The Breed Back Blues-Avoid Calving and Breeding Problems

"Summer time and the living is easy"; or so the song says. Most folks in the farming community might disagree with planting just finished and fencing and haying upon us. It seems like just one more job, but we might want to be keeping a close eye on activity out in the breeding pastures or we might just be singing the blues come fall - The Breed Back Blues!

Last summer is still reaching forward to play havoc with some of our cow herds. We all know last summer's rain made putting up good feed awfully hard, if not impossible. That meant many of our cows went through the winter on poor quality feed and were in lower than normal body condition come calving time. We saw some problems across the province with weaker, less vigorous calves, resulting from poor colostrum. Then, when we think we have the cows out to grass and all is well, there is one more problem cropping up from last year.

Those cows with a poor body condition score (BCS) at calving, will be slower to return to estrous and slower to settle to a pregnancy. So whether your bulls have been out for a bit, or just heading to the breeding pasture, now might be a good time to take a second look at those cows. What body condition were they in at calving? What condition are they in now? Is the pasture good enough to have them on a rising plane of nutrition?

Figure 1. The estrous behaviour shown here by this cow mounting a bull in late Fall is a clear indication that she is not pregnant, at a time she should be.

Numerous studies have shown that only 60-70% of cows, which are thin or in moderate shape at calving, will cycle 90 days out when you want to start breeding. That means 30% or more of these cows will not achieve a 365 calving interval due to them skipping at least one oestrous cycle. One cycle missed is 21 days times 2.5 lbs/day calf gain, resulting in a calf 50 lbs lighter for sale in 2010.

The Tables below, 1 and 2, are adapted from work by William E. Kunkle from the University of Florida. He obtained BCS data from beef herds in Florida, Texas and Oklahoma. Kunkle examined the effects of low BCS in a beef herd (poor conception rates, longer calving interval and not milking to potential) and determined the difference in yearly income per cow. Admittedly, this chart is using lighter birth weight, ADGs, and weaning weights than many Ontario herds exhibit. As well the $1.00/lb is low but certainly illustrates the costs associated with cow herds in poor body condition.

Figure 2. A cow displaying signs of normal estrous will catch the breeding bull's attention

Table 1. Relationship of parity and body condition score to pregnancy rate, %^a.

^a Rae et al., 1993; Body condition scored at pregnancy testing
^b Parity is the number of calving opportunities, present age minus age at first calving (years)
^c Body condition scored at pregnancy testing from 1 to 5, 1.5=thin, 2=borderline, 4=moderate
Note: BCS adjusted from original data to Canadian 1- 5 system for Tables 1 and 2

Table 2. Relationship of body condition score to beef cow performance and income.

^a Pregnancy rates averaged across trials when scored at calving, breeding, and pregnancy testing
^b Calving interval from Figure 3 in original report.
^c Weaning age is 240 days for cows in body condition scores 3 and decreases as calving intervals increase.
^d Daily gains based on observations.
^e Calculated as calf age times calf gain plus birth weight (70 lb).
^f Average auction market price for similar weight calves during 1991 and 1992.
^g Calculated as calf weight times calf price.
^h Calculated as income/calf times pregnancy rate times .92 (% calves raised of those pregnant).
Note: BCS adjusted from original data to Canadian 1- 5 system for Tables 1 and 2

If you know your cows were feed stressed this winter, watch them now to see how many are cycling or breeding. Consider feed supplements if they are still very low in condition or at the very least make sure they are well taken care of in the mineral and vitamin category. Take a good look at your cows and act now if need be, to prevent the "Breed Back Blues" being your theme song this fall with open cows or more importantly next year with very late calves!