Just chatted with a few sheep friends, suddenly came up with such a question: to be honest, this problem seems to be relatively simple, but in fact it is very complicated to calculate, it not only tests our mathematical calculation ability, but also examines our actual sheep breeding experience and technology. Next, I will combine my actual experience in breeding small-tailed cold sheep to do this arithmetic problem.
Explain in advance: excellent small-tailed cold sheep breeding ewes can do two litters a year or three litters in two years, the number of lambs per litter is 2 to 5, under better breeding conditions, the survival rate of lambs can reach more than 85%, and the first fetal ewe produces a single lamb. According to my experience in breeding small-tailed cold sheep, most breeding ewes are three litters in two years, and two breeding ewes a year account for less than a quarter of the flock, but this is absolutely there, and there is nothing to question. Recently, I have seen many friends question the authenticity of the small tail cold sheep two births a year, they are based on the pregnancy period of the sheep to calculate the theoretical value, this is not accurate, only the breeders who have really raised this breed understand the most clearly.
First of all, it is impossible to achieve a 100% lambing rate by breeding ewes in captivity, and from the actual effect, the lambing rate of more than 85% can be achieved is almost perfect. If a small-tailed sheep breeding ewe produces an average of 3 lambs per year, with a survival rate of 85%, then the number of lambs in the first year is: 3×85× 0.85 = 216.75. You should note that this is the combined number of male and female lambs, how many male lambs are there, how many female lambs are there, and we cannot give detailed data. Following the reproductive principle of "leaving the male and leaving the mother", it can only be divided in half.
Secondly, the breeding law of the "donkey rolling" style should also determine its number according to the reproductive characteristics of the small-tailed cold sheep. By the second year, the first 100 small-tailed sheep breeding ewes could still produce 108 small lambs, and the number of breeding was fixed. However, the first year of 108 small lambs wait until 7 to 8 months before they can become pregnant and lamb, this batch of sheep belongs to the first birth of ewes, the reproductive rate is not high, the number of lambs per birth is 1 to 2, and then remove the halving of the small male lambs, then the number of lambs that can be used to breed is between 60 and 70.
Finally, in the crucial third year, the population size also increased step by step, and the scale of the population also increased step by step. If all the 100 small-tailed sheep breeding ewes in the early days are alive, then they are the "heroes" of our farmers, who have made great contributions to the expansion of the population, and the rest of the sheep belong to their "disciples". The number of breeding ewes in this period is a bit large, let me calculate in detail: the first 100 breeding ewes are primitive capital, they can continue to produce 108 small lambs; the first year of 108 small lambs can produce 115 lambs in the third year; the first year of 108 small lambs in the second year give birth to 60 to 70 mother lambs; and by the third year, these 60 to 70 mother lambs can give birth to 30 to 40 mother lambs.
Of course, this number is only a reference number, in fact, if it can be expanded to 500 stocks, it is already a very successful professional sheep farmer. Again, as the old saying goes, if sheep farming is not actually practiced, sitting at home and relying on the sheep data obtained by the predecessors to analyze and calculate, basically will not make much sense.