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J. Anim. Sci. 2003. 81:191-196
© 2003 American Society of Animal Science

Effect of chromium propionate and metabolizable energy on growth, carcass traits, and pork quality of growing-finishing pigs1,2,3

J. O. Matthews*,4, A. D. Higbie*, L. L. Southern*,5, D. F. Coombs*, T. D. Bidner* and R. L. Odgaard{dagger}

* Department of Animal Sciences, Louisiana State University Agricultural Center, Baton Rouge, 70803 and and {dagger} Kemin Industries, Inc., Des Moines, IA 50301

5 Correspondence:
204 J. B. Francioni Bldg. (phone: 225-578-3449; fax: 225-578-3604; E-mail:
lsouthern{at}agctr.lsu.edu).


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 Implications
 Literature Cited
 
An experiment was conducted to evaluate the dietary effects of Cr propionate (CrProp) and metabolizable energy (ME) on growth, carcass traits, and pork quality of growing-finishing pigs. One hundred forty-four Cambrough-22 barrows were allotted to four dietary treatments in a randomized complete block design (six replicates of six pigs per replicate; average initial and final body weight were 27 and 113 kg, respectively). The dietary treatments were: 1) corn–soybean meal basal (B; low ME), 2) B + 200 ppb of Cr (as CrProp), 3) B + 200 kcal ME/kg (4.5% added fat; high ME), or 4) B + 200 kcal ME/kg + 200 ppb of Cr. At trial termination, three pigs per replicate were killed to determine dietary effects on carcass traits and pork quality. Overall average daily gain, average daily feed intake, and gain:feed ratio were not affected (P > 0.10) by diet. During the early growing period, average daily gain was increased in pigs fed the CrProp–low-ME diets, but decreased in pigs fed the CrProp-high ME diets (Cr x ME, P < 0.04). Feed intake was increased (P < 0.05) in pigs fed the high-ME diets during the early growing period. Forty-five min and 24 h pH were not affected (P > 0.10) by diet. The CIE L* tended (P = 0.07) to be increased and shear force tended (P = 0.06) to be decreased in pigs fed high-ME diets. Subjective marbling was increased (P < 0.03) and longissimus muscle percentage moisture and thaw loss were decreased (P < 0.04) in pigs fed CrProp. Chromium propionate had no consistent effect on growth and carcass traits in this experiment; however, CrProp did affect some aspects of pork quality.

Key Words: Chromium • Metabolizable Energy • Pigs • Pork • Propionic Acid • Quality


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 Implications
 Literature Cited
 
Research has indicated that dietary fat content may affect the response to Cr, with rats being more responsive to Cr in a high-fat diet (Striffler et al., 1995). Research specifically addressing Cr and its potential interaction with dietary fat (or energy levels) in pigs is limited, but van de Ligt et al. (1998) reported that Cr picolinate (CrPic) had no effect on growth or carcass traits and no interactions between Cr and dietary energy concentration were observed in pigs fed energy-deficient diets.

Moreover, limited research is available addressing the effects of Cr on pork quality. Page et al. (1992) and Boleman et al. (1995) reported no effects of CrPic on water-holding capacity or sensory evaluation in pigs. However, Boleman et al. (1995) reported that shear force was increased in pigs fed CrPic during the growing-finishing period compared to pigs fed CrPic during the finishing period only. O’Quinn et al. (1998) reported that CrPic decreased drip loss and marbling, and that Cr nicotinate decreased loin muscle subjective color and saturation index in gilts.

Furthermore, Matthews et al. (2001b) reported that glucose clearance was increased and glucose half-life was decreased during an insulin challenge test in pigs fed Cr propionate (CrProp), indicating that CrProp is a bioavailable source of Cr. Thus, the purpose of this experiment was to evaluate the effects of CrProp and dietary ME (added fat) on growth, carcass traits, and pork quality of growing-finishing pigs.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 Implications
 Literature Cited
 
The procedures used in this experiment were approved by the Louisiana State University Agricultural Center Institutional Animal Care and Use Committee.

General

One hundred forty-four PIC Cambrough-22 barrows were allotted based on weight to four dietary treatments in a randomized complete block design. Each treatment consisted of six replicates of six pigs per replicate with an initial mean BW of 27 kg. A four-phase grower-finisher program was used with diets formulated to provide 1.13, 0.89, 0.82, and 0.74% lysine for weight ranges of 27 to 43, 43 to 71, 71 to 99, and 99 to 117 kg, respectively. Total sulfur amino acids, tryptophan and threonine were formulated to meet the minimal ideal ratio of Baker (1994), and all other nutrients met or exceeded NRC (1998) requirements. Dietary treatments included: 1) corn–soybean meal diet (basal; Table 1Go), 2) basal + 200 ppb of Cr as CrProp (KemTRACE Chromium; Kemin Industries, Inc., Des Moines, IA), 3) basal + 200 kcal ME/kg diet (4.5% added fat), or 4) basal + 200 kcal ME/kg diet + 200 ppb of Cr as CrProp. Treatment diets and water were provided for ad libitum consumption. Pigs were housed in an open-sided finishing barn in 1.52 x 4.27 m pens with aluminum slat (1.52 x 2.44 m) and solid concrete (1.52 x 1.83 m) floors. Pigs and feeders were weighed every 2 wk for calculation of ADG, ADFI, and feed efficiency. The experimental period lasted 93 d.


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  		Table 1. Composition of basal diets (as-fed basis)
 
Plasma Collection and Analyses

Blood samples from pigs fasted for 16 h were collected via the anterior vena cava on d 23 (late grower), 56 (early finisher), and 83 (late finisher) of the experiment. After collection of blood, the samples were placed on ice for 2 h, and then centrifuged for 15 min at 1,500 x g at 4°C. Plasma was collected and frozen (-20°C) until subsequent analysis for NEFA concentrations. Nonesterified fatty acid concentrations were determined by an enzymatic colorimetric procedure (NEFA-C Kit, ACS-ACOD Method; Wako Chemicals USA, Richmond, VA) as described by McCutcheon and Bauman (1986).

Carcass and Pork Quality Evaluation

At the end of the growth trial (average BW = 113 kg), three pigs from each replicate were randomly selected for slaughter. Pigs were slaughtered in two groups (three weight blocks per slaughter group). Although the growth trial had ended, pigs from the second slaughter group remained on treatment diets until slaughter. Pigs (average slaughter BW = 117 kg) were transported to the Louisiana State University Agricultural Center Meats Laboratory for slaughter. Pigs were killed by electrical stunning followed by exsanguination. Conventional carcass, total body electrical conductivity, and pork quality data were determined on the left carcass side as described by Matthews et al. (2001c). Percentage of muscling and kilograms of lean were calculated using the equations described by NPPC (1991), which uses a 5% estimation for intramuscular fat and compensates for unequal body weights.

Statistical Analysis

Data were analyzed by ANOVA (Steel and Torrie, 1980) using the GLM procedure of SAS (SAS Inst., Inc., Cary, NC) as a randomized complete block design. The pen of pigs served as the experimental unit for all data. Orthogonal single degree-of-freedom contrasts were used to determine the main effects of Cr and ME and the interaction between Cr and ME. Effects were considered significant at P < 0.05. Probability values of P > 0.05 and P < 0.10 were considered trends and probability values of P > 0.10 were considered not significant.


   Results
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 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 Implications
 Literature Cited
 
During the early grower period, the high-ME diet increased ADFI (P < 0.05; Table 2Go), but ADG was not affected (P > 0.10), resulting in a numerical decrease in gain:feed. During the late-grower, early-finisher, late-finisher, and overall periods, the ME level of the diet did not affect (P > 0.10) ADG, ADFI, gain:feed, or plasma NEFA concentrations.


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  		Table 2. Effect of chromium propionate and metabolizable energy on growth performancea
 
During the early grower period, ADG was increased in pigs fed CrProp in low-ME diets, but decreased in pigs fed CrProp in high-ME diets (Cr x ME, P < 0.04). Otherwise, ADG, ADFI, gain:feed ratio, or plasma NEFA concentrations during the early-grower, late-grower, early-finisher, late-finisher, and overall periods were not affected (P > 0.10). Furthermore, carcass characteristics were not affected by ME level of the diet or by the addition of CrProp (P > 0.10; Table 3Go).


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  		Table 3. Effect of chromium propionate and metabolizable energy on carcass characteristicsa
 
Forty-five–min carcass temperature and Commission Internationale de l’Eclairage (CIE) L* tended (P = 0.07) to be increased in pigs fed high-ME diets, but shear force (P = 0.06) tended to be decreased in pigs fed high-ME diets (Table 4Go). Subjective marbling was increased (P < 0.03) in pigs fed CrProp. Percentage of moisture in the loin muscle and thaw loss were decreased (P < 0.04) in pigs fed CrProp. No other measure of pork quality was affected (P > 0.10) by CrProp and no other interactions were observed (P > 0.10).


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  		Table 4. Effect of chromium propionate and metabolizable energy on pork qualitya
 

   Discussion
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 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
Implications
 Literature Cited
 
The effects of CrProp on growth and carcass traits were minimal. Matthews et al. (2001b) reported that CrProp decreased ADFI by 8.8% during the late-finisher period. In the present study, feed intake was only numerically decreased during the late-finisher period. Although some reports have indicated that CrPic may improve ADG and feed efficiency (Lindemann et al., 1995; Mooney and Cromwell, 1995), other researchers have indicated that CrPic does not affect growth performance (Evock-Clover et al., 1993; Mooney and Cromwell, 1999), and our data with CrProp are generally in agreement with those reports indicating CrPic does not affect growth performance. However, daily gain during the early-grower period was increased in pigs fed CrProp in low-ME diets, but decreased in pigs fed CrProp in high-ME diets. Research has indicated that Cr deficiency may be exacerbated by the addition of fat (40% lard) to the diet of rats (Striffler et al., 1995). Although the level of fat in our diets was much lower (4.5%), this may explain the occurrence of this effect on ADG during the early-grower period, but does not explain the lack of this effect during the other periods. Moreover, van de Ligt et al. (1998) reported no interactive effects of CrPic and dietary energy level; however, all energy levels used were below requirements.

Plasma NEFA concentrations were not affected in pigs fed CrProp. Matthews et al. (2001b) reported that plasma NEFA concentrations were decreased or tended to be decreased in pigs fed CrPic or CrProp in a diet without added fat, but we are unaware of reports indicating that Cr affects plasma or serum NEFA concentrations in pigs fed high-fat diets.

Reports also have indicated that CrPic increases carcass leanness in pigs (Page et al., 1993; Lindemann et al., 1995; Mooney and Cromwell, 1995), and Matthews et al. (2001b) reported that CrProp tended to increase percentage of muscling in pigs. Other reports have indicated that CrPic does not affect carcass leanness (Evock-Clover et al., 1993; Mooney and Cromwell, 1999) and our data agree.

Page et al. (1992) reported that CrPic did not affect water-holding capacity (drip or cooking loss) or shear force of chops from the loin muscle. However, some research has indicated that Cr may affect pork quality. Boleman et al. (1995) reported no effects of CrPic on water-holding or sensory evaluation in the loin muscle of pigs, but shear force was increased in pigs fed CrPic throughout the growing-finishing period compared to pigs fed CrPic during the finishing period only. O’Quinn et al. (1998) reported that CrPic decreased drip loss and marbling, and that Cr nicotinate decreased loin muscle subjective color and saturation index in gilts. Our data are partially in agreement with O’Quinn et al. (1998) in that thaw loss was decreased in pigs fed CrProp, but our data indicate that subjective marbling score was increased by CrProp. Although our data did not objectively measure marbling, the reduction in percentage of moisture may give some confirmation of the subjective marbling scores because an increase in intramuscular fat should be inversely related to moisture content.

Two possible mechanisms for Cr to affect pork quality include: 1) the effect of Cr on carbohydrate metabolism, or 2) the effect of Cr on stress. Research has indicated that CrProp or CrPic increases insulin sensitivity as assessed by increased glucose clearance during an intravenous insulin challenge test (Amoikon et al., 1995; Matthews et al., 2001b). In vitro research has indicated that CrPic decreases insulin binding in porcine hepatic tissue, but CrPic increases insulin binding in porcine red blood cell ghosts and adipocytes (Ward et al., 1994; Berrio et al., 1995). This response indicates that Cr may enhance insulin binding in certain tissues, resulting in improved glucose uptake by these tissues, but may decrease insulin binding in other tissues. Although we are unaware of research indicating that Cr may increase or decrease glucose uptake in swine muscle tissue, the aforementioned research would indicate that Cr might affect glucose uptake (glycolytic potential) in muscle tissues and subsequently affect pork quality.

Research has consistently indicated that preslaughter stress affects pork quality. Some preslaughter factors that affect stress include rest time at the lairage, mixing unfamiliar pigs, transportation length, and handling procedures implemented when moving pigs (Jones et al., 1994; Matthews et al., 2001a). Generally, these stresses are considered short-term stresses. Ward et al. (1997) reported that CrPic supplementation in pigs did not alleviate the stress associated with crowding. Matthews et al. (2001a) reported that pigs may adjust to the long-term stress of crowding and subsequently be less affected by short-term stressors, such as those encountered at slaughter. Thus, in the research of Ward et al. (1997), the use of crowding stress may have been inappropriate to test the effects of CrPic on stress if the pigs adjusted to the crowding stress. Some research has indicated that Cr may partially alleviate the effects of a short-term stress, such as shipping stress in feedlot calves (NRC, 1997). Furthermore, other reports have indicated that Cr may decrease serum cortisol levels in calves (Mowat et al., 1993).


   Implications
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Implications
Literature Cited
 
The improvements observed for certain aspects of pork quality in pigs fed chromium propionate may be of importance to the swine industry. However, more research is necessary to determine the consistency in which chromium propionate may improve pork quality. Furthermore, these data indicate that chromium propionate is a potential organic source of chromium.


   Footnotes
 
1 Approved for publication by the Director of the Louisiana Agric. Exp. Stn. as Pub. No. 02-18-0770. Back

2 The authors would like to thank the Louisiana State Univ. Agric. Center Meats Laboratory for assistance with data collection. The authors also would like to thank L. Camp, A. Guzik, L. Johnston, R. Payne, E. Shelton, and J. Shelton for assistance with data collection and sample analyses. Back

3 Research supported in part by Kemin Industries, Des Moines, IA. Back

4 Current address: Premium Standard Farms, 22123 Highway 5, P.O. Box 99, Milan, MO 63556. Back

Received for publication December 16, 2001. Accepted for publication September 3, 2002.


   Literature Cited
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 Implications
 Literature Cited
 


Amoikon, E. K., J. M. Fernandez, L. L. Southern, D. L. Thompson Jr., T. L. Ward, and B. M. Olcott. 1995. Effect of chromium tripicolinate on growth, glucose tolerance, insulin sensitivity, plasma metabolites, and growth hormone in pigs. J. Anim. Sci. 73:1123–1130.[Abstract]

Baker, D. H. 1994. Ideal protein for pigs. Page 235 in Proc. Minnesota Nutr. Conf., St. Paul.

Berrio, L. F., L. L. Southern, J. M. Fernandez, D. L. Thompson Jr., and T. L. Ward. 1995. Effect of dietary chromium tripicolinate on insulin binding in isolated pig fat cells and erythrocyte ghosts. FASEB J. 9:A449.

Boleman, S. L., S. J. Boleman, T. D. Bidner, L. L. Southern, T. L. Ward, J. E. Pontif, and M. M. Pike. 1995. Effect of chromium picolinate on growth, body composition, and tissue accretion in pigs. J. Anim. Sci. 73:2033–2042.[Abstract]

Evock-Clover, C. M., M. M. Polansky, R. A. Anderson, and N. C. Steele. 1993. Dietary chromium supplementation with or without somatotropin treatment alters serum hormones and metabolites in growing pigs without affecting growth performance. J. Nutr. 123:1504–1512.

Jones, S. D. M., R. L. Cliplef, A. F. Fortin, R. M. McKay, A. C. Murray, S. A. Pommier, A. P. Sather, and A. L. Schaefer. 1994. Production and ante-mortem factors influencing pork quality. Pig News Info. 15:15N–18N.

Lindemann, M. D., C. M. Wood, A. F. Harper, E. T. Kornegay, and R. A. Anderson. 1995. Dietary chromium picolinate additions improve gain:feed and carcass characteristics in growing-finishing pigs and increase litter size in reproducing sows. J. Anim. Sci. 73:457–465.[Abstract]

Matthews, J. O., L. L. Southern, T. D. Bidner, and M. A. Persica. 2001a. Effects of betaine, pen spacing, and slaughter handling method on growth performance, carcass traits, and pork quality of finishing barrows. J. Anim. Sci. 79:967–974.[Abstract/Free Full Text]

Matthews, J. O., L. L. Southern, J. M. Fernandez, J. E. Pontif, T. D. Bidner, and R. L. Odgaard. 2001b. Effect of chromium picolinate and chromium propionate on glucose and insulin kinetics of growing barrows and on growth and carcass traits of growing-finishing barrows. J. Anim. Sci. 79:2172–2178.[Abstract/Free Full Text]

Matthews, J. O., L. L. Southern, A. D. Higbie, M. A. Persica, and T. D. Bidner. 2001c. Effects of betaine on growth, carcass characteristics, pork quality, and plasma metabolites of finishing pigs. J. Anim. Sci. 79:722–728.[Abstract/Free Full Text]

McCutcheon, S. N., and D. E. Bauman. 1986. Effect of chronic growth hormone treatment on responses to epinephrine and thyrotropin-releasing hormone in lactating cows. J. Dairy Sci. 69:44–51.

Mooney, K. W., and G. L. Cromwell. 1995. Effects of dietary chromium picolinate supplementation on growth, carcass characteristics, and accretion rates of carcass tissues in growing-finishing swine. J. Anim. Sci. 73:3351–3357.[Abstract]

Mooney, K. W., and G. L. Cromwell. 1999. Efficacy of chromium picolinate on performance and tissue accretion in pigs with different lean gain potential. J. Anim. Sci. 77:1188–1198.[Abstract/Free Full Text]

Mowat, D. N., X. Chang, and W. Z. Yang. 1993. Chelated chromium for stressed feeder calves. Can. J. Anim. Sci. 73:49–55.

NPPC. 1991. Procedures to Evaluate Market Hogs. 3rd ed. Natl. Pork Prod. Council, Des Moines, IA.

NRC. 1997. The Role of Chromium in Animal Nutrition. Natl. Acad. Press, Washington, DC.

NRC. 1998. Nutrient Requirements of Swine. 10th ed. 1998. Natl. Acad. Press, Washington, DC.

O’Quinn, P. R., J. W. Smith II, J. L. Nelssen, M. D. Tokach, R. D. Goodband, and K. Q. Owen. 1998. Effects of source and level of added chromium on growth performance and carcass characteristics of growing-finishing pigs. J. Anim. Sci. 76(Suppl. 2):56. (Abstr.)

Page, T. G., S. L. Boleman, M. M. Pike, T. L. Ward, S. J. Boleman, L. L. Southern, T. D. Bidner, and J. E. Pontif. 1992. Effect of chromium picolinate on carcass traits and aging on pork quality. J. Anim. Sci. 70(Suppl. 1):218. (Abstr.)

Page, T. G., L. L. Southern, T. L. Ward, and D. L. Thompson Jr. 1993. Effect of chromium picolinate on growth and serum and carcass traits of growing-finishing pigs. J. Anim. Sci. 71:656–662.[Abstract]

Steel, R. G. D., and J. H. Torrie. 1980. Principles and Procedures of Statistics: A Biometrical Approach. 2nd ed. McGraw-Hill Publishing Co., New York.

Striffler, J. S., M. M. Polansky, O. E. Michaelis IV, and R. A. Anderson. 1995. Expression of chromium-deficiency in rats may be related to dietary fat content. FASEB J. 9:A449. (Abstr.)

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