Calf Size - What affects the size of calves at birth

[Broomcroft]

Hello

I have received conflicting thoughts on what affects the size of the calf at birth.

I have been told that the dam controls the size of the calf, or at least that is the dominant factor.

I know of at least one person who crosses a Hereford bull to a small Dexter cow without any problem I was told. The Dexter to Limousin bull Australian cross, produced a calf of 28kg, which is not that big.

I am getting calves that size and upwards from pedigree Dexters. My cows are all sorts and my bull is fairly big. He's a Redberry Prince lookalike but just slightly smaller.

When put to a smaller cow, I do get a smaller calf. And my biggest, wide-hipped cow has just produced quite a whopper, without any problem, from the same bull.

Does feeding affect the size of the calf much in your experience?

Clive

[wagra dexters]

28 kg is huge for a Dexter cow to be expected to deliver, even if, by better luck than management, she can. We have records of over 180 of our Dexter calves, their gestations and their birthweights. They go back 18 years to when we had bigger cows, and are weighed on reliable scales.
We have records of the sires and the dams in histogram form. The sires definitely influence the weights and the length of gestation, unlike the dams, who are all over the place, to several different sires, AI and natural service, the latter recorded only if witnessed, and shown not to have returned by bulling beacon. No weights have been guessed at, and only those actually weighed have been recorded.
Feeding up extra in the last month of gestation is not advisable.

[Duncan MacIntyre]

Feeding can influence the calf size but not only in the last month. The important stage for nutrition to be right to get good size of calf is during the phase where the placenta is establishing itself and determining the available blood supply to allow the foetus to grow. In late pregnancy the calf will draw on the cow for nutrition and will only be smaller than it should be if the nutrition is really very poor. Feeding in late laction does not have as much influence on oversize as you would think but if the cow is allowed to be too fat then there is more likely to be difficult birth.

Perhaps we should not be as afraid of crossing Dexters. I used to think it was a definite no no, but as the years have gone by I have seen quite a bit of crossing done. At present I know several breeders who regulary use a limousin bull on selected dexters with apparently little trouble. In 1996 at the Beef '96 exhibition in Perth we had two Dexter cows on stand with a Simmental cross calf and a Belgian Blue cross calf at foot, both calved unassisted and totally amazed all who came to see them. I do have reservations about Simmental and Charolais being used, but crossing can be done by experienced breeders who choose cows and sires carefully and manage the nutrition of the cows well.

Duncan

[Broomcroft]

Hi

Sorry, before we get down the wrong road, I don't feed anything extra at any time. I gave that impression in what I said. All my calvers are on almost ad lib hay. Never haylage or silage even. They are all fit and not fat.

I could feed them less but not by much. My hay tested as fairly average by the local feed merchant, maybe a bit high on sugar.

Other people are reporting that they too are getting around this as average, and commonly get over 30 kg, so I'm not alone.

Clive

[Woodmagic]

This ties in with the discussion elsewhere on the size of Dexter; sadly it is undoubtedly becoming bigger. Most of my calves run between 35lbs and 40lbs, the cows when mature at five years are around 40” at the withers. When I first kept them in the 1950’s anything over 44” would have been considered too big. The last show I attended, three years ago, I saw a bull that must have been close on 50”.
Discounting the traditional short leg (the true size may be quite different and can be inherited by the calf) it is obvious that if there are parents of this size, the calf is also going to be bigger. Personally I cannot even imagine a calf of 50lbs.
You could make some enquiries Duncan, I cannot recall the name, but a Scotch breeder who had for years crossed her cows, decided to breed pure, and told me that her cows were now living longer, hardly surprising when you think about it, you seldom get something for nothing in Nature.

[Broomcroft]

We haven't had to assist any births at all, apart from one backwards and that came out very easily!

My cows are from 12 different pedigree herds and all produce similar results, varying with the cow size fairly precisely. The sizes we are getting are the same as others are getting in their herds.

Clive

[Inger]

The ease of calving has a fair bit to do with the shape of the bull, particularly the head and shoulders and also his birthweight. Our Salty bull has the shape of head that means we have never had to pull any of his calves, no matter what cow he is put to. Most just fall out, even the big calves. The average weight of Salty's calves is 25kg.

Whereas our Australian bull who is a carrier, averages 26kg and because his calves are more chunky and less streamlined, some of his calves take more pushing.

[Broomcroft]

That appear to be our experience. We probably average 27-28kg and they just slip out easily. Our previous, short chunky bull with a big head, gave us far more problems.

Clive

[Inger]

Our birth weights range from 21.5 kg for a Grade 4 (purebred) heifer calf, which was the first calf of a 2.5 year old heifer, to 31.8 kg for a Grade 3 heifer calf from a six year old Grade 2 (75% Dexter) cow.

[Broomcroft]

Inger

That's pretty well the range we are getting too.

Clive

[Louisa Gidney]

I'm still interested in calf birth weights and only Inger has so far kindly provided me with any data. I'm looking for lists of actual birth weights, not mean and range. I want to run some different statistical tests, primarily Standard Deviation x 2.
The sample I started with was from a Roman site in Cheshire. This overlapped with Anglo-Saxon finds from Lindisfarne. This is thought to have been a vellum workshop, so only the metapodials, the lower leg bones left in the skin, are present. The monastery received tithes from estates between the Tweed and the Humber, so I would like a few data from many herds rather than a lot of data from a few herds. I would like to establish the normal range of variation among newborn Dexters to see how the pattern compares with the archaeological finds. It would be helpful to know the sex of the calkves, but not essential. All data gratefully accepted. I'll happily write this up for the Bulletin, but I need something to write about first!

[Jo Kemp]

I must apologise! Most of our calves are born in the field therefore weighing at birth is too much of a fag. I will look out a couple of calf weights I took last year - heifer mothers so likely to be on the smaller side.

With animals like charollais, it is often the hips not the head that make the calving difficult! Our neighbour was assisting almost every calving with one bull and the heads didn't 'stick' at all only the big bony bodies.

[Broomcroft]

Louise

How accurate do you want the figures. I pick mine up and judge the weight which will be within say 2 kilos either way. Is that too rough and ready?

[Louisa Gidney]

Jo, thanks. Doesn't matter if heifer mothers since no idea about the mothers of the archaeological calves, some are bound to have been heifers.
Broom croft, sorry 2 kilos is a bit too vague +/- half kilo/1lb acceptable

[Rob R]

I haven't got into the habit of always recording all birth weights, but the few results I can find read like this (in kg):

Heifers-
18
20

Bulls-
22
23
16 (born dead)
21

The results are a representative (if not very big) sample of calvings showing the kind of sex ratio we have experienced. We put a Dexter to a Limousin bull once (well, not so much 'put', the bull found his own way into the field). We didn't record the weight, but the calf was a big one & she had a difficult calving, resulting in a C-section & a calf that hardly grew