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Titolo:
Effect of short-term calf removal at three stages of a follicular wave on fate of a dominant follicle in postpartum beef cows
Autore:
Salfen, BE; Kojima, FN; Bader, JF; Smith, MF; Garverick, HA;
Indirizzi:
Univ Missouri, Dept Anim Sci 163, Columbia, MO 65211 USA Univ Missouri Columbia MO USA 65211 Anim Sci 163, Columbia, MO 65211 USA
Titolo Testata:
JOURNAL OF ANIMAL SCIENCE
fascicolo: 10, volume: 79, anno: 2001,
pagine: 2688 - 2697
SICI:
0021-8812(200110)79:10<2688:EOSCRA>2.0.ZU;2-T
Fonte:
ISI
Lingua:
ENG
Soggetto:
GROWTH-FACTOR-I; GONADOTROPIN-RELEASING-HORMONE; BOVINE OVARIAN FOLLICLES; LUTEINIZING-HORMONE; REPRODUCTIVE HORMONES; STIMULATING-HORMONE; ESTRADIOL BENZOATE; ENDOCRINE CHANGES; BINDING-PROTEINS; DAIRY-COWS;
Keywords:
beef cattle; calf removal; graafian follicles; ovulation; suckling;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Citazioni:
45
Recensione:
Indirizzi per estratti:
Indirizzo: Garverick, HA Univ Missouri, Dept Anim Sci 163, Columbia, MO 65211 USA Univ Missouri Columbia MO USA 65211 Columbia, MO 65211 USA
Citazione:
B.E. Salfen et al., "Effect of short-term calf removal at three stages of a follicular wave on fate of a dominant follicle in postpartum beef cows", J ANIM SCI, 79(10), 2001, pp. 2688-2697

Abstract

The hypothesis that ovulation in response to short-term (48 h) calf removal (CR) is dependent on the developmental stage of the dominant follicle wastested in two studies. The objective of Exp. 1 was to characterize the fate of a dominant follicle following 48-h CR on d 2, 4, or 8 of a postpartum follicular wave. Ovaries of 61 beef cows were examined daily by transrectalultrasonography starting at d 20 to 21 postpartum. Treatments were no CR (n = 14) and CR on d 2 (n = 12), 4 (n = 16), or 8 (n = 10) of first detectedfollicular wave. Percentage of cows that ovulated a dominant follicle following treatment was not different among groups (P = 0.62). Maximum size of dominant follicles was larger in cows that ovulated (P = 0.002) than in cows that did not ovulate. The objectives of Exp. 2 were 1) to determine whether a follicular wave could be synchronized in anestrous cows following injection of 1 mg of estradiol benzoate (EB) and 200 mg of progesterone (P-4; EB + P-4); 2) to characterize the fate of dominant follicles following 48-h CR at three stages of a synchronized follicular wave; and 3) to determine whether estrous cycles of normal length followed ovulation in cows pretreated with EB + P-4. Ovaries of 50 anestrous beef cows were examined daily as in Exp. 1. Treatments were sesame oil (SO) injected (i.m.) on d 25 postpartum and no CR (n = 9); EB + P-4 and no CR (n = 9); EB + P-4 and CR on 6 (n = 12), 8 (n = 9), or 12 (n = 11) d after injection. The EB and P-4 injectionswere given on d 25 postpartum. Variability in day of emergence of subsequent follicular waves was lower in cows receiving EB + P-4 than in SO-injected cows (P < 0.05). The percentage of cows that ovulated was not different (P = 0.16), but CR increased the percentage of cows that ovulated when groups that received EB + P-4 were compared to the EB + P-4 group that did not have CR (53.1 vs 11.1%, respectively; P < 0.05). Maximum diameter of dominant follicles was larger (P = 0.05) in ovulatory follicles. The luteal phase was longer (P < 0.03) in cows receiving EB + P-4 injection (10.6 +/- 1.2 d)than in cows receiving SO (4.4 +/- 2.2 d). In summary, the maximum size ofovulatory follicles was greater than that of nonovulatory follicles, the ovulatory response of postpartum anestrous cows was maintained through d 8 of a follicular wave, synchronization of follicular waves was accomplished in postpartum cows using EB + P-4, and the subsequent luteal phase length was increased in animals that were administered EB + P-4.

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Documento generato il 20/09/20 alle ore 07:48:09