scholarly journals Biological responses of feedlot cattle to heat load

2016 ◽  
Author(s):  
Angela Lees
Keyword(s):  
Heat Load ◽  
Feedlot Cattle ◽  
Biological Responses

Feeding strategies for managing heat load in feedlot cattle

2002 ◽  
Vol 80 (9) ◽  
pp. 2373 ◽  
Author(s):  
T. L. Mader ◽  
S. M. Holt ◽  
G. L. Hahn ◽  
M. S. Davis ◽  
D. E. Spiers
Keyword(s):  
Heat Load ◽  
Feedlot Cattle ◽  
Feeding Strategies

scholarly journals Metabolism and Endocrinology of Cattle in High Environmental Temperatures

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 211
Author(s):  
Gene Wijffels ◽  
Megan Sullivan ◽  
Stephen Anderson ◽  
Sally Stockwell ◽  
Suzie Briscoe ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Respiration Rate ◽  
Heat Load ◽  
Recovery Period ◽  
Plasma Concentrations ◽  
High Heat ◽  
Feedlot Cattle ◽  
Chloride Ions ◽  
Rumen Temperature ◽  
High Heat Load

Close-to-market weight grain fed cattle experience high heat loads during summer. There are health, welfare and production impacts on these high value animals. Two cohorts of 600 kg Black Angus steers (n = 12) were subjected to heatwave conditions during a thermal challenge in climate chambers. Frequent blood sampling enabled a detailed description of the metabolic and endocrine trajectories during high heat load and recovery in feedlot cattle. In high heat load ruminants, blood flow is diverted from the major organs impacting metabolic rate and cellular functions. The metabolic rate will slow with falls in the thyroid hormone plasma concentrations. Insulin and the adipokines gave an indifferent response. The high heat load cattle were hypoglycaemic and oxidising fatty acids. Liver involvement was evidenced by the build-up of bilirubin in plasma, and reduced release of cholesterol and ALP. Thermal challenge saw markedly increased plasma creatinine and urea implicating reduced glomerular filtration; although the kidneys were working to retain chloride ions to balance the loss of bicarbonate from the increased respiration rate. As heat load reduced during recovery, rumen temperature and respiration rate normalised and feed intake gradually returned. Plasma glucose levels increased also. With increased blood supply to the organs, there was a rise in liver enzymes into the blood, although liver function had not fully restored during the recovery period; plasma bilirubin concentrations were still high, and ALP and cholesterol levels low. Twelve days after the thermal challenge, most blood parameters had returned to normal and the steers had gained weight.

Influence of shade on panting score and behavioural responses of Bos taurus and Bos indicus feedlot cattle to heat load

2020 ◽  
Vol 60 (2) ◽  
pp. 305 ◽  
Author(s):  
A. M. Lees ◽  
J. C. Lees ◽  
V. Sejian ◽  
M. L. Sullivan ◽  
J. B. Gaughan
Keyword(s):  
Treatment Group ◽  
Observational Data ◽  
Heat Load ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Observation Time ◽  
Feedlot Cattle ◽  
Night Time ◽  
Treatment Groups ◽  
Panting Score

Context Feedlot cattle can be negatively impacted by hot conditions, such that they have reduced performance and wellbeing. This study was conducted at the research feedlot located at The University of Queensland during a southern hemisphere summer (October to April). Aims The objective of this study was to evaluate the influence of shade on the behaviour and panting score of Bos taurus and Bos indicus feedlot cattle during summer. Methods Thirty-six steers (12 Angus, 12 Charolais and 12 Brahman) with an initial non-fasted liveweight of 318.5 ± 6.7 kg were used in a 154-day feedlot study consisting of two treatments: unshaded and shaded (3 m2/animal). Observational data were obtained for each steer at 2 h intervals between 0600 and 1800 hours daily from Day 1 to Day 154. Additional night time observational data were collected at 2-h intervals between 2000 and 0400 hours on 12 occasions. Data collected included activity (feeding, drinking, or ruminating), posture (standing or lying) and panting score. Panting scores were used to calculate a mean panting score for each breed × treatment group. Observational data were converted to a count for each breed × treatment group for each observation time point and were analysed using a binomial generalised linear model. Key results Maximum shade utilisation was the greatest at 1200 hours for Angus (85.5%), Charolais (32.7%) and Brahman (33.3%) steers. All breed × treatment groups exhibited a notable increase in mean panting score as heat load increased. Average increase in mean panting score was 0.36, where shaded Brahman exhibited the smallest increase (0.13) and unshaded Angus had the greatest increase (0.71). When heat load conditions were very hot (heat load index (HLI) ≥ 86) the mean panting score of all breed × treatment groups differed (P < 0.05). Conclusions Overall these results emphasise the importance of providing shade to feedlot cattle, irrespective of genotype. Implications These results further highlight the importance of providing shade to feedlot cattle. These results challenge the general perception that Bos indicus feedlot cattle do not require access to heat load alleviation strategies.

Strategies to Reduce High Heat Load on Feedlot Cattle

2013 ◽  
Author(s):  
J.B. Gaughan ◽  
T.M. Kunde ◽  
T.L. Mader ◽  
S.M. Holt ◽  
A. Lisle ◽  
...  
Keyword(s):  
Heat Load ◽  
High Heat ◽  
Feedlot Cattle ◽  
High Heat Load

Heat Load Management for Feedlot Cattle

2013 ◽  
Author(s):  
T. L. Mader ◽  
S. M. Holt ◽  
J. B. Gaughan ◽  
G. L. Hahn ◽  
M. S. Davis ◽  
...  
Keyword(s):  
Heat Load ◽  
Feedlot Cattle ◽  
Load Management

Heat stress in cattle and the effect of shade on production and behaviour: a review

1994 ◽  
Vol 34 (2) ◽  
pp. 285 ◽  
Author(s):  
JK Blackshaw ◽  
AW Blackshaw
Keyword(s):  
Heat Stress ◽  
High Temperatures ◽  
Heat Load ◽  
Heat Dissipation ◽  
Bos Taurus ◽  
Heat Stroke ◽  
Bos Indicus ◽  
Feedlot Cattle ◽  
Sweat Glands ◽  
Principal Mechanism

At high temperatures, evaporative cooling is the principal mechanism for heat dissipation in cattle. It is influenced by humidity and wind speed and by physiological factors such as respiration rate, and density and activity of sweat glands. Following exposure to heat, cattle appear to acclimatise within 2-7 weeks. The failure of homeostasis at high temperatures may lead to reduced productivity or even death. Knowledge of characteristic behavioural signs of increasing heat stress may alert cattle handlers to impending heat distress, particularly in areas of potential climatic extremes of high temperatures and humidities. Reduction of the heat increment of feeding by dietary manipulation may partially protect cattle from forecast heat stress. Under high heat stress, Bos indicus breeds and their crosses have better heat regulatory capacities than Bos taurus breeds, due to differences in metabolic rate, food and water consumption, sweating rate, and coat characteristics and colour. Also, because Bos taurus have a higher heat loading at the skin, they must evaporate substantially more sweat than Bos indicus to maintain normal body temperatures. Welfare concerns exist about heat stress and the provision of shade for feedlot cattle. In hot weather, cattle actively seek shade, which may reduce the radiant heat load by 30% or more. Under conditions of extreme heat load, shading may maintain production and reduce deaths from heat stroke. Shading of feed and water also offers production advantages for British and European breeds of cattle.

Is the link between emotional suppression and biological responses to stress mediated by rumination?

2010 ◽  
Author(s):  
Charlotte Leonie Stewart ◽  
Jolanta Opacka-Juffry ◽  
Changiz Mohiyeddini
Keyword(s):  
Emotional Suppression ◽  
Biological Responses
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