EFFECT OF FORAGE INCLUSION STRATEGY IN FINISHING BEEF CATTLE AND THE IMPACT ON GROWTH PERFORMANCE, RUMEN FERMENTATION AND MICROBIOTA, BLOOD SERUM PARAMETERS, CARCASS CHARACTERISTICS, AND LIVER ABSCESSES
Date
2024-07-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
Liver abscesses can have a negative impact on economic return in finishing cattle and recent audits have reported incidence in 30.8 – 31.5% of livers at slaughter. A study was conducted to evaluate different strategies of forage inclusion in finishing beef cattle diets and its impact on feed intake, ruminal fermentation and microbiota, blood serum parameters, growth performance, carcass quality, and liver abscesses. Steers (n = 360, 400 ± 29kg) were stratified by weight and randomly allocated across 24 pens, which were randomly assigned to 1 of 4 dietary treatments (15 steers per pen, 6 pens per treatment) in a completely randomized experiment. Treatments included: 1) positive control (+CTRL) fed a diet (7.5% forage on a diet DM basis) with tylosin (11 mg/kg); 2) negative control (-CTRL; control diet without tylosin); 3) a diet where forage concentrations decreased (DECR) every 42 days and was static for the last 84 days (forage comprised 15%, 9%, 3% and 3% of diet DM, respectively) without tylosin; and 4) a diet where forage concentration increased (INCR), the inverse of the DECR, without tylosin. The +CTRL steers had greater ADG (1.74 kg/d vs. 1.63 kg/d, P = 0.05), shrunk total BW gain (306 vs. 287, P = 0.05), and a tendency for greater final BW (705 vs. 687, P = 0.07) than INCR steers. A diet × period interaction was observed for DMI (P < 0.01), but it did not differ among treatments (P > 0.10) over the full study. Yield scores and rib fat thickness were greater in -CTRL than INCR steers (1.69 mm vs. 14.2 mm; P = 0.04) and the percentage of steers with minor liver abscesses tended (P = 0.055) to be less for +CTRL (51.8%) and DECR (51.8%) compared to –CTRL (62.2%) and INCR (64.3%). Implementing greater dietary concentrations of forage early in finishing, with a subsequent decline thereafter, has the potential to decrease the proportion of minor liver abscesses may occur, in a manner similar to that of typical finishing diets with tylosin, without impacting growth performance or carcass quality.
Description
Keywords
beef cattle, feedlot, forage inclusion, liver abscess
Citation
Degree
Master of Science (M.Sc.)
Department
Animal and Poultry Science
Program
Animal Science