Fall is rapidly approaching and all cow-calf producers need to access the body condition score (BCS) of their herd. Spring-calving cows are nearing weaning time and the fall is the most economical time to put weight back on. Now is also a key time to manage BCS score in fall-calving cows. Most realize the link between body condition score and reproductive rate but what is the economic impact of allowing BCS to decline? Each year producers faced the decision of how much money should I put into my cows? Can I afford to feed them? So, what is the cost of letting your cows get thin? What is more cost effective; reducing costs by limiting nutrition to your cows and living with reduced reproductive performance or feeding your cows to perform?
Let's use a real world example. The farm we will discuss consists of 100 fall-calving cows. The average body weight of these cows was about 1300 lbs. at a BCS of 5. These cows calved in good condition, averaging a BCS of a strong 5. However, lack of rain resulted in limited pastures and the producer began to feed hay approximately September 1st, which coincided with the onset of calving. The hay was below average in quality (TDN of 48, CP of 7%). Money was tight for this operation so they made the decision NOT to supplement these cows. Making the assumption that these cows were average lactating cows and that they would consume about 27 pounds of hay (as fed) daily, the hay provided only 82% of their maintenance energy needs and would result in a loss of one BCS in about 57 days. This producer decided to synchronize and AI his cows. On November 21st when the timed AI was performed, the average BCS had decreased, as predicted above, averaging a strong 4. Remember each BCS equals about 75 pounds so these cows were losing weight rapidly. After the insemination, the bulls were turned out for 60 days then removed. The cows were diagnosed for pregnancy about 40 days after the insemination and their average BCS was a weak 4 so the cows likely lost another 30 pounds or so of body weight. Reproductive performance was terrible as only 29 conceived to the AI, 31 conceived via natural service, and 40 were OPEN!
This example may seem exaggerated but this scenario actually occurred on a farm and is a real-world example of improperly managing body condition score. The question then becomes which was the more economical management scheme; no supplementation and reduced reproduction or supplementation to meet nutrient needs. To help determine this let's first look at our losses. In the above scenario, 40 cows were examined as open. Of these, let's assume 7 would have been open regardless so 33 calves were lost due to the reduced input management. Let's say these 33 calves (17 steers, 16 heifers) would have weaned at 525 pounds (550 for steers, 500 for heifers) so we lost 17,350 pounds of product. If we would have sold these calves last week they would have averaged about $1.57 for the steers and $1.44 for the heifers. Our lost income would be about $26,200 (17x550x1.57=$14,680 and 16x500x1.44=$11,520).