Farm Ireland
Independent.ie

Wednesday 20 September 2017

Take good care of ewes in the weeks after mating

Tommy Boland

Tommy Boland

Yesterday saw 375 ewes and ewe lambs bred using laproscopic AI at Lyons. Sponges were pulled in two batches on Saturday morning with a three-hour time difference.

Ewes and ewe lambs received 500 units of Pregnant Mare Serum Gonadotrophin (PMSG) to increase ovulation rate, at sponge removal. As not all ewe lambs are being AI'ed, rams went in with the remainder 36 hours after sponge withdrawal. Rams will be turned out to pick up repeats 14 days after the initial mating.

We are targeting a scanned litter size of 1.9-2.0 with the mature ewe flock, even though we have fallen about 0.15 lambs short of this for the last year or two, partly due to an increase in the number of barren ewes.

The mature ewes had an average weight of 74kg at mating and the ewe lambs averaged 50kg. This puts the ewe lambs at approximately 68pc of their mature live weight. It's important to have ewe lambs at a minimum of 60pc of their mature weight at mating.

Recent research from Britain shows that if you feed lambs for catch-up growth after mating you risk these ewe lambs producing lambs of low birth weight, with reduced vigour, reduced reserves of brown fat (the main energy reserve in the newborn lamb) and consequently increased risk of mortality.

The ewes and ewe lambs will remain on a stable plane of nutrition during the first month after mating. After mating, it takes approximately three weeks for the embryo to implant.

Loss

During this time the embryo is extremely susceptible to loss, especially if there is stress on the ewe. Therefore, handling of the flock should be minimised during this period. Also, overfeeding during this period is to be avoided, as this too can increase the risk of embryo loss through increased clearance of progesterone (the hormone responsible for the establishment of pregnancy) from the system.

Also Read


Some 88 lambs were sold two weeks ago and with a price of €4.50/kg they yielded a carcass value of €92 per head. On October 21 last year, we received €108.68 for lambs.

Grass growth rate is remaining reasonably strong with 31kgDM/ha/day grown in the first week of October. This is slightly ahead of normal for Lyons and only marginally down on the growth rate of 33kgDM/ha/day from the previous week. Meals have been introduced to all lambs and they are now up to 350g/hd/day.

We have received the silage test results and they are looking reasonably good. DM is 33pc, pH 4, protein 13.5pc, DMD 73pc and ME 11.2 MJ. Silage was harvested on May 27 and coincided with the dry spell of weather at this time, which obviously had a big impact.

The farm manger is targeting an earlier harvest date in future, but the poor grass growth in spring this year did not allow for this. Also this year the grass was tedded for wilting and this had a major impact on drying and wilting the grass in a swath, which is difficult at the best of times. There is a significant quantity of very poor silage as a result of the inclement summer.

The results of the Teagasc silage survey indicated that one in four samples tested had a DMD of less than 60pc and about one in 12 samples had a DMD of less than 55pc. This will greatly restrict the nutrient supply (energy and protein) from these silages for pregnant ewes.

The problem will be further exacerbated where there is also poor fermentation. This will result in increased concentrate supplementation in late pregnancy. What we must avoid is over-estimating the contribution made by these silages to nutrient supply. My advice is to test your silage now and use these results to construct your feeding programme. Underfeeding the ewe in late pregnancy must be avoided as it will compromise the lambs for the rest of the year.

Dr Tommy Boland is a lecturer in sheep production and ruminant nutrition at UCD's Lyons Research Farm, Newcastle, Co Dublin

Indo Farming