Start the new year by getting sheep feeding on track

Recent weather has reminded us that no two years are the same. The winter of 2018/2019 was a dream in terms of grass growth, utilisation and general management, with ewes in prime condition.

In contrast, the inclement weather over the last few months, difficult ground conditions and resultant drop-off in grass utilisation has been challenging for ewes.

Taking swift action where required will deliver long-term benefits. It will be far more difficult and costly to address ewes entering late pregnancy in below optimum condition than it will to introduce supplementary feeding a few weeks earlier.

Many highly stocked farms in particular have responded by bringing forward planned housing dates, while others have started introducing silage or hay at grass.

The earlier introduction of silage and hay increases the importance of getting an accurate estimate of quality, so that feeding programmes can be tailored to meet ewe nutritional requirements.

Increased demand

The graph above details the average nutritional requirements for a twin-bearing ewe in good body condition and weighing in the region of 70kg to 75kg.

It is expressed in energy terms of UFL, where one UFL is defined as the energy contained in one kilo of standard air-dried barley.

A dry ewe or ewe in mid-pregnancy requires in the region of 0.8UFL to meet maintenance demands, while the energy requirement increases steadily in late pregnancy and jumps rapidly in early lactation.

This is why it is also vital to preserve grass supplies now and resist the temptation to regraze closed paddocks, as they will be much more beneficial in early lactation.

A ewe in mid-pregnancy will consume in the region of 1.15kg to 1.3kg grass DM, while, in early lactation, a ewe suckling two lambs will require 2.4kg to 2.5kg grass DM (spring grass has an energy content in excess of 1UFL per kg DM).

Getting back to forage quality, the graph below details the energy values of silage and hay of varying quality.

Access to silage with a high dry matter digestibility (DMD) will more than meet mid-pregnancy demands and deliver significant savings as ewes enter late pregnancy feeding.

Typical feed values

A high percentage of forage saved on Irish sheep farms typically falls below this level and tests in the region of 65% DMD to 70% DMD.

Access to ad-lib silage with a feed value of 67% DMD to 70% DMD will generally suffice to meet mid-pregnancy nutritional requirements, provided it has been saved well and is not too wet.

To consume 1kg dry matter of silage, ewes need to consume 5kg silage fresh weight at 20% dry matter or 3.5kg to 4kg fresh weight at 25% to 30% dry matter. Precision-chop silage will also promote higher intake over single chop.

Good leafy hay also has a good feeding value and this is boosted by the fact that ewes can consume higher quantities due to its higher dry matter and positive palatability.

Hay that has been saved from traditional hay meadows or similar quality pastures that were growing for an excessive length of time before harvesting or saved in poor weather will struggle to test much above 50% DMD. This should be borne in mind when feeding.

Feeding problems

Issues start to occur with poor-quality hay or silage. As well as not meeting nutritional demands, intake will be depressed and ewes will not be able to eat enough to meet nutritional requirements.

For example, if silage tested in the region of 55% DMD to 60% DMD and is wet, ewes will only be capable of consuming about 0.6kg to 0.7kg DM, which at such a low quality means ewes are only receiving about 50% to 60% of their daily nutritional requirements.

In such cases, weight loss can be in excess of 1kg liveweight per week. To prevent this from occurring, ewes will need concentrate supplementation or access to alternative feeds, such as feed buckets or molasses, to fill the energy deficit.

Offering in the region of 0.2kg to 0.3kg concentrates or a simple alternative such as straight barley, oats, soya hulls, beet pulp, etc, will suffice to fill the energy deficit in mid-pregnancy.

Late-pregnancy feeding

It is also important to note that concentrate supplementation will need to be introduced earlier where forage quality is poor.

The table above details the Teagasc guidelines for a twin-bearing ewe.

Concentrates should be introduced two weeks early and at 20% higher levels for triplet-bearing ewes or twin-bearing ewes lacking significant body condition. Likewise, supplementation can be reduced by 20% to 30% for single-bearing ewes.

Where silage quality falls below 60% DMD, then it is only really suitable as a roughage source, with nutritional requirements supplied by a high- or all-concentrate diet.

Previous studies have achieved positive results, with the supplementation rate increasing from 0.7kg 0.8kg in mid-pregnancy to 1kg seven to eight weeks out from lambing (depends on ewe condition) and rising to 1.2kg six to five weeks pre-lambing, 1.4kg four to three weeks and 1.5kg to 1.6kg in the final two weeks of pregnancy. Again, rates can be tailored for single- or triplet-bearing ewes.

Deferred grazing

Autumn grass has a typical feed value comparable to medium- or moderate-quality 70% DMD silage. The feed value of deferred grazing reduces to in the region of 65% DMD (approximately 0.72 UFL) from mid-January.

Depending on the length of time it has been growing, younger grass will have an energy content ranging somewhere between this and the feed value of spring grass (1UFL/kg DM).

The other big determinant to take into account with deferred grazing is the level of utilisation and grass dry matter.

Ground conditions are slowly improving with an upturn in weather, but utilisation is likely to remain in the region of 65% to 75%, meaning that ewes will need access to 1.5kg to 1.8kg grass DM to achieve an intake of 1.15kg to 1.3kg DM.