To assess growth promoting agents efficacy among seasons, triiodothyronine, thyroxine, blood metabolites, and tympanic temperature were measured in summer and winter studies. Within each season, pens of heifers were assigned to one of six growth promotant treatments. Season by growth promotant treatment interactions (P \u3c 0.05) indicated that the combination of estrogen and trenbolone acetate increased triiodothyronine in the winter, whereas trenbolone acetate alone decreased both triiodothyronine and thyroxine in the winter. Maximum tympanic temperature was greater (P \u3c 0.01) in the summer than in the winter, while minimum tympanic temperature was lowered (P \u3c 0.01) in the summer. Changes in blood metabolite levels resulting from the use of growth promotants do not appear to substantially influence seasonal changes in body temperature

Kreikemeier, Wanda

Mader, Terry L.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Nebraska Beef Cattle Reports Animal Science Department January 2006 Growth Promoting Agents and Season Effects on Blood Metabolite and Body Temperature Measures Terry L. Mader University of Nebraska-Lincoln, tmader1@unl.edu Wanda Kreikemeier Northeast Research and Extension Center, Concord Follow this and additional works at: https://digitalcommons.unl.edu/animalscinbcr  Part of the Animal Sciences Commons Mader, Terry L. and Kreikemeier, Wanda, "Growth Promoting Agents and Season Effects on Blood Metabolite and Body Temperature Measures" (2006). Nebraska Beef Cattle Reports. 130. https://digitalcommons.unl.edu/animalscinbcr/130 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Nebraska Beef Cattle Reports by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. © 2005, The Board of Regents of the University of Nebraska.  All rights reserved. 2006 Nebraska Beef Report  — Page 79 Growth Promoting Agents and Season Effects on BloodMetabolite and Body Temperature MeasuresTerry L. MaderWanda M. Kreikemeier1SummaryTo assess growth promoting agents efficacy among seasons, triiodothyro-nine, thyroxine, blood metabolites, and tympanic temperature were measured in summer and winter studies. Within each season, pens of heifers were assigned to one of six growth promotant treatments. Season by growth promotant treatment interactions (P  < 0.05) indicated that the combination of estrogen and trenbo-lone acetate increased triiodothyronine in the winter, whereas trenbolone ace-tate alone decreased both triiodothy-ronine and thyroxine in the winter. Maximum tympanic temperature was greater (P  < 0.01) in the summer than in the winter, while minimum tympanic temperature was lowered (P  < 0.01) in the summer. Changes in blood metab-olite levels resulting from the use of growth promotants do not appear to substantially influence seasonal changes in body temperature.IntroductionWithin a season, changes in tem-perature, wind speed, precipitation, and/or radiation can significantly influence physiological and metabolic processes. Physiological character-istics, particularly when cattle are under environmental stress, could be further influenced by anabolic agents. The objective of this experiment was to assess feedlot heifer responses to cold and heat exposure when admin-istered growth promoting agents as determined by blood endocrine levels, plasma urea nitrogen (PUN), and tympanic temperature.ProcedureDuring a summer and winter sea-son, crossbred Angus, nonpregnant, yearling heifers (108/season; mean initial BW = 842 lb) were used for obtaining blood samples and tym-panic temperatures (TT). Within a season, heifers had been stepped up to a 65.0 NEg (mcal/cwt; DM basis) high-energy finishing diet by the start of each study. Heifers were fed Rumensin and Tylan (Elanco Animal Health, Indianapolis, Ind.) through-out the experimental feeding period. Details of the vaccination, parasite control, and diet regimens used for the experiments have been reported previously (2003 Nebraska Beef Report, pp. 42-45). In early December (winter season), and early June (summer sea-son), heifers were assigned randomly to 12 pens (nine heifers/pen) based on stratification of individual weights. Six growth promotant treatments (two pens of heifers/treatment/season) were imposed as follows: 1) control, 2) estrogenic implant (E; Compudose [24 mg of Estradiol-17β]; Vetlife, West Des Moines, Iowa), 3) androgenic implant (TBA; Finaplix-H [200 mg of trenbolone acetate]; Intervet, Inc., Millsboro, Del.), 4) E + TBA (ET), 5) no implant and fed MGA (MGA; Pharmacia and Upjohn, Kalamazoo, Mich.), and 6) ET implant and fed MGA (ETM). Heifers were bled via jugular puncture and weighed on days 0, 28, 56, and 84. Cattle were fed 104 and 105 days for the winter and sum-mer feeding periods, respectively.Blood Collection and AssaysIn both seasons, heifers (four/pen) were bled via jugular puncture and weights were taken on days 0, 28, 56, and 84, beginning at 0800 and prior to being fed. Ten milliliters of blood for plasma were collected into tubes containing sodium heparin. Five milli-liters of blood also were collected for serum. After blood collection, tubes were centrifuged (3,400 rpm) for 10 minutes. Plasma and serum frac-tions were isolated and frozen until analyzed. Serum samples were ana-lyzed for insulin-like growth factor (IGF-1) concentration using RIA with acidBethanol extraction. Concentra-tions of thyroxine (T4), triiodothyro-nine (T3) were quantified with solid phase RIA kits. Samples for T3 and T4 analysis were processed as separate assays. Temperature measuresIndividual heifers (two heifers/pen; four heifers/treatment/season) were used for obtaining TT, as a measure of body temperature, when ambient temperature was predicted to be  < 32oF in the winter and > 77oF in the summer. Tympanic temperatures were recorded using data loggers and thermistor cables (Stowaway, XTI7, Onset Computer Corporation, Pocassatt, Mass.). Data loggers were secured in an ear of the heifer using self-adhesive bandages (Vet-Wrap7, 3M Corporation, St. Paul, Minn.) and 2.25 cm athletic tape (Andover Coded Products Inc, Salisbury, Mass.). Tym-panic temperature was read every two minutes, with the average recorded every 15 minutes over a seven and five-day period for winter and sum-mer, respectively. On day 28 of each study period, at the time of weighing, ear surface temperature was measured on four heifers from each pen using a Raynger 3i infrared gun (Raytek Cor-poration, Santa Cruz, Calif.).Statistical AnalysisBlood metabolite concentrations were analyzed using Mixed Models procedures of SAS (SAS Inst. Inc., Cary, N.C.) for a split plot in time design. The model included season, growth promotant treatment, and day (used as repeated measures) plus two and three-way interaction. Unstruc-tured covariance analysis was used for T3, T4, and PUN, while auto regressive (Continued on next page)Page 80 — 2006 Nebraska Beef Report  © 2005, The Board of Regents of the University of Nebraska.  All rights reserved.procedures were used in the IGF-1 analysis. Tympanic temperature and ear surface temperature data were analyzed using Mixed Models pro-cedures of SAS for a completely ran-domized design. Least squares means were compared using an F-protected LSD (P  < 0.05). ResultsFor the hot and cold periods, dur-ing which TT were obtained, ambi-ent temperature averaged 80.1 and 26.8oF, respectively, and ranged from a daily average of 63.5 to 94.8oF for the hot period, and 2.5 to 51.8 for the cold period. Mean THI [temperature humidity index; THI = temperature B (0.55*(1-rh/100)*(temperature B 58))] was 76.6 for the hot period and 17.4 for the cold period. Based on the livestock safety index, heifers exposed to hot conditions were on the average in the alert (THI > 74) category, but also also exposed to emergency (THI > 83) category conditions, suggesting cattle were under heat stress during most of this period. During the cold TT collection period, THI ranged between 1.6 and 36.8. A THI < 35 has been suggested as being a cold stress threshold; clearly this threshold was reached. In general, IGF-1 increased  (P  < 0.05) from day 0 to day 28 in  the winter and in the summer (Table 1). However, IGF-1 levels declined  (P  < 0.05) after day 28 in the winter but tended to be maintained at day 28 levels throughout the summer. Thy-roid hormone levels (T3 and T4) fol-lowed similar trends among seasons across bleed times. As expected, T3 and T4 levels were numerically elevat-ed in the winter compared with the summer, but were very similar among season on day 84. In general, by day 84, ambient temperatures were declin-ing in the summer, thus stimulating thyroid gland activity, and increasing in the winter which suppresses thy-roid gland activity. On day 56, PUN was elevated in the winter and low-ered in the summer when compared with day 28 (P  < 0.05); thus PUN tended to peak around day 56 in the Table 1. Mean blood PUN and endocrine concentration for feedlot heifers for season and time of bleed. Day of bleedbItema 0 28 56 84 SEIGF B 1, ng/mLWinter 98.42cde 129.03f 101.78de 90.64c 5.83Summer 59.50c 104.64ef 95.43de 109.33f 5.83T3, ng/mLWinter 1.44c 1.48c 1.61d 1.46c 0.05Summer 1.19d 0.94c 0.96c 1.34e 0.05T4, ng/mLWinter 66.12c 68.03c 77.65d 68.52c 1.95Summer 66.65de 53.57c 63.29d 68.33e 1.95PUN, mg/dLWinter 9.62c 13.50e 19.13f 12.19d 0.54Summer 13.69d 17.66e 13.11d 11.60c 0.54aT3 = triiodothyronine; T4= thyroxine; PUN = plasma urea nitrogen.bNumber of days into trial. Day by season interaction (P  < 0.05) for all metabolites.cdefMeans without a common superscript differ (P  < 0.05).Table 2. Effects of growth promoting treatment and season on blood metabolite concentration.  Growth promoting treatmentbItema C E TBA ET MGA ETM SEIGF B 1, ng/mlWinter 97.72 109.70 100.69 116.10 92.48 118.10 11.38Summer 80.70 90.62 92.49 97.55 82.50 109.48 11.38Mean 86.71c 100.16cd 96.59cd 106.82d 87.49c 113.79d 7.79T3, ng/mleWinter 1.49f 1.44f 1.33f 1.72g 1.51fg 1.50f 0.07Summer 1.17 1.20 1.14 1.02 1.06 1.05 0.07Mean 1.33 1.32 1.23 1.37 1.29 1.28 0.05T4, ng/mlWinter 69.06 70.02 65.01 70.57 67.67 78.05 3.21Summer 59.77 62.49 62.93 63.01 67.22 62.34 3.21Mean  64.42 66.26 64.02 66.80 67.44 70.19 2.80PUN, mg/dlWinter 13.70 14.87 12.91 12.05 15.12 13.00 0.73Summer 14.91 15.11 15.12 12.84 14.04 12.08 0.73Mean 14.30g 14.99g 14.01g 12.44f 14.58g 12.54f 0.49 aT3 = triiodothyronine; T4= thyroxine; PUN = plasma urea nitrogen.bC = Control (no growth promotant), E = estrogenic implant, TBA = trenbolone acetate implant, ET = estrogenic + TBA, MGA = melengestrol acetate, ETM = E + TBA + MGA.cdMeans without a common superscript differ (P  < 0.10).eGrowth promoting treatment by season interaction (P  < 0.05).fgMeans without a common superscript differ (P  < 0.05).winter and day 28 in the summer.In these studies, season x growth promotant interactions were not found (P  > 0.05) for ADG, although ADG was greater (P  < 0.01; 3.18 vs 2.80 lb) in the winter than in the summer (2003 Nebraska Beef Report, pp. 42-45). In data reported herein, serum IGF-1 concentrations increased (P  < 0.05) by ~ 43% from day 0 to 28 in the summer but by only 24% in the winter. Also in the winter, IGF-1 levels declined by ~ 21% from day 28 to 56, thus returning to near levels found on day 0. In the summer, IGF-1 levels only declined by ~ 9% (P  > 0.05) from day 28 to 56 and remained above (P  < 0.05) day 0 level through day 84. Since baseline IGF-1 (98.4 vs 59.5 mg/mL) were greater in the winter, dif-ferences in ADG are not likely due to the rise or change in IGF-1 over time or among seasons, but partially due to the baseline IGF-1 level associated with the cattle at the start of the study. Also, in the winter, during the period when ambient temperatures decline and approach winter lows, feed intake © 2005, The Board of Regents of the University of Nebraska.  All rights reserved. 2006 Nebraska Beef Report  — Page 81 concentration. The ET treated heif-ers had increased (P  < 0.05) T3 levels in the winter when compared with control and other implanted heifers. Across season, heifers receiving ET (ET and ETM treatments) had lower PUN levels.A bleed time by growth promotant treatment interaction was not found for thyroid hormones but was found (P  < 0.05) for IGF-1 and PUN (Table 3). In general, when compared with control heifer groups, ET and ETM treated heifers had greater (P  < 0.05) IGF-1 concentrations on day 28, whereas the ETM and TBA treated cattle had greater IGF-1 concentra-tions on day 56; only the ETM treated heifers had greater IGF-1 concentra-tions on day 84. Thus, the ETM treated cattle had consistently greater IGF-1 concentration during the feed-ing period, which is supported by the tendency (P  < 0.10) for those same heifers plus the ET treated group to have lower PUN concentrations (days 28 and 56) than the control heifer group.Ear surface temperatures were 92.3oF and 56.5oF (P < 0.01), respec-tively for summer and winter (Table 4). The ear surface temperatures were recorded in the event growth-promoting agent by season inter-actions could be attributable to payout of the implant. Average tym-panic temperature was not different (P  > 0.05) between seasons. A greater range in TT was found in the sum-mer than in the winter. Maximum TT was greater (P  < 0.01) and minimum TT was lower (P  < 0.01) in the sum-mer than in the winter. Analysis of hourly data (Figure 1) indicate that peak summer TT occurs around 1700 while peaks in winter TT are not as evident. Also, minimum summer TT were found at 0700. Difference in TT between summer and winter were found at 0500, 0600, 0700, 0800, 1600, 1700, and 2100 with the diurnal TT pattern being flatter in the winter than in the summer.There was a growth promoting treatment by season interaction  (P  < 0.05) for ear surface temperature Table 3. Effects of growth promoting treatment and time of bleed on IGF-1 and plasma urea nitrogen (PUN) concentrations in feedlot heifers. Growth promoting treatmentaItema C E TBA ET MGA ETM SEIGF B 1, ng/ml 0 day 73.72 76.85 67.74 90.05 85.26 80.13 10.45 28 days 104.72bc 121.01cd 114.09bcd 135.11d 93.67b 132.39d 10.45 56 days 79.25b 93.47bc 113.14c 100.71bc 86.41b 118.64c 10.45 84 days 89.16b 109.31bc 91.39b 101.43bc 84.61b 124.01c 10.45 PUN, mg/dl 0 day 11.09 12.34 11.35 11.37 12.56 11.21 0.97   28 days 16.99g 17.35g 15.75fg 12.58e 17.18g 13.60ef 0.97 56 days 17.18g 18.06g 16.39fg 14.45ef 16.44g 14.20e 0.97   84 days 11.95 12.20 12.57 11.37 12.12 11.15 0.97aC = Control (no growth promotant), E = estrogenic implant, TBA = trenbolone acetate implant, ET = estrogenic + TBA, MGA = melengestrol acetate, ETM = E + TBA + MGA. Day by growth promoting treatment interaction (P  < 0.05).bcdMeans without a common superscript differ (P  < 0.05).efgMeans without a common superscript differ (P  < 0.10).Table 4. Effect of season on tympanic (TT) and ear surface (EST) temperature. SeasonItem Summer Winter SEEST, oF 92.26b 56.48a 0.22TT, mean, oF 102.27 101.97 0.15Maximum, oF 104.07b 102.97a 0.05Minimum, oF 100.20a 101.05b 0.04abMeans without a common superscript differ (P  < 0.01).is stimulated which resulted in greater PUN levels that were found on day 56. In the summer, ambient temperature would be peaking around day 56, thus suppressing feed intake resulting in blood PUN being lowered. This de-cline in summer PUN levels could be due to the decrease in DMI. There was no (P  > 0.05) growth promoting agent by season interaction for serum IGF-1, T4, or PUN concen-tration (Table 2). Across both seasons, IGF-1 tended to be increased (P  < 0.10) in ET and ETM treated heifers when compared with control heifers. No differences in T4 were observed among growth promotant treatments within or among season. There was a growth promoting treatment by season interaction (P  < 0.05) for T3 (Continued on next page)080009001000110012001300140015001600170018001900200021002200230024000100 0200 0300 0400 0500 0600 0700Figure 1. Effects of season on tympanic temperature over a 24-hour period. *Means differ (P  < 0.05; SE = 0.18).103.5103102.5102101.5101100.5100Tympanic temperatureWinter SummerHourPage 82 — 2006 Nebraska Beef Report  © 2005, The Board of Regents of the University of Nebraska.  All rights reserved.(Table 5). In the summer, there was no difference between ear surface temperatures across growth promot-ing treatments while in the winter, the MGA treated heifers had ear surface temperatures similar to control but lower (P  < 0.05; 51.1 vs 58.5 1F) than groups receiving implants. These data suggest that, at least in the winter, implanting can elevate ear surface temperatures as much as 101F, how-ever, overall ear surface temperatures in the winter are over 36oF lower than those found in the summer.A growth promoting treatment by season interaction was evident for average maximum TT (P  < 0.05)  and for average minimum TT  (P  < 0.10), although the interaction was not evident for mean TT (Table 5 and Figure 1). Mean TT were similar among growth promotant treatment among seasons. Numerically, control heifer groups had greater maximum TT, particularly in the winter, with the MGA heifers having the lowest maximum TT in both seasons. The ET treated cattle had greater (P  < 0.05) maximum TT in the summer when compared with MGA fed groups (MGA and ETM). However, in the winter, cattle receiving E and/or MGA (E, ET, MGA, and ETM) had lower maximum TT than control cattle. Differences in minimum TT tended to be found only in the summer, with E treated cattle having greater mini-mum TT than TBA and ETM treat-ment groups.The data indicate that when cattle get hot in the summer, they tend to overcompensate at night by ridding the body of heat (resulting in a lower TT) in preparation for subsequent heat episodes. Thus, the range in TT will be greater in the summer than in the winter. The lower night-time TT appears to enable cattle to prepare for the heat of the day, while greater overall TT in the winter buf-fers the animal against cold threats. The greater minimum TT found in the E treatment group in the summer would suggest E implanted cattle may be more susceptible to heat stress. If E increases TT, the mechanism by which MGA tends to lower TT is unclear, since the growth promoting response of both products are medi-Table 5. Effect of growth promoting treatment and season on tympanic temperature (TT) and ear surface temperature (EST). Growth promoting treatmentaItem C E TBA ET MGA ETM SEEST, oFb  Winter 54.50cd 55.58d 56.48d 59.18d 51.08c 62.24d 0.53 Summer 92.66 92.84 91.04 92.48 93.20 91.40 0.53 Mean 73.58 74.30 73.76 75.92 72.14 76.82 0.33Mean TT, oF Winter 102.63 101.79 100.53 101.64 101.59 101.97 0.37 Summer 102.15 102.25 102.09 103.46 102.85 101.75 0.37 Mean 102.40 102.02 102.18 102.56 102.22 101.86 0.24Maximum TT, oFb Winter 104.14d 102.65c 103.14cd 102.45c 102.43c 102.99c 0.17   Summer 104.41de 103.95cde 104.32de 104.79e 103.50c 103.64cd 0.17 Mean 104.29d 103.30c 103.64cd 103.62cd 102.97c 103.32c 0.08Minimum TT, oFb Winter 101.12 100.98 101.23 100.98 100.74 101.26 0.15 Summer 99.84f 100.98g 99.82f 100.31fg 100.44fg 99.72f 0.15 Mean 100.49 100.98 100.53 100.65 100.60 100.49 0.07aC = Control (no growth promotant), E = estrogenic implant, TBA = trenbolone acetate implant, ET = E + TBA, MGA = melengestrol acetate, ETM = E + TBA + MGA.bGrowth promotant by climatic condition interaction (P  < 0.10).cdeMeans without a common superscript differ (P  < 0.05).fghMeans without a common superscript differ (P  < 0.10).ated through estrogen receptors. The estrus suppressing effect of MGA, which is not present in implants, is possibly responsible for any lowering of TT particularly in the ETM group. However, control heifers had greater overall maximum TT. Although limited growth promotant by season interactions existed, changes in blood metabolite levels resulting from the use of growth promotants do not appear to substantially influence sea-sonal changes in body temperature.1Terry Mader, professor; Wanda Kreike-meier, former graduate student, Department of Animal Science, Northeast Research and Exten-sion Center, Concord.

Growth Promoting Agents and Season Effects on Blood Metabolite and Body Temperature Measures

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Growth Promoting Agents and Season Effects on Blood Metabolite and Body Temperature Measures

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