A focus on pre-lambing feeding

The NZ sheep industry has been making enormous efficiency gains in the last 30 years:

The number of live lambs at birth, their survival rate and live weight at weaning has a major effect on the profitability of commercial sheep flocks and the satisfaction of lifestyle shepherds. Attention to detail in late pregnancy and after lambing is becoming increasingly important to improve the profitability and environmental efficiency of sheep. 

• It is important to scan ewe flocks at 45-90 days of pregnancy, splitting them up into: 
• Dries which can be culled, saving vital feed.
• Singles vs multiples, and early vs late lambing ewes.

Scanning enables better winter feed allocation according to BCS and pregnancy status with multiple bearing ewes, particularly those with triplets, as these can be identified and  lambed in sheltered paddocks and on the most ‘easy rolling’ terrain paddocks. If scanning is not possible, ewes should be fed according to condition and expectations of the size of the lamb crop based on the breed of ewe and previous crops.

Pre-lambing feeding has a major impact on lamb survival and lamb growth rates: 

• During late pregnancy, the growing lamb(s) increasingly take up more abdominal space, compressing the rumen and therefore, reducing feed intake. This is especially true for bulky slower digesting feeds like baleage, silage and hay, or feeds with a low dry matter (DM) content (e.g. below 15 percent).
• Although the lamb size at birth weight is mostly set at 90 days in pregnancy, the fat reserves are put on the lamb in the last 60 days of pregnancy. Lambs with more energy stored as fat at birth are better equipped to survive spells of bad weather in spring and maintain their suckling drive.
• When ewes are having multiple lambs they can easily lose condition, which is unseen in the last 2 months. This can cause sleepy sickness (ketosis/acetonaemia) but also reduces colostrum and milk production after lambing, negatively impacting on lamb survival. During the lamb’s first 4 weeks of life, 80 percent of its growth comes from milk production.
• Ewes having single lambs can become overweight when they are provided too much high quality feed and this can lead to lambing difficulties. This is best addressed by feeding them less or feeding bulkier feed between scanning and 120 days of pregnancy, but not in the last month before lambing.
• Selenium, iodine and the cobalt-containing vitamin B12 are transferred via the placenta to the lambs in the last 4-8 weeks pre-lambing and also after birth through the colostrum. Ensuring the ewe gets the right amount of each enables you to look after the lambs in the first 6 weeks of their lives and achieve good lamb survival and growth rates.

If ewes are not well fed over the last trimester of pregnancy, the growing lambs’ energy demands will be poorly met. This can result in several negative occurrences after birth, including: 

• Reduced colostrum quality.
• Poor ewe-lamb bonding.
• Total milk yield reduced.
• Immediately after birth, delayed onset to milk-let down.
• Reduced lamb vigour and survival.

Best use of supplements

Normal practice is to set stock the ewes 1-2 weeks before expected lambing on good quality pasture. In a situation of low pasture covers and growth, it is better to wait as long as possible with set stocking to prevent the ewes with lambs running out of feed in the first month. When feed is plentiful, twin and triplet bearing ewes can be managed as one mob, but when feed is in short supply triplet ewes should be drafted into a separate mob and prioritised for supplementary feeding.

If feed is short, triplet-bearing ewes should be prioritised for good quality ryegrass pasture at 11 MJ of ME/kgDM and a minimum height of 4cm (1200kg DM/ha), or high-quality supplementary feeding with nuts or grains. Bulky high fibre feeds like hay, average to poor quality silage, or bulb crops that contain lots of water are all best avoided. 

In the South Island, barley is commonly used to supplement ewes in late pregnancy, because of its:

• Higher energy content: 11.5-12.5 MJ ME/kg.
• Economics: lower cost per MJ ME than baleage.
• Less bulk and fibre: its intake is not limited by 'rumen fill.'

However, there are a few issues with barley. The quality can be variable and difficult to effectively feed out in the paddock, mainly in wet conditions. It pays to deal with a reputable supplier who can supply grain with good test-weights and low screenings.

Alternatively, you can use a balanced feed like NRM Sheep Nuts, which contain quality ingredients like barley, wheat, molasses, vegetable oil and also macro-minerals, trace-elements and vitamins. The pelletising process in the feed mill enhances the digestibility and the utilisation in the paddock and palatability is excellent. 

For high performing ewes bearing triplets or for ewes with twins at foot post-lambing, NRM Triplet Nuts contain a high level of balanced bypass protein and energy from carbohydrates and vegetable oil. With added minerals, trace elements and vitamins, Triplet Nuts have been designed to help to support the unborn lamb and its mother, while helping to provide more colostrum early on. Feeding should commence before lambing and be continued after lambing – especially for older, prolific ewes that may need extra supplementation. 

Supplementary feeding is generally more appealing to commercial farmers facing a feed pinch. Stud breeders, or commercial breeders with a stud flock within their operation, may be more prepared to invest in supplementary feed because their lambs are more valuable and a higher lambing percentage at tailing is an important measure of their genetic gains. Sheep owners on lifestyle blocks may not be able to check their ewes regularly during the day if they are at work and night-time checks become less appealing if lambing is protracted. A small investment in feed to help the health and vigour of ewes and lambs can be especially rewarding if fast lambings reduce the need to call for a vet.