The International Standard
This shows the international letter system & its corresponding year.
*Note that I, O, Q and V are not used.
A1969 U1986 N2003
B1970 W1987 P2004
C1971 X1988 R2005
D1972 Y1989 S2006
E1973 Z1990 T 2007
F1974 A1991 U2008
G1975 B1992 W2009
H1976 C1993 X2010
J1977 D1994 Y2011
K1978 E1995 Z2012
L1979 F1996 A2013
M1980 G1997 B2014
N1981 H1998 C2015
P1982 J1999 D2016 (this year's calves!)
R1983 K2000 E2017
S1984 L2001 F2018
T1985 M2002 G2019
We also use a different colored tag for every year of birth. This is simply another aid to allow us to identify a cow at a quick glance. Sometimes you may only be able to see the number on the tag because of long hair, but if its orange you know that is likely a 'B' cow, for example. It is probably over kill (and does make for a LOT of extra tags always hanging around in every color) but it does work well for us.
This is where I think we differ. We tag our calves within 48 hours of birth. Because we cull cows for poor behavior we generally have a very tame herd that allows us to grab their calf and insert the appropriate tags while the mamma cow watches. Of course there are always those cows that snap after birth, so while it generally works well there is always some risk involved.
We give our calves their mandatory CCIA RFID tags in one year (left) and their management tag in their right year. We however don't give them the letter that corresponds with their year of birth (this year would be D's). Instead, we give them the same management tag as their mammas. This allows us to always know which calf belongs to which cow, if they are missing a calf, if that calf has adopted a new mother, etc. And because we tag them ASAP after birth, we always know which pairs go together.
Reusing Tags & Saving Money
After weaning, we take the tags in the house, wash them in soapy water to remove any old dirt and use a knife or pen to pop out what's left of the old button. We then use a tag pen to trace over the existing letter and number to make sure it is vibrant and readable for the next year.
*These are the actual costs of tags and buttons we purchased in 2015. Tax not included.
Large Allflex 2 piece tags/buttons: $30.44/ 25 tags & buttons ($1.22/head)
Allflex buttons: $14.59/ 25 buttons ($0.58/head)
Savings: $15.85/ 25 head ($0.63/head)
For a herd that produces 100 head of calves continuously, you would be saving $63.40 per year (or $0.63/head). Now that doesn't sound much, and it really isn't, but 63 bucks is 63 bucks in my opinion. My father in law loves to say that when you are young, you trade work to save money, and when you are old you trade money to save work. Clay and I are still young so I think we will continue to take the extra few minutes to remove tags, wash them and reuse them each year, at least for now.
Note: We have a very low tag loss rate in calves. In 100 head, we might lose one per year, if that.
Pros/Cons of Our Tagging System
For the calves being sold to market, I think it would be fair to say there is some stress on weaning day and adding an additional few minutes in the chute trying to wrangle a tag out of their ear likely adds to it. However, I don't know how much stress or how much shrink that would equate to, and if it would be enough to cancel out the savings from reusing tags.
The other option I see a lot of producers use is to tag at branding rather than at birth. I am not particularly fond of this method just because it is hard enough to know which calf goes with which mother when they have corresponding tags. Without tags for a few months before branding would always make me worry I have the wrong calve/cows matched up. This would wreak havoc on my record keeping system as my data would no longer be reliable. If a cow lost her calf and adopted another (which most certainly happens), and I use the adopted calf's data as that cow's progeny, I could have very skewed results as to the genetic characteristics that mother throws.