PHOSPHORUS INFLUENCE ON GROWTH AND REPRODUCTION OF BEEF CATTLE

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1 PHOSPHORUS INFLUENCE ON GROWTH AND REPRODUCTION OF BEEF CATTLE SUARY Ninety-six 7-mnth-ld Herefrd heifers (tw replicates f 48, ne year apart) were individually fed fr 2 years a basal ratin cntaining.14% phsphrus n an "as fed" basis, which apprxiamted 66% NRC recmmendatins. Frty-eight f the animals were limited t this lw phsphrus (P-) diet. The ther 48 (P+) received sufficient mnsdium phsphate, tp dressed n the basal ratin, t elevate phsphrus intake t.36% n an "as fed" basis (174% NRC recmmendatins). The average daily weight gain fr all grups was.45 kg. Feed efficiency was similar fr the tw grups. There was n evidence f lack f appetite r depraved appetite in either grup; nr was there a difference in age f puberty. The P- cattle had a 6% pregnancy rate with 1% live calves cmpared t 1% and 3%, respectively, fr the P+ cattle. These differences were nt significant. After mnths n trial (apprximately 16 mnths f age) n difference in rib bne mrphlgy was discernable frm micrradigraphs. Bld and serum levels f phsphrus temprarily increased in the P+ cattle, but at 16 mnths f age were cmparable t the less fluctuating values in the P- cattle. The phsphrus levels fr bne and muscle were similar each year and fr each treatment. Urine and fecal phsphrus excretin was significantly higher in the P+ than in the P- cattle. (Key Wrds: Phsphrus, Nutritin, Reprductin, Grwth, Bne rphlgy, Beef Cattle.) JAnimal, Dairy and Veterinary Sciences Department, Cllege f Agriculture, Utah State Agricultural Experiment Statin, Utah State University, Lgan, Jurnal Paper N Additinal supprt funds frm USDA, ARS and Fur Crners Reginal Cmmissin; materials grants frm Leslie Fds Inc., Internatinal inerals and Chemicals Crp., and Diamnd-shamrck Chemical C.; analytical mnitring by Ralstn Purina C. and Intermuntain Labratry Inc.; cntributins frm Western Reginal Research 112. J. W. Call, J. E. Butcher, J. T. Blake, R. A. Smart and J. L. Shupe ~ Utah State University Lgan, INTRODUCTION Phsphrus in the ruminant diet was researched by Theiler et ak (128) and by several ther scientists during the early thirties (Eckles et al., 132, 135; Hendersn and Weakly, 13; Kleiber et al., 136; Theiler and Green, 132). Aphsphrsis in catle is reprted t he widespread and phsphrus supplementatin is a cmmn practice. any scientists have assciated reduced reprductive perfrmance with a phsphrusdeficient diet. Ovarian dysfunctin and reduced fertility in cattle were reprted by Hignett and Hignett, 151; Shrt and Bellws, 171; Theiler et al., 128. Fertility and calving rates are quite sensitive t phsphrus intake accrding t a phsphrus review by Prestn, 176. Reduced weight gains were reprted by Hlchuh 171; rrisn, 156; Winks and Laing, 168. Inappetance was reprted by rrisn, 156. Cnversely, ther scientists reprted that phsphrus supplementatin had little influence n reprductive efficiency (Eckles et al, 135; Palmer et al., 141). The cntradictry reprts are due, at least in part, t difficulty in maintaining individual phsphrus intake and the arduus prblem f develping an uncmplicated phsphrus deficiency and defining the resulting physipathlgy. There is evidence (Ck, 171) that lw phsphrus cntent is crrelated with lw crude prtein in plants. In many f the literature reprts f phsphrus deficiency it is nt clear whether there were adequate levels f all nutrients ther than phsphrus. This research was initiated t cmpare the influence f tw dietary levels (lw and high) f phsphrus n feed cnsumed, bdy-weight gain, puberty and reprductive efficiency f beef cattle. ATERIALS AND ETHODS Ninety-six Herefrd heifers, apprximately 7 mnths ld, averaging 165 kg, were used t study the influence f phsphrus n reprductive prcesses. The first 48 animals (1 cattle) were 216 JOURNAL OF ANIAL SCIENCE, Vl. 47, N. 1, 178

2 PHOSPHORUS INFLUENCE-BEEF CATTLE 217 purchased in the fall, 172, at weaning time frm ne wner. The secnd grup f 48 animals (2 cattle) was purchased a year later frm a different wner. The heifers were hused in grups but were individually fed with ttal daily feed cnsumptin measured and recrded. Animals had free access t water. Bedding cnsisted f wd shavings, straw r bth. The animals were hused in pen sheds with access t crrals and prvided with individual tie stalls. The basal diet cnsisted f varius cmbinatins f pelleted r chpped alfalfa, chpped wheat straw and chpped grass hay, with beet mlasses as a tp dressing. The diet was fmulated t be phsphrus-deficient (averaging. 14% "as-fed" basis) yet prvide adequate energy, prtein, minerals and vitamins. Prprtins f the ratin were adjusted peridically t maintain, as nearly as pssible, a.5 kg daily gain during the grwing perid and t prvide adequate nutrients fr pregnancy and lactatin, except the lw-phsphrus cntent was maintained. A phsphrus-free mineralvitamin mixture was fed free-chice, cntaining salt, manganese, inc, idine, cpper, cbalt, mlybdenum and vitamins A and D. It was prprtined s that when cnsumed at the rate f.22 g/kg bdy weight per day these nutrients were prvided in quantities equal t r exceeding recmmended levels (NRC). The rughage prtin f the diet averaged apprximately 15% prtein. lasses was added as needed fr an energy surce. Frty-eight animals received nly the basal diet and cmprised the lw-phsphrus (P-) grup. The ther 48 animals received the basal diet, but tp-dressed with mnsdium phsphate at the rate f.34 g/kg bdy weight per day (.88 g f elemental phsphrus/kg bdy weight per day) and cmprised the high phsphrus (P+) grup. At 2 mnths f age the P+ heifers in the secnd replicate (2) were reduced in the mnsdium phsphate t.25 g/kg bdy weight and t.21 kg at 24 mnths f age. This was nt a prblem with the 1 replicate because they were placed n pasture, as explained belw. Feed prir t purchase and peridic representative samples f the basal diet fed thrughut the experiment were analyed fr 2Blake, J.T. 16. Unpublished analytic prcedure. ~A highly specific anti-prgesterne was supplied curtesy f Dr. G.D. Niswender, Department f Physilgy, Clrad State University, Frt Cllins. phsphrus and calcium cntent. Samples f fed as described until apprximately 18 mnths f age. They were then placed in lw-phsphrus, irrigated pastures. The P- grup received a phsphrus-free mineral-vitamin supplement ad libitum. The P+ grup received ad libitum the same mineral-vitamin mixture but frtified with mnsdium phphate. In the fall, (apprximately 21 mnths f age) bth grups f the 1 cattle were again returned t dry lt, but were grupfed n lw phsphrus grass hay. The P+ grup received free chice the phsphrus frtified pasture eaten by the first replicate (1) animals were als analyed peridically fr phsphrus cntent (air dry basis). Analysis f feed was dne clrimetrically, by a mlybate-reductin methd. The (1) animals were randmly divided int P- and P+ grups. All were hused and individually mineral-vitamin mixture, while the P- grup received the phsphrus-free mineral-vitamin mixture, ad libitum. The animals calved in drylt and after calving were returned t irrigated pastures, this time withut a phsphrus r mineral-vitamin supplementatin. Feed cnsumptin in the pastures was estimated by bdy weight gains and by nutrient analysis f the native grasses. The secnd replicate (2) animals remained cnfined and individually fed fr a cmplete 2-year perid. This grup f cws was bred and calved in dry lt. All animals in bth replicates were bred naturally via 3-mnth expsrue t bulls. The cws were checked mnthly fr pregnancy status after expsure t the bulls. In additin, they were weighed and bled bi-mnthly r mnthly. The bld (and serum) frm each perid were analyed fr phsphrus cntent. At the beginning f the trial, part f the 13th rib and a piece f intercstal muscle were remved frm the right side f each heifer. A secnd rib and muscle samples were remved frm the left side when the heifers were! 6 mnths ld. Bne and muscle were analyed fr phsphrus, and the bne used fr micrradigrpahic studies. The whle bld and serum, including bld prteins, were digested and analyed. Similarly, the bne and defatted muscle were digested. Tissues were digested with 6/4 v/v f nitric and perchlric acid by an unpublished technique 2. The tissues were analyed clrimetrically fr phsphrus (Hycel reagent). Analyses fr prgesterne were als perfrmed using a radiimmunassay 3 methd mdified frm that described by Smith and Hafs (173).

3 218 CALL ET AL. Phsphrus balance studies, using ttal urine and feces cllectin, were cnducted at selected intervals fr a 5-day perid frm randmly selected cws (fur at a time). Rectal examinatins were perfrmed at 2-week intervals t determine nset f puberty, beginning with the first week f April (apprximately 1 year f age) and cntinuing fr 1 weeks. The varies were palpated fr fllieles r crpus luteum frmatin, r bth. RESULTS The ttal feed intake ("as-fed" basis) ver a 2-year perid fr all the animals averaged 7.2 kg/day fr the P- grup and 7.26 kg/day fr the P+ grup. The feed cnsumptin by 3-mnth perids, fr each grup, is given in table I and reflects the appetite f each grup with limitatins placed n the animals that wuld eat the mst feed. The number f animals that were restricted in feed cnsumptin were the same in bth grups. The daily phsphrus cnsumptin, by 3-mnth perid, is given in table 2. These data shw phsphrus intake in relatin t NRC recmmendatins (176), fr grwth, breeding, pregnancy and lactatin. The average phsphrus cncentratin in the basal (P-) grup was.14% and fr the P+ grup was the. 14% plus.22% frm supplementatin, ttal.36%. Phsphrus intake was peridically altered with changes in the ratin, with time, and with bilgical status changes. In relatin t NRC recmmendatins, the phsphrus intake varied as the animals, ratin and bilgical status changed. The percent f the NRC recmmendatins fr the P- cattle gt as lw as 52% and as high as 88% with an average f 66% f daily phsphrus intake, and a lw f 64% and a high f 272% with an average f 174% fr the P+ cattle. These Variatins were nt as wide in the P+ cattle. Variatins were nt as wide in the individual feeding. Average calcium cntent was high (1.1%) and average phsphrus cntent lw (.14%) in the basal ratin. Cnsequently, the Ca/P rati was wide (7.14:1) fr the lw phsphrus cattle. The rati was less (3.5:1) fr the phsphrus supplemented cattle. There were cmpsitinal variatins in bth Ca and P f the basal ratin and in the phsphrus supplementatin rate, as described previusly. Therefre, the Ca/P rati became as extreme as 8.6:! in the P- grup and 1.31:1 in the P+ grup. There were n significant differences in bdy grwth and weight (table 3) between the P- and P+ cattle. The grwing heifers gained an average f.44 kg/day in the P- grup and.45 kg/day in the P+ grup, during the first 15 mnths n the trial, r thrugh the secnd trimester f pregnancy. TABLE 1. Perid FEED INTAKE OF CATTLE RECEIVING TWO LEVELS OF PHOSPHORUS OVER A 2-YEAR PERIOD Feed Cnsumed a kg/day ("as-fed" basis) P- grup (66% NRC) P+ grup (172% NRC) 1 b 2 c 1 b 2 c Dec-Feb arch-ay 5. +.t June-Aug t2 6.I (breeding perid) Sept-Nv 7.7 d d Dec-Feb 7. d d arch-ay 8.5 d d (calving perid) June-Aug.5 d d (breeding perid) Sept-Nv 8.7 d d afeed cnsisted f alfalfa, grass, straw, beet mlasses. b24 Herefrd heifers purchased in 172 (a ttal f 48), apprximately 7 mnths f age. c24 Herefrd heifers purchased in 173 (a ttal f 48), apprximately 7 mnths f age. destimated feed cnsumed; animals placed n pasture then grup-fed with grass hay, weight as fed.

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5 22 CALL ET AL. There was n apparent difference in feed utiliatin. The P- grup required kg f feed fr each kilgram f grwth cmpared t kg f feed fr each kilgram f grwth in the P+ grup. After l days n trial, the phsphrus cncentratins (replicatin average, table 4) in bth whle bld (16. mg%) and bld serum (8.! mg%) in the P- cattle were cnsiderably lwer than the repsective cncentratins (1. l mg%, 11.7 mg%) in the P+ cattle. Apprximately mnths later (16 mnths f age) these differences had nearly disappeared; the whle bld and serum cncentratin replicatin averages were 16.3 mg% and 7.1 mg% frvthe P- cattle and 17.6 rag% and 8.7 rag% fr the P+ cattle (table 4). Rib-bne levels f phsphrus (replicatin averages n "as-is" basis) fr bth years ranged frm.6% at the beginning f the trial t 8.4% at 16 mnths f age in the P- grup. In the P+ grup the range was.4% at the beginning f the trial and 8.7% at 16 mnths f age. uscle phsphrus cntent ("as-is" basis) was.21% at 7 mnths (beginning f the trial) and.24% at 16 mnths fr the P- grup, cmpared t.24% (beginning f the trial) and.24% at 16 mnths fr the P+ grup. The rib-bne sectins, n grss examinatin, appeared the same frm bth grups. Radigraphs f rib crss sectins were similar between grups. Histlgical sectins f the ribs did nt shw any changes that culd be related t treatment. icrradigraphs evidenced n difference in degrees f hypcalcificatin and hypercalcificatin, nr did they demnstrate excessive demineraliatin. Frm phsphrus balance trials cnducted when the animals were pregnant, it was fund that the P- animals were excreting apprximately.14 g/day f phsphrus (l.8%/day ttal phsphrus intake) in the urine cmpared with 5.5 g/day (16.7%/day f ttal phsphrus intake) in the P+ grup. The level f phsphrus in the feces was 4.58 g/day (57% f ttal phsphrus intake) in the P- grup, cmpared t g/day (43% f the ttal phsphrus intake). Puberty studies shwed prgesterne was at a lw level in the heifers until the first f April (12 mnths f age), at which time the level started increasing. There was n apparent difference in prgesterne levels assciated with the level f dietary phsphrus, hwever, the P- heifers tended t initiate varian activity slightly earlier than did the P+, but a greater percentage f P+ were cycling later in the seasn (table 5). Cnceptin rates, calving rates and calves brn alive were similar in bth grups (table 6). An accunting f the animals excluded frm the experiment is als given in table 6. The lss f the animals was nt assciated with the phsphrus treatments. There were tw sets f twins brn in the P+ (1) grup during the first calving. The calving interval is given in table 7. The calving interval cmmenced with the day the first calf was brn f each year. There were three cws that calved beynd the 6th day within the P- grup, whereas nne calved in the P+ grup beynd the 6th day. Hwever, the mean calving day was 1 days fr the P- grup and 2 days fr the P+ grup. Discussin The individual differences in feed intake were assciated with differences in appetite. Certain animals cnsistently wanted mre feed and thers wuld have difficulty in eating the amunt they received. Sme animals were incnsistent in the amunt f feed they cnsumed. It was necessary t limit sme f the hungry animals t standardie the gain f the heifers; this limited ur ability t determine if appetite differed between the P- and P+ grup. Therefre, a cntrlled study was initiated with six cws in the P+ grup and six cws in the P- grup, selected at randm. This study failed t shw any signficant appetite difference when all cntrlled cattle were fed the regular ratin plus straw t maximum intake. Hwever, there was a slight trend f reduced feed intake f the lw-level phsphrus grup (table 1). These results are in agreement with Lng et al. (175), wh reprted the necessity f ging t.7 t. % phsphrus t btain depressed appetite in steers. Hwever, Tillman et al. (15), in a steer feeding experiment, fund a benefit in feed cnsumptin and daily gain by increasing phsphrus frm the basal diet f. 14 t. 17 and.2% in the diet. There was little difference between the first and secnd year animals in feed efficiency. The secnd-year animals had a trend fr higher efficiency than the first. The difference culd be assciated with the different breeding and, f curse, a difference in feed quality and the envirnment variatins frm year t year. There was n apparent difference in feed efficiency between the P- grup and the P+ grup with each replicatin. Cattle under certain range cnditins are subjected t feeds as lw r lwer in phsphrus as the basal diet (.14%) in the present experiment. Hwever, seldm are range cattle subjected t such marginal phsphrus intake fr an extended time

6 PHOSPHORUS INFLUENCE-BEEF CATTLE 221 TABLE 3. BODY WEIGHTS OF CATTLE RECEIVING TWO LEVELS OF PHOSPHORUS FOR A 2-YEAR PERIOD P- (66% NRC) P+ (172% NRC) Gain/ Ending date 1a 2 b Gain/day 1a 2 b day... (kg)... Nvember February ay August Nvember February Grwth rate -- mean.44 Grwth rate -- mean.45 August d Nvember afirst grup f heifer calves purchased Nvember, 172. bsecnd grup f heifer calves purchased Nvember, 173. Cean grwth rate first 15 mnths. dthe ay weights were mitted because f calving variability. TABLE 4. TISSUE PHOSPHORUS OF CATTLE RECEIVING TWO LEVELS OF PHOSPHORUS P- grup a P+ grup a Tissue and time Bne (%)b Initial Pst uscle (%)b Initial Pst Whle bld (mgm %) Tenth day c Pst Bld serum (mgm %) Tenthday c Pst alw P-(.14%) and high P+ (.36%) phsphrus treatment grups. brib bne and intercstal muscle; values are n fresh "as is" basis. Initial bipsies were taken at 7 mnths f age and pst samples at 16 mnths f age. CBipsies taken prir t assigning calves t treatment grup; were 7 mnths ld.

7 222 CALL ET AL. TABLE 5. FIRST OVULATION (C.L. FORATION), ESTIATED BY RECTAL PALPATION EXPRESSED BY RATIO OF ANIALS WITH C.L. AND NUBER OF ANIALS IN EACH GROUP OF CATTLE RECEIVING TWO LEVELS OF PHOSPHORUS Examina- P- (66 NRC) P+ (172% NRC) tin 1 a 2 b Sum % la 2 b Sum % Day 1 c [24 1/24 1/48 2 2[24 1/23 d 3/47 6 Day l5 2/24 5/24 7/ /24 1/23 3/47 6 Day2 6/24 1/ /24 3/23 7/47 15 Day 43 1/24 15/24 25/ [24 15/23 22/47 47 Day 57 13/24 18/24 31/ /24 21/23 32/47 68 Day 71 15/24 2/24 35/ /24 22/23 38/47 81 afirst grup f heifers purchased Nvember, 172. bsecnd grup f heifers purchased Nvember, 173. CFirst week f April fr the first exam (apprximately 1 year f age). dne animal in the grup died frm entertxemia. as they have been in this research prject. By the ARC (165) recmmendatins, the experimental cattle were mre nearly adequate in phsphrus intake, fr the lighter weights, but mre deficient as bdy weights were increased. One imprtant cntributin f the present research is that it has been demnstrated that beef cattle may perfrm adequately fr 2 years (including grwth, puberty, cnceptin, gestatin and lactatin) n a dietary phsphrus level that is 66% f NRC recmmendatins. Cnversely, ur research has demnstrated that phsphrus supplementatin (172% f NRC recmmendatin) des nt ptimie grwth respnse r reprductive perfrmance. Puberty has been assciated in heifers with sie and age, and because there was n apparent difference in these tw cnditins frm the P+ grup t the P- grup, as expected, n differences existed at puberty. There were mre unbred cws in the P- grup, but their perfrmance was superir t that fund in field cnditins (7% pregnancy rate). Tw sets f twins were brn in the P+ grup during the first calving. The cws that calved late during the first calving were at a disadvantage t cnceive the secnd time. These cws were allwed nly ne expsure t the bull and in ne case the animal came in heat the first time after the bulls were remved. The heric phsphrus levels in this research are higher than levels reprted by ther investigatrs (Hlchuh et al. 171; rrw, 16). The methd used in this study was t digest samples f whle bld and the entire serum aliqut, including the prteins. Traditinally, serum phsphrus levels are reprted fr inrganic phsphrus since the prteins are precipitated prir t analysis. The whle bld values and serum values reprted in this paper permit a mre cmprehensive value fr circulating levels f phsphrus n a high r lw phsphrus ratin. Obstensively, cntinuus verlading f the animal's bdy with phsphrus 72% NRC recmmendatin) fr ur extended perid (2 years) des nt prduce phsphrus txicity, nr des a Ca/P rati as extreme as 8.6:1 cause prblems. Frm a practical standpint, the majr cncern f high level phsphrus supplementatin, then, is the unnecessary cst, since ur research has shwn that large quantities f phsphrus have n beneficial effect in beef cattle. Hw much lwer the phsphrus intake wuld need t be ver an extended time perid in rder t prduce clinical manifestatins is cnjecture. The lw-phsphrus level in these trials was apparently adequate t maintain nrmal pregnancy and grwth.

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10 PHOSPHORUS INFLUENCE-BEEF CATTLE 225 LITERATURE CITED ARC (Agricultural Research Cuncil) the nutrient requirements f farm livestck. N. 2. Ruminants. Ck, C.W In C.. ckell, J.P. Blaisdell, J.R. Gdin (Ed.) Wildland shrubs-their bilgy and utiliatin. USDA Pub. Washingtn, DC. Eckles, C.H., L.S. Palmer, T.W. Gullicksn, C.P. Fitch, W.L. Byd, L. Bishp and J.W. Nelsn Effects f uncmplicated phsphrus deficiency n estrus cycle, reprductin and cmpsitin f tissues f mature dairy cws. Crnell Vet. 25: Eckles, C.H., T.W. Gullicksn and L.S. Palmer Phsphrus deficiency in the ratins f cattle. innesta Agr. Exp. Sta. Tech. Bull. 1. Hendersn, H.O. and C.E. Weakly, Jr. 13. The effect f feeding differnt amunts f calcium and phsphrus upn the grwth and develpment f dairy animals. West Virginia Agr. Exp. Sta. Bull Hignett, S.L. and P.G. Hignett The influence f nutritin n reprductive efficiency in cattle. (The effect f calcium and phsphrus intake n the fertility f cws and heifers.) Vet. Res. 63:62-6. Hlchuh, W., A. Dittrich and S. Legal Effect f different amunts f phsphrus fr pregnant heifers n physilgical values in their prgeny. Nutr. Abstr. and Rev. 41:752. Klieber,.H., H. Gss and H.R. Guilbert Phsphrus deficiency and fd utiliatin. J. Nutr. 12:13 I. Lng, T.A., A.D. Tillman, A.B. Nelsn, W.D. Gallup and B. Davis Availability f phsphrus in mineral supplements fr beef cattle. J. Anim. Sci. 16: rrisn, F.B Feeds and feeding. 6 p. rrisn Publishing C., Ithaca, NY. rrw, D.A. 16. Phsphrus deficiency and infertility in dairy heifers. J. Amer. Vet. ed. Assc. 154:762. N.R.C. 176 Nutrient requirements f dmestic animals, N. 4. Nutrient requirements f beef cattle. Natinal Academy f Sciences. 5th Ed. Palmer, L.S., T.W. Gullicksn, W.L. Byd, C.P. Fitch and J.W. Nelsn The effect f ratins deficient in phsphrus and prtein n vulatin, estrus and reprductin f dairy heifers. J. Dairy Sci. 24:1-21. Prestn, R.L Phsphrus in beef cattle and sheep nutritin. Nat. Feed Ingred. Ass., W. Des ines, IA. Shrt, R.E. and R.A. Bellws Relatinship amng weight gains, age at puberty and reprductive perfrmance in heifers. J. Anim. Sci. 32: Smith, O.W. and H.D. Hafs Cmpetitive prtein binding and radiimmun assay fr teststerne in bulls and rabbits; bld serum teststerne after injectins f L.H. r prlactin in rabbits. Prc. Sc. Exp. Bil. ed. 142:84. Theiler, A., H.H. Green and P.J. Dutit Studies in mineral metablism (III). Building f cattle n phsphrus deficient pasture. J. Agr. Sci. 18: Theiler, A. and H.H. Green Aphsphrsis in ruminants Nutr. Abstr. and Rev. 1:35. Tillman, A.D., J.R. Brethur and S.L. Hansard. 15. Cmparative prcedure fr measuring the phsphrus requirement f cattle. J. Anim. Sci. 18: Winks, L. and A.R. Laing Urea, phsphrus and mlasses supplements fr graing beef weiners. Nutr. Abstr. and Rev. 38:753.