EDIT: This post was typed whilst the two preceding posts were being made, therfore prior to reading them.
Brown Cow, A quick response. I totally agree with your second paragraph. I do not know enough to comment much on your third/final paragraph, but, foetuses and placenta size are relative to the dam's size. A Shetland mare will give birth to a foal sired by a Clydesdale. The problem in goats (possibly researched more because there are more) is that mixed sex twins that share one placenta have their umbilical cords in the same placenta. Consequently there is a mix of blood between them.
Your last sentence echoes my own questions in my previous post. It is generally accepted, in goats, with a little doubt, that one or both parents carrying (born with) horns, will not produce an intersex. I would like to know whether it is the same in sheep and cattle.
EP90, You make some very bold statements. This is a friendly site, and I like to keep it that way. How do you know you have worked with more cattle than other people? I do note that you are prepared to admit you are still learning. So are we all. Nobody disputes f/f twins have no problems. Your 50/50 sharing of hormones is not correct either. W'n'w, who I would guess has perhaps a wee bit more experience than yourself, has already told us he has bred from heifers in mixed sex pairs, and is quite happy to do so. I have had many sets of twin lambs and twin kids, and always, and I mean always, the combined value of the pair has exceeded that of any single - commercial, not stud, values. At the same time, the twins born by the Sydney Royal Supreme Champion Angora Buck that I owned brought a lot more individually than singles by him, because the buyers wanted twin bearers in their future breeding.
How much longer do you reckon a cow or ewe will live if it only has singles instead of twins? How many offspring are you going to sell from that animal? Value your singles, and value the twins. Add on any additional feed you deem necessary for twin bearers. What is the difference? I have had a fair supply of triplets in my time too (never quads) and the additional care and attention has been little in financial terms. It does make financial sense. I have never, ever, had a case of milk fever or twin lamb disease. Why do you think that is?
I do not know who taught you, but breeding for twins, especially in sheep, has been advocated by better men. Yes, I am prepared to say that. I will start with and name only Professor McGregor-Cooper, who did not teach me, but who I knew.
You can read on my profile what I have done, and where I have been. From memory w'n'w gives a bit of information about himself too. Would you care to tell us, purely for comparative purposes, how much experience you have of running your own place, and the stock you have had? If you match us, then I am prepared to accept the sort of blunt statements you make and then debate them. Failing that, it might be better if you modified things slightly and put forward opinions. Everybody has opinions. We are all allowed to have them. Give some reasons why you think something is so, and you will probably find that people on this forum agree with you. Perhpas not in totality, but at least in part. That way we all learn.
ALSO EDIT: EP90, Your last post, responding to w'niw, and part of the questions I have put above, is an effort to justify a stance you have already taken. Please xplain your figures in sufficient detail that readers can assess how much per head you are cliaming it costs to have twins rather than singles, and why you would have breeders in poor condition. Also why you would lose 40% of youngstock. What are your predators and where are you farming?