Sensor technologies can identify modified animal activity indicating changes in health status. This study investigated sheep behavior before and after illness caused by mold-contaminated feed using tri-axial accelerometers. Ten ewes were fitted with HerdDogg biometric accelerometers. Five ewes were concurrently fitted with Axivity AX3 accelerometers. The flock was exposed to mold-contaminated feed following an unexpected ration change, and observed symptomatic ewes were treated with a veterinarian-directed protocol. Accelerometer data were evaluated 4 days before exposure (d −4 to −1); the day of ration change (d 0); and 4 days post exposure (d 1 to 4). Herddogg activity index correlated to the variability of minimum and standard deviation of motion intensity monitored by the Axivity accelerometer. Herddogg activity index was lower (p < 0.05) during the mornings (0800 to 1100 h) of days 2 to 4 and the evening of day 1 than days −4 to 0. Symptomatic ewes had lower activity levels in the morning and higher levels at night. After accounting for symptoms, activity levels during days 1 to 4 were lower (p < 0.05) than days −4 to 0 the morning after exposure. Results suggest real-time or near-real time accelerometers have potential to detect illness in ewes.
Behavior can be a valuable indicator of an animal’s health and wellness state, emphasizing the importance of monitoring changes in behavior. Sensor technologies can identify changes in animal activity, providing the potential to detect abnormal behavior associated with health status and animal welfare. The aim of this study was to investigate sheep behavior before and after illness caused by mold-contaminated feed using tri-axial accelerometers. Twenty-five ewes were fitted with HerdDogg biometric accelerometer ear tags. Thirteen ewes also had Axivity AX3 accelerometers attached on the opposite side ear tag. Tri-axial accelerometers were attached to mature ewes for the purpose of parturition evaluation, when an unexpected ration change occurred. The entire sheep flock was exposed to mold-contaminated feed, symptoms were immediately observed, and symptomatic ewes were treated with a veterinarian directed protocol. Accelerometer data were evaluated 4 days prior to exposure (d -4 to -1); on day of ration change (d 0); and 4 days post exposure (d 1 to 4). Herddogg accelerometer data from 3 ewes displaying symptoms identified a decrease in activity (P ≤ 0.03) for 2 days after feed exposure compared to the 4 days before exposure. Three days after exposure and 2 days after treatment, no difference in activity was detected (P > 0.05) between pre- and post-activity levels. Herddogg accelerometers can identify similar behavioral changes as Axivity accelerometers. The correlation of the standard deviation of movement intensity derived from the Axivity accelerometer and the Herddogg activity metric was 0.67. It is crucial to detect subtle behavioral changes at onset of illness, to allow for prompt producer intervention before animal health is compromised. These results suggest that real-time or near-real time accelerometers, such as Herddogg, have potential to detect illness in ewes in a pen setting.
The immunostimulatory and toxic effects of extracellular histones have been demonstrated in humans and rodents suffering from acute respiratory distress syndrome and acute lung injury. Accumulating evidence suggests intricate interactions between extracellular histones and immune complement system proteins occur as a regulatory mechanism. However, limited information is available on the interactions of complement system activity and histone toxicity during immunomodulatory events in livestock. Therefore, our current research is aimed at investigating the contributions of histone toxicity and complement system activity in relation to respiratory disease and pregnancy in wild and domestic sheep and cattle. In an initial study, feedlot heifers were evaluated for protective capacity against extracellular histones and complement activity related to subsequent disease outcomes. At feedlot arrival, serum samples were collected from 118 heifer calves (BW 229 ± 2.4 kg) and subjected to a histone toxicity assay and a 50% hemolytic complement activity assay. Heifers were retrospectively assigned as either never receiving treatment with antibiotics for bovine respiratory disease (NT; n = 80) or calves that died from bovine respiratory disease within 1 wk of entering the feedlot (DA; n = 9). Serum from DA animals was less (P < 0.001) protective against histone toxicity compared to NT heifers. Likewise, complement activity of DA animals was reduced (P < 0.05) compared to NT animals. These results suggest cattle predisposed to severe cases of respiratory disease have impaired complement system activity presumably leading to reduced protection against histone toxicity. In a second study, wild Alaskan Dall sheep (Ovis dalli dalli) and domestic sheep (Ovis aries) were evaluated for susceptibility to histone toxicity. Serum was collected from Debouillet sheep (n = 150) with no clinical signs of illness and serum of wild Alaskan Dall sheep (n = 135) was collected from live capture and release animals. Dall sheep serum was less (P < 0.05) protective against histone toxicity compared to Debouillet sheep. Low protection against histone toxicity may be related to higher reported disease states for wild sheep. Furthermore, recognizing that disease modulates immune function, it is also recognized pregnancy relies on immune system activation. Therefore, pregnant sheep serum was evaluated to determine the effect of histone toxicity and complement system activity. Serum was collected from Debouillet ewes (n = 8) and analyzed for histone toxicity protectiveness and complement activity. Serum was collected from ewes prior to breeding (d -0) and at d 1 and 17 of the estrous cycle. Serum protective capacity against histones and complement activity was not significantly different on d -0 compared to d 1 and d 17. Collectively, these data implicate the toxic effect of extracellular histones and complement system activity during respiratory disease states with less obvious observations during pregnancy.
With the decrease of a wool favored market, hair type sheep have become increasingly popular for lamb markets. In Texas, the most popular hair type breed of sheep is the Dorper. Various breed characteristics make the Dorper sheep an excellent candidate for an accelerated lambing system. Reproductive performance of Dorper ewes with various lengths of post-partum interval, during the traditional non-breeding season, was determined. During May (13L:11D), 2+ yr-old multiparous ewes (n = 28) were joined with a fertile ram for 30 d. Weekly blood samples were taken for progesterone analysis. Ewes were blocked according to length of post-partum interval (lamb to ram): short (SPP; n = 10, 100 ± 2.7 d), mid (MPP; n = 11, 130 ± 0.68 d) and long (LPP; n = 7, >200 d). Weaning age of lamb(s) from previous parturition was similar for SPP (62 ± 3.2 d) and MPP (67 ± 0.6 d). Interestingly, 11% of the ewes had a functional CL at initiation of the study (P4 > 1.5 ng/mL). Mean body condition score for SPP, MPP, and LPP ewes were 2.8 ± 0.08, 3.1 ± 0.09, and 3.7 ± 0.08, respectively. Pregnancy rates were similar between MPP (100%), LPP (100%) and SPP (60%). Overall, pregnancy rate was 87% and a lamb crop (lambs per ewe exposed) was 1.3 ± 0.09. Twinning rate for SPP, MPP, and LPP was 20%, 73%, and 43%, respectively. Pregnancy rate in SPP ewes may indicate carryover of the suppressive effects of lactation and suckling. Results suggest a lamb to ram interval of >100 d is sufficient for response to the ram effect and resumption of estrous cycles in a majority of ewes during photoperiod of 13L:11D. We conclude Dorper sheep have the reproductive capacity to successfully meet the production goals of accelerated lambing systems and thus, the potential for optimized lamb production.
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