Effects of different protein levels on growth performance and stress parameters in beef calves under heat stress

Abstract

This study investigated the effects of dietary protein levels under various heat stress (HS) conditions on the growth performance and stress parameters in Korean native beef calves. Male calves (n = 40; initial BW = 202.2 ± 3.31 kg) were randomly assigned to climatic-controlled chambers with 3 × 3 factorial arrangements. Calves were assigned into three dietary protein levels (low protein; LP = 12.5%, medium protein; MP = 15%, and high protein; HP = 17.5%) and three HS levels [mild: temperature-humidity index (THI) = 74 to 76, moderate: THI = 81 to 83, and severe: THI = 89 to 91] with control (threshold: THI = 70 to 73 and dietary protein level 12.5%). The calves were subjected to ambient temperature (22 °C) for 7 days and subsequently to the temperature and humidity corresponding to the target THI level for 21 days. The data were analyzed using the repeated-measures analysis by the GLM procedure of SAS. As a result, average daily gain (ADG) was decreased (P < 0.05) under severe HS level compared to the mild and moderate HS stress levels. However, HP increased ADG (P < 0.05) than moderate levels (LP) and severe levels (LP and MP). Under different HS levels (mild, moderate, and severe), HR, RT, and blood cortisol were increased (P < 0.05) compared to a threshold level, but no differences were observed in the parameters among various protein levels. Varied HS levels decreased the levels of blood glucose, NEFA, and amino acids (AAs) (lysine and glutamic acid) compared to a threshold (P < 0.05). But, the HP group resulted in increased (P < 0.05) levels of blood glucose, NEFA, and AAs (lysine and glutamic acid) compared to LP and MP groups under severe HS stress. The expression level of the HSP70 gene in peripheral blood mononuclear cell (PBMC) and hair follicles was increased (P < 0.05) following an increase in moderate and severe HS levels. Also, HSP70 gene expression in the HP group was decreased (P < 0.05) compared with LP and MP groups under intense HS level. Overall, HS in Korean native beef calves exhibited negative effects on ADG, blood glucose, NEFA, and AA profile. However, 17.5% of dietary protein (HP) could compensate for the growth of heat-exposed Korean native beef calves through the regulation of homeostasis by protein and energy metabolism. Also, it was evident that adequate protein (HP) is used as a major nutrient for HSP70 synthesis in PBMC and hair follicles causing, a boost in the immune system of heat-exposed Korean native beef calves.

Influence of feeding mustard oil cake and soybean meal in calf starter on growth and blood metabolites of crossbred dairy calves

“…The control diet's lower protein content might be responsible for minimal body weight gain. Accordingly, the observed effect is supported by Kim et al (2022), who claimed that calves offered starter feed with 17.5% CP showed higher weight gain compared to the less-protein diet with 12.5% or 15% CP. In addition, the control diet had a minimum RUP content where soybean meal and mustard oil cakes were excellent sources of RUP (Prusty et al 2013).…”

Impact of Cold Stress on Physiological, Endocrinological, Immunological, Metabolic, and Behavioral Changes of Beef Cattle at Different Stages of Growth

“…Previous research found that animals exposed to acute CS for the first time without acclimation had an increased HR and RT, which is consistent with the stress response in this study [ 27 , 28 ]. The HR and RT can be used as indicators of thermal balance in the body to assess the adverse effects of environmental stress on growth performance and productivity [ 12 , 14 , 29 ]. The cortisol levels in the blood are associated with abnormal animal behaviors such as anxiety and sensitivity [ 30 ].…”

Heat Stress Effects on Physiological and Blood Parameters, and Behavior in Early Fattening Stage of Beef Steers

“…Regarding this, average ambient temperatures have continuously increased during the summer season due to global warming, further aggravating damage to livestock [ 1 , 7 ]. HS causes behavioral and metabolic changes in cattle that result in lower productivity and profitability [ 3 , 5 ]. Many previous studies have demonstrated that the physiological responses of cows in the body, such as intake, heart rate, and rectal temperature, change to maintain homeostasis after exposure to HS [ 19 , 20 ].…”

“…Heat stress can create multiple issues for cattle, such as increased metabolic disorders and decreased growth performance, immune function, and lactation [ 2 , 3 ]. Heat stress in beef cattle reduces nutrient intake, body weight (BW) gain, and meat quality, all of which can potentially cause large economic losses [ 4 , 5 , 6 ]. It is estimated that HS causes approximately USD 370 million in losses for the beef cattle industry [ 7 ].…”

“…In our previous studies [ 3 , 4 , 5 , 11 , 12 ], we combined not only physiological indicators but also blood metabolites, heat shock protein (HSP) 70, behavior parameters, etc., to determine HS levels in beef calves. Blood metabolites, such as glucose and blood urea nitrogen (BUN) levels, changed during HS due to reduced DMI [ 3 ].…”