Dietary effects of protected fat, glycerol, and soybean meal on performance, physiological parameters, carcass characteristics, and behavioral measurements of late-fattening Hanwoo steers under heat stress conditions

Woo, Jun Sik; Ryu, Gyeong Rim; Kim, Jeong Hoon; Jang, Sun Sik; Lee, Hong Gu; Park, Keun-kyu

doi:.0.0.0

Article

https://doi.org/10.5713/ab.23.0503 [Accepted] Published online April 25, 2024.

Dietary effects of protected fat, glycerol, and soybean meal on performance, physiological parameters, carcass characteristics, and behavioral measurements of late-fattening Hanwoo steers under heat stress conditions

Jun Sik Woo¹

¹Department of Animal Science and Technology, Konkuk University, Seoul 05029, Korea
²National Institute of Animal Science, Rural Development Administration, Cheonan 31000, Korea
³Cargill Agri Purina Inc., Seongnam 13630, Korea
⁴National Institute of Animal Science, Rural Development Administration, Pyeongchang 25340, Korea

Correspondence: Keun-kyu Park, Tel: +82-2-450-3661, Fax: +82-2-455-1044, Email: kkpark@konkuk.ac.kr

Received: 26 November 2023 • Revised: 3 January 2024 • Accepted: 18 February 2024

Abstract

Objective
This study aimed to determine the effects of increasing energy and protein levels in diets by including protected fat (PF), glycerol (GL), and soybean meal (SBM) on growth performance, physiological parameters, carcass characteristics, and behavioral measurements of late-fattening Hanwoo steers under heat stress conditions.
Methods
Thirty-six steers (initial BW, 724.9 ± 58.3 kg; age, 25.5 ± 0.4 month) were assigned into Control (TDN 76%, CP 15%), PF (TDN 83.6%, CP 15%), PF+GL (TDN 83.6%, CP 15%) and PF+GL+SBM (TDN 83.6%, CP 16.5%) by randomized complete block design for a total of 16 weeks with division of 4 week periods. The average temperature-humidity index was 87.0 (1st period; Severe), 82.8 (2nd; Moderate), 71.4 (3rd; Comfort), and 68.1 (4th; Comfort).
Results
The DMI showed no treatments differences during the whole experiment. However, DMI in 1st and 2nd period decreased by approximately 30% and 10% compared to 4th period, respectively. Higher ADG and FCR were noted for treatments compared to Control at both 1st and 2nd period (p<0.05). There were no treatment effects on rectal temperature (RT), cortisol, and behaviors during the entire experiment. However, both RT and cortisol in 0, 1st and 2nd period were higher than those of 3rd and 4th period (p<0.05). Carcass yield and grade remained unaffected by increasing TDN and CP levels. Behavioral changes in the hot season (1st period) included reduced lying (43%), increased standing (48%), decreased walking (62%), and decreased eating (38%) (p<0.05), with an increase in drinking by 54%. Rumination during standing was 53% higher, while rumination during lying was about 33% lower compared to the post-hot season (3rd period) (p<0.05).
Conclusion
Dietary supplementation of protected fat in late-fattening Hanwoo steers under heat stress had a positive effect on preventing a reduction in performance.

Keywords: Heat Stress; Protected Fat; Glycerol; Soybean Meal; Hanwoo Steers; Late-fattening Period