Effect of simulated ambient particulate matter exposure on performance, rectal temperature, and leukocytosis of young Spanish goats with or without tilmicosin phosphate.

Dust is an environmental stressor and can become extensive in agricultural production systems. Thirty-six female, Spanish goats (average BW 21.1 kg, SEM = 1.31; age = 4 mo) were randomly assigned to simulated dust events or no dust, with or without tilmicosin phosphate treatment in a 2 x 2 factorial arrangement of treatments to determine effects on performance, rectal temperature, and leukocyte changes. All goats were fed a standard growing diet (13.6% CP) consisting of 37% roughage and 63% concentrate (DM basis). Feed intake was measured daily, and BW (unshrunk) measured individually every 7 d. The tilmicosin-treated group received tilmicosin phosphate (10 mg/kg BW s.c.) before starting the study. Goats exposed to dust were enclosed as a group inside a canvass tent for 4 h each day and ground feed yard manure dust (mean particle size 100 microm) was aerosolized inside the tent to simulate a dust event. There was one single dust event (Phase I) followed by rectal temperature measurement, and heparinized blood collection for complete cell counts at 0 (pretrial), 4, 12, 20, 44, 68, and 210 h after dust exposure. This was followed by 21 d of chronic dust events (Phase II). The sampling procedures for Phase II were exactly the same as in Phase I, except that samples were obtained daily at 0 (before dust application), 4, 8, and 12 h after each dust event. Dust treatment had no effect (P > 0.05) on feed intake or ADG, but the gain:feed (G:F) ratio was lower (P < 0.05) in the control goats than the dust exposed group. Tilmicosin phosphate-treated goats had a higher (P < 0.05) G:F ratio than untreated goats. Dust exposure increased (P < 0.002), but tilmicosin treatment decreased (P < 0.05) rectal temperature at 4 and 8 h. Dust exposure increased (P < 0.02) blood lymphocyte counts compared with controls. These results suggest that simulated dust events altered rectal temperature and leukocyte counts of goats.

Influence of clostridial vaccines and injection sites on performance, feeding behavior, and lesion size scores of beef steers.

Several clostridial vaccines are currently being used in the beef cattle industry. Of greatest concern is altering the location and route of administration of these vaccines to reduce injection-site lesions while maintaining seroconversion. Two experiments were conducted to determine the effect of clostridial vaccines and injection sites on the performance, feeding behavior, and lesion size scores of beef steers. In Exp. 1, 80 crossbred beef steers (BW 237 +/- 3.2 kg) were allotted randomly into five groups and given 14 d to adapt to the feed and individual feed intake-monitoring devices (Pinpointer devices) before starting the study. Each group was assigned randomly to one of the following vaccination treatments: 1) control (sterile saline water), 2) Alpha-7 Ear (A7E), 3) Alpha-7 Prescapula (A7P), 4) Vision-7 Prescapula (V7P), and 5) Ultrabac-7 Prescapula (U7P). All vaccines were injected s.c. in the ear or prescapular region, and injection sites were palpated on d 0 and 28 (Exp. 1) and on d 63 and 91 (Exp. 2). The protocol for Exp. 2 was exactly the same as for Exp. 1 except treatments included control, A7P, Alpha-CD Ear (ACDE), Alpha-CD Prescapula (ACDP), Fortress-7 Prescapula (F7P), and V7P. Also, control and steers receiving F7P and V7P were revaccinated on d 63 and palpated on d 91. Results of Exp. 1 indicated that the A7E and U7P steers had a feed intake lower (P < 0.01) than all other treatment groups. The ADG of the A7P and A7E steers were not different (P > 0.05) from those of the control steers. The gain:feed ratio of the A7E steers was 41% higher (P < 0.01) than that of the V7P steers (Exp. 1). The results of Exp. 2 indicated that the control, ACDP, and V7P steers had greater (P < 0.01) ADG than all other treatment groups, but the gain:feed ratios were not different (P > 0.05) among all treatment groups. Lesion sizes differed by vaccine and injection site in both experiments. These data suggest that vaccinating beef steers s.c. in the ear produced gain:feed ratios and lesion size scores that were similar to prescapular vaccinations. However, more research is required to determine the immune response of vaccinating cattle in the ear.

Recovery rate and plasma zinc and copper concentrations of steer calves fed organic and inorganic zinc and manganese sources with or without injectable copper and challenged with infectious bovine rhinotracheitis virus.

Two experiments were conducted using feeder calves in a randomized block design to determine the effects of organic and inorganic sources of Zn and Mn fed pre- and posttransit (Exp. 1 and 2) with or without injectable Cu (Exp. 2) on DMI, rectal temperature, BW changes, and plasma Zn and Cu concentrations of feedlot steers challenged with infectious bovine rhinotracheitis virus (IBRV). In Exp. 1, before weaning, all steers and their dams received the following free-choice mineral supplements: 1) control (no supplemental Zn or Mn), 2) ZnO+MnO (ZnMnO), and 3) Zn methionine+Mn methionine (ZnMnMet). In Exp. 2, 18 d before weaning and shipping, steers were allotted into two groups (22 steers/group) and fed 225 mg of Zn.steer-1 x d-1 in .9 kg of ground corn as ZnO or ZnMet. Half of the steers from each group were injected (s.c.) with 120 mg of Cu from Cu glycinate. Steers (Exp. 1 and 2) were weaned and shipped approximately 2,500 km to the feedlot, where they received the same supplements in the form of a complete diet for 34 d, during which time calves recovered from the stress due to shipment. All steers were initially sero-negative to IBRV. On d 34 (d 0 of IBRV), all steers were challenged with IBRV and DMI, rectal temperature, and BW change were monitored for 28 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Feed intake, rectal temperature, and serum mineral concentrations of feedlot cattle fed zinc oxide or zinc methionine and challenged with infectious bovine rhinotracheitis virus.

Three experiments were conducted using feedlot steers in a randomized block design to determine the effect of zinc methionine (ZnMet) and zinc oxide (Exp. 3) on feed intake (DMI), rectal temperature, and serum mineral concentrations of feedlot cattle challenged with infectious bovine rhinotracheitis virus (IBRV). All the steers used were seronegative to IBRV. Steers were adapted for 7 d to their respective diets and challenged with 3.7 x 10(5) plaque forming units of IRBV on d 0 of each experiment. Live BW, rectal temperature, and individual daily DMI were recorded for 14 d. Blood samples were taken on d 0, 7, and 14. In Exp. 1, daily DMI of the control steers (Zn = 31 ppm) decreased 50% compared with 15% in the ZnMet (Zn = 90 ppm) steers 3 d after IBRV challenge. By d 6, the ZnMet steers had regained their pretrial mean daily DMI, but the control steers took 11 d. The ZnMet steers had lower (P less than .05) mean rectal temperature than the control steers on d 7 and 12. In Exp. 2, the control (Zn = 35 ppm) steers had lower (P less than .05) daily DMI on d 8 to 12 than the ZnMet (Zn = 89 ppm) steers. In Exp. 3, the mean decrease in daily DMI tended to be more rapid in the ZnO steers than in the control and ZnMet steers. All steers had the lowest daily DMI on d 5 and 6, coinciding with the highest rectal temperature. Serum Zn, P, and Mg concentrations decreased and serum Cu increased in all steers after infection. These data suggest that dietary Zn enhanced the recovery rate of IBRV-stressed cattle.

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

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

Performance and carcass quality of steers supplemented with zinc oxide or zinc methionine.

Forty-five Angus steers (avg initial wt 330 kg) were individually fed for 112 d to assess the value of supplemental Zn and source on performance and carcass quality. Steers had ad libitum access to a control diet (81 ppm Zn) of 33% whole corn, 33% ground milo, 15% cottonseed hulls and 13% cottonseed meal, or this control diet with 360 mg Zn/d added from either zinc methionine or zinc oxide. Steers were slaughtered on d 114, and carcass composition was determined by specific gravity. Average daily gain and feed efficiency were not affected by dietary treatments. Steers fed zinc methionine had a higher (P less than .05) USDA quality grade than those fed the control and zinc oxide diets. Marbling score was higher (P less than .05) for steers fed zinc methionine than for those fed control and zinc oxide treatments (4.4 vs 4.0 and 4.0, respectively, where 3 = slight, 4 = small, 5 = modest). Steers fed zinc methionine tended to have more (P less than .10) external fat (13 mm) than steers fed the control diet (10 mm); steers supplemented with zinc oxide had intermediate amounts of external fat (11 mm). Steers fed zinc methionine had 10.5 and 12.8% more (P less than .05) kidney, pelvic and heart (KPH) fat than steers fed control or zinc oxide diets, respectively. The effects of zinc methionine on carcass quality grade and marbling score may be due to Zn and (or) methionine. Regardless of the mechanism, the difference represents a potential economic benefit to producers.

Effect of magnesium and potassium on microbial fermentation in a continuous culture fermentation system with different levels of monensin or lasalocid.

Two continuous culture fermentation experiments were used to determine ruminal microbial fermentation in the presence of monensin (Exp. 1) or lasalocid (Exp. 2) with different dietary concentrations of Mg and K. In each experiment, eight 500-ml continuous culture fermentors were supplied with late-cut coastal bermuda grass (80%) and cellulose (20%) as substrate during five trials with two levels of Mg (.07 and .14%), K (.6 and 2.5%) and either monensin (Exp. 1; 0 and 20 mg/kg) or lasalocid (Exp. 2; 0 and 20 mg/kg) in a 2 x 2 x 2 factorial arrangement of treatments (each trial served as a replication). Substrate was added every 8 h (5 g/fermentor) for 5 d and digesta samples were collected every 2 h for 6 h and at 20 h for volatile fatty acid (VFA) analysis on d 6. In Exp. 1, monensin decreased (P less than .05) the acetate:propionate ratio (A:P) from 2.98 to 2.22. A Mg X monensin interaction was observed for the molar percentage of acetate and propionate (P less than .05). There was a 4.8% reduction in acetate (mol/100 mol) when monensin was fed with .07% Mg and a 12.6% decrease (P less than .01) when fed with .14% Mg compared with diets not containing monensin. Propionate (mol/100 mol) increased 14% when monensin was fed with .07% Mg and 32% (P less than .001) when fed with .14% Mg compared with diets not containing monensin. Potassium did not affect VFA concentrations in the presence of monensin or Mg. In Exp. 2, lasalocid decreased (P less than .01) the A:P ratio from 3.53 to 2.86.(ABSTRACT TRUNCATED AT 250 WORDS)