Supplementing an immunomodulatory feed ingredient to improve thermoregulation and performance of finishing beef cattle under heat stress conditions

Abstract

This experiment compared physiological and productive responses in finishing beef cattle managed under heat stress conditions, and supplemented (SUPP) or not (CON) with an immunomodulatory feed ingredient (Omnigen-AF; Phibro Animal Health, Teaneck, NJ). Crossbred yearling cattle (¾ Bos taurus × ¼ Bos indicus; 64 heifers and 64 steers) were ranked by initial body weight (BW) (440 ± 3 kg) and sex, and allocated to 1 of 16 unshaded drylot pens (8 heifers or steers/pen). Pens within sex were randomly assigned to receive SUPP or CON (n = 8/treatment). Cattle received a total-mixed ration (91% concentrate inclusion and 1.21 Mcal/kg of net energy for gain; dry matter [DM basis]) during the experiment (day 0 to 106). The immunomodulatory feed was offered as a top-dress to SUPP pens (56 g/d per animal; as-fed basis) beginning on day 7. Cattle BW were recorded on day 0, 14, 28, 42, 56, 70, 84, 98, and 106. Feed intake was evaluated from each pen by recording feed offer daily and refusals biweekly. Intravaginal temperature of heifers was recorded hourly from day 1 to 6, 29 to 41, and 85 to 97. Environmental temperature humidity index (THI) was also recorded hourly throughout the experiment, and averaged 79.8 ± 0.6. Concurrently with BW assessment, hair samples from the tail-switch were collected (3 animals/pen) for analysis of hair cortisol concentrations. Blood samples were collected on day 0, 28, 56, 84, and 106 from all animals for plasma extraction. Whole blood was collected on day 0, 56, and 106 (3 animals/pen) for analysis of heat shock protein (HSP) 70 and HSP72 mRNA expression. Cattle were slaughtered on day 107 at a commercial packing facility. Results obtained prior to day 7 served as independent covariate for each respective analysis. Heifers receiving SUPP had less (P ≤ 0.05) vaginal temperature from 1500 to 1900 h across sampling days (treatment × hour, P < 0.01; 39.05 vs. 39.19 °C, respectively; SEM = 0.04), when THI ranged from 85.3 to 90.1. Expression of HSP70 and HSP72 was less (P ≥ 0.03) for SUPP cattle on day 106 (22.6- vs. 51.5-fold effect for HSP70, SEM = 9.7, and 11.0- vs. 32.8-fold effect for HSP72; treatment × day, P ≤ 0.04). No treatment effects were detected (P ≥ 0.22) for performance, carcass traits, plasma concentrations of cortisol and haptoglobin, or hair cortisol concentrations. Results from this study suggest that SUPP ameliorated hyperthermia in finishing cattle exposed to heat stress conditions, but such benefit was not sufficient to improve productive responses.

Impacts of commingling cattle from different sources on their physiological, health, and performance responses during feedlot receiving

“…On d 0 of the experiment, heifers were vaccinated against Clostridium (Covexin 8; Merck Animal Health, Madison, NJ), Mannheimia haemolytica , bovine respiratory syncytial virus , bovine herpesvirus-1 , bovine viral diarrhea virus 1 and 2 , and parainfluenza-3 virus (Vista Once SQ; Merck Animal Health), administered an anthelmintic (Safe-Guard, Merck Animal Health), and received a growth-promoting implant (Synovex-H; Zoetis, Florham Park, NJ). Heifers had free-choice access to water and the aforementioned starter feed (RAMP; Cargill Corn Milling) from d 0 to d 55, which was fed once daily (0800 hours) in a manner to yield 10% residual orts ( Colombo et al, 2019 ).…”

“…After collection, all blood samples were placed immediately on ice, centrifuged (2,500 × g for 30 min; 4 °C) for plasma or serum harvest, and stored at −80 °C on the same day of collection. All plasma samples were analyzed for concentrations of cortisol (radioimmunoassay kit #07221106, MP Biomedicals, Santa Ana, CA; Colombo et al, 2019 ) and haptoglobin ( Cooke and Arthington, 2013 ). Serum samples collected on d 0, d 13, d 27, d 41, and d 55 were analyzed for antibodies against bovine respiratory syncytial virus (#P00651-2; IDEXX Switzerland AG, Liebefeld-Bern, Switerland), bovine herpesvirus-1 (#99-41459; IDEXX), parainfluenza-3 virus (#P0652-2; IDEXX), bovine viral diarrhea viruses types I and II (#99-44000; IDEXX), and Mannheimia haemolytica (BIOK139 Monoscreen AbELISA; Bio-X Diagnostics S.A., Rochefort, Belgium).…”

Impacts of commingling on health and productive responses of beef heifers during feedlot receiving

“…All blood samples were placed immediately on ice, centrifuged (2,500 × g for 30 min; 4 °C) for plasma harvest and stored at −80 °C on the same day of collection. Plasma samples were analyzed for haptoglobin and cortisol as described by Colombo et al (2019) , with intra and interassay CVs ≤ 7%.…”

Administering an appeasing substance to beef calves at weaning to optimize welfare and productivity

“…Hair samples were collected from the tail-switch of all calves on days 0, 14, 28, and 42 and stored at −80 °C ( Schubach et al, 2017 ). Plasma samples were analyzed for haptoglobin and cortisol, and hair samples for cortisol as in Colombo et al (2019) . Across all assays, the intra and interassay coefficient of variation were ≤8.4%.…”