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Sunday 11 December 2016

Selecting for both low birth weight and growth is tricky but worth it

Denis Minogue

Published 12/12/2012 | 06:00

The autumn born calves are now weaned about two months. They were housed approximately one month ago.

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Once housed, we began our winter feeding regime for the progeny. The first cut silage has an estimated drymatter digestibility (DMD) of 70pc, which is good for 2012 but still 8pc lower than last year.

At present, males are being offered 2kg of concentrate per head per day, plus ad lib first-cut silage. Females are being offered 1kg of concentrate, plus ad lib first-cut silage.

This feeding regime is essential for the Derrypatrick system, which aims to maximise compensatory growth following turn out to pasture next spring.

Our next focus is to prepare for calving in 2013. Our first aim is to have cows in adequate condition prior to calving.

This will require close monitoring of body condition score to avoid any extreme condition loss during the winter.

Currently, the digestibility of the silage being offered to the mature cows stands at 60pc DMD.

Silage of this quality, fed ad lib for the duration of the winter will result in extreme loss of condition. For this reason, concentrate will be offered, for the moment, at a rate of 0.5kg/ head/day.

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If body condition decreases too much, it will have a notable impact on cow fertility during the following breeding season.

Ultimately, this will lead to low in-calf rates and higher replacement rates, which are all additional costs to the farm.

Prior to calving, cows will be moved out to individual pens. Here they will be offered additional supplement (most likely first-cut silage fed ad lib) until calving occurs.

Increasing the energy intake of the cow at this stage in the gestation, two to three days prior to calving, will not have any adverse effect on calving.

It will, however, increase her energy reserves to calve down effectively and provide an adequate supply of colostrum for the calf immediately post calving. It is evident from the Derrypatrick herd that milk will be a key driver of increased output on suckler farms.

Milky

Let's just remind ourselves of the many benefits of a milky cow. The physiology of the bovine placenta prevents transfer of maternal serum immunoglobulins to the calf before it is born. So the calf is entirely dependent on the immunoglobulins that it gets from colostrum for protection from disease.

In addition to disease protection, colostrum also provides the neo-natal calf with high-quality nutrition and many growth factors and hormones that can be beneficial for initiating function and growth of the digestive tract.

The cost of poor milk supply in the cow is not documented and often overlooked. For example:

nThe extra labour associated with getting additional colostrum into a calf;

nVeterinary costs such as callouts and medicine.

In addition to these direct costs, there is also calf survivability. If the immune system is compromised from the beginning, the survivability of that animal is undoubtedly affected.

Although difficult to quantify on farm at a national level, these additional costs place further pressure on Irish suckler systems. Calving is obviously a crucial time of year for every suckler farmer. We try to eliminate or reduce calving difficulty as much as possible for this period.

Our ability to achieve this is improved by sire selection using high reliability bulls from the beef index that rank 4-5 stars for calving difficulty across breeds.

But there is a question as to whether we could move the industry one step further down this road?

Beef production in this country will be further enhanced by selecting for low birth-weight sires, while at the same time selecting for growth.

Granted, there is a negative relationship between these two parameters, but it can be achieved.

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This will reduce the incidence of calving difficulty while delivering positive growth performance at each stage of the life cycle.

However, this would require farmers to begin recording birth-weights on a national scale to sufficiently build up a database to enhance our selection ability for these two traits.

Selecting for low birth-weight, while still achieving growth, has the potential to drive the industry to a stage where calving becomes more of a routine exercise, with minimal labour input, without reducing our carcass output.

This is what suckling has to move towards – a reduction in the cost of producing beef. The potential is there, so wouldn't it be worth the extra effort?

Denis Minogue manages the Derrypatrick research herd at Teagasc Grange. Email: denis.minogue@teagasc.ie

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