Published December 8, 2014
Growth performance and carcass characteristics of pigs fed short-season corn hybrids1 F. O. Opapeju,* C. M. Nyachoti,*2 J. D. House,*† H. Weiler,† and H. D. Sapirstein‡ Departments of *Animal Science, †Human Nutritional Sciences, and ‡Food Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
ABSTRACT: An experiment was conducted to determine growth performance, carcass characteristics, and fat quality of growing-finishing pigs fed diets based on short-season corn hybrids. Twenty-four individually housed, Cotswold, growing pigs with an initial BW of 41.4 (SD = 1.4) kg were blocked by BW and sex and randomly allotted from within block to 1 of 3 diets to give 8 replicate pigs per diet. Experimental diets consisted of a control based on barley and 2 diets based on corn as the main energy sources. A 3-phase feeding program for 20 to 50 kg (phase I), 50 to 80 kg (phase II), and 80 to 110 kg (phase III) of BW was used. Diets for each phase contained approximately 3.5 Mcal/kg of DE, with total lysine of 0.95, 0.75, and 0.64% in phase I, II, and III diets, respectively. Average daily gain,
ADFI, and G:F were monitored weekly during each phase. Pigs were slaughtered after reaching a minimum BW of 100 kg to determine carcass characteristics. There were no effects of diet on ADG, ADFI, and G:F (0.45 ± 0.02, 0.34 ± 0.02, and 0.31 ± 0.02 for phase I, II, and III, respectively). Carcass length, dressing percent, LM area, loin depth, backfat thickness, belly firmness, and L*, b*, and a* fat color were not different across dietary treatments. Pigs fed one corn variety had no differences in fatty acid profile with barley-fed pigs, whereas those fed the other variety of corn had a greater (P < 0.05) concentration of PUFA in their backfat. The results indicate that growth performance, carcass characteristics, and fat quality of pigs fed diets based on short-season corn hybrids and those fed the barleybased diet were not different.
Key words: carcass quality, corn, growth performance, pig ©2006 American Society of Animal Science. All rights reserved.
INTRODUCTION Traditionally, corn production in Manitoba, Canada, has been low because of the climate; however, it has increased recently due to the development of high yielding, low-corn heat units (CHU) rated hybrids by plant breeders. In areas with low temperatures, such as Manitoba, the heat available to support corn growth is measured by CHU, a quantitative assessment of the useful heat available for the growth and development of corn (MAFRI, 2004). Because of the increase in corn production, the amount of locally grown corn that is available for use in making swine feed has increased. However, pigs fed corn-based diets could produce inferior quality products
1
We appreciate Manitoba Corn Growers Association and Manitoba Pork Council for financial support. Special thanks to G. H. Crow and L. Onischuk for helping with statistical analysis. 2 Corresponding author:
[email protected] Received July 3, 2005. Accepted June 1, 2006.
J. Anim. Sci. 2006. 84:2779–2786 doi:10.2527/jas.2005-353
for some markets compared with pigs fed barley- or wheat-based diets in terms of meat and fat color because yellow corn contains higher amounts of carotenoids, naturally occurring fat soluble pigments often found in plants (NRC, 1998; Prache et al., 2003; Carr et al., 2005). Another product quality concern related to feeding corn-based diets to pigs is the production of soft fats due to the high content of unsaturated fatty acids (UFA) in corn. A high amount of UFA in pork has been associated with increased difficulties in belly slicing and such quality problem as susceptibility to rapid oxidative rancidity (Averette Gatlin et al., 2002). According to Carr et al. (2005), pigs fed a corn-based diet had higher G:F than those fed a barley-based diet but similar carcass characteristics. However, Robertson et al. (1999) reported that pigs fed corn-based diets had darker LM compared with those fed diets based on hulless barley. Thus, the effects of feeding corn vs. barley to swine on growth performance and carcass characteristics have not been conclusively determined. Therefore, the objective of this study was to evaluate the effects of representative Manitoba-grown corn hy-
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brids on growth performance and carcass characteristics of growing-finishing pigs using a barley-based diet as control.
to allow unrestricted access to feed and water at all times. The diets were provided in mash form. Individual pig BW and feed disappearance were monitored weekly during each phase to determine ADG, ADFI, and G:F.
MATERIALS AND METHODS Carcass Evaluation Animals and Diets The use of pigs and the experimental procedures were reviewed and approved by the Animal Care Committee of the University of Manitoba, and animals were cared for according to the standard guidelines of the Canadian Council on Animal Care (CCAC, 1993). Twenty-four Cotswold pigs (12 barrows and 12 gilts) with an average initial BW of 41.4 (SD = 1.4) kg were obtained from the University of Manitoba’s Glenlea Swine Research Farm for use in this study. Pigs were blocked on the basis of BW and sex into 8 blocks (4 blocks each of barrows and gilts) each with 3 pigs. Pigs from each block were randomly allotted to 1 of 3 treatment groups, resulting in a total of 8 pigs per treatment. The 3 dietary treatments consisted of a barley-based diet (control) and 2 diets each based on 1 of the 2 most cultivated corn hybrids in Manitoba, 39M27 (Pioneer Hi-Bred Ltd, Chatham, ON; corn 1) and 39W54 (Pioneer Hi-Bred Ltd, Chatham, ON; corn 2). The barley sample is a 6-row barley hybrid and the corn hybrids are early maturing hybrids requiring less than 2,400 CHU, an equivalent of less than 75 d, to reach maturity (Dwyer et al., 1991). The CHU rating of corn 1 and corn 2 were 2,150 and 2,100, respectively. Corn 1 is a genetically modified corn that is resistant to European corn borer. It contains a protein (Cry 3Bbl) from a bacterium, Bacillus thuringiensis, that is toxic to European corn borer and thus could potentially minimize the use of insecticides (MAFRI, 2004; Hyun et al., 2005). All grain samples were from the 2003 planting season harvest. The 2 corn samples were obtained from Carman, Manitoba, whereas the barley sample was obtained from the University of Manitoba Glenlea Research Station. The 2 locations were within 100 km of Winnipeg (49° 53′ N, 97° 10′ W), Canada. The pigs were fed on a 3-phase dietary program for BW 20 to 50 kg (phase I), 50 to 80 kg (phase II), and 80 to 110 kg (phase III). Diets for each phase were formulated to meet the NRC (1998) nutrient standards for mixed sexes, with a high to medium lean growth rate (Table 1). The analyzed lysine (0.26 and 0.24% for corn 1 and corn 2, respectively) and other AA contents of the corn samples were similar to NRC (1998) values (Opapeju, 2005). Hence, the diets were formulated using NRC (1998) values based on the total lysine content of the ingredients, and the calculated dietary levels of CP, total lysine, and DE were similar across dietary treatments within each phase. Pigs were housed individually in 1.83 × 1.22-m floor pens with plastic-covered, expanded metal, sheet flooring in a temperature controlled room (19 to 21°C). Each pen was equipped with a feeder and a nipple drinker
On reaching an average live BW of 107.8 (SD = 2.9) kg, pigs were slaughtered after 18 h of feed deprivation. Before slaughter, pigs were weighed and then given an intramuscular injection of acepromazine maleate (0.3 mg/kg of BW; Atravet 10 mg injectable, Wyeth Animal Health, Ontario, Canada) mixed in a single syringe with 15 mg of ketamine hydrochloride/kg of BW (Ketalean, Bimeda-MTC Animal Health Inc., Ontario, Canada) as a preanesthetic tranquilizer. Once tranquilized sufficiently, approximately 20 mg of sodium pentobarbital/ kg of BW (Bimeda-MTC Animal Health Inc.) was administered intravenously through the lateral ear vein to provide for a plane of surgical anesthesia but not enough to cause respiratory arrest. Pigs were then exsanguinated, and the viscera were removed. The dressing percent was determined as the ratio of HCW (headon) to live BW at slaughter. The carcasses (head-on) were then split in 2 by cutting through the backbone and stored in a cooler at 4°C. After 24 h in the cooler, carcass length was measured on the right half of the carcass as the distance between the cranial face of the first rib and the tip of the aitch bone. The belly was fabricated from the right half of the carcass according to the UN/ECE standard procedure for porcine carcasses and cuts (ECE, 1997). Approximately 36 × 48 cm of the belly was removed and subjected to the belly flex test described by Rentfrow et al. (2003). Briefly, the carcass was centered on a polyvinyl chloride pipe (9-cm diam.) mounted perpendicularly on a board marked with a 2.54-cm grid matrix with the skin side down and the chine side against the board. Lateral and vertical flexes were calculated as the average of the lateral and vertical left and right flexes determined relative to the grid matrix on the left and right side of the board, respectively. About 50 g of leaf fat was removed for belly fat fatty acid analysis. The left half of the carcass was evaluated for backfat thickness, loin depth, and LM area (LMA). Midline backfat thickness was measured perpendicular to the skin at the first and last rib and at the last lumbar vertebra. The carcass was cut using the Hobart meatcutting machine (The Hobart Mfg. Co., Ltd., Toronto, Canada) between the 10th and 11th ribs to determine the 10th rib fat thickness, LM depth, and LMA. The outline of the LM was traced on acetate paper, and the LMA was later determined using a 0.25-cm2 grid. Samples of subcutaneous fat were obtained from each pig at the 10th and 11th ribs for backfat fatty acid and fat color analysis, respectively. The samples, about 50 g for fatty acid analysis and approximately 8 × 10 cm for fat color analysis, were carefully separated from the attached muscle. All fat samples were rinsed with
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Table 1. Ingredient composition (as-fed basis) and calculated nutrient composition of the experimental diets Phase I Item Ingredient, % Corn Barley Soybean meal, 48% CP Canola meal Dicalcium phosphate Limestone Mineral premix1 Vitamin premix2 L-LysineⴢHCl Sodium chloride Calculated composition3 CP, % Lysine, % Ca, % P, % Ca:P DE, Mcal/kg
Phase II
Phase III
Barley
Corn 1
Corn 2
Barley
Corn 1
Corn 2
Barley
Corn 1
Corn 2
— 78.26 11.20 7.73 0.06 1.18 0.50 0.50 0.17 0.40
72.00 — 15.30 9.91 0.12 1.17 0.50 0.50 0.10 0.40
72.00 — 15.30 9.91 0.12 1.17 0.50 0.50 0.10 0.40
— 83.85 4.98 8.70 0.02 0.98 0.50 0.50 0.12 0.35
77.17 — 7.90 12.53 0.06 0.94 0.50 0.50 0.05 0.35
77.17 — 7.90 12.53 0.06 0.94 0.50 0.50 0.05 0.35
— 89.71 3.89 4.00 0.01 0.93 0.50 0.50 0.11 0.35
79.75 — 5.00 13.00 0.01 0.88 0.50 0.50 0.01 0.35
79.75 — 5.00 13.00 0.01 0.88 0.50 0.50 0.01 0.35
17.55 0.95 0.59 0.49 1.20 3.46
17.49 0.95 0.60 0.50 1.20 3.54
17.79 0.95 0.60 0.50 1.20 3.55
15.62 0.75 0.50 0.45 1.11 3.46
15.39 0.75 0.50 0.45 1.11 3.54
15.70 0.75 0.50 0.45 1.11 3.55
14.14 0.63 0.45 0.40 1.12 3.49
14.42 0.64 0.46 0.41 1.12 3.54
14.74 0.64 0.46 0.41 1.12 3.55
1 Supplied the following per kilogram of complete diet: 15 mg of Cu as copper sulfate, 0.21 mg of I as calcium iodate, 100 mg of Fe as iron sulfate (monohydrate), 40 mg of Mn as manganese oxide, 0.30 mg of Se as sodium selenite, 150 mg of Zn as zinc oxide for phase 1 diets; and 15 mg of Cu as copper sulfate, 0.21 mg of I as calcium iodate, 100 mg of Fe as iron sulfate (monohydrate), 20 mg of Mn as manganese oxide, 0.15 mg of Se as sodium selenite, and 100 mg of Zn as zinc oxide for phase 2 and 3 diets. 2 Supplied the following per kilogram of complete diet: 8,250 IU of vitamin A, 825 IU of vitamin D3, 40 IU of vitamin E, 4 mg of vitamin K3, 5 mg of riboflavin, 35 mg of niacin, 25 g of vitamin B12, and 200 g of biotin for phase 1, 2 and 3 diets. 3 Calculated based on NRC (1998) feed composition data, except CP, which was based on analyzed values of barley, corn 1, and corn 2.
saline solution (0.9%) and stored at −80°C until further analysis. Fat color was evaluated according to the Commission International de l’Eclairage (CIE) L* (lightness), a* (red-green scale), and b* (yellow-blue scale) values (CIE, 1976) using a Minolta Spectrophotometer CM3500d (Minolta Co., Ltd., Osaka, Japan). The spectrophotometer was calibrated using the manufacturer’s zero calibration and white, standard, calibration caps. The L* scale ranged from 0 to 100%; that is, the greater the value, the lighter the color; the a* scale ranged from negative (green) to positive (red); and the b* scale ranged from negative (blue) to positive (yellow). Each sample was read thrice.
Fatty Acid Analysis Feed ingredient samples (corn and barley) and belly fat and backfat samples were analyzed for fatty acids. A representative sample of each grain ground through a 1-mm screen and thoroughly mixed was subjected to lipid extraction according to AOAC (1990) procedures. Extracted oil was methylated following the procedure of Folch et al. (1957). Belly fat and backfat samples were extracted and methylated according to the procedures of Folch et al. (1957). Fatty acid methyl esters were analyzed using a Hewlett-Packard 5890A gas chromatograph equipped with an autosampling injection system HP 7673 (Hewlett-
Packard Inc., Avondale, AZ). The 100-m-long column, an Agilent HP-88 capillary column (J and W Scientific, Folsom, CA), was made of fused silica coated with 88% cyanopropyl aryl siloxane (0.25-mm i.d. and 0.2-m film thickness). The column temperature began at 50°C, and after 1 min, it increased at a rate of 20°C/min to 160°C and was held at this level for 23 min. The temperature then increased at a rate of 2°C/min to 210°C and was held there for 7 min. To clean the column between samples, the column temperature was increased at a rate of 20°C/min to 240°C and was held at this level for 5 min. The flame ionization detector temperature was kept constant at 300°C. The fatty acid methyl esters were identified using a methyl ester standard GLC-461 (Nu Check Prep Inc., Elysian, MN).
Statistical Analysis All data were subjected to ANOVA with a randomized complete block design using the GLM procedures of SAS (SAS Inst. Inc., Cary, NC). The effects of sex (df = 1), block within sex (df = 6), and dietary treatment (df = 2) were included in the model as sources of variation. The individual pig was considered as the experimental unit. When a significant F-value (P < 0.05) was indicated by the ANOVA, dietary treatment means were separated and compared using Tukey’s test.
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Table 2. Fatty acid profiles (% of total) in barley and the corn cultivars used in the experimental diets1,2
Table 3. Fat content (%) and fatty acid profile (% of the diet) of phase III diets1
Corn Fatty acid
Barley
Capric, 10:0 Myristic, 14:0 Palmitic, 16:0 Palmitoleic, 16:1 Stearic, 18:0 Oleic, 18:1 Linoleic, 18:2 Linolenic, 18:3 Arachidic, 20:0 SFA3 MUFA PUFA UFA4
0.16 0.28 17.19 0.19 1.57 14.35 57.02 0.35 5.64 25.33 15.55 59.17 74.72
± ± ± ± ± ± ± ± ± ± ± ± ±
0.00 0.00 0.12 0.03 0.11 0.20 0.12 0.00 0.13 0.18 0.28 0.06 0.22
Corn 1 0.16 0.05 10.32 0.13 1.77 30.24 54.61 0.48 1.26 13.96 30.62 55.49 86.11
± ± ± ± ± ± ± ± ± ± ± ± ±
0.02 0.01 0.08 0.02 0.04 0.04 0.20 0.03 0.01 0.15 0.06 0.24 0.18
Corn Corn 2
0.13 0.06 11.44 0.13 2.00 25.67 57.73 0.50 1.39 15.38 26.08 58.63 84.71
± ± ± ± ± ± ± ± ± ± ± ± ±
0.01 0.02 0.21 0.02 0.10 0.16 0.29 0.02 0.01 0.36 0.12 0.24 0.36
Mean ± SD of each grain sample measured in duplicate. Only those fatty acids with value equal to or in excess of 0.05% of the total fatty acid content are listed. 3 Total SFA. 4 Total unsaturated fatty acids. 1 2
RESULTS AND DISCUSSION The fatty acid profile of barley and the 2 corn hybrids is presented in Table 2. Barley had a higher amount of SFA compared with the 2 corn hybrids, with the amount of myristic acid (14:0), palmitic acid (16:0), and arachidic acid (20:0) in barley being at least 367, 50, and 306%, respectively, higher than in the 2 corn hybrids. However, the 2 corn hybrids had higher amounts of oleic acid (18:1) compared with barley. This observation is consistent with previous research showing that corn has a higher amount of UFA compared with barley (NRC, 1998; Carr et al., 2005). The fatty acid profiles of the 2 corn hybrids varied (Table 2), which further confirms reports of variability in the chemical and nutrient composition of corn or corn products (Sproule et al., 1988; Adeola and Bajjalieh, 1997; Moeser et al., 2002). The fatty acid profiles of the corn hybrids evaluated in the current study were similar to the values reported by Rentfrow et al. (2003). Compared with the report of Carr et al. (2005), corn and barley samples evaluated in this study were at least 39, 65, and 123% lower in palmitic acid (16:0), palmitoleic acid (16:1), and stearic acid (18:0) concentration but about 20% higher in linoleic acid (18:2) concentration. In the barley and corn samples evaluated in the current study, palmitic acid and linoleic acid constituted the highest proportion of SFA and UFA, respectively (Table 2), and this observation is consistent with the reports of Rentfrow et al. (2003) and Carr et al. (2005). The evaluated cereals contributed the bulk of dietary fat representing 86, 83, and 84% of diet based on barley, corn 1, and corn 2, respectively (Table 3). The pattern observed for dietary fatty acid profile (Table 3) was similar to that of the cereal component of the diet (Table 2). For example, barley-based diet had more myristic and arachidic acid
Item, % Fat, % of the diet Fat, % supplied by the cereal Fatty acid Capric, 10:0 Myristic, 14:0 Palmitic, 16:0 Palmitoleic, 16:1 Stearic, 18:0 Oleic, 18:1 Linoleic, 18:2 Linolenic, 18:3 Arachidic, 20:0 SFA2 MUFA PUFA UFA3
Barley
Corn 1
Corn 2
1.87 1.61
3.56 2.95
3.80 3.19
0.00 0.13 0.29 0.00 0.03 0.34 1.01 0.03 0.09 0.44 0.36 1.06 1.42
0.00 0.00 0.32 0.00 0.07 1.17 1.76 0.07 0.04 0.46 1.20 1.84 3.04
0.00 0.00 0.38 0.00 0.08 1.11 2.01 0.07 0.05 0.55 1.14 2.10 3.23
1 Calculated based on the analyzed fat content and fatty acid profile of barley and corn samples and the USDA nutrient database values of fat content and fatty acid profiles of canola and soybean meals. 2 Total SFA. 3 Total unsaturated fatty acids.
but less stearic and oleic acid compared with corn-based diets just as observed in the cereals. A pig was lost during the experiment due to a nontreatment-related event. In the current study, sex results are presented only for the response criteria where the sex effect was significant because sex was only used for blocking and not as a primary question of the study. As a result, the experimental diets were formulated to meet the nutrient requirement for specific phases of pig’s growth and not for the differing nutrient requirements of the sexes. The effects of sex, where observed, were consistent with other studies. Interactions between diets and sex were not observed other than random occurrence with no biological implications.
Growth Performance and Carcass Characteristics The effects of dietary treatment on ADG, ADFI, and G:F are presented in Table 4. There were no differences in ADG, ADFI, and G:F of pigs fed the barley-based diets compared with those fed diets based on either of the 2 corn hybrids during any phase of the study or overall. Similarly, Carr et al. (2005) did not detect any differences in ADG, ADFI, and G:F between pigs (45 to 80 kg of BW) fed a barley-based diet and those fed a corn-based diet. Carcass characteristics of pigs fed barley- and cornbased diets are shown in Table 5. There were no differences in dressing percent, carcass length, backfat thickness, loin depth, and LMA among dietary treatments, which is consistent with the findings of Carr et al. (2005) showing no differences in the carcass and fat characteristics of pigs fed corn- and barley-based diets. Likewise, as in this study, Hyun et al. (2004, 2005) did not find
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Table 4. Effects of diet (barley vs. corn) on growth performance of growing-finishing pigs1 Corn Item 2
No. Initial BW, kg Final BW, kg Phase I, 38 to 50 kg ADG, kg ADFI, kg G:F Phase II, 50 to 80 kg ADG, kg ADFI, kg G:F Phase III, 80 to 110 kg ADG, kg ADFI, kg G:F Overall, 38 to 110 kg ADG, kg ADFI, kg G:F
Barley
Corn 1
Corn 2
SEM
P-value
7 40.7 107.9
8 41.5 107.3
8 42.0 108.1
0.381 1.192
0.100 0.854
0.84 1.90 0.44
0.86 2.03 0.43
0.92 1.95 0.49
0.044 0.069 0.023
0.464 0.483 0.163
0.86 2.40 0.33
0.80 2.42 0.33
0.89 2.56 0.35
0.048 0.079 0.020
0.395 0.320 0.820
0.84 2.75 0.30
0.89 2.80 0.31
0.97 3.02 0.31
0.049 0.087 0.017
0.227 0.117 0.895
0.85 2.35 0.36
0.85 2.41 0.36
0.93 2.51 0.39
0.029 0.065 0.012
0.117 0.272 0.287
1
Values are least squares means. Number of replicate pens per diet. Pigs were housed 1 per pen.
2
any differences in the carcass characteristics of pigs that were fed diets based on different hybrids of corn. The belly firmness as measured with the belly flex test was not affected by dietary treatment (Table 5). The values observed for the belly flex test for pigs that received corn 1 and 2 were similar to the values, 18 and 13 cm for vertical and lateral flex, respectively, reported by Rentfrow et al. (2003) for a similar size of belly for pigs fed conventional corn-based diets. The belly flex of pigs fed the barley-based diet was similar to that of pigs fed the corn-based diets, although this
could not be compared with previous research because this approach has not previously been used to measure belly firmness in pigs fed barley-based diets. There was no effect of dietary treatment on the L*, a*, and b* fat color (Table 5). Similar to the result of the current study, Carr et al. (2005) did not find any differences in L*, a*, and b* fat color of pigs fed the diet based on barley compared with those fed the cornbased diet. Corn has higher amount of pigments compared with barley (NRC, 1998), and this could contribute to the deposition of color fat (Carr et al. 2005). Although we did not measure carotenoid concentration of the grain samples used in the current study, differences in the concentration of pigments between corn and barley, if there were any, did not affect pork fat color.
Fatty Acid Profiles of the Backfat and Belly Fat The effects of dietary treatment on the profile of fatty acid in backfat are presented in Table 6. The backfat of pigs on the barley-based diet tended to have higher concentration of pentadecanoic acid (15:0; P = 0.092), palmitoleic acid (16:1; P = 0.080), and heptadecanoic acid (17:0; P = 0.089) compared with those fed the diet based on corn 2. Pigs on the barley-based diet had a higher (P < 0.05) concentration of heptadecenoic acid (17:1; P = 0.006) in their backfat compared with those that received diets based on corn. The concentration of eicosenoic acid (20:1) in the backfat of pigs fed diets based on barley and corn 1 was higher (P < 0.05) compared with those fed diet based on corn 2. The backfat of pigs fed the diet based on corn 2 had higher (P < 0.05) concentrations of linoleic acid (18:2) and PUFA compared with pigs fed the diet based on barley. Linoleic acid (18:2) is the only PUFA that was significantly (P = 0.038) affected by dietary treatment, and it is prob-
Table 5. Effects of diet (barley vs. corn) on carcass characteristics of growing-finishing pigs1 Corn Item 2
No. Dressing percent Carcass length, cm Midline backfat First rib, cm Last rib, cm Last lumbar, cm 10th rib fat, cm Loin depth, cm Longissimus muscle area, cm2 Vertical belly flex, cm Lateral belly flex, cm Back fat color3 L* a* b* 1
Barley
Corn 1
Corn 2
SEM
P-value
7 81.8 81.6
8 84.3 82.4
8 83.0 82.0
0.869 0.973
0.193 0.862
3.1 2.5 2.1 2.0 6.8 49.4 15.6 14.4
3.3 2.3 1.9 2.0 6.5 48.5 17.1 14.4
3.2 2.6 2.0 1.9 6.1 45.4 16.1 14.1
0.150 0.186 0.225 0.154 0.309 1.922 1.244 1.582
0.761 0.489 0.865 0.804 0.376 0.286 0.750 0.987
82.0 11.3 1.9
81.8 11.5 1.5
82.0 12.0 1.7
0.466 0.310 0.234
0.958 0.423 0.296
Values are least squares means. Number of replicate pens per diet. Pigs were housed 1 per pen. L* = lightness; a* = redness; and b* = yellowness.
2 3
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Table 6. Effect of diet (barley vs. corn) on backfat fatty acid profiles (% of total) in finishing pigs1,2 Corn Fatty acid 3
No. Capric, 10:0 Lauric, 12:0 Myristic, 14:0 Pentadecanoic, 15:0 Palmitic, 16:0 Palmitelaidoic, 16:1t Palmitoleic 16:1 Heptadecanoic, 17:0 Heptadecenoic, 17:1 Stearic, 18:0 Oleic, 18:1 Linoleic, 18:2 Linolenic, 18:3 Arachidic, 20:0 Eicosenoic, 20:1 Eicosadienoic, 20:2 Eicosatrienoic, 20:3 Behenoic, 22:0 Docosapentaenoic, 22:5 SFA4 MUFA PUFA UFA5 SFA:UFA
Barley
Corn 1
Corn 2
SEM
P-value
7 0.08 0.08 1.51 0.05 27.58 0.41 2.36 0.30 0.23a 16.00 34.07 11.33a 0.26 1.11 0.84a 0.53 0.08 0.39 0.10 47.73 40.18 12.37a 52.55 0.93
8 0.08 0.09 1.56 0.04 27.57 0.43 2.22 0.23 0.16b 15.69 33.69 14.48ab 0.30 0.97 0.84a 0.62 0.07 0.38 0.09 47.25 37.38 15.62ab 53.00 0.90
8 0.09 0.09 1.49 0.04 26.32 0.37 1.90 0.22 0.13b 15.74 33.85 15.60b 0.28 0.99 0.64b 0.57 0.08 0.38 0.09 45.99 37.50 16.74b 54.24 0.85
0.004 0.003 0.062 0.004 0.816 0.036 0.131 0.022 0.017 0.751 1.016 1.008 0.016 0.068 0.059 0.046 0.007 0.033 0.007 1.374 1.255 1.036 1.384 0.051
0.484 0.207 0.662 0.083 0.465 0.433 0.081 0.084 0.007 0.955 0.966 0.038 0.214 0.396 0.047 0.437 0.773 0.923 0.619 0.663 0.274 0.039 0.680 0.569
Values within a row with different letters differ (P < 0.05). Values are least squares means. Only those fatty acids with value equal to or in excess of 0.04% of the total fatty acid content are listed. 3 Number of replicate pens per diet. Pigs were housed 1 per pen. 4 Total SFA. 5 Total unsaturated fatty acids. a,b 1 2
ably the component responsible for the dietary differences observed in the concentration of PUFA in the backfat of the pigs. Others have reported a positive correlation between linoleic acid (18:2) and PUFA in pork fat (Averette Gatlin et al., 2002; Rentfrow et al., 2003). Despite the fact that the backfat from pigs fed the diet based on corn 2 had a higher concentration of PUFA compared with those fed the diet based on barley, the concentration of PUFA in the backfat of all pigs regardless of dietary treatment was within the range (less than 23%) recommended for salami making (Warnants et al., 1998). The fatty acid profiles of backfat of pigs fed the barley- and corn-based diets in the current study are similar to the values reported by Carr et al. (2005) for these feedstuffs. The differences in the fatty acid composition of barley and the 2 corn hybrids used in the current study did not affect the deposition of SFA and UFA in the backfat of pigs. The concentration of SFA and UFA in the backfat was not different across dietary treatments. Pigs fed the barley-based diet had a lower (P = 0.004) concentration of eicosatrienoic acid (20:3) in the belly fat compared with those fed the diet based on corn 2 (Table 7). The concentration of heptadecanoic acid (17:0) and heptadecenoic acid (17:1) were higher (P
