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Mahjoubi E, Yazdi MH, Aghaziarati N, Noori GR, Afsarian O, Baumgard LH. The effect of cyclical and severe heat stress on growth performance and metabolism in Afshari lambs1. J Anim Sci 2015; 93:1632-40. [DOI: 10.2527/jas.2014-8641] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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52
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Effects of different amylose to amylopectin ratios on serum indices related to glucose metabolism and glucose transporter expression in fattening lambs. Anim Feed Sci Technol 2015. [DOI: 10.1016/j.anifeedsci.2015.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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53
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Abstract
Fifty male Merino lambs (6 to 8 weeks, 14.1 kg; n=10 per group) were used to study the effect of feeding system: barley straw in long form and concentrate pellets in separate troughs (Control), ad libitum alfalfa supplemented with concentrate in separate troughs (Alfalfa) or including various levels of ground barley straw in concentrate pellets (B05, B15 and B25 for 50, 150 and 250 g barley straw/kg), on rumen characteristics, acid-base status, blood cell counts and lymphocyte stimulation. Alfalfa lambs had the heaviest digestive tract contents, highest rumen pH values, lowest volatile fatty acid concentration, highest papillae counts and best mucosa colour and the greatest blood pCO2 values, lowest sodium and chloride and highest potassium concentrations (P<0.05). Including ground barley straw in the concentrate pellet or providing straw in long form separately from the concentrate reduces rumen pH and darkens ruminal mucosa as compared with alfalfa-fed lambs, thus affecting acid-base status.
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Blanco C, Giráldez FJ, Prieto N, Morán L, Andrés S, Benavides J, Tejido ML, Bodas R. Effects of dietary inclusion of sunflower soap stocks on nutrient digestibility, growth performance, and ruminal and blood metabolites of light fattening lambs. J Anim Sci 2014; 92:4086-94. [PMID: 25085392 DOI: 10.2527/jas.2014-7693] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Forty-four merino lambs (6 to 8 wk old; BW 15.6 ± 0.21 kg) were used to study the effect of adding different proportions of sunflower soap stock (SS) to pelleted total mixed ration (TMR) for fattening lambs on feed intake, animal growth and dressing percentage, ruminal fluid characteristics, and blood acid-base parameters. Lambs were assigned to 1 of 4 experimental groups (11 lambs per group), each randomly assigned to 1 dietary treatment: 00SS (0 g SS/kg TMR pellet), 15SS (15 g SS/kg TMR pellet), 30SS (30 g SS/kg TMR pellet), and 60SS (60 g SS/kg TMR pellet). Lambs were individually fed the corresponding diet ad libitum. On d 19 to 23, total feces were collected and sampled from 4 lambs per group. When lambs reached 27 kg BW, they were slaughtered. Dry matter intake, ADG, and length of fattening period were not affected by the dietary treatment (P > 0.10). Animals in the 30SS group tended to show the best G:F values (P < 0.10). Dressing percentage tended to linearly decrease as SS increased (P < 0.10). Animals in the 60SS groups showed the lowest DM and fiber digestibility values (P < 0.05). Total VFA contents in ruminal fluid were not affected (P > 0.10), but the propionate proportion linearly increased (P < 0.05), and the acetate to propionate ratio tended to decrease with SS supplementation. Increasing dietary content of SS linearly decreased the cold carcass weight (P < 0.05) but did not affect other measured carcass characteristics. Ruminal fluid pH tended to decrease (P < 0.10) and mucosa color decreased as SS increased in the TMR (P < 0.05). Blood pH and Na concentration increased (P < 0.05), whereas the anion gap, CO2 pressure, and K concentration linearly decreased (P < 0.05) as SS increased. Including more than 30 g SS/kg TMR in the diet for fattening lambs reduces DM and fiber digestibility without affecting feed intake and ADG. The acidotic rumen conditions that induced a darkening of rumen mucosa were counteracted by blood acid-base parameters. The optimum level of inclusion seems to be 30 g SS/kg TMR.
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Affiliation(s)
- C Blanco
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - F J Giráldez
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - N Prieto
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - L Morán
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - S Andrés
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - J Benavides
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - M L Tejido
- Instituto de Ganadería de Montaña (CSIC-Universidad de León), E-24346 Grulleros (León), Spain
| | - R Bodas
- Instituto Tecnológico Agrario de Castilla y León, Finca Zamadueñas, Ctra. Burgos, km 119, E-47071 Valladolid, Spain
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55
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Norouzian MA, Valizadeh R. Effect of forage inclusion and particle size in diets of neonatal lambs on performance and rumen development. J Anim Physiol Anim Nutr (Berl) 2014; 98:1095-101. [PMID: 24661507 DOI: 10.1111/jpn.12183] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 02/21/2014] [Indexed: 11/28/2022]
Abstract
A slaughter experiment was conducted to determine the effects of alfalfa particle size on rumen morphology and performance of lambs. Twenty-four Balouchi lambs aged 21 days (9.1 ± 1.1 kg) were randomly fed control (diet without alfalfa hay; CON) and mixed rations containing 15% finely ground (FINE; 2 mm) and 15% coarsely chopped alfalfa hay (LONG; 3 to 4 cm). After a 63 days feeding period, nine animals (three per treatment) were slaughtered to obtain ruminal tissue samples for morphological analyses. Alfalfa particle size did not affect (p > 0.05) papillae density, height, width, epithelium depth and surface area. Coarse alfalfa decreased the stratum corneum and increased (p < 0.05) muscle depth compared with fine and control diets. Neither DNA content and nor RNA concentration of rumen tissue was affected by feeding different diets. Forage particle size did not affect the blood concentration of glucose, urea nitrogen (BUN), beta-hydroxybutyric acid (BHBA) and non-esterified fatty acids (NEFA). Dry matter intake and feed conversion ratio were higher for control diet; however, there were no significant differences between treatments for average daily gain. These data suggest that coarse alfalfa significantly reduces the stratum corneum and increases muscularity of rumen wall and tended to better feed conversion ratio.
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Affiliation(s)
- M A Norouzian
- Department of Animal Science, College of Abouraihan, University of Tehran, Tehran, Iran
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56
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Pereira MCS, Carrara TVB, da Silva J, Pinto ACJ, Vicari DVF, Pereira FTV, Arrigoni MDB, Millen DD. Effects of different doses of sodium monensin on rumen papillae and tissue histology of feedlot Nellore cattle. ANIMAL PRODUCTION SCIENCE 2014. [DOI: 10.1071/an14193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The experiment was designed to determine the effects of different doses of sodium monensin (MON) on rumen papillae and tissue histology of feedlot Nellore cattle. The experiment was designed as a completely randomised block, replicated 12 times, in which 60 20-month-old yearling Nellore bulls (402.52 ± 33.0 kg) were fed in individual pens for 84 days according to the following doses of MON expressed in ppm (on a dry-matter basis): 0, 9, 18, 27 and 36. The adaptation program consisted of ad libitum feeding of two adaptation diets over a period of 14 days, with concentrate level increasing from 68% to 84% of diet dry matter. Orthogonal contrasts were used to assess linear, quadratic, cubic and quartic relationships between doses of MON and the dependent variable. No significant (P > 0.10) MON effect was observed for number of papillae, mean papillae area, papillae area as a percentage of absorptive surface and rumenitis incidence. However, as the dose of MON increased, the absorptive surface area, papillae surface area and mitotic index were affected (P < 0.05) cubically, in which animals fed 9 and 36 ppm presented larger absorptive surface area and greater number of cells in mitosis. Thus, based on the results, feeding of MON affected rumen papillae and tissue histology of feedlot Nellore cattle. The doses of 9 or 36 ppm of MON should be considered as the most feasible options, because they promote better development of rumen epithelium.
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57
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Influence of intense exercise on acid–base, blood gas and electrolyte status in bulls. Res Vet Sci 2013; 95:623-8. [DOI: 10.1016/j.rvsc.2013.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 03/30/2013] [Indexed: 11/21/2022]
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Chronic heat stress inhibits immune responses to H5N1 vaccination through regulating CD4⁺ CD25⁺ Foxp3⁺ Tregs. BIOMED RESEARCH INTERNATIONAL 2013; 2013:160859. [PMID: 24151582 PMCID: PMC3787559 DOI: 10.1155/2013/160859] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 08/04/2013] [Indexed: 12/24/2022]
Abstract
Chronic heat stress (CHS) is known to have negative impacts on the immune responses in animals and increases their susceptibility to infections including the highly pathogenic avian influenza virus H5N1. However, the role of regulatory T cells (Tregs) in CHS immunosuppression remains largely undefined. In this study, we demonstrated a novel mechanism by which CHS suppressed both Th1 and Th2 immune responses and dramatically decreased the protective efficacy of the formalin-inactivated H5N1 vaccine against H5N1 influenza virus infection. This suppression was found to be associated with the induced generation of CD4+CD25+FoxP3+ Tregs and the increased secretions of IL-10 and TGF-β in CD4+ T cells. Adoptive transfer of the induced Tregs also suppressed the protective efficacy of formalin-inactivated H5N1 virus immunization. Collectively, this study identifies a novel mechanism of CHS immunosuppression mediated by regulating CD4+CD25+Foxp3+ Tregs.
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59
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Liu JH, Xu TT, Liu YJ, Zhu WY, Mao SY. A high-grain diet causes massive disruption of ruminal epithelial tight junctions in goats. Am J Physiol Regul Integr Comp Physiol 2013; 305:R232-41. [PMID: 23739344 DOI: 10.1152/ajpregu.00068.2013] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alterations in rumen epithelial tight junctions (TJs) at the tissue and molecular levels during high-grain (HG) diet feeding are unknown. Here, 10 male goats were randomly assigned to either a hay diet (0% grain; n = 5) or HG diet group (65% grain; n = 5) to characterize the changes in ruminal epithelial structure and TJ protein expression and localization using scanning and transmission electron microscopy, quantitative real-time PCR, Western blot analysis, and immunofluorescence. After 7 wk of feeding, ruminal free LPS in HG group increased significantly (P < 0.001) compared with the hay group, and free LPS in the peripheral blood was detectable with concentrations of 0.8 ± 0.20 EU/ml, while not detectable in the control, suggesting a leakage of LPS into the blood in the HG group. Correspondingly, the HG-fed goats showed profound alterations in ruminal epithelial structure and TJ proteins, depicted by marked epithelial cellular damage and intercellular junction erosion, down-regulation of TJ proteins claudin-4, occludin, and zonula occludens-1 mRNA and protein expression, as well as redistribution of claudin-1, claudin-4, and occludin. Furthermore, these changes in TJ proteins in the HG group were coupled with the upregulation of mRNA levels for the cytokines TNF-α and IFN-γ in the ruminal epithelia. These results demonstrated for the first time that the HG diet feeding caused disruption of ruminal epithelial TJs that was associated with a local inflammatory response in the rumen epithelium. These findings may provide new insights into understanding the role of TJ proteins in the ruminal epithelial immune homeostasis of ruminants.
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Affiliation(s)
- Jun-hua Liu
- Laboratory of Gastrointestinal Microbiology, College of Animal Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
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60
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Steele M, AlZahal O, Walpole M, McBride B. Short communication: Grain-induced subacute ruminal acidosis is associated with the differential expression of insulin-like growth factor-binding proteins in rumen papillae of lactating dairy cattle. J Dairy Sci 2012; 95:6072-6. [DOI: 10.3168/jds.2011-4864] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 06/29/2012] [Indexed: 11/19/2022]
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61
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Steele M, Dionissopoulos L, AlZahal O, Doelman J, McBride B. Rumen epithelial adaptation to ruminal acidosis in lactating cattle involves the coordinated expression of insulin-like growth factor-binding proteins and a cholesterolgenic enzyme. J Dairy Sci 2012; 95:318-27. [DOI: 10.3168/jds.2011-4465] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 09/05/2011] [Indexed: 02/01/2023]
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62
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Steele MA, Croom J, Kahler M, AlZahal O, Hook SE, Plaizier K, McBride BW. Bovine rumen epithelium undergoes rapid structural adaptations during grain-induced subacute ruminal acidosis. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1515-23. [DOI: 10.1152/ajpregu.00120.2010] [Citation(s) in RCA: 187] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alterations in rumen epithelial structure and function during grain-induced subacute ruminal acidosis (SARA) are largely undescribed. In this study, four mature nonlactating dairy cattle were transitioned from a high-forage diet (HF; 0% grain) to a high-grain diet (HG; 65% grain). After feeding the HG diet for 3 wk, the cattle were transitioned back to the original HF diet, which was fed for an additional 3 wk. Continuous ruminal pH was measured on a weekly basis, and rumen papillae were biopsied during the baseline and at the first and final week of each diet. The mean, minimum, and maximum daily ruminal pH were depressed ( P < 0.01) in the HG period compared with the HF period. During the HG period, SARA was diagnosed only during week 1, indicating ruminal adaptation to the HG diet. Microscopic examination of the papillae revealed a reduction ( P < 0.01) in the stratum basale, spinosum, and granulosum layers, as well as total depth of the epithelium during the HG period. The highest ( P < 0.05) papillae lesion scores were noted during week 1 when SARA occurred. Biopsied papillae exhibited a decline in cellular junctions, extensive sloughing of the stratum corneum, and the appearance of undifferentiated cells near the stratum corneum. Differential mRNA expression of candidate genes, including desmoglein 1 and IGF binding proteins 3, 5, and 6, was detected between diets using qRT-PCR. These results suggest that the structural integrity of the rumen epithelium is compromised during grain feeding and is associated with the differential expression of genes involved in epithelial growth and structure.
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Affiliation(s)
- Michael A. Steele
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada
| | - Jim Croom
- Department of Poultry Science, University of North Carolina, Raleigh, North Carolina; and
| | - Melissa Kahler
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada
| | - Ousama AlZahal
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada
| | - Sarah E. Hook
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada
| | - Kees Plaizier
- Department of Animal Science, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Brian W. McBride
- Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada
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63
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Chronic heat stress weakened the innate immunity and increased the virulence of highly pathogenic avian influenza virus H5N1 in mice. J Biomed Biotechnol 2011; 2011:367846. [PMID: 21687549 PMCID: PMC3114565 DOI: 10.1155/2011/367846] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 03/14/2011] [Accepted: 04/01/2011] [Indexed: 01/30/2023] Open
Abstract
Chronic heat stress (CHS) can negatively affect immune response in animals. In this study we assessed the effects of CHS on host innate immunity and avian influenza virus H5N1 infection in mice. Mice were divided into two groups: CHS and thermally neutral (TN). The CHS treatment group exhibited reduced local immunity in the respiratory tract, including the number of pulmonary alveolar macrophages and lesions in the nasal mucosa, trachea, and lungs. Meanwhile, CHS retarded dendritic cells (DCs) maturation and reduced the mRNA levels of IL-6 and IFN-β significantly (P < .05). After the CHS treatment, mice were infected with H5N1 virus. The mortality rate and viral load in the lungs of CHS group were higher than those of TN group. The results suggest that the CHS treatment could suppress local immunity in the respiratory tract and innate host immunity in mice significantly and moderately increased the virulence in H5N1-infected mice.
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64
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Rumen fermentation and histology in light lambs as affected by forage supply and lactation length. Res Vet Sci 2011; 92:247-53. [PMID: 21458834 DOI: 10.1016/j.rvsc.2011.03.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Revised: 03/05/2011] [Accepted: 03/07/2011] [Indexed: 11/22/2022]
Abstract
This study determined whether the rumen fermentation and histology traits may reflect the feeding strategy in light lambs (22-24 kg). Thirty-two single Rasa Aragonesa lambs were assigned to one of four treatments in a 2×2 factorial design. The factors were the inclusion of forage in the diet (alfalfa grazing vs. concentrate-fed indoors) and lactation length (weaning at 13 kg vs. suckling until slaughter). A multivariate canonical analysis discriminated individuals among feeding strategies. The main function differentiated weaned concentrate-fed lambs from the rest according to dorsal sac papillae height, ventral sac muscular layer thickness and the proportion of rumen valerate. The second function differentiated suckling concentrate-fed lambs from the rest according to plasma urea levels. Lactation length played an important role on rumen histology and protein utilization, especially in concentrate-fed lambs. Alfalfa grazing light lambs had similar rumen morphometric measures and fermentation characteristics, regardless of milk access.
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65
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Steele MA, Vandervoort G, AlZahal O, Hook SE, Matthews JC, McBride BW. Rumen epithelial adaptation to high-grain diets involves the coordinated regulation of genes involved in cholesterol homeostasis. Physiol Genomics 2011; 43:308-16. [PMID: 21245418 DOI: 10.1152/physiolgenomics.00117.2010] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The molecular mechanisms underlying rumen epithelial adaption to high-grain (HG) diets are unknown. To gain insight into the metabolic mechanisms governing epithelial adaptation, mature nonlactating dairy cattle (n = 4) were transitioned from a high-forage diet (HF, 0% grain) to an HG diet (65% grain). After the cattle were fed the HG diet for 3 wk, they returned to the original HF diet, which they were fed for an additional 3 wk. Continuous ruminal pH, ruminal short chain fatty acids, and plasma β-hydroxybutyrate were measured on a weekly basis, and rumen papillae were biopsied from the ventral sac to assess alterations in mRNA expression profiles. The subacute form of ruminal acidosis was diagnosed during the first week of the HG period (4.6 ± 1.6 h/day <pH 5.6), but not during weeks 2 and 3, thereby indicating ruminal adaption to the HG diet. Changes in the mRNA expression profile of rumen papillae were initially examined using Bovine Affymetrix microarrays; a total of 521 differentially expressed genes (false discovery rate P < 0.08) were uncovered from the first to third week of the HG period. Ingenuity Pathway Analysis of microarray results revealed that enzymes involved in cholesterol synthesis were coordinately downregulated from the first to third week of the HG period. In addition, the LXR/RXR activation pathway was significant and included several genes involved in intracellular cholesterol homeostasis. The differential expression signature of eight genes representing the key regulatory points of cholesterol homeostasis was confirmed by quantitative real-time PCR. Based upon our pathway and network results we propose a model to explain cellular events during rumen epithelial adaptation to HG diets and thus provide molecular targets that may be useful in the treatment and prevention of ruminal acidosis.
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Affiliation(s)
- Michael A Steele
- Department of Animal and Poultry Science, University of Guelph, Guelph, Canada
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66
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Changes in serum calcium, phosphorus, and magnesium levels in captive ruminants affected by diet manipulation. J Zoo Wildl Med 2010; 41:404-8. [PMID: 20945636 DOI: 10.1638/2009-0001.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A combination of low serum calcium (Ca), high serum phosphorus (P), and low serum magnesium (Mg) has been observed in individual captive ruminants, primarily affecting kudu (Tragelaphus strepsiceros), eland (Taurotragus oryx), nyala (Tragelaphus angasii), bongo (Tragelaphus eurycerus), and giraffe (Giraffa camelopardalis). These mineral abnormalities have been associated with chronic laminitis, acute tetany, seizures, and death. Underlying rumen disease secondary to feeding highly fermentable carbohydrates was suspected to be contributing to the mineral deficiencies, and diet changes that decreased the amount of starch fed were implemented in 2003. Serum chemistry values from before and after the diet change were compared. The most notable improvement after the diet change was a decrease in mean serum P. Statistically significant decreases in mean serum P were observed for the kudu (102.1-66.4 ppm), eland (73.3-58.4 ppm), and bongo (92.1-64.2 ppm; P < 0.05). Although not statistically significant, mean serum P levels also decreased for nyala (99.3-86.8 ppm) and giraffe (82.6-68.7 ppm). Significant increases in mean serum Mg were also observed for kudu (15.9-17.9 ppm) and eland (17.1-19.7 ppm). A trend toward increased serum Mg was also observed in nyala, bongo, and giraffe after the diet change. No significant changes in mean serum Ca were observed in any of the five species evaluated, and Ca was within normal ranges for domestic ruminants. The mean Ca:P ratio increased to greater than one in every species after the diet change, with kudu, eland, and bongo showing a statistically significant change. The results of this study indicate that the diet change had a generally positive effect on serum P and Mg levels.
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67
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Speakman JR, Król E. The heat dissipation limit theory and evolution of life histories in endotherms--time to dispose of the disposable soma theory? Integr Comp Biol 2010; 50:793-807. [PMID: 21558242 DOI: 10.1093/icb/icq049] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A major factor influencing life-history strategies of endotherms is body size. Larger endotherms live longer, develop more slowly, breed later and less frequently, and have fewer offspring per attempt at breeding. The classical evolutionary explanation for this pattern is that smaller animals experience greater extrinsic mortality, which favors early reproduction at high intensity. This leads to a short lifespan and early senescence by three suggested mechanisms. First, detrimental late-acting mutations cannot be removed because of the low force of selection upon older animals (mutation accumulation). Second, genes that promote early reproduction will be favored in small animals, even if they have later detrimental effects (antagonistic pleiotropy). Third, small animals may be forced to reduce their investment in longevity assurance mechanisms (LAMs) in favor of investment in reproduction (the disposable soma theory, DST). The DST hinges on three premises: that LAMs exist, that such LAMs are energetically expensive and that the supply of energy is limited. By contrast, the heat dissipation limit (HDL) theory provides a different conceptual perspective on the evolution of life histories in relation to body size. We suggest that rather than being limited, energy supplies in the environment are often unlimited, particularly when animals are breeding, and that animals are instead constrained by their maximum capacity to dissipate body heat, generated as a by-product of their metabolism. Because heat loss is fundamentally a surface-based phenomenon, the low surface-to-volume ratio of larger animals generates significant problems for dissipating the body heat associated with reproductive effort, which then limits their current reproductive investment. We suggest that this is the primary reason why fecundity declines as animal size increases. Because large animals are constrained by their capacity for heat dissipation, they have low reproductive rates. Consequently, only those large animals living in habitats with low extrinsic mortality could survive leading to the familiar patterns of life-history trade-offs and their links to extrinsic mortality rates. The HDL theory provides a novel mechanism underpinning the evolution of life history and ageing in endotherms, and makes a number of testable predictions that directly contrast with the predictions arising from the DST.
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Affiliation(s)
- John R Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue 2, Aberdeen AB242TZ, Scotland, UK.
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68
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Speakman JR, Król E. Maximal heat dissipation capacity and hyperthermia risk: neglected key factors in the ecology of endotherms. J Anim Ecol 2010; 79:726-46. [PMID: 20443992 DOI: 10.1111/j.1365-2656.2010.01689.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
1. The role of energy in ecological processes has hitherto been considered primarily from the standpoint that energy supply is limited. That is, traditional resource-based ecological and evolutionary theories and the recent 'metabolic theory of ecology' (MTE) all assume that energetic constraints operate on the supply side of the energy balance equation. 2. For endothermic animals, we provide evidence suggesting that an upper boundary on total energy expenditure is imposed by the maximal capacity to dissipate body heat and therefore avoid the detrimental consequences of hyperthermia--the heat dissipation limit (HDL) theory. We contend that the HDL is a major constraint operating on the expenditure side of the energy balance equation, and that processes that generate heat compete and trade-off within a total boundary defined by heat dissipation capacity, rather than competing for limited energy supply. 3. The HDL theory predicts that daily energy expenditure should scale in relation to body mass (M(b)) with an exponent of about 0.63. This contrasts the prediction of the MTE of an exponent of 0.75. 4. We compiled empirical data on field metabolic rate (FMR) measured by the doubly-labelled water method, and found that they scale to M(b) with exponents of 0.647 in mammals and 0.658 in birds, not significantly different from the HDL prediction (P > 0.05) but lower than predicted by the MTE (P < 0.001). The same statistical result was obtained using phylogenetically independent contrasts analysis. Quantitative predictions of the model matched the empirical data for both mammals and birds. There was no indication of curvature in the relationship between Log(e) FMR and Log(e)M(b). 5. Together, these data provide strong support for the HDL theory and allow us to reject the MTE, at least when applied to endothermic animals. 6. The HDL theory provides a novel conceptual framework that demands a reframing of our views of the interplay between energy and the environment in endothermic animals, and provides many new interpretations of ecological and evolutionary phenomena.
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Affiliation(s)
- John R Speakman
- Institute of Biological and Environmental Sciences, University of Aberdeen, Tillydrone Avenue 2, Aberdeen, Scotland, UK
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69
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Hales KE, McMeniman JP, Leibovich J, Vasconcelos JT, Quinn MJ, May ML, DiLorenzo N, Smith DR, Galyean ML. Effects of varying bulk densities of steam-flaked corn and dietary roughage concentration on in vitro fermentation, performance, carcass quality, and acid-base balance measurements in finishing steers1. J Anim Sci 2010; 88:1135-47. [DOI: 10.2527/jas.2009-2400] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Xue Y, Liao SF, Son KW, Greenwood SL, McBride BW, Boling JA, Matthews JC. Metabolic acidosis in sheep alters expression of renal and skeletal muscle amino acid enzymes and transporters1. J Anim Sci 2010; 88:707-17. [DOI: 10.2527/jas.2009-2101] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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71
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Banerjee Mustafi S, Chakraborty PK, Dey RS, Raha S. Heat stress upregulates chaperone heat shock protein 70 and antioxidant manganese superoxide dismutase through reactive oxygen species (ROS), p38MAPK, and Akt. Cell Stress Chaperones 2009; 14:579-89. [PMID: 19291423 PMCID: PMC2866949 DOI: 10.1007/s12192-009-0109-x] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 02/12/2009] [Accepted: 02/19/2009] [Indexed: 11/28/2022] Open
Abstract
Chinese hamster lung fibroblasts V79 cells were treated with heat stress for 4 weeks with short duration (15 min) heat shock every alternate day in culture. It was observed that Hsp 70 and the antioxidant enzyme MnSOD became overexpressed during the chronic heat stress period. Both p38 MAPK and Akt became phosphorylated by chronic heat stress exposure. Simultaneous exposure to SB203580, a potent and specific p38MAPK inhibitor drastically inhibited the phosphorylation of p38MAPK and Akt. Furthermore, exposure to SB203580 also blocked the increase in Hsp70 and MnSOD levels and the elevated SOD activity brought about by chronic heat stress. Heat shock factor 1 (HSF1) transcriptional activity and nuclear translocation of HSF1 were prominently augmented by chronic heat stress, and this amplification is markedly reduced by concomitant exposure to SB203580. Also, activations of p38MAPK and Akt and upregulations of Hsp70 and MnSOD were observed on exposure to heat shock for a single exposure of longer duration (40 min). siRNA against p38MAPK notably reduced Akt phosphorylation by single exposure to heat stress and drastically diminished the rise in Hsp70 and MnSOD levels. Similarly, siRNA against Akt also eliminated the augmentation in Hsp70 and MnSOD levels but p38MAPK levels remained unaffected. Heat stress produced reactive oxygen species (ROS) in V79 fibroblasts. N-acetyl cysteine blocked the increase in phosphorylation of p38MAPK, amplification of Hsp70, and MnSOD levels by heat stress. Therefore, we conclude that heat stress-activated p38MAPK which in turn activated Akt. Akt acted downstream of p38MAPK to increase Hsp70 and MnSOD levels.Concise summary: Thermal injury of the skin over a long period of time has been associated with development of cancerous lesions. Also, in many cancers, the cytoprotective genes Hsp70 and MnSOD have been found to be overexpressed. Therefore, we considered it important to identify the signaling elements upstream of the upregulated survival genes in heat stress. We conclude that heat stress activated p38MAPK which in turn activated Akt. Akt mediated an augmentation in Hsp70 and MnSOD levels working downstream of p38MAPK.
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Affiliation(s)
- Soumyajit Banerjee Mustafi
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear physics, 1/AF Bidhan Nagar, Kolkata, 700064 India
| | - Prabir Kumar Chakraborty
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear physics, 1/AF Bidhan Nagar, Kolkata, 700064 India
| | - Rakhi Sharma Dey
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear physics, 1/AF Bidhan Nagar, Kolkata, 700064 India
| | - Sanghamitra Raha
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear physics, 1/AF Bidhan Nagar, Kolkata, 700064 India
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72
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Steele MA, AlZahal O, Hook SE, Croom J, McBride BW. Ruminal acidosis and the rapid onset of ruminal parakeratosis in a mature dairy cow: a case report. Acta Vet Scand 2009; 51:39. [PMID: 19840395 PMCID: PMC2770524 DOI: 10.1186/1751-0147-51-39] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 10/19/2009] [Indexed: 11/23/2022] Open
Abstract
A mature dairy cow was transitioned from a high forage (100% forage) to a high-grain (79% grain) diet over seven days. Continuous ruminal pH recordings were utilized to diagnose the severity of ruminal acidosis. Additionally, blood and rumen papillae biopsies were collected to describe the structural and functional adaptations of the rumen epithelium. On the final day of the grain challenge, the daily mean ruminal pH was 5.41 ± 0.09 with a minimum of 4.89 and a maximum of 6.31. Ruminal pH was under 5.0 for 130 minutes (2.17 hours) which is characterized as the acute form of ruminal acidosis in cattle. The grain challenge increased blood beta-hydroxybutyrate by 1.8 times and rumen papillae mRNA expression of 3-hydroxy-3-methylglutaryl-coenzyme A synthase by 1.6 times. Ultrastructural and histological adaptations of the rumen epithelium were imaged by scanning electron and light microscopy. Rumen papillae from the high grain diet displayed extensive sloughing of the stratum corneum and compromised cell adhesion as large gaps were apparent between cells throughout the strata. This case report represents a rare documentation of how the rumen epithelium alters its function and structure during the initial stage of acute acidosis.
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73
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Xu M, Dong Y, Du S, Hao Y, Wang Y, Wang F, Yao J. Effect of corn particle size on mucosal morphology and digesta pH of the gastrointestinal tract in growing goats. Livest Sci 2009. [DOI: 10.1016/j.livsci.2008.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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74
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Wang Y, Xu M, Wang F, Yu Z, Yao J, Zan L, Yang F. Effect of dietary starch on rumen and small intestine morphology and digesta pH in goats. Livest Sci 2009. [DOI: 10.1016/j.livsci.2008.07.024] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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75
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Las JE, Odongo NE, Lindinger MI, AlZahal O, Shoveller AK, Matthews JC, McBride BW. Effects of dietary strong acid anion challenge on regulation of acid-base balance in sheep1. J Anim Sci 2007; 85:2222-9. [PMID: 17504956 DOI: 10.2527/jas.2007-0036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The acid-base status of the extracellular fluid is directly affected by the concentrations of strong basic cations and strong acid anions that are absorbed into the bloodstream from the diet. The objective of this study was to develop and characterize a model for dietary acid challenge in sheep by decreasing the dietary cation-anion difference (DCAD) using NutriChlor (HCl-treated canola meal), an anionic feed supplement. Ten fully fleeced sheep (Rideau-Arcott, 54.3 +/- 6.7 kg of BW) were fed either a control supplement [200 g/d of canola meal, DCAD = 184 mEq/kg of DM, calculated as (Na+ + K+) - (Cl- + S2-)] or an anionic supplement (AS; 200 g/d of NutriChlor, DCAD = -206 mEq/kg of DM) offered twice daily at 0700 and 1100 in a randomized complete block design. The sheep were individually housed and limit-fed a basal diet of dehydrated alfalfa pellets (22% CP and 1.2 Mcal of NE(g)/kg, DM basis) at 1.1 kg of DM/d offered twice daily at 1000 and 1300. Two days before the beginning of the experiment, the sheep were fitted with vinyl catheters (0.86-mm i.d., 1.32-mm o.d.) in the left jugular vein to facilitate blood sampling. Blood and urine samples were obtained daily from 1100 to 1130 on d 1 through 9 and at 0700, 1000, 1300, 1600, and 1900 on d 10. Blood was analyzed for hematocrit, plasma pH, gases, strong ions, and total protein. Urine samples were analyzed for pH. The AS induced a nonrespiratory acid-base disturbance associated with lower (P < 0.05) plasma pH (7.47 vs. 7.39), lower (P < 0.05) urine pH (8.13 vs. 6.09), and lower (P < 0.05) strong ion difference (42.5 vs. 39.5). The AS reduced (P < 0.05) the concentration of plasma glucose, base excess, and bicarbonate and increased (P < 0.05) the concentration of K+ and Cl-. Lowering DCAD increased (P < 0.05) Ca2+ concentrations in plasma by 13%. In conclusion, this dietary model successfully induced a significant acid-base disturbance in sheep. Although the acidifying effects of negative DCAD in the diet may have short-term prophylactic effects of elevating the concentration of Ca2+ in plasma, negative DCAD may have detrimental effects on acid-base balance.
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Affiliation(s)
- J E Las
- Department of Animal and Poultry Science, University of Guelph, Ontario, Canada, N1G 2W1
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