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The objective of this study was to determine the effect of including soy co-products (soybean meal and soy oil) in the diet on the hemocytology of cattle after an endotoxin challenge. For the growing phase, crossbred Angus steers (n = 36; initial body weight = 289 ± 31 kg) were stratified by body weight and sire and randomly assigned to pastures (n = 9; 0.45 ha mixed grass). Pastures were assigned randomly to 1 of 3 dietary treatments: 1) a control supplement containing no soy co-products (CON); 2) a supplement containing soybean meal (SBM); or 3) a supplement containing soy oil (SBO). All supplements were isonitrogenous and isoenergetic. Cattle were fed supplements (2.45 kg DM/day) for 56 days. At the conclusion of the growing phase, cattle were assigned randomly to 1 of 2 groups for a lipopolysaccharide (LPS) challenge (i.v. infusion of 0.5 µg LPS/kg of body weight). A minimum of 18 hours before sampling, cattle were fitted with jugular vein catheters and placed into stanchions. Blood was collected starting 2 hours before LPS infusion (-2 hr), immediately prior to LPS infusion (0 hr), and at 2, 4, 6, and 8 hr. Statistical analyses were performed using the MIXED procedure of SAS 9.4 as repeated measures with treatment, time, and treatment × time interaction as fixed effects, challenge group as random effect, and calf specified as the subject. Statistical significance was declared at P = 0.05 and tendencies declared at 0.05 < P = 0.1. There were treatment × time interactions for neutrophils (P = 0.003), percentage of neutrophils (P = 0.002), percentage of lymphocytes (P = 0.006), and neutrophil/lymphocyte ratio (NE:LY ratio; P = 0.001). Briefly, neutrophils, percentage of neutrophils, and NE:LY ratio were decreased in cattle on CON diets compared with SBM at -2 h and 0 h (P < 0.01). Also, the percentage of neutrophils were greater at 8 h for cattle on SBO diets than SBM diets (P = 0.018). The percentage of lymphocytes were greater in cattle on the CON diets compared with the SBM diets at 0 and -2 h (P < 0.015). There was a treatment effect for percentage of monocytes (P = 0.035), as the CON diet had greater monocyte percentage compared with the SBM diet, and the SBO diet tended to have greater monocyte percentage compared with SBM diet. There was a time effect for all other hematology variables (P < 0.0001), as leukocytes were typically greater pre-administration of LPS, sharply decreased at 2 and 4 h post-administration of LPS and began to increase at 6 and 8 h. Preliminary results indicated that the inclusion of soy co-products in growing cattle diets influenced hemocytology. [ABSTRACT FROM AUTHOR]

The objective was to determine the effect of soy co-products (soybean meal and soy oil) in the diet on the growth and hemocytology of cattle during a 56-day growing phase and the physiological/behavioral response to an endotoxin challenge. Angus crossbred steers (n = 36; 289 ± 31 kg, initial body weight ± SD) were stratified by body weight and sire; and assigned randomly to pastures (n = 9; 0.45 ha/mixed-grass pasture). Pastures were assigned randomly to of 3 dietary treatments: 1) a control supplement containing no soy co-products, 2) a supplement containing soybean meal, or 3) a supplement containing soy oil. All supplements were isonitrogenous and isoenergetic. Cattle were fed supplements (2.45 kg DM/day) for a period of 56 days during which weight and blood samples for complete blood count (CBC) were taken every 14 days. At the conclusion of the growing phase, cattle were assigned randomly to of 2 challenge groups (conducted 6 days apart) for a lipopolysaccharide (LPS) challenge (i.v. infusion of 0.5 µg LPS/kg of body weight). A minimum of 18 hours before sampling, cattle were fitted with jugular vein catheters and placed into stanchions. Sickness behavior scores and rectal temperatures were collected every 30 minutes for a duration of 8 hours following LPS infusion. Body weights were analyzed using pen means and the MIXED procedure of SAS specific for repeated measures with treatment, day, and the treatment × day interaction as fixed effects and replicate as a random effect. CBC were analyzed using the MIXED procedure of SAS specific for repeated measures with treatment, day, and the treatment × day interaction as fixed effects, replicate as a random effect, and pen specified as the subject. Rectal temperatures and behavior scores were analyzed using the MIXED procedure of SAS specific for repeated measures with treatment, time, and the treatment × time interaction as fixed effects and challenge group as a random effect with calf as the subject. Dietary inclusion of soy co-products did not affect the body weights of steers for the 56-day growing phase (treatment and treatment × day, P = 0.20), nor were any hemocytology measurements affected (treatment and treatment × day, P = 0.12) during the growing phase. Following the endotoxin challenge there was no effect of treatment or treatment × time (P = 0.57) for rectal temperatures or sickness behavior scores. Therefore, preliminary results indicate that inclusion of soy co-products in cattle diets did not affect growth or complete blood counts during a 56-day growing phase, neither did diet affect body temperature or sickness behavior in response to an endotoxin challenge. [ABSTRACT FROM AUTHOR]

The objective was to evaluate growth performance and estimates of body composition in offspring of dams that consumed diets containing tall fescue seed with (E+) or without (E-) the toxic endophyte and with or without melatonin during mid-late gestation. Pregnant heifers (n = 57) artificially inseminated with sex-sorted semen (X chromosome-bearing sperm) from a single Angus sire were administered dietary treatments in a 2 x 2 factorial treatment arrangement (E-without melatonin, E-/NM; E-with melatonin, E-/M; E+ without melatonin, E+/NM; or E+ with melatonin, E+/M; melatonin dose: 100 µg/kg of BW) for a 70-day period between May and July starting at 160±13 d of gestation to mimic ergot alkaloid concentrations in a grazing scenario. All diets contained corn gluten and molasses and were fed using SmartFeed Pro (C-Lock Inc.) controlled feeding units between 0900 and2 1200 h daily. Cattle were removed from dietary treatments 39 ± 19 d before calving. Two replicates were housed separately in an open-air barn, each with a 1.2-ha paddock. Prior to and following the 70-d treatment period, all cattle were maintained as a single group free from toxic fescue. Calves were weaned at 226 ± 19 d of age. Gestation length, calf birth weight, 205-day adjusted weaning weight (205-d WW), carcass ultrasonography measures (ribeye area, REA; REA/CWT; percent intramuscular fat, IMF; rib fat thickness, UFAT; rump fat thickness, URUMP), postweaning weights (recorded every 28 d between weaning and 84 d post-weaning), and post-weaning ADG (between weaning and 84 d post-weaning) were evaluated in offspring (n = 44). Post-weaning calf weights were analyzed using the MIXED procedure of SAS specific for repeated measures with treatment and time as fixed effects and replicate as random. All other variables were analyzed using the MIXED procedure of SAS with treatment as a fixed effect and replicate as random with gestation length as a covariate for birth weight. Gestation length, birth weight, 205-d WW, and postweaning calf weight were decreased (P < 0.04) in offspring of dams that consumed E+ relative to E-during gestation. Birth weight was increased (P = 0.02) in offspring of dams receiving melatonin relative to those without melatonin during gestation. The 205-d WW and REA were decreased in calves born to E+/NM dams relative to E-/NM, E-/M, and E+/M (P < 0.03). Post-weaning weight tended to be decreased in calves born to E+/NM dams relative to E-/NM, E-/M, and E+/M (P = 0.06). The UFAT tended to be decreased (P = 0.06) in offspring of dams that consumed E+ relative to E-during gestation. There were no other effects of treatment, time or the interaction (P > 0.10). To our knowledge, these preliminary results are the first to evaluate the potential of melatonin as a therapeutic to recover performance losses in offspring born to pregnant cattle consuming toxic fescue. [ABSTRACT FROM AUTHOR]