Managing the Ewe in Late Pregnancy

Brian Hughes, Drystock Advisor, Teagasc Claremorris

As lamb weight increases by 70% during the last 6 weeks of pregnancy the management of the ewe flock in this period is critical for a successful lambing season.  Scanning is a must for serious sheep farmers and should be used to increase productivity and profitability. The optimum time to scan ewes is between 80 and 90 days post ram turnout.

In a year of spiralling costs, empty ewes can be sold as they become fit and will generally acquire a good price at this time of year.  If you have a lot of empty ewes, you should try and find out why this is the case?  This can be a ram fertility issue but could also be an underlying abortion issue which would need further investigation.  Ask yourself were the ewes in adequate body condition at mating time?  Seek veterinary advice if necessary, to avoid this issue happening on the farm again.

This year alot of out-wintered ewes are in very good body condition because of the mild winter and the availability of plenty of grass on many farms.  This should influence the feeding regime pre-lambing.  Producing lambs of optimum birth weight and ensuring ewes have adequate quantity and quality of colostrum for their new-born lambs is essential.  This is achieved by using scanning results and grouping ewes by predicted litter size and offering the appropriate late pregnancy nutrition based on the number of lambs being carried by ewes in each group.

Optimum lamb birth weight

The optimum birth weight per lamb varies by litter size. It can be defined as the weight at which lambs have the best chance of survival balanced with the weight that most lambs can be born naturally with minimal assistance.

The target optimum birth weights for lowland flocks is 6kg, 5kg and 4kg for lambs born singles, twins and triplets, respectively (based on 75kg mature weight lowland ewe).  Ewes carrying singles with a good grass supply and good body condition may have larger lambs and thus, lambing difficulty.  Once lamb birth weight increases above the optimum birth weight, so does lamb mortality.  This is mainly due to lambing difficulty associated with over-sized lambs.  As lamb weight decreases below optimum birth weight, lamb mortality increases.

Feeding the ewe in late pregnancy

So pen ewes according to their scanning results (singles, twins, triplets) and lambing date which can be calculated if rams were raddled. This will lead to more targeted meal feeding.  Also, ewe body condition should be accessed.  Thin ewes will require extra feeding.  

Good quality, high DMD silage is essential for pregnant ewes.  Concentrate feeding should be based on this information and litter size.  A high quality crude protein source such as soya bean meal is important for pregnant ewes.  Commence concentrate supplementation in time, especially for ewes carrying triplets (8 to 10 weeks post expected lambing date).

As a rule of thumb feed single bearing ewes require 30% less than twin bearing ewes building up to a maximum of 0.5kg in the week before lambing. Triplet bearing ewes should be fed 30% more than those carrying twins up to a maximum of 1kg prior to lambing. When silage quality is extremely poor, such as with a DMD in the low 60s or worse, higher level of concentrates will be needed.

Ensure ewes have sufficient feed and floor space.  Also ensure that a constant fresh supply of clean water is available – housed ewes on dry feed can consume as much as 6L of water per head per day in late pregnancy and even more after lambing. If water supply to the ewe is limited it can seriously suppress her appetite.

A proper feeding regime in late pregnancy can make the lambing season more productive.  If you need more information on concentrate feeding levels pre-lambing contact your nearest Teagasc Office.