The importance of feeding ewes correctly in mid and late pregnancy has been discussed recently by Tommy Boland, UCD School of Agriculture and Food Science, at the Teagasc lowland sheep conference and also at the ASA sheep masterclass.

Tommy’s presentations highlighted how ewes in good body condition entering late pregnancy feeding should be viewed as a valuable asset, with all steps taken to ensure that ewes do not lose body condition unnecessarily in late pregnancy.

There are a number of reasons behind this firm stance on maintaining condition. Ewe liveweight can be mobilised efficiently in early lactation to underpin a ewe’s energy intake and ensure peak milk yield is achieved.

Tommy showed how 100g of ewe liveweight can be utilised daily to make 3.8 MJ ME available, which is the equivalent of feeding 300g concentrates to ewes.

This represents a significant cost saving and while the ideal situation is a ewe at grass obtaining her full energy requirement from grazed grass, having a liveweight reserve that can be utilised if needed is extremely beneficial.

Furthermore, adequately meeting a ewe’s energy requirement in late pregnancy and preventing a loss in body condition will enhance lamb birth weight and growth rate to weaning.

Figure 1 shows the relationship between ewe body condition score and growth rate of twin lambs to 35 days of age, which clearly demonstrates the importance of ewes lambing in optimum body condition.

Four key areas

Tommy summarised four key areas farmers should take note of to achieve this goal.

  • Lambing date and litter size: The lambing date has a direct impact on determining a ewe’s nutritional requirement, as has the litter size. In the absence of raddling to determine lambing date, it can be assumed that the majority of ewes in the flock will go in lamb within 21 days of ram introduction. Pregnancy scanning is a vital component of management that should not be avoided, as operating a feeding programme in the absence of this information can result in twin lambs receiving the correct allocation, while the same level would be overfeeding single-bearing ewes and underfeeding triplet-bearing ewes.

  • Accurate assessment of liveweight: Tommy says that a huge contributor to inadequate nutrient intake in late pregnancy is under-estimation of ewe liveweight. “On many farms, a ewe’s liveweight is estimated at 65kg to 70kg when the actual liveweight is closer to 80kg. We ran our ewes in Lyons over the scales a few weeks ago and there were more ewes over 80kg than under at the start of late pregnancy feeding. If we underestimate for weight, then we are underfeeding for maintenance requirement, which will have a knock-on effect on how lambs (in the uterus) are being fed.” Feeding a ewe for 70kg liveweight when she is actually 80kg liveweight will result in that animal being underfed to the tune of 10%. Figure 2 shows the energy demand of ewes in late pregnancy and the deficit in intake if a ewe’s liveweight is underestimated by 20kg.

  • Silage quality: Tommy says that there is a disappointing uptake each year in forage testing. Similar to the case of ewe liveweight being underestimated, silage quality is usually incorrectly estimated, with farmers generally taking a higher value. Where silage quality is unknown and overestimated, then it becomes difficult to formulate the correct diet in late pregnancy. “Higher-quality forage reduces the level of concentrate supplementation required. There is a three-fold increase in the level of concentrates required when you reduce from 79DMD to 64DMD. Unlike cattle, sheep are very particular to silage quality and there are two main issues with low-DMD silage. Intake will be reduced with poor-quality silage and the energy supplied from a given intake will be lower, as less of the silage is broken down and utilised. Most sheep farms also use round bales of single-chop silage, which can reduce intake by up to 25%.” Where concentrates are being fed, the importance of using high-quality ingredients for energy and protein was also highlighted.
  • Management factors: How ewes are managed will also have a major impact on late pregnancy nutrition. For example, large ewes should be granted a feed space allocation of 500mm for concentrate feeding, with 250mm for restricted forage feeding and 150mm for forage offered ad libitum. The first two guidelines can be reduced by 50mm for small ewe breeds under 70kg. Trough management and keeping on top of any health ailments are also central to avoiding problems and, in particular, preventing metabolic diseases.

    • Swift action

    Frank Campion, programme adviser with the Teagasc BETTER farm sheep programme, says there are a higher percentage of ewes this year falling into the bracket of entering late pregnancy feeding in below optimum body condition. There is a big range between and within regions.

    Frank says that in parts of the north and northwest in particular, ewes went to the ram below target condition and some of these ewes have failed to recover. In contrast, on farms where ewes went to the ram in good condition, the majority of these have performed OK and are entering late pregnancy with an ideal condition score of 3.2 to 3.5.

    The focus now is turning to managing ewes in a manner which at least maintains body condition. “We would like to see no ewes lambing down at a condition score of less than 3.0 if we can avoid this at all. Where ewes are falling below target condition, the aim now is to ensure ewes don’t lose any more condition and maintain what they have. It can be as simple as pulling out some thinner twin-bearing ewes and joining them with triplets for additional feeding. The most important thing is that this is carried out in adequate time and preferential treatment is not delayed,” Frank said.

    Continual monitoring of body condition is also important to ensure that the late pregnancy feeding programme is satisfying requirements.

    “Any opportunity you can get to see how ewes are doing should be acted on. Scanning and pre-lambing vaccination are the obvious times where condition score can be monitored, but it is also important to check at least a percentage of ewes on a continual basis. This is physically handling ewes to get an accurate assessment, rather than looking in over the pen.”