Complementary feeding for optimal stock health
18/07/2007 8:24:48 PM
Colin Trengove BSc BVMS MVS CPAg, Pro Ag Consulting
Optimal pasture utilisation is difficult to achieve–especially in good feed years. However, it should be the aim of every grazier and can be assisted by complementary feeding of supplements over summer/autumn.
The three key factors to achieve optimal pasture use are:
- Growing as much dry matter as possible given the limitations of soil type, sunlight, rainfall, inundation and cost effective nutrient applications;
- Conversion of as much dry matter as possible to end product given the limitations of suitable stock numbers, grazing management, herd/flock structure/genetics and the management calendar, ie timing of calving/lambing etc.;
- Inclusion of appropriate supplements/animal treatments to improve pasture use.
The third key factor is addressed in the following. Many supplements and animal treatments are wasted due to:
- Poor timing of supplementation or animal treatment;
- Misunderstanding of animal requirements. Cattle, ewes and lambs all have different daily needs.
- Lack of knowledge of the nutritional status of various supplements.
A supplement must be a feed that complements the main diet or paddock feed. The idea of a supplement is to provide nutrients that are deficient or to provide alternative feed to improve stock performance.A common finding is that additional feed is being provided that has a similar composition to the feed already available in the paddock. For example, feeding lupin grain or lucerne or clover hay to stock on fresh pasture. This is likely to cause protein overload with potential disastrous consequences. This is not supplementation. Whereas, if high energy or low protein feeds were given, these would be considered supplements ie high energy - barley, maize, maize silage; low protein - barley straw, pasture hay.
For example, lambs or late pregnant ewes on dry pasture would be given high protein supplements eg lupins, canola meal, peas, beans, lucerne hay.
Analyse protein and energy levels
First you must analyse or at least know the protein and energy levels of your stored feeds. Even feeds of the same variety and origin can have totally different values for protein. See Table 1 below.
Once the feed value of your supplements is known, the timing and feeding of these can be determined based on the changing nutritional needs of stock throughout the year.
All stock require a balance of protein to energy in their daily diet. If this balance is maintained then minerals and vitamins become less important.
Refer to Table 2 below to see the protein and energy requirements of different classes of stock depending on their physiological state, age and growth rate. Compare these requirements with that which is available in common feeds listed in Table 1.
Knowing the protein and energy content of stored feeds and matching them to the protein and energy needs of livestock enables reasonable balance to be achieved in the protein and energy in their daily diet.
Protein is the most deficient nutrient during the dry months and energy and fibre are the limiting factors during periods of fresh growth.
Therefore, feed high protein in the dry and save low protein feeds for winter. Note: barley straw is of little nutritional value, but can be the most valuable supplement during periods of cold weather. It increases rumentation time, body heat and pasture utilisation. Don’t waste it with a match!
A strategy including soil, pasture and blood analyses will provide a more comprehensive diagnostic tool for disease investigation. More strategically, these analyses can be employed to effectively prevent production losses through the development of nutrient deficiencies or toxicities and illthrift.
An example of how this information can be used to advantage is designing a mineral mix or water medication to correct the imbalances or deficits apparent in the existing pasture based diet.
Similarly, the optimum requirements for livestock can be compared to the composition of manufactured mineral mixes to see how they rate.
Soil and pasture analysis is critical
Optimum feed utilisation is dependent upon adequate access to a balanced ration of energy and protein as well as minerals, vitamins and water. Analysis of the feed on offer and stored feeds is recommended to promote a balanced ration.
Comprehensive nutrient analysis of soil and pasture is critical in assessing the opportunities and limitations to achieving production targets in grazing ruminants. Implementing strategies based on regular monitoring of the nutrient status of soil and feed in the form of pasture or supplements or specifically formulated rations can effectively minimise production loss due to malnutrition or disease.
A critical step in undertaking soil and pasture analysis is to obtain good advice based on optimal rather than critical values for each nutrient analysed. Your advisor equipped with this information as well as knowledge of season, pasture availability, grazing management and the class of stock is then able to provide you with strategic production and management advice to optimise stock health and production.
Colin Trengove specialises in livestock health, production, and management with a special interest in nutrition. He provides a farm consultancy service to clients in south-east South Australia and western Victoria, and is a Director of APAL. Colin is a past national president of the Australian Sheep Veterinary Society and member of the Australian Association of Cattle Veterinarians, Australian Veterinary Association, and Australian Association of Agricultural Consultants.