Changes in concentrations of trace minerals in lambs fed sericea lespedeza leaf meal pellets with or without dietary sodium molybdate.

Prolonged feeding of sericea lespedeza (SL) previously led to reduced serum concentrations of Mo, a cofactor in an enzyme complex that may be involved in weight gain. The current objective was to determine the effect of Mo supplementation on changes in serum, fecal, urine, and liver concentrations of trace minerals in lambs fed SL leaf meal pellets. Thirty ram lambs weaned in May (84 ± 1.5 d of age and 27 ± 1.1 kg; D 0) were blocked by BW, breed type (full or three-fourths Katahdin), and EBV of parasite resistance and randomly assigned to be fed 900 g/d of an alfalfa-based supplement (CON; = 10) or a SL-based supplement ( = 20) for 103 d. Supplements were formulated to be isonitrogenous and isocaloric and to meet trace mineral requirements. Within the SL group, individual lambs were administered either 5 mL water or 5 mL of water with 163.3 mg of sodium molybdate (SLMO). Serum was collected on d 28, 56, and 104; a liver sample was collected by biopsy on d 104 to determine concentrations of trace minerals. Data were analyzed using a mixed model and orthogonal contrasts. Serum concentrations of Mo increased in response to the drench and were greatest in SLMO lambs and then CON lambs and lowest in SL lambs ( < 0.001). Concentrations of Mo in the liver ( < 0.001) were similar between CON and SLMO lambs and were lower in SL lambs than other groups. Serum ( < 0.001) and liver ( = 0.013) concentrations of zinc (Zn) were reduced in both SL and SLMO lambs compared with CON lambs. Serum concentrations of cobalt (Co) increased in CON lambs compared with SL and SLMO lambs between d 0 and 56 but were similar on d 104 (diet × day, < 0.005) as with concentrations in the liver. Serum and liver concentrations of copper (Cu) were greatest ( < 0.001 and < 0.001, respectively) in CON lambs followed by SL lambs and then SLMO lambs. Serum concentrations of selenium (Se) tended ( = 0.10) to be reduced in SL lambs compared with CON and SLMO lambs, but concentrations in the liver were reduced in SL lambs compared with CON lambs and even more so in SLMO lambs ( < 0.003). Although the dietary Mo did increase stores of Mo in the animal and reduced copper, trace minerals associated with metalloproteins-Mo, copper, selenium, and zinc-were reduced in the liver of SL- and/or SLMO-fed lambs. These reductions could be associated with the lower weight gains previously observed after prolonged feeding of SL.

Effect of growth implant regimen on health, performance, and immunity of high-risk, newly received stocker cattle.

Growth implant efficacy may be affected when administered to nutritionally stressed calves, whereas the procedure may alter health or the humoral immune response to respiratory vaccination. The study objective was to determine the effect of different administration times (d 0, 14, or 28) of a growth implant containing 200 mg progesterone and 20 mg estradiol benzoate on health, performance, and metabolic and immunologic variables in high-risk, newly received beef calves used in a 120-d receiving/grazing stocker system. Crossbred bull and steer calves ( = 203) were weighed (initial BW = 203 ± 2.7 kg), stratified by castrate status on arrival, and randomly assigned to experimental treatments consisting of 1) negative control (no growth implant administered), 2) growth implant administered on d 0, 3) growth implant administered on d 14, and 4) growth implant administered on d 28. There were no differences ( ≥ 0.16) in BW or ADG during the 42-d receiving period. However, ADG during the subsequent grazing period and overall was greater ( ≤ 0.01) for implanted calves versus the negative control. Growth implant timing did not affect the rate of clinical bovine respiratory disease morbidity ( = 0.52; 94% morbidity overall) or bovine viral diarrhea virus type 1a antibody titer concentration ( = 0.61). Indicative of an overall negative energy balance on arrival, NEFA decreased sharply subsequent to d 0 (day effect, < 0.001), but was not affected ( = 0.47) by the timing of growth implantation. Blood urea N concentrations increased transiently (day effect, < 0.001); however, no treatment effect was observed ( = 0.72). Therefore, under conditions of this study, the timing of growth implant administration did not affect growth implant efficacy, health, or metabolic or immunologic variables in newly received, high-risk beef stocker calves. Overall, our observations suggest that there is not a clear benefit to delaying growth implantation and that a growth implant does not affect health or vaccine response in newly received beef calves.

Weaning management of newly received beef calves with or without continuous exposure to a persistently infected bovine viral diarrhea virus pen mate: effects on rectal temperature and serum proinflammatory cytokine and haptoglobin concentrations.

Exposure to animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) results in immunomodulation in cohorts. It is hypothesized that the extent of modulation differs for low-risk, preconditioned (PC) vs. high-risk, auction market (AM) beef cattle. Our objective was to compare immune responses of PC or AM calves in the presence (PI) or absence (CON) of a PI-BVDV pen mate. Crossbred PC steers (n = 27) from a single ranch origin were weaned, dewormed, vaccinated against respiratory and clostridial pathogens, tested for PI-BVDV, and kept on the ranch for 61 d. Subsequently, PC steers were transported to a receiving unit (RU), weighed, stratified by d -1 BW, and assigned randomly to treatment (PCPI or PCCON) with no additional processing. Simultaneously, crossbred AM calves (n = 27) were assembled from regional auction markets and transported to the RU. The AM calves were weighed, stratified by gender and d -1 BW, processed under the same regimen used for PC steers at their origin ranch, except bull calves were castrated, then assigned randomly to treatment (AMPI or AMCON). Treatment pens were arranged spatially so that PI did not have fence line contact with CON. Blood samples were collected on d 0, 1, 3, 7, and 14 to determine serum concentrations of haptoglobin (Hp), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), IL-4, and IL-6. Rectal temperature (RT) was recorded concurrent with blood sampling. In AM calves, RT and Hp increased (management effect; P < 0.001) sharply on d 1; however, exposure to a PI-BVDV pen mate did not affect either variable (P ≥ 0.79) during the 14-d evaluation period. Serum concentrations of TNF-α tended to increase (P = 0.09) for the PI cohort. A treatment × day interaction (P ≤ 0.05) was observed for IFN-γ on d 7 and 14 and IL-6 on d 14; these indices were greatest for AMPI. Results indicate weaning management and PI-BVDV exposure alter the immune status of newly received beef cattle. These main effects may be additive because proinflammatory cytokine concentrations were greatest for AMPI. Therefore, results further indicate that potential health or growth consequences in cohorts exposed to a PI-BVDV pen mate are impacted by previous management and health history.

Feeding feedlot steers fish oil alters the fatty acid composition of adipose and muscle tissue.

Sixteen steers (441±31.7kg initial body weight) consumed two high concentrate diets with either 0 or 3% fish oil to determine the impact of fish oil, an omega-3 fatty acid source, on the fatty acid composition of beef carcasses. Collected tissue samples included the Longissimus thoracis from the 6th to 7th rib section, ground 10th to 12th rib, liver, subcutaneous adipose tissue adjacent to the 12th rib, intramuscular adipose tissue in the 6th to 7th rib sections, perirenal adipose tissue, and brisket adipose tissue. Including fish oil in the diet increased most of the saturated fatty acids (P<0.01) and proportions of polyunsaturated fatty acids (P<0.06), and decreased (P<0.01) proportions of monounsaturated fatty acids. Dietary fish oil increased (P<0.01) levels of omega-3 fatty acids in sampled tissues, resulting in lower (P<0.01) omega-6:omega-3 ratios. The weight percentages of C20:5 and C22:6 in tissue may provide the recommended daily allowance for humans. Fish oil may have a role in beef niche marketing if there are no deleterious effects on consumer satisfaction.

Influence of fish oil in finishing diets on growth performance, carcass characteristics, and sensory evaluation of cattle.

Inclusion of fish oil, a source of n-3 fatty acids, in ruminant diets may fortify the fatty acid composition of meats and alter consumer perceptions of taste. Therefore, a 70-d study of 16 crossbred steers (441 +/- 31.7 kg of initial BW; 4 steers/pen; 2 pens/dietary treatment) consuming a high concentrate diet was conducted. Dietary treatments consisted of 1) control (75% corn, 11% soybean meal, and 10% cottonseed hull-based diet) and 2) the control diet with 3% fish oil replacing a portion of the corn. Steers were weighed on consecutive days at d 0 and 70 (i.e., the beginning and end of the trial), and interim weights were taken on d 28 and 56. On d 63, all steers were bled by jugular venipuncture to determine plasma fatty acid profiles. Steers were stratified by treatment and slaughtered on d 71 and 72. Fish oil supplementation decreased ADFI (13.97 vs. 11.49 kg; P < 0.01); however, it had no effect on ADG (P = 0.20) or G:F (P = 0.27). Fish oil supplementation increased (P < 0.01) the concentrations of MUFA, as well as linolenic and eicosapentaenoic acid in the plasma. Fish oil supplementation did not alter (P > 0.24) the color of the LM, LM area, yield grade, dressing percent, marbling, quality grade, or fat thickness. However, after extended (15 mo) storage at -20 degrees C, a professional descriptor panel discerned steaks from steers that had been supplemented with fish oil from a commercially available product or steaks from control steers. In summary, supplementation with fish oil decreased feed intake and subsequent HCW (P = 0.06) and had varying effects on sensory traits. Nevertheless, fish oil supplementation increased the proportions of n-3 fatty acids in the plasma, which may increase acceptability of the meat to the beef consumer.

Influence of fish oil supplementation on growth and immune system characteristics of cattle.

A study was conducted to determine the effects of supplemental fish oil on growth performance and immune system characteristics of beef calves. The grazing phase (78 d) used 48 yearling crossbred steers (231 +/- 22 kg initial BW) grazing 0.45-ha mixed-grass pastures (four per treatment) supplemented with 1.82 kg/d (as-fed basis) of the diets. Diets consisted of 1) corn-based supplement; 2) corn-based supplement with 1.5% (as-fed basis) fish oil; 3) wheat midd-based supplement; and 4) wheat midd-based supplement with 1.5% fish oil. On d 78, all calves were bled by jugular venipuncture, and blastogenic response of peripheral blood lymphocytes to phytohemagglutinin, concanavalin A, and pokeweed mitogen was measured. Fish oil supplementation negatively affected ADG with the corn-based supplement, but it had no effect when added to the wheat midd-based supplement (base-supplement x fish oil interaction; P < 0.03). Isolated lymphocytes from calves fed the corn-based supplement with fish oil had a greater response to stimulation with concanavalin A than did lymphocytes from calves fed the corn-based supplement alone, but there was no effect of fish oil addition to the wheat midd-based supplement (base-supplement x fish oil interaction; P < 0.01). During the growing phase, the 48 steers (352 +/- 32 kg initial BW) from the grazing phase were moved to drylot pens and were stratified by BW and previous dietary treatment (three calves per pen; eight pens per dietary treatment) for a 56-d growing trial. Dietary treatments consisted of 1) control, and 2) the control diet with 3% (as-fed basis) fish oil. Calves supplemented with fish oil had decreased ADG, ADFI, and G:F (P < or = 0.02) compared with controls. Fish oil supplementation during the grazing phase modulated the immune system; however, the decreased growth performance associated with fish oil in both trials may limit its practical use as an immune stimulant.

The effect of methionine and aflatoxin on immune function in weanling pigs.

To investigate the effect of aflatoxin (AF) and dietary methionine (MET) on immune responses of swine, a total of 288 pigs weaned at 21 d of age were allotted to 12 dietary treatments arranged in a 3 x 4 factorial arrangement in a randomized complete block design. Diets consisted of a corn-soybean meal diet (.95% lysine, .30% MET, and .32% cystine) containing either 0, 140, or 280 ppb of AF and supplemented with either 0, .15, .30, or .45% DL-MET. Immune response measurements were made after the pigs had received their diet for 3 wk. Antibody response to sheep red blood cells (SRBC) was measured 0, 7, and 14 d after i.m. injection of 2.5 mL of a 20% SRBC suspension. Total serum immunoglobulin (Ig) M and IgG were measured using an ELISA. In vivo cellular immunity was measured using a phytohemagglutinin (PHA) skin test. Skin thickness was measured 0, 6, 12, 24, and 36 h after s.c. injection of .1 mL of PHA (1.50 mg/mL). In vitro cellular immunity was measured using a lymphocyte blastogenesis assay. Antibody response to SRBC and serum IgM and IgG concentrations were not affected by dietary treatments. Skin thickness response at 6 h after injection was maximal when .45% MET was added to diets containing 280 ppb of AF, whereas the response was maximal at .30% supplemental MET for the 0 and 140 ppb of AF diets (AF x MET interaction, P < .10). Skin thickness was reduced linearly (P < .10) with increasing dietary AF at 12 and 24 h after PHA injection.(ABSTRACT TRUNCATED AT 250 WORDS)