woolpuller wrote:Back in 1970 Dr Charles Parker had two curves on the board in his lecture. He showed that if the ewe lamb didn't lamb as a yearling but was held to lamb as a two year old first, the ewe lamb would put more money into the flock lambing as a yearling. The first time two year old would never, in most cases, do the same.
and I will contest that. First, to my knowlege, the amount of research on this is preciously limited both in repetition and in scope. There can be vastly different outcomes depending upon management system.
Imagine your typical university farm flock research facility....all sheep are fed alfalfa hay and corn, the infection rate of OPP is relatively high, so many ewes are culled by 5 years old. Ewe lambs get too fat if not bred to lamb at 12 months old. So yes, under those conditions, it would seem that a ewe that lambs at 12 months of age is going to make more money than one that lambs at 2 years of age, largely because the life span in the flock is short, so the cost of being open that first year is a large % of the total.
Now compare that to a more extensive flock, where ewes are held open until 2 years of age, but will remain in the flock until an average of 7 years. IME the 4th, 5th, 6th, and 7th year are among the most productive years. Now the playing field levels out quite a bit and holding the ewe open is no longer a 'cost'.
I arrived at this conclusion after noting (as I was moving toward an all forage system) that my two year old ewes were unacceptably thin, and remained so through their third year. I also noted that (as I moved toward an all forage system) that the number of lambs born to two year old and three year old ewes was dropping. Obviously the body condition and lambing performance were tied together, and we previously compensated for this by purchasing grain in order to sustain that level of production. It became clear to me that if I am to lamb my ewes at 12 months of age in an all forage system, that I was going to have to manage the two and three year old ewes better as well as the yearlings. This of course entails importing grain or higher quality hay.
Over the course of 4 years I tried a variety of ways to manage ewe lambs through the first 24 months. Bottom line was that these ewes needed to learn how to eat snowballs and mature 'upland' hay at some point, and when ever that point of learning occured I could expect them to have trouble holding body condition. So what was happening was that even though I could compensate and feed the ewe lambs better hay, they eventually had to adjust to our mature ewe winter feed program. then it dawned on me the most inexpensive time to go through this adjustment was as lambs. Leave them open, let them sort it out the first year, and they would be ready to go to town as 2 year olds.
Ever since I made that change our two and three year olds have been producing 40% more lambs, and do so without skipping a beat and without having to feed them separately.
Bottom line is, you buy those extra lambs produced in early production. I think if the early research was to have put a pencil to the extra cost entailed the conclusion would be different.