Comparison of long-term progestin-based protocols to synchronize estrus in beef heifers

2009 ◽  
Author(s):  
Daniel A. Mallory
Keyword(s):  
Beef Heifers

Effects of long-term estrogen implants in beef heifers.

1999 ◽  
Vol 77 (11) ◽  
pp. 2886 ◽  
Author(s):  
D M Kniffen ◽  
W R Wagner ◽  
P E Lewis
Keyword(s):  
Beef Heifers ◽  
Estrogen Implants

Comparison of long-term CIDR-based protocols to synchronize estrus in beef heifers

2009 ◽  
Vol 114 (4) ◽  
pp. 345-355 ◽  
Author(s):  
N.R. Leitman ◽  
D.C. Busch ◽  
D.A. Mallory ◽  
D.J. Wilson ◽  
M.R. Ellersieck ◽  
...  
Keyword(s):  
Beef Heifers

scholarly journals Evaluation of pre-breeding reproductive tract scoring as a predictor of long term reproductive performance in beef heifers

2015 ◽  
Vol 118 (1) ◽  
pp. 56-63 ◽  
Author(s):  
D.E. Holm ◽  
M. Nielen ◽  
R. Jorritsma ◽  
P.C. Irons ◽  
P.N. Thompson
Keyword(s):  
Reproductive Performance ◽  
Reproductive Tract ◽  
Beef Heifers

scholarly journals Effects of prolonging the interval from progestin removal to prostaglandin F2α injection from 16 to 17 days in a long-term estrus synchronization protocol in beef heifers

2021 ◽  
Author(s):  
N Oosthuizen ◽  
G D Melo ◽  
G E Seidel ◽  
R L Stewart ◽  
L Rowden ◽  
...  
Keyword(s):  
Prostaglandin F2α ◽  
Fixed Time ◽  
Transrectal Ultrasonography ◽  
Dominant Follicle ◽  
Beef Heifers ◽  
Treatment Groups ◽  
Follicle Diameter ◽  
Randomized Design ◽  
Angus Heifers

Abstract To determine effects of delaying the injection of prostaglandin F2α (PGF) and fixed-time artificial insemination (TAI) in the 14-d CIDR-PG protocol, 1,049 Angus heifers at six locations were enrolled in a completely randomized design. Within location heifers were randomly assigned to one of two treatment groups: 1) PG16 (n = 518), heifers received a controlled internal drug release (CIDR) insert on d 0 for 14 d, a 25-mg injection of PGF 16 d after CIDR removal (Day 30), and a 100-µg injection of gonadotropin-releasing hormone concurrent with TAI 66 ± 2 h later; or 2) PG17 (n = 531), heifers were treated the same as PG16, however, PGF was administered 17 d after CIDR removal (Day 31), and heifers were TAI 66 ± 2 h later. Estrus detection patches were applied to a subset (n = 482) of heifers at the time of PGF administration and were examined for activation at TAI. Dominant follicle diameter was determined via transrectal ultrasonography at PGF administration and TAI in a subset of heifers (n = 116). Transrectal ultrasonography was performed to determine pregnancy rates to TAI (PR/AI) between 30 and 45 d after TAI. Estrus expression prior to TAI differed by treatment where PG17 heifers had greater (P < 0.01) expression of estrus than PG16 heifers (57.8 ± 6.1 vs. 43.4 ± 6.1%, respectively). Nevertheless, dominant follicle diameters at PGF and at TAI were similar (P ≥ 0.59) between PG16 and PG17 heifers. In addition, PR/AI did not differ (P = 0.29) between PG16 and PG17 treatments (50.5 ± 3.2 vs. 45.7 ± 3.1%, respectively). Results of this experiment indicate that delaying the injection of PGF and TAI in the 14-day CIDR-PG protocol increased estrus expression prior to TAI yet did not improve fertility in beef heifers.

Effect of degree of fatness in yearling replacement beef heifers on lifetime performance

1993 ◽  
Vol 73 (2) ◽  
pp. 295-301
Author(s):  
L. F. Laflamme
Keyword(s):  
Key Words ◽  
Term Effect ◽  
Beef Heifers ◽  
High Group ◽  
Lifetime Performance ◽  
Long Term Effect ◽  
Kg Medium

A study was initiated to determine the long-term effect of weight and age at breeding in yearling beef heifers on lifetime performance. Thirty weaned replacement heifers in each of 3 yr were equally fed until breeding on one of three systems: (i) gain of 1 kg d−1 and bred at 350 kg (medium); (ii) gain of 1 kg d−1 and bred at 15 mo of age (high); or (iii) bred at 350 kg and 15 mo of age (low). The high group had an advantage (P < 0.05) in the number of calves produced or weaned, suggesting a greater persistency of production; however, the low group weaned heavier calves. The rearing treatments had no effect (P > 0.05) on the heifer mature weights or on the birth weights of the calves. Most of the differences detected were in the first 5 yr, at which time 50% of the heifers had already been culled. Key words: Beef heifers, rearing, lifetime performance

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