Norgestomet implants prevent pregnancy in beef heifers on pasture

T. W. Geary, J. J. Reeves, David W Schafer, R. R. Evans, R. D. Randel, L. M. Rutter, R. G. Sasser, R. Guardia, B. Alexander, D. Holcombe, D. R. Hanks, Dan B Faulkner

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The efficacy of erodible norgestomet implants for preventing pregnancy in postpubertal heifers was evaluated in two experiments at five locations each. Heifers (n = 896) within each study location were stratified by weight and allotted randomly to receive an ear implant containing either 0, 24, 36, or 48 mg of norgestomet (d 0). Heifers were exposed to fertile bulls immediately after implantation for 75 d (d 0 to 74) in Exp. 1 (n = 476) or for 80 d (d 75 to 154) in Exp. 2 (n = 420). Weights were recorded on d O and 74 (Exp. 1 and 2) and d 154 (Exp. 2). Each heifer was palpated rectally for pregnancy at the end of each experiment. Pregnancy rates were higher (P < .01) for control heifers (0 mg implant) than for heifers that received 24, 36, or 48 mg of norgestomet. In Exp. 1, pregnancy rates were 96, 29, 6, and 4% for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. In Exp. 2, pregnancy rates were 85, 36, 19, and 9% for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. Estrous activity during the first 3 wk of bull exposure was reduced (P < .05) among heifers that received norgestomet implants compared to control heifers but was not completely abolished at any dosage in Exp. 1. During the first 75 d of Exp. 1 and 2, heifers treated with 36 or 48 mg norgestomet implants gained weight faster (P < .05) than control heifers. Combined across both experiments, ADG during the first 74 d were .53, .56, .59, and .60 kg/d for heifers treated with 0, 24, 36, and 48 mg implants of norgestomet, respectively. These data indicate that norgestomet implants increased rate of weight gain, reduced estrous activity, and reduced the occurrence of pregnancy in heifers on pasture.

Original languageEnglish (US)
Pages (from-to)3089-3093
Number of pages5
JournalJournal of Animal Science
Volume75
Issue number12
StatePublished - Dec 1997
Externally publishedYes

Fingerprint

norgestomet
beef cattle
heifers
pastures
pregnancy
Pregnancy
Pregnancy Rate
Weights and Measures
pregnancy rate
bulls
Weight Gain
Ear

Keywords

  • Beef Cattle
  • Females
  • Fertility
  • Heifers
  • Pastures
  • Progestogens

ASJC Scopus subject areas

  • Animal Science and Zoology

Cite this

Geary, T. W., Reeves, J. J., Schafer, D. W., Evans, R. R., Randel, R. D., Rutter, L. M., ... Faulkner, D. B. (1997). Norgestomet implants prevent pregnancy in beef heifers on pasture. Journal of Animal Science, 75(12), 3089-3093.

Norgestomet implants prevent pregnancy in beef heifers on pasture. / Geary, T. W.; Reeves, J. J.; Schafer, David W; Evans, R. R.; Randel, R. D.; Rutter, L. M.; Sasser, R. G.; Guardia, R.; Alexander, B.; Holcombe, D.; Hanks, D. R.; Faulkner, Dan B.

In: Journal of Animal Science, Vol. 75, No. 12, 12.1997, p. 3089-3093.

Research output: Contribution to journalArticle

Geary, TW, Reeves, JJ, Schafer, DW, Evans, RR, Randel, RD, Rutter, LM, Sasser, RG, Guardia, R, Alexander, B, Holcombe, D, Hanks, DR & Faulkner, DB 1997, 'Norgestomet implants prevent pregnancy in beef heifers on pasture', Journal of Animal Science, vol. 75, no. 12, pp. 3089-3093.
Geary TW, Reeves JJ, Schafer DW, Evans RR, Randel RD, Rutter LM et al. Norgestomet implants prevent pregnancy in beef heifers on pasture. Journal of Animal Science. 1997 Dec;75(12):3089-3093.
Geary, T. W. ; Reeves, J. J. ; Schafer, David W ; Evans, R. R. ; Randel, R. D. ; Rutter, L. M. ; Sasser, R. G. ; Guardia, R. ; Alexander, B. ; Holcombe, D. ; Hanks, D. R. ; Faulkner, Dan B. / Norgestomet implants prevent pregnancy in beef heifers on pasture. In: Journal of Animal Science. 1997 ; Vol. 75, No. 12. pp. 3089-3093.
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abstract = "The efficacy of erodible norgestomet implants for preventing pregnancy in postpubertal heifers was evaluated in two experiments at five locations each. Heifers (n = 896) within each study location were stratified by weight and allotted randomly to receive an ear implant containing either 0, 24, 36, or 48 mg of norgestomet (d 0). Heifers were exposed to fertile bulls immediately after implantation for 75 d (d 0 to 74) in Exp. 1 (n = 476) or for 80 d (d 75 to 154) in Exp. 2 (n = 420). Weights were recorded on d O and 74 (Exp. 1 and 2) and d 154 (Exp. 2). Each heifer was palpated rectally for pregnancy at the end of each experiment. Pregnancy rates were higher (P < .01) for control heifers (0 mg implant) than for heifers that received 24, 36, or 48 mg of norgestomet. In Exp. 1, pregnancy rates were 96, 29, 6, and 4{\%} for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. In Exp. 2, pregnancy rates were 85, 36, 19, and 9{\%} for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. Estrous activity during the first 3 wk of bull exposure was reduced (P < .05) among heifers that received norgestomet implants compared to control heifers but was not completely abolished at any dosage in Exp. 1. During the first 75 d of Exp. 1 and 2, heifers treated with 36 or 48 mg norgestomet implants gained weight faster (P < .05) than control heifers. Combined across both experiments, ADG during the first 74 d were .53, .56, .59, and .60 kg/d for heifers treated with 0, 24, 36, and 48 mg implants of norgestomet, respectively. These data indicate that norgestomet implants increased rate of weight gain, reduced estrous activity, and reduced the occurrence of pregnancy in heifers on pasture.",
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AU - Randel, R. D.

AU - Rutter, L. M.

AU - Sasser, R. G.

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N2 - The efficacy of erodible norgestomet implants for preventing pregnancy in postpubertal heifers was evaluated in two experiments at five locations each. Heifers (n = 896) within each study location were stratified by weight and allotted randomly to receive an ear implant containing either 0, 24, 36, or 48 mg of norgestomet (d 0). Heifers were exposed to fertile bulls immediately after implantation for 75 d (d 0 to 74) in Exp. 1 (n = 476) or for 80 d (d 75 to 154) in Exp. 2 (n = 420). Weights were recorded on d O and 74 (Exp. 1 and 2) and d 154 (Exp. 2). Each heifer was palpated rectally for pregnancy at the end of each experiment. Pregnancy rates were higher (P < .01) for control heifers (0 mg implant) than for heifers that received 24, 36, or 48 mg of norgestomet. In Exp. 1, pregnancy rates were 96, 29, 6, and 4% for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. In Exp. 2, pregnancy rates were 85, 36, 19, and 9% for heifers that received 0, 24, 36, and 48 mg implants of norgestomet, respectively. Estrous activity during the first 3 wk of bull exposure was reduced (P < .05) among heifers that received norgestomet implants compared to control heifers but was not completely abolished at any dosage in Exp. 1. During the first 75 d of Exp. 1 and 2, heifers treated with 36 or 48 mg norgestomet implants gained weight faster (P < .05) than control heifers. Combined across both experiments, ADG during the first 74 d were .53, .56, .59, and .60 kg/d for heifers treated with 0, 24, 36, and 48 mg implants of norgestomet, respectively. These data indicate that norgestomet implants increased rate of weight gain, reduced estrous activity, and reduced the occurrence of pregnancy in heifers on pasture.

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