Combined approaches to reduce stress and improve livestock well-being: A review

Abstract

It is well established that various stressors confer hazardous impact on the welfare, health, productive, and reproductive efficiencies of farm animals. Among the major stress stimuli, temperature, transportation, weaning, pathogens, diet quality, and routine handling are cardinal in causing diminished performance of livestock. It is hypothesized that the key to reducing disease incidence and animal discomfort appears to be centered at reducing their response to stress. To this end, strategies that involve thermal conditioning at an early age, dietary interventions, and identification of genetic and biochemical biomarkers to predict the risk for developing stress-related diseases early, have been studied by our research team during the last two decades as means to alleviate stress in Aves and ruminants. The findings from these studies are presented here to illustrate how the applied strategies have contributed to the following outcomes: 1. In layer hens: Improved regulation of body temperature, reduced mortality rates, and a delayed onset of heat shock protein induction. 2. In cattle: a. mitigation of intestinal diseases and prevention of blood parasite invasion; b. identification of genomic and proteomic biomarkers predictive of susceptibility to bovine respiratory disease, the leading cause of morbidity and mortality among young cattle globally.

Keywords: BRD; Babesiosis; Biomarkers; Livestock; Stress.

Fig. 1

Simmental cows freely grazing on woodland pasture (a), or subjected to a controlled feeding experiment with fresh oak (Quercus calliprinos) leaves (b). Photos: Dr. Zalmen Henkin and Dr. Ariel Shabtay.

Fig. 2

Erythrocytes osmotic fragility* of Simmental cows (n = 24) freely ranging on grassland vs. woodland pastures. While the osmotic pressure (stress) required for 50% hemolysis (C₅₀; horizontal dashed line) of grassland grazing cows was 0.52 ± 0.03%NaCl, a more hypotonic stress (0.47 ± 0.04%NaCl) was needed to cause the same C₅₀ in woodland grazing cows (P = 0.004). The hemolytic values differed significantly between the linear areas (0.35%-0.6% NaCl) of the fragility curves of grassland (R² = 0.979) vs. woodland (R² = 0.993) cows. *based on Layton and Roper (2017).

Fig. 3

Fluorescence microscopy and FACS imaging demonstrating the capability of oak-derived polyphenols to bind to erythrocytes membranes. Fluorescence microscopy images of blood smears of control (a) and 5-week oak leaves-supplemented (b) Simmental cows. FACS imaging (c) exemplifying a rightward shift in erythrocytes fluorescence of oak leaves-fed cows (309, 903), in comparison to controls (602, 907, 104).

Fig. 4

A representative experiment showing the ability of norepinephrine (NE) to induce growth of Pasteurella multocida. Several strains of Pasteurella multocida were isolated, postmortem, from the lungs of BRD positive cattle. Microbes were freeze dried and sent for further analysis to Dr. Primrose Freestone at the University of Leicester, UK, for in vitro growth assay. The inoculum size of the Pasteurella multocida (Strain 05969) culture was 145 CFU/ml. Cultures were incubated (in triplicate) in bovine serum/SAPI medium for 24 h. NE was used at 50 μM. When added to the medium, NE induced a significant (P = 3.72E-06) growth (9.83E+06±472582) of Strain 05969 comparing to control (1.25E+05±4726). Another experiment, on strain 07809, using inoculum size 100 CFU/ml, showed a similar tendency (data not shown).

Fig. 5

Protein-protein association network highlighting the glycolysis and gluconeogenesis metabolic pathways, highly expressed (P = 5.98e-10) in oral fluid of 1–7 days old calves, positively-diagnosed for BRD at the age of three months. The following proteins, PGK1, ALDOA, GAPDH, PKM2, LDHB, PGM2, PGAM1, LDHA, and ENO1, comprising these networks, were expressed x17, x14, x12, x10, x4.8, x4, x3.5, x2.3, x2 higher than in their counterparts.

Fig. 6

Flowchart depicting three typical stress scenarios (heat stress, pathogens, and transportation) discussed in this manuscript that livestock commonly encounter. For each stressor and organism (laying hens and cattle), associated consequences, mitigation approaches, and resulting outcomes are presented. The Figure was created in BioRender software. Photographs were taken by Dr. Zalmen Henkin and Dr. Ariel Shabtay.