Determination of the digestible energy intake and apparent absorption of macroelements in pasture-fed lactating Thoroughbred mares

AIM: To measure the nutritive value of pasture in terms of digestible energy (DE) intake (DEI) and dry matter (DM) digestibility, and to determine the apparent absorption of macroelements in lactating Thoroughbred mares grazed on pasture. METHODS: DM intake (DMI) and DEI were determined from daily faecal DM output measured in grazing mares, divided by the DM indigestible fraction (1-digestible DM), measured in a digestibility trial using pasture-fed mares. Eight lactating mares and their foals, that had a mean age of 40 days, were grazed separately on 50x100 m areas of pasture and daily faecal DM outputs were recorded for 8 days. Five mares and their foals were then placed in individual bare 20x20 m corrals containing custom-made feeding stations for 14 days to determine the indigestible DM fraction. DM, gross energy content, crude protein (CP), soluble carbohydrate, acid detergent fibre (ADF), neutral detergent fibre (NDF), lipid, and macroelement composition of the pasture offered and faeces were determined and their digestibility and/or apparent absorption calculated. RESULTS: DM digestibility of the pasture was 0.6 and the DMI and DEI of a grazing 560 kg mare in early lactation nursing a foal growing at 1.34 kg/day was 13.6 (SE 0.8) kg/day and 146.9 (SE 8.4) MJ DE/day, respectively. Apparent absorptions of the macroelements measured were: Ca 0.75, P 0.43, Mg 0.63, Na 0.78, and K 0.72. CONCLUSIONS: Good quality ryegrass-white clover pasture that had a DE content of 10.8 MJ/kg DM, and a macroelement composition (g/kg) of Ca 3.33, P 3.0, Mg 1.67, Na 1.67, and K 24.2, will provide adequate DMI, DEI, and macroelement intake to lactating Thoroughbred mares.     

Serum and ruminal fluid characteristics of beef cows grazing oat pastures and supplemented with or without lasalocid

Thirty-two mature, pregnant beef cows (avg age 8 yr, body wt 550 kg) grazing oat pastures were used to determine the effects of lasalocid on serum mineral and ruminal fluid volatile fatty acid (VFA) concentrations. Cows were blocked by breed type and assigned randomly to eight, 2-ha pastures containing oat forage from December 17, 1985 to May 6, 1986. The cows were fed .25 kg of ground corn with or without 200 mg of lasalocid daily. Based upon analyses of forage mineral composition (.53, .25, .14, .3 and 2.5% of dry matter for Ca, P, Mg, Na and K, respectively), all macrominerals except Mg were in sufficient quantities to meet the requirement for lactating cows. Lasalocid supplementation did not affect serum Mg, K or Zn concentrations (P greater than .05). During the April sampling, serum Ca was higher (P less than .05) and serum Na was lower (P less than .05) in cows supplemented with lasalocid compared with controls. The molar proportion of acetate was decreased (P less than .05) in ruminal fluid of cows fed lasalocid by d 56 (February 11); the molar proportions of acetate and butyrate were decreased (P less than .05), which decreased (P less than .05) the acetate: propionate ratio by d 84 (March 11) of supplementation. This study suggests that lasalocid is effective in altering ruminal VFA and serum mineral concentrations in cows grazing small grain forages.     

Mineral Content of Forages Grown on Poultry Litter-Amended Soils

Large quantities of poultry litter are applied each year to pastures in Arkansas and Oklahoma. Our objective was to monitor mineral concentrations in forages grown on poultry litter-amended soils and compare them with mineral requirements for gestating and early lactating beef cows. A total of 65 forage samples were gathered from four farms in northwest Arkansas and northeast Oklahoma from April 2000 to March 2002. Mean forage mineral concentrations were compared with beef cattle requirements using a two-tailed t test. Two-year average forage Ca, P, K, S, and Fe concentrations from each farm exceeded (P<0.05) gestation and lactation requirements, but forage Zn concentrations from one farm did not differ (P>0.05) from gestation and lactation requirements. On individual sampling dates, concentrations of Ca, P, K, and Zn rarely fell below lactation requirements. Mean forage Mg concentrations from one farm exceeded (P<0.05) lactation requirements, but those from the other three farms exceeded (P<0.05) gestation but not (P>0.05) lactation requirements. Mean tetany ratios from all farms were below (P<0.05) the tetany threshold of 2.2, but forage from two farms surpassed the tetany threshold during Spring 2000, and one sur-passed it during Spring 2001. Average forage Cu concentrations were below (P<0.05) requirements on one farm and did not differ (P>0.05) from the requirements on three farms. Forages from pastures fertilized with broiler litter may meet most but not all mineral requirements of beef cattle, and supplementation of specific minerals, particularly Mg and Cu, may be necessary.     

Mineral Status and Interrelationship in Soil,Forage, and Blood Serum of Horses in the Rainy and Dry Seasons

The objective was to evaluate the content of P, Ca, Mg, K, Na, Cu, Fe, Zn, Se, and Mn in soil, forage, and serum of horses in several production units (PU) during rainy and dry seasons and predict their concentration in serum from their content in soil and forage. Soil and pastures were sampled in the dry (November–December) and in rainy seasons (June–July), and blood samples were collected from the jugular vein of 76 horses in both seasons at four PU. The experimental design was a completely random design within a 4 × 2 (PU × season) factorial arrangement of treatments. Concentration of minerals in soil differed (P < .05) among PU, and contents of P, Ca, Mg, and K were low; Zn and Fe were high; and Cu and Mn were adequate. Mineral concentrations in forage differed among PU and season, and among PU within season (interaction P < .05). Contents of Ca, Mg, Na, Zn, and Cu were low; Fe was high; and P, K, Se, and Mn adequate. The mineral concentration in equine blood serum differed (P < .05) among PU and season. Overall, there were deficiencies of P, Ca, Mg, Na, Cu, and Se, but adequate amounts of K, Zn, and Fe. There are imbalances of minerals in soil and forages which effected their concentration inequine blood.     

几种优良人工牧草矿质元素含量的比较研究

就地上部而言,在3种豆科牧草中,白三叶以N、P、K、Fe、Co、Na含量较高,红三叶以Mg、Zn含量较高。在3种禾本科牧草中,鸭茅以P、K、Mg、Mn、Cu、Zn、Mo含量较高,草地早熟禾以Fe较高。3种豆科牧草N、Ca、Mg、V、Sr的平均含量显著高于禾本科牧草。地上部与地下部比较,豆科牧草的P、K、Ca、Mn、Zn、Na含量前者显著高于后者;禾本科牧草的N、P、K、B含量,前者明显高于后者。     

Effect of pre-calving zeolite, magnesium and phosphorus supplementation on periparturient serum mineral concentrations

The objective of this study was to test whether supplementing dry cow rations with phosphorus (P) and magnesium (Mg) would interfere with the beneficial effect of zeolite supplementation on the periparturient blood calcium (Ca) concentration in dairy cattle. Three groups (A-C) of 10 Danish Jersey cows were each given the following daily supplements from 2 weeks before the expected date of calving until actual calving: group A: zeolite, monoammonium phosphate, standard dry cow mineral and vitamin mix, containing 61g magnesium phosphate; group B: zeolite, standard mineral and vitamin mix without the magnesium phosphate and group C: standard mineral and vitamin mix, monoammonium phosphate. All cows in group B had an apparently less variable serum calcium concentration around calving with no cases of milk fever and no subclinical hypocalcaemia or hypomagnesaemia recorded. In contrast, a parturient drop in blood Ca was seen in group A as well as group C. In group A, one cow was hypocalcaemic at calving, and developed milk fever. In group C, 12 blood samples, representing six cows, were hypocalcaemic, and three of these cows were treated for milk fever. All groups remained normomagnesaemic and there were no significant differences in blood Mg across groups. In conclusion, the combined P and Mg supplementation in addition to zeolite supplementation did not increase the serum Mg level (forage Mg 16.9g/day; 0.21% of DM). Combined P and Mg supplementation reduced the zeolite-induced hypophosphataemia but also reduced the stabilising effect of zeolite on parturient serum Ca.     

Effect of soil type and fertilization level on mineral concentration of pasture: potential relationships to ruminant performance and health

A three-year study was conducted to measure the effects of varying levels of dairy slurry application on mineral concentration of forages from three soils types. Slurry was applied to orchardgrass (Dactylis glomerata [L.] cv. Pennlate) growing in 60-cm diameter drainage lysimeters to measure the effect of four levels of slurry (urine and feces) N application (0, 168, 336, and 672 kg of N.ha-1.yr-1) on mineral (P, K, Ca, Mg) concentration of the forage on three soil types (Hagerstown, Hartleton, and Rayne). The results were then related to potential effects on performance and health of grazing ruminants. Forage P was not affected by slurry application (mean = 0.46% of DM). Forage grown on the Hartleton soil had the highest (P < 0.05) P concentration (0.6% of DM). Forage K increased (P < 0.05) with increased slurry (2.50, 2.85, 3.22, and 3.45% of DM, respectively), and was lowest (P < 0.05) for forage grown on the Rayne soil (2.69% of DM). Forage Ca decreased (P < 0.05) with increased slurry (0.59, 0.56, 0.50, and 0.49% of DM, respectively) and was not affected by soil type. Forage Mg also decreased (P < 0.05) with increased slurry (0.25, 0.24, 0.24, and 0.23% of DM, respectively), and was highest (P < 0.05) for the Hartleton soil (0.27% of DM). The variable results in mineral concentration associated with soil type may have, in part, been due to prior soil fertility. The P and Mg concentrations in all treatments were generally adequate for grazing ruminants. The K concentrations were high in relation to NRC recommendations for prepartum dairy cows, which might predispose them to milk fever. The Ca concentrations were inadequate for lactating dairy cows. Comprehensive forage testing and diet formulation based on individual farm situations is the best strategy to ensure proper mineral nutrition of grazing animals.     

四川阿坝县秋季牧草钙磷等矿物元素特征及其与土壤钙磷含量的关系

采用常规方法测定了四川阿坝县4个不同牧场秋季(9月)牧草矿物元素含量及土壤中的钙磷含量,以期为该地区反刍动物的放牧饲养提供依据。结果表明:阿坝县4个地区秋季牧草矿物元素中钙、钠和锌的含量差异不显著,磷、铁、铜、钾、镁、锰和硒含量差异显著(P<0.05),其中磷、锌和硒的含量不能满足反刍家畜的营养需求,需要补饲;土壤中钙含量差异不显著,全磷和有效磷差异显著(P<0.05);牧草中的钙、磷含量与土壤中钙、磷含量之间没有显著的相关性。     

Influence of milk production potential on forage dry matter intake by multiparous and primiparous Brangus females

Brangus cows (n = 29) were used in three experiments to evaluate the effects of parity (multiparous vs. primiparous) and potential genetic merit for milk production (high vs. low) on forage intake during late gestation, early lactation, and late lactation. Cows were selected for milk production based on their sire's EPD for milk production (MEPD). Cows had ad libitum access to (130% of previous 2-d average intake) low-quality hay (5.3% CP and 76% NDF), and cottonseed meal was supplemented to ensure adequate degradable intake protein. All females were adapted to diets for at least 7 d, and individual intake data were collected for 9 d. During the lactation trials, actual milk production was determined using a portable milking machine following a 12-h separation from calves. During late gestation, multiparous cows consumed 24% more (P = 0.01) forage DM (kg/d) than primiparous cows; however, parity class did not influence forage intake when intake was expressed relative to BW. Furthermore, MEPD did not influence forage intake during late gestation. During early lactation, multiparous cows produced 66% more (P < 0.001) milk than primiparous cows, and high MEPD tended (P = 0.10) to produce more milk than low MEPD. Multiparous cows consumed 19% more (P < 0.0001) forage DM than did primiparous cows when expressed on an absolute basis, but not when expressed on a BW basis. High-MEPD cows consumed 8% more (P < 0.05) forage DM than did low-MEPD cows. During late lactation, multiparous cows produced 84% more milk than primiparous cows, although MEPD did not influence (P = 0.40) milk yield. In addition, multiparous cows consumed 17% more (P < 0.01) forage DM per day than primiparous cows, but when intake was expressed relative to BW, neither parity nor MEPD influenced forage DMI during late lactation. Milk yield and BW explained significant proportions of the variation in forage DMI during early and late lactation. Each kilogram increase in milk yield was associated with a 0.33- and 0.37-kg increase in forage DMI for early and late lactation, respectively. Results suggest that multiand primiparous cows consume similar amounts of low-quality forage DM, expressed per unit of BW, during late gestation and lactation. Selecting beef cows for increased genetic merit for milk production increases forage DMI during early lactation.     

Effects of supplementation on intake, digestion, and performance of beef cattle consuming fertilized, stockpiled bermudagrass forage

Experiments were conducted to determine the effects of increasing supplement protein concentration on performance and forage intake of beef cows and forage utilization of steers consuming stockpiled bermudagrass forage. Bermudagrass pastures were fertilized with 56 kg of N/ha in late August. Grazing was initiated during early November and continued through the end of January each year. Treatments for the cow performance trials were: no supplement or daily equivalents of 0.2, 0.4, and 0.6 g of supplemental protein per kilogram of BW. Supplements were formulated to be isocaloric, fed at the equivalent of 0.91 kg/d, and prorated for 4 d/wk feeding. Varying the concentration of soybean hulls and soybean meal in the supplements created incremental increases in protein. During yr 1, supplemented cows lost less weight and condition compared to unsupplemented animals (P < 0.05). During yr 2, supplemented cows gained more weight (P = 0.06) and lost less condition (P < 0.05) compared to unsupplemented cows. Increasing supplement protein concentration had no affect on cumulative cow weight change or cumulative body condition score change. Forage intake tended to increase (P = 0.13, yr 1 and P = 0.07, yr 2) in supplemented cows. Supplement protein concentration did not alter forage intake. In a digestion trial, four crossbred steers were used in a Latin square design to determine the effects of supplement protein concentration on intake and digestibility of hay harvested from stockpiled bermudagrass pasture. Treatments were no supplement; or 0.23, 0.46, and 0.69 g of supplemental protein per kilogram of BW. Forage intake increased (P < 0.05) 16% and OM intake increased (P < 0.01) 30% in supplemented compared to unsupplemented steers. Diet OM digestibility increased (P = 0.08) 14.5% and total digestible OM intake increased (P < 0.05) 49% in supplemented compared to unsupplemented steers. Supplement protein concentration did not alter forage intake, total digestible OM intake, or apparent digestibility of OM or NDF. During the initial 30 d after first killing frost, beef cows did not respond to supplementation. However, later in the winter, supplementation improved utilization of stockpiled bermudagrass forage.     

Composition and Nutrient Deficiencies of Arkansas Forages for Beef Cattle

A database was compiled to determine the nutrient composition, variability, and nutrient deficiencies of 11,592 forage samples (10,246 hay, 1,001 pasture, and 345 silage) collected from 1985 to 1999. Samples were analyzed for 1 to 15 nutrients: DM, N, ADF, NDF, P, K, Ca, Mg, Na, S, Fe, Mn, Zn, Cu, and Se. Mean (±SD) CP and TDN levels (% DM) of bermudagrass, fescue, and mixed grass (blends of bermudagrass, fescue, orchardgrass, ryegrass, and cheat) hays were 12.4 ± 3.5, 60.0± 6.2; 11.2± 3.0, 53.8± 4.7; and 11.1 ± 3.1, 52.9± 4.7, respectively. For beef cows and calves, TDN was deficient in a greater percentage of hays (P < 0.05) than was CP. Bermudagrass hays contained greater levels of CP and TDN than fescue or mixed grass hays (P < 0.05). Fescue and mixed grass hays did not differ (P > 0.05) in CP, ADF, NDF, or TDN concentrations. Only 6 to 10% of the hays analyzed for Na contained adequate levels for beef cows and calves. Selenium, Cu, and Zn were deficient in 62, 52, and 41% of the hay samples, respectively. For lactating beef cows, a lesser percentage of the hays were deficient in P (16%), Ca (7%), Mg (30%), and S (8%). Iron, Mn, and K were deficient in 2% or less of the hays. Bermudagrass, corn, and sorghum-sudan silages contained greater (P < 0.05) levels of TDN than silages composed of fescue, mixed grass, ryegrass, sorghum silage types, or wheat. With the exception of bluestems and orchardgrass, the pasture samples contained greater concentrations of CP and TDN than the same forage species harvested as hay. In general, forages were highly variable in nutrient content, and most hays were deficient in one or more nutrients for beef cattle.     

Content and distribution of macro- and micro-elements in the body of pasture-fed young horses

OBJECTIVE: To determine the content and distribution of Na, K, Ca, P, Mg, S, Cu, Mn, Fe and Zn in the body of pasture-fed young horses and then use a factorial model to calculate the dietary mineral requirements for growth. PROCEDURE: Twenty-one foals were killed at about 150 days of age and the organs, soft tissues, skin and bones and a sample of muscle were dissected out and weighted. The mineral concentrations of elements in all soft tissues and bones were measured by inductively coupled emission spectrometry. The total mineral element composition associated with a tissue was determined from the weight of tissue and its mineral element concentration. RESULTS: Expressed as a percent of total body mineral elements, muscle contained 20% Na, 78% K, 32% Mg, 62% Cu, 36% Mn and 57% Zn, bone contained 47% Na, 99% Ca, 81% P, 62% Mg, 30% Mn and 28% Zn while the organs accounted for a smaller percentage ranging from 0.06% for Ca to 26% for Fe. In liver Cu accounted for 9.2% of total body Cu. Each kilogram of empty body weight was associated with 1.0 g Na, 2.5 g K, 17.1 g Ca, 10.1 g P, 0.4 g Mg, 1.1 mg Cu, 0.39 mg Mn, 52.5 mg Fe and 21.4 mg Zn. CONCLUSION: The mineral element content of body weight gain is a component used in the factorial model to determine dietary mineral element requirements for growth. The calculated dietary mineral requirements, expressed per kg dry matter, for a 200 kg horse gaining 1.0 kg/day were 1.0 g Na, 2.1 g K, 4.6 g Ca, 3.5 g P, 0.7 g Mg, 4.5 mg Cu and 25 mg Zn.     

粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响

本试验旨在研究粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响。试验采用单因素随机区组设计,将 １６头体重、年龄、胎次相近的,处于干奶期的健康荷斯坦奶牛分为 ４组,每组 ４头。以常用的粗饲料设计 Ａ（玉米青贮 ＋玉米秸秆）、Ｂ（玉米青贮 ＋羊草）、Ｃ（玉米青贮 ＋玉米秸秆 ＋羊草）、Ｄ（玉米青贮 ＋苜蓿草 ＋羊草）４种粗饲料组合的饲粮。结果表明：饲粮Ｄ干物质、有机物和中性洗涤纤维的消化率最高,显著高于其他各饲粮（Ｐ＜０．０５）,其次为饲粮Ｂ和饲粮 Ｃ,饲粮 Ａ最低,显著低于其他各饲粮（Ｐ＜０．０５）,各饲粮的酸性洗涤纤维消化率差异不显著（Ｐ＞０．０５）。粗饲料组合显著影响饲粮摄入总能、能量消化率和能量代谢率（Ｐ＜０．０５）,饲粮 Ｄ甲烷能占摄入总能比显著低于其他 ３种饲粮（Ｐ＜０．０５）。各饲粮的粪氮、尿氮占摄入总氮比差异不显著（Ｐ＞０．０５）,饲粮 Ｄ的氮消化率显著高于饲粮 Ｂ与饲粮 Ｃ（Ｐ＜０．０５）,且饲粮 Ｂ显著高于饲粮 Ａ（Ｐ＜０．０５）;饲粮 Ｂ、饲粮 Ｄ的氮利用率显著高于饲粮 Ａ（Ｐ＜０．０５）。由此可见,玉米青贮 ＋苜蓿草 ＋羊草型饲粮的养分消化率、能量和氮的利用均优于其他各饲粮,羊草与玉米秸秆之间存在正组合效应,两者搭配使用可提高玉米秸秆的消化率,优化能量和氮的利用。     

Mineral assessment in Atriplex halimus L. and Atriplex nummularia L. in the arid region of Jordan

The foliage of Atriplex halimus contained higher levels (P < 0.05) of ash (28.03%) than that of Atriplex nummularia (23.11%). Spring growth of the two saltbushes contained less ash than the fall regrowth. The foliage of A. halimus contained higher levels of macro-minerals than A. nummularia plants except sodium. The two saltbushes contained higher levels of P, K and Mg during spring, but lower levels of Ca and Na compared to the growth of the fall season. Levels of Fe, Cu, Mn and Se present in the foliage of A. nummularia plants were higher than A. halimus. Clipping had no significant effect on ash content of saltbushes, but it affected the composition of the ash significantly. Clipping decreased the concentrations of Ca, P, Na, Mg and Fe in the foliage of clipped shrubs. The mineral composition of the two species of Atriplex appeared adequate to meet the requirements of sheep and goats grazing such types of forage.     

Mineral absorption in the black rhinoceros (Diceros bicornis) as compared with the domestic horse

To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for black rhinoceroses (Diceros bicornis), we investigated the apparent absorption (aA) of macro- and microminerals in eight black rhinoceroses from three zoological institutions in a total of 32 feeding trials with total faecal collection, with additional data from three unpublished studies (18 feeding trials). Feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Mn, Cu, Zn and Co. The resulting aA coefficients, and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content [per 100 g dry matter (DM)], were compared with data for domestic horses. Rhinoceroses had significantly higher aA coefficients for Ca and Mg (because of a higher calculated 'true' absorption), and lower ones for Na and K (because of calculated higher endogenous faecal losses). High absorption efficiency for divalent cations is hypothesized to be an adaptation to a natural diet of particularly high Ca:P ratio (approximately 14:1); an effective removal of Ca from the ingesta guarantees sufficient P availability at the fermentation site in the hindgut. Higher faecal losses of Na and K are hypothesized to be linked to a higher faecal bulk per DM intake in black rhinoceroses as compared with horses because of a generally lower digestive efficiency. There were no relevant differences in the absorption patterns of microminerals. In particular, there were no discernable differences in Fe absorption within the rhinoceroses for diets with and without tannin supplementation. Several of the zoo diets assessed in this study were deficient in Cu, Mn or Zn, and most contained excessive levels of Fe when compared with horse requirements. The findings of this study indicate that differences in mineral absorption between occur even between species of similar digestive anatomy; that in particular, Ca absorption might vary between hindgut fermenters with Ca:P ratio in their natural diet; that Na might be a particularly limiting factor in the ecology of free-ranging rhinoceroses; that moderate doses of tannins do not seem to markedly influence mineral absorption; and that diets for captive animals should contain adequate, but not excessive mineral levels.     

Mineral absorption in tapirs (Tapirus spp.) as compared to the domestic horse

To test whether mineral recommendations for horses are likely to guarantee adequate mineral provision for tapirs (Tapirus spp.), we investigated the apparent absorption (aA) of macro and micro‐minerals in 18 tapirs from five zoological institutions in a total of 24 feeding trials with total faecal collection. Samples of feeds and faeces were analysed for Ca, P, Mg, Na, K, Fe, Cu and Zn. The resulting aA coefficients and the linear relationships of apparently absorbable dietary mineral content to total dietary mineral content (per 100 g dry matter) were compared with data for domestic horses. While there were no apparent differences in the absorption patterns for P, K, Na, Fe, Cu or Zn, the absorption of both Ca and Mg was distinctively higher in tapirs than in horses. Tapirs are browsers that are adapted to a diet of higher Ca content and higher Ca:P ratio than equids, and high absorptive efficiency for Ca might have evolved to ensure that high dietary Ca concentrations do not lead to the binding of dietary P in the intestine, making it unavailable for hindgut microbes. Similar to other hindgut fermenters, in tapirs, absorption coefficients for Ca increased with dietary Ca:P ratio, and urinary Ca:creatinine ratios increased with dietary Ca. Several zoo diets used were deficient in one or more minerals. When compared with faeces of free‐ranging animals, faeces of zoo animals had higher concentrations of most minerals, probably indicating a lesser diluting effect of indigestible fibre in zoo animals.     

不同泌乳阶段奶牛饲料中N、P、Ca的生物学利用率研究

试验选用体况、胎次、产奶量相近的中国荷斯坦新产牛和泌乳高峰牛各6头,分别在第0 d、5 d、10 d测定（估测）各生理阶段奶牛产奶量、饲料采食量和粪尿排放量,同时,采集其饲料、牛奶、粪便和尿样进行N、P、Ca百分含量测定,通过分析饲料、牛奶、粪便和尿中N、P、Ca含量,计算出各泌乳期奶牛N、P、Ca的生物学利用率。结果表明,新产牛对N、P、Ca的表观吸收率分别为77.21%±1.91%、56.08%±8.22%和47.62%±7.47%,表观存留率分别为15.6%±9.70%、12.38%±12.07%和32.5 2%±7.93%;泌乳高峰牛对N、P、Ca的表观吸收率分别为76.37%±3.08%、60.15%±8.54%和49.58%±9.89%,表观存留率分别为18.26%±6.35%、23.65%±9.57%和36.56%±10.96%。新产牛对N、P、Ca的表观吸收率与泌乳高峰牛对N、P、Ca的表观吸收率之间均无显著差异（P〉0.05）,而对N、P、Ca的表观存留率,泌乳高峰牛均高于新产牛。     

Evaluating the effect of calcium,magnesium and sodium supplementation of Merino ewes on their lambs' growth

Our study aimed to investigate responses to supplementation of calcium (Ca), magnesium (Mg) and sodium (Na) to lactating ewes and lambs grazing barley forage from lamb marking to weaning. A 10-ha paddock sown to barley was subdivided into eight plots as four replicates of two treatments. Merino ewes (n = 104) with lambs at foot were stratified to the eight plots (13 ewes and 21 lambs/plot) based on number of lambs (twin or single) and ewes' weight. Supplemented groups had access to mineral supplements (30 g/ewe/day) supplying 12 g/ewe/day ground limestone, 12 g/ewe/day Causmag® and 6 g/ewe/day coarse salt in a ratio of 2: 2: 1 by weight (as fed) from day 0 (a day before lamb marking) after sample collection. Control groups were not supplemented with minerals. Blood, milk and urine samples from ewes and blood from lambs were collected at different time points, namely, a day prior to lamb marking (day 0), 14 days after the commencement of study (day 14), and 28 days after the commencement of study (day 28). Weight of the lambs was also recorded at each time point. We found that the concentration of the forage minerals (Ca, Mg and potassium (K)) was lower on day 28 than on day 0 (P < 0.025). Liveweight gain was greater in the first 14 days compared with the second weight gain period (P < 0.001). The interaction of time and treatment was significant for liveweight (P < 0.001). Due to the improvement in weight gain of supplemented lambs, we recommend that mineral supplementation during late lactation is beneficial considering the low cost of minerals, even though the mineral content of the forage was not deficient.     

Mineral intake and hair analysis of horses in arizona

To evaluate the effect of diet on hair mineral content, 61 feeds, 31 pasture grasses, 29 mineral supplements, 31 water samples and hair samples from 391 horses from 31 ranches in Arizona were analyzed for fifteen minerals. Based on dietary histories and estimated intakes when free choice access was involved, mineral intake of the horses was calculated and compared to mineral content of the hair. Data were evaluated by regression analysis for correlations between hair and dietary minerals and variations in hair mineral content attributable to coat color, age, sex and breed.¹¹,¹²,¹³,¹⁴

There were differences (P<.05) in hair mineral content of horses of different breeds, coat colors, ages and sex, regardless of dietary intake. However, there were some significant correlations between feed mineral intake and hair mineral content. A few weak simple correlations (Ca:Ca, P:P, Na:Na, K:K) were found, but complex mineral correlations (Ca:P, Ca:Na, Zn:K, Fe:Zn etc.) were more common and had higher correlation coefficients (Table 7). Variations in mineral intake explained only 30% of the variation for a given hair mineral, with the exception of manganese. The multiple relationships between minerals and their effect on metabolism appear to have a greater effect on hair mineral content than a single mineral deficiency or excess¹⁷,¹⁸,²⁰,²¹ and may offer better insight to the interpretation of mineral nutrition than simple one to one correlations.     

小麦麸水平对生长鸡钾、钠、钙、镁及磷利用的影响

试验观察小麦麸水平对生长鸡常量元素利用的影响。试验以去皮去胚玉米、玉米淀粉及提纯大豆蛋白为主的半纯合型饲粮,分别含有0(对照)、8、16、24、32及40％的小麦麸,添加玉米油降低饲粮能量差异。测定钾、钠、钙、镁及磷在某些组织的沉积量及真利用率。试验结果表明钾、钠、钙、镁及磷的利用均受饲粮小麦麸的影响,这种影响主要表现在排泄物中元素含量的增加,以及真利用率的降低。钾、镁及磷的采食量随小麦麸水平的提高而显著增加(P<0.001),排泄物中含量也随之显著增加(P<0.001),小麦麸含量从8％升至40％,钾、镁及磷的含量分别增加1.0—6.1、1.0—4.9及1.4—2.8倍,真利用率分别降低(P<0.01)16.2—76.7％、19.6—53.5％及13.1—42.9％。钙和钠的采食量在饲粮间变化较小,8—40％小麦麸导致钙排泄量增加(P<0.01)41.5—733.2％,40％小麦麸导致钠含量增加31.1％(P<0.05)。小麦麸含量为8—40％,钙的真利用率降低9.9—19.8％(P<0.01),钠真利用率降低13.6—34.9％,小麦麸含量高于24％差异显著(P<0.05)。血液和肝脏中元素的沉积量不受小麦麸的影响。小麦麸含量为8—40％,胰脏中钾含量降低(P<0.01),小麦麸含量超过24％,胫骨中钙含量降低7.3—1 4.3％(P<0.05),小麦麸超过40％,胫骨磷含量降低10.5％(P<0.05)。