Feeding just straw (regardless of volume) to any class of cattle will not meet maintenance requirements and stock will lose weight. Straw is low in digestibility which restricts daily intake and has a very low protein and energy content.
Check the pasture growth rate (PGR) and Feed-On-Offer (FOO) on your property using Pastures from Space tool. Another tool Deferred grazing calculator will help determine how many days is required to meet a pasture target at a particular pasture growth rate. You will need to continue supplementing your lactating cows until the green FOO is around 1000kg DM/ha.
Transitioning cattle onto grain
Due to their high protein and energy levels, grain and pellets are effective concentrate supplements during the dry season to help meet the maintenance requirements or production targets of cattle.
Transitioning cattle onto these supplements must be done carefully to minimise the risk of grain poisoning (also known as ruminal acidosis). Ruminal acidosis is most likely to occur when stock are introduced to supplements which are low in fibre and have a high starch content before the ruminal microflora have had time to adjust.
Different commercial brands of pellets have varied fibre and starch contents, and the transition period required between different brands will vary. Always check and comply with manufacturer’s instructions.
Suggested transition program for mature cattle:
- We are aiming to start with a low volume of concentrate and increase to the full ration over a period of 14-21 days to give the rumen microflora sufficient time to adapt to processing these higher starch feed sources.
- Ensure cattle have consumed roughage before being exposed to the supplement.
- Roughage should remain at least 30% of the provided ration to ensure good rumen function – start with a higher proportion of roughage and this can be decreased as the volume of supplement is increased over this transition period. Some producers find that providing ad lib straw is suitable in this scenario.
- Start with 0.5kg/head/day of supplement for the first three days and then increase by 0.5kg/head/day every third day until the desired volume is reached.
- After the desired ration is reached then feeding may be reduced from daily to every second day (that is, feeding both days’ worth of feed in one feed) if desired.
- Not all supplementary grains are interchangeable as the amount of starch and fibre varies between different grains and the rumen may not be able to cope. For instance, if cattle are accustomed to supplementary feeding with oats, then they should not be immediately swapped to wheat at the same volume. Some farmers will shandy a small proportion of the new grain with the old and transition to the new feed source over a week. If there is no original grain source remaining, reduce the concentrate supplementation volume to half what is currently being fed, and work upwards in 0.5kg/head increments every three days.
It may take 5 to 10 days for stock to recognise the supplement as a feed source if they have not been exposed to grain or pellets previously, and concentrate amounts should not be increased until the cattle are consistently eating the provided ration.
Be on the lookout for shy feeders who may not be eating their portion of the ration – they may need to be separated out and managed separately.
Producers should be guided by any clinical signs in response to the ration to minimise the risk of clinical or subclinical acidosis. Producers should not increase the proportion of concentrate in the ration and should remove stock to good quality hay until clinical signs are resolved. Acidosis during the transition period is most common in dominant ‘greedy’ animals who eat a high volume of the concentrate.
Clinical signs of acidosis include sudden death, scouring, whole grain visible in faeces, lameness, bloat, staggery gait and collapse. If these signs occur, contact your veterinarian. Subclinical acidosis, also known as chronic ruminal acidosis, is more subtle and will not cause deaths, but will be production limiting for the stock due to damage to the rumen. Clinical signs include diarrhoea, reduced appetite, lethargy, and lameness.
Supplementary feeding with grain or pellets may be a risk for pulpy kidney disease (enterotoxaemia) due to changes in the gut microflora and rate of passage of feed through the gastrointestinal tract. Prior to commencing supplementation, producers should provide a dose of a clostridial vaccine.
Feeding sites
When pasture availability is low and ground cover reduces exposing the bare ground and soil, sand ingestion can become a lot more prevalent. While not always avoidable, feeding livestock in sandy areas can lead to and ingestion, disrupting the normal rumen function and in severe cases, resulting in death. To limit the amount of sand ingested, it is recommended to utilise lick feeders, troughs and hay racks.
Elevating feed results in greater feed efficiency as feed is not lost in sand and dirt, as well as limiting the spoilage caused from animal compaction and defecation.
Weather damaged/mouldy hay
It is not recommended to feed weather damaged hay. Weather damage results in wet areas in the bale that lead to spoilage through accelerated decomposition and the development of mould. Spontaneous combustion is also of concern.
Spoiled hay will have lower energy and protein levels, and palatability will be affected, reducing intake by the stock. There will be a higher wastage percentage and producers often underfeed stock by presuming stock are not hungry due to the high levels of wastage remaining in the paddock.
There are a range of moulds (mycotoxins) that can form on damaged hay or grain that will have a varied range of effects from chronic production loss, liver damage to death. Testing is costly and difficult as mould may be unequally distributed throughout the bale. There are no national standards or maximum limits readily available so interpretation of laboratory results to determine the safety of contaminated feeds is difficult.
Alternative or novel feeds
In dry times, when normal feed sources are scarce and feed prices increased, producers may look at alternative feeds for cattle. Unusual feedstuffs can pose a higher risk due to chemical residues, toxicity and contaminants, and producers should have feed analysed as quality and nutritional value can vary greatly. Visit our webpage Alternative energy and protein feed sources for sheep and cattle for more information. Agriculture Victoria's Drought Feeding and Management of Cattle book also covers a range of these unusual feeds, including nutritional content and considerations for feeding.
Feed additives
Feed additives are helpful adjuncts in developing a feed ration but are not a ‘magic bullet’ for fixing a ration if the underlying roughage and concentrate components are of poor quality.
Urea
- Urea can be used where there is a lack of dietary protein which is restricting the growth of rumen microbes.
- The high non-protein nitrogen (NPN) of urea provides a source of protein for the proliferation of rumen microbes. The creation of these microbes requires energy so energy must not be a limiting factor in the ration (e.g. combine with molasses).
- Urea can cause ammonia toxicity if fed inappropriately. Introduce into the ration slowly and ensure it is less than 1% of the total ration and less than 3% of the concentrate portion of the ration.
- Work up slowly and do not exceed a maximum of 0.1g urea/ kg body weight/day (50g/head/day for a 500kg cow).
- Urea should be supplemented with sulphur (N:S ratio of 10:1) so that sulphur is not limiting microbial uptake.
- With the increased population of rumen microbes as a result of the urea, the intake of the feed will be increased (the animal can eat a higher volume of the low-quality feed) – this may be up to a 20% difference in volume.
- Urea is primarily used on poor quality feeds to assist in reducing the rate of weight loss. For example, where the urea is added to straw, the amount of straw ingested by the stock will increase but due to the low energy content of the straw, the stock will still lose weight – just at a slightly slower rate. To ensure that the stock do not lose weight, the urea treated straw must be fed with a concentrate supplement.
Minerals
- If stock are severely deficient (e.g. cobalt deficiency), the amount of the mineral in proprietary mineral mixes will not be enough to correct for the underlying deficiency.
- Where nutrition is not a limiting factor and stock are a producer suspects there may be an underlying vitamin or mineral deficiency contributing to ill-thrift, veterinary investigation is recommended so that targeted treatment can be commenced.
Limestone
- Cereal grains are naturally low in calcium and prolonged feeding can reduce calcium reserves in the body. This is most significant for pregnant and lactating stock.
- Calcium should be added to the ration at 1% of the grain ration (e.g. 1kg limestone per 100kg grain fed out). Proprietary pellet formulations are generally balanced for calcium and further addition of calcium is not required.
Salt (sodium chloride)
- Cereal grains are also low in salt and sodium chloride can be added to the ration at 1% of the grain ration (e.g. 1kg sodium chloride per 100kg grain fed out).
- Addition of salt may increase the palatability of the feed but is not generally considered necessary if the water being provided has some salinity (whilst still being of acceptable drinking quality for livestock).
- Proprietary pellet formulations are generally balanced for sodium and further addition of sodium is not required.