Applied Swine Nutrition Basics.
Part 1. Theory. Muscle Growth, Ration Energy Density & Ambient Temperature.

Absolute & Relative Energy Value of Protein & Energy Sources - Dry Matter Basis.

Feedstuffs Table 1. Absolute Energy Values (Swine), Kcal/Kg for Protein Sources.

Feedstuffs Table 2. Percent Lysine & Relative Energy Compared to Soybean Meal.

Feedstuffs Table 3. Absolute Energy Value (Swine), Kcal/Kg for Energy Sources.

Feedstuffs Table 4. Percent Lysine & Relative Energy Values Compared to Corn.

What we're really interested in with growing pigs is the amount of dietary energy that is available for growth of the pig. The above table suggests which feeds are best in supplying net energy. Please understand that (1) the number of calories in the energy source (2) needs to be compared to the cost of the ingredient that supplies it and (3) the production of the pig estimated to determine which ingredients are your best buy. That can be done with the Pig Profit Planner. This is explained in Part 3 of this manuscript.

Studying the crude protein, lysine and relative energy levels of the various protein and energy sources shown in the above table will help you make informed decisions when substituting one grain for another. The same table will help you make protein choices.

Each one percent increase in the ration crude fiber level decreases energy digestibility 3.5%. Feedstuff Table #1 shows that sunflower meal with hulls (SFMH) is very low in energy. While including SFMH in the ration of course reduces the calculated energy level, the actual energy level may be even lower because of the depressing effect SFMH may have on the digestibility of the rest of the ration. I have not adjusted for this possible effect and therefore the amount of feed necessary to put on a unit of gain may be greater than that shown for high fiber feeds. The following Feed Ingredient Table shows the fiber levels of typical sources of protein and energy used in Western Ukraine.

Feedstuffs Table 5: Crude Fiber, Acid Detergent Fiber (ADF) and Neutral Detergent Fiber (NDF) of Various Feedstuffs in percent

Crude Fiber is the historical method of expressing the fiber level of feeds. Two newer methods measure the amount of material left after treatment of the feedstuff (after subtraction of protein, fat and minerals). The results of these measurements are called (1) Acid Detergent Fiber (ADF) and (2) Neutral Detergent Fiber (NDF). NDF measures the cellulose, hemicellulose and lignin in the cell wall of the plant while ADF is an estimate of the amount of cellulose and lignin. The difference in the two shows the amount of hemicellulose in the feedstuff. The ADF method uses a stronger detergent and dissolves hemicellulose while the NDF method, using a weaker detergent, does not remove hemicellulose. In ruminants, NDF is the most accurate indicator of dry matter intake.

The effect on feed intake and hog performance from diets high in fiber is dependent on ambient temperature. During periods of low temperature, low energy (high fiber) diets tend to support growth rates equal to lower fiber (higher energy) diets but when the temperature goes up, higher fiber diets tend to depress growth rate. This is partly because it takes more of a high fiber source (such as sunflower meal with hulls) than a low fiber source (such as soybean meal) when higher levels of protein are needed for pigs fed in higher ambient temperatures. Feeding sunflower meal with hulls is not as depressing on animal performance for pigs fed in cold weather as in warm weather.

The change in voluntary feed intake that results when (1) the ambient temperature differs from the ideal temperature and (2) with feeds of different energy density, affects the percentage of crude protein (and lysine) that the ration must contain in order to be nutritionally adequate and to promote the most economical swine performance. Please read that sentence again and act on the economic fact that you need to change the percentage of protein in the ration as (1) ambient temperature and (2) energy density of the ration change and don't feed rations that contain more than 10% crude fiber. Here is why adjusting the ration is economically important.

The amount of protein (lysine and other amino acids) that animals of the same weight require is determined more by the amount of protein needed to grow muscle (fat free lean tissue) than by the need for protein for the pig to process the feed and thus as feed intake goes up (for pigs of the same size due to a decrease in the ambient temperature and a decrease in ration energy density) the percentage of protein needed in the ration goes down. This has real economic ramifications. Failure to understand and act on this concept will reduce your profit. We'll give examples with real figures in grivnia later.

Feeding one ration to pigs of the same size throughout the year is not economically prudent. Realizing this, I have formulated a series of five different rations that reflect the protein requirements for ambient temperatures encountered in Ukraine of +5 �C, 10 �C, 15 �C, 20 �C and 25 �C for each protein/grain combination that we want to consider. I realize that it gets colder than +5 �C in Ukraine but I'm hoping that it doesn't get much colder than that in the fattening barn. (You want to conserve heat in the hog barn but don't do so at the expense of fresh air as you don't want to suffocate pigs with foul air. The ammonia level is worse at the hog's nose and eye level than yours when you walk through the barn and evaluate air quality.) Determine the ambient temperature by taking the average of the high and low temperature for the day. The practical application of this knowledge suggests that rations should be adjusted seasonally rather than trying for weekly adjustments in a probably futile attempt to out-guess normal temperature changes that occur during a season.

The percentage of crude protein (plus lysine and other essential amino acids) required in specific rations can be determined by using a computer feed intake prediction model that considers (1) weight of the pig, (2) ambient temperature, (3) ration energy density, (4) square meters of floor space, (5) average daily gain of fat free lean tissue of pigs growing between 20 and 120 kg of body weight, and (6) the ratio of barrows, gilts and boars. I have purchased such a program that predicts nutrient requirements under the different conditions mentioned above and used it to generate some of the data presented.

What are the economic considerations of adjusting ration protein levels to match changes in feed intake that result from changes in ambient temperature? From calculations I made with a computer model I created using Microsoft Excel, a pig growing from 20 to 120 kg of body weight will consume 31% more calories if raised at 5 �C rather than at 25 �C ambient temperature. Without ration adjustments, feed costs obviously will be 31% higher/kg of pork produced at the colder temperature. Using present Ukraine ingredient costs, rather than a 31% increase in feed costs, you can significantly reduce the cost increase of producing pork by lowering the percentage of protein needed in the rations to meet the protein requirements of pigs raised in 5 �C temperature rather than in 25 �C. All of this assumes that all the rations are adequate in protein at 25 �C. This is probably not the case and if not, rations that may be adequate in protein when fed in cold temperatures because the pig eats more feed, will be deficient in protein at high ambient temperatures when it eats less feed. This will be reflected in more fat deposition and less muscle development by pigs fed in higher ambient temperatures. That's OK if you like salo but not good if you like to make a profit as it takes more energy and therefore more feed for a pig to deposit a kilogram of fat tissue than to grow a kilogram of muscle. The cost of feeding more feed/kg of gain can be offset some by the cheaper cost of the lower protein feed - if you lowered it. In the U.S. a hog carcass higher in fat brings less in the market place than a leaner one so feeding rations to pigs that are inadequate in protein will hurt you with (1) poorer feed efficiency and (2) a lower market price for the pig produced.

Looked at from the lower temperature side, pigs growing in a 25 �C environment, as compared to 5 �C, consume only 77% as much feed but still require almost as many grams of protein per day and thus the percent protein of the ration must be higher to meet the protein needs of the growing pig fed in a higher ambient temperature environment.

While we're talking about protein requirements, this is a good time to discuss how dietary protein requirements of growing pigs are determined by estimating average grams of protein accretion per day. (This section is mainly of academic interest as we aren't going to use this method to determine the percent protein needed in the ration. Instead I will use default values. You may read it if you're interested or skip it. Reading it will give you some good insights into what we're trying to do when we feed pigs for market.)

Historically, nutrient requirements have been determined by "feed'em" and "weigh'em" experiments and expressed as percent nutrient per kg of weight. After running a "zillion" of these feeding experiments at universities and commercial operations throughout the world, various parameters have been elucidated that can be used to predict nutrient needs adjusted to energy intake at different weights, square feet of floor space, ambient temperature, etc. To estimate protein needs, rather than by trial and error feed trials, you start by measuring the amount of muscle laid down by the pig since protein needs above maintenance can be estimated by measuring how much fat free lean tissue (muscle) is deposited during the growth period (from 20 to 120 kg. body weight). The genetic potential of the pig determines how much muscle the pig can grow when fed an adequate diet. Energy consumed above the need for maintenance and muscle growth is converted to fat. If inadequate energy is consumed, both muscle growth and fat deposition are compromised. (All performance data assume that you worm the pig.)

For real accuracy in determining the protein required in the diet of your pigs, you need to know the amount of muscle deposited during their growth period. This takes some rather sophisticated measurements at the time of slaughter to determine the amount of muscle in the carcass. From this number the amount of muscle assumed to be in the starting 20 kg pig is subtracted to find the net gain of fat free lean. Dividing the net gain in FFL during the growth period by the number of days the pig was on feed gives the average muscle growth/day. This number is entered into a computer model along with other parameters to determine nutrient requirements. The protein requirements I've used in formulating rations for hog raisers growing pigs in Western Ukraine are default values for pigs with a high-medium lean growth rate averaging 325 grams/day of fat free lean (FFL) carcass gain from 20 to 120 kg body weight. Dietary protein should be increased for pigs that have the genetic potential to grow muscle faster than this. If their genetic potential will not support muscle growth at an average of 325 grams per day, the protein level of the rations should be reduced to the amount that they need for their maximum muscle growth. Therefore, the dietary protein requirements can differ from herd to herd. The ability of your pigs to grow muscle determines their need for protein.

After measuring the amount of fat free lean (muscle) growth, you can determine the grams of whole body protein (not muscle) accreted by dividing the average increase in FFL per day by 2.55. This factor has been determined after running many experiments to account for all the protein needs of the pig including the need for protein to grow muscle, blood, hair, hide, hooves, bone, brain and central nervous system, internal organs, digestive tract, enzymes, etc. You can measure the carcass rather easily so by using the grams of fat free lean deposited per day and dividing this amount by 2.55 we can predict the average whole body protein accreted/day by the pig. It takes energy to grow muscle so we're assuming that there is adequate energy intake for the pig to realize its genetic potential for maximum muscle growth. Energy consumed above the pig's ability to convert protein to muscle is converted to fat tissue. Besides the expense of feeding more protein than necessary, this is not energy efficient as excess dietary protein must be deaminated and the nitrogen released excreted to make the energy of the original protein molecule available to the pig. If the diet is deficient in protein, the pig still eats feed and still gains weight, but deposits a higher percentage of fat tissue and a lower percentage of protein tissue.

The protein accreted by the pig as it deposits protein tissue contains 12.3 % lysine, so from the above method and making adjustments for the digestibility of the dietary lysine, the dietary lysine requirement above the maintenance requirement can be approximated. After determining the grams of protein and lysine required per day (you need to determine the amount of protein and lysine required for maintenance and add it to the amount needed for the accretion of protein), the percentage of each that needs to be in the diet can be determined by dividing the grams needed per day by the grams of feed consumed per day, which as we're discussed is affected by the temperature and the energy density of the diet. I haven't presented enough information here to do that but this will give you an idea of how the recommended amounts of dietary protein and lysine are determined (in lieu of running feeding trials) by measuring the muscle in the carcass. The ratio of the other amino acids needed in relation to lysine have been determined so if you know the lysine requirement (determined as shown above) the requirements for the other dietary essential amino acids can be estimated by multiplying the dietary lysine requirement times a factor determined to be appropriate for each essential amino acid.

From computer models you can determine the amount of muscle tissue and fat tissue that will be deposited by the pig at various body weights assuming an adequate intake of protein, energy, vitamins and minerals. By adding the grams of daily growth of muscle and deposit of fat tissue together and dividing by 0.94 (accounts for 6% of body weight gain being gut fill) the grams of gain by the pig per day can be estimated. Knowing the grams of gain and the grams of feed consumed, feed efficiency (which is a measure of the units of feed needed per unit of gain) can be estimated. Feed costs can be determined by multiplying the cost of feed per kg times the kilograms of feed consumed per day. This allows you to estimate the feed costs per kg of live weight gain and compare these costs to the market price for a live pig to estimate income over feed costs. Net profit can be estimated by subtracting non-feed costs from the income over feed costs.

There are some other values that may interest you. Understanding them will help you make correct management decisions. The protein concentration in muscle (fat free lean) is 23%, with the rest being mostly water, while the percent fat in adipose tissue is 90% (10% water). You can see that fat tissue contains 3.9 times more dry matter than muscle tissue. The amount of Metabolizable Energy (ME) required for protein synthesis is 10.6 kcal/gram of protein while it takes 12.5 kcal of ME for the pig to deposit a gram of fat. From these figures it is apparent that it takes a lot more dietary energy [(12.5/10.6) x 3.9 = 4.6)] to put on a kilogram of fat tissue than a kilogram of muscle (fat free lean) tissue. When this information is converted to feed costs, putting on gain as fat is usually more expensive than putting on gain as muscle, so you (1) want pigs with the genetic potential to grow lots of muscle, (2) you want to feed them just enough protein to support maximum muscle development and (3) you want to sell pigs after they begin to put on a lot of fat without much muscle growth. You can look at a pig and tell by its body appearance when it should be sold rather than fed to a higher weight. The "eye of the master fattens his cattle" and by your eye you can tell visually when you should sell a pig because it has stopped growing much muscle and is depositing mostly fat tissue. Don't feed a fat hog past when it is profitable for you to do so. Buyers may like lardy pigs as they use lard to make sausage. Even if you are still making money by feeding the pig (because the sale price is still greater than the feed and non-feed costs), it may be more profitable to sell the finished pig and restock with younger pigs that are depositing mainly muscle and are therefore putting on weight gain cheaper than is a fattening fat hog.

I've developed computer spreadsheets to report what happens in your hog raising program when the ambient temperature changes in five degree increments between minus 20 to plus 40 degrees centigrade (13 different temperature increments). From these spreadsheets you can learn the effect that ambient temperature has on energy intake, amount of feed the pig will eat, percent protein needed in the ration, animal performance such as average daily gain, feed efficiency, percent of muscle growth (fat free lean tissue) versus fat tissue deposited, profitability etc.

I've formulated a series of six rations (gestation, lactation and four rations for growing pigs) using feed formulation software that I created in MS Excel for each of the following ambient temperatures (temperature the pig experiences and not the temperature outside) of +5, 10, 15, 20 and 25 degrees centigrade using different combinations of feedstuffs. This amounts to substantially more than 100 rations. I will calculate more for specific requests. There are 30 rations each using combinations of (1) soybean meal and wheat, (2) partially dehulled sunflower meal and wheat and (3) sunflower meal with hulls and wheat. These three feed ingredient combinations times six rations each, times five ambient temperatures account for 90 rations. I have looked at additional ingredient combinations, such as for canola meal, meat and bone meal and even wheat fed without protein or with just lysine added until the feed level of the next limiting amino acid is reached. All calculations assume that vitamins and minerals are fed. If you want to really handicap a pig you can do it by not adding vitamins and minerals to its diet. This is a good way to assure going broke in the hog raising business. When the cost of ingredients is entered into the Pig Profit Planning (PPP) computer spreadsheet that I designed for market hogs, you can determine which feedstuff combination will make you the most money and predict how much you will earn at each of the five temperatures mentioned above (if you know the market price). The PPP is a significant management tool to aid you in making decisions on what type of ration to feed growing pigs with the ration recommendation sometimes changing as the ambient temperature changes.

Now is a good time to discuss in general terms what happens to hog performance, ration requirements and the profitability of raising pigs as ambient temperatures deviate from the ideal or optimum ambient temperature for growing pigs and to apply this information to the decision making process with the hope that this information will help you increase your profitability of feeding pigs to market weight. Remember, hogs must be wormed!

The figures in the following tables are for pigs (equal number of barrows & gilts) living in greater than 1.1 square meters of floor space/pig consuming rations that supply 3000 Kcal/kg of Metabolizable Energy (ME) gaining an average of 325 grams/day of muscle (Fat Free Lean) per day while growing from 20 to 120 kg of body weight. I have data for 13 different temperatures (minus 20 C to plus 40 C looked at in 5 C intervals) but will extract data from temperatures that reflect Ukrainian reality. I've supplied enough data so that you can study the effects of changes in the ambient temperature and draw your own conclusions rather than trying to memorize a summary that I might give to you.

Table 2: Feed Intake (Grams/Pig/Day) for Pigs Eating Rations Supplying 3000 Kcal/Kg ME

Table 4 shows that feed efficiency goes down as the temperature falls below the zone of thermal neutrality since the pig eats more feed as the ambient temperature gets colder (Table 2) while gaining about the same amount per day (Table 3). Above the zone of thermal neutrality, feed efficiency may actually improve because the pig, while gaining less weight per day, eats less feed so they tend to balance out. Temperatures of 30 and 35 �C don't have a significant effect on feed efficiency. Even temperatures of 40 �C do not significantly affect feed efficiency as the slower rate of gain is accompanied by less feed consumption when the ambient temperature gets hot. Pigs can do OK in hot weather.

Another important conclusion from studying Table 4 is that feed efficiency goes down as the pig gains body weight. This is because (1) as the pig gains weight it has more body to maintain and as we will see in a later table, (2) the weight gain results from a higher ratio of fat to lean than at lower weights. As you'll remember from earlier in this article it takes a little more feed energy to produce a unit of fat (12.5 Kcal Metabolizable Energy/gram) than a unit of protein (10.6 Kcal ME/gram) and since fat tissue is 3.9 times higher in dry matter (90%) than muscle tissue (23%), the combined effect is that it takes a lot more energy (4.6 x) to produce fat tissue than muscle tissue. This is reflected in (1) greater feed intake as the pig grows but (2) reduced average daily gain as the rate of deposition of muscle is reduced and the deposition of fat increases as the hog matures. More energy means more feed. Naturally, your first thought will be that this means more expense (greater cost per kg of gain) but after looking at the typical protein and grain cost relationships in Western Ukraine today, the cost does not go up as much as you might expect because the cost per kilogram of feed goes down as the pig matures because the protein level of the feed can be reduced and still meet the pig's requirement for protein. You benefit if you adjust the percent protein of the ration. All of these discussions assume that all rations are balanced for all nutrients at all stages of the market hog's life and that the level of protein in the rations is adjusted for the various temperatures shown.

(From a pork consumer's perspective, a fork full of fat contains 3.9 times as much dry matter as a similar fork full of lean meat. A gram of fat dry matter contains 9 kilocalories while a gram of protein dry matter contains only 4 kilocalories (same as carbohydrates). You can see that with the higher dry matter of fat tissue and the higher caloric density of fat dry matter compared to muscle tissue, eating the same amount of fat tissue compared to protein tissue really stuffs in the calories. Pure alcohol furnishes 7 kilocalories of energy so eating salo and drinking vodka is a wonderful prescription for gaining weight. If you're interested in losing weight or maintaining it, eat smart and get some exercise.)

Saying it again, from cost data that I've used in Western Ukraine, the cost per kg of gain goes up slightly as the pig matures, even though feed efficiency goes down, because the cost of protein is high in relation to grain and the reduced protein needs in the rations of maturing pigs offsets the cost of increased feed per kg of gain as the hog matures to market weight. Understanding this relationship emphasizes the need to adjust the protein level of feeds to meet but not exceed the protein needs of the pig. One ration does not fit all. But be careful! It is bad economics to cheat a pig on protein as you'll get a fat carcass, poor feed efficiency and reduced income as we'll see in later tables. A pig simply cannot grow more muscle than is supported by the lysine and protein consumed in the diet. There is no substitute for lysine and protein. The genetic potential of the pig to grow muscle determines the dietary protein requirement for pigs of similar size raised in the same ambient temperatures. In the U.S. fat pigs sell for less than lean ones. That may become the market situation in Western Ukraine. You'll know how to feed pigs when it happens. If you raise lean pigs, try to differentiate your product in the market place and get paid a premium for carcasses with a lot muscle and lower amounts of fat.

Table 5: Days Pig is on Feed in Each Weight Period & Total Days Needed to Fatten Hog for Market

Conclusion: The total number of days needed to grow a pig to market weight is similar when the ambient temperature is at or below the ideal temperature, but the days to market increase rather quickly when ambient temperature goes above the zone of thermal neutrality.

Table 6: Average Daily Gain from 20 to 120 kg, Grams

Conclusion: Ambient temperatures below the zone of thermal neutrality do not reduce average daily gain while temperatures above the ideal temperature reduce ADG. The ideal ambient temperature decreases as the pig matures. These data show that when the entire fattening period is considered, 20 �C supports faster ADG than 25 �C.

Table 7: Kg of Feed Needed per Kg of Gain to Fatten a Hog from 20 to 120 Kg BW

Conclusion: Feed intake/unit of gain goes up 31% when pigs are fed in 5 �C ambient temperature compared to when the temperature is 25 �C. Feed efficiency remains nearly constant for pigs raised in an environment above the ideal temperature. Moderate hot weather does not decrease feed efficiency of growing market hogs.

Table 8: Percent Protein Required in Complete Rations (3000 ME Kcal/Kg) at Various Ambient Temperatures

Conclusion: The percent of protein required in the diet of growing pigs goes down as the ambient temperature goes down because of a voluntary increase in feed intake (Table 2) at colder temperatures while the need for protein to maintain the pig and grow muscle does not go up as much. This can be stated in reverse. Diets that are just adequate in protein at cold temperatures will not contain enough protein when the ambient temperature goes up so it will be necessary to adjust (increase) the percent protein level of the ration as temperatures increase if you want to maintain good muscle growth, feed efficiency and not produce an overly fat carcass.

If you want to produce really fat hogs with lots of salo, feed them to heavy weights in hot weather without supplemental protein. Be sure to add vitamins and minerals however to all rations to meet the metabolic and structural needs of the animal. Look at the pig as a machine that needs vitamins and minerals in order to operate efficiently. Most vitamins and minerals serve as metabolic co-factors that facilitate biochemical reactions. Some vitamins and minerals are required for the structure of the pig such as for skin, hair, blood, bone, muscle, organ systems, central nervous system etc. Be sure to supplement grain and protein with vitamins and minerals so the pig machine can operate efficiently.

At the same ambient temperature, the percent protein required in the diet as pigs mature goes does down rather significantly.

Table 9: Percent Lysine Required in Complete Rations (3000 ME Kcal/Kg) at Various Ambient Temperatures

Conclusion: Same comments apply for lysine as given for total crude protein. While it doesn't show it here very well, the percent lysine required in the diet decreases faster than does the percentage of crude protein as the ambient temperature goes below the zone of thermal neutrality (Part 3). Adjust rations on protein per kcal of metabolizable energy.

Table 10: Percentage of Tissue Gain that is Protein Tissue.
(Reciprocal of % Fat Tissue Gain)

Table 11: Percentage of Tissue Gain that is Fat Tissue.
(Reciprocal of % Protein Tissue Gain)

Conclusion: Below the ideal ambient temperature the composition of gain (muscle growth vs. fat tissue deposition) remains similar for pigs of equal weight. Above ideal temperatures the ratio of muscle to fat tissue gain increases (if ration protein is adequate). Hot temperatures increase the percent of muscle that is deposited in relation to fat.

As the pig matures the percentage of the weight gain that is muscle decreases and the percent that is fat tissue increases.

Table 12: Feed Cost per Kg Body Weight Gain After Protein Level & Feed Cost Adjusted for Each �C Shown. Feed Cost/Kg Feed Shown is for 25 �C.

Conclusion: Feed costs per kilogram of gain go up on either side of the ideal temperature for pigs of a given weight. (See Table 1 for ideal �C.) Table 13 shows that the increase in cost is more for temperatures below the ideal temperature than for those above. Even though feed costs go down per kg of feed because of the lower percent protein required in the feed as the pig gains weight, the cost per kg of gain goes up for the maturing pig because it is putting on more fat and less lean (discussed above) and has an increasingly heavier body to maintain. I'm told by some hog raisers that some buyers want a heavy (200 kg) fat pig for lard that will be put into sausage. Remember that as the pig reaches maturity and its ability to grow more muscle subsides, the energy consumed is deposited as fat. Please notice again that as this happens, the cost of gain goes up. If this table were extended to higher weights, the cost per kilogram of gain would continue to increase and rather dramatically. The costs shown are for feed only. Non-feed costs need to be added in and they accumulate on a daily basis. There is a point where it is not economical to feed a pig to higher weights, even if the buyer wants lard to put in sausage.

Table 13: Feed Cost per Kg Body Weight Gain from 20 Kg to 120 Kg BW

Feed costs change of course as ingredient costs change so the absolute numbers shown above will change as price conditions in the market place change. The ratios are less likely to change unless the relationship between the cost of the protein source and the grain source change appreciably.

Conclusion: As ambient temperatures decline below the zone of thermal neutrality, the cost of a unit of gain goes up - BUT NOT AS FAST AS FEED INTAKE GOES UP or as fast as the increase in the feed required per kg of gain (shown in Table 7) if the percent protein of the rations is adjusted. The important point here (assuming the rations are adequate in protein at 25 �C) is that by adjusting protein levels down to match the new protein needs at the lower ambient temperatures, you can reduce the increase in feed costs versus feeding the same rations. For example, if we compare Table 7 that shows the kg of feed needed per kg of gain with Table 13, it is apparent that while the unit of feed per unit of gain goes up 31% when the ambient temperature falls from 25 �C to 5 �C, the actual increase in the cost of gain can be held at 16% as shown in Table 13 by adjusting the ration. Note that the cost of gain goes up only marginally as the ambient temperature goes above the ideal temperature. Heat isn't so hard on pigs. You can feed them economically in hot weather if you adjust (increase) the protein level of the ration so as to meet their protein needs so that they keep growing muscle tissue rather than depositing more fat. This keeps feed efficiency up as opposed to feeding rations deficient in protein.

From the field experience that I've had in Ukraine, there may be more of a danger that the protein levels are not high enough at the higher temperatures than there is a concern about dropping them at lower temperatures. Notice that the cost/kg of gain goes up slightly when the ambient temperature exceeds the ideal temperature as you need to increase the percentage of dietary protein to keep the pig growing muscle rather than depositing fat. Feed for profit! Try to keep the hog house warm in cold weather but be careful to keep the air fresh.

Here is a side by side comparison of the last two tables, which drives home the economic need to reformulate rations as temperatures change from season to season.

Table 7: Kg of Feed Needed per Kg of Gain to Fatten a Hog from 20 to 120 Kg BW

Table 13: Feed Cost per Kg Body Weight Gain from 20 Kg to 120 Kg Market
Weight if the Percent Protein in the Rations is adjusted to Ambient Temperature

All of these performance estimates are based on pigs that are wormed (so that you're feeding only the pig and not its parasites), that other good management practices are followed and that the pigs have the ability to grow muscle at an average of 325 grams per day from 20 to 120 kg body weight.

You may have seen some of these concepts in play during your experience of raising pigs. For example, it is common to see hog rations fed that are deficient in percent protein. When feeding such rations you may have observed that at cold ambient temperatures pigs grew muscle pretty well but on the same ration at higher ambient temperatures they seemed to fatten rather than to grow muscle. The material presented in this manuscript tells you why. Keep the percent protein in the ration adjusted properly to match the ambient temperature and the energy density of the ration.

I have heard people here say that they weren't going to feed pigs during the winter as they ate too much feed. They do eat more feed when it is cold, but if the rations were adequate in protein at the warmer temperatures, the increased feed cost of raising pigs in colder temperatures can be offset to a considerable degree by reformulating the ration with less protein. From a comparison of Tables 7 and 13 you can see that feed cost increases can be cut in half as ambient temperatures go below the ideal temperature by reformulating the rations to supply adequate but not excessive levels of protein.

(Cost comparisons shown are good for one set of ingredient costs - in these examples, Western Ukraine June 2002 - and depend on the relative cost of protein and energy. For example, if the cost of protein sources cost the same as the cost of energy sources, there is no feed cost difference as the percent protein of the diet is changed. Animal performance will be affected by protein adequacy so rations should be balanced for the protein required for given conditions irregardless of relative costs of protein and energy.)

I'm told that there is no price difference shown in the market place between a high lean heavily muscled hog and one with a higher percentage of fat tissue (less lean) so that there isn't an incentive in the market price to raise a lean pig. I'm also told that Ukrainians like to eat pork fat and that salo is the national delicacy. This supposed taste preference may have developed because historically pigs were fed rations significantly deficient in protein and what you got was a carcass with lots of fat and not a lot of muscle and thus culturally, fat pork became acceptable and with familiarity, even preferred. From a health standpoint, this is too bad as pork fat is not a health food. (And vodka is not medicine!) You need fat in the diet for satiety and good health but you should try to get it from sources higher in essential unsaturated fatty acids than in saturated fatty acids. The unsaturated fatty acids should be balanced in omega-3 fatty acids (fish oil, flax seed oil and canola oil) in relation to omega-6 fatty acids (peanut oil, soybean oil, corn and other vegetable oils) so that the ratio of omega-3 to omega-6 fatty acids is 1:1 or 1:2. One hundred years ago the human diet used to supply fatty acids in this ratio but with the increase in the use of corn and soybeans fed to humans and their animals (as opposed to more pasture intake) and food processing the ratio is more like 1:10 or even 1:20 and this causes a lot of health problems. (Omega refers to the non-acid end of the fatty acid and the number indicates where the double bond is located. Omega-3 means the double bond is between the 3^rd and 4^th carbon from the non-acid end of the fatty acid.) The ratio of omega-3 and omega-6 fatty acids influences which eicosonoids (eicoso means 20 and in this case means made from 20 carbon fatty acids with a specific number and placement of double bonds) are produced and these influence things of real importance for good health and enjoyment of life like immunity, mental health such as freedom from depression, inflammation of joints, susceptibility to cancer and heart attacks, function of the brain and eyes, skin and hair condition, etc. Avoid hydrogenated fats made by adding hydrogen with the help of a catalyst to break the double bonds of vegetable oils and raise the melting point, such as is done to convert vegetable oils to margarine and vegetable shortening used in baking and as happens when frying potatoes in oil to produce potato chips, etc. Reducing the intake of pork fat (and other saturated animal fats) and vegetable oils and increasing the intake of fish oils is considered beneficial for good health.

From my own observations watching Ukrainians choose pork from a buffet table, lean pork is chosen in preference to pork that is mostly fat. I suspect that the Ukrainian market place will begin to reflect this preference. Feed rations to pigs that support the growth of a maximum amount of muscle with a limited amount of fat deposition for improved profitability and market satisfaction. Adjust the ration percent protein based on ambient temperature, ration energy density and genetic potential so that this happens.

We've written how the protein needs of the pig can be estimated if we know the amount of fat free lean (muscle) that develops in the carcass during the growth period. Quick review: After determining carcass fat free lean by an examination of the carcass and subtraction of the amount of FFL in the pig at the start of the feeding period, the amount of net gain in muscle is divided by the days the pig was on feed to find the amount of FFL developed/day. This number (325 grams/day in our default equations) is divided by 2.55 to determine the amount of whole body protein accreted per day. This amount of whole body protein is divided by 0.23 as body lean tissue is 23% dry matter (77% water) to determine the amount of accretion of whole body protein tissue.

You may wonder how the amount of fat deposited is estimated. In theory here is what you do. First you use some complicated formulas developed from many experiments to predict voluntary metabolizable energy intake for each specific body weight and under similar environmental conditions. Then you subtract the energy expenditures for maintenance and muscle growth with corrections for temperature and limited floor space (if any) to arrive at the amount of metabolizable energy that is left for fat synthesis. When you determine this number in Kcal you divide it by 12.5, which is the number of Kcal it takes for the pig to produce a gram of pure fat. You then divide this number by 0.90 as fat tissue is 90% dry matter and 10% water. This gives you the amount of fat tissue deposited.

You can see that energy is used for all essential body functions first and what is left over is stored as fat so the animal can call on this energy bank later and make withdrawals if it encounters a period of energy deprivation. The amount of fat stored can be predicted by the above formula. If the protein in the diet isn't adequate to allow the pig to grow as much muscle as it is genetically programmed to do, the energy saved by growing less muscle is available for fat synthesis. Each extra 12.5 Kcal of energy will produce a gram of fat and this amount divided by 0.90 tells you how much fat tissue is deposited.

By adding the amount of total fat free lean synthesized and the amount of fat tissue deposited and dividing this number by 0.94 to account for the 6% of body weight gain that is gut fill, you can predict the number of grams per day of body weight gain. Since you know the energy intake per day and the energy content of the feed so that you can determine the grams of feed intake/day, it is a simple division of the number of grams gain per day into the grams of feed consumed/day to determine the grams of feed needed per gram of gain. To these numbers can be applied the cost of feed and by comparing it to the sale price of live pork in the market place you can determine income over feed costs. Subtract the non-feed costs (usually about 20% of total costs) and you can estimate the net profit (or loss) per pig and per kilogram of gain.

From an academic standpoint, it is interesting to compare the amount of energy (number of calories) needed to produce a gram of pure fat dry matter (12.5 kcal of metabolizable energy), versus that required to produce a gram of pure protein dry matter (10.6 kcal of metabolizable energy). What is interesting here is that a gram of pure fat when exploded in a bomb calorimeter produces about 9 kcal of gross energy while a gram of pure protein (after you subtract the energy produced by combusting the nitrogen in the protein = over one kcal but less than two), produces about 4 kcal of gross energy. It can be seen that it takes 12.5 kcal ME for fat divided by 10.6 kcal ME for protein = 1.18 times more metabolizable energy to produce a gram of pure pork fat compared to producing a gram of pure pork protein (fat free lean) dry matter. The reciprocal is 10.6 kcal ME/12.5kcal ME = 85% as much energy to put on a unit of pure protein (fat free lean) dry matter as to put on a unit of pure fat dry matter. You can see that there isn't much difference in the dietary energy cost to produce fat versus protein (fat free lean) on a dry matter basis.

Compare the relatively small amount of extra energy required to deposit fat versus protein (1.18 times) to the large difference in the amount of calories stored in fat dry matter versus calories stored in protein (fat free lean) dry matter. There are about 9 kcal stored in fat and 4 kcal stored in protein, which gives an energy yield in the carcass fat dry matter that is 2.25 times (9/4) the energy stored in an equivalent amount of protein (fat free lean) dry matter.

Obviously, it is more energy efficient for the pig to convert dietary energy to fat dry matter, than to convert it to protein dry matter (1.18 energy cost ratio to produce fat vs. 2.25 energy yield ratio - fat/protein - for the dry matter produced). This assumes adequate dietary protein and that the pig has the genetic potential to grow muscle.

Application. What does this mean for the relative feed costs to put on live weight gain as muscle versus fat tissue? Remember that fat tissue is 90% dry matter whereas muscle tissue is only 23% dry matter so while the energy cost to produce pure fat is only 1.18 times as much as to produce pure protein (fat free lean) dry matter, the feed cost to produce a kg of live weight gain is a lot more if the pig is laying down fat rather than if it is growing muscle.

Here are the numbers: Muscle is high in water (23% dry matter) while body fat is mainly dry matter (90%). For fat tissue gain, 1 kg of pure fat dry matter divided by 0.90 dry matter of fat tissue = 1.11 kg of live body weight gain/kg pure fat deposited. Compare this for muscle gain where 1 kg of protein (fat free lean) dry matter divided by 0.23 dry matter of fat free lean = 4.35 kg of live weight gain/kg of pure protein accreted. When evaluated on a per gram of dry matter deposited basis, live muscle gain is favored over fat tissue gain by 3.9 times for each unit of pure protein dry matter accreted versus an equal amount of pure fat dry matter deposited.

Let's put feed energy numbers to this. We have seen above that a pig will put on 3.9 times more live weight gain if it deposits a kg of pure protein (fat free lean) dry matter than if it deposits a kg of pure fat dry matter. The energy to produce a kilogram of protein dry matter (10.6 kcal ME) versus a kilogram of fat dry matter (12.5 kcal ME) is 85 percent (10.6/12.5). Therefore, for a given number of metabolizable calories fed, if there is enough protein in the diet (and the pig has the genetic potential) so that the energy can be captured by the pig as muscle instead of as fat, pig weight gain will be 3.9 divided by 0.85 equals 4.6 times more live weight gain per metabolizable calorie consumed. (Logic: There is 3.9 times more water in muscle tissue than fat tissue and it takes 85% as many ME kcal to lay down protein as fat. 3.9/0.85 = 4.6, which is the same value as given on page 11.)

You sell weight, so in managing your swine herd be conscious of body composition - muscle versus fat. Since it takes 4.6 times more feed to put on a unit of gain as fat compared to muscle, when a pig begins to fatten (primarily) rather than grow muscle, sell it and replace it with a younger pig that will grow more muscle than fat. Feed to maximize your profit. The eye of the master fattens his cattle.

Also of academic interest is the comparison of the zone of thermal neutrality for swine versus dairy cattle.

We discussed in detail at the beginning of this paper that the zone of thermal neutrality for growing swine is around 20 to 25degrees centigrade, based on body weight. You may remember that the ideal ambient temperature for growing swine can be calculated by:

Formula #1: 26 �C - (0.0614 times kg body weight)

The zone of thermal neutrality for breeding and lactating sows is 20 degrees centigrade.

The zone of thermal neutrality for dairy cattle is much wider than for swine, ranging from 5 to 20 degrees centigrade. A ruminant animal produces a lot of heat from rumen fermentation. Eating high fiber feeds increases the amount of heat produced by ruminants. When ambient temperatures rise above 20 degrees centigrade, milk production of dairy cows is compromised with the amount of milk produced decreasing as the ambient temperature increases.

Part 2 of this paper will give actual rations I formulated for use in Ukraine adapted to ambient temperature and energy density.

In Part 3, I discuss the Pig Profit Planner spreadsheet program that I developed for use in Western Ukraine that will help you answer the important questions of (1) how much profit or loss will I realize from feeding pigs and (2) which feed combinations will be the most profitable. Use it before you start feeding pigs.

Please study all three parts of this long manuscript and use what you learn to improve your profitability of raising pigs. Data presented are predictions using computer models that were created from copious amounts of experimental data gathered from many animal performance studies and are thought to be reliable. Genetic potential to grow muscle varies among pigs. I'd be pleased to hear from swine producers in Western Ukraine to learn of their experiences and to know if their results are similar to these predictions. I'd also like to hear how you're doing and to help where I can. Working with private farmers in Western Ukraine has been a pleasure. I look forward to continued cooperation.

Best wishes!

Roy

Roy E. Chapin, Ph.D. Animal Nutritionist
Cooperative Development Program
USAID, ACDI/VOCA and Southern States Cooperative
L'viv, Ukraine

Home Address: 11145 Chapin Lane, Amity, Oregon 97101 USA
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