The CowManager (Agis, Harmelen, the Netherlands) ear sensor technology was developed for dairy cows in confinement and has recently been adopted for pastured beef cows. The sensors fit around the ‘840’ RFID button and houses a 3-dimensional accelerometer that registers movement of the cow’s ear. Each sensor stores up to 7 d of internal data at a time and is transmitted by solar powered routers in the pasture. The objective was to determine the effectiveness of the CowManager system’s estrus detection (ED) feature in beef cows during estrous synchronization (ES), AI, and during exposure to bulls for 60 d. Fifty 6-8 yr multiparous commercial Angus-crossbred cows with calves, were fitted with CowManager ear sensors for 14 d to allow for acclimation. Cows then underwent ES using a 6-d CO-Synch + controlled internal drug release (CIDR) protocol with AI at 72 h post CIDR + prostaglandin F2α with sexed female semen. Estrus detection was determined using breeding patches (Estrotect™, Rockway Inc., Spring Valley, WI), with estrus classified as greater than 50% of color rubbed off, and CowManager sensors with a notification to a smartphone and/or computer. The CowManager sensors were effective in determining estrus in 92% (46/50) of the synchronized cows, and the first service conception rate was 74% (37/50). CowManager sensors detected 100% (37/37), and ESTROTECT patches detected 91% (34/37) of the cows in estrus that conceived by AI. During bull exposure, CowManager detected 100% (13/13) of estrus and the natural breeding dates were confirmed by ultrasound fetal aging. ESTROTECT patches were not used during exposure to bulls. However, CowManager detected 5 of the AI pregnant cows as in estrus during the exposure to bulls. CowManager’s ED feature was highly effective in determining estrus for beef cattle and was similar to breeding patches for ED.
The objective was to evaluate the influence of prenatal exposure to endophyte-infected tall fescue (toxic fescue) on postweaning glucose metabolism in crossbred steers. Pregnant multiparous cows (n = 36) were maintained on replicated novel or toxic fescue pastures throughout gestation and bermudagrass pastures following calving. From the subsequent calf crop, weaned steers (257±28 d of age) of similar body weight (234±32 kg Toxic; 236±44 kg Novel) were randomly selected (n = 8 Toxic; n = 7 Novel) for a glucose tolerance test. Steers were fitted with jugular vein catheters and fasted for a minimum of 12 h before intravenous administration of a 50% dextrose solution (0.5 mL/kg of body weight). Blood was collected at -10, 0, 10, 20, 30, 45, 60, 90, 120, and 150 min (0 min=glucose administration). Plasma glucose and serum insulin were determined by hexokinase colorimetric assay and radioimmunoassay, respectively. Glucose, insulin, and the insulin to glucose (I:G) ratio were analyzed using MIXED procedures of SAS specific for repeated measures with treatment as a fixed effect and sire as random. All other variables were analyzed using MIXED procedures of SAS with treatment as a fixed effect and sire as random. As expected, glucose, insulin, and the I:G ratio increased in response to glucose administration (time P < 0.01). There was no effect of treatment (P > 0.39) or the treatment by time interaction (P > 0.19) for glucose, insulin, or the I:G ratio. However, Toxic steers exhibited numerically increased glucose, decreased insulin, and decreased I:G ratios relative to Novel steers following glucose administration. There was no difference (P > 0.13) in baseline, peak, time at peak, or time at return to baseline concentrations for insulin or glucose. While prenatal exposure to toxic fescue did not influence glucose or insulin homeostasis in response to exogenous glucose administration in this preliminary study, numerical differences warrant future evaluation with increased animal numbers.
The objective was to investigate the influence of progesterone exposure time and breeding time on fixed-time artificial insemination (FTAI) protocols using sex-sorted semen in Angus-cross heifers (n = 85; mean BW = 324 kg.). Heifers were assigned randomly into four treatment groups. Treatments 1 and 2 used a 6-day CO-synch + controlled internal drug release (CIDR) protocol with gonadotropin releasing hormone (GnRH) administration and CIDR insertion on day 0 and prostaglandin F2α (PGF) administration on day 6, upon simultaneous CIDR removal. Treatment 1 heifers underwent FTAI 72 h post CIDR removal, and Treatment 2 heifers underwent FTAI 80 h post CIDR removal. Treatments 3 and 4 used a 7-d CO-synch + CIDR protocol with GnRH administration and CIDR insertion on d 0 and PGF administration on d 7, upon simultaneous CIDR removal. Treatment 3 heifers underwent FTAI 54 h post CIDR removal, and Treatment 4 heifers underwent FTAI 62 h post CIDR removal. Estrus expression was determined using an estrus detection patch (Estrotect™, Rockway Inc., Spring Valley, WI). Estrus expression was classified as a patch with 50% or more of the color rubbed off and the absence of estrus expression as a patch with less than 50% of the color rubbed off. All heifers were inseminated using female sex-sorted semen from a single Angus sire (SexedULTRA 4M™, STgenetics, Navasota, TX). Pregnancy was determined by ultrasound 57 d following FTAI. Pregnancy rates and patch scores were analyzed using the GLIMMIX procedure of SAS 9.4 with treatment as a fixed effect. There was no effect of treatment on the first service AI rates (P = 0.91) or on estrus expression (P = 0.17) in heifers. In conclusion, the combinations of progesterone and breeding time in this study did not affect first service AI conception rates or estrus expression in beef cattle heifers.
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