title: Plane of nutrition x tick burden interaction in cattle: effect on fecal composition.
abstract: Effective tick management on grazing animals is facilitated by accurate noninvasive detection methods. Fecal analysis provides information about animal health and nutrition. Diet affects fecal composition; stress may do likewise. The constituents in feces that may be affected by tick burdens and in turn affect near-infrared spectra have not been reported. Our objective was to examine the interaction between plane of nutrition and tick burden on fecal composition in cattle. Angus cross steers (n = 28; 194 ± 3.0 kg) were assigned to 1 of 4 treatments (n = 7 per group) in a 2 × 2 factorial arrangement: moderate (14.0 ± 1.0% CP and 60 ± 1.5% TDN) vs. low (9.0 ± 1.0% CP and 58 ± 1.5% TDN) plane of nutrition and control (no tick) vs. tick treatment [infestation of 300 pair of adult Lone Star ticks (Amblyomma americanum) per treated animal]. Fecal samples were collected at approximately 0700 h on d -7, 0, 7, 10, 14, 17, and 21 relative to tick infestation. Fecal constituents measured were DM, OM, pH, Lactobacillus spp., Escherchia coli, acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, IgA, and cortisol. Experimental day affected (P < 0.05) all constituents measured. Plane of nutrition affected (P < 0.05) DM, OM, VFA, and IgA. Tick treatment numerically (P = 0.13) reduced cortisol. A multivariate stepwise selection model containing cortisol and E. coli values on d 10 and d 14 accounted for 33% of the variation in daily adult female tick feeding counts across both planes of nutrition (P < 0.07). Within the moderate plane of nutrition, a model containing only cortisol on d 10 and d 14 described 59% of the variation in the number of feeding ticks (P < 0.02). Similarly, a model including cortisol, propionate, isovalerate, and DM at d 10 and d 14 d described 95% of the variation in total feeding ticks in the low plane of nutrition. Of the constituents measured, fecal cortisol offers the best possibility of noninvasively assessing stress by way of a single assay but the presence of ticks would still need to be confirmed visually. Although several constituents measured in this study should exist in sufficient quantity to directly affect near-infrared spectra, none stood out as a clear descriptor of prior observed differences in fecal spectra between tick-treated versus non-tick-treated animals. There were, however, groups of fecal constituents related to daily adult female tick feeding numbers (as a visual estimation of tick stress).
authors: School of Natural Resources and the Environment, The University of Arizona, Camp Verde 86322, USA. dougt@cals.arizona.edu
authors: D R
authors: DR
authors: Tolleson
authors: S D
authors: SD
authors: Prince
authors: K K
authors: KK
authors: Banik
authors: T H
authors: TH
authors: Welsh
authors: G E
authors: GE
authors: Carstens
authors: O F
authors: OF
authors: Strey
authors: P D
authors: PD
authors: Teel
authors: S T
authors: ST
authors: Willard
authors: M T
authors: MT
authors: Longnecker
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000473:pathology*; D004032:Diet / Q000662:veterinary; D005243:Feces / Q000737:chemistry*; D005260:Female; D008297:Male; D009752:Nutritional Status; D013984:Tick Infestations / Q000473:pathology / Q000662:veterinary*