Herd efficiency can be determined easily enough by measuring feed used over a given time divided by pounds of fryers harvested.
But your question is how to select for feed efficiency.
If I said use the herd average feed efficiency and compare a particular animal's pounds of fryers harvested it doesn't accurately translate. This is because that particular animal and its offspring may be heavy eaters.
On the other hand it IS possible to use the converse to cull out animals that are not meeting herd averages. This again is not absolute since you possible could have a doe that is a minimal eater and produces animals that are slim eaters. However, I think you can make pretty good general assumptions that within reason a doe will consume 3-4% of her body weight daily non-lactating and your bucks will do likewise whether or not they are good producers. Will you agree that a non producing doe and a non producing buck is killing your feed conversion? I mean, after an animal is grown their is no feed conversion because they cease to put on weight! If this is true then you can see that it is the growing rabbits, the young, that bail out the does and bucks. Additionally, it is the 0-8 week olds that are bailing out every other animal. (After about 9 weeks animals start to eat more feed and gain slower thus lowering your feed efficiency.)
I know I'm answering this in a roundabout way but I hope I am helping.
Okay, selection of animals for feed efficiency given the above means selection first by the process of elimination - culling those animals that are not producing enough young to bail them out of their own static feed use. Cull immediately those does animals that are non-producers. Second, cull bucks whose records indicate they have smaller litters than herd average. Third cull does that have litters that fail to grow to an appropriate weight in 8-9 weeks. Fourth, look closely at litter size and number of kits raised out. If your herd average is 8 kits per litter and seven raised out then cull does that average less than 8 per litter or less than 7 raised out. Remember, aside from the runt, it is the litters and young that are bailing out the adults to help your feed efficiency. Typically increase number and size of young and your efficience can't help but increase.
After you do the above culling the animals left are your selections for feed efficient animals. They are the winners by default!
I have read elsewhere that every rabbitry should set goals every year based on last year's records. Determine what your stats are now and set goals for next year. This will mean eliminating those rabbits that are not meeting the herd averages. The cream of the crop will rise to the top.
Hope this helps or at least kick starts some conversation and ideas.
Thank you so much for your reply: I hate to shut you off by saying that wasn't quite what I was looking for. I am being more specific than overall *facility* efficiency, but your appraoch to that issue is correct in my opinion.
I realize that we can compare overall efficiency by the approach you have taken. But to really begin to change the efficiency of feed utilization per pound of product, don't we need to feed each animal individually and compare that animals' rate of gain to the feed it actually ate? I realize that we can get a "Litter" efficiency in the manner you have described, but to maximize progress in feed efficiency, wouldn't we have to feed animals separately?
Yes, I would suggest you independently feed some
prospective breeding stock.......especially the bucks.
For example, if I have litters marked for potential
additions to my herd, I would need to take those
litters and perform side by side feed testing to determine
growth rates and feed conversions. Save your bucks
and does from the most efficient with the best growth
and send the others to market. If you find it too time
cosuming to test does and bucks, then concentrate on
the bucks. By keeping good records, you will certainly
see that some "lines" are just better at feed conversion
just as some lines of does are better milkers.
It takes time but improvement will be noted!
(Experience speaking here!)
If someone were to invest the time into developing several generations of rabbits individually fed to determine feed efficiency, would there be a market for them? I am assuming that few people have replied to my questions, because no one is actually doing much about feed efficiency, other than managing overall system efficiency, and saving replacement animal from litters that seem to use less feed than the rest.
Yes and no... to both your question and assumption!
Yes, there will always be a market for a line of feed efficient rabbits, as this was proven quite recently by a line of Satins which were developed for this purpose. Unfortunately, there are problems, as many simply "assumed" that *all* Satins were more feed efficient, rather than just that one specific line (my own Satins were eating me out of house and home!). Secondly, just as with pasteurella-free rabbits, KEEPING them that way after purchase is the real trick! This involves using the same feed, same feeding schedule, and not breeding with other lines known not proven to be as feed efficient. As always, haphazard breeding destroys a lot of good work and good intentions. Of course, this would have no real bearing on your own claims, but rather, on the expertise of your customers.
The reason why more people are not concentrating on this aspect has to do with individual priorities, wherein most will concentrate mainly on improving growth rates, instead. Culling for too many priorities at the same time can literally wipe out an entire herd, wherein feed efficiency might be culled due to poor weight gain or some other priority. I'm sure you get the idea. Combined with the 6-6-6 curse of the rabbit meat industry, they just never get around to working on feed efficiency before getting out of rabbits. Improving one's herd in all aspects is a life-long on-going project that never ends.
I hope this answers your questions.
Professional Rabbit Meat Association
because no one is actually doing much about feed efficiency
Many commercial breeders are doing a lot about their
feed efficiency. Rabbit Production states that there is a positive genetic relationship between rate of growth and feed efficiency. Even without testing of potential sires and
dams, it would seem that those producers would be making progress in a practical labor saving manner when they select the heaviest of the litters as additions to the herd.
that seem to use less feed than the rest.
In my case, *seem to* is not an accurate description.
The results of a properly managed feed test doesn't
leave the selection to chance.
As Pat alluded to in her reply, creating a "feed bias"
is a real possibility. Now....if you changed feed frequently
and validated the results in a *cross herd analysis*,
I think you might have some customers!
What was the genetic correlation between FE and gain reported by Cheeke in Rabbit Production? I haven't read the book for some time. Also, if there was a genetic correlation reported between those traits and mature size could you please tell me what it is?
I don't think it was in "Rabbit Production," but rather, "Rabbit Feeding and Nutrition" by Cheeke. I'm still plowing my way through this book packed with charts, but I did find where he stated on page 172:
"No set quantity of feed that is satisfactory can be stated, because the amount necessary for maintenance will depend on the energy content of the diet and the size and the breed of the animals."
Come to the chat tomorrow evening, as we *will* be discussing this very subject with Dr. Mark Grobner.!
Professional Rabbit Meat Association
Certain rabbits have been bred for differnt things. The New Zealand White was bred to be a meat rabbit. The initial reasons for developing this breed was to establish a rabbit that would grow faster to a larger size in less time on less feed. Therefore, I feel that if you are raising rabbits to sell as meat, this breed is probably the best overall performer available. The Californian and Florida White are also good meat rabbits. The Californian was used in the development of the New Zealand and is basicaly physiologically the same rabbit, it has many of the characteristics of the NZ. They grow fast on less feed. On average it takes approximately 3 pounds of feed to produce 1 pound of meat on a New Zealand. Hope this helps a little. Thanks
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