet should be provided and should include an ionophore to improve feed conversion.

Jeff Carter is an assistant professor at the University of Florida's North Florida Research and Education Center in Marianna.