Effects of growth-promoting agents and season on blood metabolites and body temperature in heifers1,2

Mader, Terry L.; Kreikemeier, W. M.

doi:10.2527/2006.8441030x

Cited by 30 publications

(21 citation statements)

References 24 publications

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“…Considering the greater ADG and G:F observed in implanted heifers, one would expect that they utilized N better than control heifers. Supporting the present study, previous research indicated that heifers implanted with estradiol+trenbolone acetate had reduced plasma urea N compared to non-implanted controls or heifers implanted with either estradiol or trenbolone acetate alone (Mader & Kreikemeier, 2006). On the other hand, Cheatham (2005) indicated that SUN did not differ between implanted and non-implanted Holstein steers.…”

Section: Resultssupporting

confidence: 74%

“…This agrees with many previous reports indicating that implanting steers increases circulating IGF-1 (Lee & Henricks, 1990;Hunt et al, 1991;Cheatham, 2005). Furthermore, Mader & Kreikemeier (2006) found IGF-1 concentrations to be greater in estradiol+trenbolone acetate implanted heifers compared to controls, but found no differences in IGF-1 between controls and those animals implanted only with estradiol or trenbolone acetate. Moreover, serum IGF-1 is generally considered to be a GH dependent peptide (Florini et al, 1991).…”

Section: Resultsmentioning

confidence: 99%

“…However, the physiological and molecular explanation for this performance recovery, via implantation is poorly understood. Vestergaard et al (1995) found that ovariectomy did not affect circulating insulin like growth factor -1 (IGF-1) in unimplanted Holstein heifers, and Mader & Kreikemeier (2006) found IGF-1 concentrations to be greater in estradiol + trenbolone acetate (TBA) implanted heifers compared with unimplanted heifers, but found no differences in IGF-1 concentrations between controls and those animals implanted only with estradiol or TBA. However, TBA alone or implanted synergistically with an oestrogenic implant had no effect on growth hormone (GH; Hunt et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

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Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers

Bailey¹,

Duff²,

Sanders³

et al. 2008

SA J. An. Sci.

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________________________________________________________________________________ AbstractA 2 x 2 factorial experimental design was used to evaluate effects of ovariectomy and implantation (200 mg trenbolone acetate and 28 mg estradiol benzoate; Synovex-Plus) on the performance, serum urea nitrogen, serum insulin like growth factor -1 (IGF-1), and mRNA expression of hepatic IGF-1, growth hormone (GH) receptor and estrogen receptor-α as well as pituitary GH, estrogen receptor-α and GH releasing hormone receptor in feedlot heifers. Thirty-two British x Continental heifers were randomly assigned to either an ovariectomized (OVX) or intact group and then to either a control group or a SynovexPlus implant group. Heifers were fed a 900 g/kg concentrate steam-flaked maize based diet for 42 d. Liver biopsies were taken before OVX for baseline expression of IGF-1, GH receptor and hepatic estrogen receptor-α, which did not differ between treatment groups. Blood and body weight (BW) were taken on d 0, 28, and 42 and one heifer/pen was slaughtered on d 42 for liver and pituitary tissue samples. Initial and final BW did not differ due to OVX or implant. No gender x treatment interaction was observed for average daily gain (ADG) or final BW. Neither OVX nor implant affected ADG for the final 14 d of the feeding period, but 28 and 42 d ADG were greater in implanted than in control heifers. No 2-or 3-way interactions with day were observed for serum urea nitrogen. Serum urea nitrogen was greater in control heifers than in implanted heifers, but gender had no effect. Both implant and OVX increased serum IGF-1 and a gender x treatment interaction was observed. Neither gender nor implant treatment affected hepatic estrogen receptor-α, hepatic IGF-1, hepatic GH receptor, GH releasing hormone receptor, GH, or pituitary estrogen receptor-α. Data indicate that implanting heifers with Synovex-plus increases serum IGF-1, but the reason for this increase cannot be explained by mRNA expression of key somatotropic genes in the present study.________________________________________________________________________________

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Section: Resultssupporting

confidence: 74%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers

Bailey¹,

Duff²,

Sanders³

et al. 2008

SA J. An. Sci.

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“…Other studies in controlled laboratory environments have made precise measurements of thermoregulatory effector response to heat stress but only over a period of several hours. Only recently have studies begun to make detailed measurements in the field over a period of time representative of normal exposure during the summer (Lefcourt and Adams 1996;BrownBrandl et al 2005a;Eigenberg et al 2005;Mader and Kreikemeier 2006;Gaughan et al 2008;Arias and Mader 2009). Current measurements include air (T a ) and black globe (T bg ) temperatures, temperature humidity index (THI), which combines T a and percent relative humidity (%RH), and the modified Black Globe Temperature Humidity Index (BGTHI), which utilizes T bg in place of T a .…”

Section: Introductionmentioning

confidence: 99%

Determinants of bovine thermal response to heat and solar radiation exposures in a field environment

et al. 2010

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Continuous exposure of cattle to summer heat in the absence of shade results in significant hyperthermia and impairs growth and general health. Reliable predictors of heat strain are needed to identify this condition. A 12-day study was conducted during a moderate summer heat period using 12 Angus x Simmental (Bos taurus) steers (533± 12 kg average body weight) to identify animal and ambient determinations of core body temperature (T core ) and respiration rate (RR) responses to heat stress. Steers were provided standard diet and water ad libitum, and implanted intraperitoneally with telemetric transmitters to monitor T core hourly. Visual count of flank movement at 0800 and 1500 hours was used for RR. Dataloggers recorded air temperature (T a ), and black globe temperatures (T bg ) hourly to assess radiant heat load. Analysis was across four periods and 2 consecutive days averaged within each period. Average T a and T bg increased progressively from 21.7 to 30.3°C and 25.3 to 34.0°C, respectively, from the first to fourth periods. A model utilizing a quadratic function of T a explained the most variation in T core (R 2 =0.56). A delay in response from 1 to 3 h did not significantly improve R 2 for this relationship. Measurements at 0800 and 1500 hours alone are sufficient to predict heat strain. Daily minimum core body temperature and initial 2-h rise in T a were predictors of maximum core temperature and RR. Further studies using continuous monitoring are needed to expand prediction of heat stress impact under different conditions.

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“…There is evidence that estrogenic compounds increase plasma concentration of T 4 (Trenkle, 1997). Also, implants based in estrogenic substances and trembolone acetate appear to enhance the normal thyroid activity (Mader and Kreikemeier, 2006). In the present study, Synovex implants were used.…”

Section: Resultsmentioning

confidence: 99%

Artificial cooling as an alternative to increase productivity and welfare of steers under heat stress

Correa‐Calderón

Jiménez

Avendaño

et al. 2010

Arq. Bras. Med. Vet. Zootec.

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The effects of a cooling system on productive efficiency and welfare of Holstein steers were evaluated during the summer. Sixty steers in the finishing phase were randomly allotted to one of two treatment-groups. Animals of control group were only provided with shade (non-cooled group) and a group of animals under a cooling system were installed in the shaded area (cooled group), which were operated daily from 09am to 6pm during the 69d of the study. The averages of environmental temperature and relative humidity were 35.4°C and 35.3%, respectively, with a temperature-humidity index average of 81.4 during the study. Individual body weight was recorded every two weeks, while body surface temperature and respiratory frequency were recorded three times per week. Blood samples were biweekly taken from coccygeal vein for determination of T 3 and T 4 . The average daily gain in the cooled group gain (1.46kg/d) was similar (P=0.21) to non-cooled group (1.37kg/d). Body surface temperature (35.9ºC vs 38.7ºC) and respiratory frequency per minute (77 vs 104) were lower (P<0.01) in the cooled group than in non-cooled group, respectively. Triiodotironine levels were similar (P=0.30) in cooled (0.80ng/mL) and non-cooled (0.87ng/mL) groups, while, tiroxine level was lower (P<0.01) in cooled group (44.0ng/mL) compared to non-cooled group (56.6ng/mL). The cooling system did not improve productive parameters but the welfare in the cooled group was increased.

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Effects of growth-promoting agents and season on blood metabolites and body temperature in heifers1,2

Cited by 30 publications

References 24 publications

Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers

Effects of ovariectomy and anabolic steroid implantation on the somatotrophic axis in feedlot heifers

Determinants of bovine thermal response to heat and solar radiation exposures in a field environment

Artificial cooling as an alternative to increase productivity and welfare of steers under heat stress

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