Farm Ireland
Independent.ie

Tuesday 17 October 2017

Two-thirds of cows calved in just 32 days in Derrypatrick Herd at Grange

Denis Minogue

Recent mild weather, a welcome change for all parts, facilitated a considerable improvement in ground conditions throughout the country. Although Derrypatrick was no exception soil temperatures still remain low, averaging 3.2°C 5cm down over the past 10 days.

For this reason, we have delayed the first application of nitrogen across the farm. Despite this, we have turned out livestock to pasture in order to set up the grazing platform for the year by grazing out any grass that was carried over the winter. At present, we have turned out all the yearling progeny (heifers, bulls, and steers), and approximately 30 cows and calves. Cold conditions at night hindered our ability to turn out some of the younger calves, but these will be turned out too once they are strong enough and have bonded sufficiently.

The calving season is also fully underway. We have 63pc of the herd calved down within the first 32 days of the calving season. By compacting the calving pattern earlier in the season, we hope to increase the number of cows returning to normal cycling before the onset of the breeding season. This is essential for a seasonally-calving suckler system trying to capitalise on grazed grass.

In addition, earlier born calves are heavier at weaning and slaughter, increasing output from the farm. The challenge is to balance calving date with the start of the grass grazing season, as space for housing cows and calves post-calving can be limited and the cost of indoor feeding is greater than grazed grass.

So the aim is to match calving date with expected turnout date as much as possible. This alleviates housing pressures and reduces feed costs but it can only happen if soil conditions and grass growth are adequate.

The turnout date at Derrypatrick might seem early, especially given it is located in the northern half of the country.

But the objective must be early turnout regardless of location to maximise the amount of grass that makes up the annual feed budget. Obviously, grass supply and ground conditions have to be taken into account, but increasing grazed grass is a sure way to reduce production costs.

At present, pre-calved cows are being offered 60DMD silage ad-lib plus 0.5kg of concentrate per head per day. When mentioning this diet to visitors, we are questioned about pre-calving dietary options, such as the inclusion of straw to reduce birth weights and incidences of calving difficulty. However, the correct dietary formulation is dependent on body condition post housing. In other words, energy intake can be restricted for cows in good condition or if the quality of winter feed is very high.

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For example, in 2012, when we had 73DMD silage, the cow's diet was very different to this year. Cows were restricted to approximately 6-7kg DM per head. Similarly, given the poor quality of silage in 2013, the inclusion of straw in the diet would lead to body condition loss, which could lead to a prolonged anoestrus period. Additionally, restricting the energy intake of cows in late pregnancy to such a degree is likely to reduce the passive immunity status of the calves by reducing the immunoglobulin concentration of dams' colostrum.

So far, our birth-weight average of 50kg across all breeds appears to be similar to 2012. This would suggest to us that sire selection is the main determinant of birth-weight, rather than the feeding regime. However, this comes with the caveat that nutritional intake, particularly energy and minerals/vitamins, is adequate in both scenarios being compared.

This is supported by a research experiment carried out at Grange by Dr Mark McGee. He examined the effect of nutritional restriction in late pregnancy on calf birth-weight and calving difficulty.

In this study, the addition of straw to moderate digestibility grass silage did not significantly reduce calf birth-weight or calving difficulty, when compared to a silage-only diet. This would suggest that when the suckler cow is put on a restrictive diet, she mobilises fat reserves to continue delivering adequate nutrients to the foetus.

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

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