Dates

helen salmon · Post by **helen salmon** » Wed Apr 08, 2009 9:48 am

With a known date of mating (in this case by AI), how accurate is the predicted date for calving? I know with dogs it is quite usual to be 5 days over the predicted date. Is this the same with cows?
Helen

Broomcroft · Post by **Broomcroft** » Wed Apr 08, 2009 10:14 am

Helen - We use 280 days minimum - 290 maximum to predict births, somewhere between being the average I suppose. I think it's fairly accurate. We do have some dams who always seem to calve first and produce smaller calves, so I assume their gestation period is shorter than most, so there must be some variation.

Edited By Broomcroft on 1239182418

wagra dexters · Post by **wagra dexters** » Wed Apr 08, 2009 12:52 pm

Helen, 283 is the accepted average gestation for cattle generally. The following records are all Dexters, and only for alive & well calves for whom we have the exact date of service.

Our shortest was 262 day gestation. The longest was 289 days.

We have had 120 calves born from day 274 to 283, 23 calves born before day 274, and 23 calves born after day 283.

We've had 16 calves born on day 280, and 15 born on day 275, the histogram forms a sideways W shape with these days as the two spikes.

Bulls seem to have a greater influence over gestation length than cows, the gestation length of sires calves falling into tighter time frames than the gestation lengths of the dams calves, if you can understand what I mean.

Margaret.

helen salmon · Post by **helen salmon** » Fri Apr 10, 2009 10:07 am

Many thanks for your replies.
I am reassured that Belle is within the realms of normal. She is on day 284 today and waiting. I hope it won't be too much longer for the sake of my nerves!
Helen

Inger · Post by **Inger** » Fri Apr 10, 2009 10:31 am

I allow them 2 weeks before their due date, to 2 weeks after their due date. Anything outside that and the due date is incorrect. It must have been either a previous cycle or a later cycle to the cycle observed.

One of our bulls consistantly threw calves that were born 10 days to 2 weeks earlier than their estimated delivery date. Whereas one of our current bulls throws calves that arrive fairly much on the due date.

wagra dexters · Post by **wagra dexters** » Sat Apr 11, 2009 1:05 am

We don't do previous or unobserved by AI.
We have had several perfectly healthy normal calves who were a full 3 weeks early, if 283 days is taken as standard.
I do the AI personally, and the records, and all of those early calves were DNA parent verified.
Three weeks early does not necessarily always mean the dates are incorrect as Inger claims.
We had one bull calf by Saltaire Guiness who was born exactly 9 calendar months after the cow's previous calf. That bull calf went on to become the heifer bull for a commercial hereford breeder

Margaret.

Inger · Post by **Inger** » Sat Apr 11, 2009 10:56 am

That's unusually early though Margaret. I've never had a calf arrive earlier than 14 weeks early. The calves were out of a Salty bull as well co-incidently. Must be something in the genes.

wagra dexters · Post by **wagra dexters** » Sat Apr 11, 2009 2:55 pm

We may have some confusion about sires here Inger.
The bull we call Salty is Hiyu Salty Rambler 4th. His sire is Saltaire Platinum, not Saltaire Guiness.
Apart from the extremely early dwarf Saltaire Guiness calf, the sires of most of our earlier calves are Woodmagic Hedgehog 3rd, and his sons Wagra Wedgwood & Wagra Zeppelin, all chondro non-carrier calves.
It seems as though the smaller calves may be gestated for shorter periods.
Margaret.

Inger · Post by **Inger** » Sun Apr 12, 2009 4:29 am

Our Salty is a son of your bull then. His father was Hiyu Salty Rambler 4th. Salty Pioneer is a non-carrier as well. His calves averaged 26 kgs at birth, whereas another bull we are using is a smaller non-carrier bull, who produces much smaller calves, which are usually born only a day or two off their due date.

I firmly believe that gestational length has more to do with genetics than the size of the calf.

Edited By Inger on 1239507061

wagra dexters · Post by **wagra dexters** » Mon Apr 13, 2009 1:37 pm

The size of our calves obviously has a lot to do with the genetic structure of our herd .
Our average calving weight used to be 21 kg but for the last eight years the heaviest of our calves have been 21 kg.
I think that 26 kg is very heavy for a Dexter calf, but then I don't know what other breeders expect their calves to weigh.
Margaret