Effect of Phytase Addition on Growth and Carcass Traits of Pigs Fed Diets Deficient in Lysine, Calcium, and Phosphoruss1

The Professional Animal Scientist 25 (2009):169–174

©2009 American Registry of Professional Animal Scientists

Effect of Phytase Addition on Growth and Carcass Traits of Pigs Fed Diets Deficient in Lysine, Calcium, and Phosphorus1

S. L. Johnston, E. D. Frugé, T. D. Bidner, and L. L. Southern,2 PAS School of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge 708034210

ABSTRACT One hundred fifty gilts (initial and final BW 20 and 107 kg, respectively) were used in a 106-d experiment to determine the effects on growth performance and carcass traits of phytase addition to diets deficient in Lys, Ca, and P. The treatments were 1) positive control [NRC adequate in amino acids (AA), ME, Ca, and P]; 2) a diet with 85% of the Lys of diet 1, but adequate in Ca and P (85L+CaP); 3) 85L+CaP with 500 phytase units/kg phytase, expected to supply Lys, ME, Ca, and available P (aP; 85L-CaP+Phy); 4) 85L-CaP+Phy but with no added phytase (85L-CaP-Phy); and 5) 85L-CaP-Phy but adequate in Ca and P (85L+CaPE-AA). The nutrient matrix values used for the phytase addition were as follows: Ca 144%, aP 144%, ME 15,246 kcal/ kg, Lys 12%, Met 5%, Thr 5%, and Trp 2%. The phytase was provided at 0.083% of the diet and therefore was expected Approved for publication by the director of the Louisiana Agric. Exp. Stn. as Publ. No. 2009-230-2414. 2 Corresponding author: lsouthern@agctr. lsu.edu. 1

to provide the following nutrients: Ca 0.12%, aP 0.12%, ME 12.7 kcal/kg, Lys 0.01%, Met 0.004%, Thr 0.004%, and Trp 0.002%. Treatment diets were fed in a 4-phase feeding program. The standardized ileal digestible Lys levels in the control were 0.91, 0.79, 0.69, and 0.57% for diet changes at 20, 44, 68, and 87 kg, respectively. Each treatment was replicated 5 times with 6 gilts each. Pigs fed diets with reduced Lys concentrations had lower daily gain (P < 0.01) than pigs fed the control diet. Pigs fed 85L-CaP+Phy had G:F equal to, or slightly greater, than pigs fed the control or 85L+CaP, but pigs fed 85L-CaP+Phy had greater G:F than pigs fed 85L-CaPPhy (P < 0.05). Pigs fed a phytase-added diet with reduced levels of Lys, Ca, aP, and ME had G:F not different from, and slightly greater than, pigs fed the control or 85L+CaP. However, G:F was reduced in pigs fed 85L-CaP-Phy. Pigs fed 85LCaP+Phy had greater lean and backfat than pigs fed 85L+CaP. Phytase addition increased bone-breaking strength, but not to the level of pigs fed the diets with added Ca and aP. In conclusion, phytase addition improved utilization of Ca and P and some data (but not all) suggest

that phytase addition improved utilization of Lys and ME. Key words: pigs, phytase, amino acid, calcium, phosphorus

INTRODUCTION Phytate is an anionic compound with strong antinutritional effects; the best known antinutritional effect of phytate is that the P is mostly unavailable to nonruminants (Nelson et al., 1968). Amino acid (AA) availability of a feedstuff also may be inversely related to phytate concentration (Ravindran et al., 1999), but the effects of phytase on energy and AA availability are not consistent (Adeola and Sands, 2003; Selle and Ravindran, 2007). Phytate also has been shown to decrease the activity of digestive enzymes (Deshpande and Cheryan, 1984; Caldwell, 1992), bind to dietary proteins and AA, and form Ca-phosphate-phytate complexes with carbohydrate (Thompson and Yoon, 1984). Phytase in the diet increases the availability of phytate P for pigs (for

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Table 1. Experimental diets of grower period, as-fed basis1 Item

Control

85L+ CaP

Ingredient   Corn 67.11 72.61   Soybean meal 28.33 22.76   (47.5% CP)   Monocalcium phosphate 0.91 0.95   Limestone 0.79 0.82   Dry fat 1.85 1.85   Mineral premix3 0.10 0.10   Selenium premix4 0.05 0.05   Salt 0.40 0.40 0.38 0.38   Vitamin premix5   Phytase6 — —   Rice hulls 0.083 0.083 Calculated composition   ME, kcal/kg 3,400 3,400   CP, % 19.03 16.84   Lys, % 1.03 0.88   Thr, % 0.72 0.63   Trp, % 0.22 0.19   TSAA, % 0.64 0.58   SID Lys, % 0.91 0.77   SID Thr, % 0.62 0.54   SID Trp, % 0.20 0.17   SID TSAA, % 0.57 0.52   SID Thr:SID Lys 0.68 0.70   SID Trp:SID Lys 0.22 0.22   SID TSAA:SID Lys 0.63 0.68   Ca, % 0.60 0.60   P, % 0.55 0.54   Available phosphorus, % 0.24 0.24

85L-CaP+ Phy2 74.49 22.27 0.30 0.85 1.10 0.10 0.05 0.40 0.38 0.083 — 3,400 17.06 0.88 0.63 0.19 0.59 0.77 0.54 0.17 0.52 0.70 0.22 0.68 0.59 0.43 0.25

85L-CaPPhy 74.49 22.27 0.30 0.85 1.10 0.10 0.05 0.40 0.38 — 0.083 3,387 16.76 0.87 0.63 0.19 0.58 0.76 0.54 0.17 0.52 0.71 0.22 0.68 0.48 0.42 0.12

85L+CaPE-AA 73.56 22.47 0.88 0.97 1.10 0.10 0.05 0.40 0.38 — 0.083 3,387 16.73 0.87 0.63 0.19 0.58 0.76 0.54 0.17 0.51 0.71 0.22 0.67 0.60 0.55 0.25

Diets for the finisher 1, 2, and 3 phases were corn-soybean meal diets similar to the grower diet, but the standardized ileal digestible (SID) Lys level in diet 1 (positive control) was 0.79, 0.69, and 0.57% in the finisher 1, 2, and 3 phases, respectively. Control = corn-soybean meal (adequate in amino acids, ME, Ca, and P); 85L+CaP = diet with 85% of the Lys of diet 1, but adequate in Ca and P; 85L-CaP+Phy = 85L+CaP, but formulated to contain 500 FTU/kg of phytase, expected to supply amino acids, ME, Ca, and P; 85L-CaP-Phy = 85L-CaP+Phy with no added phytase; 85L+CaP-E-AA = 85L-CaP-Phy, but adequate in Ca and P.

1

Calculated composition includes nutrient values provided by phytase. The nutrient matrix values that were used for the phytase addition were Ca, 144%; available P, 144%; ME, 15,246 kcal/kg; Lys, 12%; Met, 5%; Thr, 5%; and Trp, 2%. Therefore, the phytase, provided at 0.083% of the diet, was expected to provide the following nutrients: Ca, 0.12%; aP, 0.12%; ME, 12.7 kcal/kg; Lys, 0.01%; Met, 0.004%; Thr, 0.004%; and Trp, 0.002%.

2

Provided the following milligrams per kilogram of diet: Zn, 127; Fe, 127; Mn, 20; Cu, 12.7; and I, 0.80, as zinc sulfate, ferrous sulfate, manganese sulfate, copper sulfate, and calcium iodate, respectively, with calcium carbonate as the carrier.

3

4

Provided 0.3 mg/kg of diet.

Provided the following per kilogram of diet: vitamin A, 8,267 IU; vitamin D, 2,480 IU; vitamin, E 66 IU; menadionine (as menadionine pyrimidinol bisulfite complex), 6.2 mg; riboflavin, 10 mg; Ca-d-pantothenic acid, 37 mg; niacin, 66 mg; vitamin B12, 45 μg; d-biotin, 331 μg; folic acid, 2.5 mg, pyridoxine, 3.31 mg, thiamine, 3.31 mg; and vitamin C, 83 μg. 5

The 0.083% phytase provided 500 FTU/kg diet (Natuphos 600, BASF Corp., Mt. Olive, NJ).

6

a review, see Selle and Ravindran, 2007). Because of the effect of phytate on dietary and digestive proteins, phytase might also be expected to increase the availability of AA in feeds. Improved digestibility of DM, CP (Mroz et al., 1994), and AA (Radcliffe et al., 1999; Johnston et al., 2004) has been reported with phytase addition to swine diets. However, other research has reported no change in DM or N digestibility (Jongbloed et al., 1992; O’Quinn et al., 1997; Adeola and Sands, 2003) with phytase addition. Selle and Ravindran (2007) reviewed the most current data on the effect of phytase on the digestibility of AA and outlined some of the reasons for the controversy. Thus, the objective of this experiment was to determine the effect of phytase on Ca, P, AA, and energy utilization in pigs.

MATERIALS AND METHODS The materials and methods used in this experiment were approved by the Louisiana State University Agricultural Center Animal Care and Use Committee. One hundred fifty gilts (PIC commercial hybrid, Hendersonville, TN) with an average initial BW of 20.1 kg were allotted to 5 dietary treatments with 5 replications of 6 gilts each in a completely randomized design. Pigs were allowed to consume feed and water on an ad libitum basis and were housed in an open-sided finishing barn in 1.52- × 4.27-m pens with floors that were aluminum slats (1.52 × 2.44 m) and solid concrete (1.52 × 1.83 m). The experimental period lasted 106 d, and the average final BW was 107.2 kg. The diets in mash form were fed in a 4-phase feeding program. The treatment diets were 1) positive control (PC; NRC adequate in AA, ME, Ca, and P); 2) a diet with 85% of the Lys of control, but adequate in Ca and P (85L+CaP); 3) 85L+CaP with 500 phytase units (FTU)/kg phytase expected to supply Lys, ME, Ca, and available P (aP; 85L-CaP+Phy); 4) 85L-CaP+Phy but with no added phytase (85L-CaP-Phy); and 5) 85L-CaP-Phy but adequate in Ca and

P (85L+CaP-E-AA). The standardized ileal digestible Lys levels in the control were 0.91, 0.79, 0.69, and 0.57% for diet changes at 20.1, 44.1, 68.4, and 86.8 kg BW. The control diet was adequate in all nutrients (NRC, 1998) for gilts gaining 325 g/d of lean. The remaining 4 diets were formulated to provide 85% of the Lys concentration of the control, which would allow a response surface for growth and carcass trait criteria to change because of dietary treatment. Diets (Table 1) were formulated on a standardized ileal digestible AA basis using the digestibility coefficients of NRC (1998). The nutrient matrix values that were used for the phytase addition were as follows: Ca, 144%; aP, 144%; ME, 15,246 kcal/kg; Lys, 12%; Met, 5%; Thr, 5%; and Trp, 2%. The phytase was provided at 0.083% of the diet and therefore was expected to provide Ca, 0.12%; aP, 0.12%; ME, 12.7 kcal/kg; Lys, 0.01%; Met, 0.004%; Thr, 0.004%; and Trp 0.002%. Nutrient matrix values were those suggested by the manufacturer of the phytase product (Natuphos 600, BASF Corp., Mount Olive, NJ). In the diets with 85% of the Lys of the control, the Lys level was changed by changing the ratio of corn to SBM; thus, the ratios of AA to Lys changed as noted in Table 1. However, all AA-to-Lys ratios in all diets exceeded those recommended by NRC (1998). At the termination of the experiment, 3 gilts/pen were randomly selected for slaughter. Pigs were slaughtered by electrical stunning followed by exsanguination, and hot carcass weights were obtained for calculation of dressing percentage. Carcass measurements and values from total body electrical conductivity (TOBEC; Model MQI-27, Meat Quality Inc., Springfield, IL) analysis were obtained from the left side of the carcass after a 20-h chill at 2°C. Fat-free lean and total fat contents were determined by TOBEC analysis. The following equation from Higbie et al. (2002) was used to calculate kilograms of fat-free lean: {[−2.164 + (0.172 × carcass length) + (0.164 × peak TOBEC value) − (0.742 × carcass tempera-

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ture)] × 2}. The following equation from Higbie (1997) was used to calculate kilograms of total fat: {[−9.528 + (0.660 × cold carcass side weight) + (1.181 × 10th-rib backfat) − (0.132 × peak TOBEC value) + (0.465 × carcass temperature)] × 2}. Percentage lean was calculated with the equation: fat free lean/hot carcass weight × 100; percentage fat was calculated with the equation: total fat/hot carcass weight × 100. Lean gain per day was calculated using the equation: (fat free lean − initial lean)/ number of days on trial. Initial lean was determined using the equation of Brannaman et al. (1984): −1.59 + 0.44 × initial BW. The third and fourth metacarpal bones from the right foot of each pig were removed at the time of slaughter and manually cleaned of adhering tissue. Bones were broken using an Instron Universal Testing Machine (Model 4301, Instron Corp., Canton, MA) with a load cell capacity of 500 kg, a speed of 30 mm/min, and a bridge width of 3.6 cm. The mean of the 2 bones was used for the analysis of bone-breaking strength. Data from this experiment were analyzed by ANOVA procedures appropriate for a completely randomized design using the GLM procedure (SAS Inst. Inc., Cary, NC). Individual pig initial BW was used as a covariate for the growth data. Individual pig final BW was used as a covariate for all carcass data. The treatment × replication term was used as the error term in the analysis of the growth and carcass data. Single degreeof-freedom contrasts were used to determine treatment differences. Contrasts used were as follows: 1) control vs. all other diets; 2) 85L+CaP vs. 85L-CaP+Phy; 3) 85L-CaP+Phy vs. 85L-CaP-Phy; 4) 85L-CaP+Phy vs. 85L+CaP-E-AA; and 5) 85L-CaP-Phy vs. 85L+CaP-E-AA. The pen of pigs was the experimental unit for all data.

with pigs fed the control diet. Pigs fed 85L+CaP-E-AA tended to have increased (P < 0.10) ADG compared with pigs fed 85L-CaP-Phy. Pigs fed 85L-CaP+Phy had reduced (P < 0.05) ADFI compared with pigs fed 85L+CaP-E-AA. Gain:feed was greater (P < 0.05) in pigs fed 85LCaP+Phy than in pigs fed 85L-CaPPhy. Fat-free lean, percentage lean, and lean gain per day were greater (P < 0.01 to 0.05) and lean-to-fat ratio tended to be greater (P < 0.09) in pigs fed the control diet than in pigs fed the diets with reduced Lys concentrations. Pigs fed 85L-CaP+Phy had greater 10th-rib backfat (P < 0.02), dressing percentage (P < 0.02), fat-free lean (P < 0.03), and lean gain per day (P < 0.04) than pigs fed 85L+CaP. Lean gain per day (P < 0.05) and dressing percentage (P < 0.06) were greater in pigs fed 85LCaP+Phy than in those fed 85L-CaPPhy. Bone-breaking strength (Table 3) was greater (P < 0.03) in pigs fed 85L-CaP+Phy than in those fed 85LCaP-Phy. However, bone-breaking strength of pigs fed 85L-CaP+Phy was less (P < 0.01) than that of pigs fed 85L+CaP. The greater ADG and ADFI in pigs fed the control diet compared with those fed diets with reduced Lys concentrations was expected because reduced growth and feed intake are characteristic signs of AA deficiencies in swine (NRC, 1998). Average daily gain was not different in pigs fed 85L+CaP compared with pigs fed 85L-CaP+Phy. Zhang and Kornegay (1999) showed linear increases in ADG when phytase (250 or 500 FTU/kg) was added to low-protein diets for pigs. Pigs fed the diet using the phytase nutrient matrix values for ME and AA but with adequate Ca and aP (85L+CaP-E-AA) had higher ADG than pigs fed the diet using phytase matrix values for ME, AA, Ca, and aP but without phytase (85L-CaP-Phy). This response would be expected because diets deficient in aP are associated with decreased gain (Cromwell et al., 1991; Potter

RESULTS AND DISCUSSION Pigs fed all diets with reduced Lys concentrations (Table 2) had reduced ADG and ADFI (P < 0.01) compared

Not significant, P > 0.20. 3

The treatments were as follows: control = corn-soybean meal (adequate in amino acids, ME, Ca, and P); 85L+CaP = diet with 85% of the Lys of diet 1, but adequate in Ca and P; 85L-CaP+Phy = 85L+CaP, but formulated to contain 500 FTU/kg of phytase, expected to supply amino acids, ME, Ca, and P; 85L-CaP-Phy = 85L-CaP+Phy with no added phytase; 85L+CaP-E-AA = 85L-CaP-Phy, but adequate in Ca and P.

The experimental period was 106 d. Data are means of 5 replicates of 6 gilts. Initial BW (20 kg) was used as a covariate. 1

2

0.10 NS NS 0.09 NS 0.05 0.15 NS NS NS 0.05 NS NS3 NS NS NS 0.01 0.01 NS 0.01 0.021 0.07 6 2.3 0.829 2.46 337 108.3 0.776 2.36 330 102.3 0.793 2.25 352 104.2 0.896 2.60 345 115.4 ADG, kg ADFI, kg G:F, g/kg Final BW, kg

0.815 2.36 345 106.6

85L-CaP-Phy vs. 85L+CaP-E-AA 85L-CaP+Phy vs. 85L+CaP-E-AA 85L-CaP+Phy vs. 85L-CaP-Phy 85L+CaP vs. 85L-CaP+Phy Control vs. all SEM 85L+CaPE-AA 85L-CaP+ 85L-CaPPhy Phy 85L+ CaP Control Item

Contrast, P > F

et al., 1995). Increasing the availability of phytate P by phytase addition reversed this response. Feed intake was not different for pigs fed 85L+CaP compared with 85L-CaP+Phy, but ADFI was lower in pigs fed the diet with added phytase than in pigs fed the diet using the phytase matrix values for ME and AA, but with adequate Ca and aP (85L+CaP-E-AA). The reduction of ADFI with phytase addition may be due to increased energy availability because pigs eat to a constant energy intake (Ewan, 1991), and phytase has been shown to increase available energy in diets for pigs (Shelton et al., 2003). Pigs fed the control diet did not have G:F greater than pigs fed the diets with reduced Lys concentrations. Pigs fed 85L-CaP+Phy had G:F equal to that of pigs fed 85L+CaP, but they had greater G:F than pigs fed 85LCaP-Phy and tended to have greater G:F than pigs fed 85L+CaP-E-AA. This response is in agreement with the reports of other researchers who reported increased feed efficiency with phytase addition to diets for swine (Cromwell et al., 1991; Young et al., 1993), but is in contrast to the reports of others who reported no effect on feed efficiency (Lei et al., 1993; O’Quinn et al., 1997). This result suggests that not all the increased feed efficiency from phytase was in response to increased Ca and P, but that energy availability was improved when phytase was added to the diet. This response supports the suggestion that decreased feed intake with phytase addition was due to increased energy availability. Pigs fed the control diet had greater fat free lean, percentage lean, lean gain per day, and lean-to-fat ratio than pigs fed the diets deficient in Lys. This response indicates that these criteria would respond to an increase in AA concentration or availability in the diet. Pigs fed the diet containing phytase had greater fat free lean and lean gain per day and a tendency for a greater percentage of lean than pigs fed the diet without phytase (85L+CaP). This response is

Johnston et al.

Table 2. Effect of phytase addition on growth performance of growing-finishing pigs fed diets varying in Lys, energy, Ca, and P1,2

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1.44 44.72 72.52 43.91 55.36 25.32 20.27 339 2.27 182.0

10th-rib 3/4 backfat, cm LM area, cm2 Dressing percent Fat free lean, kg Percentage lean Percentage fat Total fat, kg Lean gain per day, g Lean:fat Bone-breaking strength, kg

1.66 44.15 73.71 43.42 53.34 25.89 21.53 329 2.12 149.8

1.53 44.29 72.36 41.97 52.64 26.18 21.08 310 2.06 120.8

1.44 43.05 72.86 42.44 52.38 26.32 21.65 316 2.07 179.4

0.11 1.80 0.44 0.63 0.80 0.97 0.74 6.40 0.10 8.42

NS3 NS NS 0.04 0.01 NS NS 0.01 0.09 0.03

85L-CaP- 85L+CaPControl Phy E-AA SEM vs. all 0.02 NS 0.02 0.03 0.15 NS NS 0.04 NS 0.01

85L+CaP vs. 85LCaP+Phy NS NS 0.06 NS NS NS NS 0.05 NS 0.03

85L-CaP+Phy vs. 85LCaP-Phy

0.17 NS NS NS NS NS NS NS NS 0.03

85L-CaP+Phy vs. 85L+ CaP-E-AA

NS NS NS NS NS NS NS NS NS 0.01

85L-CaP-Phy vs. 85L+ CaP-E-AA

3

2

Not significant, P > 0.20.

The treatments were as follows: control = corn-soybean meal (adequate in amino acids, ME, Ca, and P); 85L+CaP = diet with 85% of the Lys of diet 1, but adequate in Ca and P; 85L-CaP+Phy = 85L+CaP, but formulated to contain 500 FTU/kg of phytase, expected to supply amino acids, ME, Ca, and P; 85L-CaP-Phy = 85L-CaP+Phy with no added phytase; 85L+CaP-E-AA = 85L-CaP-Phy, but adequate in Ca and P.

1

Data are least squares means (except bone-breaking strength) of 5 replicates of 3 gilts each per pen. Three pigs were selected at random from each replicate for analysis of carcass characteristics. Final BW was used as a covariate for all carcass data and was significant (P < 0.03) for all response criteria except for dressing percentage (P = 0.31). Final BW was not used as a covariate for bone-breaking strength; thus, these data are not least squares means.

1.24 44.16 72.00 41.37 51.65 25.96 20.89 308 2.01 187.0

Control 85L+CaP

Item

85L-CaP+ Phy

Contrast, P > F

Table 3. Least squares means of the effect of phytase addition on carcass characteristics in growing-finishing pigs fed diets varying in Lys, energy, Ca, and P1,2

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in contrast to O’Quinn et al. (1997), who reported no changes in percentage lean in pigs as a result of phytase addition to sorghum- and soybean meal-based diets, and of Gebert et al. (1999), who reported that phytase had no effect on carcass composition of pigs fed barley- and maize-based diets. However, these reports were in pigs fed diets adequate in Lys; therefore, it is unlikely that these pigs would have shown an increase in lean composition if there had been an increased in AA availability due to phytase addition.. Bone-breaking strength of pigs fed the diet with added phytase was greater than that of pigs fed that diet without added phytase. However, bone-breaking strength of pigs fed the diet with added phytase was lower than that of the pigs fed diets with higher dietary Ca and P concentrations. This reduced bone-breaking strength suggests that 500 FTU/ kg did not provide the 0.12% Ca and aP that was projected from the nutrient matrix values. This response is in agreement with Cromwell et al. (1995), who reported increases in bone-breaking strength but only the 1,000 FTU/kg phytase diet approached the bone strength of the positive control, but in contrast to O’Quinn et al. (1997), who reported that bone strength was higher than that of the control diet with addition of 300 FTU/kg of phytase.

IMPLICATIONS The results of this research indicate that phytase addition increased available Ca and P in diets for swine, but not to the extent as expected. The data also indicate that phytase addition increased lean gain in pigs and that it may increase energy availability in the diet, based on some responses but not on others. More research is needed to identify the extent of the non-P effects of phytase.

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