Swine Nutrition Guide: Ingredient Quality

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Ingredient Quality -- Quality of the ingredients used in swine diets can have a large effect on performance. Test weight of grains, nutrient variability of byproducts and presence of mycotoxins all affect the feeding value of ingredients. However, when properly formulated, diets containing byproducts and weather-stressed grains can provide an economic alternative for swine producers.

What is the relationship between the test weight of grain and feeding value?
Most previous research indicates low test weight grains contain more protein and fiber and less starch and ME than normal grains, implying that low test weight grains have a lower feeding value than normal grains (Table 6).

However, more recent research on corn suggests there is a poor relationship between test weight and nutritional value. There is general agreement that pig growth rate seldom is affected by grain test weight as long as the test weight is not reduced by more than about 25%. However, if low test weight grain has less ME, pigs will compensate by increasing feed consumption, resulting in a poorer feed efficiency.

The negative effect on feed efficiency can range from 0 to 15%, depending on how much the test weight is lowered and which grain is fed. Fat can be added to diets containing low test weight grains to offset a possible reduction in pig performance.

In general, it is best to use low test weight grains in finishing and gestation diets (if they are free of mycotoxins) because older pigs use lower energy feedstuffs better than younger pigs. The feeding level during gestation may have to be increased to compensate for the lower energy value of the light test weight grain.

Also, include low test weight grains in the diet by weight, not volume. Therefore, scales on mixing equipment are necessary to make diets properly

Low Test Weight Corn
Corn weighing between 40 to 56 lb/bushel has the same feeding value for growing-finishing swine when compared on an equal moisture basis. When test weight drops below about 40 lb/bushel, growth rate and feed efficiency may decrease by 5 to 10%.

Low Test Weight Milo
Late planting, a cool growing season, or an early frost can lead to low test weight milo. It should be used only in growing, finishing and gestation diets. According to a recent study, there was no difference in gain or feed efficiency for growing-finishing pigs fed either 45 or 55 lb/bushel milo. However, feeding 35 lb/bushel milo resulted in 13% and 6% poorer feed efficiencies in the growing and finishing phases, respectively. For milo weighing less than 45lb/bushel, use local prices to determine what price the milo has to be to offset the expected poorer feed efficiency.

Low Test Weight Wheat
Research indicates finishing pigs fed 45 to 51 lb/bushel wheat were 7.3% less efficient than those fed 59 lb bushel wheat. When determining the economics of feeding low test weight wheat, assume it to have a feeding value of about 90% of normal wheat.

Low Test Weight Barley
In growing-finishing pigs, expect about a 5% increase in the amount of feed required per pound of gain for every 2.5 lb reduction in barley test weight from 49 to 44 lb/bushel, with an additional 7% poorer feed efficiency for 39 lb/bushel barley. If the barley is scab-infested, it should be fed only to growing-finishing pigs and limited to 10% or less of the diet. • Low Test Weight Oats Research indicates that low test weight oats can be fed effectively to finishing swine. Pigs fed diets containing 33% oats (32 lb/bushel oats) gained the same as pigs fed corn diets but required 5.1% more feed. Therefore, depending on economics, light test weight oats can be used in finishing diets.

Can I use high-moisture corn and frost-damaged soybeans in swine diets?
High-moisture corn (>18% moisture) will have the same feeding value as dry corn (12% moisture) on a dry-matter basis. Since high-moisture corn contains a higher percentage of moisture, a larger percentage of high-moisture corn must be added to a ton of feed to achieve the same nutrient levels achieved with “normal” corn. Also, it must be kept in mind that ensiled or organic acid-treated corn can not be sold at the elevator. It can only be used for livestock feed, so only make what can be fed in a year.

Extruded green soybeans have the same feeding value as extruded mature soybeans. Because of antigrowth factors (e.g., trypsin inhibitors), mature and immature raw soybeans must be heat-treated to inactivate these compounds before feeding them to swine. The only exception is gestating sows, which can use raw soybeans as the sole source of supplemental protein.

Factors to consider in determining whether to feed or sell your soybeans (mature or immature) and buy soybean meal are extrusion costs, shrink (8 to 10%), lower protein content of extruded soybeans, an improvement in feed efficiency due to fat addition, and trucking and storage costs.

Can I market my moldy grain through hogs?
Under certain adverse conditions, grains may become moldy. It is not the molds themselves, but rather the mycotoxins the molds produce that cause the negative effects. The main mycotoxins associated with grains are aflatoxin, zearalenone, vomitoxin (DON), fumonisins and ergot. Aflatoxins are found primarily in warmer climates, whereas zearalenone and DON occur in cool, wet conditions.

Aflatoxins suppress the immune system, cause a reduction in performance, and at high concentrations (1,000 ppb) death. Zearalenone will cause reproductive problems, infertility, high preweaning death loss and possibly abortions. Though zearalenone’s effects on growing and finishing pigs are minimal, it will cause prepubertal gilts to exhibit red, swollen vulvas and could affect future breeding.

Vomitoxin causes feed refusal with little effect on the reproductive herd. However, feed refusal associated with DON will result in a decrease in daily gain. Fumonisins can cause respiratory problems in pigs. Ergot occurs mainly in rye, wheat, barley, and triticale, and results in lactation failure and poor growth.

Recommendations are to keep all mycotoxin-contaminated grains out of breeding herd and starting diets, and not to exceed the following rates in other diets:

- Aflatoxin 200 ppb in growing- finishing diets
- Zearalenone 1 ppm in growing diets and 3 ppm in finishing diets
- Vomitoxin 1 ppm in growing- (DON) finishing diets
- Fumonisins 5 ppm Ergot 10% contaminated grain in growing/finishing diets

There are products available that will lessen the impact of aflatoxin (pellet binders, clays, etc.), but there are no products that can be added to swine diets to reduce the detrimental effects of zearalenone, DON, fumonisins and ergot. Drying the grain and adding mold inhibitors will decrease any further mold growth, but they have no effect on the mycotoxins already present.

Should I analyze the feedstuffs I am using?
Byproducts from the food industry such as soybean meal, sunflower meal, dried bakery products, etc. can be excellent feedstuffs for swine. However, since they are byproducts, they are more variable in nutrient content than grains. To ensure proper diet formulation, a nutrient analysis should be conducted on all byproducts used in swine diets.

Depending on the quality of soybeans used and the amount of hulls added back, the protein content of 44% CP soybean meal can range from 37 to 45%. Therefore, it is essential to know what kind of product you are working with before using in the diet. Submit a representative sample to an accredited laboratory and have it analyzed for the main nutrient(s) being provided by the byproduct. Consider a mycotoxin screen on grain when drought or wet growing conditions persist, storage problems are suspected, or certain abnormalities are observed in animals.

What are proper sampling techniques?
When sampling either individual feedstuffs or processed complete feeds for laboratory analysis, it is essential to get a representative sample. If using a grain trier/probe to obtain samples from a mixer or bagged feed, take at least ten 1/2 pound samples/ton of feed from different locations and combine them into one composite sample for analysis.

If sampling from an unloading auger, take at least ten 1/2 pound samples/ton during the entire unloading process, except for the initial and final outputs. Mix the samples, split them in half and send half of the composite sample in for analysis. Store the properly dated and labeled remainder in a freezer for reference.

Use the same techniques when taking a grain sample to test for mycotoxins except make sure the sample is sent to the lab in a either a paper or cloth sack. Using plastic bags or metal cans may cause mold growth to occur in transit.

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