Effect of Dietary Rumen-Protected L-Tryptophan Supplementation on Growth Performance, Blood Hematological and Biochemical Profiles, and Gene Expression in Korean Native Steers under Cold Environment.

Jae-Sung Lee,Jun-Ok Moon,Dong-Qiao Peng,Jalil Ghassemi Nejad,Wahyu Priatno,Jin-Seung Park,Hong-Gu Lee

doi:10.3390/ani9121036

Jae-Sung Lee, Jun-Ok Moon + Show 5 more

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https://doi.org/10.3390/ani9121036

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Abstract

Simple SummaryIn this study, the effect of dietary rumen-protected L-tryptophan (RPT) supplement on growth performance, blood hematological and biochemical profiles, and gene expression was investigated in beef steers during a cold environment. We revealed that supplementation of 0.1% RPT incorporated into diet was beneficial owing to enhanced growth performance by increasing the ADG and glucose level, decreasing the feed conversion ratio, and maintaining homeostasis in immune responses in beef steers in a cold environment.We assessed the growth performance, physiological traits, and gene expressions in steers fed with dietary rumen-protected L-tryptophan (RPT) under a cold environment. Eight Korean native steers were assigned to two dietary groups, no RPT (Control) and RPT (0.1% RPT supplementation on a dry matter basis) for six weeks. Maximum and minimum temperatures throughout the experiment were 6.7 °C and −7.0 °C, respectively. Supplementation of 0.1% RPT to a total mixed ration did not increase body weight but had positive effects of elevating average daily gain (ADG) and reducing the feed conversion ratio (FCR) on days 27 and 48. The metabolic parameter showed a higher glucose level (on day 27) in the 0.1% RPT group compared to the control group. Real-time PCR analysis showed no significant differences in the expression of muscle (MYF6, MyoD, and Desmin) metabolism genes between the two groups, whereas the expression of fat (PPARγ, C/EBPα, and FABP4) metabolism genes was lower in the 0.1% RPT group than in the control group. Thus, we demonstrate that long-term (six weeks) dietary supplementation of 0.1% RPT was beneficial owing to enhanced growth performance by increasing the ADG and glucose level, decreasing FCR, and maintaining homeostasis in immune responses in beef steers in a cold environment.

Highlights

The climate in the Korean peninsula is becoming more polarized owing to the global climate change resulting in longer, colder winters and longer, hotter summers [1,2]
We investigated performance parameters of average daily gain (ADG), feed conversion ratio (FCR), and feed intake of steers supplemented with total mixed ration (TMR) containing 0.1% rumen-protected L-tryptophan (RPT) during a cold environment
Animals in the RPT group showed higher (p = 0.001) ADG and lower (p = 0.001) FCR compared with the control group during the final day of the experiment

Summary

Introduction

The climate in the Korean peninsula is becoming more polarized owing to the global climate change resulting in longer, colder winters and longer, hotter summers [1,2]. Given this inevitable phenomenon, the decline in productivity of ruminants resulting in serious economic effects due to low temperature in winter is expected to accelerate [3,4]. Cold stress causes negative effects on growth performance and immune cell population by influencing metabolic and immunological activities [5,6]. Adaptation to cold environments in ruminants involves increasing thermal insulation, appetite, and basal metabolic intensity that improve cold hardiness and reduce the risks of both acute and chronic cold stress [5,6,10]

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