Understanding Feedlot Blends

Starter Blends

Newly arrived calves do not readily eat upon arrival in the feedlot. On day one in the feedlot, only 22% of the calves may eat. By day three, approximately 40% may still not be eating. And on day 10, an average of 15% of the cattle may not be eating. Starter rations should be fed for 3-4 weeks after arrival. The actual starter ration should contain from 60% to 80% concentrates. If cattle are destined for a high roughage program, the starter ration should be about 40-50% concentrates.

The starter ration should contain about 16% crude protein on a dry matter basis, depending on intake. Dry matter (DM) intake is often less than 1% of body weight during the first week of arrival. Diet concentrations of protein and other nutrients need to be increased based on feed intake level in order to meet requirements. Recent research has suggested that up to 23% crude protein (dry matter basis) during the first week, comprised partially of a by-pass protein, can improve gains during the first week.

Animal sources of by-pass protein may be less palatable which means that a flavour enhancer such as molasses may need to be added. One thing to keep in mind when feeding receiving diets containing 70-80% concentrates, and high levels of crude protein is that these diets are highly digestible. Therefore, stools will be much looser than if the calves were being fed a diet with a high roughage content that was less digestible. The loose stools clear up in approximately two weeks and should not be confused with a diarrhoea condition resulting in dehydration.

Calves are not initially capable of utilizing urea or other non-protein nitrogen sources very effectively. In addition, as urea decomposes in the bunk, as sometimes occurs in hot weather, it gives off an ammonia odour. Possibly, urea can be added up to 0.5% of diet dry matter in receiving diets, but higher levels may depress feed intake.

Provide about 3000-4000 International Units (IU) of vitamin A per kilogramme of dry matter. Receiving diets containing between 50 and 100 IU of vitamin E per pound may be adequate for most circumstances. Supplementing vitamin E through the diet appears to be more beneficial than by injection intramuscularly during the processing of cattle.

The B complex vitamins are generally produced in sufficient quantities in the rumen and the use of B vitamins has not consistently improved performance. However, if cattle have been off feed for some time, supplemental B vitamins, particularly niacin and thiamine may be beneficial. It has also been observed that calves fed supplemental B vitamins (600 mg niacin, 200 mg thiamine and 750 mg choline per head) plus vitamin E gained more weight than calves fed vitamin E alone.

The following table contains the nutrient recommendations for starter blends:

Some benefits may be realized by phase feeding diets which provide 20-23% crude protein during week 1, 17% crude proteins during week 2 and 14% crude protein in week 3. Protein concentration decreases as intake increases to provide the same amount of protein daily.

There is also a range of artificial supplements and medications that can form part of the starter blends to help calves increase their DM intake. A nutritionist should be approached to determine the supplements needed to obtain maximum weight gain in new calves.

Growth Blends

In most feedlots, there is very little if any distinction between growth and starter blends. The only real distinctions are adjustments in medication and supplements with cattle being allowed to eat as much as possible.

Some producers might also adjust the level of protein in the diets to slow down the rate of weight gain in cattle. Growth feeding normally means the cattle consume feed ad libitum (all they want). Some attempts to moderate daily intake fluctuations can be done with bunk management. Cattle can be put on forage, hay-based, silage-based or moderate gain level diets to grow at moderate rates of gain. These systems are well suited to many producers who are limited by facilities or by having abundant supplies of forages to use.

Finisher Blends

After the cattle have grown to about 340 kg, they are placed on high grain, finishing diets. These programs are best suited to medium frame cattle. This will allow them to finish at a heavier weight. Large frame cattle are better suited to high grain finishing diets following weaning. Although large-frame cattle can perform very well on forage-based diets, caution should have been considered since they will also finish at greater than desirable weights. Type of cattle, price margins, market conditions and feed supplies will dictate the optimum system for each producer.

Limit feeding strategies can also be applied during the finishing period and have two potential applications for cattle feeders. Backgrounders can limit intake of a high grain diet to achieve any rate of gain desired. This strategy should be considered when corn is a less expensive source of energy than hay. Limit feeding can also be used for finishing cattle to improve feed efficiency and increase carcass leanness.

Recent research suggests that feed efficiency may be improved if cattle are fed at intakes that are slightly less than ad libitum. In these trials’ cattle were fed 10-20 percent less feed than counterpart steers allowed to eat free choice.

Cattle were all fed to the same final weight (520 kilograms). Each 10% decrease in intake decreased the rate of gain by about 1kg per day. As a result, it took the limit fed cattle 15-25 days longer to get to market weight. However, the limit fed cattle used 50-120 kilograms less feed to achieve market weight even though they were on feed longer.

There were also advantages to limiting feeding in terms of carcass composition. Limit fed cattle had carcasses with 15-25% less fat than the full-fed cattle. This was achieved without decreasing marbling score or quality grade.

The system described above would provide little economic benefit for cattle feeders in today's marketplace. The improvement in feed savings would probably be offset by the need to feed cattle longer. This should change if a value-based marketing system were in place which rewarded carcass lean. The bottom line is that it may not always be best to allow cattle to set their own intake. By manipulating intake, producers may be able to improve feed efficiency, cut costs and produce a more desirable carcass.

Producers wanting to implement a limit-feeding program should make sure all the cattle can eat at the feed bunk at one time. Otherwise, dominant cattle will consume more feed than needed and probably incur acidosis conditions.

Finishing rations should have roughage levels of 10 to 15% on a dry matter basis so as to prevent potential problems if there is any processing. Ideally, it is desirable for the corn and the roughage to be mixed together to avoid sorting and digestive upsets. A coarse chop (greater than 6mm) is suggested for hay or silage. Bunk management is critical to reducing fluctuating intake and acidosis problems. Roughage is included in finishing rations to firstly contribute to the physical nature of the rations and, secondly, to provide nutrients.