Application of NIRS Fecal Analysis for Tick Management on Range Cattle

NON-TECHNICAL SUMMARY: Current decision-aids in IPM programs for ectoparasites of range cattle are based on association of parasite numbers to animal weight loss, body condition, or decreased growth potential. Count data for parasites such as ticks require animals be individually examined. This is an economic and managerial disincentive to adoption and effective application of IPM practices. Producers often focus their treatments on a convenient seasonal schedule of ranching activities regardless of pest presence or abundance. Detection and treatment of certain parasites are completely missed using these methods. Less intrusive, less labor-intensive, and more cost-effective methods of parasite detection are needed to improve decision-making and monitoring overall animal health. We have discovered that fecal chemistry of tick infested cattle and horses under controlled conditions changes between non-infested and infested conditions as determined with NIRS fecal analyses. This project will examine whether fecal chemistry changes are detecting changes in digestive system response to the stress of tick bloodfeeding, and whether NIRS technology could be used to identify tick infested cattle under field conditions. <P>

APPROACH: We will examine NIRS fecal chemistry responses of artificially tick-infested cattle placed on two dietary levels and the potential influence of key immune and endocrine components. Beef steers will be infested with lone star ticks and monitored through phases of tick attachment, engorgement, drop and post-infestation. Daily fecal samples collected throughout the study will be analyzed by NIRS, and will provide dietary components for digestible organic matter, crude protein, degraded intake protein, digestible un-degraded protein, and indigestible intake protein, as well as fecal nitrogen and phosphorous. The NIRS fecal chemistry will be analyzed with respect to actual tick burden, date, tick feeding phase, and serum concentrations of growth related hormones and metabolites, and fecal dietary components. These analyses will help determine whether we can accept the hypothesis that cytokine-endocrine mediated host-parasite responses result in fecal chemistry changes from tick infestations, and provide the necessary basis for associating NIRS fecal analyses with parasite burden.
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PROGRESS: 2004/08 TO 2006/08<BR>
Exteral parasite burdens have been reported to depress dry matter intake in cattle while influencing metabolic indicators such as IGF-1. The adverse effects of a tick-burden could be amplified in animals consuming a low quality diet, as might be expected under range conditions. This project evaluated 28 growing beef steers randomly assigned to one of four treatments in a 2x2 factorial experiment: moderate(14% CP, 60% TDN)vs low (7%CP, 58%TDN) plane of nutrition, and tick infested (300 pair of lone star ticks) vs control (no ticks). Steers were fed respective diets for 35 days prior to, and 21 days following the start of tick infestation (day 0), with peak tick feeding occuring 10-14 days post tick infestation. Fecal samples were collected daily and frozen for analysis, and blood was sampled on days -7,0,7,8,9,10,11,13,17, and 21, and analyzed for IGF-1 by radio-immuno assay. There was no difference in animal weight at day -35, but on day 0 steers on the moderate diet weighed more than those on the low diet, and by day 21 the difference in weights were even more pronounced. DMI was greater (P<0.05) in moderate than low plane of nutrition (PON) and also greater in tick control than in tick infested cattle. Within PON, DMI was greater (P<0.05)in tick control than in tick infested cattle for both moderate and low PON. IGF-1 was greater (P<0.05) in moderate than low PON and in tick control compared to tick infested animals. Within the moderate PON, there was no difference in IGF-1 between tick infested and control animals. However, within the low PON, IGF-1 was greater (P<0.05) in tick control animals than in tick infested animals. During peak tick feeding (days 10-13) IGF-1 was greater (P<0.05) in tick control than in tick infested animals. Fecal samples from low PON animals had increased (P<0.05) DM and OM compared to those from moderate PON animals. There were no differences in fecal DM or OM between tick control and infested animals. Within PON, fecal DM and OM was greater (P<0.05) for tick control animals than for tick infested animals. There were no differences for DM and OM between tick control and infested animals. There were no observed differences in pH among and between PON and treatment groups. Tick burden affected dietary intake and metabolism in growing cattle and was exacerbated by a low plane of nutrition. Fecal DM and OM were similarly affected by PON or tick treatment. Fecal analysis by NIRS has been completed and further analyses of interactions between fecal chemistry and blood parameters are pending.
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IMPACT: 2004/08 TO 2006/08<BR>
We expect to determine the interaction of parasite stress and nutrition on growing cattle, and to determine if fecal or blood paramters can be used to monitor these effects. If successful, these techniques could be applied to management recommendations and/or treatment monitoring in free ranging cattle.