This survey was conducted to find the effects of either dietetic Se ( Se ) beginning or dose on a scope of dairy cow metabolic and haematological profiles and their subsequent relationship with oxidative position and environmental temperature. Forty lactating cattles, offered the same basal diet, were blocked by yearss in milk, milk output and para and so indiscriminately allocated to 1 of 5 dietetic interventions: negative control ( CTRL ; 0.098 milligram Se kga?’ 1 DM ) , two degrees of Se yeast ( SY ) supplementation ( 0.31 and 0.50 milligrams entire Se kga?’ 1 DM ) , and two degrees of Na selenite ( SS ) supplementation ( 0.31 and 0.50 milligrams entire Se kga?’ 1 DM ) . Whole blood samples were taken from all animate beings at the start of the survey ( 23 March ) and after 28, 56, 84, 112, 126, and 140 d. Whole blood samples were analyzed for entire Se, glutathione peroxidase ( GPX-1 ) and a scope of haematological parametric quantities. Plasma was analyzed for entire Se, glutathione peroxidase ( GPX-3 ) , metabolites related to energy and protein metamorphosis, concentration of minerals, enzyme activities, positive ague stage proteins and oxidative position markers. Glutathione peroxidase activity and entire Se in whole blood and plasma were greater ( P & lt ; 0.001 ) in Se supplemented cattles than CTRL. The temperature humidness index ( THI ) values indicate that during the test cattles experienced a slight-mild heat emphasis. A negative consequence of THI on plasma glucose, non-esterified fatty acids ( NEFA ) , thiol groups, plasma Na and K, and leucocyte count was observed. Conversely, a positive consequence of THI on aspartate transaminase ( AST ) activity and GPX-3 activity was observed. Lower values ( P & lt ; 0.05 ) of thiobarbituric acid reactive substances ( TBARS ) during the hotter period were observed in SY supplemented animate beings when compared with CTRL and SS. Furthermore, plasma entire antioxidants were lower ( P & lt ; 0.05 ) in SY supplemented animate beings when compared with SS during the hotter period. Plasma reactive O metabolites were besides numerically lower in SY when compared to SS. These consequences could be interpreted as an betterment in the preventative antioxidant systems of cattles fed Se barm.
Cardinal words: dairy cow, Se, heat emphasis, metabolic conditions, haematological profile.
It is good known that high environmental temperatures negatively affect production and reproduction in dairy cattles ( Jordan, 2003 ; West, 2003 ) . Similar observations in dairy cattles have been reported for temperate countries such as Italy ( Calamari and Mariani, 1998 ; Bernabucci et al. , 2002 ) .
Heat emphasis has been reported to bring on the production of O derived free groups, ensuing in some of the hurtful effects associated with heat emphasis ( Loven, 1988 ) . Nevertheless, surveies on the effects of heat emphasis on markers of oxidative position in cowss are contradictory. Harmon et Al. ( 1997 ) reported a decrease in antioxidant activity of plasma, while Calamari et Al. ( 1999 ) observed merely weak negative effects on some plasma markers of oxidative position in mid-lactating Holstein cattles. Lakritz et Al. ( 2002 ) observed a lessening in the decreased glutathione content with a commensurate addition in oxidised glutathione content in whole blood of grownup cattles. Trout et Al. ( 1998 ) reported no effects of heat emphasis on plasma concentrations of vitamin E and I?-carotene and on musculus thiobarbituric acid reactive substances. Bernabucci et Al. ( 2002 ) observed that season did non modify plasma oxidative markers, although some erythrocyte markers of oxidative position indicated oxidative emphasis in passage dairy cattles during the summer when compared to those during spring.
Free groups compromise cellular map by taking negatrons from a assortment of molecules. As a consequence protein crosslinking, DNA harm, and lipid peroxidation ( Dargel, 1992 ) , and break of normal metamorphosis and physiology ( Trevisan et al. , 2001 ) can happen. Lacks of natural protective substances or extra exposure to stimulators of free extremist production may ensue in oxidative emphasis. When the production of free groups is faster than their neutralisation by antioxidative mechanisms, oxidative emphasis is induced ( Surai, 2006 ) . These conditions can lend to the oncoming of wellness upsets in cowss ( Miller et al. , 1993 ) .
Natural and man-made antioxidants in the provender every bit good as optimum degrees of minerals, chiefly Se, aid to keep efficient degrees of endogenous antioxidants in tissues. Selenium protects tissues against oxidative emphasis ( Surai, 2006 ) , as it is a constituent of the glutathione peroxidase ( GPX ) enzyme ( Rotruck et al. , 1973 ) , which destroys free groups in the cytol ( MacPherson, 1994 ) . Selenium has been shown to cut down wellness upsets and heighten the immune system ( Hernken et al. , 1998 )
A battalion of informations is available on the effects of Se supplementation in heat stressed animate beings ( Rochet and Mazzia, 2008 ) , but small informations exists on the effects of Se barm compared with selenite. Thatcher ( 2006 ) reported an addition in immunocompetence at birth, an betterment in uterine wellness and 2nd service gestation rate during the summer months in cattles fed Se yeast prior to break uping. Increased neutrophil map, improved immuno-responsiveness and uterine wellness, and increased 2nd service gestation rate during summer in a selenium-deficient environment were observed by Silvestre et Al. ( 2007 ) in cattles supplemented Se-yeast in Florida.
The purpose of the current survey was to measure the effects of feeding diets incorporating either no Se supplementation, or two Se beginnings ( Se yeast and sodium selenite ) at two different doses ( 0.31 and 0.50 milligrams entire Se kg DM-1 ) to mid lactation dairy cattles and the subsequent effects on metabolic and haematological profiles and their relationships with oxidative position and environmental temperature.
2. Materials and methods
2.1. Animal and direction conditions
The research protocol and the animate being attention were in conformity with the EC Council Directive guidelines for animate beings used for experimental and other scientific intents ( European Community, 1986 ) .
The Italian Friesian dairy cattles involved in this survey were raised in a free stall barn at the experimental farm “ Vittorio Tadini ” , located near Piacenza ( 45A°01’N, 9A°40’E ; height 68 m ASL ) ( Italy ) . Cattles were raised in pens keeping 12-16 cattles each, dwelling of a resting country with cells and, outdoors, an unshaded difficult tribunal paddock. In each pen fresh drinkable H2O was available ad libitum. Description of lodging and farming was reported antecedently ( Calamari et al. , 2010 ) . Furthermore, each pen was equipped with 2 axial flow fans ( 0.75 kilowatt ; 90 centimeter diameter ; 22500 m3 h-1 maximal airflow rate ) installed along the provender private road. Fans were mounted at a tallness of about 2.5 m and angled downward at approximately 10 grades from perpendicular. The variable velocity fans were thermostatically controlled and were switched on at 23A° C and reached maximal flowrate at 27A° C. Sprinklers ( bringing rate of 4 L min-1 and a force per unit area of 150-200 kPa ) spaced at 150 centimeter intervals were placed perpendicular to the air flow of the fans along the provender back street. The sprinklers were thermostatically controlled to 27A°C in an uneven manner: 50 seconds of showering and airing followed by 5 proceedingss of airing entirely.
Feeding direction and diet composing were besides reported antecedently ( Calamari et al. , 2010 ) . Samples of eatages and dressed ore mixes were collected twice monthly, whilst TMR samples were collected hebdomadally. All samples were pooled monthly for the analyses.
2.2. Experimental design
The survey was conducted on 40 cattles that received the same basal diet ( dietetic concentration of 0.10 milligrams entire Se kg DM-1 ) that differed in merely Se beginning ( Se yeast or sodium selenite ) or dose ( 0.31 or 0.50 mg entire Se kg DM-1 ) . The period of Se supplementation lasted 140 vitamin D ( from March 23, 2007 to August 10, 2007 ) . Cattles were blocked by age, milk output and twenty-four hours in milk ( DIM ) and indiscriminately allocated to one of 5 dietetic interventions ( 8 cattles per intervention ) : negative control ( CTRL, background Se merely ) , Se yeast supplementation [ Sel-PlexA® Se barm ( Saccharomyces cerevisiae CNCM I-3060 ) incorporating 63 % SeMet ( Alltech, Nicholasville, KY ) ] to accomplish either 0.31 and 0.50 milligram of entire Se kilogram DM-1 ( SY03 and SY05, severally ) , or Na selenite supplementation to accomplish either 0.31 and 0.50 milligram of entire Se kilogram DM-1 ( SS03 and SS05, severally ) ( Table 1 ) . Average break uping figure and average DIM of cattles of each intervention were reported antecedently ( Calamari et al. , 2010 ) . Entire assorted rations, which contained the Se addendums, were prepared fresh day-to-day and offered to the cattles of each intervention. The Se addendum was added to the commixture waggon utilizing maize repast as a bearer to obtain the right concentration of Se for each dietetic intervention.
2.3. Measurements and trying
2.3.1. Microclimatic conditions.
Temperature and comparative humidness of the interior barn were recorded daily during the survey period utilizing 2 electronic investigations ( Gemini Data Logger, UK ) connected to a information lumberman programmed to enter every 10 min. Average day-to-day temperature and humidness and day-to-day lower limit and maximal temperature and humidness were calculated from temperature and comparative humidness informations recorded throughout the test. Datas were used to calculate a composite climatic public assistance index, the Temperature Humidity Index ( THI ) , harmonizing to the expression of Kelly and Bond, as reported by Ingraham et Al. ( 1979 ) . Average day-to-day THI ( AVG THI ) , day-to-day minimal THI ( MIN THI ) , day-to-day upper limit THI ( MAX THI ) , and the mean THI of the hebdomad before each blood sampling ( WK THI ) were calculated throughout the test and heat emphasis was estimated harmonizing to Armstrong ( 1994 ) . In add-on, the happening of heat moving ridges was detected harmonizing to Hahn et Al. ( 1999 ) .
2.3.2. Blood sampling.
Blood samples on all cattles were obtained before feeding at the start of the test ( 23 March T0 ) and after 28 ( April: T28 ) , 56 ( May: T56 ) , 84 ( 18 June: T84 ) , 112 ( 11 July: T112 ) , 126 ( 25 July: T126 ) and 140 vitamin D ( 8 August: T140 ) of Se supplementation. At each trying point, 3 blood samples were collected by venepuncture from the jugular vena: two 10-mL Li-heparin treated tubings ( Vacuette, incorporating 18 IU of Li-heparin mL-1, Kremsmunster, Austria ) and one 3-mL K3EDTA treated tubings ( Venojet, incorporating 2.1 g of K3EDTA ml-1, Terumo, Leuven, Belgium ) . Blood samples were instantly placed into an ice-bath before processing.
2.4. Lab analyses
2.4.1. Selenium content in provenders, entire Se and glutathione peroxidase in whole blood.
Selenium content of the specific premixes and composite feedstuffs was determined on mineralized samples utilizing ICP-MS ( Inductively Coupled Plasma Mass Spectrometry, Elan 6100, Perkin Elmer, Norwood, MA ) . The first Li-heparin treated tubing of whole blood was used to mensurate entire Se and glutathione peroxidase ( GPX-1 ) activity as described by Calamari et Al. ( 2010 ) .
2.4.2. Plasma metabolic profile and Se content.
The 2nd Li-heparin treated tubing was centrifuged ( 3500 x g for 15 min at 10A°C ) and plasma separated and instantly stored at -20A°C until analysis. Plasma metabolites were analyzed at 37A°C by an machine-controlled clinical analyser ( ILAB 600, Instrumentation Laboratory, Lexington, MA ) . Analysis for glucose, urea, Ca, inorganic P, Mg, entire protein, albumen, entire hematoidin, and creatinine were conducted utilizing commercial kits ( Instrumentation Laboratory, Lexington, MA ) , besides Zn ( Wako Chemicals GmbH, Neuss, Germany ) . Enzymatic analysis for entire cholesterin and triglycerides were conducted utilizing commercial kits ( Instrumentation Laboratory, Lexington, MA ) . A potentiometric system, with specific electrodes, was employed to find Na, K, and Cl. Plasma thiol groups ( SHp ) were analyzed utilizing commercial kits ( Diacron International, Grosseto, Italy ) , as described by Bernabucci et Al. ( 2005 ) . Entire plasma antioxidants ( TA ) were analyzed using a commercial kit ( Oxy-Adsorbent trial, Diacron International, Grosseto, Italy ) , harmonizing to Trotti et Al. ( 2001 ) . The Oxy-Adsorbent trial assesses the antioxidant power of the plasma barrier by mensurating the ability of the barrier to oppose the monolithic oxidant action of hypochlorous acid ( HClO ) . Consequences are expressed as micromoles of HClO mL-1 staying after the reaction. Entire plasma reactive O metabolites ( ROM ) were measured utilizing a commercial kit ( d-ROMs trial, Diacron International, Grosseto, Italy ) , harmonizing to Bernabucci et Al. ( 2005 ) . Consequences are expressed as mgs of H peroxide per 100 milliliter of plasma. This reagent kit steps non merely ROM bing in the matrix, but besides the species developing during the Fenton reaction ( Oriani et al. , 2001 ) . The thiobarbituric acid-reacting substances ( TBARS ) were measured with fluorimetric method harmonizing to Yagi ( 1976 ) . Plasma glutathione peroxidase ( GPX-3 ) was determined harmonizing to the method of Paglia and Valentine ( 1967 ) utilizing a commercial kit ( Ransel kit, Randox, UK ) . Kinetic analysis was adopted to find activity of glutamate dehydrogenase ( GDH, EC 126.96.36.199 ) utilizing a commercial kit ( Randox Laboratories, Antrim, UK ) , and alkalic phosphatase ( AP, EC 188.8.131.52 ) , aspartate transaminase ( AST, EC 184.108.40.206 ) , i?§-glutamyltransferase ( GGT, EC 220.127.116.11 ) , L-lactate dehydrogenase ( LDH, EC 18.104.22.168 ) , alanine transaminase ( ALT, EC 22.214.171.124 ) , creatine kinase ( CK, EC 126.96.36.199 ) findings were besides conducted utilizing commercial kits ( Instrumentation Laboratory, Lexington, MA ) . Entire bilirubin concentration in plasma was determined utilizing commercial kits ( Instrumentation Laboratory, Lexington, MA ) . Ceruloplasmin ( Cp ) and haptoglobin were determined with reagents prepared harmonizing to the method reported by Bertoni et Al. ( 1998 ) . Entire Se content in plasma was analyzed as described by Calamari et Al. ( 2010 ) .
2.4.3. Hematologic Profile.
The K3EDTA treated tubing of whole blood was used to mensurate the haematological profile utilizing a Cell-Dyn 3700 haematology analyser ( Abbott Diagnostici, Roma, Italy ) . The measurings were: entire ruddy blood cells figure ( RBC ; M i?L-1 ) ; haemoglobin ( HGB ; g dL-1 ) ; haematocrit ( HCT ; % ) ; average corpuscular volume ( MCV ; Florida ) ; average corpuscular haemoglobin ( MCH ; pg ) ; average corpuscular haemoglobin concentration ( MCHC ; g dL-1 ) ; breadth of RBC volume distribution ( RDW ; % ) ; entire white blood cells figure ( WBC ; K i?L-1 ) ; neutrophils ( NEU ; K i?L-1 and % on WBC ) ; lymphocytes ( LYM ; K i?L-1 and % on WBC ) ; monocytes ( MON ; K i?L-1 and % on WBC ) ; eosinophils ( EOS ; K i?L-1 and % on WBC ) ; basophils ( BAS ; K i?L-1 and % on WBC ) ; entire thrombocyte figure ( PLT ; K i?L-1 ) ; average thrombocyte volume ( MPV ; Florida ) .
2.5. Statistical analysis
Consequences were analyzed utilizing the MIXED theoretical accounts process ( SAS Inst. Inc. , Cary, NC ) harmonizing to Littell et Al. ( 1998 ) . Beginnings of fluctuation included intervention consequence ( 5 degrees ) , clip, intervention ten clip interaction and the uninterrupted random consequence of THI ( WK THI ) . The random variable was cow within intervention. Pre-experimental informations were used for covariate accommodation. Each variable analyzed was subjected to 3 covariance constructions: Autoregressive Order, Compound Symmetry, and Spatial Power ( Littell et al. , 1998 ) . Using the lowest Akaike ‘s information standard and Schwarz Bayesian standard, the Spatial Power was the covariance construction that fitted the theoretical account best. Consequences are presented in tabular arraies as least square agencies and standard mistake of the mean ( SEM ) . If a important consequence of dietetic intervention or THI was detected, comparings were made between any intervention means during the hotter period ( T112, T126, and T142 ) as follows: 1 ) CTRL vs. other interventions ( SY03, SY05, SS03, and SS05 ) to measure the effects of Se supplementation ; 2 ) Se barm supplementation ( SY03 and SY05 ) vs. selenite supplementation ( SS03 and SS05 ) to measure beginning consequence ; 3 ) low degree ( SY03 and SS03 ) vs. high degree of Se supplementation ( SY05 and SS05 ) to measure the dose consequence.
Correlation coefficients between the mensural variables were besides calculated foremost for the planetary dataset and so individually within CTR + SS03 + SS05 and within CTR + SY03 + SY05. Consequences were presented as important when differences between values differ for P & lt ; 0.05 ; a tendency was considered when P & lt ; 0.10.
3.1. diet features and Se content
The concentration of entire Se in the negative control diet was 0.098 A± 0.027 milligram Se kg DM-1 and was similar to estimated values before the beginning of the survey ( Table 1 ) . Chemical and alimentary features of the basal diet used in this survey, and the Se content of the TMR of each intervention have already been reported by Calamari et Al. ( 2010 ) . Consequences on Se position ( entire blood Se, entire plasma Se, and GPX-1 activity ) obtained in this survey have besides been reported by Calamari et Al. ( 2010 ) .
Overall mean values of milk output have already been reported by Calamari et Al. ( 2010 ) , and neither beginning nor dose effects were observed. At the start of the survey ( T0 ) , mean day-to-day milk output was 34.91 A± 1.71 kilogram da?’ 1 and dropped to 28.14 A± 1.71 kilograms da?’ 1 at the terminal of the survey ( T140 ) , with an mean rate of diminution of approximately 4.43 % per month. The rate of diminution showed high variableness through the experimental period. Greater rates of diminution were observed between T56 and T84 ( 10.23 % per month ) and between T112 and T140 ( 9.94 % per month ) .
3.2. Microclimatic conditions
The class of day-to-day minimal and maximal THI during the experimental period is shown in Figure 1. The period during which the cattles experienced day-to-day MAX THI above 72 was from terminal of April to early August. Cattles were exposed to day-to-day AVG THI greater than 72 from early July to the terminal of July, during which clip average day-to-day THI was 72.23 A± 2.69. Then, in the 2nd half of July cattles were exposed to day-to-day AVG THI above 72 ( 73.59 A± 0.89 ) and to average day-to-day maximal THI above 78 ( 79.09 A± 1.24 ) .
3.3. Energy, protein and mineral metamorphosis.
Plasma metabolites related to energy and protein metamorphosis are shown in Table 2. During the hotter period Se supplementation affected plasma concentrations of NEFA and BHBA, with lower NEFA and greater BHBA concentrations in CTRL animate beings when compared to those supplemented with Se. No important effects were observed for entire cholesterin. During the hotter period a beginning consequence was apparent for NEFA merely, concentrations being higher in SY supplemented animate beings when compared to those supplemented with SS ( Table 2 ) . A negative consequence of THI on glucose and NEFA and a positive consequence on carbamide was observed.
Among plasma minerals merely inorganic Na was affected by Se supplementation during the hotter period ( Table 2 ) . A dose consequence during was observed for inorganic P, but the difference was really little ( 1.93 vs. 1.77 mmol La?’ 1 in cattles fed 0.3 vs. 0.5 milligram entire Se kga?’ 1 DM, severally ) . A negative consequence of THI on plasma Na and K concentration was observed ; conversely, the other minerals were unaffected.
3.4. Acute-phase proteins, oxidative position and enzymes activities
Selenium supplementation did non impact plasma acute stage protein concentrations, and no THI consequence was observed.
Reactive O metabolites ( ROMs ) were non affected by Se supplementation ( Table 3 ) . Reactive O metabolites were positively correlated with +APP, and chiefly with Cp ( r = 0.97 ; P & lt ; 0.001 ) , haptoglobin ( r = 0.52 ; P & lt ; 0.001 ) , and besides globulin ( r = 0.67 ; P & lt ; 0.001 ) . Reactive O metabolites were correlated with SHp ( R = -0.65 ; P & lt ; 0.001 ) merely in SS supplemented cattles. Conversely, ROMs were correlated with GPX-3 ( r = 0.62 ; P & lt ; 0.001 ) and TBARS ( r = 0.42 ; P & lt ; 0.001 ) in both SS and SY supplemented animate beings.
Both beginning ( P & lt ; 0.05 ) and dose ( P & lt ; 0.01 ) effects on TA concentration were observed during the hotter period ( Figure 2 ) , with lower values in cattles supplemented with Se barm when compared to those having selenite addendums ( SY03 vs. SS03 and SS05 vs. SY05 ) and in cattles supplemented with higher doses of Se ( SS05 vs. SS03 and SY05 vs. SY03 ) . Entire antioxidants showed a little, positive correlativity with positive ague stage protein ( +APP ) . However, a important correlativity was observed in SY supplemented cattles ( with Cp: R = 0.35 ; P & lt ; 0.01 ; and besides with globulin: R = 0.30 ; P & lt ; 0.01 ) . Furthermore, in these animate beings, a positive correlativity with ROM ( r = 0.37 ; P & lt ; 0 0.01 ) , and a little negative correlativity with Se position ( entire blood Selenium: R = -0.24 ; P & lt ; 0.05 ; entire plasma Se: R = -0.24 ; P & lt ; 0.05 ) was observed. A little negative correlativity was observed between TA and GPX-1 ( R = -0.22 ; P & lt ; 0.05 ) regardless of intervention or season.
A little dose consequence ( P=0.051 ) was observed for SHp during the hotter period, with lower values in cattles supplemented with 0.31 when compared to those supplemented with 0.50 milligrams entire Se kga?’ 1 DM ( Table 3 ) . A negative consequence of THI on SHp was observed. Thiol groups were chiefly correlated with albumen ( r = 0.68 ; P & lt ; 0.001 ) . In SS supplemented groups SHp was correlated with +APP ( with Cp: R = -0.66 ; P & lt ; 0.001 ; haptoglobin: R = -0.55 ; P & lt ; 0.001 ; and besides with globulin: R = -0.65 ; P & lt ; 0.001 ) and negatively correlated with entire plasma Se ( R = -0.40 ; P & lt ; 0.001 ) and GPX-3 ( R = -0.69 ; P & lt ; 0.001 ) . However these same observations were absent from SY supplemented animate beings.
During the hotter period a beginning consequence was observed for TBARS, with lower values in SY supplemented cattles ( P & lt ; 0.001 ) compared with those supplemented with SS ( Figure 3 ) . Small correlativities were observed between TBARS and +APP irrespective of intervention or season. Conversely, merely in SY supplemented cattles, correlativities between TBARS and indexs of Se position were observed ( entire blood Selenium: R = 0.34 ; P & lt ; 0.01 ; entire plasma Se: R = 0.27 ; P & lt ; 0.05 ; GPX-1: R = 0.40 ; P & lt ; 0.001 ) .
Among enzymes activities merely AST, LDH and plasma glutathione peroxidase ( GPX-3 ) activities were affected by THI ( Table 3 ) , with a positive ( AST and GPX-3 ) and negative ( LDH ) relationship. During the hotter period LDH activity was affected by Se beginning and dosage ( P & lt ; 0.05 ) , with lower values in cattles supplemented with Se barm when compared with animate beings supplemented with selenite, and with higher values in cattles supplemented with the highest degrees of Se supplementation when compared to those having diets supplemented with the lowest degrees of Se supplementation. Plasma glutathione peroxidase ( GPX-3 ) was greater in supplemented cattles ( P & lt ; 0.05 ) , nevertheless, there was no important difference between the two Se beginnings or doses.
3.5. Hematologic response
In general Se supplementation did non impact WBC or leukocyte populations during the hotter period, the exclusion being lymph cells ( Table 4 ) . A beginning consequence was noted during the hotter period on leucocytes count, with lower values of LYM ( P & lt ; 0.05 ) and MON ( P & lt ; 0.05 ) in SY supplemented animate beings when compared with SS supplemented cattles. However, these differences were non evident when each population was expressed as a per centum of WBC ( Table 4 ) . A negative consequence of THI on WBC count and on the per centum of LYM was observed. The NEU and LYM, both as figure and as a per centum of WBC, were significantly correlated ( P & lt ; 0.001 ) with SHp ( R = -0.61, and R = 0.5261, for NEU and LYM per centum of WBC, severally ) . Among the haematological measurings and Se position, merely the basophils were correlated with entire Se of blood and plasma ( r = 0.36, and R = 0.38, severally ; P & lt ; 0.001 ) .
Selenium supplementation did non impact RBC during the test, whereas a important beginning consequence during the hotter period was observed for RDW and PLT ( Table 5 ) .
Cattles of each intervention supplemented with Se showed greater overall mean values ( P & lt ; 0.05 ) of entire Se in blood, plasma, and milk when compared with CTRL animate beings, as highlighted by Calamari et Al. ( 2010 ) . Animals fed the unsupplemented diet ( CTRL ) had mean blood Se concentrations of 163.5 ng ga?’ 1 ( 150.6 to 179.1 nanograms ga?’ 1 ) and average plasma Se concentrations of 72.2 ng ga?’ 1 ( 65.5 to 82 ng g-1 ) , bespeaking marginally equal Se position, if we consider that at least 100 I?g La?’ 1 in whole blood is required to accomplish optimum immune capacity and optimum birthrate ( Stowe and Herdt, 1992 ) . From Silvestre et al. , ( 2007 ) , it can be concluded that good effects of Se supplementation occur merely when the animate beings are Se deficient. In our survey, as antecedently reported by Calamari et Al. ( 2010 ) , average whole blood Se concentrations of CTRL cattles ( 164.3 A± 8.72 ng g-1 ) were in the scope of 150.6 to 179.1 ng g-1, hence easy run intoing the recommendations of Gerloff ( 1992 ) .
Heat emphasis in dairy cattles is considered to be negligible when temperature humidness index ( THI ) values are lower than 72. Index values higher than 72, 78 and 88 reflect the potency for mild, high and terrible degrees of heat emphasis, severally ( Armstrong, 1994 ) . During spring, the average day-to-day THI was below the upper critical value of 72 established for dairy cattles. Valuess of daylight THI recorded during the hotter period were above the upper critical value of 72, bespeaking conditions capable of bring oning moderate heat emphasis ( Armstrong, 1994 ) . Based on these index values, the possible existed in this survey for dairy cattles to endure high heat emphasis for 22 d. These conditions were observed in July and August. During these hotter periods, the day-to-day minimal THI reached values near the minimal value of the zone specifying mild heat emphasis, stand foring mild-moderate heat moving ridges ( Hahn et al. , 1999 ) . In this period, harmonizing to Hahn et Al. ( 1999 ) , two heat moving ridges ( a period of at least 3 back-to-back yearss during which there were less than 10 recovery hours with THI below 72 ) occurred. The first moving ridge was recorded between 16 and 21 of July, with 19 hours where the THI was greater than 79. This five twenty-four hours period was classified as slight-mild heat emphasis. The 2nd moving ridge was recorded between 27 and 29 of July, with 12 hours where the THI was greater than 79, and could be classified as little heat emphasis.
Cattles in the current survey were exposed to a THI above 72 and even over 79 for long periods, but the potency for heat emphasis was mild. The values of all the blood metabolites and enzymatic activities were found to be within the normal mention intervals ( Bertoni et al. , 2000 ) . Measured energy and mineral metamorphosis parametric quantities seem to corroborate that heat emphasis occurred during the hotter period. The negative consequence of THI on plasma glucose observed in the current survey agrees with consequences obtained in heat stressed cattles ( Ronchi et al. , 1997 ; Abeni et al. , 2007 ) . This difference can be explained by different factors: decreased energy consumption, as effect of the decrease in dry affair consumption ; increased cost for thermoregulation ; and negative consequence of the heat on gluconeogenesis, as an endocrinal acclimatization to hot conditions. The negative relationship between THI and NEFA ( Table 2 ) was a farther verification of the metabolic versions to the heat stress status during the hotter period ( Ronchi et al. , 1999 ; Abeni et al. , 2007 ) , proposing increased usage of NEFA as fuel in hepatic and peripheral tissues during heat emphasis ( Ronchi et al. , 1999 ) . The different form of DMI during the dark clip and daylight in the summer season could besides explicate the decrease of NEFA and besides the addition of BHB in plasma from cattles bled before the forenoon repast in hot season ( Ronchi, 1998 ) . In fact there is a meal consequence, with a decrease in NEFA and increase in BHB after a repast ( ASPA Commission, 1999 ) . Refering the mineral metamorphosis parametric quantities, the negative consequence of THI on plasma Na and K concentration observed in the current survey agrees with the consequences obtained by Ronchi et Al. ( 1995 ) in calves exposed to really high temperatures.
During terrible heat emphasis the decrease in enteric blood flow can arouse an inflammatory response ( Lambert, 2009 ) , ensuing in the publicity of the synthesis of +APP, and as a effect the decrease of several indispensable proteins ( including albumens ) called negative ague stage proteins ( -APP ) . In the current survey the APP were non affected by THI, corroborating that cattles were non exposed to severe heat emphasis. Furthermore, these APP were non affected by Se supplementation.
Among the plasma markers of oxidative position, the negative relationship between THI and SHp could be a effect of increased plasma protein oxidization ( Sandre et al. , 2004 ) . Increases in AST activity indicate a little damage of tissues, and besides this consequence could be a effect of an oxidative consequence. However, the values of LDH activity, and the activity of other enzymes related to weave damage, falls within scope and are really near to values observed by Juniper et Al. ( 2008 ) . Therefore, these consequences seem to bespeak that a general damage of tissues was non apparent. Among the other markers of oxidative position, ROM were non affected by THI, however the positive consequence of THI on GPX-3 could be interpreted as an up-regulation in stress conditions. Indeed, GPX is good regulated and its increased activity can be considered an extra protective mechanism in stress conditions ( Surai, 2006 ) .
The plasma TBARS concentrations in the current survey were greater than the values obtained with the fluorimetric method ( Mudron et al. , 2007 ) and lower than values observed by Bernabucci et Al. ( 2002 ) in early lactating cattles. The TBARS were non affected by THI, however, during the hotter period important differences were observed. The lower TBARS values in SY cattles compared with SS cattles could be related to lower oxygen-free extremist values, sing that lipoids are a possible mark for the latter, in the procedure of lipid peroxidation and production of lipoperoxides ( increasing TBARS ) and impaired membrane unity. Cytotoxic aldehydes ( e.g. , malonaldehyde ) that remain after expiration of lipid peroxidation provide the footing for the TBARS trial in organic structure fluids. ( Miller et al. , 1993 ) .
Oxidative emphasis ensuing from increased production of free groups and reactive O species, and/or a lessening in antioxidant defence, leads to damage of biological supermolecules and break of normal metamorphosis and physiology ( Trevisan et al. , 2001 ) . In the current survey no beginning consequence was observed on whole blood GPX ( Calamari et al. , 2010 ) and on plasma GPX. Besides the SHp ‘s were non affected by Se beginning. However, different relationships between SHp and indexs of Se position were observed between animate beings supplemented with SY when compared to those supplemented with SS. Furthermore, differences were besides observed in the relationship between SHp and ROM in SY when compared to SS supplemented animate beings. Different hypothesis could be formulated to explicate these different consequences obtained with SS and SY.
Selenite is capable of advancing extremist formation and oxidative emphasis through its reaction with decreased glutathione ( Surai, 2006 ) , demobilizing critical thiol-containing enzymes by oxidization and bring forthing ROM. It has been observed that selenite generates ROM and causes cellular harm in the presence of sulfhydril compounds ( Surai, 2006 ) . Conversely, selenomethionine and Se-methylselenocysteine are non oxidising agents ( Drake, 2006 ) . In most experiments SeMet was non able to bring forth ROM when added into an incubation medium in combination with decreased glutathione ( Surai, 2006 ) . These findings contribute to explicate the negative correlativity between SHp and entire plasma Se observed merely in cattles supplemented SS. Furthermore, these findings besides contribute to explicate the negative correlativity between ROM and SHp observed merely in cattles supplemented SS.
The inactivation of critical thiol-containing enzymes by oxidization reduces the activity of the first group of endogenous antioxidants ( including GPX ) . The care of glutathione reductase activity ( Mahmoud et al. , 2003 ) enhances and facilitates the ability to cut down oxidized glutathione ( GSSG to 2 GSH ) . A thiol oxidation-reduction system, dwelling of the glutathione and thioredoxin systems, is believed to be the major participant of the oxidation-reduction position of the cells ( Surai, 2006 ) . Thioredoxin reductase, a selenoenzyme ( Surai, 2006 ) , can cut down non merely thioredoxin, but besides oxidized glutathione ( Surai 2006 ) . Rousseau et Al. ( 2006 ) observed higher blood oxidized glutathione and lower SHp in exercised aged topics when compared with exercised immature topics. In the current survey, blood oxidized glutathione was non measured, however, the different relationships between SHp and with the indexs of Se position and plasma ROM seem to bespeak a less marked damage of the 2nd group of the endogenous antioxidants ( SHp ) in SY instead than in SS supplemented animate beings. This consequently consequences in the damage of the first group of endogenous antioxidants, including GPX.
Castillo et Al. ( 2006 ) suggested that decreased serum TA is non needfully an unwanted status when the production of reactive species ( which would be reflected in malonaldehyde values, as observed in this survey in SY cattles ) decreases. The lower plasma TA in cattles fed SY in the current survey could be interpreted as an betterment in their preventative antioxidant systems in footings of the free extremist formation and chain-breaking antioxidants. Despite GPX-1 activities non differing between SY and SS supplemented animate beings ( Calamari et al. , 2010 ) , the differences observed between the markers of oxidative position with Se position seem to bespeak that SY improves the bar of free extremist formation, with a attendant decrease in plasma TA. Because Se ( glutathione and thioredoxin systems ) is besides involved in the line of defence consisting of chain-breaking antioxidants ( Surai, 2006 ) , it could be hypothesized that the decrease in plasma TA could be a effect of an betterment in the chain-breaking antioxidants non detected with the analysis of TA in plasma ( i.e. , intracellular systems as phospholipid hydroperoxide GPX or GPX-4 and thioredoxin system ) . Furthermore, these reduced systems lessening oxidized glutathione, and so better the activity of GPX. However, farther surveies are needed to corroborate these hypotheses.
The values for haematological profiles were found to be within normal mention intervals for dairy cattles in the environment of this survey ( Archetti and Ravarotto, 2002 ) . The negative consequence of THI on go arounding WBC and of each leukocyte population agrees with the consequences of Paape et Al. ( 1973 ) , when a regular alternation between hot yearss and cooler darks take topographic point. The lower values of PLT in SY groups during the hotter period did non hold with the consequences of Sakr et Al ( 2007 ) on the relationship between PLT count and plasma Se. In fact, they reported a positive correlativity between these two characteristics, but in the current test the SY groups, characterized by low PLT during the hotter period, are the same with higher plasma Se ( Calamari et al. , 2010 ) .
The temperatures and humidness recorded during this test indicated that cows in this survey may hold suffered slight-mild heat emphasis during the hotter period, as highlighted by microclimatic status every bit good as by the carnal response ( i.e. alterations in plasma glucose, NEFA and electrolytes ) . The low Se supplementation in CTRL cattles, every bit good as the entire Se in whole blood and plasma, indicate a marginally equal Se position in these animate beings. This was confirmed by the deficiency of of import effects on haematological profiles, by and large more antiphonal when Se is lacking. Oxidative emphasis, with greater plasma TBARS, during the hotter period was observed in CTRL animate beings compared to those observed in cow fed SY. Furthermore, during the hotter period, cows fed SY, when compared to those fed SS have shown lower plasma TBARS and plasma sum antioxidant, every bit good as numerically lower plasma ROM. These consequences could be interpreted as an betterment in the preventative antioxidant systems in footings of the bar system of free extremist formation and concatenation breakage antioxidants in cattles fed Se barm, with a lower lipid peroxidation during hotter periods, when animate beings are subjected more to oxidative emphasis.