Inadequate nutrition for ewes pre-lamb and early lactation can impact lamb survival and growth rates, and ultimately profit.

Ballance Sheep and Beef Programme Lead Richard Draper says a cost-effective way to provide enough feed to support ewes during this period is nitrogen (N) grown pasture.

“Soil N levels are typically low in early spring, but that is only part of the problem. In order to effectively utilise N, pasture needs plant available sulphate sulphur (S), which is also often lacking at this time of year.”

During cold, wet winter conditions, both sulphate S and N leach from the soil and bacterial production of sulphate S slows. If sulphate S is low when N fertiliser is applied, the pasture’s response rate (kg of dry matter (DM) per ha per kg of N per ha) will be lower.

Richard suggests planning ahead, monitoring pasture covers and applying N and S tactically. “To support good lamb growth rates, aim for at least 1,400 kg of DM per ha or 4 to 5 cm pasture height at set stocking.”

“There are alternatives to growing pasture to support ewes such as balage and barley,” explains Richard, “but you need to assess their suitability. Quality is important pre-lamb, as feed intake can be restricted due to compression of the rumen by growing lamb(s). Balage is typically lower quality than spring pasture with 8 to 10 megajoules of metabolisable energy (MJME) versus 11 to 12 MJME, so may not meet animal requirements and can cost more than N-grown pasture in spring.”

Concentrates such as barley may have a high energy content of around 13 MJME but are not always practical to feed and stock need time to transition.

To meet spring pasture’s N and S requirements, Richard recommends either Phased N Quick Start or the SustaiN Ammo range.

PhaSedN Quick Start combines PhaSedN with sulphate of ammonia, providing N and sulphate S, as well as elemental S. Elemental S does not leach and is gradually converted by bacteria into sulphate S, helping to address pasture’s medium-term S needs.

If elemental S is not required, the SustaiN Ammo range is a good option. SustaiN Ammo products support pasture growth by providing N and S in the appropriate ratio for the situation. All of the S content is sulphate S, so readily available for plant uptake. The inclusion of SustaiN reduces the amount of N lost as ammonia gas, and increases N efficiency. SustaiN also allows more flexibility in the timing of application as it does not need at least 10 mm of rain or irrigation water within eight hours to reduce losses as ammonia gas.

“With adequate sulphate S levels, N-grown spring pasture is a cost-effective and practical way of supporting ewes and driving performance during lambing,” says Richard.

For assistance soil testing and planning pasture fertiliser applications, contact your local PGG Wrightson Technical Field Representative.