424 The Professional Animal Spears Scientist et al. 19 (2003):

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1 424 The Professional Animal Spears Scientist et al. 19 (2003): E ffects of High Dietary Calcium Propionate and Dietary Cation- Anion Balance on Calcium Metabolism and Longissimus Muscle Tenderness in Finishing Steers 1, 2 J. W. SPEARS *,3, PAS, T. E. ENGLE, PAS, W. R. PLATTER, K. E. LLOYD *, K. E. BELK, and J. HORTON,4, PAS * Department of Animal Science, North Carolina State University, Raleigh ; Department of Animal Science, Colorado State University, Fort Collins ; and Kemin Americas, Des Moines, IA Abstract Forty-eight Angus and Angus-cross steers (initial BW = 657 ± 5.7 kg) were used in a 2 2 factorial design to determine whether feeding an anionic diet or high dietary concentrations of a soluble calcium (Ca propionate) source or both would alter Ca metabolism and subsequently longissimus tenderness. s consisted of 1) control, 2) 4% Ca propionate (CaProp), 3) 2% NH 4 1 Use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service or criticism of similar products not mentioned. 2 This research was supported in part by a gift from Kemin Americas, Des Moines, IA. 3 To whom correspondence should be addressed: Jerry_Spears@ncsu.edu 4 Present address: Nutrition Service Associates, P. O. Box 350, Hereford, TX (anionic diet), and 4) CaProp plus 2% NH 4. Experimental diets were fed for 7 d prior to slaughter. Steers were individually fed using electronic Calan gate feeders. Blood samples were obtained on d 3 and 7 at 2 h post feeding for plasma Ca determination. A striploin steak was obtained from each carcass at 48 h post harvest for muscle Ca analysis and Warner-Bratzler shear force (WBSF) determination. Addition of CaProp or NH 4 to the high concentrate finishing diet reduced (P<0.01) ADG and DMI during the 7-d feeding period. The anionic diet reduced ADG to a greater extent than did CaProp. Average daily gain and DMI were lowest for steers fed both NH 4 and CaProp, indicating that their effects were additive. Carcass characteristics were not affected by CaProp, but the anionic diet tended to reduce hot carcass weights (P=0.13) and longissimus areas (P=0.09). Plasma Ca concentrations were slightly greater in steers fed CaProp on d 3 (P<0.10) and 7 (P<0.01) of the study. The anionic diet did not affect plasma Ca. Muscle Ca concentrations and WBSF values were not affected by either CaProp or the anionic diet. Results indicate that beef tenderness was not enhanced in steers fed a diet high in CaProp or those fed an anionic diet. (Key Words: Calcium, Anionic Diet, Beef Tenderness, Steers.) Introduction Calcium in muscle activates both µ-calpain and m-calpain, which are involved in the post-mortem tenderization process (Koohmaraie, 1992). Increasing post-mortem muscle Ca concentrations by injecting a Ca 2 solution into beef enhances meat tenderness (Wheeler et al., 1992). Recently, there has been interest in nutritional approaches to improve beef tenderness by increasing plasma and muscle Ca concentrations immediately prior to slaughter.

2 Dietary Calcium and Anionic Diet Effects on Beef Tenderness 425 Supplementation with high levels of vitamin D for 7 d prior to slaughter increased plasma and muscle Ca in finishing cattle (Swanek et al., 1999). Beef tenderness has been improved by vitamin D supplementation in some studies (Montgomery et al., 2000, 2002; Swanek et al., 1999) but not in others (Scanga et al., 2001). Blood Ca concentrations are generally tightly regulated. However, high concentrations of certain Ca sources, which are soluble even at a neutral ph, may increase plasma Ca concentrations via enhanced paracellular absorption of Ca. Calcium absorption from the small intestine occurs by both active and paracellular absorption. The paracellular route of Ca absorption becomes more important when dietary Ca is high. The amount of Ca absorbed by the paracellular route is directly related to soluble Ca concentrations in the intestinal lumen (Bronner, 1998). Studies with sheep or with ruminal epithelial tissue obtained from sheep have indicated that Ca can be absorbed from the rumen if soluble Ca concentrations are high (Care et al., 1984; Holler et al., 1988). Calcium sources that are relatively insoluble at slightly acidic ph may result in less absorption from the rumen, intestine, or both than more soluble Ca sources. In support of this hypothesis, oral administration of large doses of Ca from Ca propionate or Ca 2 increased plasma Ca concentrations in dairy cows, but CaCO 3 did not (Goff and Horst, 1993). Ruminal soluble concentrations of Ca were also over 34 times greater in steers fed Ca propionate than in steers fed CaCO 3 when Ca was supplemented to diets at 0.66% (Spears et al., 2002). An anionic diet prior to slaughter may increase Ca absorption from the diet or increase Ca mobilization from bone, or both, thus, increasing Ca concentrations in muscle. Anionic salts have been widely used in prepartum dairy cow diets to reduce dietary cation-anion balance (DCAB). A negative DCAB diet fed to dairy cows during the prepartum period increases plasma Ca concentrations around parturition and reduces the incidence of milk fever (Block, 1984). An anionic diet causes a mild metabolic acidosis that increases Ca absorption from the gut (Schonewille et al., 1994) and may increase mobilization of Ca from bone (Block, 1984). The present study was conducted to determine the effects of an anionic diet, a diet high in soluble Ca (Ca propionate), or both for 7 d prior to slaughter on performance, Ca metabolism, and longissimus tenderness. Materials and Methods Care, handling, and sampling of the animals used in this study were approved by the North Carolina State University Animal Care and Use Committee. Forty-eight Angus and Angus-cross steers, with an average initial BW of 657 ± 5.7 kg, were randomly assigned to one of four treatments. s consisted of 1) control, 2) 4% Ca propionate (CaProp), 3) 2% NH 4, and 4) 4% CaProp plus 2% NH 4. Levels of CaProp and NH 4 were based on preliminary studies conducted to determine the maximum dose of each that could be fed with minimal effect on feed intake. Prior to initiation of the study, steers had been fed a high concentrate diet for over 100 d. Steers on the control treatment received a diet (as-fed basis) consisting of 30% corn silage and 70% of the concentrate mix shown in Table 1. Calcium propionate and NH 4 were added on an as-fed basis at the expense of the concentrate mix. Analyzed mineral content and DCAB of the diets are presented in Table 2. The DCAB was calculated using the equation: meq of (Na + K) meq of /100 g of DM. Steers were housed in groups of 12 in covered, slotted floor pens and individually fed using electronic Calan gate feeders (American Calan, Northwood, NH). Steers were fed using the Calan gates for over 100 d prior to initiation of dietary treatments. Experimental diets were fed for 7 d prior to slaughter. Diets were fed twice a day, and feed offerings for each steer were restricted to approximately 80% of ad libitum intake for the previous 7 d. Feed intake was restricted to encourage steers to consume a large meal that would supply sufficient Ca from CaProp to elevate soluble Ca concentrations in digesta. Elevated soluble Ca should enhance paracellular absorption of Ca. Steers were weighed on 2 consecutive d at the beginning and end of the study. Jugular blood samples were obtained on d 3 and 7 at 2 h post feeding for plasma Ca determination. Steers were slaughtered at a commercial abattoir, and hot carcass weights were obtained on the day of harvest. Other carcass measurements were taken 48 h after slaughter by a certified USDA grader. After collection of carcass data, a striploin (2.5 cm thickness) was removed from each carcass. A sample of the striploin was frozen and later used for determination of water-extractable Ca. Striploin steaks were individually packaged in whirl-pak bags (Nasco, Fort Atkinson, WI), frozen, and then shipped to the Colorado State University meat laboratory for Warner- TABLE 1. Composition of basal concentrate mix. Item (% DM) Corn, ground 90.7 Soybean meal 6.3 Urea 0.79 CaCO K 0.40 CaSO Trace mineral salt 0.53 Vitamins A, D, and E a 0.01 Rumensin b + a Contained (/kg of premix): 26,431,000 IU of vitamin A, 8,810,000 IU of vitamin D 3, and 44,000 IU of vitamin E. b Provided 30 mg monensin/kg DM.

3 426 Spears et al. TABLE 2. Analyzed mineral content of complete diets. Bratzler shear force (WBSF) determination. On arrival at Colorado State, the steaks were vacuum-packed and then aged for 14 d prior to WBSF measurements. Frozen steaks were thawed at 2ºC for 24 h and cooked approximately 15 min on an electric grill (Model GGR64; Salton, Inc., Mt. Prospect, IL) that heated steaks from both sides, simultaneously, to a final internal temperature of 70ºC. A Type K thermocouple (Omega Engineering Inc., Stamford, CT) was placed in the geometric center of each steak, and the internal temperature of each steak was monitored during cooking using a microprocessor thermometer (Model HH21; Omega Engineering Inc.). After cooking, each steak was allowed to equilibrate to room temperature (22ºC), and six to 10 cores (1.27 cm diameter) were removed from each steak parallel to the muscle fiber orientation using a Warner-Bratzler sheer machine (G-R Electric Manufacturing Co., Manhattan, KS). Peak sheer force measurements were recorded and averaged to obtain a single WBSF value for each steak. Water-extractable Ca in muscle was measured using the procedures described by Nakamura (1973). After extraction, Ca was measured by atomic absorption spectroscopy (Model AA-6701 F; Shimadzu, Kyoto, Japan). Diets were prepared for Ca, 4% Ca Propionate Ca Prop Item Control (Ca Prop) 2% NH 4 + 2% NH 4 Ca, % Na, % K, % , % S, % DCAB a, meq/100 g DM a DCAB = Dietary cation-anion balance. Calculated using the equation: meq (Na + K) meq /100 g DM. Na, and K analysis by wet ashing using nitric acid and hydrogen peroxide in a microwave digester (Model MDS-81D; CEM, Matthews, NC) as described previously (Gengelbach et al., 1984). Calcium, Na, and K were determined by atomic absorption spectroscopy. Diets were analyzed for and S at the DHI Forage Testing Laboratory (Ithaca, NY). Data were statistically analyzed as a factorial using the GLM procedures of SAS (SAS Inst. Inc., Cary, NC). The model included slaughter dates (steers were slaughtered on two dates), Ca, NH 4, and Ca NH 4 interaction. Results and Discussion Supplementation with high levels of CaProp or NH 4 to create an anionic diet greatly reduced (P<0.01) ADG and DMI during the 7-d feeding period (Table 3). Reduced feed intake in steers fed CaProp probably relates to the odor or taste of the CaProp. However, heifers dosed with 75 g CaCO 3 /d in combination with high levels of vitamin D had lower gain and feed intake than did heifers only dosed with vitamin D (Scanga et al., 2001). The anionic diet reduced ADG and DMI to a greater extent than did CaProp. Finishing steers fed a diet with a DCAB of 0 had less ADG and DMI than did those fed diets with a DCAB of 15 or 30 meq/100 g DM (Ross et al, 1994). Steers fed the anionic diet alone or in combination with CaProp had less final BW than controls (Table 3). Average daily gain and DMI were least in steers fed the anionic diet and CaProp, indicating that their effects were additive. Carcass characteristics were not significantly affected by CaProp (Table 4). Steers fed the anionic diet tended to have lesser carcass weights TABLE 3. Effects of 4% calcium propionate (CaProp), an anionic diet, or both on feed intake and BW change of finishing steers. Ca Prop Item Control CaProp 2% NH 4 + 2% NH 4 SEM Initial BW, kg Final BW, kg a ADG, kg b,c Feed intake, kg DM/d 7-d Pre-treatment Post-treatment b,c Reduction, % a Anionic diet effect (P<0.05). b Anionic diet effect (P<0.01). c CaProp propionate effect (P<0.01).

4 Dietary Calcium and Anionic Diet Effects on Beef Tenderness 427 TABLE 4. Effects of 4% calcium propionate (CaProp), an anionic diet, or both on carcass characteristics of steers. (P=0.13) and longissimus areas (P=0.09) than did controls. Other carcass measurements were not affected by the anionic diet. Plasma Ca concentrations were greater in steers supplemented with CaProp on d 3 (P<0.10) and 7 (P<0.01) of the study (Table 5). However, the increase in plasma Ca relative to controls was small compared with increases in plasma Ca that have been observed in cattle fed high concentrations of vitamin D (Montgomery et al., 2002, 2002). The anionic diet did not affect plasma Ca. Muscle Ca concentrations and WBSF values were not affected by CaProp or the anionic diet (Table 6). Drenching cattle with 150 g Ca from CaProp within 35 to 125 min of slaughter tended to increase muscle Ca and improve tenderness in strip steak but not in eye round or chuck tender (Hanson et al., 2002). In the present study, Ca intake from CaProp averaged 58 and 43 g/d for steers on the CaProp and CaProp plus NH 4 treatments, respectively. The anionic diet fed for 7 d prior to slaughter did not increase plasma or muscle Ca concentrations in finishing steers. If Ca absorption or mobilization from bone was increased by the anionic 2% CaProp + Item Control CaProp NH 4 2% NH 4 SEM Hot carcass wt, kg Dressing percentage Marbling score a Quality grade b Yield grade Longissimus area, cm c Fat thickness, cm a 5 = Small, 6 = modest, and 7 = moderate. b Choice = 17, Choice o = 18, and Choice + = 19. c Anionic diet effect (P<0.10). diet, the increased Ca supply was apparently rapidly excreted in the urine. Apparent absorption of Ca was over twice as high in nonlactating dairy cows fed an anionic diet compared with those fed a normal diet (Schonewille et al., 1994); however, urinary Ca excretion was 14.5-fold greater in cows fed the anionic diet. The addition of NH 4 to sheep diets at concentrations that would result in an anionic DCAB also increased both absorption and urinary excretion of Ca (Braithwaite, 1972). Dairy cows fed an anionic diet during the prepartum period have increased plasma Ca around the time of parturition (Block, 1984; Oetzel et al., 1988) when plasma Ca concentrations are less than normal values observed in nonlactating or lactating cows. However, anionic diets have not affected plasma Ca concentrations in nonlactating dairy cows with normal plasma Ca concentrations (Schonewille et al., 1994). The present study suggests that oral feeding of CaProp to finishing steers will not increase muscle Ca and, thus, not improve beef tenderness. Reduced feed intake observed in steers supplemented with CaProp limited Ca intake from CaProp to only 58 g/d. During the 7-d experimental period, steers were fed twice daily, and the feed offered to each steer was restricted to 80% of their intake for the previous 7 d. This feeding regimen was followed in an attempt to encourage steers to consume two large meals per day that would supply sufficient Ca from CaProp to greatly elevate soluble Ca concentrations in digesta. Enhancing Ca absorption via paracellular absorption would require a high concentration of soluble Ca in the rumen, small intestine, or both. It is expected that soluble Ca concentrations in digesta are affected by the daily quantity of Ca consumed and TABLE 5. Effects of 4% calcium propionate (CaProp), an anionic diet, or both on plasma Ca concentrations of finishing steers. 2% CaProp + Plasma Ca Control CaProp NH 4 2% NH 4 SEM (mg/dl) d 3 a d 7 b a CaProp effect (P<0.10). b CaProp effect (P<0.01).

5 428 Spears et al. TABLE 6. Effects of 4% calcium propionate (CaProp), an anionic diet, or both on longissimus Ca concentrations and Warner-Bratzler shear force (WBSF) values. also the rate of Ca consumption. Oral administration of 50 g Ca from CaProp in 1 L water in nonpregnant, nonlactating dairy cows elevated plasma Ca concentrations for at least 6 h after dosing (Goff and Horst, 1993). This result suggests that a single or multiple oral doses of CaProp to finishing steers would elevate plasma Ca and perhaps muscle Ca to the extent needed to alter muscle tenderness, if administered at the appropriate time prior to slaughter. Implications Increasing tenderness of beef would likely increase consumer demand for beef. Therefore, there is considerable interest in dietary approaches that may improve beef tenderness. An anionic diet fed to steers during the last 7 d of finishing did not alter plasma or muscle Ca concentrations or striploin steak tenderness. Furthermore, the anionic diet greatly reduced feed intake. Feeding a diet high in Ca propionate, a soluble Ca source, also failed to improve striploin tenderness. Supplementing Ca propionate slightly increased plasma Ca but not muscle Ca concentrations. Reduced feed intake in steers fed high dietary CaProp + Item Control CaProp 2% NH 4 2% NH 4 SEM Muscle Ca, mg/kg Shear force, kg Ca propionate limited Ca intake. Further studies are needed to determine whether oral administration of large doses of Ca propionate prior to harvest can increase beef tenderness. Literature Cited Block, E Manipulating dietary anions and cations for prepartum dairy cows to reduce incidence of milk fever. J. Dairy Sci. 67:2939. Braithwaite, G. D The effect of ammonium chloride on calcium metabolism in sheep. Br. J. Nutr. 27:201. Bronner, F Calcium absorption A paradigm for mineral absorption. J. Nutr. 128:917. Care, A. D., R. C. Brown, A. R. Farrar, and D. W. Pickard Magnesium absorption from the digestive tract of sheep. Q. J. Exp. Physiol. 69:577. Gengelbach, G. P., J. D. Ward, and J. W. Spears Effect of dietary copper, iron, and molybdenum on growth and copper status of beef cows and calves. J. Anim. Sci. 72:2722. Goff, J. P., and R. L. Horst Oral administration of calcium salts for treatment of hypocalcemia in cattle. J. Dairy Sci. 76:101. Hanson, D., C. Calkins, and J. Horton Oral dosage with NutroCal (calcium propionate) to enhance beef tenderness. In 2002 Nebraska Beef Cattle Report. p 87. Dep. Anim. Sci., Univ. Nebraska, Lincoln. Holler, H., G. Breves, M. Kocabatmaz, and H. Gerdes Flux of calcium across the sheep rumen wall in vivo and in vitro. Q. J. Exp. Physiol. 73:609. Koohmaraie, M The role of Ca +2 - dependent proteases (calpains) in postmortem proteolysis and meat tenderness. Biochimie 74:239. Montgomery, J. L., F. C. Parrish, D. C. Beitz, R. L. Horst, E. J. Huff-Lonergan, and A. H. Trendle The use of vitamin D 3 to improve beef tenderness. J. Anim. Sci. 78:2615. Montgomery, J. L., M. A. Carr., C. R. Kerth, G. G. Hilton, B. P. Price, M. L. Galyean, R. L. Horst, and M. F. Miller Effect of vitamin D 3 supplementation level on the postmortem tenderization of beef from steers. J. Anim. Sci. 80:971. Nakamura, R Estimation of waterextractable Ca in chicken breast muscle by atomic absorption. Anal. Biochem. 53:531. Oetzel, G. R., J. D. Olson, C. R. Curtis, and M. J. Fettman Ammonium chloride and ammonium sulfate for prevention of parturient paresis in dairy cows. J. Dairy Sci. 71:3302. Ross, J. G., J. W. Spears, and J. D. Garlich Dietary electrolyte balance effects on performance and metabolic characteristics in finishing steers. J. Anim. Sci. 72:1600. Scanga, J. A., K. E. Belk, J. D. Tatum, and G. C. Smith Supranutritional oral supplementation with vitamin D 3 and calcium and the effects on beef tenderness. J. Anim. Sci. 79:912. Schonewille, J. T., A. T. Van t Klooster, A. Dirkzwager, and A. C. Beynen Stimulatory effect of an anion (chloride)-rich ration on apparent calcium absorption in dairy cows. Livest. Prod. Sci. 40:233. Spears J. W., V. Fellner, and F. R. Valdez Comparative metabolism of calcium from calcium carbonate and calcium propionate in growing steers. J. Anim. Sci. 80(Suppl. 1): 366 (Abs.). Swanek, S. S., J. B. Morgan, F. N. Owens, D. R. Gill, C. A. Strasia, H. G. Dolezal, and F. K. Ray Vitamin D 3 supplementation of beef steers increases longissimus tenderness. J. Anim. Sci. 77:874. Wheeler, T. L., M. Koohmaraie, J. L. Lansdell, G. R. Siragusa, and M. F. Miller Effects of postmortem injection time, injection level, and concentration of calcium chloride on beef quality traits. J. Anim. Sci. 71:2965.