Optimizing Energy Formulation for Finishing Swine

Transcription

1 AJINOMOTO HEARTLAND LLC Optimizing Energy Formulation for Finishing Swine James Usry Roger Campbell Dave Burnham Heartland Lysine LLC Bunge Meats, Ltd. Heartland Lysine LLC Introduction The energy content of feeds is a major determinant of pig performance and consequently, is the single most important and expensive component of the diet. Therefore, from a financial point of view, it is important to accurately determine the energy value of ingredients. However, the most significant economic value for the feed formulator to decide on, is the total energy level of the complete diet. The objective of this paper is to review recent experiments designed to establish responses of pigs to dietary energy and to develop a simple model that estimates the economic value of energy in finishing swine diets. In other words - what is the most economic/ profitable dietary energy level to feed? Current Energy Systems Figure 1. Energy utilization in pigs (Noblet, 1995) Gross energy (100.0) Dce = 82% Feces (18.0) ME / DE = 96% Digestible energy (82.0) Urine (3.0) Methane (0.3) Metabolizable energy (78.7) k = 74% Heat (20.5) Net energy (58.2) The most commonly used energy systems today are digestible (DE) and metabolizable (ME). In Europe, thanks to Dr. Jean Noblet, the Net Energy Systems (NE) is now being widely used. Table 1 compares the different energy values of some commonly used ingredients.

2 If one were to take the approach that the energy value of an ingredient was a good indicator of the economic value of that ingredient, then Table 1 shows that tallow is worth between 2 and 2.5 times the value of corn and that wheat midds are worth between 60 and 70% of corn. This is the approach that most least cost formulation packages use and it is appropriate for a medium range energy diet (i.e. corn/sbm). It s simply a matter of replacing the energy in corn with a less expensive energy source. In the US, it is common to reduce the energy content of diets in finishing pigs in order to try and reduce backfat (Johnston et al., 1996). This recommendation was developed from data collected several years ago on genotypes that were not very lean and diets that may not have been adequate (i.e. not balancing the amino acids to the energy content of the diet). Is the energy value of a typical corn/sbm diet the most appropriate for the newer lean growth genetics? Table 1. Energy values for commonly used ingredients (Noblet, 1995) (Mcal/kg DM) DE ME NE Ingredients DE ME NE to corn to corn to corn Corn Wheat Tallow SBM Midds In the US, the ME system is the most commonly used. To justify a change in energy systems, one must see the benefit of such a change. However, with our present day practical formulations using corn and sbm, the NE system parallels the ME system (see Figure 2). As long as the two systems parallel each other there is really no benefit in changing from one system to the other. Figure 2. Energy system comparison Noblet, ME Energy (Mcal/kg DM) NE 6% Fat Corn/SBM 10% Wheat Bran ME NE

3 However, when the CP level of the diet changes, the NE:ME ratio does not remain constant. This is also true in Europe where by-products are commonly used ingredients. There will also become a time when the third, fourth and fifth limiting amino acids will become economical to consider in diet formulation in the US. Under these situations when the NE:ME ratios differ, a change from the current ME system to the more sophisticated NE system is warranted. Effective Energy System The Effective Energy System has not received the same level of attention as the other systems. The effective energy system differs in that it pulls out from the energy pool of the diet, the amino acids that will be deposited directly as protein in the animal. The remaining energy in the diet is then available to be used to drive protein and fat accretion and to maintain body functions. This is a modified NE system mainly used by modelers. It requires a lot of information about the diet as well as the genotype. Although current least cost software technology does not allow one to formulate diets using this system, the system can be used to evaluate diets once formulated (for more information see Emmans, 1994). Recent Energy Density Studies University of IL (Stein and Easter, 1996) An experiment was conducted at the University of Illinois to examine the hypothesis that carcass lean can be increased by diluting the dietary energy concentration of ad libitum fed finishing pigs. One hundred and fifty PIC barrows (approximately 54 kg) were allotted to one of five treatment groups. Five energy levels were examined (Table 2). All pigs were slaughtered at approximately 112 kg. Table 2. University of IL s experimental diets Diet # Ingredients (%) Corn SBM (48%) Soy oil Wheat Bran CGF Alfalfa Meal Vit&Mins Calculated Nutrients ME (Mcal/kg) T LYS (g/mcal) D LYS (g/mcal) The results from the experiment are shown in Table 3. Tenth rib backfat decreased from 21.6 mm (0.85 inches) on the high energy diet to 17.8 mm (0.70 inches) on the low energy diet. There was no significant difference in LEA across treatments. Therefore, the calculated percent lean increased from 50.5% to 52%

4 from the high energy treatment to the low energy treatment. It is interesting to note that the lower ADG s on the low energy diets were associated with a lower average daily lean gain. Table 3. Results from the University of IL growth experiment* Diet # Initial weight (kg) Final weight (kg) Average daily gain (g) Feed intake (kg/day) Energy intake, (Mcal/day) Gain:feed (kg/kg) Gain:feed (g/mcal) Dressing (%) 10th Rib fat (mm) Loin Eye Area (cm 2 ) Carcass lean (%) Avg. Daily lean gain (g) Tot. Lysine Intake (g/d) Dig. Lysine Intake (g/d) a 2.91 a ab 0.35 a a 21.6 a ab 392 a a 3.28 b a 0.32 b ab 21.8 a b 382 ab ab 3.36 b a 0.30 bc bc 19.8 ab ab 386 ab *Values with different superscripts are significantly different (P<0.05) bc 3.23 b 9.36 bc 0.29 c c 17.8 b a 358 bc c 3.31 b 8.93 c 0.26 d c 17.5 b ab 330 c The carcass yield was also significantly influenced by energy concentration (Figure 3). It should be noted that treatments 4 and 5 only contained 2.5 g Lys/Mcal ME whereas treatments 1, 2 and 3 contained 2.6 g Lys/Mcal ME. With this in mind, the pigs on the first three treatments were not significantly fatter at 10 th Rib (P < 0.05). They ate the same level of energy and grew at the same rate (P < 0.05). The FCR was improved by their adjustment in average daily feed intake. Spanish Study (Lopez-Bote, et al., 1997) 90 Carcass Weight, kg Treatment It should be noted that treatments 4 and 5 only contained 2.5 g Lys/Mcal ME whereas treatments 1, 2 and 3 contained 2.6 g Lys/Mcal ME. With this in mind, the pigs on the first three treatments were not significantly fatter at 10 th Rib (P < 0.05). They ate the same level of energy and grew at the same rate (P < 0.05). The FCR was improved by their adjustment in average daily feed intake.

5 Spanish Study (Lopez-Bote, et al., 1997) The effect of increasing the energy concentration of G/F pig diets through inclusion of lard on performance and carcass traits was studied. Seven hundred twenty Landrace x LW pigs (same number of males and females) initially weighing 30 kg were fed ad-libitum one of the two diets in Table 4. The animals were slaughtered at 90 kg. Table 4. Composition of experimental diets for Spanish Study Ingredients (%) Low Fat High Fat Barley SBM (44%) Sunflower Meal Lard Salt Limestone Dical VTM L-Lysine Calculated Nutrients Lysine (%) ME (Mcal/kg) Lys:ME (g/mcal) Table 5 shows that dietary treatment did not affect weight gain, but modified feed intake (P = ) and consequently, the FCR (P= 0.001). Dressing percentage (P = ) and carcass weight (P < 0.01) were higher in animals fed the high fat diet. Lean percentage was not markedly affected by dietary treatment. Backfat at the last rib was slightly higher in pigs fed the high fat diet, but not significantly (P =.08). Table 5. Results from the Spanish experiment* Sex Diet Gilts Boars Low Fat Hi Fat Initial wt. (kg) Final wt. (kg) Daily gain (kg/d) Feed Intake (kg/d) FCR Energy Intake (Mcal/d) Carcass wt. (kg) Yield (%) Last rib fat (mm) Lean (%) a a 0.68 a a a b b 0.73 b b b *Values with different superscripts are significantly different (P < 0.05) a 2.55 a a a b 2.44 b b b This study shows the same response as the University of Illinois data. The pigs adjusted feed intake to achieve a constant level of energy and consequently grew at the same rate. Carcass yield on the other hand increased with the energy level of the diet. Backfat also increased slightly by 1 mm (0.04 inches). PIC USA (Boyd and Johnston, Technical Report 48, 1997) An experiment was conducted with 240 PIC 327 x Camborough 22 progeny on feeding a high energy dense diet to G/F pigs. Castrate and female pigs of 25 kg were allocated to either a 3.3 or 3.5 Mcal ME/kg diet. A five phase feeding program was fed to127 kg (see Table 6).

6 Table 6. Experimental diets for PIC trial Control Energy a High Energy b Phase (kg) NRC ME Lysine NRC ME (Mcal/kg) (%) (Mcal/kg) a Contains % wheat midds. Corn-soy diet has 3.3 Mcal ME/kg b Contains - 3.5% added fat Lysine (%) Table 7. Impact of energy level on performance for PIC trial a Energy Level Item Control High Energy Start wt., (kg) Final wt., (kg) Gain (kg/d) b Efficiency (F/G) c Intake (kg/d) Energy intake (Mcal/d) c Start Pen CV (%) Final Pen CV (%) RTUS BF P2 (mm) b FOM BF (mm) b FOM loin depth (mm) FOM lean (%) b Carcass yield (%)* a 120 pigs allotted per treatment, sex balanced death loss, 5 total Covariate = end wt for RTUS BF; hot carcass wt as covariate for FOM b Energy level, P <.01 c Energy level, P <.05 *Personal communication (Mike Johnston, PIC USA); P=0.07 and end weight as covariate. The results of the PIC experiment are presented in Table 7. The feed intake of pigs offered both energy levels remained the same indicating that social or physical conditions within the pen kept the pigs from adjusting FI to a constant energy intake. This effect was not seen in the first two studies. In summary, the pigs on the high energy diet consumed more energy (P < 0.05) and grew faster (P < 0.01), FCR was improved on the high energy diet (P < 0.05), and FOM backfat increased by 3 mm (P < 0.01). Carcass yield was improved with energy density (P = 0.07). Bunge Meat Ltd. - Australia (Campbell, R.G., Internal Research Report, 1997) The experiment was designed to evaluate the effects of dietary DE content on dressing percentage. One hundred and fifty female pigs (3 replications/ treatment) with an average starting weight of 65 kg were allotted to one of five treatments (see Table 8). The pigs were selected based on age, weight and ultrasound backfat. The diets were formulated to 1.84 g available lysine per Mcal DE. The experiment was terminated when the first pen reached an average weight of 105 kg (49 days).

7 Table 8. Composition of experimental diet for Bunge trial Dietary DE content (Mcal/kg) Diet Ingredients Wheat Barley Canola Meal Hipro Meatmeal Tallow L-Lysine Threonine Other Min + Vitamins Table 9. Results of Bunge study (Pigs fed for 49 days) Dietary DE content (Mcal/kg) Significance (P = ) Daily gain (g) Feed intake (kg/d) Energy intake (Mcal/d) Feed:gain Final weight (kg) Carcass weight (kg) 676 b c 96.6 b 76.5 b 782 ab bc 99.9 b 79.8 b 826 a b ab 82.4 ab 825 a b ab 84.7 ab 876 a a a 85.8 a Dressing percentage (%) 79.6 cd 79.8 c 80.5 bc 81.0 b 82.0 a P2 (mm) 11.6 a 12.8 ab 14.3 b 13.9 b 14.1 b a,b,c,d Treatment means followed by a different superscript letter are significantly different (P <.05) 0.05 NS The results from the Bunge trial (Table 9) were similar to those from the PIC experiment in that pigs did not eat to a specific energy intake but rather to a specific feed intake. This is probably what happens under commercial conditions, when maximum feed intake is set by physical and/or behavioral factors. The results indicate that, the higher the energy density, the more energy pigs eat and the faster they grow. The better growth rate/throughput responses to the higher energy diets are likely to be more pronounced in commercial situations because feed intake is often limited by physical rather than physiological reasons. The closer an animal approaches its real energy demand, the lower the growth rate responses to dietary energy (R.G. Campbell, personal communication, 1997). The ADG response was most obvious at the two lowest energy levels, but FCR continued to improve linearly with increasing energy density (P < 0.05) to the highest level tested. Dressing percentage increased with energy density (P < 0.05). There was also an increase in P2 backfat (P <.05) but only from 2.9 to 3.2 Mcal DE/kg. P2 backfat remained constant from 3.2 to 3.5 Mcal/kg. Model Development From the research presented in this paper, it is safe to assume: When amino acids are balanced to the energy level of the diet, pigs of modern genotypes do not appear to become excessively fat with high energy diets.

8 Feed conversion is improved with high energy diets. If pigs eat to a constant level of intake, growth rate is increased. If pigs eat to a constant energy level, feed intake is reduced. In either instance, FCR is improved. Carcass yield seems to increase with higher dietary energy. This effect seems to hold true either if, pigs are fed high energy diets through both the grower and finisher phases, or just during the finishing stage (above 50 kg). This effect also seems to hold true whether or not pigs are fed to a constant weight or to a fixed number of days. End weight also does not appear to be a factor (studies from kg). These assumptions will form the basis of the simple economic model developed here. Prediction of carcass yield The effect of energy density on yield, for the four studies presented here is plotted in Figure 4. Two regression equations are presented for the University of Illinois data. As stated previously, the lowest two energy levels were not completely balanced to the same concentrations of lysine per Mcal of ME. Therefore, only the three highest levels of energy were used in the final analysis. In the Bunge and the Lopez-Bote studies dressing percentage included head-on while the PIC and University of Illinois data are with head-off. Figure 4. Energy Density and Yield 82 BUNGE DP (%) = 4.185*DE (Mcal/kg) R 2 = LOPEZ-BOTE DP (%) = 3.72*ME (Mcal/kg) PIC DP (%) = 7.00*ME (Mcal/kg) Dressing % IL - 5 POINTS DP (%) = 2.93*ME (Mcal/kg) R 2 =0.96 IL - 3 POINTS DP (%) = 3.68*ME (Mcal/kg) R 2 = Energy Density (Mcal ME/kg) PIC data yielded the highest slope of 7.00 (DP /(Mcal ME/kg)) while the slopes of the other three studies yielded between 3.68 and 4.19 (DP/(Mcal ME/kg)). Conservatively, 3.68 (DP/(Mcal ME/kg)) was chosen for the model. Since only two studies with heads-off were examined, the average intercept of these two studies will be used (i.e. 63.4%). Also note - if only the two highest energy density levels were analyzed (going from a typical corn/sbm diet to a high fat diet), the slope of the relationship almost doubles from our conservative estimate (PIC - 7.0, Univ IL and Bunge 5.0 DP/(Mcal/kg)). Dressing % = 3.68 x ME (Mcal/kg) For example, assuming a typical corn/sbm diet contains 3.3 Mcal ME/kg and a 5% added fat diet contains 3.5 Mcal ME/kg, then yield would be predicted to increase by 0.8%. On a 120 kg live weight pig that would yield 1.0 kg more carcass.

9 Predictions of FCR Assuming that a typical corn/sbm diet contains 3.3 Mcal ME/kg and this should be used as the standard when deciding on the energy level to formulate to, then an adjustment factor can be calculated to predict the expected change in FCR for a given energy level. This adjustment was made in order to incorporate FCR s of pigs during different weight periods. For example, if the energy density of the diet changes from 3.3 to 3.5 ME Mcal/kg, the equation in Figure 5 would yield 0.99 for a 3.3 Mcal/kg diet and for a 3.5 Mcal ME/kg diet. This means that one would expect a 6.5% improvement (i.e =6.5%) in FCR by formulating to the 3.5 Mcal ME/kg level. It is interesting to note that the PIC USA experimental pigs became fatter on the high energy diet. This is reflected in the FCR adjustment factor. If a regression line for FCR with ME was constructed using only the two points of this study, the slope of the adjustment factor would not be as steep (-0.25 rather than ). However, if the University of Illinois data for the two highest energy data points were used for the analysis, the slope would be steeper (-0.40). The pigs within the University if Illinois trial did not get fatter on the higher energy diet Figure 5. Energy and FCR 1.1 IL Spanish FCR Adj. Factor Adj Fact=-0.33*ME(Mcal/kg)+2.08 R 2 =0.98 PIC Bunge 0.95 Model ME (Mcal/kg) Carcass Quality In this simple model the assumption is that carcass quality does not change significantly, when increasing energy density, if the diet is balanced to the same concentration of lysine per Mcal of ME. In the University of Illinois study, 10 th rib backfat remained the same for the 3.3 and 3.5 Mcal ME/kg diets (21.8 to 21.6 mm, respectively). In the Spanish study, the pigs on the barley-no-fat diet measured 13.6 mm of last rib backfat while the pigs on the barley-fat diet measured 14.6 mm. During the PIC experiment, the pigs put on 3 mm more backfat on the high energy diet than they did for the lower energy diet. The Bunge pigs did not get fatter at P2 above 3.2 Mcal DE/kg. In only one of the four studies was the carcass

10 quality affected at the higher energy density. This aspect is important when it comes to economics and one should evaluate this under their own particular situation and carcass value packer matrix. Example calculation Table 10 contains the two diets to be compared. Each contains 2.6 grams of lysine per Mcal ME. Table 10. Example diets for economical comparison Ingredient Cost ($/kg) Hi Energy (%) Med Energy (%) Corn L-Lysine SBM 48% Fat Other Cost ($/kg) Calculated Nutrient Composition NCR ME (Mcal/kg) Lysine (%) g Lysine / Mcal ME The diets will be fed from kg of live body weight. FCR of the Medium Energy diet is assumed to be 3.08 for the given weight range. From the FCR adjustment equation, the predicted FCR from the high energy diet should be Therefore, feed cost for the high energy diet is calculated as $ 1.00/pig higher than for the corn/sbm diet. From the Dressing Percent Equation one should expect a 0.8% increase for the pigs on the high energy diet (i.e. 1 kg). If the carcass base price is $ 1.60/kg, then one would gross $ 1.60/pig. Therefore, the net return after feed cost would be $ 0.60/pig. This is a very conservative estimate of the actual savings. The 7% savings in feed delivery cost and feed mill wear were not included in this estimate. Also, the higher yield could elevate a producer to a higher yield class in a particular packer s grade and yield matrix which could be an additional few points of pork value. Heavier carcasses usually receive a premium when they move into the next yield class, if they meet the same quality standards. Quality of Energy Source PIC USA TD Technical Memo 153 (Boyd et al., 1997)is a good source of information when choosing energy sources. This report indicates that diet is a major determinant of body fat composition since the pig quantitatively transfers dietary fatty acids to fat depots. Saturated fatty acids have a positive influence on firmness and cohesiveness of fat, while monounsaturated and polyunsaturated fatty acids, in particular, have a negative influence (for references see Boyd et al., 1997). Pigs cannot synthesize polyunsaturated fatty acids, therefore, they are only deposited if they are included in the diet. Extensive use of unsaturated fat sources results in their deposition with the result being soft body fat and increased tendency for its oxidation and rancidity. PIC USA developed a curve that allows nutritionist to predict the impact of dietary fat (type and level) on body fat (see Figure 6).

11 Mean Body Fat IV NCor n Figure 6. Predicted Body Fat IV PIC USA, 1997 NCorn+Tallow 5% HOC(65) NCorn+AV 5% NCorn+CWG 5% NCorn+Veg 5% KEY: NCorn - Normal Corn IV=128 HOC(65) - High Oil Corn 65% replacement IV=128 Tallow - IV=47 CWG - Choice White Grease, IV=65 AV - Animal Vegetable Blend, IV=78 Veg - Vegetable Oil, IV= Dietary IV Product Conclusion The energy value of individual ingredients is not a good estimate of the economical value of these ingredients. To try and estimate the true value of energy in finishing swine diets, a simple model was developed. The model takes into account the effects of dietary energy on feed conversion and carcass yield. The issue of fat quality (particularly for export markets) in terms of backfat increase with the high energy diets is real but undefined and more work needs to be done in this area with various genotypes. The model is only presented as a demonstration tool in order to show how to evaluate energy density and profitability. The equations presented here were created using some recent data sets. On-farm-trials should be used to develop one s own equations under his/her conditions and genotypes to determine profitability. References Boyd, R.D. and M.E. Johnston Comparison of two dietary energy strategies for growth. PIC USA T&D Technical Report 48. PIC USA, Franklin, KY. Boyd, R.D., M.E. Johnston, K. Scheller, A.A. Sosnicki and E.R. Wilson Relationship between dietary fatty acid profile and body fat composition in growing pigs. PIC USA T&D Technical Report 153. PIC USA, Franklin, KY. Campbell, R.G The effect of dietary energy content on the performance and dressing percentage of female pigs offered feed ad libitum, from 65 to 105 kg. Internal research report, Bunge Australia, Corowa, N.S.W. Emmans, G.C Effective energy : a concept of energy utilization applied across species. British J. Nutr. 71: Johnston, L.J., J.E. Pettigrew and G.C. Shurson Energy systems and their value for use in swine diet formulation. Proc. 57 th Minnesota Nutrition Conference and Protiva Technical Symposium, pp

12 Lopez-Bote, et al., Effect of dietary lard on performance, fatty acid composition and susceptibility to lipid peroxidation in growing-finishing female and entire male pigs. Can. J. Anim. Sci. 77: Noblet, J The net energy system: application to US swine industry. Swine Summit Proceedings, Heartland Lysine, Inc. Stein, H.H., J.D. Hahn and R.A. Easter, Effects of decreasing dietary energy concentration in finishing pigs on carcass composition, Journal of Animal Science, 74 (Suppl. 1) : 65.