Feeding In The Dry

Feeding In The Dry

During a prolonged summer dry period, using supplementary feeds to fill gaps in pasture supply or quality can be vital to maintain animal productivity and farm profitability.

Pasture offers a cheap and cost-effective feed that broadly meets the grazing animals’ nutrient requirements and can be managed to offer high productivity levels. However, the current hot and dry weather conditions often mean relying on stored or purchased feeds, says Ravensdown R and D General Manager Mike Manning.

“Identifying true nutritional shortfalls and meeting them at the lowest cost relative to the value of maintaining the animals condition or the improvement in productivity comes down to choosing the right supplement and correct timing.”

The two main effects of low soil moisture levels and warm temperatures on our pastures during summer are:
a) reduced pasture growth rates, which lead to less pasture (or dry matter) than necessary to meet stock needs
b) deteriorating or poor pasture quality which means fewer nutrients per kg of dry matter and reduced feed intakes. As a result, grazing animals require a greater proportion of their daily feed intake for maintenance leaving less available for production.

Pasture supply
There are three options to be considered when pasture growth is insufficient to meet animal demand:
1. accept the shortage and maintain stock numbers. In these circumstances animal productivity is compromised with reduced meat, milk or wool production per animal. In many cases, animals will use up body reserves for maintenance resulting in the loss of weight or condition.
2. reduce the feed demand by reducing stock numbers. This will result in greater productivity per animal than option one and is likely to have a positive impact on the reproductive performance of stock. However, low stock prices during dry periods and the cost of restocking must also be taken into account.
3. increase feed supply through supplementation.

“Under conditions where the shortage is likely to be prolonged or very severe, option one eventually becomes untenable because allowing stock to deteriorate too far will permanently affect their ability to grow or maintain pregnancy, as well as potentially becoming a stock welfare issue,” says Mr Manning. “Option two allows some reduction of feed demand, but in severe or widespread drought quitting stock can also become a difficult proposition.

“The key to using supplementary feeds in a drought is no different to the use of supplementary feeds at any other time: Make sure real deficits are being filled as cost effectively as possible.”

Pasture quality – nutrient supply
Energy tends to be the first limiting nutrient in pasture-based production systems. Consequently, supplementary feeding strategies for grazing animals are usually designed to provide additional energy. However, the deteriorating quality of mature or drought-stressed pasture means nutrients, normally provided by pasture alone, may no longer be available in sufficient quantities in a diet comprising poor quality pasture and/or other supplements. An example of this is the use of maize silage to dairy cows in the summer. Maize silage is low in protein (7% crude protein) at a time when pastures are usually low in protein (14-18%) and cows’ dietary requirements are around 16-18% crude protein for good milk production.

“Choice about supplement use when pasture quantity is limiting animal performance usually focuses on supplying additional energy at minimum cost. This strategy may not be effective if the diet is low in protein and the animals are unable to effectively use the energy supplied by the supplementary feed. Always purchase feeds that complement existing feed supplies. If high protein feeds are available on-farm, supplementary feeds which supply energy should be purchased and vice versa,” says Mike Manning.

“Regardless of climatic conditions, the aim of including supplements in the diet should be to complement nutrient supply, be it energy, protein or fibre, from pasture to achieve the desired (economically optimum) level of animal performance.”

Having a good understanding of the nutrient supply of the feeds you have available is important. Analysing the feed for nutrient content can help identify any potential deficiencies and ensure the feed is used efficiently.

A second factor to consider when choosing supplementary feeds is its effect on the potential intake of the animal. Although this is particularly important for high producing dairy animals, which rely on large feed intakes to meet their nutrient requirements for milk production, the principles apply to all ruminants. “Poor quality pasture will reduce the amount of feed the animal will be able to eat as well as reducing the amount of energy and other nutrients consumed in each kg of DM,” says Mike Manning. “As fibre levels increase, the time required to physically break down the feed (by chewing and fermentation) increases, slowing the passage of feed through the animal, reducing the potential feed intake.”

Reduced feed intakes result in reduced nutrient intakes. This, combined with the lower nutrient content of poor quality feeds, means a greater proportion of the daily nutrient intake is used for maintenance and subsequently fewer nutrients are available for growth and production, reducing feed conversion efficiency.

The value of different feedstuffs
In tight times or times of drought it can be tempting to purchase feed on the basis of cost per kilogram of dry matter (DM). But the dry matter alone does not give an adequate assessment of the nutrient supply to the animal and the value of the feed should be determined based on its ability to supply the nutrients in short supply on your farm. If you are short of energy, evaluate the feed on a cost per megajoule (MJ) of metabolisable energy (ME) If protein is in short supply then cost per kg of protein is going to be a better means of comparing different feeds. If you are simply looking for a filler and are prepared to forgo performance, cost per kg DM may be a consideration for you.

Substitution and wastage
Although less likely to be an issue in times of drought, it is worth noting that the addition of supplementary feeds to an animal’s diet can reduce the amount of pasture the animal will eat. This is known as substitution and can mean supplementary feeds offer less production than expected if not used carefully,” says Mr Manning.

When feeding supplements, minimising wastage (in any form) will go a long way towards reducing the overall cost of feeding per unit of production.

Economic analysis
Profitability of supplementary feeding through summer is not simple to calculate says Mr Manning. “However as a general principle, profitability will be affected by the cost of the supplement used and the value of any production generated (or maintained in times of drought). The closer the cost of supplement is to the cost of pasture the more profitable its use will be, and the higher the value of the production generated the easier it is to show profitable returns on purchased feeds.”

ENDS

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