Effects of dried whey and copper sulfate on the growth responses to organic acid in diets for weanling pigs

Five 21-d to 28-d experiments involving 484 pigs weaned at 28 +/- 2 d of age were conducted to evaluate the effects of addition of organic acid to a fortified, corn-soybean meal diet (CS) or to a similar diet containing 15% dried whey (CSW) on performance of pigs. The effects of an antibiotic-sulfonamide combination (110 mg chlortetracycline, 110 mg sulfamethazine, 55 mg penicillin/kg) and the interactive effects of Cu sulfate (250 ppm Cu) and acid also were evaluated. The acid was a commercial product consisting of 96% organic acid (citric acid and Na citrate, 2:1). Treatments in Exp. 1 and 2 were factorial arrangements of the CS or CSW basal diets supplemented with 0 or 1% (Exp. 1) and 0, .5 or 1% (Exp. 2) of the acid product. Pigs fed diets containing whey consumed more feed (P less than .01) and gained weight faster (P less than .05), but they had feed/gain responses similar to those of pigs fed the CS diet. Addition of 1% acid improved (P less than .01) growth rate of pigs fed the CS diet but did not improve (P greater than .25) growth rate of pigs fed the CSW diet. Feed/gain was improved (P less than .01) by acid addition to both the CS and the CSW diets. Improvements in gain and feed/gain were similar for the two levels of acid. In Exp. 3 and 4, factorial combinations of 0 and 1% acid and 0 and 250 ppm Cu were evaluated in diets containing an antibiotic-sulfonamide combination. In addition, a negative control diet (no antibiotics, acid or Cu) was included. Pigs fed diets containing antibiotics gained faster and more efficiently (P less than .01) than those fed the control diet.(ABSTRACT TRUNCATED AT 250 WORDS)     

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

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

Effect of vitamin E and copper on the vitamin E status and performance of growing pigs

A 13-wk trial was conducted with 32 pigs to determine the effects of dietary Cu (250 ppm) and alpha-tocopheryl acetate (ATA, 22 IU/kg) on the performance, serum enzymes, serum and tissue tocopherols, and antibody production in growing pigs. Pigs were fed corn-soybean meal diets containing 21% CP the first 4 wk and 18% CP during the rest of the trial. All feed was stored a minimum of 14 d before it was fed. The addition of Cu decreased (P less than .01) the concentration of alpha-tocopherol in the feed. alpha-Tocopherol concentrations were less than .01 mg/kg in the starter diet and less than 2 mg/kg in the grower diet after 14 d of storage. Supplemental Cu or ATA had no effect on ADG, feed intake, or gain:feed during the first 4 wk. During wk 5 to 13, the addition of Cu to diets containing no ATA increased daily feed intake and decreased gain:feed, but with ATA addition, feed intake decreased and gain:feed increased, resulting in a Cu x ATA interaction (P less than .05). The addition of Cu or ATA had no effect (P greater than .1) on serum glutathione peroxidase or lactic dehydrogenase activity. Serum tocopherols were reduced (P less than .05) by the addition of Cu during wk 1 to 4, 6 (P less than .01), and 7 (P less than .05) and increased (P less than .01) by ATA addition during the entire experiment. The addition of ATA increased the tocopherol concentrations in bile, ham, heart, pancreas, kidney, spleen, liver, psoas and longissimus muscle (P less than .01), kidney fat, backfat, and adrenal gland (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of chelated copper sources on performance of nursery and growing pigs

Four experiments were conducted to determine the effect of Cu source and level and an antimicrobial agent on performance of nursery (6 to 25 kg) and growing (20 to 65 kg) pigs. Copper was fed either as CuSO4.5H2O (CS), inorganic chelated Cu (ICC) or organic chelated Cu (OCC) to provide 31.25 to 250 ppm supplemental Cu. In Exp. 1, 224 pigs were used to study Cu source and level added to nursery diets. No difference (P less than .05) among treatments was observed during the nursery period. Treatments were continued the first 56 d of the growing-finishing period. Regardless of the Cu source, pigs receiving 125 ppm added Cu gained faster (P less than .05) than pigs in other treatments. In Exp. 2, 216 pigs were used to determine the optimum level of CS and ICC in nursery diets. Pigs were less efficient (P less than .01) when Cu was added at 62.5 and 125 ppm than at 250 ppm (1.69, 1.72 and 1.59, feed/gain respectively). In Exp. 3, no differences (P greater than .05) in performance between sources or among levels of Cu were found. In Exp. 4, 216 pigs were utilized to determine the combined effects of Cu source and an antimicrobial on performance. Pigs fed ICC were less efficient (P less than .01) than pigs fed either OCC or CS (1.99, 1.85 and 1.90, respectively). The inorganic and organic chelated Cu compounds used in these studies were not more efficacious than CS for nursery or growing pigs.     

Effects of source and level of copper on performance and liver copper stores in weanling pigs

Five 28- to 33-d experiments involving 460 crossbred pigs weaned at 28 +/- 2 d of age (initial weight, 6.7 to 8.1 kg) were conducted to determine the effects of feeding high dietary levels of Cu sulfate (CuSO4) or Cu oxide (CuO) on rate and efficiency of gain and liver Cu stores of weanling pigs. The pigs were housed in groups of five to six/pen and fed a fortified, unmedicated, corn-soybean meal-dried whey basal diet (1.1% lysine, 30 ppm Cu). In Exp. 1 and 2, pigs (eight replicates) were fed the basal or the basal plus 125 or 250 ppm Cu from CuSO4 or CuO for 28 d. In Exp. 3 and 4, four replications were fed the same diets as in Exp. 1 and 2 plus two additional diets (500 ppm Cu from CuSO4 or CuO). In Exp. 5, dietary levels of 0, 125, 250, 375 or 500 ppm Cu from CuSO4 were evaluated using four replications. At the end of each experiment, the liver from one pig in each pen was collected for Cu analysis. Overall, rate and efficiency of gain were improved (P less than .01) by feeding 125 or 250 ppm Cu as CuSO4, with the 125 ppm dietary level being about 75% as effective in stimulating growth as 250 ppm. Performance of pigs was not different from controls when the highest (500 ppm) level of Cu (from CuSO4) was fed. Liver Cu increased 10- to 70-fold when 250 to 550 ppm Cu from CuSO4 was included in the feed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of dietary protein concentrations on performance and nitrogen repletion in stressed calves

Three trials were conducted to determine the influence of dietary CP concentration on health and performance of market-transport-stressed feeder calves (Exp. 1 and 2) and on repletion of nutrients lost during a 3-d feed and water deprivation period in steers fed at maintenance energy intake (Exp. 3). In Exp. 1 (84 calves) and 2 (256 calves), feeder calves averaging 184 kg were transported from Tennessee to Texas. In Exp. 1, calves were fed receiving diets containing either 12 or 16% CP. In Exp. 2, calves were fed diets containing 12 or 16% CP and .8 or 1.3% potassium in a 2 x 2 factorial arrangement of treatments. In Exp. 3, four Hereford steers averaging 253 kg were used in an N balance trial. Steers were deprived of feed and water for 3 d and then were limit-fed (1 x maintenance energy requirements) diets calculated to meet 100, 120, 140 or 160% of CP maintenance requirements for 14 d in a 4 x 4 Latin square design. In Exp. 1, calves fed the 16% CP diet had faster (P less than .05) daily gains and higher (P less than .10) feed consumption than calves fed the 12% CP diet during the first 14 d. In Exp. 2, calf performance was not affected by diet CP or K content. Calves fed the 16CP-1.3K diet had lower (P less than .10) mortality than calves on the remaining treatments. In Exp. 3, N balance and serum urea N increased linearly (P less than .05) with increasing dietary CP. Results of these studies are interpreted to indicate that the CP requirement (g/d) of market-transport-stressed feeder calves is similar to requirements of nonstressed calves; however, the CP concentration of the diet of stressed calves may need to be increased when feed intakes are low.     

Zinc-amino acid complexes for swine

Two experiments were conducted to determine the effect of sources of dietary zinc on gain, feed conversion and blood and bone traits of swine. In the first experiment 96 pigs were used in a 28-d study. The pigs were fed diets with no supplemental Zn or with either 9 or 12 ppm supplemental Zn from zinc sulfate (ZnSO4), zinc methionine (ZnMet) or zinc methionine with picolinic acid (ZnMet w/PA), each with or without 5% added corn oil. There were differences (P less than .05) in average daily gain (ADG) and average daily feed intake (ADFI) between the pigs fed the two organic Zn sources, with those fed ZnMet w/PA showing the better gains and feed conversion. However, neither organic Zn source resulted in pig performance that was different from either the diet with no supplemental Zn or the diets supplemented with Zn from ZnSO4. In the second experiment the same dietary Zn sources and treatments were fed as in Exp. 1 except that corn oil was deleted as a variable. No differences in ADG, ADFI, feed/gain (F/G) or in changes in serum Zn or Cu were observed among treatments during either the 21-d nursery or the 56-d growing periods. During the subsequent 56-d finishing period ADG and ADFI were greater (P less than .01) for pigs fed the Zn-supplemented diets than for those fed the diets without supplemental Zn. There were no differences among treatments in F/G during the finishing period. Zn content of bone ash was lower (P less than .01) in the non-Zn-supplemented pigs. These data suggest that the Zn sources used are of similar biological value and do not support the theory that picolinic acid aids Zn absorption.     

Effects of dietary energy level and supplemental protein source on performance of growing steers and nutrient digestibility and nitrogen balance in lambs

Four experiments were conducted to evaluate three crude protein (CP) sources (urea, U; soybean meal, SBM; corn gluten meal, CGM) in diets based on corn silage (high energy) or grass hay (low energy). In Exp. 1 and 2, growing steers were fed all combinations of energy and protein source at 10.5 or 12% CP. Steers fed high energy diets or 12% CP had improved (P less than .05) daily gains and feed:gain over 84 d. Protein source had no effect (P greater than .05) on performance except that steers fed U consumed more (P less than .05) feed than those fed CGM. Steers were fed experimental diets to a common weight and switched to an 85% concentrate diet for finishing. During finishing, steers fed low energy diets in the growing period consumed more (P less than .05) feed and had increased (P less than .05) feed:gain compared with those fed high energy diets. Growing lambs were fed the same diets as steers. At 10.5% CP, lambs fed high energy diets had higher (P less than .05) digestibilities of dry matter (DM), organic matter (OM), nitrogen (N) and fiber components, and retained more (P less than .05) N. For lambs on 12% CP, high energy diets had higher (P less than .05) DM and OM digestibilities and lower (P less than .05) N digestibilities. At 12% CP, energy level had no effect (P greater than .05) on N retained. Protein source had no effect (P greater than .05) on N retention. There appeared to be no advantage in supplementing with ruminally undegradable proteins, i.e. CGM, in these experiments.     

Influence of level of dietary protein or energy on effects of ractopamine in finishing swine.

The effect of ractopamine, a beta-adrenergic agonist, on growth, nutrient utilization, and carcass composition was studied in pigs fed either 18% CP, 12% CP, or 18% CP restricted (RES = 67% of ad libitum) diets. The 18 and 12% CP diets provided 3.52 and 3.68 Mcal of DE/kg, respectively. All pigs were fed a low-protein (12% CP) diet during pretreatment growth from 15 to 60 kg. Ractopamine at 20 or 30 ppm (30 ppm for RES pigs) in the diet was fed from 60 kg live BW until slaughter at 105 kg (9 pigs/treatment). No ractopamine treatment effect (P greater than .05) was observed for either daily gain or gain/feed, although gain/feed was improved by 8% in both of the ad libitum groups. Ractopamine treatment resulted (P less than .01) in an overall reduction of carcass lipid by 8%, an increase of carcass protein by 5%, and a 21% improvement in the efficiency of protein utilization; the greatest changes occurred in the pigs fed the 12% CP diet (-17%, +11%, and +32%, respectively). The ad libitum daily feed intake was 15% less for pigs fed the 12% CP diet than for those fed the 18% CP diet (P less than .01), and there was a 10% reduction in intake of both diets with the addition of ractopamine (P less than .05). Both carcass lipid and protein deposition seemed to be closely related to energy intake (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of copper addition to diets with various iron levels on the performance and hematology of weanling swine

A 2 x 6 factorial experiment with Cu added at 5 or 250 ppm and Fe added at 50, 100, 150, 200, 250, or 300 ppm was conducted using 480 crossbred weanling pigs with an average initial weight of 7.0 kg. The basal corn-soybean meal-whey diet contained 4 ppm Cu, 169 ppm Fe, and 199 ppm Zn. Pigs were allotted by weight, sex, and litter outcome group and had ad libitum access to feed and water during the 28-d trials. Animals were weighed and pen feed intake was recorded weekly. Blood samples were collected on d 1, 14, and 28 of the experiment. The addition of 250 ppm Cu increased ADG (P less than .001) and average daily feed intake (ADFI, P less than .01) during the 28-d trials. The addition of Fe had no effect on ADG and ADFI (P greater than .10). A Cu x Fe interaction (P less than .01) was observed for feed/gain. Increasing Fe levels linearly improved hematocrit status (P less than .05) on d 28 of the trial. A Cu x Fe interaction (P less than .08) was observed for hemoglobin at the end of the trial; hemoglobin levels were increased by the addition of Fe to the diet containing 250 ppm of Cu. Plasma Cu was increased (P less than .001) by the addition of 250 ppm of Cu. Plasma Fe was low when either 50 or 100 ppm of Fe was added in the presence of 250 ppm of Cu, but it was not affected at other levels, resulting in a Cu x Fe interaction (P less than .05). These data indicate that levels of added Fe up to 300 ppm may help to improve the hematological status of weanling pigs fed growth-promoting levels of Cu but that it has little effect on performance.     

Effect of receiving diets containing alfalfa and certain feed additives on performance of feeder pigs transported long distances

Three experiments were conducted to determine the effect of receiving diets containing alfalfa meal and certain feed additives on performance of comingled feeder pigs transported 900 to 1,100 km. In Exp. 1, the inclusion of 9.4% dehydrated alfalfa meal in receiving diets for 2 wk resulted in no difference (P greater than .1) in gain or feed conversion from purchase to market compared with pigs fed a basal corn-soybean meal (CS) diet or a diet containing 20% ground whole oats (O). In Exp. 2, pigs fed receiving diets containing 10% dehydrated alfalfa meal had no improvement (P greater than .1) in gain (.60 vs .61 kg/d) or conversion (3.25 vs 3.17) compared with CS-fed pigs. In Exp. 3, pigs fed a receiving diet for 2 wk containing 10% mid-bloom alfalfa ate more (P less than .002) feed daily for 2 wk (.82 vs .76 kg) and overall (P less than .04; 1.92 vs 1.85 kg) and had an improved (P less than .03) daily gain from purchase to market (.61 vs .59 kg) compared with CS-fed pigs. In Exp. 2, pigs fed diets containing 44 mg/kg tylosin (T) gained similar to pigs fed no additive (O) and slower (P less than .01) than pigs fed 110 mg/kg chlortetracycline (CTC; .59, .60 and .63 kg/d), with no significant differences in feed to gain conversion (3.12, 3.23 and 3.18).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of high dietary manganese as manganese oxide or manganese carbonate in sheep

Twenty-four crossbred Florida native wether lambs, 28 kg initially, were assigned randomly to a basal diet (31 ppm Mn dry matter basis) supplemented with either 0, 500, 1,000, 2,000 or 4,000 ppm Mn from feed grade MnO or 2,000, 4,000 or 8,000 ppm Mn from reagent grade MnCO3. There were three sheep/treatment, with ad libitum access to feed and tap water. After 84 d, all animals were slaughtered and tissues removed for analysis. Dietary Mn at the highest levels from either source reduced (P less than .05) average daily feed intake and average daily gain. Hemoglobin and hematocrit were not affected by dietary Mn. Manganese concentration in kidney, spleen, heart, skeletal muscle, bone, serum (P less than .01) and liver (P less than .05) increased as dietary Mn increased. Kidney P was reduced (P less than .05) as dietary Mn increased; however, no other tissue minerals were affected. At comparable levels of supplementation, sheep fed feed-grade MnO exhibited numerically greater tissue Mn concentration than did those fed reagent-grade MnCO3 and regression analysis indicated higher rates of tissue uptake in MnO-supplemented sheep. Reduced feed intake and gain and apparent Mn homeostatic failure in liver were the only observed effects that may have been related to Mn toxicosis.     

Zinc methionine for ruminants: relative bioavailability of zinc in lambs and effects of growth and performance of growing heifers

Studies were conducted to evaluate zinc methionine (ZnMet) as a source of Zn for ruminants. Experiment 1 compared the availability of Zn in ZnMet and zinc oxide (ZnO) in lambs fed a semi-purified diet deficient in Zn. Based on growth rate and animal performance, plasma Zn and plasma alkaline phosphatase activity, no differences in Zn availability were detected between the two Zn sources. Apparent absorption of Zn also was similar, but Zn retention was higher (P less than .01) in lambs fed ZnMet because of a tendency for lower urinary Zn excretion (P less than .19) in this group. Zinc absorption and retention by lambs were similar for the two Zn sources in Exp. 2 when 20 mg Zn/kg was added to an orchardgrass hay-based diet containing 30 mg Zn/kg. In Exp. 3, lambs were dosed orally with 300 mg of Zn as ZnO or ZnMet, and the increase in plasma Zn following dosing was monitored. The increase in plasma Zn above predosing values was similar at 6 h but was higher at 12 (P less than .10) and 24 h (P less than .05) postdosing in lambs given ZnMet. Thirty-six Hereford x Simmental heifers (271 kg) were used in Exp. 4 to determine the influence of supplementing Zn (25 mg/kg) as ZnO or ZnMet of growth performance and Zn status. Heifers were fed a corn silage-based diet that contained 23.1 mg Zn/kg during the 126-d study. Zinc supplementation to the basal diet increased (P less than .05) gain and feed/gain during the first 56 d, but not for the entire 126-d study.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of dietary crude protein level on rate, efficiency and composition of gain of growing beef bulls

Two experiments were conducted to evaluate the effects of dietary CP level on rate, efficiency and composition of gain of growing beef bulls. In Exp. 1, 59 bulls (333 +/- 15.8 kg) were used. Eleven bulls were slaughtered on d 0 to provide an estimate of initial carcass composition (9-10-11 rib section chemical analyses), and remaining bulls were assigned to treatment diets containing 10, 12 or 14% dietary CP. Bulls fed the 10% CP diet grew slower (P less than .05) than bulls fed the 12 or 14% CP diets, although dry matter intake and feed-to-gain ratio did not differ. Bulls fed the 12% CP diet had fatter carcasses (P less than .05) than bulls fed the 10 or 14% CP diets and had greater daily fat accretion than bulls fed the 10% CP diet. In Exp. 2, 60 bulls (318 +/- 9.0 kg) were used. Bulls were assigned to initial slaughter (n = 6) or to one of three dietary treatments, 10, 12 or 14% CP, and were slaughtered after feeding for 66, 136 or 202 d (n = 6 . treatment -1 . slaughter time -1). Bulls fed 10% CP diets had lower (P less than .05) rates of carcass protein accretion during d 0 to 136 and d 0 to 202. Carcass fat gain was similar among treatments over the entire experiment, although bulls fed the 14% CP diet gained more fat during d 0 to 136 than bulls fed the other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)     

Response of starter pigs to supplementation of corn-soybean meal diets with organic acids

Four growth experiments were conducted to assess the effects of organic acid supplementation on performance of starter and finisher pigs. Three 4-wk starter experiments utilized 392 pigs fed simple corn-soybean meal diets. A fourth experiment employed 135 finisher pigs in a 6-wk study. Each of the starter experiments was initiated immediately after weaning; piglets were 30 +/- 3 d of age. In Exp. 1, weanling pigs fed a 19% crude protein, simple corn-soybean meal diet were compared with pigs fed similar diets supplemented with 2% propionic, fumaric, or citric acid. Addition of each acid improved (P less than .07) efficiency of gain, while propionate depressed (P less than .05) feed intake. Additions of 1, 2, 3 or 4% fumarate were made in Exp. 2, resulting in linear daily gain and feed efficiency improvements (P less than .05). In Exp. 3, a possible protein-sparing effect of fumaric acid was investigated. Increasing protein levels from 16 to 20% improved daily gain (P less than .01) and feed efficiency (P less than .0001); fumarate supplementation (2%) increased (P less than .01) gain:feed. However, there was no protein X fumaric acid interaction. In Exp. 4, no treatment effects were noted with performance of finisher pigs fed a 14% crude protein, corn-soybean meal diet was compared with that of pigs fed similar diets supplemented with 1.5 or 3% fumaric acid.     

Effects of increasing dietary L-carnitine on growth performance of weanling pigs

Four experiments were conducted to evaluate the effects of supplementing graded levels (0 to 100 ppm) of L-carnitine to the diet of weanling pigs on growth performance during a 34- to 38-d experimental period. A fifth experiment was conducted to determine the effects of addition of L-carnitine to diets with or without added soybean oil (SBO) on growth performance. In Exp. 1, 128 pigs (initial BW = 5.5 kg) were allotted to four dietary treatments (six pens per treatment of four to six pigs per pen). Dietary treatments were a control diet containing no added L-carnitine and the control diet with 25, 50, or 100 ppm of added L-carnitine. In Exp. 2, 3, and 4, pigs (4.8 to 5.6 kg of BW) were allotted to five dietary treatments consisting of either a control diet containing no added L-carnitine or the control diet with 25, 50, 75, or 100 ppm of added L-carnitine. All diets in Exp. 1 to 4 contained added soybean oil (4 to 6%). There were seven pens per treatment (four to five pigs per pen) in Exp. 2, whereas Exp. 3 and 4 had five and six pens/treatment (eight pigs per pen), respectively. In general, dietary carnitine additions had only minor effects on growth performance during Phases 1 and 3; however, dietary L-carnitine increased (linear [Exp. 1], quadratic [Exp. 2 to 4], P < 0.03) ADG and gain:feed (G:F) during Phase 2. The improvements in growth performance during Phase 2 were of great enough magnitude that carnitine addition tended to increase ADG (linear, P < 0.10) and improve G:F (quadratic, P < 0.02) for the entire 38-d period. In Exp. 5, 216 weanling pigs (5.8 kg of BW) were allotted (12 pens/treatment of four to five pigs per pen) to four dietary treatments. The four dietary treatments were arranged in a 2 x 2 factorial with main effects of added SBO (0 or 5%) and added L-carnitine (0 or 50 ppm). Pigs fed SBO tended (P < 0.07) to grow more slowly and consumed less feed compared with those not fed SBO, but G:F was improved (P < 0.02). The addition of L-carnitine did not affect (P > 0.10) ADG or ADFI; however, it improved (P < 0.03) G:F. Also, the increase in G:F associated with L-carnitine tended to be more pronounced for pigs fed SBO than those not fed SBO (carnitine x SBO, P < 0.10). These results suggest that the addition of 50 to 100 ppm of added L-carnitine to the diet improved growth performance of weanling pigs. In addition, supplemental L-carnitine tended to be more effective when SBO was provided in the diet.     

Effects of supplemental protein source and level of urea on intestinal amino acid supply and feedlot performance of lambs fed diets based on alkaline hydrogen peroxide-treated wheat straw.

Two experiments were conducted to determine the effects of supplemental CP source and level of urea on intestinal amino acid (AA) supply and feedlot performance of lambs fed diets based on alkaline hydrogen peroxide-treated wheat straw (AHPWS). In Exp. 1, five cannulated (ruminal, duodenal, and ileal) crossbred wethers (61 kg) were used in a 5 x 5 Latin square design. Treatments consisted of different sources of CP and included soybean meal (SBM), a combination of urea, distillers dried grains (DDG), and fish meal, each provided an equal portion of supplemental CP (UDF), and three levels of urea (17, 33, and 50% of supplemental CP) fed in combination with DDG (U17, U33, and U50). Organic matter and N digestibilities decreased (P less than .05) when lambs were fed U17 compared with those fed SBM. There were no differences (P greater than .05) in bacterial N or AA flows to the duodenum due to CP source despite large differences in ruminal NH3 N concentrations and lower ruminal OM digestion when lambs were fed U17. Duodenal nonbacterial N and AA flows were highest (P less than .05) in lambs fed U17 and UDF and lowest when lambs were fed U50 and SBM. Lysine concentration in duodenal digesta decreased with incremental increases in DDG. In Exp. 2, 30 individually penned ram lambs (33 kg) were allotted to five CP treatments in a randomized complete block design. Treatments were similar to those of Exp. 1, with the exception that U17 was replaced by a 14% CP diet with SBM as the supplemental CP source; all other diets were formulated to contain 12% CP. Lambs fed U50 had decreased (P less than .08) ADG and gain/feed compared with all other treatments, and lambs fed UDF had greater (P less than .05) ADG and gain/feed than lambs fed U33. It was concluded that 17% of the supplemental CP from urea seems adequate to maximize bacterial protein synthesis and that no more than 33% of the supplemental CP should be provided by urea in diets based on AHPWS. Feeding a combination of ruminally resistant protein sources with complementary AA profiles of lysine and methionine (UDF) may enhance quality of protein entering the duodenum and feedlot performance.     

Effects of corn vs corn gluten feed on site, extent and ruminal rate of forage digestion and on rate and efficiency of gain

Three digestion experiments and one growth experiment were conducted to determine site, extent and ruminal rate of forage digestion and rate and efficiency of gain by cattle offered alfalfa haylage supplemented with corn or dry corn gluten feed (CGF). In Exp. 1, eight steers were fed alfalfa haylage-based diets with substitution of corn for 0, 20, 40 or 60% of haylage in a 4 X 4 latin square. Increasing dietary corn substitution increased (P less than .05) OM, NDF and ADF digestion by steers but decreased (P less than .05) rate of in situ alfalfa DM digestion. In Exp. 2, five heifers were fed alfalfa haylage-based diets with increasing dietary levels of CGF in a 5 X 5 latin square. Increasing dietary CGF increased (P less than .05) OM, NDF and ADF digestion by heifers. In Exp. 3 and 4, cattle were fed alfalfa haylage-based diets containing either 20 or 60% corn or CGF. In Exp. 3, supplementation increased (P less than .05) OM and NDF digestion but level X supplement source interaction (P less than .05) occurred, with added CGF increasing OM and NDF digestion more than added corn. In Exp. 4, supplementation improved (P less than .05) DM intake, daily gain and feed efficiency. Dry matter intake and daily gain were greater (P less than .05) for 60% supplementation than for 20% supplementation. Overall, whereas increasing the level of dietary supplement increased (P less than .05) OM, NDF and ADF digestion, only corn addition decreased (P less than .05) rate of in situ alfalfa DM digestion. Daily gains and feed efficiencies were similar in cattle fed either corn or CGF with alfalfa haylage.     

Utilization of alkaline hydrogen peroxide-treated wheat straw in cattle growing and finishing diets.

Two experiments were conducted to evaluate alkaline hydrogen peroxide-treated wheat straw (AHPWS) in cattle growing (Exp. 1) and finishing (Exp. 2) diets. In Exp. 1, 162 crossbred steers (257 kg) were fed 66% roughage diets in an 84-d growth trial to compare AHPWS to corn silage (CS) and to evaluate different supplemental CP sources and levels. A completely randomized design with a 3 x 3 factorial arrangement of treatments was used. Factors were roughage source (CS, a 1:1 mixture of CS:AHPWS [MIX] and AHPWS) and CP treatment (13 and 11% CP with supplemental CP provided by soybean meal [13-SBM] and [11-SBM] and 11% CP with a combination of urea, corn gluten meal, and fish meal [UGF]). Lasalocid was fed at the rate of 200 mg per steer daily. Steers fed AHPWS had decreased (P less than .01) DMI compared with steers fed MIX and CS. This may be due to increased dietary Na from residual Na in AHPWS. With each incremental increase in AHPWS, ADG and gain/feed decreased (P less than .01). Dry matter intakes (kg/d), ADG (kg), and gain/feed for CS, MIX, and AHPWS were 8.0, 1.56, and .19; 8.2, 1.33, and .16; and 7.5, 1.08, and .14, respectively. Decreased performance by steers fed AHPWS may be due, in part, to a negative interaction between the lasalocid and dietary minerals. There were no differences in performance due to CP supplementation. In Exp. 2, AHPWS was compared to alfalfa hay (AH) and CS at 10 and 20% of dietary DM (2 x 3 factorial) in a 127-d finishing trial with 108 crossbred steers (341 kg).(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of dietary protein, fat or amino acids on the response of weanling swine to aflatoxin B1

Two experiments were conducted using corn from clean or aflatoxin B1 (AFB1)-contaminated (182 ppb) sources. Weanling pigs (28 d) were fed one of eight dietary treatments arranged in a 2 x 2 x 2 factorial design. In Exp. 1 (192 pigs), treatments varied in corn source (clean or AFB1-contaminated), CP level (18 or 20%) and added fat (0 or 5%). At the end of the 28-d growth trials, plasma samples were obtained. An AFB1 x CP level interaction was detected (P less than .05) for growth rate (ADG), feed intake (FI) and feed/gain ratio (F/G). Feeding AFB1 reduced (P less than .05) ADG (.30 vs .37 kg/d) and FI (.57 vs .66 kg/d) and increased F/G (1.88 vs 1.78) of pigs fed 18% CP diets. Performance of pigs fed 20% CP diets was not altered by AFB1. Adding 5% fat to diets improved (P less than .05) F/G but did not improve ADG of pigs fed AFB1. There was an AFB1 x CP x fat interaction (P less than .05) for plasma cholesterol. Adding fat or increasing the CP level prevented the depression of plasma cholesterol in pigs fed AFB1. In Exp. 2 (96 pigs), all diets contained 18% CP and the treatments varied in corn source (clean or AFB1-contaminated), added L-lysine HCl (0 or .25%) and added DL-methionine (0 or .15%). Feeding AFB1 reduced (P less than .05) ADG of pigs fed the 18% CP diet (.44 vs .50 kg/d) but not of pigs fed diets supplemented with .25% lysine.(ABSTRACT TRUNCATED AT 250 WORDS)