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TAKING A LOOK AT LIQUID FEEDS FOR GROWING CATTLE

by: Stephen B. Blezinger
Ph.D, PAS

One significant challenge for nutritionists and cattle producers is to determine the ingredients, additives and feed processing as well as delivery systems that will improve performance and/or efficiency of growing cattle on pasture. An important consideration must be that the program should improve forage utilization in a cost-effective manner in a given situation. While countless combinations exist for providing the necessary nutritional supplements, not all are as economical as we'd like. Others require substantially more labor to utilize than is available. One of the options the cattle industry has come to respect to accomplish both is that of liquid or molasses based supplementation. Let's take a look at this method for growing replacement heifers and stocker cattle.

A common goal of many beef producers across the country is to breed yearling heifers to calve at two years of age. Interestingly, across much of the south U.S., cattle production systems have at least two major differences from other areas of the U.S.

1) It is commonly known that forage nutrition levels of warm-season forages in the south are lower than those forages grown in cooler and/or lower rainfall areas of the U.S. This tells us that more supplement is needed to grow heifers to meet the goal indicated above.

2) The use of some Brahman influence in most cattle reduces the proportion that reaches puberty by 14-15 months, i.e. Brahman crossed females take a bit longer to mature. This increases costs and reduces success so, in many cases, calving at two years of age is unprofitable.

To overcome these issues, producers are faced with added costs. These extra costs involve additional planting of annual forages, supplemental feeds, labor, facilities and supplies. Calving at two years of age requires a high level of management to be successful and profitable.

Nutrition is a key to successfully developing heifers and growing stocker cattle. Liquid supplements can be used effectively to supplement growing cattle fed forage-based diets. The challenge is designing liquid supplements to provide essential nutrients and additives that will improve performance at a reasonable cost. Let's examine several factors that must be considered.

Cane Molasses as a Source of Energy

Early research suggested that the feeding value of sugarcane molasses decreased when added at more than 10 percent of the diet. One study evaluated the net energy of molasses at different levels in beef finishing rations. The workers reported that in formulations containing 25 and 40 percent molasses, the net energy value was reduced by 49 percent when they were compared to feeding at only 10 percent of the diet. Another project suggested that molasses had a feeding value of 75 to 95 percent of the value of grain (i.e. processed corn) when added to the diet in smaller amounts. This value was reduced to 40 to 50 percent of the grain feeding value when added at higher levels. However, other, later studies indicated that the net energy value for finishing a steer did not decrease when molasses was added at levels above 10 percent of the diet. In more recent work it was concluded that most of the feeding data suggests the feeding value of molasses does not decline when added at 10 to 40 percent of the diet. What this appears to tell us is that when cane molasses is used at a maximum of 40 percent of the overall diet, no real reduction in feeding value is seen.

The feeding value of molasses supplements compared to corn-based supplements in cattle fed forage-based diets has been examined on numerous occasions. One such study evaluated molasses-soybean meal and corn-soybean meal supplements fed at 1.1 percent bodyweight of supplement dry matter (DM) to newly weaned heifers grazing Bahiagrass pastures during the summer. Results over two years showed that both molasses-soybean meal and corn-soybean meal supplements increased gains 0.21 lb. for each pound of supplement total digestible nutrients (TDN) consumed. When molasses (72 percent TDN) and corn supplements provided similar quantities of TDN, cattle with free access to hay had similar increases in gain. Hay consumption was reduced to a similar degree by both the molasses- and corn-based supplements. This is a common effect seen during supplementation with grains or molasses since either of these are more energy dense than forages.

Protein Levels and Source in Liquid Supplements Must be Considered

The crude protein concentration of sugarcane molasses is low (4 to 9 percent on a DM basis). Subsequently, it is necessary to increase protein levels in molasses-based products by one means or another. Remember from topics we've discussed in the past that one of the primary functions of feeding protein to cattle was to supply nitrogen to the bacteria in the rumen as well as the amino acids from protein to the animal itself. We term the protein fed to supply the nitrogen for the rumen bugs as degradable intake protein (DIP) since it is degraded in the rumen. Protein used to supply amino acids for absorption farther down the digestive tract are known as undegraded, escape or by-pass protein (UIP). In cow-calf and stocker production systems, a potential plan has been to meet rumen protein (DIP) needs first, then feed additional undegraded (UIP) proteins to meet protein needs of the animal when the response is economical. This means we need to develop a ratio of the DIP to UIP. Requirements for the DIP portion of the protein fed are generally met when the TDN to crude protein ratio is seven (or lower) to one for forage-based diets.

An interesting fact is that molasses from sugarcane grown on organic-matter rich soils has higher crude protein concentrations than molasses from sugarcane grown on soils low in organic matter. Since much of the molasses used in our feed industry is imported from other countries, it's difficult to make this assessment in advance. Higher crude protein values would indicate higher nitrogen levels in the product. However, of all the nitrogen cane molasses, protein and amino acids usually comprise less than 25 percent of the total nitrogen found in the product. Also, the availability of the nitrogen in molasses for microbial utilization may be in question. One study in 1993 indicated that 75-85 percent of nitrogen in molasses was available to microorganisms. This is not hard to understand when we consider that up to 75 percent of protein in sugarcane molasses is in non-protein-nitrogen forms with most as DIP and very little (if any) UIP.

Liquid feeds are often fed to cattle grazing poor-quality standing pasture, range or crop residues. Nitrogen supplied by urea and other NPN sources is usually added to increase the low nitrogen concentrations in many molasses-based liquid feeds. In other words, to increase the overall protein content. Urea additions to increase crude protein in liquid supplements result in reduced consumption of liquid supplement at higher concentrations, which is usually desirable, and is cost effective. Urea is generally, however, not an economical means of limiting intake since other methods are available to accomplish this task. In most cases supplements containing natural protein from sources such as cottonseed meal or soybean meal usually give better results than supplements containing NPN from sources such as urea. Heifers offered molasses-urea blends may have lower performance due to lower consumption, but natural protein sources, such as cottonseed or feather meal, usually improve gains and pregnancy rates in heifers even if consumption and energy intake are similar. Growing cattle fed supplements containing NPN usually have better performance than heifers fed supplements with no added protein when the TDN to crude protein ratio is more than seven to one, but performance is often improved further when natural protein sources are used.

After DIP requirements are met, then UIP can be supplemented, if needed, to meet animal metabolizable protein requirements. A group of studies with growing beef cattle grazing warm season perennial grass pastures and hays has indicated that gains were usually improved when protein sources such as cottonseed meal, feather meal and blood meal were fed in or along with molasses-based liquid supplements. Feeding sources of less readily degraded protein to growing beef cattle improved performance and may be profitable in some beef production programs.

What all this seems to imply is that better performance is realized when molasses-based protein supplements and protein sources such as cottonseed meal, soybean meal or feather meal were used in combination and effectively meet the needs of both the rumen bacteria and the animal itself.

Fat and Feed Additives Effective in Liquid Supplements

Nutrient and non-nutritive additives that improve cattle performance have been studied and discussed extensively. Both fat and antibiotic additives appear to be beneficial in some production systems and delivery in self-fed liquid supplements (i.e. lick-tank products) has advantages over other feeding methods, if effective.

An easy way to increase the TDN concentration in liquid supplements is to add fat. Fats blend well in molasses-based feeds and are palatable to cattle. Fat contents in excess of 10 percent have been routinely used in some free-choice products without separation as long as a small amount of suspension agent is used. A number of recent studies indicate that fat may have beneficial effects on reproduction in cattle above their energy value. A significant number of these showed an average increase of 17 percentage units in pregnancy rate. Additionally, a number of these studies also showed an increase in milk production for these same cows. One theory suggests that the feeding of these fats increases hormonal precursors used in the reproductive process.

Ionophores such as RumensinTM and BovatecTM are widely used to improve efficiency of gain in the feedlot industry. They have also been shown to increase gain (0.15 to 0.20 lb. per day) and feed efficiency in forage-fed cattle. Recently, another antibiotic, bambermycin (GainProTM), has been shown to increase gain in forage-fed cattle. Many cattle on pasture are not fed supplement daily, and the inability to deliver these antibiotics at effective levels in free-choice supplements has limited their use in grazing cattle. Liquid supplements provide an option to accomplish this task. Benefits of these additives include improvement of rate of gain and feed efficiency primarily through improved energy utilization (ionophores). These compounds have also been shown to have a positive effect on controlling coccidian in cattle as well. The Bambermycins did not appear to have this same effect on coccidia. The improvement in gains noted through the use of the bambermycins appears to be a result of stimulating more energy intake through decreased substitution of supplement for forage. In other words, when the supplement was fed, forage intake did not decrease as noted in the sections above.

Self-fed Liquid Supplements

Many ranchers prefer consumption-limiting supplements that can be self-fed to grazing cattle. Labor savings from the reduced feeding are important in many situations. Hand feeding has also been thought to change grazing behavior (cattle wait for feed supplement to be fed instead of grazing). Liquid supplements are designed to be completely blended mixtures that cannot be sorted by cattle. This allows the addition of micronutrients and drugs with increased effectiveness and reduced risk of excessive intake. Designed appropriately, liquid supplements can be self-fed, avoiding the cost of intake limiters, such as salt, that are often used in self-fed dry supplements.

Consumption of both liquid and dry self-fed supplements is variable and situation dependent. Intake depends on the cattle, forage, weather, water, availability of shade and/or loafing areas etc. Many of these factors are changing constantly so consumption keeps changing. Average consumption of the herd can be measured, but there is considerable variation between individual animals.

Conclusions

Liquid supplements can be formulated to effectively deliver energy, protein and other essential nutrients for stocker cattle and growing heifers. Feeds or feeding programs that provide undegraded intake protein (UIP) in addition to the ruminally degraded proteins (DIP) often improve the performance of growing cattle grazing medium- or low-quality forages. As with all supplements, liquids do have their limitations but in general appear to be a cost effective method of supplementation.

Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulphur Springs, TX. He can be reached at P. O. Box 653 Sulphur Springs, 75483, by phone at (903) 885-7992 or by e-mail at sblez@peoplescom.net.

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