Cow size

[rkaiser]

Roughing them through the winter hey. Is this not a way to build efficiency into your program? Not only do you bring down your feed costs, but you keep the heifer size down and thus her need to eat less for at least the first couple of years. Her mature size and weight may end up close to that of her mother unless you are making an attempt through genetic selection to bring down size. (ie. Size of Bull and his parents.)

Interesting in our little heifer pen. As I said this is the first group of girls that have seen no grain whatsoever. Have a cow with twin heifers in the pen with them. She is one of my top cows and I am spoiling her a bit to bring these twins on and bring up her condition. I take a bit of grain in the pen for her each morning and the cow eats on her own. The heifers don't know what grain is and are not even interested.

Breeding grass based cattle is not only genetic, but environmental as well. I predict that our bulls will look for grass and bloody well eat it to supply their needs for the rest of their lives. They moved out into the sloughs all winter long to graze while their hay feeder was full.

Randy

[cswilson]

It works on cows and horses too-there's alot to be said for just letting them grow up at their own pace. In as far as breeding stock goes-our little hay fed bulls are still working past ten years old in alot of circumstances. TRandy is right about cutting costs by running heifers a bit tougher-we have a couple 4H heifers every year for the last 12 years or so-they are treated better but don't last as long as the heifers that run out and lick snow. As far as horse I've seen more crippled up unsound horses from outfits that overfeed their young stock. We bucked a couple three year old studs this weekend that wintered on straight hay-they were hard,fit and were 3-0 at the rodeo.

[smcgrath76]

From the most recent beef cow/calf weekly...

These Are Not Your Grandfather's Cows


Mature weight and milk production of many commercial beef cows are both greater than they were 30-40 years ago, says Glen Selk, Oklahoma State University Extension beef cow specialist. "Many ranchers haven’t recently weighed the adult cows in their herd to know what average mature weight to expect. Therefore, most commercial ranchers would underestimate the mature size of their cows. To expect large, heavy-milking cows to be in moderate body condition at calving and maintain condition through breeding, they must receive more feed than smaller, lighter-milking cows."

A larger, heavier-milking cow requires about 34% more energy on the average for an entire year, he says. Consequently, an operation that was carrying 100 of the smaller cows must carry only 66 of the larger cows in order to utilize the same quantity of forage from that farm or ranch. She also will need 34% more winter hay and supplement to maintain body condition.

"Because we have very high feed and fertilizer prices, this is a time to reconsider herd size to better fit the stocking rates required. Reduced stocking rates will be necessary on improved pastures if lower amounts of fertilizer are applied. The larger mature cow size also impacts the principle of percent body weight needed for heifers to reach puberty. Many ranchers underestimate the target weight for replacement heifers. If the cow eventually will be 1,000 lbs., the target for heifers is 650 lbs.; if she’s going to be the 1,250-lb. cow, then she needs to weigh 812 lbs. going into her first breeding season to expect a high cycling and pregnancy rate," Selk says.
-- Ron Hays, Radio Oklahoma Network

[farmers_son]

The fellow’s math in your quote is very misleading, even wrong. Yes the bigger heavier milking cow will need more energy and therefore more pasture but it is not a one to one ratio. The links you provided earlier show that the larger cows are more efficient and consume less dry matter per pound of cow weight than the smaller cow.

Please see:
AN EVALUATION OF THE RATIO OF CALF WEIGHT TO COW
WEIGHT AS AN INDICATOR OF COW EFFICIENCY http://jas.fass.org/cgi/reprint/46/3/614.pdf

Some producers may have small cows as a goal for their herd for reasons other than feed efficiency. While this goal might now be questioned not only because of the low relationship to efficiency but also because of the usual undesirable relationship to variable costs, it would appear that a selection index approach involving weaning weight and cow weight would be more effective than the ratio in achieving both goals of high efficiency and small cow size.
Undue attention to cow size could result in substantial loss of efficiency in the cow herd.

[farmers_son]

I did some more work on cow size. I went to Cowbytes and compared a 1400 pound cow to a 1000 pound cow. What made the most striking difference was not cow size but milking ability. A heavy milking cow could eat 25-30% more than a poor milking cow. It would seem that more milk equals more pounds of weaned calf but there might be questions about whether it is cheaper to put pounds on the calf some other way than through milk, for example early weaning. It does seem though that milk is the key more than cow size. You can have a herd of 1000 pound cows but if they are milking heavy they are going to have to eat. The 1000 pound cow producing a lot of milk could easily eat as much as a 1400 pound cow producing a moderate amount of milk.

[grassfarmer]

It depends what you read F_S, I've read plenty of research findings that show an 1100lb cow is the most efficient for the US northern plains so I would assume that to be similar to southern Alberta. There really is no right answer to this one as there are so many different circumstances. If you run cows on a headage basis on rented pasture where the landowner doesn't adjust for 1400lb cows versus 1100lb AUDs the big cow certainly has an advantage. Again it depends if you are a commercial breeder or a purebred one, if you are a commercial breeder that buys replacements you are in a different position to someone who breeds their own. On the commercial ranch buying in replacements the size of cow may be determined by weight/price of differing size replacement heifers relative to potential cull cow value. Another research finding I have encountered several times was that as cow mature weight increases fertility decreases.
Fertility is many times more important than feed efficiency on a ranch.

As a purebred/commercial breeder who runs all my cattle on a system where they really have to forage for their living my experiences have been thus:
1. Heavier and milkier cows are a disaster on my system - they cannot retain condition and rebreed although they may wean the best calves.

2. Some larger cows can prosper here - but in every instance it is because they are lower milkers and thus their calves are not much (if any) larger than the small cows calves.

3. Some small cows milk far too much and have the same problems as #1 cows

4. The cows that do best here are small or medium size cows that do not milk too heavy. There is no particular advantage to the medium size cow over the small in this category as they DO NOT consistently wean bigger calves.

5. Much of the data we read on cow efficiency is based on the assumption that a cow will eat x% of her body weight in forage per day. This is an assumption that bears no merit in the real world as it overlooks foraging ability - the cows desire/ability to go out and harvest their feed daily. I am convinced there are real differences between same weight/same breed cows in this trait. Of course if you haul harvested feed to them for 200 days this maybe has less relevance.

6. Longevity should be considered as to have it requires fertility. As an example we bought a group of simm/red angus heifers that have been great performers. From heifers to third calvers they all weaned a calf (a heavy calf) every year but with age they have fallen by the wayside, turning up open and I doubt if 25% will reach 8 year old.
By contrast I have one grading up line of purebreds that consistently wean calves in the bottom 25% on weight yet the cows are always fat. To test them out I ran the heifers off this line with mature cows instead of feeding them with my other heifers. They can handle this treatment and I'm convinced could winter on a straw only diet as mature cows. Now I think they are an efficient forage line - for my system, and my guess is they will last to 15 year olds. Of course to realise their full potential as feed savers I would need to feed them seperately or have a whole herd of them. Fed amongst less feed efficient cattle they carry more condition and don't wean a big enough calf.

But at the end of the day I realise the cows herd I have is the result of the selection pressure I put on them. If my ambition was to have a 1400lb cow herd, and managed/selected them accordingly some of my current "best" cows would look poor in comparison. It truly is a matter of horses for courses.

[DiamondSCattleCo]

In the midst of your little rodeos Kaiser, have you
remembered to keep the nuts in a couple of heavier
BW bulls for me? Some of you guys may like to see
those jackrabbits hitting the ground, but I'll take a
hunnert pounder any day

Rod

[smcgrath76]

Again, this relates heavily to what your resource base is and what you plan to do. An AUM is defined as a 100 pound cow (eating 2.5% of Bodyweight per day). The new technical definition raises BW to the 3/4 power, giving an advantage to the larger cow. A 1500 pound cow by this definition is not 1.5 AU, they are slightly less in fact. As well, as milk increases, intake increases just to support the gut mass for milking.
If you have a lot of aftermath grazing, ralatively flat land, decent moisture, etc. big cows probably make more money. If you graze year round, smaller cows are probably better.
High milk production can partially be overcome by calving later and weaning earlier, but it still may impact fertility given that there are only so many biological resources to go around.
At our place the math on 1200 pound cows, vs 1500 pound cows (based on metabolic body weight and similar milking ability) looks something like this...
100 1500 pound cows = 136 AU
136 AU = 118 1200 pound cows
If every cow weans 50% of her body weight this works out to...
750 * 100 = 75000 pounds saleable
600 * 118 = 70800 pounds saleable
It looks like the advantage goes to bigger cows, especially if you look at salvage value, until you consider that in our system these larger cows can't maintain condition, have a higher degree of opens and don't live as long. This is not right or wrong, just the fact of the matter is in our winter feeding system, these larger cows can't meet their metabolic needs, even though they are proportionally lower than a smaller cow per pound of cow. It is also easier for a 1200 pound cow to wean a 650 pound calf (54% of body weight) than a 1500 pound cow weaning an 810 pound calf. Reality is most producers weaning weights would be significantly less in a pounds weaned per cow exposed scenario.
Basically every producer needs to do their own math.
The high birth weight thing is OK for terminal cattle, but BWT is highly related to mature weight. We really work on finding curve benders to produce replacements as they grow fast and then quit at a reasonable size.

[per]

Not arguing with your math or reasoning but we must also consider that up until recently the 600lb calf brought as much per head as the 750lb calf. Going back to pounds per head to cows expose separates the pack even more. Many pounds per head weaned is important but few cows empty will result in more total pounds to sell. I guess I'm just repeating what has already been said. This thing still boils down to longevity and fertility. Only a cow that fits your environment will do that. Can't argue that those big old cows bring better salvage money but on our ranch the more moderate sized cows last longer.

[smcgrath76]

yep. It boils down to resources, marketing strategy, personal economics, etc. Larger cows given good resources may have a long lifespan. Sometimes limiting resources will reduce this.
Marketing into a carcass program or otherwise can change the economics again.

[rkaiser]

finally saw a heifer calve this year and had to help out a bit. She had a foot back so I laid down behind her and got things straightened out and gave it a pull. Funny thing about this heifer was that she is only 13 1/2 months old. Weighed her the day after she calved and she was 630 pounds. Her calf weighed 67 pounds and momma and baby are doing just fine.