The sun shines and lamb growth rates improve as Spring settles in

Ewes and lambs are moving out of pasture for Tom Boland.
Ewes and lambs are moving out of pasture for Tom Boland.

Tom Boland

The recent improvement in weather conditions and grass growth is very welcome, and is certainly being well received by our lambs at Lyons. The twin suckling lambs grew at 315g per day from birth until four weeks of age.

Since turn out, these ewes are receiving grass only and are currently grazing the hill ground at Lyons. The artificially reared lambs are almost ready to be weaned. Their concentrate intake is increasing nicely and we will wean them when they are consuming approximately 250g per head per day.

Between birth and four weeks of age, these artificially reared lambs had an average growth rate of 340g per head per day. This is an impressive growth rate considering these are all triplet or quad-born lambs. Once again, it indicates the growth potential which exists in the new-born lamb. Unfortunately, in many instances, this potential is not realised due to inadequate milk production of the ewe.

This can be as a result of genetics, nutrition or disease. Enhanced record keeping and selection is required to ensure that only the ewes with good potential to milk are retained within the flock and used to provide replacements.

Lactation

Frank Campion's work this year is examining the intake potential of the ewe in early lactation, her milk production during the first six weeks of lactation and how she responds to concentrate supplementation.

This is one of the most intensive trials with the sheep flock in my time at Lyons, and Frank and his team are working long hours to ensure the data is collected accurately.

It is too early to draw any conclusions from this work, but the early findings show that concentrate supplementation will push the rumen pH of the ewe down towards and even below six after feeding. One would like to see this closer to 6.5 to 6.8 in a suckling ewe. It is unclear yet if this lowered rumen pH has a detrimental effect on ewe or lamb performance.

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There is a substitution rate of 50pc when concentrates are offered in early lactation. This means that feeding 500g of concentrate dry matter (DM) leads to a drop in grass intake of 250g of DM. Milk yield of these ewes was 2.5 litres per day in the second week of lactation.

As the ewes are housed on slats and offered zero-grazed grass, we measure grass intake on a daily basis. The wet weather during March certainly presented some difficulties for grass intake.

There appears to be a strong relationship between grass DM content and grass intake (ewes eat more grass when it is dryer). The lambs on this study are offered creep access to zero-grazed grass to ensure their digestive systems are developing appropriately prior to being turned out to grass in one week. Growth rates of these lambs are in line with the animals outdoors.

Fiona McGovern, one of our Phd students, collected faecal samples from her lambs at four weeks of age on April 9 as she continues to track the immune function in these animals.

As we would expect, there was no sign of a nematodirus challenge in these young lambs. There was evidence of coccidiosis in about 15pc of the samples tested. However, there were no clinical signs of coccidiosis in these lambs.

Monitoring

We are actively monitoring this. The remainder of the commercial ewes are currently grazing the hill. Ewes and lambs are moving out of pastures when they achieve a post grazing sward height of 4.5cm.

We then use dry ewes and some heifers to take this down to approximately 3.75cm.

This height will increase to approximately 5cm as the grazing season progresses, but in the spring it is crucial to achieve a low post-grazing sward height to maintain sward quality in later rotations.

  • Tommy Boland; Lecturer in sheep production, Lyons Research Farm, UCD. tommy.boland@ucd.ie

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