Trace Mineral Source Research Articles

Effects of Trace Mineral Supplementation, Source, and Growth Implants on Immune Response of Growing and Finishing Feedlot Steers

<h2>ABSTRACT</h2> To determine the effects of growth implants and trace mineral (TM) supplementation and source on immune response, 375 steers (approximately 7 mo of age and 250.0 ± 11.0 kg), stratified by initial body weight, were randomly assigned to 1 of 36 pens that were then randomly assigned to treatments. Treatments consisted of 1) control (no supplemental Cu, Zn, Mn, and Co), 2) inorganic TM (CuSO₄, ZnSO₄, MnSO₄, and CoCO₃), and 3) organic TM (iso-amounts of organic Cu, Zn, Mn, and Co). On d 28 post-arrival to the feedlot, steers from 6 pens per treatment received a growth implant containing 200mg progesterone and 20mg estradiol benzoate, whereas the other half of the steers within the same treatment (6 pens) did not receive a growth implant. Steers were fed a corn silage-based growing diet for 56 d and were then gradually switched toa high-concentrate finishing diet. At the beginning of the finishing phase, only steers receiving growth implants during the growing phase were reimplanted with 80mg of trenbolone acetate and 16mg of estradiol. During the finishing phase, all minerals excluding Zn were fed at NRC recommended concentrations in inorganic form. Treatments during the finishing phase consisted of 1) control (no supplemental Zn), 2) inorganic Zn (30mg Zn/kg DM from ZnSO₄), and 3) organic Zn (iso-amounts of organic Zn). At the end of the growing phase, steers receiving organic TM had greater (P < 0.02) total IgM concentrations than inorganic-supplemented steers, and implanted steers tended (P < 0.07) to have greater IgG antibody titer concentrations specific for pig red blood cells than nonimplanted steers. During the finishing phase, steers supplemented with organic Zn had greater (P = 0.04) ovalbumin antibody titer concentrations than steers supplemented with inorganic TM.Superoxide dismutase activity, interferon gamma concentrations, and antibody titers specific to pig red blood cells and infectious bovine rhinotracheitis virus were unaffectedby TM treatment or growth implants.

Effects of Copper and Zinc Source on Performance, Carcass Characteristics, and Lipid Metabolism in Finishing Steers

An experiment was conducted to determine the effects of Cu and Zn source on performance, trace mineral status, lipid metabolism, and carcass quality of finishing steers. In the study, 195 steers were blocked by origin, stratified by BW, and sorted into 24 pens. Pens within blocks were then randomly assigned to treatments in a 2 × 2 factorial arrangement. Factors were 10 mg of Cu/kg of dietary DM from CuSO4 or 10 mg of Cu/kg of dietary DM from organic Cu and 90 mg of Zn/kg of dietary DM from ZnSO4 or 36 mg of Zn/kg of dietary DM from organic Zn with 54 mg of Zn/kg of DM from ZnSO4. Steers were fed a high concentrate finishing diet until they reached an approximate BW of 580 kg. Diets were fed once daily in the morning to allow ad libitum access to feed throughout the day. Daily feed offerings were recorded and feed refusal was measured every 28 d. Body weights were recorded for each steer and blood samples were collected from 3 steers per pen every 28 d. Three weeks prior to slaughter, subcutaneous adipose tissue biopsies were taken from 1 steer per pen. Postharvest longissimus dorsi muscle samples were collected and evaluated for fatty acid composition. There were no Cu or Zn main effects or Cu × Zn interactions for ADG, DMI, or feed efficiency. The effect of Cu or Zn source was similar across treatments for hot carcass weight, dressing percent, rib eye area, subcutaneous fat thickness, kidney, pelvic, and heart fat, and marbling score. There was a Zn effect for calculated yield grade. Steers receiving organic Zn had a lesser (P = 0.03) calculated yield grade than steers receiving inorganic Zn. Serum cholesterol, plasma Cu and Zn concentrations, fatty acid composition of longissimus muscle and subcutaneous fatty acid synthase activity were similar across treatments. Results from this study indicate that trace mineral source had little influence on performance, carcass characteristics, and lipid metabolism.

Effects of Trace Mineral Supplementation and Source, 30 Days Post-weaning and 28 Days Post Receiving, on Performance and Health of Feeder Cattle

Three hundred and seventy-five steers (approximately 7 mo of age and 239.0±10.4 kg) were utilized to determine the effects of trace mineral (TM) supplementation and source on performance during the on-farm backgrounding and feedlot receiving phases of beef cattle production. At their respective ranches, steers were stratified by body weight into six groups. Groups were then assigned to one of six pens and pens were randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu, Zn, Mn, and Co), 2) inorganic trace mineral (CuSO 4 , ZnSO 4 , MnSO 4 , and CoCO 3 ), and 3) organic trace mineral (iso-amounts of organic Cu, Zn, Mn, and Co). Mineral treatments were fed in alfalfa pellets formulated to supply 360 mg of Zn, 200 mg of Mn, 125 mg of Cu, and 12.5 mg of Co per head per day from either organic or inorganic trace mineral sources. Control steers received alfalfa pellets with no additional Cu, Zn, Mn, or Co. Steers were allowed free access to harvested alfalfa-grass hay throughout the 30-d on-farm backgrounding phase. On day 30 post-weaning, steers were weighed and transported to the feedlot. Steers were blocked by treatment within ranch, stratified by initial body weight, and randomly assigned to one of 36 pens (9-12 head per pen; 12 pens per treatment). Steers remained on the same on-farm backgrounding trace mineral treatments, however, trace mineral treatments were included in the total mixed growing ration. Steers were fed a corn silage-based growing diet throughout the 28 d feedlot receiving period. There was no effect of TM supplementation on performance of steers during the on-farm backgrounding phase. By the end of the 28-d feedlot receiving phase, ADG was similar between control and trace mineral supplemented steers. Steers supplemented with organic TM had greater (p<0.05) ADG than steers supplemented with inorganic TM by the end of the 28-d feedlot receiving phase. Morbidity and mortality rates were similar across treatments.

The Effect of Trace Mineral Fortification Level and Source on Performance of Dairy Cattle

Five hundred seventy-three cows, balanced by parity and 305-d mature equivalent at dry off, were assigned to 1 of 4 treatments: 1) 75% complexed trace minerals (CTM; 75C): Zn, Mn, Cu, and Co supplied at 75% of NRC (2001) guidelines by Zn-, Mn-, and Cu-specific AA complexes, and cobalt glucoheptonate; 2) 100% inorganic (100I): Zn, Mn, Cu, and Co supplied at 100% of NRC (2001) requirements by sulfate sources; 3) 100% complexed (100C): Zn, Mn, Cu, and Co supplied at 100% of NRC (2001) requirements by CTM; and 4) complexed/ inorganic (C/I): Zn and Cu supplied at 100% of NRC (2001) requirements using a combination of CTM and sulfates and Co and Mn supplied with sources at 9.1 and 3.3 times NRC (2001) requirements using a combination of CTM and sulfates. All percentages of Zn, Cu, Mn, and Co relative to NRC (2001) reflect supplemental contributions and do not include basal diet contributions. Experimental periods were dry period 1, full lactation 1, dry period 2, and 200 d into the subsequent lactation. Reproductive, health, and production information was collected during both lactations. Claw evaluations were conducted at trial start, 150 d into lactation 1, at the end of lactation 1, and 150 d into lactation 2. During lactation 1, C/I cows produced more milk, fat-corrected milk, energy-corrected milk, and fat than 100I cows. During lactation 2, yields of milk, fat-corrected milk, energy-corrected milk, fat, and protein were higher for 100C and C/I cows than for 75C or 100I cows. Fat percentage was highest for 100C cows with no treatment effect on protein content. During lactations 1 and 2, C/I cows had fewer days to first estrus than cows receiving the other treatments. During lactation 2, C/ I cows had fewer services per conception and days open. There were no significant effects of treatment on health. White line separation incidence was lower for 100I cows than 75C cows, whereas heel erosion was higher for the 100I cows than for the C/I cows. Fortification of trace elements with inorganic and complexed sources at or above NRC requirements improved reproductive and productive performance. In addition, cows can be supplemented with CTM at 75% of NRC requirements with no reduction in performance compared with supplementing at 100% of NRC requirements using only sulfate sources of Zn, Mn, Cu, and Co.

Efeito da suplementação dietética com micro minerais orgânicos na produção de galinhas poedeiras

Um experimento foi realizado para avaliar os efeitos da suplementação dietética de fontes orgânicas de microminerais na produção de ovos de galinhas poedeiras. Foram utilizados 8 tratamentos: um com todos os minerais na forma inorgânica, um com todos na forma orgânica e mais 6 tratamentos com apenas um dos minerais na forma orgânica. Os minerais testados foram: zinco, manganês, iodo, selênio, cobre e ferro. As dietas experimentais foram à base de milho e farelo de soja. Foram utilizadas 672 aves da linhagem ISA Babcock B 300, o período de experimentação foi de 48 a 60 semanas de idade, e os parâmetros de desempenho produtivo avaliados foram: Consumo de ração, produção de ovos, massa de ovos e Conversão Alimentar. Os dados foram analisados em ciclos de postura de 28 dias. A adição dos diferentes minerais isolados ou em combinação, na forma orgânica ou inorgânica, aparentemente não resultou em melhora nas medidas de desempenho, pois à exceção do terceiro período de avaliação, quando obteve-se um menor índice de massa de ovos para o tratamento em que foi empregado o ferro orgânico (p&lt;0,05), não se detectou diferença significativa. Partindo-se da premissa de que as fontes orgânicas de minerais apresentam maior biodisponibilidade, o efeito de seu uso permanece controverso, pois os resultados do experimento sugerem que a suplementação com minerais orgânicos não altera o desempenho da produção de ovos de galinhas entre 48 e 60 semanas de idade, quando comparado com a suplementação inorgânica dos mesmos.

Effects of Mineral Source on Growth and Balance in Yearling Horses1

Sixteen Quarter-Horse yearlings were used in a split-plot designed experiment to evaluate the response of growth and mineral balance to trace mineral source. Horses were blocked by sex and BW and randomly assigned to either an inorganic (ING) or organic (ORG) treatment. Diets were formulated to contain supplemental levels of Zn, Cu, Mn, and Co at four times NRC (1989) recommendations for yearlings in rapid growth. Diets were fed at 2% of estimated final BW and consisted of a pelleted concentrate, Marshall ryegrass hay, and alfalfa cubes fed in a 50:30:20 ratio, respectively. Three 72-h total fecal and urine collections were conducted on d 7, 30, and 60. Blood was taken on d 1 of each total collection to measure serum mineral (Zn and Cu) concentrations. Although mineral digestibility and balance data were not consistent across periods, significant increases in Cu (Period II) and Co (Periods II and III) digestibility and balance were observed for the ORG treatment. These increases indicate that ORG trace minerals may be more available for absorption as compared with IN sources, although excessive supplementation of trace minerals in the diet may obscure differences because of trace mineral source. Thus, the feeding of ORG trace minerals may improve trace mineral absorption, subsequently improving balance and digestibility.

Effect of copper, zinc, and manganese supplementation and source on reproduction, mineral status, and performance in grazing beef cattle over a two-year period.

Crossbred, multiparous beef cows (n = 178 in Year 1; n = 148 in Year 2) were used to evaluate the effects of Cu, Zn, and Mn supplementation and source on reproduction, mineral status, and performance in grazing cattle in eastern Colorado over a 2-yr period. Cows were stratified by expected calving date, age, BW, BCS, and liver mineral status and assigned to the following treatments: 1) control (no supplemental Cu, Zn, or Mn); 2) organic (ORG; 50% organic and 50% inorganic Cu, Zn, and Mn); and 3) inorganic (ING; 100% inorganic CuSO4, ZnSO4, and MnSO4). Free-choice mineral feeders were used to provide current NRC-recommended concentrations of Cu, Zn, and Mn from 82 d (Year 1) and 81 d (Year 2) before the average calving date of the herd through 110 d (Year 1) and 135 d (Year 2) after calving. At the end of Year 1, supplemented cows had greater liver Cu (P < 0.01), Zn (P < 0.05), and Mn (P < 0.01) concentrations compared with controls, whereas liver Cu concentration was greater (P < 0.01) in ORG vs. ING cows. At the end of Year 2, supplemented cows had greater (P < 0.01) liver Cu concentrations relative to controls, whereas control cows had greater (P < 0.02) liver Mn concentration than did supplemented cows. In Year 1, pregnancy rate to AI in control cows did not differ (P = 0.47) from supplemented cows, but there was a trend (P < 0.08) for pregnancy rate to be higher for ORG than ING cows. In Year 2, supplemented cows had a higher (P < 0.02) pregnancy rate to AI than controls. In both years, when cows were inseminated after an observed estrus, supplemented cows had a higher (P < 0.04) pregnancy rate than did controls. Also, for both years, overall 60-d pregnancy rate tended (P = 0.10) to be higher for supplemented cows than for controls. In Year 1, kilograms of calf weaned per cow exposed was greater (P < 0.02) in controls than in supplemented cows, and kilograms of calf weaned per cow exposed was greater (P < 0.01) in ING than ORG treatments. However, in Year 2, kilograms of calf weaned per cow exposed was greater (P < 0.02) in controls than in supplemented cows, and tended (P = 0.09) to be greater in ORG than ING treatments. Results indicate that supplementation and source of trace minerals affected mineral status and kilograms of calf weaned per cow exposed in grazing beef cows. Supplementation also improved pregnancy rate to AI compared with cows not supplemented with Cu, Zn, or Mn for more than 1 yr. Furthermore, mineral source may influence pregnancy rate to AI.

Effect of dietary trace mineral concentration and source (inorganic vs. chelated) on performance, mineral status, and fecal mineral excretion in pigs from weaning through finishing.

Two hundred and sixteen weanling gilts (6.65+/-0.08 kg) were used to determine the effects of decreasing supplemental concentrations of Zn, Cu, Fe, and Mn, and trace mineral source (inorganic vs. chelated) on growth performance, mineral status, and fecal mineral concentrations from weaning through development. The study was conducted over three trials with 72 pigs in each trial. Gilts were blocked by weight and randomly assigned to either 1) control, 2) reduced inorganic, or 3) reduced chelated trace minerals. The control diet was supplemented with 25, 150, 180, and 60 mg/kg of Cu, Zn, Fe, and Mn (in sulfate forms), respectively, during the nursery phase and 15, 100, 100, and 40 mg/kg of supplemental Cu, Zn, Fe, and Mn, respectively, during the growing and gilt-developer phases. Reduced inorganic and reduced chelated treatments were supplemented during all phases with 5, 25, 25, and 10 mg/kg of Cu, Zn, Fe, and Mn, respectively. The reduced chelated treatment supplied 50% of the supplemental Cu, Zn, Fe, and Mn in the form of metal proteinates, with the remainder from sulfate forms. Performance by control pigs did not differ from pigs fed the reduced trace mineral treatments during the nursery and grower-development periods. Gain:feed was lower (P < 0.05) for pigs fed the reduced inorganic compared with those fed the reduced chelated treatment during the nursery period. Trace mineral source did not affect performance during the growing or gilt-developer phase. Plasma Zn concentration and alkaline phosphatase activity were higher (P < 0.01) in control pigs than in those receiving reduced trace minerals during the nursery and growing phases. Plasma Cu concentration and ceruloplasmin activity were generally not affected by treatment. Hemoglobin concentrations were lower (P < 0.05) for the reduced inorganic compared with the reduced chelated treatment in the nursery phase. Fecal concentrations of Cu, Zn, and Mn were lower (P < 0.05) in pigs fed reduced trace minerals than in controls during all production phases. Fecal Zn concentration during the nursery and fecal Cu concentrations during the growing and gilt-developer phases were lower (P < 0.05) in pigs fed the reduced chelated compared with the reduced inorganic treatment. Results indicate that reducing the concentrations of Zn, Cu, Mn, and Fe typically supplemented to pig diets will greatly decrease fecal mineral excretion without negatively affecting pig performance from weaning through development.

Effects of Trace Mineral Source and Feeding Method on the Productivity of Grazing Braford Cows

Braford cows (n = 160) were used to evaluate the effects of trace mineral source and feeding method on cow herd productivity over 3yr. In yr 1, cows were stratified by age and randomly allocated to one of eight groups (n = 20 cows per group). Cows were allotted to 8 of 16 bahiagrass pastures (8.0ha each, one empty pasture between groups) and were rotated each week. Cow groups remained intact throughout the study with the exception of culled cows, which were replaced with 3-yr-old pregnant heifers. Cows were offered 2.27kg of liquid molasses daily from early November until mid April. One mature Braford bull was placed into each cow group starting in early January, where the bull remained for 90 d. Bulls were rotated through cow groups each week. Two main factors were randomly applied to groups in a 2 × 2 factorial arrangement (two groups per treatment): 1) trace mineral source (inorganic vs organic) and 2) mineral feeding method (free-choice vs control-fed in a molasses supplement). Cow BW, body condition score (BCS), pregnancy rate, calving interval, and calf BW at weaning were obtained. Mineral intake was measured each week in pastures where mineral source was provided for ad libitum intake. In yr 1 and 2, liver biopsy collections were conducted for the determination of mineral status at the start and end of winter supplementation on the same six randomly chosen cows. Cows assigned to free-choice treatments consumed 23% less (P<0.001) mineral compared with control-fed cows, resulting in a greater (P<0.05) decrease in liver Zn (yr 1) and liver Cu (yr 2) concentration compared with control-fed cows. Mineral source and feeding method had no effect on cow BW, cow BCS, and calf BW at weaning. Young cows (3 and 4yr of age) consuming organic minerals had a greater pregnancy rate during yr 2 (P<0.05) and 3 (P=0.15) and a lesser (P<0.05) calving interval in yr 1 and 3, compared with cows consuming inorganic minerals. The supplementation of organic minerals (Cu, Zn, Mn, and Co) appears to increase the reproductive performance of young, but not mature, grazing Braford beef cows consuming molasses-based supplements.

Effects of Concentration and Source of Trace Minerals on Performance, Immunity, Mineral and Lipid Metabolism, and Carcass Characteristics of Beef Steers

Two hundred seventy-nine steers were blocked by initial BW, stratified by estimated breed, and randomly assigned to pens and treatments within weight replication. Mineral treatments administered during the receiving phase consisted of Cu, Zn, Mn, and Co administered at the following levels: 1) two times the NRC (1996) recommendation from amino acid complex Availa-4® (Zinpro, Eden Prairie, MN); 2) at the NRC recommendation from Availa-4®, 3) three times the NRC recommendation from inorganic minerals, or 4) six times the NRC recommendation from inorganic minerals. Steers were gradually switched from a moderate to high concentrate corn-alfalfa diet. Finishing phase mineral treatments consisted of 1) mineral treatment from Availa-4® fed at NRC recommendations, 2) mineral treatment from Availa-4® fed at one and one-half times the NRC recommendation, 3) minerals from inorganic sulfate sources fed at one and one-half times the NRC recommendation, or 4) minerals from inorganic sulfate sources fed at three times the NRC recommendation. Eight pens from each treatment were harvested after being fed for a period of 198 or 230 d. Average daily feed intake was reduced (P<0.0001) in steers receiving the inorganic mineral supplementation at six times the NRC recommendation from d 0 to 28. Overall feed efficiency was improved (P<0.01) with the inorganic supplementation at three times the NRC recommendation compared with the organic treatment at the NRC-recommended level. Hepatic Cu stores increased (P<0.0001) with elevated concentrations of Cu in the diet. Overall antibody titer response to bovine rhinotracheitis (IBR) was not different (P>0.05) between treatments. Steers on the organic mineral treatment at one and one-half times the NRC recommendation had greater (P<0.05) C18:1 cis and C18:2 cis-9 trans-11 fatty acids in the longissimus than did steers receiving the inorganic mineral supplement at one and one-half times the NRC recommendation. These results indicate that trace mineral concentration and source had minimal effects on performance and immunity. However, it appears that mineral source may alter lipid metabolism in steers.

Effects of Feeding Complexed Zinc, Manganese, Copper, and Cobalt to Late Gestation and Lactating Dairy Cows on Claw Integrity, Reproduction, and Lactation Performance

Three hundred multiparous Holstein cows (150 cows per treatment) were blocked according to calving date and randomly assigned to a study to determine the effect of trace mineral source on incidence and severity of claw lesions, reproduction, and lactation performance of dairy cattle. Treatments were 1) all trace minerals supplied by sulfates(ITM)or 2) 360mg Zn from Zn amino acid complex, 200mg Mn from Mn amino acid complex, 125mg Cu from Cu amino acid complex, and 12mg Co from Co glucoheptonate per day(CTM;Availa®; Zinpro Corporation, Eden Prairie, MN) replacing an equivalent amount of Zn, Mn, Cu, and Co from sulfates. Cows received assigned treatments from 21 d prior to calving through 250 d of lactation. Cows fed CTM produced 1.2kg more (P < 0.05) milk, energy-corrected milk, and 3.5% fat-corrected milk than cows supplemented with ITM. The CTM treatment reduced (P < 0.05) days open by 22 d and tended to increase (P < 0.15) percentage of cows pregnant by 150 d in milk (54.8% vs 42.7%) and first service conception rate (27.4% vs 18.4%). Cows fed CTM tended to have a lesser incidence (P < 0.15) of claw disorders than cows fed inorganic trace minerals at 75 d postpartum (23.6% vs 34.1%) and numerically lower incidence at 250 d postpartum (10.0% vs 17.7%). The CTM treatment increased yield of milk, decreased days open, and tended to increase first service conception rates, increase percentage of cows pregnant at 150 d in milk, and decrease claw disorders at 75 d postpartum.

Effects of Organic Trace Mineral Supplementation on Sows' Reproductive and Neonates' Growth Performance through 2 wk Postweaning

A feeding trial using sows and their neonates was conducted to determine the effects of source and level of organic trace mineral supplementation on reproductive performance of sows and the subsequent performance of their neonates through 2 wk post weaning. A total of 16 gestating sows (Landrace×Yorkshire) in parities 2 to 4 were randomly assigned to 4 dietary treatments following a 2×2 factorial arrangement in a completely randomized design. One of the two factors evaluated the effect of the source (inorganic vs organic), and the second factor evaluated the effect of the level (low vs high) of trace minerals added to the diet. The trace mineral premixes were formulated to provide a low concentration of trace minerals (50 ppm Fe/87.5 ppm Fe, 17.5 ppm Cu/85 ppm Cu, 45 ppm Zn/60 ppm Zn, and 20 ppm Mn/17.5 ppm Mn), and a high concentration of trace minerals (100 ppm Fe/175 ppm Fe, 35 ppm Cu/170 ppm Cu, 90 ppm Zn/120 ppm Zn, 40 ppm Mn/35 ppm Mn), when included at 0.20% in sows'/weaned pigs' diets, respectively. The total number born, total born alive and weaned, and the average neonate weight at birth were affected neither by the dietary source nor by the level of trace minerals (p>0.05), but an interaction effect (p<0.05) between the source and level of trace minerals was observed on the average weight at weaning. The neonates from sows fed the low level of organic trace minerals gained weight at an equal rate compared with those farrowed by sows fed the high level of inorganic trace minerals. Sows fed the organic trace minerals nursed their young with milk higher in Fe and Zn (p<0.05) compared with those fed diets with inorganic trace minerals. Consequently, the weaned pigs receiving the organic form of trace minerals tended to grow at a faster rate, consumed less feed and tended to utilize their feed more efficiently (p<0.10). It was further observed that the organic trace minerals significantly increased (p<0.05) Fe contents in the liver and serum, and Zn in the serum and bone. In conclusion, sows and neonates fed the organic minerals at low level showed similar performance compared with those fed the inorganic minerals at high level as specified in this study. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 9 : 1312-1318)

Pregnancy attrition from frozen bovine embryos cloned by nuclear transplantation

Pregnant cows were used in a 2 × 2 factorial arrangement of trace mineral (TM) source and breed to investigate the effect of prenatal and lactating TM source on colostrum and milk quality, calf serum Ig concentrations, and calf weaning BW. Angus (n = 99) and Brangus (n = 100) cows were blocked by BW, BCS, age, and stage of pregnancy (88 ± 2 d before calving) to receive either (1) inorganic minerals (ING, n = 100) with Na selenite and Co, Cu, Mn, and Zn in salt sulfate forms, or (2) organic minerals (ORG, n = 99) with Se-yeast and Co, Cu, Mn, and Zn complexed as proteinates. The TM sources were formulated to meet NRC requirements and delivered based on the manufacturer recommendations. Colostrum and milk components were not affected (P > 0.05) by TM source. Colostrum from ORG cows had greater (P < 0.001) Se and tended to have greater (P = 0.07) IgM concentrations. The ORG calves had greater (P < 0.05) serum IgA at 12 and 24 h and greater IgG 30 d after colostrum consumption than ING calves. Birth weight did not differ (P > 0.05) by TM source; however, weaning BW, ADG, and adjusted 205-d BW were greater (P ≤ 0.05) in ORG compared with ING calves. Organic TM source provided during the last trimester of pregnancy and during lactation increased cow colostrum Ig concentrations and calf absorption of IgA and IgG. Postnatal growth was improved in calves born to dams that were supplemented with organic trace minerals.

Effect of Trace Mineral Level and Source on Cow/Calf Performance and Immune Response

Zinc, copper and manganese are needed for proper production and immune response in the cow/calf herd. A series of experiments were conducted over a period of three years throughout the High Plains region evaluating the role of trace mineral level and source on cow and calf liver trace mineral status, immune response, reproduction parameters and growth.

Follow-up or Weaning Formulas

A high level of success in infant nutrition has been achieved in the United States by breast-feeding as preferred, or by feeding with iron-fortified infant formulas. Minor controversies about feeding choices occur when infants are weaned from an all liquid diet to one containing a variety of solid foods. Weaning is not a single event but a process that takes place throughout a number of months, beginning optimally between 4 and 6 months of age. The nutritional objective is to achieve a varied diet with approximately 35% to 50% of energy coming from sources other than breast milk or infant formula. Variety remains the key to the diet, particularly for infants older than 6 months of age. Solid food must provide an adequate source of iron, trace minerals, and vitamins to replace and supplement those in that portion of breast milk or formula removed from the diet. Breast milk and fortified infant formula continue to be optimal for the milk segment of the diet during the second 6 months of life. The mother may choose to stop breast-feeding for a variety of reasons, however. The Committee on Nutrition has indicated that cow's milk could be substituted in the second 6 months of age provided that (1) the amount of milk calories consumed does not exceed 65% of total calories and (2) the solid food portion of the diet replace the iron and vitamins deficient in cow's milk. Recently "follow-up" feedings (formulas) have been marketed in the United States as they have been in Europe for many years.

Dynamics of Grit Selection and Retention in Captive Mallards

The role of grit selection and retention on mortality rates of captive mallards (Anas platyrhynchos) that had ingested lead shot was evaluated in a series of experiments. The calculated rate of grit retention was determined from the negative exponential relationship between the number of marked grit particles in the gizzard and time. Grit consumption, the primary rate-determining step of grit retention, was significantly (P < 0.01) affected by diet, sex, season, mineral composition, and size of particles. Peak grit ingestion by males occurred in the fall, and in females in spring. Ducks maintained on a corn diet consumed twice as much grit as ducks maintained on commercial duck pellets. When offered grit particles between 0.42 and 4.75 mm in diameter, both sexes selected grit particles between 0.84 and 2.00 mm. In spring, females selected oyster shell and sandstone grits over granite, calcium, and quartzite, whereas males preferred sandstone to all other grit types. J. WILDL. MANAGE. 45(1):64-73 Avian species require grit for food digestion (McIlhenny 1932, Leopold 1933) and as a source of trace minerals (Sadler 1961, Harper and Labisky 1964, Kopishke 1966). Bellrose (1959) reported that the time of lead-shot retention was important in determining the degree of mortality suffered by a group of lead-ingesting individuals. Beer and Stanley (1965) postulated that lead and grit interacted, and when excess grit was ingested it was passed and in some instances took the lead shot with it. Bellrose (1975) stated that the size of the lead particle influenced its rate of passage. The kind of grit (calcium) has been shown to lower the mortality of experimentally dosed mallards (Godin 1967, Longcore et al. 1974). The objectives of this study were to identify the factors affecting grit selection and retention in mallards and the role of grit in shot ingestion and retention. I am indebted to the Max McGraw Wildlife Foundation and the College of Agriculture and Life Sciences, University of Wisconsin, Madison, for financial support. The assistance of the foundation staff and G. V. Burger's help with the manuscript are appreciated. I also thank the faculty and graduate students of the Department of Wildlife Ecology, University of Wisconsin, Madison, for their help and suggestions. In particular I acknowledge the guidance and support of R. A. McCabe. METHODS AND MATERIALS Ten experiments were conducted, 9 of which took place within specially constructed pens designed to prevent access to grit. The pens were 2.4 x 2.4 x 1.5 m, with a floor of woven hardware cloth (1-cm mesh) raised 0.6 m above the ground. Six pens were constructed within 1 large outdoor pen. Sheets of corrugated fiberglass were placed 5 cm beneath the floor and inclined toward the front of each pen so that runoff drained into a collection trough. All pens were equipped with a plastic pool 38 cm deep and 75 cm in diameter. A grit feeder (Sadler 1961) was provided inside each pen. A preliminary study was conducted to obtain variance estimates for the computation of sample sizes and types of marker grit. A sample of 10 ducks/experime tal group was determined to be adequate. The best marker grit was green quartzite. Four grit-particle sizes were used: 10 (2.01-4.76 mm), 20 (0.85-2.00 64 J. Wildl. Manage. 45(1):1981 This content downloaded from 157.55.39.56 on Tue, 18 Oct 2016 04:35:10 UTC All use subject to http://about.jstor.org/terms GRIT SELECTION IN MALLARDS * Trost 65 mm), 30 (0.60-0.84 mm), and 40 (0.43-0.59 mm); size was measured as the largest diameter of the smallest cross-section of each particle. Ducks were banded and randomly assigned to treatment groups. At 48-hour intervals, measurements were made of grit and feed consumed by each experimental group, and fecal material was collected. The pens were then washed to prevent reingestion of any marker grit remaining. Fecal materials were washed into large metal containers and agitated to liquefy the fecal pellets. The effluent was poured off and the sediment dried overnight at 120 C. The dried sediment was then crushed lightly using a mortar and pestle and rewashed. After a final drying the grit was sorted and weighed. During the preliminary experiment, a minimum acclimatization period of 2 weeks was necessary to attain a steady consumption of food and grit. In all subsequent experiments, ducks were acclimated to their pens for 2 weeks prior to

Zinc and copper content of foods used in vegetarian diets

The zinc and copper content of seventy-four foods was determined by atomic absorption spectrophotometry. Each of these foods was reported to have been consumed by practicing vegetarians. Legumes, seeds, nuts, whole grains, hard cheeses, and some nutritional supplements were found to be excellent sources of both zinc and copper. Vegetables, fruits, and their products were generally poor sources of trace minerals, with the exception of seed and bean sprouts. Milk and milk products, including rennetless cheeses, contain small quantities of these minerals. Although many of the foods consumed by vegetarians do contain adequate amounts of zinc and copper, their bioavailability may be limited.

Effect of Dietary Mineral Supplements on Radius Breaking Strength and Egg Characteristics of Caged Layers

Six groups of 60 caged White Leghorn hens each, housed two per cage, were fed a basal corn-soy ration for eleven 28-day periods, or the basal ration supplemented with reagent grade minerals as sources of potassium or magnesium, or with single and combined supplements of two commercial sources of trace minerals, designated A and B. Source A supplied Fe, Cu, and Co with a small amount of choline. Supplement B provided Fe, Cu, Co, Mn, Zn, and I.Breaking strength of the radii in the group whose diet was supplemented with both A and B was significantly greater (P≤.01) then the other treatment groups. Shell weight, shell thickness, and percent shell were improved significantly when a combination of A plus B were present in the basal ration. Shell weight and percent shell were also improved when MgSO4 was present. No statistically significant differences were found in hen-day production, livability or feed efficiency due to treatments.

Soil Ingestion by Cattle on Semiarid Range as Reflected by Titanium Analysis of Feces

Highlight: Soil ingestion was determined for cattle grazing a Bromus tectorum range in southern Idaho by measuring titanium concentrations in animal feces collected at 2-week intervals during the droughty 1973 grazing season. The experiment was based on the premise that titanium, which is abundant in soils, is contained only in small quantities (less than 1 ppm) in plants not contaminated with soil. Fecal-soil values averaged 14%, with values ranging from 3 to 30% of fecal dry matter, increasing as forage availability decreased. Soil ingestion levels were estimated to range from 0.1 to 1.5 kg with a median of 0.5 kgsoillanimal-day. This soil was ingested primarily with the roots of Bromus tectorum, which were often pulled up and consumed with the aboveground plant parts. Dust on leaves and stems accounted for only a small portion of the ingested soil. Measurements of acid-insoluble residue concentration in feces overestimated soil ingestion because of the probable presence of SiOZ of plant origin. Large changes in forage SiOZ concentrations of the diet reduce the effectiveness of this method compared to the Ti method. Ingested soil may be a possible source of trace minerals, pesticides, heavy metals, and radionucleides that may be sorbed to surface soil particles.