Efficacy of a novel intranasal Zn solution on health and growth performance of high risk, newly received stocker cattle

Abstract Text: The objective of this study was to determine if using an intranasal Zn solution would impact health and growth performance of high-risk stocker cattle.  Upon arrival from regional sale barns, male beef calves (n = 239; 3 arrival dates [block]; initial BW = 276 ± 2.4 kg) were identified with individual ear tags, vaccinated with clostridial and 5-way modified live bovine respiratory viral vaccines, dewormed, branded, and castrated (if necessary). In addition, nasal swabs were collected from 24 calves (12/treatment) in block 2 and cultured for bacterial pathogens on d 0, 1, 2, and 7. Calves were stratified by arrival gender and BW into 2 treatments: Zn treated, 3 ml of a solution containing 32.4 mg of Zn administered intranasally, or control, in which calves were not treated. Calves were penned without fenceline contact to calves on the other treatment in replicated 0.42-ha grass pastures (24 pens) and cattle had ad libitum access to bermudagrass hay along with receiving a grain supplement to meet or exceed their nutritional requirements. Rectal temperatures were taken on d 0, 1, 7, and 14 after arrival. Calves were observed daily for signs of morbidity and a Clinical Illness Score (CIS 1 [normal] to 5 [morbid]) was recorded. Cattle that scored > 1 on the illness score and had a rectal temperature greater ≥ 40°C were treated with an antibiotic per a preplanned treatment protocol.  If rectal temperature ≥ 40°C persisted past first antibiotic post-treatment interval, cattle were re-treated according to pre-planned protocol. Body weights were similar across treatments throughout the duration of the study (P ≥ 0.22). Calves treated with Zn had a lower ADG from d 7 to 28 and d 14 to 28 compared to the control (P < 0.01). Control calves tended to be treated with 3 antibiotics more often than Zn treated calves (P = 0.06). Overall treatment antibiotic costs did not differ across treatments (P = 0.64). There were no differences (P ≥ 0.10) for rectal temperature of calves across treatment. The prevalence of bacterial pathogens were not different across treatments (P ≥ 0.24) except the presence of P. aeruginosa which tended to be greater in the control compared to the Zn treated calves (P = 0.08). From the results of this study, calves treated intranasally with Zn showed no differences in overall performance and minimal differences in morbidity compared to the control.

Keywords: bovine respiratory disease, morbidity, Zn