mild heat
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2021 ◽  
Vol 5 (Supplement_S1) ◽  
pp. S61-S66
Author(s):  
Morgan R Stegemiller ◽  
Melinda J Ellison ◽  
John B Hall ◽  
James E Sprinkle ◽  
Brenda M Murdoch

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 281-281
Author(s):  
Morgan R Stegemiller ◽  
Melinda J Ellison ◽  
John B Hall ◽  
James E Sprinkle ◽  
Brenda M Murdoch

Abstract Rangeland is a valuable resource that can allow producers to cost effectively provide nutrients for grazing cattle. However, grazing behavior of cattle is adversely affected when the temperature humidity index is greater than 72. It is possible to select cattle that exhibit efficient grazing behavior even under mild heat stress. This study evaluated genetic associations with grazing behavior to help producers identify cows that will effectively use their rangeland pastures. Using genome-wide associations, this study identified single nucleotide polymorphisms (SNPs) associated with grazing time, walking time and max slope that cattle utilized while experiencing mild heat load. Data were collected from Angus X Hereford 2-year-old beef cows from UI herd over two years (37 grazing and walking minutes, 38 max slope). Genotypes were obtained using a Bovine GGP 50K SNP marker array and 41,686 markers were used in the analyses. Two SNPs on chromosome 11 are significantly (P = 5.01e-7, P = 6.46e-7) associated with grazing minutes and explain 0.52 proportion of variance (PVE). A SNP on chromosome 3 is significant for walking minutes (P=1.91e-6) with a PVE of 0.48. Additionally, a SNP on chromosome 14 is significantly (P = 8.50e-6) associated with max slope and has a PVE of 0.43. This ongoing project identified significant associations with grazing and walking minutes and maximum slope. This research will be strengthened with the addition of more animals over successive years. Some cattle spend more time grazing, walking, or at a higher elevation in mild heat load. Identifying genetic variants associated with grazing time, walking time, and maximum slope use while under heat stress can enable producers to select for cattle that best fit the rangeland available to them.


Author(s):  
Jiemeng Xu ◽  
Stuart Jansma ◽  
Mieke Wolters-Arts ◽  
Peter de Groot ◽  
Ivo Rieu

Crop reproductive success is significantly challenged by heatwaves, which are increasing in frequency and severity globally. A major reason is reduced male fertility due to deviations in pollen development, but the mechanism behind this is not well understood. Here, long-term mild heat (LTMH) treatment, mimicking a heatwave, was applied locally to flowers or to whole plants and followed up by cytological, transcriptomic and biochemical analyses. LTMH was shown to act directly on the flowers and not via a systemic effect on other plant tissue. The meiosis to early microspore stage was the most sensitive to LTMH and three days of exposure around this period was sufficient to significantly reduce pollen viability. Extensive cytological analysis showed that abnormalities in pollen development could first be observed after pollen mitosis I, while tapetum development appeared unaffected. Transcriptomic and biochemical analyses suggested that pollen development suffered from tapetal ER stress and that there was a limited role for oxidative stress. These characteristics differentiate the response of developing anthers and pollen to LTMH from the response to severe heat stress.


Food Control ◽  
2021 ◽  
pp. 108577
Author(s):  
Lin Chen ◽  
Qin Liu ◽  
Xue Zhao ◽  
Hongfei Zhang ◽  
Xinyi Pang ◽  
...  

2021 ◽  
Vol 12 ◽  
Author(s):  
Vivek A. Kuttappan ◽  
Megharaja Manangi ◽  
Matthew Bekker ◽  
Juxing Chen ◽  
Mercedes Vazquez-Anon

Wooden breast (WB) is a degenerative myopathy seen in modern broiler birds resulting in quality downgrade of breast fillets. Affected filets show increased toughness both before as well as after cooking and have decreased water holding capacity and marinade pick up compared to normal fillets. Although the exact etiology is unknown, the circulatory insufficiency and increased oxidative stress in the breast muscles of modern broiler birds could be resulting in damage and degeneration of muscle fibers leading to myopathies. Three independent experiments were conducted to evaluate the effect of various dietary interventions on the incidence of WB when birds are exposed to oxidative stress associated with feeding oxidized fat and mild heat stress. Feed additives such as dietary antioxidant [Ethoxyquin (ETX)], mineral methionine hydroxy analog chelate (MMHAC) of Zn, Cu, and Mn, and organic selenium (Org Se) were tested at recommended levels. In experiment 1, ETX reduced (P < 0.05) the incidence of severe WB induced by oxidized fat diet. The magnitude of improvement in percentage of normal (no WB) filets and reduction in muscle lipid peroxidation was greater (P < 0.05) when ETX and MMHAC were fed together as shown by experiment 2. In birds exposed to mild heat stress (Experiment 3), feeding MMHAC by itself reduced (P < 0.05) tissue damage by reducing incidence of tibial head lesions, skin scratches, breast blisters, in addition to increasing the incidence of normal (no WB) fillets. When MMHAC was combined with ETX and Org Se, further improvement (P < 0.05) in normal (no WB) filets was observed. In summary, under different oxidative stress conditions, dietary intervention programs that contain ETX, MMHA-Zn, -Cu, and -Mn and Org Se can improve performance and increase carcass integrity, reducing problems, such as WB, either independently or with additive effect. This effect is most likely attained by simultaneously improving the exogenous and endogenous antioxidant status, reducing oxidative stress, and improving tissue healing process of the bird.


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