Trace Mineral Salt Research Articles

306 Cattle Performance and Forage Nutrients While Grazing an Integrated Crop-Livestock System Compared with Grass Pasture in the Northern Great Plains

Abstract Many integrated crop-livestock system (ICL) studies have been conducted, but few report cattle performance and forage nutrients. Here, we report one year of cattle weight gains for Angus yearling heifers and steers grazing ICL plots (ICL) or tame grass pastures (PAS) in four replicates. Five yearlings (avg. BW 390 ± 26 kg) were randomly assigned to graze each plot while provided ad libitum water and trace mineral salt. Cattle assigned to ICL grazed three crop rotations: 1) corn interseeded with soybean (C/S), 2) spring wheat interseeded with cover crop and 3) cover crop planted into spring wheat from the previous year. Yearlings in ICL were stocked first on green C/S, grazing an average of 60 days. Beginning C/S biomass was 1,827 ± 638 g m−2, yearling end BW was 465 ± 34 kg and ADG 1.28 ± 0.27 kg. Yearlings then grazed residual cover crop growth, averaging additional 42 d grazing while supplemented with a ration of baled cover crop forage, wheat straw, and corn. Ration intake averaged 15.35 ±0.6 kg animal-1 d-1. Final BW of ICL yearlings on cover crops averaged 499 ± 34 kg, ADG of 0.79 ± 0.29 kg. Yearlings assigned PAS were provided 1,911 ± 162 g m−2 at the beginning of grazing for 69 days, had final BW 443 ± 35 kg, ADG of 1.01 ± 0.22. Forage nutrient analyses are reported in Table 1, showing that individual crops are similar in ADF and TDN, but vary in crude protein content. Performance of ICL cattle exceeded that of PAS while on corn and soybean but decreased ICL performance while grazing cover crop was likely due to extreme cold weather at the time of grazing. Nutrient values reported here can be used to plan and predict cattle growth while grazing crop residues instead of pastures.

Alfalfa biotypes with putative enhanced cell wall digestibility and effects on performance of growing beef steers.

Three alfalfa biotypes were chosen based on the presumption that they would be sources of alfalfa herbage that differed in lignin concentration and therefore cell wall digestibility. The hypothesis was that a lesser lignin concentration would result in greater alfalfa neutral detergent fiber (NDF) digestibility and greater beef steer growth performance. The three alfalfa biotypes were HarvXtra (Forage Genetics International), Hi-Gest 360 (Alforex Seeds), and a control alfalfa, LegenDairy XHD (Winfield Solutions LLC). High-moisture wrapped bales were prepared from second-harvest, d 30 crops. Digestibility of NDF was determined using in vitro incubations and a steer digestibility trial. Alfalfa baleage and trace mineral salt were fed to Angus steers (300 kg initial body weight, 4 pens/treatment) in an 83-day growing-phase trial. Alfalfa acid detergent lignin concentrations were 75.6, 71.8, and 63.0 g/kg dry matter (P = 0.34) for LegenDairy, Hi-Gest and HarvXtra, respectively. Based on in vitro total-tract NDF digestibility coefficients, HarvXtra tended (P ≥ 0.09) to have the highest NDF digestibility. Alfalfa biotype affected in vivo apparent total tract digestibility of NDF (P < 0.001) and there was a trend for an effect on acid detergent fiber digestibility (P = 0.051). Hi-Gest and HarvXtra had similar in vivo apparent NDF digestibilities, which were greater than for LegenDairy (P < 0.05). There was no alfalfa biotype effect on daily alfalfa dry matter intake (DMI; P = 0.51) or average daily gain (P = 0.25) by growing steers. The absence of an effect by the novel alfalfa biotypes on DMI by growing steers suggests that the compositional and digestibility differences of the novel alfalfa biotypes compared to LegenDairy were not sufficient to alleviate the limitation of physical fill (if evident) on DMI. If more disparity in cell wall composition and NDF digestibility were to exist between control and reduced-lignin biotypes, then perhaps an advantage in cattle growth performance for a reduced-lignin alfalfa biotype would be detectable.

Impact of Garlic-infused Salt Supplement on Fly Abundance, Salt Intake, and Defensive Behaviors in Grazing Beef Cows

This study evaluated the efficacy of free-choice feeding of garlic-infused salt as an alternative pest-fly control strategy in grazing beef cows. This on-farm study is relevant because pest-fly abundance during the summer can impact performance and may cause welfare concerns on beef cattle operations. Over two consecutive summers, three groups of grazing cows received either a trace-mineral salt (TMS) supplement or a TMS infused with garlic powder (GPTMS). The study assessed the treatment effects on fly abundance, defensive behavior, and salt consumption for each group. All cows grazed similar forage species. Fly abundance and defensive behaviors were evaluated in each group using digital imagery. The results showed no difference (P = 0.34) in monthly salt consumption among groups. There were differences (P &amp;lt; 0.0004) in fly abundance among groups where one GPTMS group had at least 47% fewer flies and 41% fewer defensive behaviors than the TMS groups. On the other hand, another group that received GPTMS in the second year indicated a trend (P = 0.07) in fly abundance from its previous outcomes when the group received the TMS in the first year. These differing results for fly abundance and defensive behavior in the groups that received the GPTMS suggest that the efficacy of this feeding strategy in cattle may be affected by differences in genetic or environmental factors or both. We recommended that future studies consider genomic breed compositions before assigning subjects to different groups. Additional studies are required to investigate the variation in individual supplement intake between treatment groups and whether infusing mineral supplements with garlic powder is associated with similar outcomes as salt.

PSVIII-30 Reduced-lignin alfalfa digestibility and effects on performance of growing beef steers

Abstract Novel alfalfa varieties have been developed to have less lignin by genetic modification, (HarvXtra, Forage Genetics International) and by conventional breeding, (HiGest 360, Alforex Seeds). Second crop (d 29) of these alfalfas and a control, LegenDairy XHD (Winfield Solutions LLC), were harvested as high moisture wrapped bales (45.9–51.6 % DM) at the Arlington Agricultural Research Station (AARS) located near Arlington, WI, on July 5, 2017. The objectives of these experiments were to characterize novel reduced-lignin alfalfa varieties, assess their effects on growth of beef steers, and determine digestibilities using a total fecal collection trial. Treatments were fed ad libitum as alfalfa baleage to 300 kg (initial weight) black-hided beef steers, (n = 72, 4 pens/treatment, 83 d). Steers were fed solely alfalfa baleage and offered a trace mineral salt block by way of fence line feed bunks. Alfalfa lignin values were 7.56, 7.18, and 6.3% DM (P = 0.34) for LegenDairy, HiGest and HarvXtra, respectively. Steers gained 0.94, 1.00, and 1.07 kg hd-1 d-1 (P = 0.25) for LegenDairy, HiGest and HarvXtra, respectively. The same harvested alfalfa was used in a total collection fecal trial with fecal collection bags (Table 1). Numerical differences between alfalfa digestibilities were observed but no significant treatment effects were detected. Total tract NDF digestibilities (TTNDFD) for harvested alfalfas were 33.9, 35.0 and 40.3 % NDF (P = 0.079) for LegenDairy, HiGest and HarvXtra, respectively. Alfalfa lignin concentration differences were not detected through acid detergent-lignin analysis of harvested bales. While the ranking of lignin concentrations, digestibilities, and growth rates followed prevailing logic, alfalfa variety treatment effects were not detected. Experimental designs with greater sensitivity should be implemented in the future.

PSXI-23 Effect of garlic powder on supplement consumption and fly abundance in grazing cattle

Abstract Effective pest-fly control strategies in grazing cattle will increase performance, reduce fly-borne diseases and the associated antimicrobial use. This 2-year project evaluated the effects of feeding garlic-powder to grazing cattle. Fly abundance (FA), average salt consumption (SC) and average fly avoidance behaviors (FAB, such as tail-flicks, head-throws and side-licks) were assessed in three independently-managed crossbred cow-calf groups (total=116 to 183 cow-calf pairs) within a subdivided large pasture. Each group received either salt-garlic-powder (SGP) supplement or salt (ST) only, free-choice. The SGP contained 2.1% and 5% garlic powder, respectively in both years. Fly surveys were conducted between June and September each year (approximately every 3 weeks) on cows (n = 5 to 66) randomly sampled from each group. Post-survey image analyses used digital footage and still-images of lateral views of cows and were used to evaluate resting flies (FA) on the cows and FAB. Majority were horn flies based on resting locations on the cows and close-up images. Statistical analyses were performed using generalized linear models adjusted for Year-effect. There was no treatment effect on average SC (P &amp;gt; 0.22) but the groups that received SGP (59g/hd/day) consumed numerically less salt-supplement than ST group (73g/hd/day). The average FA and average proportion of individuals exhibiting FAB were different (P &amp;lt; 0.04) between overall treatment groups where cows that received SGP had fewer flies (55 vs 125 flies) and less FAB (33% vs 42%) than the control group. However, one group that received SGP was not different (P &amp;gt; 0.2) from the control, suggesting that there may be differential insectifugal outcomes based on other factors. While these results suggest that infusing garlic powder into pasture trace-mineral salt does not significantly affect salt consumption and reduces the overall number of pest-flies across different grazing groups, additional studies are required to validate these findings in drylot conditions.

Effects of low-moisture, sugarcane molasses-based block supplementation on growth, physiological parameters, and liver trace mineral status of growing beef heifers fed low-quality, warm-season forage.

The objectives of the study were to evaluate the growth, physiological parameters, and liver trace mineral status of beef heifers provided low-quality warm-season forage and different forms (meal vs. block) of trace mineral-fortified supplementation. One hundred yearling Nellore heifers were blocked by initial body weight (BW) (184 ± 2.5 kg) and randomly assigned into 1 of 20 drylot pens (5 heifers/pen). Treatments were randomly assigned to pens (5 pens/treatment) and consisted of heifers receiving: 1) a loose meal trace mineral supplement (TM; De Heus Animal Nutrition Industry); 2) free choice access to a low-moisture, cooked sugarcane molasses-based protein block (LMB); 3) isocaloric and isonitrogenous, loose meal protein supplement pair-fed to LMB supplement dry matter (DM) intake (PSPF); and (4) loose meal protein supplement offered at 0.2% of BW (PS). Supplements were formulated to achieve same daily intake of supplemental trace mineral among treatments. Hence, TM supplement was offered at 66.6% of the supplement DMI of LMB heifers. Heifers were offered free choice access to water and ground brachiaria (Brachiaria brizantha) hay from day 0 to 45. Overall average daily gain from day 0 to 45 was the least for TM heifers (P ≤ 0.05) and did not differ among LMB, PSPF, and PS heifers (P ≥ 0.60). Daily hay DMI did not differ among treatments (P ≥ 0.63). Total intake of DM and TDN were least for TM heifers (P ≤ 0.03) and did not differ (P ≥ 0.66) among LMB, PSPF, and PS heifers. Total supplemental intake of crude protein (CP) and rumen degradable protein (RDP) and total intake of CP and RDP (supplement + hay) were least for TM and greatest for PS heifers (P ≤ 0.05), and intermediate for LMB and PSPF heifers (P ≥ 0.70). Effects of treatment × day and treatment were not detected (P ≥ 0.61) for plasma concentrations of insulin-like growth factor 1 (IGF-1), and non-esterified fatty acids (NEFA). Effects of treatment were detected for plasma concentrations of PUN (P = 0.005) and tended to be detected for plasma concentrations of glucose (P = 0.08), which were least for TM heifers (P ≤ 0.03) and did not differ (P ≥ 0.17) among LMB, PSPF, and PS heifers. Trace mineral intake and liver concentrations of all trace minerals did not differ (P ≥ 0.13) among treatments. Hence, the use of LMB supplementation resulted in positive effects on growth without impacting trace mineral status compared to a loose meal trace mineral salt, and similar growth performance and trace mineral status compared to a conventional protein supplementation offered at 0.2% of body weight.

Effects of early experience and alternative feeds on medusahead (Taeniatherum caput-medusae ssp. asperum) intake by sheep

The goals of this study were to test the effects of early experience at grazing medusahead – an invasive unpalatable weed – and the availability of forage alternatives on intake of medusahead later in life by sheep. The study involved two experiments of 10 days each. During Experiment 1, 29 yearling sheep were penned individually in a 2×2 factorial design with early experience at grazing medusahead (yes [n=15], no [n=14]) and alfalfa hay availability (yes, no) as the main factors. All animals were fed ad libitum amounts of freshly harvested medusahead daily from 10:00 to 13:00h; additionally, eight experienced and seven inexperienced sheep received alfalfa hay (0.31% body weight) at the same time. All groups had a basal diet of tall fescue hay. Intake of the forages, NaCl and trace-mineralized salt blocks was measured. In Experiment 2, sheep were then clustered into nine groups of three yearlings each (n=5 early experience; n=4 experience gained during Experiment 1) and one group of two yearlings (experience gained during Experiment 1) and grazed 10 plots of medusahead-infested rangeland. Grazing events were recorded daily at 5min intervals from 08:30 to 11:00h and from 16:00 to 17:00h, and the defoliation proportion of medusahead tillers was determined every five days. During Experiment 1, medusahead intake was not affected by early experience or alfalfa availability (P>0.05) but medusahead intake across days was cyclic with more pronounced intake peaks at the beginning and end of the experiment for inexperienced animals (P<0.05). Experienced sheep showed a greater gain-to-feed ratio (P<0.05), and tended to have greater average daily body weight gains and salt intake (P<0.10) than inexperienced sheep. Sheep fed alfalfa tended to eat less trace-mineralized salt blocks than sheep that did not receive this forage (P<0.10). During Experiment 2, the proportion of grazing events recorded on medusahead by both groups (yes/no early experience) of animals was almost nil, although experienced animals tended to defoliate more medusahead tillers than inexperienced animals (P=0.10). In conclusion, when sheep were fed ad libitum amounts of medusahead, intake was low and cyclic with a more even consumption of the weed by experienced animals. Under these conditions, early experience also favored animal performance. However, it is likely that such high exposure to medusahead attenuated the subsequent use of the weed during grazing.

Performance of heifers supplemented with different levels of corn on pasture

In southern Brazil, production systems are typically extensive and rely on grazing that often results in limited forage quantity and quality, decreasing efficiency and compromising reproductive tract development. The aim of this study was to evaluate the productive performance and reproductive tract development of heifers supplemented with different levels of corn on pasture. The following supplemental treatments were evaluated: T0 [40 g trace-mineralized salt per heifer per day (80 g phosphorus/kg product)]; T1 [0.5% of body weight (BW) cracked corn + 40 g trace-mineralized salt per heifer per day]; T2 [1% of BW cracked corn + 40 g trace-mineralized salt per heifer per day], and T3 [1.5% of BW cracked corn + 40 g trace-mineralized salt per heifer per day]. Thirty-nine phenotypically homogeneous Brangus heifers (average BW = 184±17 kg, average age = 269±27 days) raised on winter pasture ( Lolium multiflorum Lam.) were randomized to 13 paddocks (one hectare each), with three heifers/paddock, to evaluate the effect of feeding different energy levels. Body condition score, average daily gain, frame score, dry matter availability, reproductive tract score, and stocking density were evaluated. The body condition score, average daily gain, reproductive tract score and stocking density increased (P<0.05) with increasing level of corn supplementation. Daily supplementation levels lower than 1.0% on Lolium multiflorum Lam. pasture can compromise the target breeding weight at 13 months of age. Therefore, daily supplementation at 1.0% of BW after weaning is a strategy to improve the economic and biological efficiency of livestock production systems, allowing to increase stocking density and to anticipate the age of heifers at first breeding.

Continuous vs. Rotational Grazing of Cool Season Pastures During the Summer Months

Continuous vs. Rotational Grazing of Cool Season Pastures During the Summer Months

Effects of increasing levels of corn distillers dried grains with solubles to steers offered moderate-quality forage1

Supplementation of forage-fed livestock has been studied for decades; however, as by-products become available research is needed to determine optimal feeding rates for increased efficiency. Five ruminally and duodenally cannulated beef steers (446 +/- 42 kg of initial BW) were used in a 5 x 5 Latin square to evaluate effects of increasing level of supplemental corn distillers dried grains with solubles (DDGS; 25.4% CP, 9.8% fat, DM basis) on DMI, rate and site of digestion, ruminal fermentation, and microbial efficiency. Diets consisted of ad libitum quantities of moderate-quality smooth brome hay (10.6% CP; DM basis), free access to water and trace mineral salt block, and 1 of 5 levels of DDGS (0, 0.3, 0.6, 0.9, and 1.2% of BW daily of DDGS; DM basis). Diets were formulated to meet or exceed the estimated rumen degradable protein requirements (assumed microbial yield = 10.5%). All supplements were fed at 0600 h before forage was fed. Steers were adapted to diets for 14 d followed by a 7-d collection period. Hay OM intake decreased (linear; P < 0.001), whereas total OM intake increased (linear; P < 0.001) with increasing DDGS level. Total CP intake, duodenal OM and CP flows, and total tract OM and NDF digestibilities increased (linear; P <or= 0.01) with increasing level of DDGS. Apparent ruminal and true ruminal CP digestibilities increased linearly (P <or= 0.007), and total-tract CP digestibility increased quadratically (P = 0.02) with increasing DDGS level. Average ruminal pH was not different (P = 0.89) among treatments. Ammonia concentration increased (quadratic; P = 0.02) with increasing DDGS. Acetate proportions (molar %) decreased linearly (P < 0.001), whereas butyrate (molar %) increased linearly (P = 0.007), and propionate (molar %) increased quadratically (P = 0.04) with increasing DDGS. Ruminal DM fill decreased quadratically (P = 0.03), whereas fluid dilution rate tended to increase cubically (P = 0.08) with increasing DDGS. In situ rate of hay and DDGS DM disappearance responded cubically (P <or= 0.03) with greatest disappearance occurring with the 0.9% treatment. In situ rate of ruminal CP degradation of hay and DDGS increased (linear; P <or= 0.003) with increasing DDGS. Feeding 0.3% up to 1.2% of BW daily of DDGS as a supplement to forage-based diets resulted in no adverse effects on forage digestion or fermentation and resulted in increased nutrient supply in steers fed moderate-quality smooth brome hay.

Effect of chlortetracycline in a trace mineral salt mix on fertility traits in beef cattle females in Florida.

The study objective was to determine the effect of chlortetracycline in an ad libitum trace-mineralized salt mix given to heifers before and(or) during bull exposure on the proportion pregnant and the time to conception in a fixed breeding period. Heifers (n = 768), 13 to 15 mo of age, were individually identified, immunized (Leptospira, Campylobacter fetus), examined (body condition score, vaginal lesion score, BW), and randomly allocated within 2 x 2 factorial blocks of treatments where trace mineral salt with and without chlortetracycline medication was provided in similar but nonadjacent pastures either before and(or) during bull exposure. The chlortetracycline feeding period was about 30 d for each. In the 2 d immediately before bull exposure, heifers were examined (body condition score, vaginal lesion score, reproductive tract evaluation) and reallocated to treatment pastures. Pregnancy was determined by per rectal palpation at 45 d following bull removal. Mineral intake was below that expected for heifer groups and, as a result, chlortetracycline intake was estimated at less than one-third of that targeted. Many heifers were not cycling reproductively at the onset of bull exposure (n = 456, 60.3%, based on a reproductive tract score < 3). Despite these limitations, heifers receiving chlortetracycline treatment before breeding had a pregnancy percentage of 65% (chlortetracycline before and during breeding 67% and chlortetracycline before breeding 61.8%) compared to those receiving no treatment before breeding (53%, P < 0.03; no chlortetracycline before or during breeding 60.4% and chlortetracycline during breeding 47.4%). Heifers receiving chlortetracycline treatment before breeding were 57% more likely to become pregnant than those not treated before breeding. Change in vaginal lesion score was associated with the proportion pregnant, but neither body condition score nor average daily gain were.

Offstream water and trace mineral salt as management strategies for improved cattle distribution.

The objective of this study was to test the combined effect of offstream water and trace mineral salt on cattle distribution in a riparian meadow and its adjacent uplands. From July 15 to August 26, 1996 and 1997, three treatments were each randomly assigned to one pasture in each of three blocks. Sixty cow/calf pairs were then randomly allotted to the grazed pastures. The treatments included 1) stream access and access to offstream water and trace-mineral salt (off-stream), 2) stream access and no access to offstream water or trace-mineral salt (no-offstream), and 3) ungrazed control. The response of cattle was measured through visual observations of cattle distribution, grazing activity and travel distance, cow/calf performance, and fecal deposit distribution. Distribution patterns of the cattle, measured as the distance of cattle from the stream, was characterized by a time of day x treatment x time in grazing period x year interaction (P < 0.05). No-offstream cattle began the day further from the stream than offstream cattle but consistently moved closer to the stream after the morning grazing period (0600 to 0900). Differences in distribution patterns between the two treatments were more pronounced early in the grazing period than late in the grazing period. Grazing activity, fecal deposit distribution, and travel distance of cattle were not affected by the presence of offstream water and trace-mineral salt. Cows and calves with offstream water and trace-mineral salt gained 11.5 kg and 0.14 kg/d more, respectively, than no-offstream cows and calves averaged across years (P < 0.05). Overall, cattle distribution patterns and cow/calf performance were influenced by the presence of offstream water and trace-mineral salt. Changes in distribution were most pronounced early in the grazing season.

Effects of dietary vitamin E supplementation during late pregnancy on lamb mortality and ewe productivity

Objective To determine the effect of feeding vitamin E to ewes during late pregnancy on lamb mortality and ewe productivity. Design Prospective study. Animals 1,302 mature Rambouillet and Targhee ewes. Procedure During a 3-year period, approximately 430 ewes/y were randomly allocated to 2 groups; supplement-group ewes were fed additional vitamin E and control-group ewes were not. Beginning approximately 3 weeks before the first expected lambing date, ewes were fed 2.3 kg (5 lb) of alfalfa-grass hay/d and 0.23 kg (0.5 lb) of barley-based pellets/d with or without supplemental vitamin E. Pellets that were supplemented contained 1,450 mg of dl-α-tocopherol acetate/kg (658 mg/lb) of feed and provided an additional 330 IU of vitamin E/ewe/d. Selenium was incorporated into a trace mineral salt and fed free choice to all ewes throughout pregnancy. Results Supplemental vitamin E had no effect on ewe weight, body condition score, fertility, or prolificacy. In ewes that lambed in the early part of the lambing season, vitamin E supplementation significantly reduced lamb mortality, compared with no supplementation (12 vs 17%, respectively). Consequently, supplement-group ewes had significantly greater total body weight of lambs per ewe at the time of weaning, compared with control-group ewes. Differences were not observed between ewe groups in lamb mortality or total body weight of lambs per ewe at the time of weaning when ewes lambed during the late part of the lambing season. Clinical Implications If ewes are fed additional vitamin E 3 weeks before parturition, those that lamb in the early part of the lambing season may have low lamb mortality and, thus, higher total body weight of lambs per ewe at the time of weaning. (J Am Vet Med Assoc 1998;212:997–1000)

Block Intake by Beef Cattle

Seventy-two Hereford, Angus, and Hereford x Angus cows were used to examine free-choice intakes of block feeds: trace-mineralized salt (TM), iodized salt (I), 21% protein (21P), and 36% protein (36P). On all trials, two lots (six cows each) were group fed, and a third group (six cows) was individually fed using Calan electronic gates. Blocks and block waste were weighed daily for 1yr. Mean daily consumption of TM and I blocks by individually and group-fed cows differed (P<.05) among and within cows by period. Wide day-to-day variability was observed within and between cows for selected 10-d periods. Several of the individually fed cows did not consume any of the salt-type blocks for periods of several weeks. There were no differences (P>.1) in between-cow intake within periods for individually fed cows. Within-cow and within- period intake differed (P<.01) for both the individually and group-fed animals. Maximum consumption occurred during periods of low quantity and quality of forage. Consumption of 36P block differed (P<.01) between cows and between periods for individually fed cows while group-fed cows were different (P<.01) only between periods. Highest average daily intake generally occurred in summer while the lowest intake for I, 21P, and 36P blocks occurred in the spring. Seasonal intakes were different (P<.01) for the individually fed cows on all trials. Coefficients of variation were much greater for the salt-type blocks than for the softer, proteintype blocks. These trials suggest highly variable intakes of block-type feed by beef cattle and offer some explanations for the variability. Some implications of the variability are discussed.

Composition of formaldehyde- and formic acid-treated alfalfa and orchardgrass silages harvested at two maturities and their effects on intake and growth by Holstein heifers.

Alfalfa and orchardgrass herbages were each harvested at two maturities (May 22 to 25 vs June 5 to 7) in primary growth and directly ensiled with 5 kg of a mixture of 30% formic acid and 25% formaldehyde per metric ton of fresh herbage in upright conventional silos. Alfalfa silage contained less NDF (71%) and more N (150%) and hot-water-insoluble N (117%) than orchardgrass silage did. Major differences between silages were that orchardgrass contained 20.4 percentage units more NDF and 1.10 percentage units less N than alfalfa. The NDF increased 104% and total N decreased to 86% with advancing maturity. Twenty-eight yearling Holstein heifers (223 kg BW) were given ad libitum access to the four silages with trace mineral salt, and growth rate was measured in a 119-d period. Daily DE intake was 297 kcal/kg.75 BW for heifers fed alfalfa silage compared with 202 kcal/kg.75 BW for heifers fed orchardgrass silage. Daily gain was 992 g for heifers fed alfalfa compared with 661 g for heifers fed orchardgrass. Gross efficiency, or gain per unit of DE, was similar for heifers fed orchardgrass and alfalfa. Rate of gain was primarily a function of ad libitum intake of DE. Heifers fed alfalfa had greater plasma essential amino acid concentrations (122%) than those fed orchardgrass did. Late alfalfa produced greater ADG than orchardgrass harvested 2 wk earlier.

Performance and Internal Parasite Burden of Stocker Steers Treated Continuously with Morantel Tartrate

Three experiments were conducted to evaluate performance and fecal nematode egg counts in grazing stocker cattle receiving morantel tartrate (MT) in two continuously administered forms. In Exp. 1, 80 crossbred steers either received no anthelmintic (C) or were dewormed at the initiation of a 140-d bermudagrass grazing study with either levamisole injection (L) or MT in a sustained-release trilaminate (MSRT). Anthelmintics did not affect performance parameters, but fecal nematode egg counts were lowest from L, intermediate from MSRT, and highest from C at the end of the study. In Exp. 2, 60 crossbred steers grazing fall-regrowth smooth bromegrass were offered a mineral mixture of trace-mineralized salt and dicalcium phosphate (3:1 ratio) with 0 or 10% dried molasses and 0 or 5.58 mg/g MT. Steer gains were similar (P>.10) across treatments, but fecal egg counts were reduced (P<.05) by MT. In Exp. 3, 120 crossbred steers grazing smooth bromegrass pastures were used in an experiment with a 2 x 2 factorial arrangement of treatments to evaluate the effects of grazing intensity and 5.58 mg/g MT in a mineral mixture. Steers grazing at the highest stocking rate (3.7 steers/ha) had reduced (P<.01) gains but improved (P<.01) gain/ha compared with those grazing at the lower rate (2.5 steers/ha). Morantel tartrate reduced (P<.01) fecal nematode egg counts but had no effect on animal performance at either stocking rate. Morantel tartrate was effective in reducing fecal egg counts, but parasite burden in control animals in all three experiments was not sufficient to reduce animal performance.

Influence of Pelleting on the Comparative Feeding Value of Cottonseed Meal in Receiving Diets for Feedlot Calves

Three trials were conducted to evaluate the influence of pelleting solvent-extracted cottonseed meal on its comparative feeding value in receiving diets for feedlot calves. Treatments consisted of a basal diet supplemented with cottonseed meal in either a loose or pelleted (6.4-mm diameter) form. The basal diet contained (dry matter basis) 5.1% alfalfa hay, 17.3% sudangrass hay, 46.4% steam-flaked corn, 19.0% cottonseed meal, 5.8% cane molasses, 3.2% fat, 1.1% dicalcium phosphate, 1.3% limestone, .41% urea, .50% trace mineral salt and 2,200 IU/kg vitamin A. In two 56-d receiving trials involving 240 crossbred calves (100 kg), physical form of supplemental cottonseed meal did not influence feed intake or calf performance (P > .20). In a metabolism trial involving four crossbred calves (128 kg) with cannulas in the rumen and proximal duodenum, substituting pelleted cottonseed meal for the ground form did not influence ruminal or total tract digestibility of organic matter, acid detergent fiber or N (P > .20). Feeding value of cottonseed meal in receiving diets for feedlot calves was not improved through pelleting.

MINERAL ELEMENTS IN CEREAL GRAINS AND LEGUMES GROWN IN PRINCE EDWARD ISLAND

Samples of barley, wheat, clover and alfalfa grown in Prince Edward Island were analyzed for Ca, P, K, Mg, Mo, S, Mn, Zn and Fe. Compared with the requirements for livestock, the cereal grains and forages tended to be low or deficient in several minerals. The need for a suitable trace-mineralized salt in cattle and sheep diets is indicated. Key words: Minerals, trace elements, grains, legumes

Interaction Between Nickel and Protein Source in the Ruminant

Eighty growing steers were used to determine the effect of nickel supplementation on performance and metabolic parameters of steers fed corn silage-based diets supplemented with different crude protein sources. Crude protein sources examined included: (1) soybean meal, (2) blood meal, (3) urea, and (4) blood meal-urea (two-thirds of supplemental nitrogen from blood meal and one-third from urea). The protein sources differed in ruminal degradability, nitrogen solubility, and nickel content. Nickel was added within each protein treatment to supply either 0 or 5 ppm of supplemental nickel. The experiment was 84 d in duration and rumen fluid and blood samples were collected on days 42 and 80. Average daily gain and feed efficiency were not affected by nickel supplementation. The addition of 5 ppm supplemental nickel greatly increased rumen bacterial urease activity regardless of protein source. When samples were collected prior to feeding on day 80, nickel increased serum urea nitrogen concentrations in steers fed urea, but decreased circulating urea concentrations in animals fed blood meal or the blood meal-urea combination.Ad libitum intake of trace mineral salt was greatly reduced in steers receiving 5 ppm supplemental nickel. The present study suggests that the source of protein may influence ruminant responses to dietary nickel.

Selenium and sulfur supplementation to steers grazing tall fescue

Forty steer calves averaging 257 kg were allotted to a randomized complete block design experiment containing 10 animals per treatment. Four tall fescue pastures of 5.7 ha each were utilized during the 84-d grazing study. Each pasture treatment block contained 10 calves. Calves were fed a control supplement of 96.9% ground corn and 3.1% trace mineral salt in two pastures, or a sulfur supplement that contained 94.3% ground corn, 3.1% trace mineral salt, and 2.5% elemental sulfur in the remaining two pastures. Each supplement was fed at the rate of 0.45 kg/head daily. One-half of the calves in each pasture were injected with 15 mg selenium (Se) as sodium selenite initially and at 28-d intervals throughout the trial. The treatments were as follows: (1) control-no sulfur, no selenium; (2) selenium, no sulfur; (3) sulfur, no selenium and; (4) selenium plus sulfur. Calf weights were monitored and certain blood parameters measured every 28 d. Average plasma Se values were increased (P < 0.001) from 0.021 ppm in calves not receiving Se to 0.043 ppm in those receiving Se. Plasma urea nitrogen levels were not affected by Se administration, but were lowered (P <0.05) from 16.6 to 15.8 mg/100 mL by sulfur administration. All plasma amino acids measured, except methionine, phenylalanine, argi-nine, and citrulline, were cleared from the blood in response to Se supplementation as reflected by their lower concentrations when compared with other treatment groups. Overall average daily gains were not significantly (P > 0.10) increased by sulfur supplementation, but were increased (P < 0.05) from 0.33 kg/d in calves not receiving Se to 0.43 kg/d in those receiving Se injections. Significant interactions between fulfur and Se were not noted.