Can Angus Birthweight genetics be too low & get dead calves?

[Ozhorse]

Can reducing feed quantity in the last 3 months lead to calves which are so small that they don't survive birth and the cold (like 0 Celcius which is common here plus strong winds)?

Does having Angus cows joined to really low birthweight Angus bulls mean I could have gone way too far on the low birthweight genetics?

Could it be a combination?

I am asking because it may mean different bull selection for me - I am trying to work out if I should stay away from really low birthweight bulls - like this one I used for AI on 10 registered cows.

http://abri.une.edu.au/online/cgi-bin/i ... 9=5D5F5B27
BOOROOMOOKA ON TIME D105(AI)

Usually in the last 7 years I have been raising cattle, these same cows would produce maybe two less calves than the number of cows I have, (between 90 - 120 head). This included during droughts and I have always been very impressed with their performance. They will have one every 10-11 months if you let them.

Calving started on the 14th July. There are 42 out of 120 expected calves arrived of which 4 that I know of so far (and probably more) are dead. Other calves are very very small, and may not survive the cold here.

They have had a hard 12 months. Last winter was hard and snowy. Then the farm was burnt out by bushfire 2500 of 2700 acres. But the cows were sent away on agistment straight after the fire and were on good country (but might have had a fair bit of liver fluke over the summer). Three months ago they came home to pastures flogged out by fire and sheep. They were fluke drenched and I think that helped. Older cows were put on longer pasture so should be OK, but one of them has lost a calf. The other dead/small calves are out of heifers with low BWT sires and dams by low BWT bulls on short pastures for last three months.

My 10 registered AI'd cows (they are 8yo and have had calves every year) usually have big solid calves. This year they were AI'd to the bull above who has very low BWT figures. While they had reduced diet in the last three months they are in fairly good condition, not poor. Their calves are tiny tiny. Out of 5 born, one is not there any more and the cow is leaking milk all over the place and not acting like she has a calf. Also the calves were born about a week earlier than expected. They were AI'd on the 29th October and 4 arrived by the 1st August when it should have been the 7th August (one arrived on the 7th). I have not checked them in the last 24 hours so maybe we only got 5 by AI. I know some were served by a backup bull a few weeks later.

I have some younger cows who did it way too tough last winter, managed to get back in calf but are still thin, were joined to a low BWT bull and still doing it tough - they have had a few super tiny calves one of which is dead - this I can understand may be a combination of environment and genetics - but the big old registered cows - that makes me think there might be a big genetic component to the dead small calves.

I did not want to use a bull with genetics for such a low BWT but I hitch-hike on a neighbours AI program and I am restricted in bull semen choice and I chose him for temperament, positive fat scores, milk, scrotal size (looking for fertility in tough conditions) - and figured low BWT probably was not bad, even though I would like to get the BWT genetics of the herd more toward the average, than the low, where it is now. I wanted to get the BWT more to the average so the weaned calves were likely to be a better size at the weaner sales.

I did not think that low BWT meant so low that the calf was too small to survive. I also thought that short gestation was a reasonable way to achieve a low BWT. But perhaps it is not good to have them born a week or more early as they are still too weak and small?

I have 38 x 10 year old cows calving to a big bull with a BWT of 5.1. These calves are strapping and doing well.

Bull Clea NRZ B045
http://abri.une.edu.au/online/cgi-bin/i ... 9=5E5D5927

Usually my registered cows have calves bigger than my old herd cows, but not this year.

Anyone here have experience with getting birthweight genetics too low under tough conditions?

 

[Ozhorse]

I think I have finally worked out how to post pictures here. It has taken me about 3 hours.

My photos are not quite like most of the pretty cow photos here. These are my older cows and their calves last winter, 2012.

 

[Lucky_P]

Oz,
Low BW genetics is unlikely to be the problem - but poor nutrition - which you've already zeroed in on - is...
There is variability among sires with regard to calf vigor - some of the most vigorous calves we've ever had hit the ground were out of exceedlingly high CED/low BW sires.
I'm unfamiliar with most of the Australian cattle in that bull's pedigree, but most of the American genetics in his background are fairly middle of the road 'calving ease' stuff.
That said, a tiny calf in severe winter weather conditions will chill more rapidly than a larger calf, just due to less body mass per unit of surface area.

Poor nutritional levels, particularly during the third trimester, can be very influential on calf vigor and survival. Dietary protein levels are especially important during this timeframe.
Researchers at US MARC, back in the '90s did some studies with beef heifers - one group was fed a ration supplying 100% of NRC recommended protein levels, second group received 50% of NRC protein recommendation. Calves born to the protein-deficient group were less adept at generating body heat, were slower to get up and nurse, achieved lower serum immunoglobulin levels (probably due to both poorer absorption of colostral antibodies AND poorer colostrum quality from their protein-deficient dams). Overall survival rates were significantly lower in calves from the protein-deficient heifers, and, I suspect, terminal performance was probably impacted as well.

 

[Ozhorse]

Thanks Lucky for that advice and the information on protein levels and quantity of protein.
I will see what the result is by the end of calving. If there is a correlation between which paddock the cows have been run in in the last three months before calving and how burnt out it was (and how many sheep they were sharing it with) and calf size/mortality then that should explain it.

I did think the quality of the burnt area of the pasture was better than in unburnt areas because of the new growth and fertilizing effect of the ash, (the sheep did especially well this autumn on the burnt pastures) but I dont suppose you can beat quantity of feed for cattle.

I will have to look on the bright side, and just blame the fire. I only lost one calf to the fire and I could easily have lost most of the herd.

 

[ousoonerfan22]

With the drought we had the last two years some of our cows calved a couple of weeks early and some had small calves. The pastures and the hay meadows were in terrible condition so this along with many days over a 100 degrees.... the cows looked really poor and so did some of the calves. We have one cow that has always looked like a cull cow but before the drought she would give birth to the largest calf and raise the best calf of the herd but this year she had a runt.