How to positively influence lamb survival
Now that ewes are pregnant, the focus turns to maximising lamb survival to ensure the profitability of the sheep breeding system.
Ewes need to eat approximately 1.3 to 1.5 kg of dry matter of good quality feed to maintain body condition through the early to midpoint of pregnancy.¹
Scanning provides information on pregnancy status while helping to identify multiple carrying ewes who have higher energy demands. Also, it is an opportunity to physically body condition score (BCS) ewes.
Separate light ewes with a BCS of less than 3 and preferentially provide energy-dense, high protein feed over the next 30 days before the rumen capacity is restricted by the rapidly growing foetuses in the last month of pregnancy.
If a quality feed is short in supply, consider supplementary feeds such as grain, sheep nuts or dehydrated molasses blocks.
Foetal growth in the last 50 days of pregnancy is rapid and coincides with significant udder development for subsequent colostrum production and lactation. Rumen space is restricted, resulting in an inability to physically eat enough dry matter for the demands of the foetuses, especially when feed quality is average to poor. Feed restriction at this stage of pregnancy increases metabolic problems for the ewe and results in poor milk quality and quantity for lactation. With severe feed restrictions, ketosis (sleepy sickness) and hypocalcaemia (milk fever) can occur, resulting in higher lamb mortality and even ewe deaths. These problems are preventable through identifying at-risk ewes early and feeding them a highly nutritious diet.
Highly fecund flocks and storms sometimes require the rearing of lambs indoors. Managing issues such as low birth weight, low milk availability and mismothering will determine success.
Be realistic of your expectations if significant numbers of low birth weight, hypothermic and starved lambs enter the rearing system. Disease and mortality rates can increase when compared to rearing lambs of good birthweight and vigour, despite good nutrition and management.
The main problems in rearing sheds are often heavily influenced by human factors. Lambs are sensitive to poor hygiene of sheds and feeding equipment, frequency and volume of feeds, and sudden changes in diet. They also often have poor immunity due to not having enough colostrum intake in the first 12 to 14 hours of life. All these factors make them vulnerable to diseases such as abomasal bloat, diarrhoea, clostridial disease and navel ill.
To discuss feeding supplements to your ewes pre-lamb, contact your local PGG Wrightson Technical Field Representative.
1 Beef + Lamb New Zealand. Feedsmart Feed Table: Fact Sheet April 2017.
