Biomedical subjects

R D Randel

Publications and source records attributed to R D Randel.

At least 73 records · Page 4Linked to original sources

PubMed1995

Effects of free gossypol in the diet of pregnant and postpartum Brahman cows on calf development and cow performance.

Pregnant Brahman cows (n = 38) and heifers (n = 12) were assigned, 90 d before expected calving dates, to one of three treatment groups: 1) 0 g of free gossypol(FG).animal-1.d-1 (FGHD) from soybean meal (SBM), controls; 2) 2 g of FGHD from SBM and cottonseed meal (CSM), low FG; or 3) 4 g of FGHD from CSM, high FG, to determine the effects of dietary FG on prepartum and postpartum cow performance, calf development, and selected blood variables. Prepartum and postpartum cow BW, 4-h milk production, and calf BW were similar (P > .10) among treatments. Following 84 d of treatment, cows receiving 4 g of FGHD tended (P < .10) to have greater erythrocyte fragility (EF) than cows given 0 or 2 g of FGHD. Mean EF for the 112-d postpartum period were greater (P < .05) in cows given 4 than in those given 0 g of FGHD. Dietary FG consumption by the dam did not affect (P > .10) calf EF. Serum triiodothyronine (T3) and thyroxine (T4) in cows and T4:T3 ratio in calves were similar (P > .10) among treatments. After 84 d of treatment, cows receiving 4 g of FGHD had lower (P < .05) serum concentrations of alpha-tocopherol and beta-carotene than cows given 0 g of FGHD. At parturition, serum alpha-tocopherol and beta-carotene were similar (P > .10) for all cows and calves. On d 7 and 28 after calving, alpha-tocopherol tended to be lower (P < .10) and beta-carotene was lower (P < .05) in calves given 4 than in those given 0 g of FGHD. Calf metacarpal medial cortex tended to be greater (P < .10) in calves from cows given 0 than in those from cows given 2 or 4 g of FGHD, and the lateral cortex (treatment x sex; P < .05) was smaller in male calves from cows given 4 than in those from cows given 0 g of FGHD but was not affected in female calves. By 96 to 105 d after calving, a greater number of (P < .05) cows consuming 4 and 2 g of FGHD experienced luteal activity, and a greater (P < .10) number than of cows receiving 0 g of FGHD had conceived by 112 d after calving. In summary, pre- and postpartum consumption of FG may have impaired some aspects of calf skeletal development and vitamin metabolism, although long-term performance of cows and calves was not affected.

Acetates↗

PubMed1995

Influence of maternal and service-sire breed on serum progesterone and estrogen before calving and plasma 13,14-dihydro-15-keto-prostaglandin F2 alpha after calving.

Effects of breed of service sire and cow on birth weight and prepartum and postpartum endocrine function were studied in multiparous Brahman (n = 20) and Angus (n = 20) cows bred to Brahman or Angus bulls. Before calving, blood samples were collected on d 34 to 28, 27 to 21, 20 to 14, and 13 to 7, and after calving, samples were collected from d 0 to 7. Progesterone (P4), estrogen (E2), and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) were quantified with RIA. Calves born to Brahman were smaller (P < .05) than calves born to Angus cows. Prepartum concentrations of P4 were greater in Angus cows and decreased more rapidly near parturition than in Brahman cows (breed of dam x period; P < .03). Cows bearing bull calves had greater concentrations of P4 on d 20 to 14 before calving than cows bearing heifer calves (sex of calf x period; P < .04). Prepartum E2 was influenced (P < .05) by the breed of dam x breed of sire x period interaction. The ratio of P4:E2 tended to decrease more in Angus than in Brahman cows near parturition (breed of dam x period; P < .09). Postpartum PGFM tended to be influenced (P < .08) by breed of dam x breed of sire; from d 3 to 5, Brahman cows bred to Angus bulls tended (P < .08) to have greater PGFM than Brahman cows bred to Brahman bulls or than Angus cows bred to Brahman or Angus bulls.2+ f1p4

Animals↗

PubMed1995

Effect of ruminally undegradable protein from fish meal on growth and reproduction of peripuberal Brahman bulls.

Thirty-nine Brahman bulls (301.7 +/- 4.1 d; 202.7 +/- 4.7 kg) were allotted to one of two treatments and fed soybean meal (SBM)- or fish meal (FIS)-based supplements and hay to examine the effects of source of protein on growth and reproductive development. The fish meal supplement had 72% ruminally undegradable protein (RUP) and the soybean meal supplement had 47% RUP. Bulls assigned to the FIS treatment had higher (P < .01) total weight gain (81.2 +/- 1.4 vs 71.2 +/- 2.2 kg), higher (P < .01) ADG (.97 +/- .02 vs .85 +/- .03 kg), and better (P < .05) feed:gain ratio (7.6 +/- .1 vs 8.6 +/- .1 feed/BW gain for FIS vs SBM, respectively). Age at first motile spermatozoa was not affected (P > .05) by source of protein (429.9 +/- 9.6 vs 427.2 +/- 9.5 d, for bulls receiving FIS or SBM supplements, respectively). Likewise, age at puberty (473.3 +/- 21.7 d vs 465.9 +/- 12.9 d for bulls receiving FIS and SBM supplements, respectively) was similar for both treatment groups. There were no differences between treatments in scrotal circumference at those stages. At puberty semen quality was similar for bulls receiving FIS or SBM treatments, and no differences existed in LH and testosterone concentrations between treatments. We conclude that fish meal supplement increased growth but did not alter reproductive parameters in Brahman bulls.

Animal Feed↗

PubMed1995

Plasma cortisol and white blood cell responses in different breeds of bulls: a comparison of two methods of castration.

To determine plasma cortisol and white blood cell response to castration, Angus (n = 12, 21.4 mo of age), Hereford (n = 6, 21.2 mo of age), and Brahman (n = 24, 20.3 mo of age) bulls nearing maturity were either left intact as uncastrated controls (CON), surgically castrated (SUR) after lidocaine, or castrated by latex rubber banding (BAN). Before and through 35 d after castration (castration = d 0), animals were weighed and blood samples were collected for analysis of cortisol and total white blood cell (WBC) count at 2-, 3-, or 7-d intervals. There was a treatment x breed interaction for ADG from d 0 to 7 (P < .05). From d 0 to 14, 0 to 21, 0 to 28, and 0 to 35, ADG tended to be lower for SUR and BAN animals than for CON animals (castrated vs CON, P < or = .13). No significant differences in ADG were observed between SUR and BAN animals during these times. On d 0, from just before treatment to just after treatment, plasma cortisol concentration increased 3.2 ng/mL for SUR and .1 ng/mL for BAN (SEM = +/- .5 ng/mL; SUR vs BAN, P < .03). From d 0 pretreatment to d 2 after treatment, plasma cortisol concentration increased 1.5 ng/mL for castrated (SUR = 2.0 and BAN = 1.1 ng/mL) and decreased 1.6 ng/mL for CON (SEM = +/- .7 ng/mL; P < .04). Plasma cortisol concentration was negatively correlated (P < .001) with BW (r = -.17) and BW change (r = -.19).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Local↗

PubMed1995

Preweaning growth of Angus- (Bos taurus), Brahman- (Bos indicus), and Tuli- (Sanga) sired calves and reproductive performance of their Brahman dams.

Calves born to Angus (A), Brahman (B), or Tuli (T) bulls and B cows were evaluated to determine sire breed of calf effects on preweaning calf growth and reproductive performance of their dams. Records from 242 cow-calf pairs over 2 yr were used to assess birth weight, calf ADG, weaning weight, gestation length, and postpartum interval to estrus (PPI). The sire breed x sex of calf interaction was important (P < .05) for birth weight, weaning weight, and gestation length. Birth weights of BB males (32.8 +/- .8 kg) were significantly heavier than for AB and TB males (30.1 +/- .9 and 28.6 +/- .7 kg, respectively) and BB females (29.4 +/- .7 kg). As a main effect, sire breed of calf affected (P < .05) calf ADG, weaning weight, gestation length, and PPI. Calf ADG and weaning weights were greater for AB (.90 +/- .01 kg/d; 220.9 +/- 3.5 kg) than for TB (.81 +/- .01 kg/d; 200.4 +/- 3.0 kg) and BB calves (.78 +/- .01 kg/d; 198.8 +/- 3.5 kg). Gestation lengths differed (P < .01) among all calf genotypes (284, 288, and 294 +/- 1 d for AB, TB, and BB, respectively). Postpartum intervals were shorter (P < .05) for cows nursing BB calves (83 +/- 4 d) than for cows nursing AB (95 +/- 5 d) and TB calves (97 +/- 4 d). Tuli-sired F1 calves were inferior to Angus-sired F1 calves and similar to straightbred Brahman calves in preweaning growth. Crossbred calves had shorter gestations but longer postpartum intervals than purebred calves.

Aging↗

PubMed1994

Methods for pregnancy determination and the effects of body condition on pregnancy status in Rocky mountain elk (Cervus elephus nelsoni ).

The objective of this study was to determine the effectiveness of transrectal ultrasonography and serum progesterone (P(4)), estrone sulfate (E(1)S) and pregnancy-specific protein B (PSPB), without prior knowledge of reproductive status, in detecting pregnancy in elk cows. In addition, body weight and body condition score (BCS) were determined to assess whether body condition affects pregnancy status in elk cows. Twenty-five elk cows were sampled during the early rut (Period 1) and after the rut (Period 2), an interval of 120 d. Age, weight, BCS and blood samples, for P(4), E(1)S and PSPB determinations, were taken at Periods 1 and 2. Ultrasonography was performed at Period 2. The younger elk cows weighed less (P<0.05) than older cows. However, pregnancy status was not affected (P> 0.10) by age or weight of the cow. Elk cows that calved had higher (P<0.02) BCS at Periods 1 and 2 than cows that remained open. Serum P(4) and E(1)S were higher (P<0.0001) in pregnant cows at Period 2 than in open cows. Progesterone was 85.8% accurate in detecting pregnant versus open cows at Period 1, while E(1)S and PSPB were not effective. Elk cows at Period 1 were <20 d pregnant with the exception of 1 cow at 46 d. Ultrasonography was 92% accurate, P(4) was 95% accurate, and E(1)S and PSPB were both 100% accurate in determining pregnant versus open cows at Period 2. Pregnant cows at Period 2 were all > 100 d pregnant. Ultrasonography, serum E(1)S and PSPB all may provide a reliable means for pregnancy diagnosis in elk cows at > 100 d of gestation, while serum P(4) may be effective when multiple samples are compared during or after the rut, or when used in combination with the other diagnostic methods described. Further research is needed to determine the optimum time period after breeding in elk cows for accurate pregnancy detection through hormonal analysis.

Journal Article↗

PubMed1994

Serum luteinizing hormone, 13,14-dihydro-15-keto-prostaglandin F2alpha and cortisol profiles during postpartum anestrus in Brahman and Angus cows.

Pluriparous suckled Brahman and Angus cows were utilized to evaluate the effect of breed, day after calving and endogenous opioid peptides (EOP) on hormonal profiles during postpartum anestrus. On Days 17 and 34 after calving, blood samples with and without heparin were collected at 15- and 30-min intervals, respectively, for a 7-h period via jugular cannula. Two hours after the start of blood sampling, cows of each breed were administered either 1 mg/kg iv naloxone or saline. Three hours later, all animals received 10 ng/kg iv GnRH. On Day 34 after calving cows received 0.2 IU/kg iv ACTH. Mean LH, basal LH and area under the LH curve increased (P < 0.01) from Day 17 to Day 34 after calving. Height of LH pulses increased (P < 0.05) by Day 34 after calving. Brahman cows had higher (P < 0.05) mean LH, basal LH, LH pulse frequency and area under the LH curve than Angus cows. Naloxone increased postchallenge area under the LH curve in treated cows above that of control cows (P < 0.06). Naloxone also increased the postchallenge area under the LH curve above that of the prechallenge level (P < 0.01). No breed differences in the response to the naloxone challenge were observed. The LH response to naloxone challenge occurred earlier on Day 34 than on Day 17 after calving but the amount of LH released was similar between days. The GnRH-induced LH release was greater in Brahman than in Angus cows (P < 0.04). Mean cortisol concentrations and area under the cortisol curve decreased (P < 0.05) between Day 17 and Day 34 after calving. Mean cortisol concentrations and area under the cortisol curve were lower (P < 0.01) in Brahman than in Angus cows. Cortisol secretion after ACTH treatment was similar between Brahman and Angus cows. The cortisol response after ACTH challenge was positively correlated (r=0.68; P < 0.001) to the prechallenge area under the cortisol curve. Under optimal environmental conditions Brahman cows have a greater LH release and their anterior hypophysis is more sensitive to GnRH challenge than the Angus cows.

Journal Article↗

PubMed1994

Follicular dynamics, embryo production, and hormonal responses in Brahman heifers following sympathetic stimulation.

The purpose of this experiment was to characterize adrenal and ovarian responses to N-methyl-beta-phenethylamine (NMP) or ACTH. Thirty-three heifers with functional midcycle corpora lutea were placed on a 4-d superovulation regimen. They were injected twice daily with FSH-P and either saline (Control), ACTH (80 IU), or NMP (1 mg/kg BW). An initial blood collection preceded jugular delivery of saline, NMP, or ACTH, i.m. delivery of FSH and PGF2 alpha (d 3), and ultrasound (d 1 to 4). A second blood collection was made 6 min after treatment. Sampling continued daily until d 13. Embryos (age 6 to 7 d) were collected and evaluated. Concentrations of cortisol (posttreatment minus pretreatment) were greatest (P < .05) in NMP- and ACTH-treated heifers. Treatment did not affect mean numbers of small (< 4 mm), large (> 8 mm), or total follicles on d 2 to 4. Heifers receiving NMP had fewer medium follicles (4 to 8 mm) on d 2 and 3, and ACTH-treated heifers had fewer medium follicles on d 4 (P < .07). Mean estradiol concentrations on d 2 to 4 were unaffected by treatment (P > .32). Following PGF2 alpha, time to onset of standing estrus was less (P < .05) in Control than in ACTH- and NMP-treated heifers (41.4 vs 47.9 and 58.9 h, respectively). A greater frequency (P < .05) of reproductive anomalies (no estrus; no ovulation [i.e., progesterone < 1 ng/mL]; luteal failure [i.e., progesterone < 1 ng/mL but embryos recovered]) occurred in NMP (5/11) than in Control (0/10) or ACTH (2/10) heifers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1994

Growth and reproductive development in Brahman bulls fed diets containing gossypol.

To determine the effect of gossypol on growth and reproductive development, Brahman bulls (n = 30) were fed diets containing gossypol (6 or 60 mg.kg BW-1.d-1) or a diet free of gossypol from weaning through puberty. Diets contained cottonseed meal (CSM), whole cottonseed (WCS), or soybean meal (SBM) as the major sources of dietary CP. Diets were formulated to provide similar NEg for medium-framed bulls to gain .9 kg/d. Measurements of BW and scrotal circumference were obtained at 28-d intervals, and beginning at 10 mo of age electroejaculates were collected at 14-d intervals. By 196 d on feed, bulls fed WCS had gained less (P < .05) BW and tended (P < .10) to have lower gain/feed than bulls fed CSM. When spermatozoa were first detected in an ejaculate, bulls fed CSM tended (P < .10) to be younger than bulls fed WCS (357 vs 386 d; SBM = 380 d); bulls fed SBM were heavier (P < .05) than bulls fed gossypol (333 vs 310 kg), but they had similar scrotal circumferences. Bulls fed WCS reached puberty at an older (P < .05) age (613 d) than bulls fed CSM (528 d; SBM = 550 d) but had similar BW and scrotal circumferences. Electroejaculated semen quality and quantity did not differ (P > .10) between treatments at puberty. Seminiferous tubule diameters did not differ (P > .10) among treatments, but bulls fed diets that contained gossypol had larger (P < .01) lumenal diameters, smaller (P < .01) germinal epithelium thickness, and fewer (P < .01) germ cell layers than bulls fed SBM diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1994

Effects of phenolic monoamines on release of luteinizing hormone stimulated by gonadotropin-releasing hormone and on plasma adrenocorticotropic hormone, norepinephrine, and cortisol concentrations in wethers.

Eighteen Suffolk and Suffolk x Hampshire wethers (56.3 +/- 1.3 kg) were used to determine the effects of naturally occurring amines, N-methyl-beta-phenethylamine (NMP) and tyramine (T), on plasma cortisol, norepinephrine (NE), ACTH, and GnRH-stimulated LH concentrations. In each experiment, wethers were assigned randomly to treatments with six replicates/treatment. In Exp. 1, treatments consisted of saline, 2 mg of NMP/kg BW (NMP2), or 4 mg of NMP/kg BW (NMP4). In Exp. 2, treatments consisted of saline, 4 mg of NMP/kg BW (N), or 2 mg of NMP + 4 mg of T/kg BW (NT). All treatments were given via indwelling jugular catheters in single doses of 2 mL. In Exp. 1, no effects of time after treatment on response were detected. The NMP2 wethers had lower cortisol and LH peak amplitudes (PKAMP) than other wethers (P < .03 and .05, respectively). Time to peak (PKT) concentration of NE was significantly shorter in NMP4-treated wethers (P < .004). In Exp. 2, significant interactions between time and treatment were detected for cortisol, NE, and LH. Cortisol and NE concentrations were increased (P < .0001 and P < .03, respectively) in N- and NT-treated wethers compared with controls, whereas LH was reduced (P < .003). The N and NT treatments increased cortisol PKT, peak height (PKHT), and PKAMP above that of controls (P < .02, < .006, and < .02, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗

PubMed1994

Interactions between large and small bovine luteal cells in a sequential perifusion co-culture system.

The objectives of this experiment were to study large and small luteal cell interactions and examine the effect of arachidonic acid (AA) on progesterone production by separated bovine luteal cells. Corpora lutea collected from Holstein cows (n = 5) on d 12 of the estrous cycle were dispersed, and small (SLC) and large (LLC) luteal cells were separated by unit gravity sedimentation and flow cytometry. Cells were incubated at 37 degrees C in separate perifusion chambers with a modified Ham's F-12-HEPES medium and aerated with 95% O2:5% CO2. The flow rate of medium was 100 microL/min, and fractions were collected at 30-min intervals for 4 h. Luteal cells were arranged in tandem so that medium from the first cell type would pass through the chamber containing the second cell type. Luteal cells were arranged so that medium flowed from 1) SLC to SLC, 2) LLC to LLC, 3) SLC to LLC, 4) LLC to SLC, 5) SLC to LLC, 6) LLC to SLC; medium for arrangements 5 and 6 contained 10 microM AA. Cells in arrangements 5 and 6 were perifused for 30 min before AA was added. Progesterone was measured with an enzymeimmunoassay. The LLC to LLC arrangement had a greater (P < .05) average progesterone secretion rate than all other cell arrangements, and the SLC to SLC arrangement had the least progesterone secretion rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effects of postpartum nutrition and once-daily suckling on reproductive efficiency and preweaning calf performance in fall-calving Brahman (Bos indicus) cows.

Brahman cows were used to evaluate the effects of postpartum nutrition and suckling on reproductive and calf performance. Cows received high or low TDN and once-daily or unrestricted suckling. High TDN (H; 111% of NRC recommendation) cows received a 75% corn: 25% soybean meal diet. Low TDN (L; 93% of NRC recommendation) cows received no concentrates. Once-daily suckled (restricted, R) cows nursed calves for 30 min/d starting at d 21 after calving. In the unrestricted (U) suckling groups, calves had continuous access to cows. By 2 wk of suckling restriction, more (P < .01) R than U cows had progesterone concentrations of > or = .7 ng/mL (55 vs 0%) and more (P < .05) HR than LR cows had progesterone concentrations > or = .7 ng/mL (70 vs 40%). All groups had increases in progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha before estrus. The interval to first estrus was shorter (P < .01) for R than for U cows (42 vs 65 d). By d 42 postpartum, more (P < .01) R than U cows exhibited estrus (67 vs 0%), and more (P < .05) HR than LR cows exhibited estrus (89 vs 44%). Calving interval was shorter (P < .01) for R than for U cows (361 vs 395 d). Initial ADG were lower (P < .01) for R than for U calves (.02 vs .69 kg), but weaning weights were similar. Once-daily suckling permitted ovarian activity, hastened return to estrus, and reduced calving interval without reducing weaning weights. Increased postpartum energy intake enhanced the response to restricted suckling.

Anestrus↗

PubMed1993

Effect of dietary energy on growth and reproductive characteristics of Angus and Senepol bulls during summer in Florida.

Pubertal Angus bulls (n=10, 503 days of age and weighing 366 kg) and Senepol bulls (n=10, 457 days of age and weighing 381 kg) were stratified by age and weight into 2 dietary treatments formulated to provide equal amounts of crude protein and 75% (below) or 150% (above) of the maintenance requirements for metabolizable energy. Measurements to assess body growth and libido were collected at 28-day intervals for 112 days (June through September). Twice during each 28-day interval, the bulls were subjected to breeding soundness examinations. At the end of the experiment, gonadotropin releasing hormone (GnRH) - induced secretion of luteinizing hormone (LH) and testosterone (T) in the serum were determined. At the end of the experiment, bulls fed the above maintenance diet (P<0.0001) were 91 kg heavier, had 1.7 mm more backfat thickness and 12.6 cm(2) larger ribeye area than bulls on a below maintenance diet. Diet affected (P<0.003) the average daily change in scrotal circumference, but not the libido score (P>0.1) or semen quality. In general, Angus bulls had superior initial semen quality (P<0.06); however, during summer, semen quality tended to decrease in Angus but not in Senepol bulls. The final rectal temperature was 0.5 degrees C lower (P<0.003) in Senepol than in Angus bulls. Basal T concentrations and area under the GnRH-induced T curve were greater (P<0.07) for bulls fed the above rather than the below maintenance diet. Angus bulls had a higher (P<0.03) maximal LH response to GnRH and larger area under the GnRH-induced LH curve than Senepol bulls.

Journal Article↗

PubMed1992

Concentrations of 13, 14-dihydro-15-keto-prostaglandin F(2)alpha, estradiol-17beta and progesterone during the peripubertal period in heifers.

Twenty prepubertal Holstein heifers were utilized to assess plasma 13, 14-dihydro-15-keto-prostaglandin F(2)alpha (PGFM), serum progesterone (P(4)) and estradiol-17beta (E(2)) concentrations as well as the E(2):P(4) ratio during the onset of puberty in cattle. All animals were maintained as a group along with a sterile marker bull to assist in the detection of estrus. Upon detection of the first estrus (Day=O), daily blood samples were collected from a jugular vein until the heifers had completed 3 estrous cycles. The average body weight and age at first estrus were 247.6+/-4.8 kg and 304.0+/-7.5 days, respectively. Frequency of abnormal length estrous cycles was greater (P<0.02) during the first (40%) and second (35%) cycles than during the third estrous cycle (0%). All heifers had normal cycle lengths (18 to 24 days) by the third estrous cycle. Serum P(4) was greater during the third cycle (P<0.05) from Day 10 to Day 4 before the next estrus compared with the same period of the first estrous cycle. Serum E(2) did not peak until the day of estrus in the first cycle, whereas E(2) reached a maximal level 2 days before estrus in the third estrous cycle. Serum E(2) was higher (P<0.0001) 2 days before estrus in the third cycle than in the first estrous cycle. Plasma PGFM reached maximum concentrations 3 days before estrus in the third cycle compared with 1 day before estrus at the end of first estrous cycle. As estrus approached during the third cycle, PGFM rose 1 day before E(2) rose and P(4) declined, while the rise in PGFM and E(2) occurred simultaneously, with P(4) declining at the end of the first estrous cycle. During diestrus, the E(2):P(4) ratio was lower (P<0.07) in the third cycle than in the first, but it was higher (P<0.04) at estrus and 1 day before in the third estrous cycle. These data reveal a high incidence of abnormal length estrous cycles during the first two estrous cycles of the peripubertal period, and demonstrate anomalies in uterine and ovarian endocrine activity during the peripubertal period in cattle.

Journal Article↗

PubMed1992

Cortisol and prolactin concentrations during three different seasons in relocated Brahman and Hereford bulls.

The objective of this study was to evaluate seasonal changes of cortisol and prolactin (PRL) concentrations in Brahman and Hereford bulls moved to locations that differ in geographical and environmental conditions. Postpubertal Hereford bulls from Montana (n = 15) and Nebraska (n = 15) and Brahman bulls from Texas (n = 18) were located in or relocated to Montana, Nebraska or Texas so that each location had 5 Montana Herefords, 5 Nebraska Herefords and 6 Texas Brahman bulls. Blood samples were collected at 20-minute intervals for 8 hours in November (Fall 1), April (Spring) and November (Fall 2) of the next year. These dates corresponded to 6, 12 and 18 months, respectively, after relocation in May of the first year. Cortisol concentrations were higher (P<0.05) in Fall 1 than in Fall 2 and were higher (P<0.05) for bulls in Montana than for bulls in Texas. The decrease in cortisol concentrations from Fall 1 to Fall 2 was negatively related (P<0.05) to age and weight. There was a three-way interaction (P<0.05) of breed-type origin, location and season for PRL concentrations. Seasonal patterns of PRL concentrations differed between relocated Texas Brahman and Hereford bulls, and patterns for relocated bulls differed from those of the nonrelocated bulls. Seasonal patterns of PRL were influenced to a greater extent by relocation in Texas Brahman bulls than in Hereford bulls.

Journal Article↗

PubMed1992

Effects of exogenous glucose or colostrum on body temperature, plasma glucose, and serum insulin in cold-stressed, newborn Brahman calves.

The effects of ambient temperature and source of exogenous energy (glucose or colostrum) on the ability of newborn Brahman calves to maintain rectal temperature (RT) were determined. All calves were removed from dams within 30 min of birth, before suckling. Calves were catheterized and placed in either a warm (25 degrees C) or cold (5 degrees C) environment for 150 min and given either colostrum or glucose. This resulted in four groups (warm colostrum, n = 7; cold colostrum, n = 7; warm glucose, n = 6; cold glucose, n = 6). Blood samples and RT were obtained at 15-min intervals during warm or cold through 150 min, when calves were removed from cold, and at 180, 240, and 300 min. After 60 min, each calf was given either 1 L of colostrum (38 degrees C) from its dam or glucose (38 degrees C) infusion of 750 mg/kg BW. Plasma glucose concentrations were determined by enzymatic techniques and serum insulin concentrations by RIA. Calves exposed to cold or warm air temperatures had similar declines in rectal temperature from 0 to 60 min. Colostrum-fed, cold calves had a greater (P less than .07) decrease in RT than did colostrum-fed, warm calves from 75 through 150 min; glucose-infused warm and cold calves had intermediate decreases in RT. Plasma glucose increased (P less than .0001) in glucose-infused compared with colostrum-fed calves at 75 min, but glucose-infused calves had lower (P less than .02) glucose levels from 180 to 300 min. Higher (P less than .05) glucose concentrations

Animals↗

PubMed1992

Behavioral and physiological effects of freeze or hot-iron branding on crossbred cattle.

Twenty-seven crossbred calves (1/2 Simmental, 1/4 Hereford, 1/4 Brahman) averaging 257 +/- 11 d of age were either hot-iron-branded (H), freeze-branded (F), or sham-branded (S). Calves were blocked for temperament, weight, and sex and were randomly assigned to day and order in which treatments were applied. To reduce stress from handling at treatment time, each calf was herded through the squeeze chute daily for 5 d before the experiment. Jugular cannulas were inserted in each calf 1 d before application of treatment. Blood samples and heart rate measures were obtained at -5, -3, 0, .5, 1, 3, 5, 10, 15, and 20 min after application of the treatments. Mean concentrations of plasma epinephrine (EPI) were higher for H calves at time .5 min than for either S or F calves (P = .10). To account for individual differences, prebranding heart rates and hormone concentrations were subtracted from subsequent samples and were also used to calculate a proportion for each subsequent sample. Analyses of subtracted values found that EPI concentrations were greater for H calves than for either S or F calves (P = .007) at .5 min postbranding. No other differences were found for the subtracted analyses. Analyses of proportion data also revealed that H calves had greater EPI than did either S or F calves (P = .027) at .5 min postbranding. Only three animals vocalized during branding, one H calf and two F calves. Despite the 5-d acclimation period, handling and restraint elevated plasma cortisol concentrations and heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Identification Systems↗

PubMed1992

In vitro metabolism of glucose by bovine reproductive tissues obtained during the estrous cycle and after calving.

Two experiments were conducted to determine the effect of physiological state (stage of the estrous cycle or time after calving) on the in vitro metabolism of glucose by reproductive tissues. In Exp. 1, the corpus luteum and ipsilateral uterine horn were collected at surgery from 15 cows at early (d 6 to 7), middle (d 10 to 13), or late (d 17 to 19) stages of the estrous cycle. Luteal or endometrial tissues (45 mg) were incubated (4 h, 37 degrees C) in metabolic flasks containing Nutrient Mixture F-10 (3 mL), increasing concentrations of glucose (1, 2, 5, 10, or 15 mM), and 1 microCi of [U-14C]glucose. Luteal tissue collected at the middle stage of the estrous cycle had greater (P less than .04) rates of glucose uptake (17.8 vs 12.1 ng/mg of wet tissue per min) and oxidation (138.6 vs 67.7 pg/mg of wet tissue per min) and a lower (P less than .02) rate of metabolism of glucose to lactate (10.5 vs 13.3 ng/mg of wet tissue per min) than tissue collected at the late stage. Compared to tissue collected at early and late stages, endometrial tissue collected at the middle stage of the estrous cycle had a similar (P greater than .5) rate of glucose uptake (29.6 vs 27.8 and 26.1 ng/mg of wet tissue per min), a lower (P less than .02) rate of metabolism of glucose to lactate (13.8 vs 16.6 and 16.4 ng/mg of wet tissue per min), and a greater (P less than .1) rate of oxidation of glucose (84.1 vs 65.8 and 72.3 pg/mg of wet tissue per min). In Exp. 2, the previously gravid uterine horn was collected at surgery on d 20 (n = 8) or 30 (n = 7) after calving, or the uterine horn ipsilateral to the preovulatory follicle was collected at first observed estrus after calving (n = 8). Uterine tissue obtained at first estrus after calving had a greater (P less than .003) rate of glucose uptake and oxidation (88.8 vs 77.3 and 75.5 pg/mg of tissue per min) than d-20 or d-30 endometrium.(ABSTRACT TRUNCATED AT 250 WORDS)

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