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Effect of ammonium sulfate fertilization on bahiagrass quality and copper metabolism in grazing beef cattle^1,2

J. D. Arthington^*,3, J. E. Rechcigl^*,4, G. P. Yost, L. R. McDowell and M. D. Fanning^,5

^* University of Florida, Range Cattle Research and Education Center, Ona 33865 and and Department of Animal Sciences, Gainesville 32611 and and Southwest Florida Research and Education Center, Immokalee 34142

² Correspondence:
3401 Experiment Station (phone: 863-735-1314, fax: 863-735-1930; E-mail:
jdarthington{at}mail.ifas.ufl.edu).

	Abstract

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To assess the impact of S fertilization on bahiagrass (Paspalum notatum) quality and Cu metabolism in cattle, two studies were conducted during the summer grazing season (1999 and 2000). Pasture replicates (16.2 ha; n = 2/treatment) received the same fertilizer treatment in each growing season, consisting of 1) 67 kg N/ha from ammonium sulfate (AS), 2) 67 kg N/ha from ammonium nitrate (AN), and 3) control (no fertilizer; C). Forage sampling was conducted at 28-d intervals following fertilization by the collection of whole plants (four samples/pasture) in randomly distributed 1-m² grazing exclusion cages and analyzed for CP, in vitro organic matter digestibility, S, P, Ca, K, Mg, Na, Fe, Al, Mn, Cu, and Zn. To determine the effect of fertilizer treatment on liver trace mineral concentrations in grazing cattle, random liver tissue samples were collected (n = 12; four/treatment) at the start and end of the study period in 2000. Ammonium sulfate fertilization increased (P < 0.001) forage S concentration in both years. Plant tissue N concentrations were increased by N fertilization, regardless of source, in 2000, but not in 1999. Cows grazing AS pastures had lower (P < 0.05) liver Cu concentrations at the end of the study period in 2000 compared to AN and C. In Exp. 2, 37 Cu-deficient heifers grazing AS fertilized pastures were obtained from the same location and allocated to one of two treatments, consisting of supplements providing 123 mg/d of either inorganic (Cu sulfate; n = 12) or organic (Availa-Cu; n = 15) Cu. Treatments were delivered for 83 d. Liver Cu increased over time in all heifers regardless of treatment; however, heifers supplemented with Availa-Cu tended (P = 0.09) to have higher mean liver Cu concentrations than those receiving Cu sulfate. The results of these studies indicate that AS fertilization of bahiagrass increases forage S concentrations. When provided free-choice access to a complete salt-based trace mineral supplement, cows grazing AS-fertilized pastures had lower liver Cu concentrations than cows grazing pastures fertilized with AN; upon removal from high-S pastures, cattle were able to respond to Cu supplementation.

Key Words: Cattle • Copper • Liver • Paspalum notation • Sulfur

	Introduction

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The importance of S as a plant nutrient has been has been reviewed previously (Coleman, 1966; Martin and Walker, 1966). Concerns over S deficiency in Florida bahiagrass (Paspalum notatum), the predominant forage grass for grazing cattle in Florida, have arisen (Rechcigl et al., 1989). In the past, fertilizer impurities provided forages with S, but with the refinement of modern fertilizer manufacturing processes, S contamination is uncommon. Therefore, the effect of S on bahiagrass quality and the effect of increased forage S on the Cu status of grazing cattle is an important issue.

Rechcigl (1991) reported on a 3-yr study investigating the effect of ammonium sulfate fertilization of bahiagrass at a site in south-central Florida. In their study, the application of S via ammonium sulfate resulted in higher forage S concentrations (0.23 and 0.30% for applications of 86 and 174 kg of S/ha, respectively) compared to bahiagrass fertilized with ammonium nitrate (0.10% S).

Forage Mo is a commonly recognized contributor to Cu deficiencies in cattle, but adequate dietary S is required in this antagonism. Molybdenum combines with S to form a thiomolybdate complex. Thiomolybdates bind with Cu to form an insoluble complex, rendering Cu unavailable for absorption (Mason, 1990; Suttle, 1991).

Impaired immune competence is the likely result of Cu deficiency in cattle (Boyne and Arthur, 1986; Xin et al., 1991). Sulfur-molybdenum-induced Cu deficiency has a direct impact on the ability of cattle to mount a normal response to viral infection (Arthington et al., 1996). This alteration in immune competence may result in failure to respond to vaccination along with increased energy losses during disease exposure.

The objectives of this study were to determine the effect of agronomic levels of ammonium sulfate fertilization on bahiagrass S concentrations and determine whether an increase in forage S affects the Cu status of cows consuming this forage.

	Materials and Methods

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Pastures, Fertilizer Treatments, and Forage Sampling: Exp. 1.
This study was conducted over 2 yr (1999 and 2000). Pasture replicates (16.2 ha; n = 2/treatment) consisted of established bahiagrass grown on a Myakka soil (sandy siliceous, hyperthermic, Aeric Alaquod). Each pasture received the same fertilizer treatment in each growing season. The treatments consisted of, 1) 67 kg N/ha from ammonium sulfate (AS), 2) 67 kg N/ha from ammonium nitrate (AN), and 3) control (no fertilizer; C). Ammonium sulfate contains 24% S; therefore, AS-fertilized pastures received 77 kg of S/ha. Date of fertilizer application varied each year as dictated by spring precipitation (May 7 and March 2 for 1999 and 2000, respectively). Sampling of forage regrowth was conducted at 28-d intervals by the collection of whole plants (four samples/pasture) in randomly distributed 1-m² grazing exclusion cages. Additionally, a 1.08-m² area outside of, but adjacent to, each cage was sampled for an estimate of forage availability. Forage samples were cut using a Sensation mower (Sensation Corp., Omaha, NE) at a stubble height of 7.5 cm, dried in a forced-air oven at 50°C, and ground to pass a 1-mm screen. Forage N and in vitro organic matter digestibility (IVOMD) analysis were conducted at the Forage Evaluation Support Laboratory, University of Florida, Gainesville. Briefly, for N analysis, samples were digested using a modification of the aluminum block digestion procedure of Gallaher et al. (1975). Sample weight was 0.25 g, catalyst used was 1.5 g of 9:1 K₂SO₄:CuSO₄, and digestion was conducted for at least 4 h at 375°C using 6 mL of H₂SO₄ and 2 mL of H₂O₂. Nitrogen in the digestate was determined by semiautomated colorimetry (Hambleton, 1977). For IVOMD analysis, a modification of the two-stage technique (Tilley and Terry, 1963) was used as previously described (Moore and Mott, 1974). Rumen fluid was obtained from donor cows consuming bermudagrass (Cynodon dactylon) hay and provided with 450 g of soybean meal 1 h prior to collection. Forage mineral analysis was performed by A&L Southern Agricultural Laboratories, Pompano Beach, FL, using atomic absorption methods previously described (Wolf, 1982).

Animals: Exp. 1.
In 2000, the effect of fertilizer treatment on cow liver Cu concentrations was evaluated. The animals utilized in these experiments were cared for by acceptable practices as outlined in the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching Consortium,(1988). Liver biopsy collections were performed by a trained technician using techniques previously described (Arthington and Corah, 1995) and approved by the University of Florida, Institutional Animal Care and Use Committee (Project #A603). Random liver tissue samples were collected (n = 12; four/treatment) at the start and end of the study period (117 d) in 2000. Liver tissue samples were collected, handled, and analyzed for mineral concentrations using methods previously described (Arthington et al., 1996). Assay variation was controlled using bovine liver standards (National Institute of Standards and Technology, Gaithersburg, MD).

Differences in available forage due to fertilizer treatment were expected, and therefore stocking rates were applied based on predicted forage availability as shown by a previous study (Rechcigl, 1991) such that available forage would not be limiting in any treatment. Pastures were initially stocked (Period 1) at 2.0, 2.7, and 4.1 ha/cow for AS, AN, and C, respectively, during the first 61 d of grazing. During the final 56 d of grazing (Period 2), stocking rates were increased to reflect greater forage availability (1.8, 2.3, and 3.2 ha/cow for AS, AN, and C, respectively). Group cow body weights were collected for each pasture at the start and end of each grazing period. Each pasture was provided a single mineral box providing free-choice access to a balanced salt-based trace mineral supplement containing 0.25% Cu from Cu sulfate (Table 1). Mineral intake was not monitored. The absence of this information is important when considering the effect of fertilizer treatment on cow mineral status. Therefore, a second controlled-mineral feeding experiment was conducted.

In Exp. 2, Cu treatments were delivered to pens, therefore, average liver Cu concentration for the pen was used as the experimental unit. For multiple measures of liver mineral concentration, over time, a split-plot design was used with pen as the whole-plot treatment and time as the subplot. Treatment means were compared using least significant differences using the error associated with time x pen (treatment) interaction.

	Results

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Exp. 1: Bahiagrass Quality.
Compared to unfertilized pastures, plant tissue N was higher (P < 0.05) in both AS- and AN-fertilized pastures in 2000, but not in 1999 (Table 3). Plant tissue S was greater (P < 0.001) in bahiagrass fertilized with AS in both 1999 and 2000 compared to AN and C (Table 3). Nominal increases in forage IVOMD were realized by fertilization regardless of N source in each year (Table 3). Forage K and Mn were increased (P < 0.05) in AS-fertilized pastures compared to AN and C (0.41, 0.31, and 0.32 % for K and 50.8, 45.5, and 45.5 ppm Mn for AS, AN, and C, respectively). Similarly, forage Zn concentrations were greater (P < 0.05) in AS-fertilized pastures compared to C, but not AN (61.0, 55.3, and 50.4 ppm Zn for AS, AN, and C, respectively). Fertilizer treatment did not affect other forage mineral concentrations analyzed for this study (average macromineral concentrations = 0.62, 0.14, 0.19, and 0.05 % for Ca, P, Mg, and Na and average micromineral concentrations = 73.0, 33.2, and 8.1 ppm for Al, Fe, and Cu, respectively).

Animal Performance and Mineral Status.
Cow ADG was not affected by fertilizer source (0.95, 1.16, and 1.13 and 0.45, 0.32, and 0.61 kg/d for AS, AN, and C during Periods 1 and 2, respectively). Average available forage was higher (P < 0.05) during Period 2 than during Period 1 but was not affected by fertilizer treatment (277, 259, and 277 and 321, 473, and 379 kg/cow for AS, AN, and C in Periods 1 and 2, respectively).

Cows grazing pastures fertilized with AS had lower (P < 0.05) liver Cu concentrations at the end of the grazing season compared to cows grazing AN and C (Table 4), and cows grazing AN-fertilized pastures had lower (P < 0.05) liver Cu concentrations than cows grazing C. Liver Fe, Mn, Mo, and Zn were not affected by fertilizer source. A random collection of 12 liver samples at the start of the study period revealed an initial liver Cu concentration of 68.4 ± 7.9 ppm. These results suggest that the cows had marginal liver Cu stores when they initially entered the study (McDowell, 1992). Cattle grazing AN and C pastures had normal liver Cu concentrations at the end of the study period (McDowell, 1992; Table 4).

View larger version (14K): [in this window] [in a new window]   Figure 1. Liver Cu concentrations in postpartum Brangus heifers following supplementation with 123 mg of Cu/d from inorganic (Cu sulfate, ) and organic (Availa-Cu, •) sources. Treatment x day interaction was nonsignificant (P = 0.44). Main effect of treatment tended (P = 0.09) to differ (mean liver Cu concentrations pooled over all times = 156 ± 5.7 and 119 ± 5.7 ppm for Availa-Cu and Cu sulfate, respectively).

	Discussion

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Forage N concentration was greater in fertilized than in unfertilized pastures in 2000, but not in 1999 (Table 3). The growing season in 1999 was late due to spring drought, which may explain the lack of N uptake in the plant. However, the drought conditions also extended into 2000, whereas bahiagrass N concentration did respond to fertilization. On-site measures of rainfall were not collected; however, rainfall at the Range Cattle Research and Education Center (approximately 80 km) was 23.5 and 35.2 cm below a 58- and 59-yr average for the grazing months in 1999 and 2000, respectively.

Nominal increases in forage IVOMD were realized by fertilization, regardless of N source in each year (Table 3). Slight improvements in the digestibility of AS-fertilized bermudagrass (Cynodon dactylon; Mathews et al., 1994) and small grains (Hardt et al., 1991) have been reported previously. This improvement in digestibility may be related to increased forage S, which may have a complementary impact on the ruminal microbial environment. Increased digestibility of pangola grass (Digitaria eriantha) has been reported with S supplementation of sheep (Rees et al., 1974).

The increases in mineral concentration of AS-fertilized forages may be a result of improved mineral solubility as a result of lower soil pH. Ammonium sulfate application decreases soil pH, which has been associated with an increase in Mn uptake in corn (Zea mays;Miner et al., 1986). In this study, soil pH was 5.7, compared to 6.2 in AS- and AN-fertilized fields, respectively. In the current study, soil pH was only measured in 2000, whereas the soil pH of AS-treated pastures was similar to C (pH = 4.7 and 4.9 for AS and C, respectively), suggesting that other factors may also contribute to the observed increase in mineral concentration in AS-fertilized bahiagrass.

Animal Mineral Status.
Decreases in circulating plasma Cu are associated with liver Cu concentrations of approximately 40 ppm and lower (Claypool et al., 1975). Once these concentrations are achieved, animals are considered severely deficient because availability of Cu to peripheral tissue sites is compromised. In general, dry liver Cu concentrations below 25 to 75 ppm are considered deficient for cattle (McDowell, 1992). Thus, the cows in the present study may have been Cu-deficient when they initially entered the study: their initial liver Cu concentrations averaged 68.4 ppm. Liver Cu concentrations are the most reliable indicator of Cu status in cattle. Normal liver Cu concentrations in Florida cattle range between 100 and 300 ppm on a DM basis (Ammerman, 1969). At the end of the study in 2000, cows grazing AS pastures were still considered marginally Cu-deficient. In contrast, cows grazing AN and C pastures had liver Cu stores into the adequate range (McDowell, 1992, Table 4). The most likely explanation for the low liver Cu concentrations in cows grazing AS-fertilized pastures is high forage S concentrations. The 2-yr average S concentration for forage samples collected on AS-treated pastures was 0.50%. The antagonistic effect of S on Cu metabolism is well recognized (Mason, 1990). Suttle (1974) reported a 56% reduction in the increase in plasma Cu following Cu sulfate supplementation of Cu-deficient sheep fed a diet containing 0.40 vs 0.10% S. A review of the literature (NRC, 1996) suggests that the maximum limit for potential S toxicity in cattle is 0.40%, and S toxicity in ruminants has been reviewed previously (Kandylis, 1984). Even though this threshold was exceeded in cattle grazing AS pastures, no signs of S toxicity were noted. Excessive dietary S is often associated with a neurological disease in feedlot cattle called polioencephalomalacia (Jeffrey et al., 1994; McAllister et al., 1997). Even though cattle grazing AS pastures consumed large amounts of S, the only indicator of S excess was their failure to respond to Cu supplementation.

The absence of mineral intake information in Exp. 1 is a shortcoming of the present study when relating cow Cu status to fertilizer treatment. All cows were offered an equal opportunity to consume free-choice mineral. We are not aware of any previous data suggesting that high-S forages may limit free-choice mineral intake. However, we cannot preclude the potential influence of variable free-choice mineral intake on subsequent liver Cu concentrations reported in this study. To provide further insight, a group of heifers grazing AS-fertilized pastures from the same ranch were assessed. Despite the consumption of 142 mg of Cu/d, these heifers were found to have low liver Cu concentrations (52.7 ppm) prior to the start of Exp. 2. Once removed from the pastures containing high concentrations of S, Cu-deficient heifers were able to rapidly respond to Cu supplementation from both inorganic (Cu sulfate) and organic (Availa-Cu) sources. Heifers receiving an organic Cu source tended (P = 0.09) to have higher mean liver Cu concentrations than heifers supplemented with Cu sulfate (156 ± 5.7 and 119 ± 5.7, respectively).

	Implications

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Application of agronomic rates of ammonium sulfate (67 kg N/ha) to bahiagrass pasture results in significant increases in forage sulfur concentrations. Increased forage sulfur can affect copper metabolism in grazing ruminants. Cattle grazing bahiagrass containing 0.50% sulfur had lower liver copper concentrations than cows grazing bahiagrass containing 0.22 and 0.25% sulfur. Upon removal from high-sulfur forages, copper-deficient cattle are able to respond to copper supplementation from both organic and inorganic sources. These data suggest that the application of sulfur-containing fertilizer may affect the copper status of grazing cows. In regions where grazing cattle may be prone to copper deficiency, specific attention to fertilizer source is warranted.

	Footnotes

 
¹ This research is supported by the Florida Agric. Exp. Stn. and is approved for publication as R-08397.

³ Appreciation is expressed to Zinpro Corp., Eden Prairie, MN and Honeywell, Hanover, PA for partial funding support of this study. The use of trade names and(or) products in this publication does not imply endorsement or criticism of those products.

⁴ Present address: 5007 60th St. E., Bradenton, FL 34203-9511.

⁵ Present address: AgriLogic, Inc., P.O. Box 9990, College Station, TX 77842-7990.

Received for publication September 28, 2001. Accepted for publication March 22, 2002.

	Literature Cited

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Ammerman, C. B. 1969. Recent developments in cobalt and copper in ruminant nutrition: A review. J. Dairy Sci. 53:1097–1107.

Arthington, J. D., and L. R. Corah. 1995. Liver biopsy procedures for determining the trace mineral status in beef cows; Part II (Video, AI 8134). Extension TV, Dept. of Communications, Cooperative Extension Service, Kansas State Univ., Manhattan.

Arthington, J. D., L. R. Corah, and F. Blecha. 1996. The effect of molybdenum-induced copper deficiency on acute-phase protein concentrations, superoxide dismutase activity, leukocyte numbers, and lymphocyte proliferation in beef heifers inoculated with bovine herpesvirus-1. J. Anim. Sci. 74:211–217.[Abstract]

Boyne, R., and J. R. Arthur. 1986. Effects of Mo or iron induced copper deficiency on the viability and function of neutrophils from cattle. Res. Vet. Sci. 41:417–419.[Medline]

Claypool, D. W., F. W. Adams, H. W. Pendell, N. A. Hartmann, Jr., and J. F. Bone. 1975. Relationship between the level of copper in the blood plasma and liver of cattle. J. Anim. Sci. 41:911–914.[Abstract/Free Full Text]

Coleman, R. 1966. The importance of sulfur as a plant nutrient in world crop production. Soil Sci. 101:230–239.

Consortium. 1988. Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching. Consortium for Developing a Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching, Champaign, IL.

Demetriou, J. A., P. A. Drews, and J. B. Gin. 1974. Enzymes. In: R. J. Henry, D. C. Cannon, and J. W. Winkelman (ed.) Clinical Chemistry. 2nd ed. pp 857–864. Harper and Row, Hagerstown, MD.

Gallaher, R. N., C. O. Weldon and J. G. Futral. 1975. An aluminum block digester for plant and soil analysis. Soil Sci. Soc. Am. Proc. 39:803–806.

Hambleton, L. G. 1977. Semiautomated method for simultaneous determination of phosphorus, calcium and crude protein in animal feeds. JAOAC 60:845–852.

Hardt, P. F., W. R. Ocumpaugh, and L. W. Greene. 1991. Forage mineral concentration, animal performance, and mineral status of heifers grazing cereal pastures fertilized with sulfur. J. Anim. Sci. 69:2310–2320.[Abstract]

Jeffrey, M., J. P. Duff, R. J. Higgins, V. R. Simpson, R. Jackman, T. O. Jones, S. C. Mechie, and C. T. Livesey. 1994. Polioencephalomalacia associated with ingestion of ammonium sulphate by sheep and cattle. Vet. Rec. 134:343–348.[Abstract]

Kandylis, K. 1984. Toxicology of sulfur in ruminants: A review. J. Dairy Sci. 67:2179–2187.

Martin, W. E., and T. W. Walker. 1966. Sulfur requirement and fertilization of pasture and forage crops. Soil Sci. 101:248–257.

Mason, J. 1990. The biochemical pathogenesis of Mo-induced copper deficiency syndromes in ruminants: Toward the final chapter. Ir. Vet. J. 43:18–22.

Mathews, B. W., L. E. Sollenberger, and C. R. Staples. 1994. Sulfur fertilization of bermudagrass and effect on digestion of nitrogen, sulfur, and fiber by nonlactating cows. J. Haw. Pac. Agric. 5:21–29.

McAllister, M. M., D. H. Gould, M. F. Raisbeck, B. A. Cummings. 1997. Evaluation of ruminal sulfide concentrations and seasonal outbreaks of polioencephalomalacia in beef cattle in a feedlot. J. Am. Vet. Med. Assoc. 211:1275–1279.[Medline]

McDowell, L. R. 1992. Copper and molybdenum. In: T. J. Cunha (ed.) Minerals in Animal and Human Nutrition. pp 176–204. Academic Press, San Diego, CA.

Miner, G. S., S. Traore, and M. R. Tucker. 1986. Corn response to starter fertilizer acidity and manganese materials varying in water solubility. Agron. J. 78:291–295.[Abstract/Free Full Text]

Moore, J. E., and G. O. Mott. 1974. Recovery of residual organic matter from in vitro digestion of forages. J. Dairy Sci. 57:1258–1259.[Abstract/Free Full Text]

NRC. 1984. Nutrient Requirements of Beef Cattle. 6th ed. National Academy Press, Washington, DC.

NRC. 1996. Nutrient Requirements of Beef Cattle. 7th ed. National Academy Press, Washington, DC.

Rechcigl, J. E. 1991. Sulphur fertilization improves bahiagrass pastures. Better Crops Plant Food 75:22–24.

Rechcigl, J. E., G. G. Payne, and R. J. Stephenson. 1989. Influence of sulfur and nitrogen on bahiagrass. In: Proc. 16th Int. Grassland Congr., Nice, France. pp 27–28.

Rees, M. C., D. J. Minson, and F. W. Smith. 1974. The effect of supplementary and fertilized sulphur on voluntary intake, digestibility, retention time in the rumen, and site of digestion of pangola grass in sheep. J. Agric. Sci. 82:419–422.

Suttle, N. F. 1974. Effects of organic and inorganic sulphur on the availability of dietary copper to sheep. Br. J. Nutr. 32:559–568.[Medline]

Suttle, N. F. 1991. The interactions between copper, Mo, and sulphur in ruminant nutrition. Annu. Rev. Nutr. 11:121–140.[Medline]

Tilley, J. A., and R. A. Terry. 1963. A two-stage technique for the in vitro digestion of forage crops. J. Grassl. Soc. 18:104–111.

Wolf, B. 1982. A comprehensive system of leaf analysis and its use for diagnosing crop nutrient status. Comm. Soil Sci. Plant Anal. 13:1035–1059.

Xin, Z., D. F. Waterman, R. W. Hemken, and R. J. Harmon. 1991. Effects of copper status on neutrophil function, superoxide dismutase, and copper distribution in steers. J. Dairy Sci. 74:3078–3085.[Abstract]

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