The influence of zeranol implantation on growth and reproduction of beef heifers

1991 ◽  
Vol 71 (4) ◽  
pp. 1249-1252 ◽  
Author(s):  
R. N. Kirkwood ◽  
R. D. H. Cohen ◽  
B. D. King ◽  
P. A. Thacker
Keyword(s):  
Key Words ◽  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Growth Enhancement ◽  
Beef Heifers ◽  
Pelvic Area ◽  
Effect Of Treatment ◽  
Growth And Reproduction

Crossbred beef heifers received a 36-mg implant of zeranol at 60 d of age (R1; n = 35) or at both 60 and 197 d (weaning; R2; n = 32) or received no implants (C; n = 35). R2 heifers were heavier and had greater pelvic areas (P < 0.05 for both) at breeding compared with controls. There was no effect of treatment on the calving rates (78.1 vs. 80.0 vs. 74.3%) or on mean pelvic area at the time of calving (261.1 vs. 260.4 vs. 257.6 cm2) for R2, R1 and C heifers, respectively. We conclude that zeranol can be successfully used for growth enhancement from 60 d of age without detriment to subsequent reproductive performance. Key words: Zeranol, heifers, pregnancy rate, pelvic area

scholarly journals EFFECT OF REPEATED IMPLANTATION WITH ZERANOL FROM BIRTH OR WEANING ON GROWTH AND REPRODUCTION IN BEEF HEIFERS

1987 ◽  
Vol 67 (1) ◽  
pp. 37-42 ◽  
Author(s):  
R. D. H. COHEN ◽  
H. H. NICHOLSON ◽  
E. D. JANZEN
Keyword(s):  
Key Words ◽  
Pregnancy Rate ◽  
Skeletal Development ◽  
Carcass Characteristics ◽  
Reproductive Rate ◽  
Beef Heifers ◽  
Pelvic Area ◽  
Group B ◽  
Natural Service ◽  
Growth And Reproduction

Liveweight, pregnancy rate, skeletal development and carcass characteristics were measured on 52 crossbred beef heifers implanted with zeranol at birth then at 110, 204 and 314 d of age (B); at weaning (204 d of age) and at 314 d of age (W); or not implanted (C). At 14 mo of age, the heifers were bred for 6 wk in corrals by natural service. Six weeks later they were slaughtered and their reproductive tracts collected. Height at the withers and pelvic area were measured before slaughter. Mean weaning weights ± SD, corrected to 200 d and for age of dam, were 249 ± 20 kg for group B and 226 ± 22 kg for groups W and C (P < 0.001). At breeding, the heifers weighed 434 ± 24, 416 ± 29 and 392 ± 31 kg for groups B, W and C, respectively (P < 0.001). At slaughter, their liveweights were 531 ± 26, 508 ± 32 and 483 ± 36 kg, respectively (P < 0.001) and carcass weights were 304 ± 17, 286 ± 21 and 270 ± 20 kg, respectively (P < 0.001). Rib eye area was 84.3 ± 8.47, 76.5 ± 8.89 and 72 ± 7.81 cm2, respectively (P < 0.001) but there were no significant differences between groups for cutability (58.2 ± 1.85%), average fat cover (9.4 ± 0.84 mm) or grade (90.3% ± A1/A2 and 9.7% A3/A4). Height at the withers did not differ between groups (46.7 ± 1.61 cm) but zeranol increased pelvic area (186.4 ± 19.54, 178.6 ± 21.84 and 165.3 ± 21.14 cm2 zeranol for groups B, W and C, respectively; (P < 0.05). Pregnancy rate was significantly reduced (P < 0.05) in group B (42.9%) compared with groups W and C (84.2 and 77.8%, respectively). However, examination of the reproductive tracts indicated that only one nonpregnant heifer in each of groups B and C was not cycling and no other abnormalities were found. It was concluded that zeranol will increase live and carcass weights, rib eye area and pelvic area of heifers but that four implants given at birth and at approximately 100-d intervals to 314 d of age will reduce reproductive rate in comparison to heifers implanted twice postweaning or not implanted. Key words: Zeranol, heifer, growth, reproduction, pelvimetry, carcass

The influence of purified porcine relaxin on the reproductive performance of sows following artificial insemination with fresh or frozen semen

1991 ◽  
Vol 71 (1) ◽  
pp. 237-239 ◽  
Author(s):  
P. A. Thacker ◽  
A. D. Gooneratne ◽  
R. N. Kirkwood
Keyword(s):  
Key Words ◽  
Pregnancy Rate ◽  
Litter Size ◽  
Reproductive Performance ◽  
Artificial Insemination ◽  
Pregnancy Rates ◽  
Frozen Semen

Pregnancy rates and litter sizes following insemination of sows with fresh-extended and frozen-thawed semen averaged 71 vs. 53% and 10.6 vs. 4.4, respectively, and was not affected by the addition of 12.5 μg relaxin to semen. These results indicate no relaxin mediated effect on either pregnancy rate or litter size when sows are artificially inseminated with relaxin-supplemented semen. Key words: Artificial insemination, relaxin, sows

Effect of treatment with ivermectin on reproductive performance of yearling beef heifers

1995 ◽  
Vol 44 (2) ◽  
pp. 189-197 ◽  
Author(s):  
R.L. Larson ◽  
L.R. Corah ◽  
M.F. Spire ◽  
R.C. Cochran
Keyword(s):  
Reproductive Performance ◽  
Beef Heifers ◽  
Effect Of Treatment

scholarly journals Maternal factors and the prediction of dystocia in beef heifers

1993 ◽  
Vol 73 (2) ◽  
pp. 431-435 ◽  
Author(s):  
B. D. King ◽  
R. D. H. Cohen ◽  
S. McCormac ◽  
C. L. Guenther
Keyword(s):  
Birth Weight ◽  
Discriminant Analysis ◽  
Key Words ◽  
Caesarian Section ◽  
Stepwise Discriminant Analysis ◽  
Gestation Length ◽  
Maternal Factors ◽  
Beef Heifers ◽  
Factors Associated ◽  
Pelvic Area

Stepwise discriminant analysis was used to determine maternal factors associated with dystocia in 564 2-yr-old heifers bred to bulls with below breed average birth weights. Calf birth weight (n = 556) was consistently the most significant (P < 0.001) factor correlated (R2 = 0.31) with dystocia. Other significant (P < 0.001) factors were weight at breeding (n = 376) and calving (n = 559; R2 = 0.11 for both traits). Other factors considered were age at breeding (n = 446), pelvic area at breeding (n = 112) and pregnancy evaluation (n = 297), heifer birth weight (n = 564), gestation length (n = 467) and age at calving (n = 559) but none were significant (P > 0.05). Heifers requiring caesarian section were heaviest (P < 0.05) at breeding and their calves were heaviest (P < 0.05) at birth. Unassisted heifers were heavier at calving (P < 0.05) than assisted heifers. It was concluded that none of the factors examined in this study was a reliable predictor of dystocia in beef heifers but that heifers should be bred at 75–80% of their expected calving weight to reduce the risk of dystocia. Key words: Dystocia, heifer, discriminant analysis

The effect of zeranol implants on growth and pregnancy loss in beef heifers

1994 ◽  
Vol 74 (1) ◽  
pp. 73-76 ◽  
Author(s):  
B. D. King ◽  
R. N. Kirkwood ◽  
C. L. Guenther ◽  
R. D. H. Cohen ◽  
G. A. Bo ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Reproductive Performance ◽  
Pregnancy Loss ◽  
Average Daily Gain ◽  
Fetal Loss ◽  
Live Weight ◽  
Fetal Mortality ◽  
Beef Heifers ◽  
Calf Survival ◽  
Daily Gain

Live weight, average daily gain (ADG) and reproductive performance were compared between heifers implanted with zeranol at birth, 100 and 200 d of age (n = 54) and those not implanted (n = 50). Zeranol implantation resulted in increased (P < 0.05) ADG from birth to weaning, weaning weight, ADG from weaning to breeding, breeding weight and calving weight but did not affect (P > 0.05) calf birth weights, incidence of dystocia, calf survival or gestation lengths. Zeranol implants did not affect (P > 0.05) the incidence or magnitude of the pre-ovulatory LH surge or the number of heifers that ovulated between 48 and 168 h after cloprostenol injection. Pregnancy rate 42 d after bull entry did not differ between the two groups (P > 0.10), tended toward a difference at 72 d (P < 0.10), and was different at 133 d (P < 0.05), with implanted heifers having a lower pregnancy rate than non-implanted heifers. Between day 72 and day 133 after bull entry there was a 10% embryonic or fetal mortality rate in zeranol-implanted heifers, which differed from the 0% loss in non-implanted heifers (P < 0.05). We conclude that serial implants of zeranol from birth reduced the pregnancy rate in heifers and that this effect was due to early fetal loss. Key words: Zeranol, embryonic/fetal mortality, bovine, pregnancy rate, ultrasonography

The effects of catch-up (compensatory) growth on reproductive performance of beef heifers

1996 ◽  
Vol 76 (4) ◽  
pp. 523-529 ◽  
Author(s):  
Dinah Boadi ◽  
M. A. Price
Keyword(s):  
Key Words ◽  
Reproductive Performance ◽  
Compensatory Growth ◽  
Reproductive Efficiency ◽  
Feed Restriction ◽  
Early Weaning ◽  
Beef Heifers ◽  
Catch Up ◽  
Calving Performance

Fifty-four heifer calves were allocated to five feeding/weaning treatments at birth in April/May 1990: 1) VEW (n = 11) dams feed-restricted for 3 mo before and 2 mo after calving; calves weaned in June onto gram-supplemented pasture and then into a drylot in October; 2) EW1 (n = 10) dams not restricted; calves weaned in August (unsupplemented pasture) into drylot in October; 3) EW2 (n = 10) dams not feed-restricted; calves weaned directly into drylot in August; 4) LW1 (n = 12) dams feed restricted for 3 mo before, but not after calving; calves weaned directly into drylot in October, 5) LW2 (n = 11): dams not restricted; calves weaned directly into drylot in October. The very early (VEW) and early (EW1, EW2) weaned heifers grew significantly slower than the later-weaned ones (LW1, LW2) from birth to September, and were still significantly lighter at 12–13 mo of age (May 1991). Recovery of liveweight-for-age was achieved by EW2 heifers by 18 mo and VEW and EW1 by about 23 mo of age. Early weaning treatments delayed age but not weight at first estrus (P < 0.05) yet the number of heifers conceiving and calving, and all associated reproductive data, including rebreeding success were unaffected by treatment (P > 0.05). Despite a delay in first estrus, reproductive efficiency and calving performance were not impaired by early feed restriction in heifers conceiving at 15 mo of age. Key words: Beef heifers, feed restriction, fertility, reproduction, catch-up growth

Effects of a growth implant and age of dam on growth and fertility in heifer calves

1994 ◽  
Vol 74 (2) ◽  
pp. 203-208 ◽  
Author(s):  
L. M. Rutter ◽  
P. A. Day
Keyword(s):  
Treatment Group ◽  
Pregnancy Rate ◽  
Field Trial ◽  
Average Daily Gain ◽  
Beef Heifers ◽  
Pelvic Area ◽  
Calving Season ◽  
Growth Implant ◽  
Calving Difficulty ◽  
Daily Gain

A field trial was conducted to determine the effects of a growth implant on growth, pregnancy rate, calving difficulty and calf weaning weight in replacement beef heifers. Heifers were assigned equally to either a control (n = 43; no implant), Ralgro (n = 43) or Synovex-C (n = 42) treatment group based on age of dam and age and weight at the start of the trial (implantation at 45–90 d of age). Neither Ralgro nor Synovex-C enhanced heifer weight or average daily gain (ADG) from the start of the trial to weaning (approximately 7 mo of age), breeding, or pregnancy determination. At breeding, Synovex-C implanted heifers had greater pelvic area than controls while Ralgro implanted heifers were intermediate (control = 149.7, Ralgro = 154.7 and Synovex-C = 157.4 pooled SE of 2.2 cm2; P = 0.05). Pelvic dimensions were similar among treatments at pregnancy determination and there were no treatment effects on calving difficulty. Age of dam affected heifer weight (P = 0.0005) and ADG (P = 0.001) to weaning, with heifers from mature cows weighing more at weaning and having a higher ADG from the start of the study to weaning than heifers from either first- or second-calf cows. Post-weaning performance of heifers from first-calf cows was similar to heifers from mature cows while heifers from second-calf cows were lighter at breeding (P = 0.04) and had a lower ADG from weaning to breeding (P = 0.04). Age of dam did not influence pregnancy rate (P = 0.10), but more heifers from second-calf cows calved late in the calving season (≥ 64 d) compared with heifers from either first-calf or mature cows (P = 0.04). It appears from this field trial that use of a growth implant between 45 and 90 d of age neither enhanced growth nor impaired fertility in beef heifers bred as yearlings. It also appears that second-calf 3-yr-olds may need to be managed separately from the mature cow herd in order to optimize replacement heifer development. Key words: Bovine, replacement heifers, growth implant, age of dam, weight, pregnancy rate

scholarly journals Developmental and reproductive characteristics of beef heifers classified by number of estrous cycles experienced by start of first breeding

2018 ◽  
Vol 3 (1) ◽  
pp. 541-548 ◽  
Author(s):  
Andrew J Roberts ◽  
Jaclyn N Ketchum ◽  
Richard N Funston
Keyword(s):  
Pregnancy Rate ◽  
Estrous Cycle ◽  
Reproductive Performance ◽  
Beef Heifers ◽  
Estrous Cycles ◽  
Physical Maturation ◽  
Fat Thickness ◽  
Ad Libitum ◽  
Number Of Cycles ◽  
Cycle Group

Abstract A retrospective analysis was conducted to evaluate the effect of number of estrous cycles exhibited before breeding on growth and reproductive performance of replacement beef heifers fed ad-libitum or restricted by 20% less than ad-libitum during postweaning development over a 9-yr period. Progesterone concentration in blood samples collected at 9- to 11-d intervals were used to assign heifers into groups by number of estrous cycles exhibited before the start of breeding: 0 (nonpubertal; n = 395), 1 (n = 205), 2 (n = 211), 3 (n = 116), or &gt;3 (n = 249). Heifers (P &lt; 0.01) in the 0 cycle group were born 6 d later than the 1, 2, or 3 cycle groups, which were born 4 d later (P &lt; 0.01) than the &gt;3 cycle group. Weight of heifers at birth decreased (P &lt; 0.05) as the number of cycles increased. Weaning weight and ultrasound measures of loin area and fat thickness over the loin at 1 yr age increased as the number of cycles increased (P &lt; 0.01). Postwean weight gain, hip height at 1 yr age, and weights from the start of breeding through precalving increased with cycle numbers in a quadratic fashion (P &lt; 0.02) and were greater (P &lt; 0.05) in ad-libitum than restricted-fed heifers. Pregnancy rate in the 0 cycle group was lower (84%; P &lt; 0.05) than the 1 (90%) or &gt;3 (94%) estrous cycles groups and tended to differ (P &lt; 0.1) from the 2 (88%) and 3 (89%) estrous cycle groups. Interval from the start of breeding to calving was 3 to 5 d longer (P &lt; 0.05) for the 0 cycle group (300 ± 1 d) than other groups. Proportion of heifers calving in the first 21 d was less (P &lt; 0.05) in the 0 or 1 cycle groups than other groups. Pregnancy rates of 2-yr-old cows (n = 898) were lowest (P &lt; 0.05) for the 0 (73%) and 2 (79%) estrous cycle groups than the 1 (85%), 3 (90%), or &gt;3 (92%) estrous cycle groups. Restricted level of feeding during postweaning development resulted in greater (P &lt; 0.05) proportion of heifers in 0 cycle group and lower (P &lt; 0.05) proportion in &gt;3 cycle group, but reproductive performance was not influenced (P &gt; 0.1) by level of feeding or interaction of feeding and estrous cycle grouping. In summary, date of birth and rate of physical maturation (weight, height, and fat deposition) were associated with timing of puberty. Pregnancy rate was greater in heifers that exhibited estrus before the start of breeding, but did not improve from having more than one estrous cycle. Proportion conceiving early was greater for heifers having two or more cycles before breeding.

EFFECTS OF EXPOSURE TO BULLS AND BODY WEIGHT ON REPRODUCTIVE PERFORMANCE IN BEEF HEIFERS

1985 ◽  
Vol 65 (1) ◽  
pp. 31-36 ◽  
Author(s):  
M. MAKARECHIAN ◽  
A. FARID ◽  
R. T. BERG
Keyword(s):  
Body Weight ◽  
Pregnancy Rate ◽  
Breeding Season ◽  
Reproductive Performance ◽  
Control Group ◽  
Group Effect ◽  
Beef Heifers ◽  
Heavy Body ◽  
Breed Group ◽  
Calving Season

Calving records of 174 2-yr-old heifers from four breed groups; Hereford (HE), Beef Synthetic (SY), Dairy Synthetic (SD) and Crossbred Hereford (HX) were used in this study. Half of the heifers were exposed to three epididymectomized bulls for 6 wk before the start of the breeding season. While exposure to bulls had little influence (P = 0.51) on pregnancy rate, it advanced the calving date by 5.5 days compared with the control group (P < 0.05). Calving season in the exposed heifers was 2 wk shorter than that in the control group. Effect of heifer body weight at the start of breeding season on pregnancy rate differed (P < 0.05) among the four breed groups. Low body weight at mating was associated with lowered fertility in SY, SD and HE while very heavy body weight resulted in lowered fertility in SY and SD breed groups. Increase in body weight advanced calving date in the HX breed group only. Key words: Beef cattle, heifer reproduction, bull exposure, body weight

Repeatability estimates of pelvic diameters measured by Rice pelvimeter in beef heifers

1993 ◽  
Vol 73 (4) ◽  
pp. 977-980
Author(s):  
U. Paputungan ◽  
M. Makarechian ◽  
M. F. Liu
Keyword(s):  
Key Words ◽  
Intraclass Correlation ◽  
Correlation Method ◽  
Reliable Estimate ◽  
Residual Variance ◽  
Beef Heifers ◽  
Single Measurement ◽  
Pelvic Area ◽  
Beef Heifer

Vertical (VP) and horizontal (HP) pelvic diameters were measured with Rice pelvimeter four times in a 3-wk period by the same operator in 143 bred beef heifers (18 ± 0.5 mo old). Pelvic area (PA) was estimated by VP × HP. Pelvic diameters of 30 open beef heifers (19 ± 0.3 mo old) were also measured by two experienced and two inexperienced operators. Repeatability of pelvic measurements was estimated by the intraclass correlation method. The estimates of repeatability of pelvic measurements were relatively moderate (0.53 ± 0.04, 0.46 ± 0.04 and 0.55 ± 0.04 for VP, HP and PA, respectively), indicating that a single measurement may not provide a reliable estimate of pelvic diameter. Between-operator variance was much smaller than the residual variance for each measurement (0.02 vs. 0.39 for VP, 0.06 vs. 0.36 for HP and 38.15 vs. 276.18 for PA). Key words: Beef heifer, pelvic diameters, repeatability

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