Birthweight

[Ky hills]

The topic of birthweights in another thread got me to reminiscing about some of our experiences with it years ago.
I had registered Charolais in the late 80's -mid 90's.
We weighed all the calves at birth on scales. The range was 60 lbs-135 lbs.
One 60 pound calf was an anomaly, a 1500+ lb cow that always had a smaller calf usually in the 85 range give or take 2-3 pounds. The other 60 lb calf was a twin to an 88 lb calf.
Outside of those nothing was ever under 75 lbs and very few of those except for an occasional small heifers calf or twins.
Most calves went in the 85+ to 120 range
Had a couple that weighed 135.
One year we AI bred sone heifers to an ABS heifer bull (Charolais) calves weighed 95-110, we pulled the 95# one.
Once in while we would have to pull a calf particularly when we started using a show ring bred 11 frame bull. Ever so often his calves would be what our vet called a dummy calf. Just big and slow to get started. The 135# calves were from him. My mature cows weighed from 1450-1800. They could have those 120# calves easy it seemed. The 135# were unassisted too.
At that time I saw some popular bulls with 150# BW. We were used to high BW but anything over 120# was something I did not like because I feared calving issues for our commercial customers. At the time it was kind of standard since EPD's had not made their way into the Charolais breed on any real scale, we considered under 100# a heifer bull.
If anyone mentioned that they were nervous about using bulls with those BW I always proceeded to try to discourage them from purchasing one of our bulls.
At that time a lot of work had been done to improve calving ease in the breed but it still wasn't where it is today. The local red and white spotted Simmentals at the time had much more of a reputation for hard calving than Charolais. The Limousin breed was just taking off like wildfire and had a bit better reputation for calving than Charolais.
Fast forward to today my cows are Angus and or Hereford, a little smaller and with those same breed make up bulls birthweights are from 50# to 75#. Years ago I did have a registered Angus Heifer to have a 100# bull calf unassisted but that was an exception sizewise.
Lots to consider on birthweights and calving ease. CEM ( calving ease maternal) is a factor that comes into play on the heifers side and makes it more necessary to use a lower birthweight bull in some instances, if the heifer has a higher BW. Some people recommend not retaining heifers from the higher birthweight bulls and just considering them as terminal calves.
I've steered clear of high birthweight females, as well as bulls. I tend to like breed average give or take a little either way.
I've used breed average Hereford bull on a few heifers and been ok.
I have come to believe that when using low BW and CE and probably even breed average for those traits bulls of the same breed as the heifers that the calves should come relatively easy.
I believe the crossbreeding, hybrid vigor effect can significantly affect calving.
I've not noticed a huge difference in calf size from most of the Angus and Herefords I have used.
However we have had some big calves born from commercial black heifers presumably Simmental or Limousin or crosses with those from low birthweight high CE Angus bulls. That's why I'm hesitant to use continental bulls even if CE on British breed heifers.

 

[GoWyo]

The topic of birthweights in another thread got me to reminiscing about some of our experiences with it years ago.
I had registered Charolais in the late 80's -mid 90's.
We weighed all the calves at birth on scales. The range was 60 lbs-135 lbs.
One 60 pound calf was an anomaly, a 1500+ lb cow that always had a smaller calf usually in the 85 range give or take 2-3 pounds. The other 60 lb calf was a twin to an 88 lb calf.
Outside of those nothing was ever under 75 lbs and very few of those except for an occasional small heifers calf or twins.
Most calves went in the 85+ to 120 range
Had a couple that weighed 135.
One year we AI bred sone heifers to an ABS heifer bull (Charolais) calves weighed 95-110, we pulled the 95# one.
Once in while we would have to pull a calf particularly when we started using a show ring bred 11 frame bull. Ever so often his calves would be what our vet called a dummy calf. Just big and slow to get started. The 135# calves were from him. My mature cows weighed from 1450-1800. They could have those 120# calves easy it seemed. The 135# were unassisted too.
At that time I saw some popular bulls with 150# BW. We were used to high BW but anything over 120# was something I did not like because I feared calving issues for our commercial customers. At the time it was kind of standard since EPD's had not made their way into the Charolais breed on any real scale, we considered under 100# a heifer bull.
If anyone mentioned that they were nervous about using bulls with those BW I always proceeded to try to discourage them from purchasing one of our bulls.
At that time a lot of work had been done to improve calving ease in the breed but it still wasn't where it is today. The local red and white spotted Simmentals at the time had much more of a reputation for hard calving than Charolais. The Limousin breed was just taking off like wildfire and had a bit better reputation for calving than Charolais.
Fast forward to today my cows are Angus and or Hereford, a little smaller and with those same breed make up bulls birthweights are from 50# to 75#. Years ago I did have a registered Angus Heifer to have a 100# bull calf unassisted but that was an exception sizewise.
Lots to consider on birthweights and calving ease. CEM ( calving ease maternal) is a factor that comes into play on the heifers side and makes it more necessary to use a lower birthweight bull in some instances, if the heifer has a higher BW. Some people recommend not retaining heifers from the higher birthweight bulls and just considering them as terminal calves.
I've steered clear of high birthweight females, as well as bulls. I tend to like breed average give or take a little either way.
I've used breed average Hereford bull on a few heifers and been ok.
I have come to believe that when using low BW and CE and probably even breed average for those traits bulls of the same breed as the heifers that the calves should come relatively easy.
I believe the crossbreeding, hybrid vigor effect can significantly affect calving.
I've not noticed a huge difference in calf size from most of the Angus and Herefords I have used.
However we have had some big calves born from commercial black heifers presumably Simmental or Limousin or crosses with those from low birthweight high CE Angus bulls. That's why I'm hesitant to use continental bulls even if CE on British breed heifers.

Bouncing around in the back of my mind is the idea I heard somewhere along the line that a heifer or cow ought to be able to have a calf that weighs 7% of her body weight in good condition (BCS 5-6). So, a 1,000 lb. heifer should have a 70 lb. calf and a 1500 lb. cow should have a 105 lb. calf. Any thoughts on this?

 

[Ky hills]

Bouncing around in the back of my mind is the idea I heard somewhere along the line that a heifer or cow ought to be able to have a calf that weighs 7% of her body weight in good condition (BCS 5-6). So, a 1,000 lb. heifer should have a 70 lb. calf and a 1500 lb. cow should have a 105 lb. calf. Any thoughts on this?

That sounds very reasonable.
Lots factors go into birthweight, that can affect it, nutrition of the dam, time of year, etc. I believe shape of the calf has a lot more to do with calving ease than actual birthweights, but definitely the weight/size can a contributing factor for calving difficulty.

 

[lithuanian farmer]

Bouncing around in the back of my mind is the idea I heard somewhere along the line that a heifer or cow ought to be able to have a calf that weighs 7% of her body weight in good condition (BCS 5-6). So, a 1,000 lb. heifer should have a 70 lb. calf and a 1500 lb. cow should have a 105 lb. calf. Any thoughts on this?

I have heard something about 10%. But it mostly depends from the shape of the calf than it's weight.

 

[GoWyo]

Or maybe the 7% idea is an average. I have used a couple bulls for heifer clean up that resulted in calves that were more like 8% of the heifer's body weight, but those calves were long and snakey and I never had to assist any of them.

 

[redcowsrule33]

Was reading some random articles from Meat and Livestock Australia and found this interesting tidbit:

Dystocia is an abnormal or difficult birth or labour, and results from a foetal-pelvic disproportion. Several factors can cause dystocia, including:

• large calf size – a function of genetics of both maternal and paternal traits, as well as varying rates of maternal nutrition from conception through to birth.
• placental size – potentially important; a function of nutrition at conception through to about day 80 of gestation. A positive correlation between placental size and birthweight of the calf is well documented, and excessive nutrition immediately post-joining can influence calf size.

Never thought about the first three months having an influence on weight. Everyone looks at the end of gestation.

 

[highlandvines]

Interesting. I've noticed our Summer calves always seem smaller. It seemed odd as they have pretty good grass to eat vs hay for the winter/early spring calving cows. I assumed it would be heat or something but maybe it has something to do with the first 80 days.