Biological characteristics for assessing low phosphorus intake in finishing swine

Three replicates of a randomized complete-block design in a 3 x 3 factorial arrangement of treatments involving 141 pigs were conducted to evaluate the effect of low P intake on various response criteria in swine from 65 to 95 kg body weight. Total dietary P levels of .09, .21 and .31% were each fed in a Ca:P ratio of 1.1, 1.5:1 or 2:1 for a 35-d experimental period. The basal diet was formulated using corn starch, dextrin and a soy protein concentrate with monosodium phosphate and limestone supplying desired treatment levels of Ca and P. Blood and bones were collected for mineral analysis. Gain and feed performance responses were not affected by Ca:P ration or dietary P level for the 35-d period. Serum inorganic P concentrations declined as Ca:P ratio increased, but increased as dietary P increased. Serum alkaline phosphatase activity increased with higher Ca:P ratios, and decreased as dietary P level increased. Percent bone ash was not influenced by Ca:P ratio, but increased as dietary P level increased. Bone-bending moment was influenced by Ca:P ratio, and increased linearly as dietary P increased. Dietary P level resulted in a linear increase in total bone and its ash component weight, and in the accretion of the ash and organic matrix component. These data suggest that between 65 to 95 kg body weight, percent bone ash was affected by dietary P level, while bone-bending moment, bone component weights, their accretion, both dietary p level and Ca:P ratio.     

Dietary calcium and phosphorus levels for growing swine from 18 to 57 kilograms body weight

A randomized complete block design experiment was conducted using 408 crossbred pigs to evaluate the effects of six dietary Ca/P levels for growing swine (18 to 57 kg). Total dietary P levels ranged from .40 to .90% in .1% intervals with Ca concurrently increased at a 1.3:1 ratio in a 16% protein corn-soybean meal diet. Dicalcium phosphate and limestone were the source of inorganic Ca and P. For the overall trial, daily gain and feed intake improved as dietary Ca/P increased to an approximate level of .65/.50%. An inverse relationship occurred between serum Ca and P, with serum Ca declining and P increasing at the lower mineral levels. Femur, humerus, rib, metatarsal and metacarpal ash content increased quadratically (P less than .01) as dietary Ca/P increased with suggested dietary breakpoint inflections of .90% Ca and .70% P at 40 kg, and at .72/.55% levels at 57 kg body weight. Percentage ash of the head portion of the bone was lower than the shaft section. Bone shaft thickness and bending moments for metatarsals and metacarpals increased as dietary Ca/P levels increased, with higher values and higher dietary inflection points at 57 than at 40 kg body weight. Bone length was not influenced by dietary Ca/P level, but fat-free dried bone weight was, resulting in higher total bone ash and organic weight as Ca/P level increased.     

Dietary calcium and phosphorus for lactating swine at high and average production levels

An experiment utilizing 198 first-and 77 second-litter sows evaluated the effects of five dietary Ca:P levels at two litter sizes (six to seven or 11 to 12 pigs/litter) over a 21-d lactation period for two parities. Lactation dietary P levels ranged from .50 to .90% in .10% increments with Ca concurrently increased in a 1.3:1 ratio using dicalcium phosphate and limestone as the inorganic mineral sources. A 14% protein, corn-soybean meal diet was formulated with .80% Ca and .60% P for gestation while lactation diets varied in their Ca and P contents. Randomly selected sows from each treatment group and parity were slaughtered with various bones collected for analyses. A counterpart set of nongravid gilts remained on trial and were slaughtered at the end of the two-parity period with bones collected. Sow dietary mineral level did not affect sow or pig performance, nor was there an interaction between dietary mineral level, parity or litter size nursed. Serum and milk Ca, P or Mg were unaffected by dietary Ca:P at 7 or 21 d of lactation, but milk Ca and P increased from parity I to II. Percent rib and vertebra bone ash decreased from parity I to II for sows nursing the larger litters; other bones were unresponsive to dietary mineral level. Femur thickness decreased from parity I to II but was not influenced by dietary Ca:P level. Bone-bending moment of the ribs, metacarpals and metatarsals were not influenced by diet, but a lower metacarpal bending moment was observed for sows nursing larger litters. All bones from nongravid females had higher percentage of bone ash, bending moment and shaft thickness when compared with reproducing sows. These results suggest that reproductive state (i.e., reproducing vs non-reproducing), litter size and parity affected sow Ca:P mineral skeletal reserves more than dietary Ca:P levels.     

Effect of dietary calcium and phosphorus level sequences on performance, structural soundness and bone characteristics of growing-finishing swine

The effects of feeding various dietary Ca:P level sequences on gain and feed efficiency, leg structural soundness and bone indices of growing-finishing swine were evaluated as an incomplete 3 X 3 factorial arrangement of treatments in a split-plot design. A total of 664 pigs were fed one of three total dietary Ca:P levels (.52:.40, .65:.50, .80:.60%) from 19-kg to 56-kg body weights followed by one of three Ca:P levels (.45:.32, .52:.40, .65:.50%) to market weight. The .80:.60% and .65:.50% Ca:P mineral sequence was not evaluated. Diets were formulated to 14.5% crude protein using a corn-soybean meal mixture with proportions of dicalcium phosphate and limestone altered to attain the desired dietary Ca:P levels. Maximum gains occurred at the .65:.50% and .52:.40% Ca:P level during the grower (P less than .01) and finisher (P less than .01) periods, respectively. No grower X finisher phase pig gain or feed intake interaction resulted, providing evidence of no carry-over response on these measurements from the grower to the finisher period. Serum P concentration increased and plateaued at the same dietary Ca:P level, as did rate of gain at both 56-kg and 95-kg body weights. Leg soundness subjectively evaluated at 56-kg and 95-kg body weights revealed no effect of dietary Ca:P level on soundness scores at 56 kg, but at 95-kg body weight, the interaction between grower and finisher diets was significant. Percentage bone ash of the humerus, shaft thickness and bending moment of the femur increased as dietary Ca:P level increased at both 56-kg and 95-kg body weights.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of a bone biopsy technique for determining the calcium and phosphorus status of swine from weaning to market weight

Tibia biopsies were taken from 75 live pigs at 4-wk intervals and from 251 slaughtered pigs to evaluate bone biopsy as a procedure for determining Ca/P status in pigs fed 70, 85, 100, 115 and 130% of the NRC (1979) estimated dietary Ca and P percentage requirements from weaning to market. Least squares means and SE of live and slaughter biopsy wet weight, ash weight and dry, fat-free ash percentage (DFF%) were compared at each time in each trial and found not to differ. Diet and time effects on ash weight, ash percentage of wet weight and DFF% of the biopsy core also did not differ greatly between slaughter and live biopsies and generally responded linearly and quadratically (P less than .01) to increasing Ca/P level and time. Biopsy measures were correlated (P less than .05) with third and fourth metacarpal and metatarsal length, bending and shear stress and DFF%. Means for slaughter biopsy DFF% did not differ greatly from the average of third and fourth metacarpal and metatarsal DFF% from slaughter pigs. Means for live and slaughter biopsy DFF% were lower than those for whole bones for the 70 and 85% NRC estimated Ca/P levels, but not for the 100, 115 and 130% NRC levels. Bone biopsy offers potential as a reliable noninvasive procedure for monitoring Ca/P status of swine from weaning to market, but it needs further study for use in Ca/P research in swine.     

Body weight of young broilers fed with declining calcium and phosphorus contents during the starter period is irresponsive to changes in the skeleton

To evaluate the effect of reduced calcium (Ca) and available P (aP) levels in starter diets on growth performance and tibia, sternum and serum characteristics, and to assay the association between Ca and P (aP) intakes and these variables, 600 one-day-old broiler chicks (Ross 308) were used in a 21-days trial. Broilers were randomly allotted to five treatments with five replicate pens. Chicks were fed on one of the five starter diets that were formulated with a 10% reduction in the Ca and aP contents, starting from the control diet and hence, named as C (0.96% Ca, 0.45% aP), L1 (0.85% Ca and 0.42% aP), L2 (0.77% Ca and 0.38% aP), L3 (0.68% Ca and 0.34% aP) and L4 (0.61% Ca and 0.31% aP). Declining dietary Ca and aP levels did not affect body weight and levels of Ca, P and alkaline phosphatase in serum, but reduced linearly feed intake, the feed conversion ratio and the bone weight and ash content. The Ca and aP intakes and Ca:aP ratio displayed a positive correlation with both tibia and sternum weights, and the mass of the bones were equally sensitive to dietary Ca and aP levels. In conclusion, the body weight of young broilers was irresponsive to changes in the skeleton when exposed to early dietary Ca and aP restrictions (up to 0.61% Ca and 0.31% aP) and the mechanostat had limits due to the association between Ca and aP intakes, and bone properties.     

Calcium and phosphorus requirement of swine from weaning to market weight: II. Development of response curves for bone criteria and comparison of bending and shear bone testing

Three trials involving 251 crossbred pigs were conducted to establish response surfaces for effects of Ca/P levels (70, 85, 100, 115 and 130% of NRC [1979] estimated requirements) and time (weaning to market) on bone criteria and to compare bending and shear bone testing. Nine replicates, each consisting of five pigs, were used over the three trials. One pig per replicate was slaughtered every 4 wk following the start of the trials. Third metacarpals and metatarsals (3M) and fourth metacarpals and metatarsals (4M) were collected at slaughter; the bone length, bending or shear stress, and dry, fat-free ash percentage (DFF%) were determined. Most bone criteria increased (P less than .01) at a decreasing rate (P less than .05) in response to increasing dietary Ca/P intake and increased linearly (P less than .01) with time on test, although bone length and stress increased at a decreasing rate with time on test. Asymptotic models relating continuous effects of total Ca + P intake ratio (CAP; expressed as a percentage of NRC) and number of days on test before slaughter to bone measurements were fit to least squares slaughter time by diet means. Bone length and DFF% reached 98% maximum at or near 100% the NRC estimated CAP level; however, to reach 98% of maximum bone shear and breaking stress higher CAP levels were required. Shear testing of bones was more desirable than bend testing as a method of determining bone strength due to reduced variability, better discrimination of Ca/P and time effects and ease of calculation.     

Evaluation of phytase concentration needed for growing-finishing commercial turkey toms

1. Growth performance, serum bone markers, and bone strength and mineralisation were determined in tom turkeys grown from 9 to 17 weeks of age. 2. Dietary non-phytate phosphorus was formulated to be reduced by 1.0 g/kg in the low phosphorus diet compared to a control diet and phytase was added to provide 0, 150, 300, 450 or 600 units/kg activity to the low phosphorus diet. 3. From 9 to 12 weeks of age, body weight and gain:food were reduced by the low phosphorus diet without added phytase, compared to the adequate phosphorus diet. Increasing the concentration of phytase linearly increased these growth parameters. There were no significant growth responses at 17 weeks of age. 4. Serum osteocalcin was reduced by increasing dietary phosphorus at 12 weeks of age when growth was affected, but not at later ages. Serum pyridinoline was reduced by higher dietary phosphorus and decreased linearly with increasing phytase activity at 17 weeks of age. 5. Fracture force of the ulna and femur increased linearly with increasing phytase activity but bone strength was not affected when corrected for bone cross-sectional area. Bone strength of the ulna and ash concentration of the ulna and tibia were increased by higher dietary phosphorus. Humerus and ulna ash increased linearly with increasing phytase activity. 6. Water-soluble phosphorus content of the litter was increased by higher dietary phosphorus and addition of phytase to the low phosphorus diet. The increase in water-soluble phosphorus content of the litter when phytase was fed may indicate that phosphorus could be fed at a lower concentration than used in this trial, at least in the finisher diet when phytase is added to the food. 7. Bone fracture force, strength and ash were generally optimised when 450 units/kg phytase activity was added to the low phosphorus diet. However, growth performance was best in the grower I (9 to 12 weeks) phase when 600 units/kg phytase was added to the diet.     

Interactive effects of sodium zeolite-A and copper in growing swine: growth, and bone and tissue mineral concentrations.

An experiment was conducted with 64 crossbred pigs to determine the effect of 0 or .50% dietary sodium zeolite-A (NZA) in combination with 0 or 250 ppm supplemental Cu (as CuSO4.5H2O). Pigs were assigned randomly to one of the following four treatments: 1) corn-soybean meal basal (B), 2) B + .50% NZA, 3) B + 250 ppm Cu, or 4) B + .50% NZA + 250 ppm Cu. Each treatment was replicated four times with four pigs per replicate. Average initial weight was 7.5 kg and the experimental period lasted 144 d. Overall rate and efficiency of gain, incidence of gastric ulcers, dressing percentage, carcass weight, percentage of muscling, 10th rib fat, loin eye area, blood urea N, and bone Ca, P, Mn, Fe, Ni, Na, and Al concentrations were not affected by treatment. The addition of 250 ppm Cu increased liver (P less than .01), serum (P less than .06), and bone (P less than .07) Cu concentrations but decreased mean backfat thickness (P less than .09), bone ash percentage (P less than .03) and serum (P less than .09) and bone (P less than .01) Zn concentrations. Sodium zeolite-A increased serum alkaline phosphatase (P less than .04), carcass length (P less than .06), and liver (P less than .02) and bone (P less than .01) Zn content but decreased (P less than .04) serum Ca and serum inorganic P concentrations. Sodium zeolite-A did not protect against liver Cu accumulation or gastric ulceration in growing swine fed 250 ppm supplemental Cu.     

Effect of dietary calcium level and source on mineral utilisation by piglets fed diets containing exogenous phytase

Calcium and phosphorus are essential minerals, closely linked in digestive processes and metabolism. With widespread use of low P diets containing exogenous phytase, the optimal dietary Ca level was verified. The 40‐day study evaluated the effects of Ca level (4, 7 and 10 g/kg diet) and Ca source (Ca from CaCO₃ and from Lithothamnium calcareum) on mineral utilisation in 72 piglets (7.9 ± 1.0 kg BW) fed an exogenous phytase containing diet with 2.9 g digestible P/kg. Measured parameters were growth performance, stomach mineral solubility, bone breaking strength and urinary, serum and bone mineral concentration. The apparent total tract digestibility of minerals was also assessed in the two diets with 7 g Ca/kg, using 12 additional pigs. Regardless of Ca source, increasing dietary Ca impaired feed conversion ratio, increased urinary pH, increased serum and urinary Ca, decreased serum and urinary P, decreased serum Mg and increased urinary Mg, increased serum AP activity, decreased bone Mg increased bone Zn. Bone breaking strength was improved with 7 compared to 4 g Ca/kg. Compared to CaCO₃, Ca from Lithothamnium calcareum increased serum Mg and with, 10 g Ca/kg, it limited body weight gain. The dose response of Ca in a diet with 2.9 g digestible P/kg and including exogenous phytase indicated that: (i) a low dietary Ca was beneficial for piglet growth, but was limiting the metabolic use of P; (ii) a high dietary Ca level impaired P utilisation; (iii) the optimal P utilisation and bone breaking strength was obtained with a dietary Ca‐to‐digestible P ratio of 2.1 to 2.4:1; (iv). Increasing dietary Ca reduced Mg utilisation, but not Zn status, when fed at adequate level. Finally, Ca from Lithothamnium calcareum had similar effects on Ca and P metabolism as CaCO₃, but impaired growth when fed at the highest inclusion level.     

Effect of dietary fluorine on growth, blood and bone characteristics of growing-finishing pigs

Three hundred eighty-four growing-finishing pigs were used in two experiments to determine the effect of dietary fluorine (F) on growth, blood and bone physical characteristics. Fourteen dietary treatments were formulated by supplementing F (as NaF) to a milo-soybean meal basal diet (7 ppm F) to provide levels of 7, 132, 257, 382, 507 and 632 ppm F for Exp. 1, and 7, 25, 43, 61, 79, 97, 115 and 133 ppm F for Exp. 2. Average daily gain (ADG) and average daily feed intake (ADFI) were not affected (P greater than .09) when F was fed at levels between 7 and approximately 132 ppm. Average daily gain and ADFI were reduced (P less than .0001) for pigs consuming diets with F concentrations greater than 132 ppm (Exp. 1). Feed conversion was not affected (P greater than .17) by any level of F fed. Serum F and alkaline phosphatase concentrations increased (P less than .01) with increasing dietary F levels. Serum and bone Ca and P concentrations were not affected (P greater than .13) by dietary F levels (Exp. 1). In Exp. 1 and 2, bone F increased (P less than .0001) and metatarsal stress and modulus of elasticity decreased (P less than .0001) as level of F increased in the diet. Bone thickness decreased quadratically (P less than .02) in Exp. 1 and linearly (P less than .0007) in Exp. 2 with increased dietary F levels. Scanning electron microscopy showed an increase in porosity of bones from pigs fed the higher levels of F. Growing-finishing pigs were able to tolerate approximately 132 ppm F for growth, but all of the F levels (greater than or equal to 7 ppm) fed in these two experiments affected bone integrity.     

Bone mineral response to ammonium sulphate offered as a lick supplement in beef calves

Sixteen Bonsmara calves (4 males, 12 females) between 10 and 18 months of age were blocked according to age and sex and randomly assigned to 2 groups. They were offered licks containing bone meal and salt (50:50 ratio) (control) and bone meal and ammonium sulphate (NH4SO4) at 1.25, 2.5, 5, 10, 15, and 18% (treatment) to evaluate the effects of dietary anions on bone phosphate (P) concentration. Bone P concentration was significantly (P < 0.05) higher in the NH4SO4 group compared with the control group, indicating that NH4SO4 was able to increase the P content of bone at each of the 6 concentrations used in the lick relative to the control animals, thereby improving the P status of the animals. Ammonium sulphate at 15% and 18 % in the lick also significantly (P < 0.05) increased bone P compared with the lower concentrations of NH4SO4. Bone calcium (Ca) fluctuated as a result of the acidogenic lick. There was absorption of Ca when P was being resorbed and resorption of Ca when P was being absorbed into and out of bone. Bone Ca:P ratio ranged from 3.2 to 6.4 among the control group and 1.6 to 4.3 among the treatment group. Animals receiving the acidogenic lick had a higher percentage ash compared to the control group for most of the experimental period. Bone magnesium (Mg) fluctuated in response to the acidogenic lick, and it was difficult to show a relationship between bone Mg and Ca or P. The overall mean cortical bone thickness was significantly (P < 0.05) greater in treatment (1.60 mm) compared with control (1.43 mm) calves and this was also true at sampling periods 2, 4, 5 and 6. Bone thickness followed bone P and not bone Ca. Results from this research indicate that the addition of ammonium sulphate to a lick had a beneficial effect in improving the P status by increasing bone P and improving the mineral status of bone by increasing the thickness of cortical bone and percentage ash.     

Calcium and phosphorus utilisation in chickens fed on diets high in N-alkane-grown yeast

Interactions between calcium (Ca) and phosphorus (P) were studied in young chickens fed on diets high in n-alkane-grown yeast and in chicks fed on control soya-fishmeal diets for 14 d. Additions of inorganic Ca to diets containing 300 g yeast/kg caused increases in body-weight gain, gain:food ratio and bone mineralisation up to a total dietary concentration of 13.9 g Ca/kg. At all additions of Ca, bone mineralisation was inferior in yeast-fed chicks compared with control chicks. Supplementation of high Ca diets (16.8 g Ca/kg) with inorganic P led to further improvements in body-weight gain, food intake and food utilisation of chicks fed on high-yeast diets. Bone mineralisation also improved but was always inferior in the yeast-fed chicks compared with control chicks. It was concluded that Ca and P supplementation was necessary in high-yeast diets due to low dietary Ca concentrations and low availability.     

Dietary calcium-phosphorus ratios for growing pigs in relation to serum levels and bone development

Two experiments comprising a total of 80 Danish Landrace pigs in the period 20–90 kg live-weight were carried out to study the effect of dietary levels and ratios of Ca and P on serum values of Ca, inorg. P, and alkaline phosphatase and on the development of degenerative arthritis and atrophic rhinitis.In both experiments each kg feed (Table 1) was supplemented with 600 i. u. vitamin D₃ and 80 p. p. m. Zn.In the first experiment the Ca:P ratio was 1.2 and the amount of Ca increased from 0.48 % to 1.20 % without influencing daily gain, feed conversion, carcass performance (Table 2) or frequency of atrophic rhinitis (Table 3). The Ca:P ratio in scapula was 2.15. Only when the diet was supplemented with 1.20 % Ga and 1.00 % P the bone quality was histomorphologically adequate (Figs. 1–4).In the second experiment various Ca:P ratios (ranging from 0.1 to 3.0) were compared with the recommended level and ratio of 0.72 % Ga and 0.60 % P. Performance of pigs on the normal level was better than for the other pigs (Table 4). Clinically, various degrees of leg-weakness and -deformation occurred, most pronounced in the high Ca — low P group. Very little lameness and no convulsions were observed. Marked hypocalcemia was not found. Unilateral high Ca intake increased serum Ca significantly, and serum alkaline phosphatase slightly, and decreased serum P (Figs. 5–7). Advanced pericytic osteolysis, poor mineralization and generalized osteodystrophia fibrosa were found in the low Ca groups (Figs. 8–13). The groups showed no differences in frequency of atrophic rhinitis (Table 5), and rickets was not observed.The incidence of degenerative joint lesions was not increased in pigs on the unfavourable Ca:P ratios, and depended apparently more on litters than on diets.     

Effects of dietary calcium, available phosphorus and vitamin D on growth rate, food utilisation, plasma and bone constituents and calcium and phosphorus retention of commercial broiler strains

1. The effects of different dietary concentrations of calcium (Ca), available phosphorus (AP) and vitamin D (D) on 5- to 16-day growth performance, and aspects of calcium and phosphorus (P) metabolism of chickens from three commercial strains were studied in two experiments. 2. Increasing dietary Ca reduced weight gain, tibia Ca and P content and increased plasma total Ca, Ca consumption and excretion, whilst dietary Ca at 32 g/kg increased tibia Ca:P ratio, plasma ionized calcium and reduced plasma P, tibia ash, P excretion, excreta moisture and Ca retention. 3. Increasing dietary AP reduced plasma total and ionized Ca and excreta moisture and increased P consumption and excretion, plasma P and tibia ash. 4. The addition of vitamin D increased plasma total and ionized Ca, tibia Ca:P ratio and reduced plasma sodium and P concentrations. 5. Strains differed in their tibia contents of Ca and Ca:P ratios, in response to Ca, AP and vitamin D diets whilst they differed in Ca excretion and excreta moisture caused by feeding either dietary Ca or AP. 6. It was concluded that dietary Ca, AP, vitamin D and strain of broiler chickens influenced the metabolism of Ca and P and that, as a consequence, the tolerance to high dietary Ca. A lean strain of chickens tolerated high dietary calcium better than its fat counterparts.     

Influence of dietary phosphorus level on growth performance in chicks given corn-soybean diet supplemented with amylase and acid protease

Two experiments were conducted to determine if dietary amylase and acid protease supplementation improves the nutritive value of corn-soybean diet, and whether the dietary inorganic phosphorus (P) level affects the growth-promoting effect induced by the enzyme supplementation in chicks. In the first experiment, 4-day-old Single Comb White Leghorn male chicks were given a corn-soybean diet supplemented with amylase and acid protease for 10 days. Dietary amylase addition produced a significant improvement in growth and food efficiency, whereas acid protease had no effect on these parameters. Although there was no significant interaction between amylase and acid protease, the combination of the two enzymes produced the greatest improvement in growth performance. In contrast, neither enzyme influenced the metabolizable energy value or nitrogen balance. In the second experiment, chicks were given corn-soybean diets having low, medium and high levels of inorganic P (3.5, 4.3 and 5.1 g/kg, respectively), supplemented with both enzymes. There were significant interactions between the dietary inorganic P level and enzyme supplementation on final bodyweight, bodyweight gain and food intake. Enzyme supplementation significantly improved chick growth at the medium inorganic P level, but not at the low or high levels. Although the thigh bone ash content and serum P concentration were improved as the dietary inorganic P level increased, enzyme supplementation had no influence on these parameters. In conclusion, the present results indicate that dietary amylase and acid protease have beneficial effects on growth performance in chicks given corn-soybean diet. The dietary inorganic P level affects the growth response to dietary amylase and acid protease supplementation.     

Physiological effects of feeding high levels of magnesium to sheep

The effects of feeding high levels of Mg to sheep on animal health, nutrient digestibility, metabolism of macro-minerals, blood and tissue mineral concentrations and hematological and histological tissue changes were evaluated. Six lambs were allotted to each of four diets supplemented with MgO to attain .2, .6, 1.2 or 2.4% Mg. Total fecal and urinary collections were made for the initial 20 d and last 10 d of a 50 d study. Diarrhea was noted in lambs fed the two highest Mg levels. Apparent digestibility of DM, ADF and CP decreased linearly (P less than .01) with increasing Mg levels. Dietary Mg levels did not affect (P greater than .05) rectal temperature, respiration rate or pulse rate. Apparent absorption and retention of Mg (g/d) were lowest in lambs fed 2.4% Mg until 15 d on trial, after which values increased linearly (P less than .01) with dietary Mg. Phosphorus absorption and retention decreased linearly (P less than .01) with increasing Mg levels. Increasing dietary Mg resulted in a linear increase (P less than .01) in serum Mg and variable increases (P less than .05) in erythrocyte Mg. Serum Ca was decreased linearly (P less than .05) and quadratically (P less than .05) by added Mg during the d 1 to 30 and 40 to 50 periods, respectively. Serum inorganic P was elevated consistently in lambs fed 2.4% Mg. A linear response to increasing dietary Mg (P less than .05) occurred in the Mg content of liver, kidney, rib bone and femur bone. Dietary Mg did not alter (P greater than .05) other criteria.(ABSTRACT TRUNCATED AT 250 WORDS)     

内蒙古牧区察哈尔羔羊饲粮钙磷适宜水平研究

本试验采用4个不同钙磷水平的饲粮饲喂断奶后察哈尔羔羊,研究钙磷对断奶羔羊生长、钙磷营养消化代谢和排放量、骨骼的影响。选取70日龄健康、体重(16.27±3.33) kg断奶察哈尔羔羊120只(公母各半),随机分成4个组,每组30个重复,每个重复1只羊,分别饲喂4种饲粮,其钙磷含量分别为:Ⅰ组,0.49%、0.28%;Ⅱ组,0.55%、0.32%;Ⅲ组,0.64%、0.47%;Ⅳ组,0.87%、0.70%。饲养试验期65 d,其后,每组选6只羔羊(公母各半),全收粪法进行消化代谢试验。试验结果:1)饲粮钙磷水平对断奶羔羊平均日增重、体尺、干物质采食量和饲粮转化率影响皆不显著(P>0.05);2)血清钙含量Ⅳ组显著高于其他3组,血清碱性磷酸酶Ⅰ组显著高于其他3组(P<0.05);3)Ⅰ组钙表观消化率显著高于其他3组(P<0.05),随饲粮钙磷水平升高羔羊钙磷排放量增加(P<0.05);4)Ⅳ组胫骨灰分含量显著高于Ⅰ组(P<0.05),Ⅰ组跖骨灰分含量显著低于Ⅲ、Ⅳ组(P<0.05),胫骨磷含量Ⅳ组显著高于其他3组(P<0.05);5)冬春季节改变羔羊饲喂模式增加了内蒙古地区草原生态系统中钙磷的输入。综上所述,饲粮钙磷水平升高降低了断奶羔羊的钙表观消化率,显著增加了钙磷的排放量,提高了羔羊骨骼钙磷沉积。在本试验条件下,饲粮钙磷含量分别为0.49%、0.28%,内蒙古地区冬春季断奶羔羊即可获得较好的生长性能。     

Influence of ingestion of aluminum, citric acid and soil on mineral metabolism of lactating beef cows

Lactating beef cows (16 Hereford and 34 Angus, 430 kg average body weight, aged 8 to 10 yr) were fed a basal diet containing 200 micrograms/g Al alone or supplemented with Al-citrate, citric acid, soil or soil plus citric acid for 56 d. Diets containing Al-citrate, soil and soil plus citric acid contained 1,730, 1,870 and 1,935 micrograms/g Al, dry-basis, respectively. Adding soil to the diet also increased Mg and Fe content of the diet. Aluminum values in ruminal contents of beef cows fed the basal alone or supplemented with citric acid, Al-citrate, soil or soil plus citric acid were 800, 990, 2,930, 3,410 and 2,910 micrograms/g, air-dry basis, respectively. Serum Mg and inorganic P declined (P less than .01) and urinary Ca concentration increased (P less than .01) for cows fed Al-citrate. By d 56, serum Mg was 1.5 and 2.2 mg/dl, and serum P was 3.8 and 6.8 mg/dl, for cows fed Al-citrate and basal diets, respectively. Calcium concentrations in urine were 281 and 11 micrograms/g for cows fed Al-citrate and basal diets, respectively. Citric acid, soil and soil plus citric acid had no detrimental effects on serum Mg and inorganic P, or urinary Ca concentration. By d 56, serum Ca was higher (P less than .06) in cows fed Al-citrate, compared with cows on the other four diets. Bone Ca, P, Zn and percent ash were not significantly affected by treatment but bone Mg tended to be slightly lower (P less than .07) for cows fed Al-citrate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary calcium:phosphorus ratios on apparent absorption of calcium and phosphorus in the small intestine, cecum, and colon of pigs

Thirty-two crossbred barrows were used to investigate the effects of dietary Ca:total P (tP) ratios in phytase-supplemented diets on the apparent absorption of P and Ca in the small intestine, cecum, and colon. Three Ca:tP ratio treatments (1.5:1, 1.3:1, or 1.0:1) were created by adjusting the amount of ground limestone added to the basal low-P grower (.39% tP including .07% added inorganic P) and finisher (.32% tP without added inorganic P) diets. All low-P ratio diets were supplemented with Natuphos phytase at 500 units/kg. A positive control diet without phytase supplementation contained adequate P and Ca to meet dietary requirements. At 123 kg, the pigs were slaughtered and the contents of ileum, cecum, and colon were collected. Lowering the dietary Ca:tP ratio in the diets containing phytase linearly increased (P < .01) the apparent absorption (% and g/d) of P in the small intestine, but Ca absorption was not affected. Pigs fed the low-P diet with a Ca:tP ratio of 1.0:1 had an apparent absorption (g/d) of P or Ca similar to that of pigs fed the control diet, which was adequate in Ca and P. Averaged across all diets, the apparent absorption of P was highest when measured at the cecum, and the apparent absorption of Ca was highest when measured at the colon. In conclusion, lowering the dietary Ca:tP ratio to 1.0:1 in a low-P diet containing phytase increased the apparent absorption of P in the small intestine. Furthermore, a significant amount of P was absorbed in the cecum.