Stress In Beef Cattle Research Articles

Heat Stress in Beef Cattle: Climate Change and the Global Scenario – A Review

Abstract With the increasing human population and urbanization, the demand for animal origin products is going to grow, especially in the developing nations till the 2050s and the production needs to be escalated and optimized with the changing climate. Heat stress is known to reduce the animal performance, production, shelf life and meat quality in all animals. The beef cattle are globally reared, following different managemental practices, so the usage of natural resources like land and water, manpower, fodders, production systems and the environmental impact also varies profoundly. Recent changes in the climate, global warming and depletion of resources have severely affected the production and heat stress is now a common constraint all over the world. Due to evolutionary diversification the tropical and temperate breeds are comparatively more thermotolerant, but the beef cattle in the colder regions are vulnerable to high environmental temperatures. Also, the production of beef increases the carbon footprint and is much less eco-friendly than growing plant-based protein. So, we comprehended the environmental temperature variation over the continents and impact of heat stress on beef cattle. Also, other factors like cattle population, land and pasture usage, livestock units in trade, methane emissions and gross beef production value were examined to evaluate the collective impact of all these on the beef sector. Our findings and predictions reveal that, in the advent of climate change, depleting natural resources and rise in the greenhouse gases, beef production will be a constant challenge, which can be only achieved by maintaining a healthy cattle population and optimum usage of natural resources. Only then can the beef sector be efficient, sustainable, and a profitable enterprise in future.

PSII-5 Effect of short-term feeding of hemp (Cannabis sativa) on stress biomarkers in weaned beef calves

Abstract Hemp research is growing rapidly due to its health benefits for animals; however, there is little information on its effects on stress. The objective of this study was to determine the effects of hemp supplementation on stress biomarkers in beef calves during weaning. Calves (n = 12) were completely randomized into Control (CC: received commercial concentrates before and after weaning), Treatment 1 (CH: received commercial concentrates before weaning and 25 g of hemp diet after weaning), Treatment 2 (HC: received 25 g hemp diet before weaning and commercial concentrates after weaning) and Treatment 3 (HH: received 25 g hemp diet before and after weaning). The study lasted for 28 d; blood samples were collected at 7-d intervals for enzyme-linked immunosorbent assay. Plasma was analyzed for heat shock protein 90, cortisol, haptoglobin, total antioxidant capacity, and glutathione peroxidase. There was treatment x time interaction in cortisol concentrations, with the (CH) group showing the greatest concentration of cortisol (124.23 ng/mL) in wk 3. There was no significant (P = 0.0675) difference in total antioxidant capacity. There was a treatment x time interaction (P = 0.0009) in glutathione peroxidase concentrations, with the (HH) group showing the greatest concentration of glutathione peroxidase of 46.83 ng/mL in wk 2 and 47.57ng/mL in wk 3. There was no significant (P < 0.05) difference in heat shock protein and haptoglobin. We concluded that hemp supplementation could reduce weaning stress in beef cattle, thereby improving the productivity and performance of beef calves

Metabolic profile of Charolais young bulls transported over long-distance

Long-distance transport can cause stress to beef cattle impairing health and growth performances. This study aimed to deepen the knowledge of the effects of long-distance transport on young bulls’ metabolic profile to identify reliable blood parameters for monitoring their health and welfare. Eighty Charolais young bulls, transported for 12 hours to the final fattening unit, were weighed and blood sampled at three time intervals: before leaving the commingling centre (day −1), upon arrival at the fattening unit (day 0), and 7 days post-arrival (day 7). These bulls were part of a larger study aimed at testing whether the animals have some benefit from the supplementation of live yeast and selenium through slow-release rumen boluses that were administered to half of them before departure from France (‘Yeast’ vs ‘Control’ group). The effect of the supplementation on the parameters considered in this study was included in the statistical analysis to account for the structure of the experimental design. Transport affected the initial body weight of the animals, which dropped on day 0 and it was not fully recovered on day 7. Most plasma traits of protein, energy, hepato-muscle, and mineral profiles were affected by transport. Cortisol was also assessed and peaked at day 0. The footprint of the long-distance transport on bulls’ metabolic profile indicated a combination of stress, energy deficit, and muscle damage, with a certain degree of dehydration and liver impairment. Plasma traits measured on day −1 highlighted that stressful conditions and physiological responses of the bulls to recover homeostasis already started during the commingling phase before departure. No effect of supplementation was detected, except for higher selenium plasma level in Yeast bulls at day 7. Among blood parameters, non-esterified fatty acids, total protein, cortisol, glucose, and iron were those responsible for most of the variation in metabolic profile of bulls undergoing long journey. Therefore, these traits might be used as major biomarkers to assess stress in transported beef cattle, helping to identify critical situations for which proper mitigating actions should be taken. The outcomes of this study suggested that preventive measures against transport stress in beef cattle should start at the commingling of the animals in the collection centers, thus before departure.

The Effect of the PhoP/PhoQ System on the Regulation of Multi-Stress Adaptation Induced by Acid Stress in Salmonella Typhimurium.

Acidic stress in beef cattle slaughtering abattoirs can induce the acid adaptation response of in-plant contaminated Salmonella. This may further lead to multiple resistance responses threatening public health. Therefore, the acid, heat, osmotic and antibiotic resistances of Salmonella typhimurium (ATCC14028) were evaluated after a 90 min adaption in a pH = 5.4 "mild acid" Luria-Bertani medium. Differences in such resistances were also determined between the ∆phoP mutant and wild-type Salmonella strains to confirm the contribution of the PhoP/PhoQ system. The transcriptomic differences between the acid-adapted and ∆phoP strain were compared to explore the role of the PhoP/Q two-component system in regulating multi-stress resistance. Acid adaptation was found to increase the viability of Salmonella to lethal acid, heat and hyperosmotic treatments. In particular, acid adaptation significantly increased the resistance of Salmonella typhimurium to Polymyxin B, and such resistance can last for 21 days when the adapted strain was stored in meat extract medium at 4 °C. Transcriptomics analysis revealed 178 up-regulated and 274 down-regulated genes in the ∆phoP strain. The Salmonella infection, cationic antimicrobial peptide (CAMP) resistance, quorum sensing and two-component system pathways were down-regulated, while the bacterial tricarboxylic acid cycle pathways were up-regulated. Transcriptomics and RT-qPCR analyses revealed that the deletion of the phoP gene resulted in the down-regulation of the expression of genes related to lipid A modification and efflux pumps. These changes in the gene expression result in the change in net negative charge and the mobility of the cell membrane, resulting in enhanced CAMP resistance. The confirmation of multiple stress resistance under acid adaptation and the transcriptomic study in the current study may provide valuable information for the control of multiple stress resistance and meat safety.

The physiology of heat stress in beef cattle

The physiology of heat stress in beef cattle

5 Effects of Virtual Fencing on Cortisol Concentrations and Behavior of Beef Cattle

Abstract Two experiments were conducted to evaluate the effects of virtual fencing on stress in beef cattle. In both experiments, cattle were contained by either physical, 2-strand electric fencing or by use of a proprietary, GPS-based virtual fencing collar, with no physical interior fencing. In both studies, hair from the tail switch was collected at the end of the experiment, and analyzed for cortisol concentration to measure the accumulated stress experienced by the cattle. Additionally, a subset of cattle were fitted with pedometers to measure behavior responses. In the initial pilot experiment, 55 heifers were grazed for 28 d in either 1 physically-fenced pasture or 1 virtually-fenced pasture. In the second experiment, 59 mature cows and heifers were grazed for 56 d in 1 of 2 physically-fenced or 1 of 2 virtually-fenced pastures (4 pastures total). In the second experiment, blood samples were also collected and NEFA and lactate were quantified in plasma. Only descriptive statistics were summarized for the pilot experiment, which indicated that hair cortisol concentrations were within published ranges for both fence types (0.39 ± 0.32 and 0.37 ± 0.15 pg/mg for physically- or virtually-fenced animals, respectively), and step count and motion index appeared elevated in the first few days of adaptation to virtual fence. The second experiment was analyzed with analysis of variance as a completely random design with pasture as the experimental unit. No effect of fence type was found for behavior (number of steps, standing time, lying bouts, or motion index; P > 0.16). Further, no difference was observed in cortisol, lactate nor NEFA (P > 0.14) concentrations due to fence type. None of this data suggests that virtual fencing is different from physical fencing in the effects on cattle stress and behavior, indicating further research and development of virtual fencing technology are warranted.

Small RNA-Seq Analysis Reveals miRNA Expression of Short Distance Transportation Stress in Beef Cattle Blood.

Simple SummaryIn this study, three miRNA modules were identified in a cattle short-distance transportation stress model, and the turquoise module showed key miRNA sets according to their correlation with hub genes. Further, hub miRNAs were identified based on their targeting relationship with hub genes in our previous study. This finding provides the potential utility for predicting and treatment of short-distance transportation stress in beef cattle.Transportation is a crucial phase in the beef cattle industry, and the annual losses caused by beef cattle transport stress are substantial. Because of its huge economic losses, such as lower growth rate and even death, long-distance transportation stress has attracted more attention from beef production practitioners because of its huge economic losses. Compared with the long-distance transportation stress, the short-distance transportation stress was ignored for the reason of no obvious symptoms in cattle. Our previous study showed that the disorder of B cell function could be a potential health risk after short-distance transportation. However, the transcriptome details of the changes in the cattle blood after short-distance transportation and the molecular mechanisms for the regulation of the developmental process are not clearly known. In this study, a total of 10 Qinchuan cattle were used to compare the molecular characteristics of blood before and after short-distance transportation. The miRNA-seq showed that 114 differentially expressed miRNAs (DEMs) were found (40 upregulated and 74 downregulated) between two groups before and after transportation. Furthermore, more than 90% of the miRNAs with counts of more than 10 were used to construct a co-expression network by weighted correlation network analysis (WGCNA), and four independent modules were identified. According to their relationship with 30 hub genes, the turquoise module was the key module in this study. The regulator network of hub genes and miRNAs in the turquoise module was constructed by miRNAs targeting genes predicting, and the miRNAs had targeting sites within hub genes that could be identified as hub-miRNAs. Further, it showed that CD40 and ITPKB had the same targeting miRNAs (miR-339a/b), and the newly discovered hub miRNAs filled the gaps in our previous study about the relationship between hub genes in short-distance transportation stress and provided the potential utility for predicting and treatment of short-distance transportation stress in beef cattle.

Heat stress mitigation strategies for beef cattle under intensive finishing in the Mexican dry tropics

Objective: Review the heat stress mitigation strategies in intensive cattle feedlots in the tropical region of México.Approach: Beef cattle production is one of the principal activities of the agricultural sector; therefore, to maintain the inventory in intensive finishing pens, a considerable number of cattle are moved to geographic areas where climatic conditions are not always favorable for most of the year. High environmental temperature combined with relative humidity create heat stress conditions andconsequently affecting the productive indicators by compromising the physiologicalstability of the cattle.Implications: The improvement of housing conditions to mitigate the effects of heat stress in beef cattle in intensive finishing involves considering living space, available shade area, feeding and watering space that assure the cattle welfare during their stay in livestock production units. Conclusions: Heat stress mitigation strategies in beef cattle during intensive finishing in practical conditions should contribute to animal welfare and them improvement of the productive indicators at the Mexican dry tropics.

Effects of conditioning, source, and rest on indicators of stress in beef cattle transported by road.

Consumers are increasingly concerned about the welfare of farm animals, especially during transportation. The Canadian transport regulations state that weaned cattle require an 8 h rest after 36 h of transport. There are, however, only a few studies that assess the effect of rest on the welfare of beef cattle. The aim of this study was to assess the effect of conditioning, source and rest on indicators of welfare in 7-8-month-old beef calves during long-distance transport. Treatments consisted of a 2 × 2 × 2 factorial design where the main factors were conditioning: conditioned (C; n = 160) or non-conditioned (N; n = 160); source: auction market (A; n = 160) or ranch direct (R; n = 160); and rest: 0 h (0 h; n = 160) or 8 h (8 h; n = 160). Means of non-esterified fatty acids (NEFA), serum amyloid-A, haptoglobin, creatine kinase (CK), and percentage of time standing from N calves were greater than C calves (all p ≤ 0.05). Means of percentage of time standing and CK of R calves were greater than A calves (both p ≤ 0.05). The mean of NEFA of 0 h calves was greater than the 8 h calves (p < 0.01), while the percentage of time standing of 0 h calves was less than 8 h calves (p < 0.01). Statistically significant differences between means of NEFA and standing percentage, were observed between 0 h and 8h calves. Few and inconsistent indicators of reduced welfare were observed between auction market and ranch direct calves, while non-conditioning was associated with greater physiological and behavioural indicators of reduced welfare. Based on these results, conditioning should be implemented as a management practice to improve the welfare of transported calves.

392 Vitamin C and transit stress in beef cattle

Abstract Transportation of cattle by road is unavoidable in beef production due to segmentation of the industry. Psychological and physical stress associated with transit can negatively impact cattle health and performance upon arrival at their destination. Thus, investigation of resiliency or recovery-based nutritional strategies to mitigate transit stress are warranted. Because oxidative stress is likely linked to transportation stress, one such strategy is antioxidants such as vitamin C (VC). Seventy-two Angus-cross steers (356 ± 18 kg) were used to determine the effects of a pre- versus post-transit VC injection on 56 d feedlot performance. Steers were randomly assigned to intramuscular injection treatments (24 steers/treatment): saline pre- and post-transit (CON), VC (Vet One; 250 mg sodium ascorbate/mL; 5 g sodium ascorbate/steer) pre-transit and saline post-transit (PRE), or saline pre-transit and VC post-transit (POST). Steers were transported for ~18 h (1,675 km) prior to sorting into pens equipped with GrowSafe bunks (6 steers/pen). Blood was collected from 12 steers/treatment on d 0, 1, 2, and 7 for analysis of plasma ascorbate concentrations. Plasma ascorbate concentrations were decreased by ~10% immediately post-transit for CON and POST-steers but increased for PRE-steers; regardless of treatment, concentrations were similar to pre-transit values by d 7 (treatment × day; P &amp;lt; 0.01). Steers that received VC at either timepoint (pre- or post-transit) exhibited greater dry matter intake from d 31–57 and d 1–57 compared to CON-steers (P ≤ 0.02). However, PRE-steers exhibited the greatest average daily gain from d 7–31 and d 1–57 (P ≤ 0.05), resulting in PRE-steers being heaviest on d 30/31 (P = 0.03) and tending to be heaviest on d 56/57 (P = 0.07). Based on these data, timing of nutritional intervention is vital for optimal effectiveness. Furthermore, nutritional strategies that improve antioxidant status prior to long-distance transit events may positively influence post-transit performance.

The Effect of Stress on Reproduction and Reproductive Technologies in Beef Cattle-A Review.

Simple SummaryThe economic sustainability of beef herds relies on achieving a reliable percentage of weaned calves. Efforts to lift reproductive efficiency of beef herds have traditionally focused on physical health and nutrition aspects, by extrapolating knowledge from dairy herds. However, animal welfare and stress on beef farms is of outstanding importance. Stress affects the economic sustainability of the farm directly by reducing productive and reproductive performance, as well as indirectly by pushing away customers, who demand farming practices that ensure better animal welfare and lower stress. Despite its relevance and the increasing efforts made by the industry, the detailed ways in which stress influences reproduction of beef herds are still not well understood. Trying to contribute to clarity and reviewing the huge advances made in this topic, we describe the major factors contributing to stress in beef cattle and the effects of that stress on their reproductive performance. We highlight main stressors in beef, such as cattle management, handling stress while passing through the chutes, social hierarchy or weaning effects, besides the nutritional and climate stress and include the acclimatization, acclimation and temperament. We pay attention to the beef bull. And finally, we point out strategies demonstrated to alleviate stressful situations, improving reproductive performance.Researchers have contributed by increasing our understanding of the factors affecting reproduction in beef, mainly physical health and nutrition aspects, which have been main concerns during decades. Animal welfare is of outmost relevance in all animal production systems and it is strongly associated to stress. Stress responses involve endocrine, paracrine and neural systems and the consequences of this stress on the reproductive efficiency of specifically, beef cattle and bulls, need to be highlighted. We, therefore, describe the fundamentals of stress and its quantification, focusing in beef herds, reviewing the highly valuable pieces of research, already implemented in this field. We examine major factors (stressors) contributing to stress in beef cattle and their effects on the animals, their reproductive performance and the success of reproductive biotechnologies. We include terms such as acclimatization, acclimation or temperament, very relevant in beef systems. We examine specifically the management stress due to handling, social environment and hierarchy or weaning effects; nutritional stress; and thermal stress (not only heat stress) and also review the influence of these stressors on reproductive performance and effectiveness of reproductive biotechnologies in beef herds. A final message on the attention that should be devoted to these factors is highlighted.

Effect of prenatal transportation stress on DNA methylation in Brahman heifers

Prenatal stress in beef cattle has the potential to result in unexpected, long-term phenotypic changes to an animal's performance. One possible explanation for this phenomenon is stress-induced epigenetic alterations of the genome (e.g., methylation or histone modifications). The objective of this experiment was to identify differential DNA methylation patterns in prenatally stressed (PNS) Brahman females compared to control animals. Pregnant Brahman cows (n = 48) were transported for 2-h periods at 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 d. A non-transported group (n = 48) was maintained as a control (Control). Methylation of leukocyte DNA from 28-d old heifer calves born following the PNS exposure (Control n = 8, PNS n = 6) was assessed by reduced representation sodium bisulfite sequencing. Mean methylation ratios at locations across the genome in PNS and Control females were compared using Fisher's Exact t-tests. There were 16,377 CG sites, 309 CHG, and 612 CHH (C= cytosine; G= guanine; H = adenine, cytosine or thymine) sites that were differentially methylated in PNS females compared to the Control (P ≤ 0.05). Differentially methylated regions located in promoters of genes were analyzed to identify genetic pathways and biological functions potentially influenced by the alterations. Important pathways (P ≤ 0.05) included those involved in cell signaling, neurological development, cellular development, immune response, and metabolism. Alterations in expression of genes in pathways such as the “Axonal Guidance Signaling”, “Corticotrophin Releasing Hormone Signaling” and the Neurotrophin/TRK Signaling” pathways could change animal phenotypes.

PSVIII-40 Effect of prenatal transportation stress on DNA methylation in Brahman heifers

Abstract Prenatal stress in beef cattle has the potential to result in unexpected, long term phenotypic changes to an animal’s performance. One possible explanation for this phenomenon is stress induced epigenetic changes to the genome (e.g., methylation or histone modifications). The objective of this experiment was to identify differential DNA methylation patterns in prenatally stressed (PNS) Brahman females. Multiparous Brahman cows (n = 48) were transported for a 2hr periods on 60 ± 5, 80 ± 5, 100 ± 5, 120 ± 5, and 140 ± 5 d of gestation. A non-transported group (n = 48) was maintained as a control. DNA was extracted from the white blood cells of their 28-d old heifer calves (Control n = 8, PNS n = 6) and methylation was assessed using reduced representation sodium bisulfite sequencing. Mean methylation ratios at locations across the genome in PNS and Control females were compared using a student’s t-test. Analysis revealed 16,377 CpG sites, 311 CHG, and 612 CHH (C= cytosine; G= guanine; H = adenine, cytosine or thymine) sites that were differentially methylated in PNS females compared to the Control females (P ≤ 0.05). The top 2,000 differentially methylated regions (DMRs) were classified by functional location in introns, exons, CpG islands, promoters, and 5’UTR regions. Methylation differences in these regions are known to cause gene expression differences. The identified regions were analyzed using Ingenuity Pathway Analysis (IPA) in order to identify involvement in canonical pathways. Certain regions identified from the hypermethylated DMRs showed the strongest overlap (P = 1.93E-6) with the complex pathway of axonal guidance signaling (important for neural development). These results suggest that prenatal transportation stress does alter the epigenome of Brahman heifers and can influence biological pathways, potentially impacting animal performance.

57 Impact of weaning strategy on beef cow performance

Abstract It has been shown that physiologic stress in beef cattle can impact animal performance. Weaning stress is recognized as a major stress in a calf’s life. However, less is known of its impacts on the dam or developing fetus, as the dam is at the end of the second trimester at weaning. Therefore, the objective was to investigate the impact of weaning stress on cow performance. A total of 240 cows from two locations were assigned to one of three weaning strategies: abrupt removal of the calf on d 0 (n = 80), d 7 cow-calf fenceline contact (n = 81), and late weaning on d 84 (n = 79). Cows averaged 16 and 24 weeks of gestation on d 0 and d 84 respectively. Weights and BCS were obtained monthly. Behavioral observations occurred over the week before and after weaning for each weaning period. Five late-wean cows per location were milked on d 14 and d 70 to estimate milk yield throughout the late wean period. Data were analyzed using the MIXED procedure of SAS with BW and BCS utilizing repeated measures. Means are declared different at P ≤ 0.05. The ADG over the course of the study was lower (P &lt; 0.05) for the late weaned cows compared to the abrupt weaned cows. This was also reflected by change in body condition where late weaned cows dropped from a 5.7 to a 4.9 (P &lt; 0.05) over the 105 d. Milk production in late weaned cows decreased over time (6.0 and 4.4 kg/d for d 14 and 70, respectively; P = 0.05). Energy expenditure for lactation may have contributed to the drop in BCS of the late weaned compared with the non-lactating cows and could compromise third trimester growth of calf in utero. The results of this study warrant further exploration of the effect of weaning stress on dams and their developing fetuses.

48 Impact of weaning strategy on beef cow performance

Abstract It has been shown that physiologic stress in beef cattle can impact animal performance. Weaning stress is recognized as a major stress in a calf’s life. However, less is known of its impacts on the dam or developing fetus, as the dam is at the end of the second trimester at weaning. Therefore, the objective was to investigate the impact of weaning stress on cow performance. A total of 240 cows from two locations were assigned to one of three weaning strategies: abrupt removal of the calf on d 0 (n = 80), d 7 cow-calf fenceline contact (n = 81), and late weaning on d 84 (n = 79). Cows averaged 16 and 24 weeks of gestation on d 0 and d 84 respectively. Weights and BCS were obtained monthly. Behavioral observations occurred over the week before and after weaning for each weaning period. Five late-wean cows per location were milked on d 14 and d 70 to estimate milk yield throughout the late wean period. Data were analyzed using the MIXED procedure of SAS with BW and BCS utilizing repeated measures. Means are declared different at P ≤ 0.05. The ADG over the course of the study was lower (P &lt; 0.05) for the late weaned cows compared to the abrupt weaned cows. This was also reflected by change in body condition where late weaned cows dropped from a 5.7 to a 4.9 (P &lt; 0.05) over the 105 d. Milk production in late weaned cows decreased over time (6.0 and 4.4 kg/d for d 14 and 70, respectively; P = 0.05). Energy expenditure for lactation may have contributed to the drop in BCS of the late weaned compared with the non-lactating cows and could compromise third trimester growth of calf in utero. The results of this study warrant further exploration of the effect of weaning stress on dams and their developing fetuses.

Understanding heat stress in beef cattle

ABSTRACT Thermal stress is the result of a misbalance between heat produced or gained from the environment and the amount of heat lost to the environment. The level of thermal stress can range from minor or no effect to death of vulnerable animals. Under summertime conditions, thermal stress results in hyperthermia or heat stress. Heat stress in feedlot cattle is a common summertime occurrence in cattle-producing parts of the world (USA, Australia, Brazil, etc.). Effects on animals experiencing heat stress [...]

Minor corral changes and adoption of good handling practices can improve the behavior and reduce cortisol release in Nellore cows.

Inadequate corral facilities and improper handling are major causes of stress in beef cattle. The purpose of this study was to evaluate the effects of minor changes in the corral and adoption of good handling practices on the behavior, cortisol release, and time spent taking blood samples in Nellore cows. Minor corral changes included obstructing the cow's vision when the handler walked deep into the animal's flight zone and the elimination of bright objects, color contrasts, puddles, shadows, and darkness in the corral. Handling was improved by eliminating dogs, electric goads (prods), and yelling, as well as adopting a calm behavior. A total of 141 Nellore cows from two typical extensive livestock farms were studied. The cows were evaluated individually before and after the corral changes. Blood samples were collected in the restraint device for cortisol measurement. The minor corral changes and the adoption of good handling practices result in better results for all variables studied. The results showed differences in the interactions between treatment and ranch for chute score (P=0.0091) and exit score (P<0.0001). The cortisol release was lower (P<0.001) and better for the improved methods, resulting in calmer cows compared to cortisol released before the minor changes (41.03±2.9 vs 60.40±3.8ng/mL). Minor changes made in the corrals and the adoption of good handling practices were effective in improving cow behavior in the chute and in reducing exit velocity, cortisol released, and the time spent taking blood samples.

An investigation of hair cortisol as a measure of long-term stress in beef cattle: results from a castration study

The objectives were to (1) investigate the effectiveness of hair cortisol concentration (HCC) as a measure of long-term stress in beef cattle and (2) determine whether meloxicam would decrease post...

Effect of Summer Annual Forage and Type of Shade on Grazing Behavior of Beef Stocker Heifers

&lt;p&gt;Heat stress in beef cattle is still one of the issues affecting animal performance in the beef cattle industry. Our objective was to evaluate the effect of two summer annual forages such as alyceclover (&lt;em&gt;Alysicarpus vaginalis&lt;/em&gt; L.), and pearl millet (&lt;em&gt;Pennisetum glaucum&lt;/em&gt;) with natural (trees) or artificial shade (80% shade) on grazing behavior and on reducing the heat load of crossbred yearling heifers. On three consecutive years from mid-July to mid-September, 36 (&lt;em&gt;Bos taurus&lt;/em&gt; × &lt;em&gt;B. indicus&lt;/em&gt;) heifers (body weight [BW] = 321±11.3 kg) were randomly allotted (n = 3) and continuously stocked in 12-1.33 ha paddocks in a 2 × 2 factorial arrangement of treatments (2 forage types and 2 shade types) with three replicates. Heifers grazing on alyceclover gained more (p = 0.03) than those grazing pearl millet (0.94 and 0.80 kg, respectively). Grazing behavior variables were not affected (p &amp;gt; 0.05) by forage type and forage type x shade type interaction; however, shade type affected grazing and lying time (p &amp;lt; 0.05). Time of day (TOD) affected (p &amp;lt; 0.05) grazing and standing time, number of steps taken, respiration rate, and panting scores. These negative effects are related with the greatest temperature humidity index between 1100 and 1459 h. When data were analyzed by TOD, the negative effect on grazing behavior variables was not different for heifers with access to natural or artificial shades. Under the conditions of the present experiment, artificial shade provided protection for cattle. Grazing behavior parameters can be used to monitor heat load in grazing cattle.&lt;/p&gt;

The effect of global warming on beef production in developing countries of the southern hemisphere

Developing countries from the southern hemisphere will be confronted by the same beef production challenges caused by global warming, because these countries are at the same geographical positions in southern latitudes. Global warming is expected to have a more extreme effect on the southern hemisphere than on other continents and will have a negative effect on the beef production environments in these countries. The negative effects will include high ambient temperatures, nutritional stress and altered patterns of animal diseases. Heat stress in beef cattle on veld/savannah is expected to increase as a result of changing weather patterns on a global and regional scale. This may negatively influence food production from beef cattle for the human food chain. Negative effects of increased temperatures and thus heat stress can include lower reproductive rates and weaning weights. The effect of heat stress can be partly addressed by nutritional strategies, such as replacing rapid fermentable carbohydrates with saturated fatty acids and the feeding of more by-pass protein and dietary electrolytes. Global warming will also alter the distribution pattern of animal diseases and the vectors of some of these diseases. This may even include the spread to South American countries. Likewise the nutritional value of natural pastures may be influenced. The effect of global warming on the quality of pastures will depend on whether the global warming is a result of increased carbon dioxide levels or not. An improved understanding of the adaptation of beef cattle to their production environments is important, but adaptation is complex and thus difficult to measure. Fortunately, several proxy-indicators for adaptation such as reproductive, production and health traits are available. The selection of animals and genotypes that are better adapted to the production system, including heat stress, is possible and should be persuade to ensure sustainable beef production in hotter climates.