How Can I Use My Own Cereals To Feed My Cows?
Harvest is coming and a lot of farmers are thinking to use whole cereals to feed their ruminant with the aim of decreasing overall food costs.
Whilst sheep can successfully utilise whole grains, the same does not apply to bovine livestock and to optimise nutrient digestion when cereals are fed, some processing of the grain prior to ingestion is required. This permits the ingress of rumen microbial enzymes. Grains can be physically processed by grinding or dry rolling whilst more recently, crimping of moist (immature) grain and treatment with a suitable preservative has been proposed. Various chemical treatments have been used of which sodium hydroxide appears to have been the most successful.
Grinding of cereals generally results in a relatively rapid rate of degradation in the rumen following ingestion. This inevitably increases the rate of production of volatile fatty acids (VFA) resulting in reduced rumen pH levels. At moderate to high levels of grain inclusion, this reduction in rumen pH may be sufficient to reduce the ruminal digestion of fibre, with consequential effects on total tract digestion of feed DM and level of feed intake. In worst-case scenarios, especially when the treated grain is fed in discrete meals, the outcome may be subclinical (> rumen pH 6.0) or clinical (> rumen pH 5.5) rumen acidosis. When clinical rumen acidosis occurs, irreversible damage to the rumen epithelium can occur whilst the production of microbial toxins and their subsequent absorption through a compromised rumen wall can result in death of the animal.
Rolling dry grains is considered to be less harsh compared with grinding but the process needs to be carefully controlled to avoid the grains being over-processed. When suitably processed, rolled cereals are considered to have a slower rate of digestion than ground grain but feeding high levels can still have undesirable effects on rumen fermentation principally through changes in rumen pH and the rumen microflora. Whilst both grinding and rolling of grain can be undertaken on farm (provided suitable farm equipment is available), the process of flaking grains has to be undertaken in a dedicated plant. This involves steam treatment of the grain followed by rolling and is likely to produce feed of similar digestion characteristics to ground cereals. In most countries, steam flaking is generally confined to the treatment of maize grain.
Crimped grain appears to have good intake and nutritional characteristics, provided moulding of the treated grain during storage does not occur. Its major advantage appears to be the ability to harvest immature grains, circumventing the need to wait until the crop is mature or to dry the harvested grain before storage. Such issues can be very important in marginal cereal growing areas, which is often where considerable amounts of home produced grain are grown for livestock feeding. An additive must be applied at the time of crimping to ensure safe storage and both biological and chemical based products have been proposed. Some manufacturers claim conferred benefits on nutritive value with specific additives but these appear to be marginal.
Urea treatment of moist wheat at harvest is a cheap and simple system, which preserves the grain and increases its crude protein content. Treated wheat can be fed whole without further processing. It consists of a concentrated solution of urea combined with an enzyme activation, ‘urease’, which on contact with moist grain works quickly to release ammonia which penetrates the heap of grain giving complete, long lasting protection.
Sodagrain is chemically grain treatment which reduces the degradation of starch in the rumen and increases the amount of starch entering the small intestines. Sodium hydroxide is highly caustic and can lead to safety issues if not used appropriately. However, its use is still permitted and provided suitable precautions are taken, it should present no major hazards to the farm operator. Furthermore, as the pH of treated grain drops quickly over the first 24-48hrs after preparation, due to the conversion of sodium hydroxide to sodium bicarbonate, the product is safe to handle after 2-3 days and should present no problems to the animal when fed after 4 days.
It is claimed that sodium hydroxide treated grain has a slower rate of digestion in the rumen than physically processed grain, there have been relatively few studies to quantify the possible impact of such on ruminal and post-ruminal digestion of starch and other nutrients. Compared with other methods of processing cereals, the sodagrain process has several nutritional benefits:
- The alkaline nature of the product helps buffer acidity within the rumen.
- The slow breakdown of the starch reduces digestive problems often associated with feeding high levels of cereals.
- Sodagrain when fed in a MechFiber ration improves level of production especially milk protein, milk yield and live weight gain.