J. Anim. Sci. 2004. 82:2397-2404
© 2004 American Society of Animal Science
Utilization of spray-dried blood cells and crystalline isoleucine in nursery pig diets1
B. J. Kerr*,2,
M. T. Kidd
,
J. A. Cuaron
,
K. L. Bryant
,
T. M. Parr¶,
C. V. Maxwell# and
E. Weaver**
* USDA-ARS, Swine Odor and Manure Management Research Unit, Ames, IA 50011-3310;
and
Mississippi State University, Mississippi State 39762-9665;
and
Centro Nacional de Investigacion en Fisiologia y Mejoramiento Animal, INIFAP, Queretaro, Mexico 76020;
and
Akey, Lewisburg, OH 45338;
and
¶ University of Illinois, Urbana 61801;
and
# University of Arkansas, Fayetteville 72701; and
and
** Proliant Inc., Ames, IA 50011
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Abstract
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Three experiments were conducted to evaluate spray-dried blood cells (SDBC) and crystalline isoleucine in nursery pigs. In Exp. 1, 120 pigs were used to evaluate 0, 2, 4, and 6% SDBC (as-fed basis) in a sorghum-based diet. There were six replicates of each treatment and five pigs per pen, with treatments imposed at an initial BW of 9.3 kg and continued for 16 d. Increasing SDBC from 0 to 4% had no effect on ADG, ADFI, and G:F. Pigs fed the 6% SDBC diet had decreased ADG (P < 0.01) and G:F (P = 0.06) compared with pigs fed diets containing 0, 2, or 4% SDBC. In Exp. 2, 936 pigs were used to test diets containing 2.5 or 5% SDBC (as-fed basis) vs. two control diets. There were six replicates of each treatment at industry (20 pigs per pen) and university (six pigs per pen) locations. Treatments were imposed at an initial BW of 5.9 and 8.1 kg at the industry and the university locations, respectively, and continued for 16 d. Little effect on pig performance was noted by supplementing 2.5% SDBC, with or without crystalline Ile, in nursery diets. Pigs fed the 5% SDBC diet without crystalline Ile had decreased ADG (P < 0.01), ADFI (P 
0.10), and G:F (P < 0.05) compared with pigs fed the control diets. Supplementation of Ile restored ADG, ADFI, and G:F to levels that were not different from that of pigs fed the control diets. In Exp. 3, 1,050 pigs were used to test diets containing 5, 7.5, or 9% SDBC (as-fed basis) vs. a control diet. There were six replicates of each treatment at the industry (20 pigs per pen) location and five replicates at the university (six pigs per pen) locations. Treatments were imposed at an initial BW of 6.3 and 7.0 kg at the industry and university locations, respectively, and continued for 16 d. Supplementation of 5% SDBC without crystalline Ile decreased ADG and G:F (P < 0.01) compared with pigs fed the control diet, but addition of Ile increased ADG (P < 0.01) to a level not different from that of pigs fed the control diet. The decreased ADG, ADFI, and G:F noted in pigs fed the 7.5% SDBC diet was improved by addition of Ile (P < 0.01), such that ADG and ADFI did not differ from those of pigs fed the control diet. Pigs fed diets containing 9.5% SDBC exhibited decreased ADG, ADFI, and G:F (P < 0.01), all of which were improved by Ile addition (P < 0.01); however, ADG (P < 0.05) and G:F (P = 0.09) remained lower than for pigs fed the control diet. These data indicate that SDBC can be supplemented at relatively high levels to nursery diets, provided that Ile requirements are met.
Key Words: Blood cells • Isoleucine • Nursery Pigs
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Introduction
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Blood meal is an animal protein product containing high levels of CP, Lys, and Val, but low concentrations of Ile and Met (NRC, 1998
). Older, conventional methods for drying blood resulted in a product of poor palatability with low CP and AA availability (Kratzer and Green, 1957; Waibel et al., 1977), such that it was generally limited to 3% in swine diets. Newer methods of drying blood have resulted in high availability of Lys (Southern, 1991), so that up to 6% blood meal may be used in nursery diets without affecting pig performance (Parsons et al., 1985; Hansen et al., 1993; Kats et al., 1994).
A coproduct of the porcine plasma production process is spray-dried blood cells (SDBC), which have also been used in piglet diets, but to a lesser extent than porcine plasma. The AA characteristics of this product also show high concentrations of Leu, Lys, and Val, but a limited concentration of Ile (NRC, 1998). Research has shown 2.5% SDBC can be substituted for other protein sources in pig diets without affecting pig performance (Beltranena et al., 1996; Feng et al., 1996; Woodworth et al., 1996). Nonetheless, research strictly evaluating graded levels of SDBC is limited. Zhang et al. (1999) indicated that 3.6% SDBC decreased pig performance compared with pigs fed diets containing 2.7% SDBC, whereas DeRouchey et al. (2002) fed 7.5% SDBC with no negative effect on pig performance. Research showing why SDBC cannot be supplemented at higher levels in nursery pig diets is limited, although recent growing-finishing pig research (Kerr et al., 2002; Parr et al., 2003, 2004) suggests that the "palatability" concern when using blood products in swine diets may be a result of its Ile content.
The current experiments were conducted to evaluate the use of SDBC in nursery diets and determine the ability of crystalline Ile to overcome the growth-depressing effects in diets containing high levels of SDBC owing to their potential limitation in Ile content.
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Experimental Procedures
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All experimental procedures followed the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 1999).
Experiment 1.
A preliminary experiment involving a total of 120 pigs (Duroc sires x Landrace dams) were used to determine the level of SDBC (AP 301G; APC Inc., Ankeny, IA) that could be fed to elicit an Ile deficiency. Pigs were weaned at an average of 24 d of age and housed in an enclosed insulated building with temperature and humidity controlled by an exhaust fan and natural ventilation. After weaning, pigs were fed a common Phase I diet for 10 d, which contained 20% CP, 1.31% total Lys, and 3.27 ME Mcal/kg, including 5% spray-dried animal plasma. Pigs were subsequently allotted to elevated pens with wire mesh flooring, 1.5 m x 1.0 m, with each pen containing a seven-hole feeder providing 0.85 m of trough space and a single nipple watering device.
Diets (Table 1) were formulated on an apparent digestible AA basis using the total CP and AA values of sorghum, soybean meal, meat and bone meal, and SDBC (NRC, 1998), AA digestibility estimates (Southern, 1991; E. Weaver, personal communication, APC, Inc.), and balanced relative to digestible Lys, except for Ile, according to Baker (1997). Diets were formulated to 3,230 kcal ME/kg and 1.10% digestible Lys. Spray-dried blood cells were added at 0, 2, 4, and 6% (as-fed basis) of the diet with sorghum, soybean meal, and crystalline AA adjusted to meet the defined nutrient restrictions. Dietary treatments were imposed at an average initial BW of 9.3 kg and continued for 16 d. Pigs were allowed ad libitum access to feed and water. Individual pig weights and feed disappearance recorded at the end of 16 d to calculate ADG, ADFI, and G:F.
There were six replicates of each treatment in a randomized complete block design. Blocks were formed on the basis of gender and weight. Assignment to treatment was done randomly from within blocks, with three blocks consisting of three gilts and two barrows, and three blocks consisting of two gilts and three barrows. Data for each response criterion were analyzed by ANOVA using the GLM procedure of SAS (2001), with replicate and dietary treatment included in the model. The pen of pigs was used as the experimental unit for all data. The PDIFF option of SAS was used to determine differences between treatment means.
Experiment 2.
Seven hundred twenty pigs (Line 326 sire x C22 dams; Pig Improvement Company, Franklin, KY) at an industry research location and 216 pigs (Hampshire x Duroc sires mated to Yorkshire x Landrace dams) at the University of Arkansas were used to further develop an Ile-deficient diet for 6- to 15-kg pigs through the use of SDBC in a corn/soybean meal/whey/fish meal-based diet. At each location, pigs were weaned at approximately 18 d of age and fed a common Phase I diet for 8 and 5 d at the industry and university locations, respectively. At the industry location, pens were 1.65 m x 3.0 m. Floors were 100% plastic slats, feed was provided with a feeder with 0.76 m of trough space, and water was provided by two nipple waters. At the University of Arkansas, pigs were housed in an environmentally controlled off-site nursery facility in pens (1.63 m x 1.19 m) with two nipple waterers, a five-hole feeder, and Maxima nursery flooring (Agra Flooring Int. Ltd., Calgary, Alberta, Canada). Pigs at each location were allowed ad libitum access to feed and water. Pigs were offered the experimental diets for 16 d, with individual pig weights and feed disappearance recorded at the end of 16 d to calculate ADG, ADFI, and G:F.
Diets included corn, soybean meal, whey, and fish meal, with SDBC supplemented at levels of 2.5 and 5.0% (as-fed basis), with and without crystalline Ile. In addition, high- and low-CP diets were formulated as controls. Nitrogen analyses of ingredients and mixed diets were conducted using the macro-Kjeldahl procedure (AOAC, 1984) and CP was calculated (N x 6.25). Amino acid concentrations of ingredients and mixed diets were determined following acid hydrolysis, Trp concentrations following alkaline hydrolysis, and Met and Cys following performic acid oxidation (AOAC, 1984) using a high-performance cation exchange resin column (Beckman Systems Inc., Fullerton, CA). Diets were formulated on an apparent digestible AA basis using the AA composition of the ingredients (Table 2), AA digestibility estimates (Southern, 1991; E. Weaver personal communication, APC Inc.), and balanced relative to digestible Lys with Trp:Lys, Thr:Lys, total sulfur AA (TSAA):Lys, and Val:Lys ratios of 0.18, 0.68, 0.60, and 0.71, respectively (Table 3). These values are higher than ratios according to Baker (1997) but were used to ensure no deficiencies owing to the lack of peer-reviewed digestibility estimates for dried blood cells. Crystalline Ile replaced cornstarch in the diets containing SDBC and was supplemented to achieve an apparent digestible Ile:Lys ratio of 0.66. A high-CP control diet was formulated to minimize the level of crystalline AA supplementation, whereas a low-CP control diet maximized the level of crystalline AA to substantiate that inclusion of crystalline AA have no impact on pig performance. All feed was mixed and bagged at the industry location, with an adequate amount shipped to the University of Arkansas to complete the trial. Dietary treatments were imposed for 16 d, with an average initial BW of 5.9 kg at the industry location and 8.1 kg at the University of Arkansas.
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Table 2. Amino acid composition (%) of dietary ingredients and apparent amino acid digestibility (%) of spray-dried blood cells (as-fed basis)
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At each location, there were six replicates of each treatment in a randomized complete block design. Blocks were formed on the basis of gender and weight. Assignment to treatment was done randomly from within blocks with 20 pigs per pen (gender equally represented across treatments) at the industry location and six pigs (barrows) per pen at the University of Arkansas. Data for each response criterion were analyzed by ANOVA using the GLM procedure of SAS (2001) with location, replicate, and dietary treatment included in the model. The pen of pigs was used as the experimental unit for all data. The PDIFF option of SAS was used to determine differences between treatment means.
Experiment 3.
Eight hundred forty pigs at the industry research location and 210 pigs at the University of Arkansas were used to refine the Ile-deficient diet tested in Exp. 2. Pigs were housed and managed as described in Exp. 2. Using the same batch of SDBC, dried whey, and fish meal, but different batches of corn and soybean meal, diets (Table 4) were formulated as described in Exp. 2, except that 5.0, 7.5, and 9.5% SDBC (as-fed basis) were incorporated into the test diets, with and without crystalline Ile, and only a low-CP, AA-supplemented diet was used as the control. In addition, the Trp:Lys ratio was increase to 0.19, the Thr:Lys increased to 0.72, the TSAA:Lys ratio increased to 0.66, and the Val:Lys ratio increased to 0.75 as additional precautions to ensure no amino acid deficiencies. Crystalline Ile replaced cornstarch in the diets containing SDBC and was supplemented to achieve an apparent digestible Ile:Lys ratio of 0.66. As in Exp. 2, all feed was mixed and bagged at the industry location with an adequate amount shipped to the University of Arkansas to complete the trial. Dietary treatments were imposed for 16 d with an average initial BW of 6.3 kg at the industry location and 7.0 kg at the University of Arkansas.
There were six replicates of each treatment with 20 pigs per pen at the industry location and five replicates of each treatment with six pigs per pen at the University of Arkansas, each in a randomized complete block design. Blocks were formed on the basis of gender, ancestry, and weight, and assignment to treatment was done randomly. Blocking of animals, assignment to treatment, and data analysis were as described in Exp. 2.
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Results
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Experiment 1.
Increasing SDBC from 0 to 4% had no impact on ADG, ADFI, and G:F, Table 5. Pigs fed the diet containing 6% SDBC had decreased ADG (P < 0.01) and G:F (P = 0.06) compared with pigs fed either the control diet or diets containing 2.0 or 4.0% SDBC. Pigs fed 6% SDBC tended to have decreased ADFI (P = 0.12) compared with pigs fed 0% SDBC.
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Table 5. Performance by pigs fed graded levels of spray-dried blood cells in a sorghum/soybean meal/meat and bone meal-based diet, Exp. 1 (as-fed basis)a
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Experiment 2.
There was no difference in performance between pigs fed the high- or low-CP control diets (P 
0.66), Table 6. Although pigs fed the diet containing 2.5% SDBC without crystalline Ile grew faster than pigs fed either control diet (P < 0.05), there was no effect of supplementing 2.5% SDBC, with or without crystalline Ile, on ADFI or G:F compared with pigs fed the control diets (P 0.38). Compared with either control diet, supplementation of 5.0% SDBC without crystalline Ile decreased ADG (P < 0.01), ADFI (P 0.10), and G:F (P < 0.05). Supplementation of 0.255% crystalline Ile to the diet containing 5.0% SDBC increased ADG (P < 0.01), ADFI (P = 0.06), and G:F (P < 0.01) to a level not different from that of pigs fed the control diets.
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Table 6. Performance of pigs fed graded levels of spray-dried blood cells in a corn/soybean meal/dried whey/fish meal-based diet, Exp. 2 (as-fed basis)a
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Experiment 3.
Supplementation of 5.0% SDBC without crystalline Ile decreased ADG and G:F (P < 0.01) compared with pigs fed the low-CP control diet (Table 7). Addition of 0.248% crystalline Ile increased ADG (P < 0.01) and numerically increased G:F (P = 0.23) to levels not different from that of pigs fed the control diet (P 0.17). Supplementation of 5.0% SDBC, with or without crystalline Ile, had no effect of ADFI compared with pigs fed the control diet. Supplementation of 7.5% SDBC decreased ADG, ADFI, and G:F relative to pigs fed the control diet (P < 0.01), all of which were improved by addition of 0.36% crystalline Ile (P < 0.01). Although adding Ile increased ADG and ADFI to a level not different from that of pigs fed the control diet, G:F tended to remain lower than pigs fed the control diet (P = 0.12). Supplementation of 9.5% SDBC dramatically decreased ADG, ADFI, and G:F (P < 0.01), all of which were improved by addition of 0.476% crystalline Ile (P < 0.01). Although the improvement of ADFI equaled that of pigs fed the control diet, ADG (P < 0.05) and G:F (P = 0.09) remained lower than that of pigs fed the control diet.
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Table 7. Performance of pigs fed graded levels of dried blood cells in a corn/soybean meal/dried whey/fish meal-based diet, Exp. 3 (as-fed basis)a
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Discussion
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In Exp. 1, inclusion of up to 4.0% SDBC had no effect on pig performance, whereas pigs fed a diet containing 6.0% SDBC had reduced performance. This finding suggests that digestible Ile levels below 0.54% fed to 9- to 15-kg pigs may have a detrimental effect on pig performance. This is in contrast with the results of Zhang et al. (1999), who suggested that no more than 2.7% SDBC could be supplemented to the diet. Evaluation of their data, however, showed that they used smaller pigs, 6 to 9 kg, and their diet containing 3.6% SDBC may have been marginally limiting in Ile as well as Thr. To prevent this, our subsequent experiments provided an additional 10% increase in the ideal AA ratios for Trp, Thr, TSAA, and Val above the ratio suggested by Baker (1997). Although SDBC accounts for approximately 75% of the total solids found in blood meal, comparison of our data using SDBC to research evaluating blood meal (Wahlstrom and Libal, 1977; Hansen et al., 1993; Kats et al., 1994) is difficult. Regardless, this comparison suggests that approximately 4.5% SDBC could be fed to nursery pigs, assuming a maximum of 6.0% blood meal inclusion level. The fact that pigs in Exp. 1 could utilize higher levels of SDBC, or not be affected by lower levels of digestible Ile, compared with Exp. 2 and 3 is interesting. Pigs used in Exp. 1 were from a different genetic source, were weaned 6 d later, and were kept on a common diet for 5 d longer than pigs in Exp. 2 and 3. Consequently, these pigs were 11 d older at the initiation of the experiment, with a 2- to 3-kg heavier average BW than pigs used in subsequent experiments. As a result, these pigs had greater feed intake so that feeding higher levels of SDBC, or lower levels of digestible Ile, did not affect performance as noted in Exp. 2 and 3. This clearly supports the common knowledge that in experiments evaluating different ingredients or AA levels, the level of feed intake has a dramatic effect on interpretation of the data.
Refocusing our efforts on a more typical Phase II diet fed in the United States, Exp. 2 confirmed that 2.5% SDBC supplementation would have no effect on pig performance. This was expected when compared with Zhang et al. (1999) and was due to digestible Ile levels that were above NRC (1998) recommendations. Supplementation of 5.0% SDBC, 0.58% digestible Ile, resulted in decreased feed intake and, consequently, pig performance. With the small reduction in pig performance that was alleviated by crystalline Ile supplementation, it was felt that 0.58% digestible Ile was slightly below the digestible Ile needs of pigs weighing 7 to 13 kg. However, because the decreased performance was only 15% for growth rate and 8% for feed intake and feed efficiency, it was thought that this level of decreased performance would not be adequate for subsequent Ile requirement-type experiments. Thus, Exp. 3 utilized higher levels of SDBC.
The decreases in feed intake of 7, 21, and 22% observed when feeding approximately 95, 77, and 57% of the estimated Ile requirement (5.0, 7.5, and 9.5% SDBC, respectively) were not expected. Deficiencies of Ile have been shown to have a dramatic decrease in feed intake in pigs (Seve, 1999) and poultry (Kino and Okumura, 1986), but not to the degree noted in Exp. 3. Likewise, the ability of crystalline Ile to reverse this depression in feed intake was astounding, essentially allowing for equivalent performance compared with pigs fed the control diet. As a result, a diet containing 7.5% SDBC should provide an excellent opportunity from which to evaluate Ile requirements and Ile:Lys ratios in nursery pigs because the decrease in growth rate of 47%, feed intake of 21%, and feed efficiency of 29% could be overcome with only crystalline Ile supplementation. Recent data by DeRouchey et al. (2002) supports our data, indicating that up to 7.5% SDBC can be utilized in nursery pigs diets provided that limiting amino acids are supplemented to the diet.
In chicks fed high levels of dietary Leu, as much as 70% of the decreased growth rate has been shown to be due to a depression in food intake (Calvert et al., 1982). Although it could be speculated that a large portion of the growth-depressing effects from feeding SDBC in our studies was a result of its Leu content, 12.5% vs. 0.90% in corn and 3.6% in soybean meal, it could equally be argued that the increase in digestible Leu from 1.5% in the low-CP control to 2.1% in the diet containing 9.5% SDBC was not the major limitation with feeding SDBC. In Exp. 3, the greatest decrease in feed intake was 25% when comparing feed intakes of pigs fed diets containing 9.5% SDBC without crystalline Ile to pigs fed the low-CP control, yet feed efficiency was reduced 70%. This too was corrected by supplementation of crystalline Ile. Recently, Parr (2003) showed that addition of 1.0% Leu plus 0.5% Val can decrease feed intake and growth rate in 27- to 38-kg pigs fed a semipurified diet, but no effect on feed efficiency was noted. In contrast, Edmonds and Baker (1987) showed that up to 4% supplemental Leu did not affect pig performance when added to a typical corn-soybean meal-based diet.
One concern with the use of SDBC in swine diets could be with potential antagonisms between branched-chain AA (Harper et al., 1984; Block, 2000). Many studies showing these antagonisms have used purified diets, whereas antagonisms between branched-chain AA have not been well illustrated in pigs receiving practical diets. In a diet composed largely of cornstarch, glucose, and sucrose, Oestemer et al. (1973) reported that increasing dietary Leu had a negative impact on plasma Ile and Val and pig performance, but there were no interactions between Ile and Leu on pig performance or protein efficiency ratio. In a semipurified diet, Henry et al. (1976) reported that increasing the Leu:Ile ratio from 1.7 to 3.0 had no effect on pig performance, even though plasma Ile and Val were affected. Using a barley-based diet, Taylor et al. (1984, 1985) suggested that a Leu:Ile ratio of 4.0 had no detrimental effect on pig performance, even at low-Ile levels. At higher levels of Ile, a Leu:Ile ratio of 4.5 was without effect. Recently, Langer and Fuller (2000) confirmed in a purified diet that excess Leu decreased N retention in an Ile-limiting diet but had no effect in an Ile-adequate diet. In Exp. 2 and 3, the reduction in performance noted by supplementing 5.0% SDBC is most likely due to an Ile deficiency, as the Leu:Ile ratio was approximately 3.2. At higher levels of SDBC supplementation, the Leu:Ile ratio of 4.3 and 6.0 in the 7.5 and 9.5% SDBC diets, respectively, suggest that some branched-chain AA antagonism may have contributed to the decreased pig performance. This potential may have been more in the diet containing 9.5% SDBC because not only was the Leu:Ile ratio being 6.0, but the level of dietary Ile was approximately 60% of the estimated NRC (1998) recommendation. However, because higher levels of Val may alleviate some of the Leu-Ile antagonisms (Harper et al., 1970), the fact that SDBC are extremely high in Val suggests that a diet containing 9.5% SDBC may not be as susceptible to the Leu:Ile antagonism as expected. The fact that our diets consisted of nonpurified ingredients and that the levels of Ile and Val were not exorbitantly elevated suggests that the use of SDBC is not likely to antagonize the utilization of Ile in nursery pigs.
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Implications
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The results of these experiments clearly indicate that spray-dried red blood cells can be supplemented at relatively high levels in nursery diets with no adverse effects on pig performance, provided that the requirement for isoleucine is met. These data also support the use of spray-dried blood cells as an excellent ingredient from which to evaluate isoleucine requirements and isoleucine:lysine ratios in nursery pigs.
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Footnotes
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1 Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply approval to the exclusion of other products that may be suitable. Appreciation is given to APC Inc. and BioKyowa Inc. for funding of this research. 
2 Correspondence: USDA-ARS-MWA-SOMMRU, National Swine Research and Information Center, NSRIC-2167, Ames, IA 50011-3310 (phone: 515-294-0224; fax: 515-294-1209; e-mail: kerr{at}nsric.ars.usda.gov).
Received for publication November 19, 2003.
Accepted for publication April 22, 2004.
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Abstract
Introduction
