Feed Budgeting
By Deb Scammell, Talking Livestock
Feed budgeting of supplementary feed and paddock feed is crucial this year for winter lambers. Due to the lower-than-average rainfall over summer and into autumn, and now wet and cold conditions pasture growth has been limited in many areas.
As ewes get closer to lambing (and particularly those pregnant with twins) their energy requirements nearly double from the maintenance energy they require when dry. Once they are a month post-lambing and at peak lactation their energy requirement increases significantly again. A twin bearing ewe (60kg) requires over 30MJ of energy at peak lactation compared to only 10MJ / day to maintain condition when dry. Unfortunately, in a season like this with limited paddock feed available this energy needs to be supplied through a large amount of supplementary feeding.
As soil temperature drops heading into winter the pasture growth rates become quite slow, often only growing around 5 – 10kg dry matter per hectare. This means with the days getting cooler it is going to be difficult for our pasture growth to keep up with animal demands, and even more so if paddocks are waterlogged.
Pasture growth rate can be improved by applying nitrogen, however soil temperature, moisture, fertility, and pasture species composition all impact on the pasture response. Moisture stress (i.e. too dry or too wet) will also have an impact and any other nutrients limiting growth (i.e. phosphorus or potassium) will also reduce the response to nitrogen.
Pasture grasses need to be able to grow to at least 3 leaf stage before they are grazed, cereals can be grazed slightly earlier as soon as they are tethered. However, it is important to be careful with ewes in late pregnancy or during lactation when they are moved onto very early, high moisture green feed. Often, they will chase green pick, which is still high moisture and has limited value to a very pregnant ewe and not go back to supplementary feed immediately. This can lead to pregnancy toxaemia issues especially with twin bearing ewes.
As we try and fill the current feed gap there are many supplementary feed options to meet energy requirements. High producing ewes (i.e. twin bearing) with high requirements must be provided energy dense feeds, along with high quality hay and roughage as they have limited rumen space, so it is important not to fill them up with low quality, fibrous ingredients. Make sure you look at feed tests of cereal hay before purchasing as quite a lot of last season’s hay is quite low in energy (ME) and very high in fibre (NDF) which means animals cannot consume enough of the fibrous feed to get adequate amounts of energy.
Vetch, lucerne or legume hay and high-quality cereal hay can be more useful during times of very high energy requirements or in high producing animals. Concentrated feed sources like Barley grain are generally recommended to supply energy and if overall ration protein were low, a legume would also be recommended to allow the ration to hit protein targets. During late pregnancy and lactation adequate protein is crucial to optimise lamb birth weights and allow the ewe to produce the required quantities of milk to achieve high lamb growth rates.
Full feed pellets can also be a useful and cost-effective option to satisfy high energy requirements and are especially useful for producers that are not set up for handling and mixing large quantities of grain.
Unfortunately, due to the delayed break it is important to look at supplementary feed requirements over at least the next 6 weeks as it is unlikely that pasture and paddock feed are going to meet requirements. Any feed gap will need to be satisfied by supplementing energy dense feed to minimise ewe losses and achieve optimum lambing percentages and reach lamb growth rate targets through to weaning.
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