- SECTION 1: PRINCIPLES OF DIET FORMULATION
- PRINCIPLES AND DECISIONS MAKING IN DIET FORMULATION
- SECTION 2: NUTRITIONAL COMPONENTS
- PROTEIN AND AMINO ACIDS
- MACRO MINERALS
- TRACE MINERALS AND VITAMINS
- FEED ADDITIVES
- UPPER LIMITS OF USAGE FOR FEED INGREDIENTS
- SECTION 3: NUTRITION PROGRAM BY PHASE OF PRODUCTION
- THE BASIC NUTRITIONAL PROGRAM
- SOW FEEDING MILESTONES
- DYNAMIC DECISION MAKING TOOLS
- CARCASS QUALITY
- FEEDINGS PIC PIGS UNDER SPECIFIC PROGRAMS
- FEED MANUFACTURING
- FEEDING SYSTEMS, FEEDER SPACE, DRINKING SYSTEMS
Energy is the most expensive component of the diet, representing about 50% of the total diet cost. Thus, an understanding of its roles on metabolic processes throughout the different phases of production as well as its performance and economic implications is important.
The utilization of dietary energy by pigs is illustrated in Figure 2A. Digestible energy (DE) is gross energy (GE) minus the heat of combustion of fecal material. Metabolizable energy (ME) is DE minus the heat of combustion of urine and gas production. Gas production in pigs is below 1% and is generally neglected. Net energy (NE) is ME minus the heat increment (HI), which is the heat of digestion and nutrient metabolism. Net energy is divided into NE for maintenance (NEm) and NE for production (NEp). Net energy for maintenance is the energy needed to sustain life and maintain homeostasis (i.e., body temperature). Net energy for production is the energy used in synthesis of protein, fat, fetal development, and milk synthesis. Thus, NE is the most accurate system to predict growth performance (Nitikanchana et al., 2015).
FIGURE B1. UTILIZATION OF DIETARY ENERGY BY PIGS.
Ingredients with high-fiber (i.e., DDGS, Midds) and/or high-protein (i.e., SBM) generate greater heat increment during digestion (Figure 2B), thus having a greater difference between DE or ME and NE compared with ingredients with moderate levels of fiber and protein. However, it is important to take into consideration that heat increment can be used by the pigs as a source of heat when they are below their thermoneutral zone. Thus, high-fiber and high-protein diets are not as detrimental during the winter season or in other situations where environmental controls can keep the growing pigs in their thermoneutral zone.
FIGURE B2. HEAT INCREMENT AS A PERCENTAGE OF METABOLIZABLE ENERGY (ME) FOR PIGS.
THE IMPORTANCE OF ENERGY AND INGREDIENT LOADING VALUES
The ingredient loading values used in diet formulation are of extreme importance. There are many energy systems and it is important to be consistent in the system used in your database. Table 2A shows ME, NE, and SID Lysine (Lys) levels for the same diet using two different ingredients databases: National Research Council (NRC, 2012) and Central Bureau for Livestock Feeding (CVB, 2008). There is a 3.3, 4.2, and 2.2% difference in ME, NE, and SID Lys. These values show the importance of using an ingredient database that accurately describes the specific region but also the importance of knowing locally the energy and nutrient content of the ingredients used in diet formulation. It is also important to know the ingredient loading values used in determining the pigs’ requirements. For example, different lysine loading values used in dose-response experiments will yield different requirements. Finally, it is important to know the moisture of the ingredients when determining energy and nutrient levels.
TABLE B1. SAME DIETS FORMULATED WITH TWO DIFFERENT INGREDIENTS DATABASES (NRC 2012 VS. CVB 2008).
Table 2B shows a corn-soybean meal based diet and a high-fiber ingredient based diet formulated to have the same level of ME. Note that even though the diets have same ME, the high fiber ingredient diet has 2.5% less NE. These could result in 2.5% worse F/G (Nitikanchana et al., 2015). Therefore, scenarios where high fiber ingredients are pricing into the diet, the differences in NE should be taken into account when conducting the economic calculations.
TABLE B2. DIETS WITH SAME METABOLIZABLE ENERGY (ME) BUT DIFFERENT NET ENERGY (NE) WITH NRC (2012) INGREDIENT VALUES.
RESPONSE TO ENERGY LEVELS IN FINISHING DIETS
Table B3 is a summary of growth trials from PIC280, PIC327 and PIC337 sire lines. All sires were bred to PIC Camborough® sows.
Pigs were assigned to a series of high-energy diets (corn, soybean meal, 6% DDGS with 4.5% added fat, NRC ME ranged from 3408-3455 kcal/kg, from 27 kg to market) or a series of low-energy diets (corn, soybean meal, 6% DDGS, no fat, 16% wheat midds, NRC ME ranged from 3150-3410 kcal/kg from 27 kg to market, respectively. Diets were balanced on a SID Lysine:Mcal ME basis according to PIC recommendations. Minimum SID AA ratios of AA were maintained in all diets. Diets are shown in the Appendix A.
TABLE B3. RESPONSE TO HIGH- AND LOW-ENERGY DIETSa.
In this trial, feeding a series of high-energy diets resulted in a faster ADG by 3.5% (P < 0.0001), a lower ADFI (P < 0.0001) and improved feed conversion by 11% (P < 0.0001). Lifetime daily carcass gain was increased (P<0.05) in pigs fed high energy vs low energy diets.
However, the caloric efficiency was similar (P > 0.5) among the high-energy (8774 kcal ME/kg gain) and low-energy (8840 kcal ME/kg gain) diet series. This information demonstrates that the same daily calories were consumed and the same amount of calories was used to deposit the same amount of weight gain. Though the feed conversion was different, the pigs on the lower energy diets were not necessarily less efficient in energy utilization. There was no sire line x dietary energy interactions in this trial.
The results indicate PIC pigs perform well across a wide range of energy intakes and adjust well to+ dietary energy level. Results also indicate that PIC pigs also remain very efficient going to heavy market weights as indicated by the growth curve results. The growth curves for each sire can be requested to your account manager.
It is important to note that low energy diets will cause an increase in feed intake up to point where gut capacity becomes a constraint (Figure 2C) and energy intake per day is reduced. Additionally, when using low energy diets, it must be communicated to all production personnel so that they can allow for proper feeder/pen space and feeder adjustments to insure the growing pigs can reach these intake levels. Restricting feed intake below this point will reduce pig performance. More information on feeder space can be found in the PIC Wean to Finish Manual at http://na.picgenus.com/resources.aspx.
FIGURE B3. EFFECTS OF NET ENERGY INTAKE PER DAY BASED ON DIFFERENT NET ENERGY PER KG OF DIET (ADAPTED FROM STEIN AND EASTER, 1996) .
To decide on the most economical NE level for a specific production system one needs to consider the changes in performance expected by the changes in NE level and the cost related to those dietary energy changes. It is important to emphasize that a large amount of the value of growth response to energy depends on having adequate levels of amino acids.