gestation length

what affects gestation length other than fall calving?

how many generations have been shown to be necessary to affect this, say when importing a breed from europe to the US?

Some bulls will throw calves with a shorter gestation length.  A lot of the heifer bulls out there are generally shorter gestation bulls so their calves are generally smaller.

I am  not sure if gestation length is affected equally by both parents or not, however, I am certain that a sire can affect gestation length in his calf crop. I have seen this in our herd bulls over the years. This became most apparent to me when we started having calves from two of our Irish imported bulls in the 70s. Highfield Irish Mist was consistently 8 to 10 days shorter gestation than IDS Duke of Dublin was. We never had any real calving issues with either bull, however, the Duke calves were consistently higher BW calves. While saying this, I am also very aware that many of the BW issues that appear from time to time, are closely related to the birth weights in the background of the dam.

Right now, I am using a full Irish son of Highfiield Irish Mist in our herd, and his calves have the shortest gestation length I have ever had, from any Shorthorn herdsire used here. He is a great bull to use on heifers as his calves are born easily and are vigorous at birth.It seems to me that there are both genetic and environmental issues that can affect gestation length.

I'd say sex affects gestation length.  Been our experience that heifers are usually born earlier and bulls later.

knabe said:

what affects gestation length other than fall calving?

how many generations have been shown to be necessary to affect this, say when importing a breed from europe to the US?

Click to expand...

I don't really know the answer to your question, but I wonder, from observation of mine and others', if size, sire/dam/calf, might play a part.  Compared to regular sized cattle I've either owned or worked with, my Lowlines consistently calve a week to 10 days earlier than the gestation tables indicate.

knabe said:

what affects gestation length other than fall calving?

how many generations have been shown to be necessary to affect this, say when importing a breed from europe to the US?

Click to expand...

How does fall calving affect gestation?

worthabit said:

knabe said:

what affects gestation length other than fall calving?

how many generations have been shown to be necessary to affect this, say when importing a breed from europe to the US?

Click to expand...

How does fall calving affect gestation?

Click to expand...

some out here claim a 5 lb reduction due to poor feed versus spring when feed is at it's peak.

By the rules of linear measuring, bulls with wider shoulders will sire calves with shorter gestation length. Wide shoulders (vs. narrow) is a sign of masculinity in a bull and masculinity reduces gestation among other things. Also, gestation can vary by breed.

I have found that gestation can vary as much within breed as between breeds.