Published November 24, 2014
Effects of dietary lipid sources on performance and apparent total tract digestibility of lipids and energy when fed to nursery pigs1 S. M. Mendoza and E. van Heugten2 Department of Animal Science, North Carolina State University, Raleigh 27695
ABSTRACT: Acidulated fats and oils are by-products of the fat-refining industry. They contain high levels of FFA and are 10% to 20% less expensive than refined fats and oils. Two studies were designed to measure the effects of dietary lipid sources low or high in FFA on growth performance and apparent total tract digestibility (ATTD) of lipids and GE in nursery pigs. In Exp. 1, 189 pigs at 14 d postweaning (BW of 9.32 ± 0.11 kg) were used for 21 d with 9 replicate pens per treatment and 3 pigs per pen. Dietary treatments consisted of a control diet without added lipids and 6 diets with 6% inclusion of lipids. Four lipid sources were combined to create the dietary treatments with 2 levels of FFA (0.40% or 54.0%) and 3 degrees of fat saturation (iodine value [IV] = 77, 100, or 123) in a 2 × 3 factorial arrangement. Lipid sources were soybean oil (0.3% FFA and IV = 129.4), soybean-cottonseed acid oil blend (70.5% FFA and IV = 112.9), choice white grease (0.6% FFA and IV = 74.8), and choice white acid grease (56.0% FFA and IV = 79.0). Addition of lipid sources decreased ADFI (810 vs. 872 g/d; P = 0.018) and improved G:F (716 vs. 646 g/kg; P < 0.001). Diets high in FFA tended (P = 0.08) to improve final BW (21.35 vs. 21.01 kg) and ADG (576 vs. 560 g/d). Lipid-supplemented diets had greater ATTD of lipids than control diets (67.4% vs. 29.7%; P < 0.001).
Apparent total tract digestibility of lipids was greater in diets with low FFA (69.9% vs. 64.9%; P < 0.001) and decreased linearly with increasing IV (73.2%, 69.1%, and 67.2%). For GE, ATTD was greater in diets with low FFA (83.1% vs. 80.9%; P = 0.001). In Exp. 2, 252 pigs at 7 d postweaning (BW of 7.0 ± 0.2 kg) were used for 28 d with 9 replicate pens per treatment and 4 pigs per pen. Diets included a control diet without added lipids and 6 treatments with 2.5%, 5.0%, or 7.5% of lipids from either poultry fat (1.9% FFA) or acidulated poultry fat (37.8% FFA) in a 2 × 3 factorial arrangement. Addition of lipids increased (P < 0.001) final BW (19.9 vs. 18.4 kg) and ADG (460 vs. 405 g/d) regardless of source. Fat increased (P < 0.001) ADFI when added at 2.5% and then decreased ADFI with each further increment (663, 740, 681, and 653 g for 0%, 2.5%, 5.0%, and 7.5% fat, respectively). Inclusion of lipids linearly (P < 0.001) improved G:F (615, 615, 688, and 692 g/kg for 0%, 2.5%, 5.0%, and 7.5% fat, respectively) and ATTD of lipids (17.8%, 50.2%, 71.0%, and 77.3% for 0, 2.5, 5.0, and 7.5% fat, respectively) and GE (76.1%, 76.4%, 83.3%, and 84.4% for 0%, 2.5%, 5.0%, and 7.5% fat, respectively). Acidulated lipids resulted in similar performance compared with refined lipids and could be economical alternatives to more expensive lipid sources.
Key words: digestibility, free fatty acids, lipids, performance, pigs © 2013 American Society of Animal Science. All rights reserved. INTRODUCTION Acidulated fats and oils are by-products of the fatrefining industry. The purpose of refining is to remove 1Appreciation is expressed to the staff at the North Carolina State
University Swine Educational Unit for care of the animals and staff at the Feed Mill Educational Unit for assistance in feed preparation. Funded in part by the North Carolina Agricultural Foundation (Raleigh, NC). 2Corresponding author:
[email protected] Received March 17, 2013. Accepted December 5, 2013.
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J. Anim. Sci. 2014.92:627–636 doi:10.2527/jas2013-6488
nontriglyceride molecules. During the neutralization step, caustic soda is added to the crude oil and reacts with FFA, resulting in soap stock and fats and oils with low impurities. Soap stock is then acidulated by the addition of sulfuric acid, which again releases FFA, and this product is referred to as acidulated fat (Levin and Swearingen, 1953). Acidulated fats and oils are high in FFA content and are approximately 10% to 20% less expensive than refined fats and oils. Lipid composition and configuration can greatly influence intestinal lipid absorption by affecting
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micelle formation, especially chain length, position of fatty acids on the glycerol backbone, FFA content, and degree of saturation (Freeman, 1984). Commonly used indicators of the dietary energetic value of lipids in pigs are the presence of FFA and the degree of saturation of the fatty acids (NRC, 2012). Increasing FFA concentration in lipids causes a progressive reduction in their energy value (Wiseman et al., 1991; Powles et al., 1993; Jørgensen and Fernández, 2000). Fats of animal origin have a greater content of saturated fats and have lower digestibility and energy value than oils of vegetable origin (Cera et al., 1988a; Jørgensen et al., 1992; Øverland et al., 1994; Wiseman et al., 1990). The effects of FFA content of supplemental lipids on performance of pigs have not been extensively studied, and the experiments conducted have produced conflicting results (Bayley and Lewis, 1965; Frobish et al., 1970; Hillcoat and Annison, 1974; Swiss and Bayley, 1976). More recently, DeRouchey et al. (2004) reported no impact of FFA on pig performance, which indicates that fats with high FFA content, such as acidulated lipids, may be used in diets of nursery pigs without reducing performance. Thus, the objective of the present studies was to measure the dietary effect of FFA, saturation, and level of lipid inclusion on growth performance and ATTD of lipids and GE in nursery pigs. MATERIALS AND METHODS Animal use protocols were approved by the North Carolina State University Institutional Animal Care and Use Committee. Experiment 1 This experiment was conducted using 189 crossbred pigs ([Landrace × Yorkshire] × [Hampshire × Duroc]), with an average initial BW of 9.32 ± 0.11 kg. Pigs were weaned at approximately 21 d of age and fed a common diet (Renaissance Nutrition Inc., Roaring Spring, PA) for 14 d to adjust pigs to solid feed, followed by treatment diets for 21 d. Pigs were blocked by BW and sex and assigned to 1 of 7 dietary treatments. Litter mates were distributed across treatments and avoided in the same pen. Pigs were placed into a temperature-controlled raiseddeck nursery at the Swine Educational Unit (Raleigh, NC) and housed in 63 pens and 3 pigs per pen (0.91 × 1.52 m) with 9 replicate pens per treatment. Two farrowing groups, 2 wk apart, were used for this experiment to obtain sufficient numbers of pigs for this study. The first group represented blocks 1 to 4, and the second group represented blocks 5 to 9. Pigs were allowed ad libitum access to feed and water throughout the experiment. Each pen had 2 nipple water drinkers and a double-space feeder.
Feed was manufactured at the North Carolina State University Feed Mill Educational Unit. Two corn-soybean meal base mixes were formulated to meet or exceed all nutrient concentrations suggested by NRC (1998) and contained 3.76 g standardized ileal digestible Lys/ Mcal ME. The first base mix was divided into 6 portions, to which lipid sources were added to generate the final dietary treatments. The second base mix served as the negative control diet. The purpose of this process was to ensure that diets within lipid supplemented treatments were identical in composition. Additionally, diets contained 0.5% of titanium dioxide as indigestible marker to calculate apparent total tract digestibility (ATTD) of lipids and GE. Four sources of lipids (Divers Processing Co. Inc., Portsmouth, VA) were combined to create 6 diets in a 2 × 3 factorial arrangement with 2 levels of FFA (low or high FFA concentrations of 0.4% and 54.0% on an as-fed basis, respectively) and 3 degrees of lipid saturation (low, medium, or high with iodine values [IV] of 77, 100, and 123, respectively). Lipids were supplemented at 6%, and a negative control diet without added lipids was included in the design (Table 1). Lipid sources consisted of soybean oil (SO; 0.3% FFA and IV = 129.4), soybeancottonseed acid oil blend (SAO; 70.5% FFA and IV = 112.9), choice white grease (CWG; 0.6% FFA and IV = 74.8), and choice white acid grease (CWAG; 56.0% FFA and IV = 79.0; Table 2). The CWAG was obtained from the refining process of the original CWG that was used in the present study. Lipid sources were included in diets at the following proportions: diet 1, 100% CWG; diet 2, 95% CWAG and 5% CWG; diet 3, 50% SO and 50% CWG; diet 4, 38% SAO, 12% SO, 48% CWAG, and 2% CWG; diet 5, 100% SO; and diet 6, 76% SAO and 24% SO (Table 3). Diets were fed in meal form. Experiment 2 This experiment was conducted using 252 crossbred pigs ([Landrace × Yorkshire] × [Hampshire × Duroc]) with an average initial BW of 7.04 ± 0.20 kg. Pigs were weaned at approximately 21 d of age and fed a common diet (Renaissance Nutrition Inc.) for 7 d to allow pigs to adjust to solid feed. Piglets were used for 28 d in a growth performance study to determine the effects of source of lipids and level of inclusion of supplemental lipids on growth performance and ATTD of lipids and GE. Pigs were blocked by BW and sex and assigned to 1 of 7 dietary treatments in a 2 × 3 factorial arrangement plus a negative control. Litter mates were avoided in the same pen. Factors consisted of lipid source (Divers Processing Co. Inc.; poultry fat [PF]: 1.9% FFA and IV = 85.8 and acidulated poultry fat [APF]: 37.8% FFA and IV = 85.5) and lipid level (2.5%, 5.0%, and 7.5%). A negative control diet without supplemental lipids was
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Table 1. Composition of the experimental diets for Exp. 1 and Exp. 2, as-fed basis1 Exp. 12 Item Ingredient, % Corn, yellow dent Soybean meal, 47.5% CP Lipids l-Lys·HCl dl-Met l-Thr Monocalcium phosphate, 21% P Limestone Salt Copper sulfate, 25.2% Cu Vitamin premix4 Trace mineral premix5 Titanium dioxide6 Analyzed composition, % Ether extract Titanium dioxide 6
Exp. 23 2.5% Lipids 5.0% Lipids
0% Lipids
6% Lipids
0% Lipids
7.5% Lipids
65.31 30.23 0 0.37 0.14 0.14 1.55 1.09 0.4 0.08 0.04 0.15 0.5
55.02 34.5 6 0.38 0.18 0.15 1.53 1.07 0.4 0.08 0.04 0.15 0.5
66.56 29.34 0 0.35 0.12 0.12 1.35 0.99 0.4 0.08 0.04 0.15 0.5
62.47 30.90 2.5 0.36 0.14 0.13 1.35 0.98 0.4 0.08 0.04 0.15 0.5
58.44 32.41 5.0 0.37 0.16 0.14 1.34 0.97 0.4 0.08 0.04 0.15 0.5
53.97 34.35 7.5 0.38 0.18 0.15 1.34 0.96 0.4 0.08 0.04 0.15 0.5
2.68 0.40
7.27 0.51
2.78 0.42
4.87 0.46
6.94 0.50
9.61 0.43
1Diets
were formulated to meet or exceed NRC (1998) requirements. sources were soybean oil (0.3% FFA and iodine value [IV] = 129.4), soybean–cottonseed acid oil blend (70.5% FFA and IV = 112.9), choice white grease (0.6% FFA and IV = 74.8), and choice white acid grease (56.0% FFA and IV = 79.0) and were included in diets 1 to 6 in different ratios. 3Lipid sources were poultry fat and acidulated poultry fat. 4Supplied per kilogram of complete diet: 8,227 IU of vitamin A, 1,172 IU of vitamin D as D-activated animal sterol, 47.0 IU of vitamin E, 0.03 mg of vitamin 3 B12, 5.8 mg of riboflavin, 35.2 mg of niacin, 23.5 mg of d-pantothenic acid as calcium pantothenate, 3.8 mg of vitamin K as menadione dimethylpyrimidinol bisulfate, 1.7 mg of folic acid, and 0.23 mg of d-biotin. 5Supplied per kilogram of complete diet: 16.5 mg Cu as CuSO , 0.30 mg I as ethylenediamine dihydriodide, 165 mg Fe as FeSO , 40 mg Mn as MnSO , 0.30 4 4 4 mg Se as Na2SeO3, and 165 mg Zn as ZnO. 6Titanium dioxide was used as an indigestible maker. 2Lipid
Table 2. Chemical composition of experimental lipid sources, as-fed basis Exp. 1 Item Moisture,2 % Insoluble impurities,3 % Unsaponifiable matter,4 % Free fatty acids,5 % Iodine value6 Anisidine value7 Peroxide value, mEq/kg Initial8 4 h AOM9 24 h AOM9 1Choice
Soy oil 0.4 0 0.54 0.3 112.9 12.4
Soy acid oil 0.6 0 2.6 70.5 129.4 5.8
CWG1 0.2 0 0.37 0.6 74.8 0
CWG acid 10.4 0.26 1.8 56.0 79.0 15.3
Poultry fat 0.4 0 1.3 1.9 85.8 0
33.6 103.6 543.0
1.8 1.0 2.0
1.8 2.6 6.6
7.0 4.0 1.4
0.1 0.1 0.1
white grease. Ca2a-45 (AOCS, 2009). 3Method Ca3a-46 (AOCS, 2011a). 4Method 933.08 (AOAC, 1933). 5Method 940.28 (AOAC, 1940). 6Method 920.159 (AOAC, 1920). 7Method Cd18-90 (AOCS, 2011b). 8Method 969.33 (AOAC, 1969). 9AOM, active oxygen method (IUPAC, 1979). 2Method
Exp. 2 Acidulated poultry fat 1.2 0 2.2 37.8 85.5 10.1 0.1 0.1 0.4
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Table 3. Percentage contribution of experimental lipid sources to supplemental lipids for the dietary treatments, Exp. 11 Treatment FFA,% 1 0.6 2 54 3 0.4 4 54 5 0.3 6 54
IV 74.8 78.8 102.1 97.8 129.4 116.8
Soy oil — — 50 12 100 24
Percentage of inclusion Soy acid oil CWG2 CWG acid — 100 — — 5 95 — 50 – 38 2 48 — — — — — 76
1Lipid sources were combined to create 6 diets in a 2 × 3 factorial arrangement with 2 levels of FFA (low or high) and 3 degrees of lipid saturation (low, medium, or high iodine value [IV]). 2Choice white grease.
included in the experimental design. Pigs were placed at the Swine Educational Unit (Raleigh, NC) at 4 pigs per pen using a total of 63 pens with 9 replicate pens per treatment. Two farrowing groups, 2 wk apart, were used for this experiment. The first group represented blocks 1 to 5, and the second group represented blocks 6 to 9. Feed was manufactured at the North Carolina State University Feed Mill Educational Unit. Four corn-soybean meal base mixes were formulated to meet or exceed all nutrient concentrations suggested by NRC (1998) and contained 3.65 g standardized ileal digestible (SID) Lys/ Mcal ME (Table 1). Thus, these base mixes were formulated with increasing amounts of soybean meal and synthetic AA as levels of supplemental lipids increased (0%, 2.5%, 5.0%, and 7.5%) to maintain a constant SID Lys/ Mcal ME ratio between diets. The first base mix served as the negative control diet without added lipids. Base mix 2 was divided into 2 equal portions, and PF was added to 1 portion at 2.5%, whereas APF was added to the second portion at 2.5%. The same procedure was repeated for the 5.0% and 7.5% lipid inclusion rates. This procedure of diet manufacturing ensured diets were close to identical within lipid level. All dietary treatments contained 0.5% of titanium dioxide as an indigestible marker to calculate ATTD of lipids and GE, and diets were fed in meal form. Measurements In each experiment, pig BW and feed disappearance were measured weekly. Feed disappearance was calculated from the feed offered minus feed refusal. At the end of the study, fresh fecal samples were collected from at least 2 pigs per pen after defecation during 3 consecutive days and frozen in plastic bags at -20°C for subsequent analyses. Feed and fecal samples were prepared for analyses by drying for 4 d at 55°C. Feed was ground using a ThomasWiley laboratory mill (Thomas Scientific, Swedesboro, NJ) through a 1-mm mesh screen, and the fecal samples
were ground using a kitchen blender (Oster, Sunbeam Products Inc., Jarden Corporation, New York, NY). Chemical Analyses Lipid sources were analyzed by a commercial laboratory (New Jersey Feed Laboratory Inc., Trenton, NJ) for moisture (AOCS, 2009), insoluble impurities (AOCS, 2011a), unsaponifiable matter (AOAC,1933), FFA content (AOAC, 1940), IV (AOAC, 1920), anisidine value (AOCS, 2011b), initial peroxide value (AOAC, 1969), and 4 and 20 h peroxide value by the active oxygen method (AOM; IUPAC, 1979). Concentrations of titanium dioxide in the diets and in the fecal samples were determined according to Myers et al. (2004) with a minor modification. The modification consisted of the addition of 50 μL of stabilized 30% hydrogen peroxide into all wells of the microwell plate 30 min before reading to ensure the orange color of the reaction. Concentrations were determined relative to a standard curve at 410 nm using a microplate reader (Synergy HT Multi-detection; Bio-Teck Instruments Inc., Winooski, VT). Lipid content of feed and fecal samples were measured by ether extraction after acid hydrolysis with HCl (AOCS, 2004) using an XT15 fat extractor and HCl hydrolysis system (ANKOM Technology, Macedon, NY). The gross energy of diets and feces was determined by dynamic bomb calorimetry (C5000 Calorimetric System, IKA, Wilmington, NC), calibrated using benzoic acid. Apparent total tract digestibility of lipids and GE was calculated using the index ratio procedure (Adeola, 2001) as follows: Marker in diet × Nutrient in feces Digestibility = 100 − 100 × . Marker in feces × Nutrient in diet
Statistical Analyses For both experiments statistical analysis was performed using the GLM procedure of SAS (SAS Inst. Inc., Cary, NC) with the pen as the experimental unit. In Exp. 1, the model included block (BW), FFA content, IV, and the FFA × IV interaction. Initial BW was used as a covariate, given that it differed between treatments. Orthogonal contrast comparisons were conducted to determine linear and quadratic effects of IV and to compare the negative control with lipid-added diets. In Exp. 2, the model included block (BW), source, lipid level, and the source × lipid level interaction. Orthogonal contrasts were used to determine linear and quadratic effects of lipid level and to compare the negative control with lipid-added diets. For Exp. 2, a second model was included to determine if there was an interaction between farrowing group and
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Table 4. Effects of FFA concentration and iodine value (IV) of supplemental lipids (6%) on growth performance and apparent total tract digestibility of lipids and GE in nursery pigs in Exp. 11 No lipid Item control 74.8 BW, kg Initial 9.33 9.30 d 73 12.36 12.64 d 14 16.23 16.73 d 21 21.01 21.45 ADG, kg d 0 to 73 0.439 0.479 d 8 to 14 0.554 0.584 d 15 to 21 0.697 0.689 d 0 to 21 0.560 0.581 ADFI, kg (as-fed basis) d 0 to 7 0.667 0.628 d 8 to 14 0.867 0.797 d 15 to 214,5 1.082 1.020 d 0 to 21 0.872 0.815 G:F d 0 to 7 0.660 0.765 0.638 0.736 d 8 to 144,6 d 15 to 21 0.645 0.675 d 0 to 21 0.646 0.716 Apparent total tract digestibility,% Lipids6,7 29.7 73.2 GE 81.7 83.2
0.4% FFA IV 102.1
78.8
54% FFA IV 97.8
129.4
116.8
SEM
Fat2
P-value IV
FFA
9.30 12.44 16.34 21.07
9.26 12.39 16.41 20.62
9.34 12.94 16.99 21.35
9.34 12.59 16.90 21.91
9.34 12.46 16.87 21.69
0.03 0.18 0.28 0.40
— 0.239 0.122 0.363
— 0.144 0.684 0.678
— 0.279 0.104 0.079
0.451 0.557 0.695 0.563
0.443 0.575 0.646 0.541
0.522 0.578 0.639 0.576
0.473 0.616 0.731 0.603
0.454 0.629 0.704 0.592
0.026 0.030 0.029 0.019
0.239 0.313 0.798 0.363
0.144 0.792 0.206 0.678
0.279 0.218 0.485 0.079
0.593 0.784 1.033 0.803
0.616 0.779 0.909 0.768
0.636 0.848 0.955 0.813
0.610 0.845 1.090 0.849
0.600 0.803 1.042 0.815
0.024 0.032 0.040 0.025
0.044 0.081 0.085 0.018
0.402 0.640 0.101 0.368
0.925 0.147 0.215 0.159
0.757 0.713 0.671 0.706
0.728 0.735 0.688 0.715
0.821 0.685 0.665 0.711
0.777 0.728 0.672 0.715
0.755 0.785 0.678 0.732
0.033 0.020 0.019 0.011
0.003
