As our understanding of pig energy metabolism improves, we can apply this knowledge to improve pig farm feed efficiency. The following ideas are derived from the discussions in this chapter:

  1. Manage pigs and pens well to reduce maintenance energy needs

Maintenance energy is a function of body weight as a variable, but is also affected by the frequency of activity of the pig, maintenance of function of the immune system and other systems that protect the pig from external factors (disease, stress, etc.), and thermoregulation.

  1. Increase the proportion of digestible energy in the total energy of the diet

Even in highly digestible diets such as corn and soybean meal, about 15% of total digestion is wasted in the form of feces. Producers can control this ratio by improving the digestibility of the diet by reducing the particle size of the diet, pelleting, adding exogenous enzymes, etc. As corn prices have increased, kernel size targets have declined; from a decade ago when corn kernel size was 750 microns, some producers now set their target size at 300-350 microns. Goodband et al. (2002) reported that every 100 micron decrease in the range of 1200-400 microns can increase the feed efficiency of fattening pigs by 4 points. Patience et al. (2011) reported that reducing the standard deviation of particle size from 2.33 microns to 1.88 microns can increase the energy digestibility from 81% to 85%.

  1. Test the actual energy content of farm rations

There is considerable variation in the value of digestible or metabolizable energy in any diet due to different raw materials, different digestive abilities of pigs of different ages, different particle sizes, different processing methods (granulation or powdering), etc. This makes it difficult for nutritional nutritionists to effectively manage the actual energy levels of the diet. A relatively easy and less expensive solution is to add 0.4% titanium dioxide as a digestive marker to the diet for 5 days. After 5 days, fecal samples from the pens (approximately 10% of the total feces) were collected. Analyze markers and energy in samples to detect true digestible energy levels in the diet. The resulting digestible energy can be used to estimate the metabolic energy value. One difficulty with this approach is pig coprophagia, which can cause errors in calculations. In practice, this impact can be reduced by adjusting the size of the leaks in the test pen floor.

  1. Feeding diets with low heat consumption during high temperature seasons reduces heat stress

Under normal conditions, the heat generated during the digestion and metabolism of food helps animals stay warm. However, in the high temperature season, heat is a negative factor affecting pig growth. In addition, pigs reduce feed intake through their own physiological regulation at high temperatures, which may be beneficial to health and physiological functions, but it also reduces growth rate and improves feed efficiency. Therefore, it is important to choose a diet formula with minimal heat production during high temperature seasons, which has low levels of protein and fiber, or a high fat content.

  1. Reduce the energy requirements of pigs to maintain health

We all know that immune system activation will increase the amount of energy gain that is maintained. Williams et al. (1997) reported that this can increase by 13%. Since health problems reduce feed intake and energy intake, they also reduce energy digestibility. Increased maintenance energy requirements are another factor in reduced energy efficiency. Disease can cause many problems in pig energy metabolism, all of which can lead to reduced efficiency. Therefore, it is very important for all pork producers to keep disease out of the barn because disease is very expensive to have.

  1. Utilize dietary energy for maintenance of pigs that require higher efficiency

Breeding for improved feed efficiency has now progressed to breeding for reduced maintenance energy requirements, a trend that will not only continue but become more complex. They will serve as tools for selection, our understanding of energy metabolism, and advance each other. Since energy maintenance needs to account for approximately 1/3 of the total daily energy intake, this provides a reasonable target for future genetic selection. We also know that there is variation among genotypes, so it makes sense to allow this type of selective breeding to exist.

  1. Prioritize feed intake

Just as the U.S. swine industry, and other countries around the world, are faced with accepting low-energy diets to reduce feed costs, the benefits of increasing pig feed intake are greater than people imagine. The results are shown in Table 10 below. Three models were designed in this study, using Cargill’s maximum pork growth model to reflect pigs’ responses to reduced dietary energy under different circumstances:

(1) Pigs can respond to the decline in dietary energy levels by increasing feed intake;

(2) The pigs cannot increase their own feed intake, so the daily energy intake of the pigs decreases, but they are fed to the same slaughter weight, but the days before slaughter are delayed;

(3) The pigs cannot increase their own feed intake, so the daily energy intake of the pigs decreases, but the number of days for pigs to be slaughtered is the same as in model 1, but the pigs’ slaughter weight is reduced. The results of the three models differ strikingly. If the same number of days to market is maintained as model 1, the market weight will drop from 132kg in model 1 to 123kg in model 3. If the same slaughter weight is maintained as in Model 1, the number of slaughter days will increase from 125 days in Model 1 to 139 days in Model 2.

There is no doubt that feed intake will be even more important in the future, even though it has been important in the past. Managing pens to maximize feed intake can help pigs adjust to low-energy diets to ensure normal daily energy intake. This also reduces the cost of harmless breeding.

  1. Develop feed intake curves for individual pens or production systems

The importance of understanding feed intake within a pen or system cannot be overlooked. Knowing the feed consumption data is not enough. Even if the data is correct, it only represents the average level throughout the growth period and is far from the optimal feeding plan. The growth model in point 7 above well reflects the benefits of knowing the feed intake curve of pigs. If the feed intake curve is known, then it is only necessary to know when and when the pig responds to a low energy diet.