Considerations Related to Heifer Management. Heifer Management CONTROL OF ESTRUS IN HEIFERS

Transcription

1 Considerations Related to Heifer Management CONTROL OF ESTRUS IN HEIFERS DJ Patterson, NT Martin, JM Thomas, and MF Smith Division of Animal Sciences University of Missouri Heifer Management Effect of calving date on the number of cows calving the subsequent year Heifers that conceive earlier during their first breeding season Stay in the herd longer Produce more pounds of beef over their lifetime Cows failing to calve (%) d 1- d 21- d 41-6 d 61-8 d 81- d Day of calving season (Burris and Priode, 198) Relationship between time of calving and lifetime production of beef cows Reproductive management prior to the first breeding season Early Late Average lifetime weaning weight (kg) 1. Target weight 2. Reproductive tract scores (RTS) 3. Pelvic measurements 4. Estrous synchronization. Sire selection (BW or CE EPD) Adapted from Lesmeister et al.,

2 Reproductive management prior to the first breeding season 1. Target weight 2. Reproductive tract scores 3. Pelvic measurements 4. Estrous synchronization. Sire selection (BW or CE EPD) Accuracies make a difference Prebreeding evaluation of heifers Weight Reproductive tract scores Pelvic area Reproductive Tract Scores Endocrine and Ovarian Changes Associated with Puberty Onset Uterine RTS Horns Immature, < mm diameter, 1 no tone -2 mm diameter, 2 no tone -2 mm diameter, 3 slight tone 4 mm diameter, good tone Ovarian Length (mm) Ovarian Height (mm) Ovarian Width (mm) 1 8 Ovarian Structures No palpable follicles mm follicles mm follicles > mm follicles, Cl possible Estradiol secretion Estradiol feedback LH secretion Prepubertal Peripubertal Pubertal + > mm diameter >32 1 Corpus luteum present Follicle diameter Reproductive tract score From Anderson et al., 1991 Adapted from Day and Anderson,1998; Anderson et al., Infantile Reproductive Tract Score (RTS) Summary RTS 2 prepubertal (> d from puberty) 3 prepubertal 1,3 (< d from puberty) 4 cycling (follicular phase) cycling (luteal phase) n Pelvic Height Weight (lb) (cm) 697 c 94 a 6 b 733 d 7 d 13.9 a 14.1 a 14. b 14.7 c 14.7 c Pelvic Width (cm).9 a 11.2 a 11.4 b 11.7 c 11.7 c Pelvic Area (cm 2 ) 12 a 18 a 166 b 172 c 172 c a, b, c, d Numbers with different superscripts within a column differ (P <.) Patterson and Bullock, Estrous Response (%) 4 a 66 b 76 c 83 d 86 d SHOW-ME-SELECT REPLACEMENT HEIFER PROGRAM RTS and FT pregnancy rate for,126 heifers Spring - Fall 11 RTS n ,71 1,3 1,816 FT PR.% 36.% 48.% 2.1% 9.4% Thomas et al., 12 2

3 Neonatal exposure to progesterone and estradiol on reproductive tract in beef heifers Heifer Management Age at b Response a Birth Day 21 Day 4 Control Uterocervical weight c (g) d 123. d 1.3 d e Myometrial area (mm 2 ) g g g h Endometrial area (mm 2 ) 29.9 i 32.4 i 37.7 i 4.4 j Gland Density (hits/mm 2 ) d 38.3 e e f Uterine luminal protein (mg/flush) 2.8 d 2.9 d 2.3 d 4.9 e RTS: 4 to 6 weeks before breeding or 2 weeks before estrous synchronization Begin synchronization when % of the heifers have RTS of 4 or From Bartol et al., 199 Why use estrous synchronization? Why use estrous synchronization? More heifers will become pregnant early during the breeding season Progestin-based programs can induce estrous cyclicity in pre- or peripubertal heifers (MGA, or CIDR) Pregnancy rates of heifers in natural service versus synchronized and ed herds RTS Total Exposed NS 1 (n) S 2 (n) , , 21-d pregnancy rate NS (%) S (%) 38 a 31 a 41 a 48 a a 44 a 1, 2 NS=natural service; S= synchronized and ed a, b P<. Adapted from Randle and Patterson, 42 a 2 b 8 b 62 b 64 b 61 b % Reasons Beef Producers in the U.S. Cite for not Using Reproductive Procedures Estrus synchronization Artificial insemination Pregnancy diagnosis Time/labor Cost Complicated Other From NAHMS Survey, 8 3

4 MGA-Based Protocols for Heifers was the preferred method of estrus synchronization in beef heifers (Brown et al., 1986; Deutscher et al., ; Lamb et al., ). MGA 17 to 19 days 1 14 day 33 MGA prior to Natural Service or prior to MGA (14 days) Sub-fertile estrus days Natural service Breeding program Natural service No. heifers Estrous response Synchronized conception rate Synchronized pregnancy rate / % /424 79% 2414/334 72% 2414/424 7% % of herd in estrus Considerations pertaining to long-term MGA feeding () MGA (Natural service) 4

5 Estrous Response Experimental Design MGA (14 days) MGA (87 days) Estrus Response (%) /31 77 % 16/ 3 % 4/7 7 % /14 71 % 28/31 9 % 26/ 87 % days 1st injection 2nd injection Short-term MGA Total Long-term MGA Patterson et al., 1992 Ovarian Morphology Normal Abnormal Short-term MGA 31/31 % /31 %* Long-term MGA 19/ 63 % 11/ 37 %* Abnormal = Luteinized follicular cyst * P <.1

6 Conception Rate Pregnancy Rate Conception Rate (%) /24 7 % 12/16 7 % 3/4 7 % 6/ 6 % 21/28 7 % 1 st injection 2 nd injection Total Short-term MGA 18/26 69 % Long-term MGA Pregnancy Rate (%) /31 9 % Short-term MGA 27/ 9 % Long-term MGA s How do MGA- and CIDR-based protocols compare in heifers? MGA days Heat detection and CIDR days 36 Heat detection and Mallory, et al., 9 Estrous distribution after MGA or CIDR Estrus, % NR Interval after progestin removal, treatment d Mean interval to estrus and variance for interval to estrus after MGA or CIDR Overall mean interval to estrus, h 14-day CIDR ± 12.6 a 37.8 ± 11.2 b Estrus, % 14-day CIDR- Variance for interval to estrus 9172 a 136 b a,b Means within rows with different superscripts differ (P <.1) NR Interval after progestin removal, treatment d Mallory, et al., 9 6

7 Estrous response after Distribution of estrus after 14-day CIDR- Overall estrous response 17/ 18/196 8 a 92 b day CIDR- Estrous cycling 13/14 138/11 88 x 91 2 Prepubertal 3/46 42/4 76 c,y 93 d a,b Means within rows with different superscripts differ (P =.1) c,d Means within rows with different superscripts differ (P =.3) x,y Means within rows with different superscripts tend to differ (P =.6) Estrus, % NR Mallory, et al., 9 Interval after administration, h Mean interval to estrus and variance for interval to estrus after Overall mean interval to estrus, h Variance for interval to estrus after 14-day CIDR- 7.4 ± ± a 282 b a,b Means within rows with different superscripts differ (P =.1) Conclusion Estrous response (P =.1) and synchrony of estrus (P <.1) were significantly improved among heifers assigned to the 14- day CIDR- protocol. Pre-synchronization with a 14-d CIDR followed 16 d later with provides an effective alternative for use in synchronizing estrus in replacement beef heifers. There were no differences between treatments for synchronized conception or pregnancy rates. Mallory, et al., 9 Mallory, et al., 9 The Multi-State CIDR Trial h Detect estrus & h Detect estrus & Lamb et al., h FT h FT Lamb et al., 6 7

8 Estrus 233/383 61% Estrus 236/372 63% FT /133 37% 282/16 % FT 1/131 39% 289/3 7% Multi-state CIDR Trial at CIDR insertion did not improve pregnancy rates after FT h Detect estrus & FT 29/2 49% h Detect estrus & FT 282/31 3% at CIDR insertion did not alter the percentage of heifers detected in estrus or the distribution of estrus after A combination of detecting estrus and before cleanup enhanced pregnancy rates over FT h h Lamb et al., 6 CO-Synch + CIDR w/ T at 4h vs w/ T at 72h How do long- and short-term CIDR-based protocols compare in heifers? CO-Synch + CIDR h CIDR (14 days) days days h day Busch et al., 7 CO-Synch + CIDR Total Diff. pregnancy Fixed-time pregnancy rate Pre/peripubertal 13/21 (62%) 11/23 (48%) 24/44 (%) + 14 % Estrous cycling 4/87 (62%) x /86 (47%) y 94/173 (4%) + 1 % x,y P=.3 Busch et al., 7 Combined 67/8 (62%) x 1/9 (47%) y 118/217 (4%) + 1 % x,y P=.2 vs CO-Synch + CIDR Synchronizing beef heifers with the protocol resulted in: Increased response to (P =.1) Higher estrous response (P =.6) Reduced variance associated with the interval from to estrus and ovulation (P <.1) Significantly higher FT pregnancy rates (P =.2) = 62% CO-Synch + CIDR = 47% Reduced variance associated with the interval from FT to the subsequent return to estrus (P <.) Busch et al., 7; Leitman et al., 8 8

9 How do the and 14-day CIDR- protocols compare? How do the and 14-day CIDR- protocols compare? Estrous response Interval to and synchrony of estrus Synchronized pregnancy rate Leitman et al., 9 s Distribution of estrus after CIDR d d day CIDR- CIDR d Estrus, % day CIDR NR Interval after administration, h Leitman et al., 9 Leitman et al., 9 14-day CIDR- vs. Estrous response was similar between treatments (98%, 14-day CIDR-; 94%, ; P =.43) Mean interval to estrus was 7 h earlier (P =.1) for 14-day CIDR- treated heifers compared to CIDR Select treated heifers Heifers assigned to 14-day CIDR- had a greater (P <.1) synchrony of estrus compared to heifers assigned to Pregnancy results 14- day CIDR- conception rate 78/13 (8) x 92/137 (67) y pregnancy rate 78/143 () a 92/1 (66) b Final pregnancy rate 116/143 (81) 113/1 (81) x,y Means within rows with different superscripts tend to differ (P =.9) a,b Means within rows with different superscripts differ (P =.) Leitman et al., 9 9

10 Conclusion The administration of following CIDR removal in the protocol is not required to facilitate an improvement in the synchrony of estrus in beef heifers. How do the and 14-day CIDR- protocols compare on the basis of pregnancy rates resulting from fixed-time? Leitman et al., 9 s Combined Estrus Distribution 14-day CIDR- 4 Leitman et al. (9a) Leitman et al. (9b) CIDR 9 days 7 days 3 Mallory et al. (9) n = 424 heifers hr 2 14-day CIDR- 1 CIDR days 66 hr NR Mallory et al., 11 n = 424 heifers on HeatWatch Fixed-time pregnancy rates Summary pregnancy rate Estrous cycling Prepubertal 14-day CIDR- 98/ / 1 a 62 b 83/18 2/162 3 c 63 d 1/ /38 8 Pregnancy rates tended to be higher (P =.7) for 14-day CIDR- compared to CIDR Select treated heifers. Final pregnancy rates did not differ between treatments. a,b Means within rows with different superscripts tend to differ (P =.7) c,d Means within rows with different superscripts tend to differ (P =.6) Mallory et al., 11 Mallory et al., 11

11 Conclusion 14-day CIDR- is effective in synchronizing estrus prior to FT in beef heifers. Leitman et al. (9a,b) Mallory et al. (9a) Heat detection Mallory et al. (9b) --- Cooperating herds (KS, MO, MT) --- Totals Fixed-time 241/422 7% /422 7% 124/ 62% 16/246 6% 1729/266 6% 14-d CIDR- protocol for heifers CIDR hr day Combining health & reproduction in a single management step. 6-day CIDR 6-day CIDR CIDR (6 d) h Summary & Conclusions Comparison of estrous response and fertility in beef heifers after treatment with various estrus synchronization protocols. Synchronized pregnancy Estrous response rate based on detected estrus d MGA Select CIDR- (d6) 14-day CIDR- 1129/12 433/499 /28 896/ /422 87% 87% 7% 92% 93% 768/12 28/ /8 77/ /422 9% 6% 39% 9% 7% Heat detect & fixed-time 7-day CIDR-: 84 hr Select Synch + CIDR: 84 hr 14 d CIDR-: 72 hr 14 d MGA + : 72hr performed at predetermined fixed times with no estrus detection 7-day CIDR- CO-Synch + CIDR CO-Synch + CIDR 14-day CIDR- 6 hr 6 hr 4 hr 72 hr 66 hr 282/17 % 289/4 7% 48/77 62% 2/79 66% 28/2 49% 282/31 3% 1/9 47% 616/1 8% 1729/266 6% 11

12 Take Home Points Long-term CIDR-based protocols enhance synchrony of estrus in estrous cycling and preor peripubertal heifers compared to short-term CIDR-based or MGA-based protocols. Acknowledgements Pregnancy rates resulting from fixed-time in beef heifers are expected to be higher following treatment with long-term CIDRbased protocols because of improvements in synchrony of estrus following treatment. Acknowledgements Faculty, Students, & Staff Faculty Regional Extension Livestock Specialists Mike Smith Roger Eakins Matthew Lucy Mark Ellersieck Students MU Farms & Centers Jon Bader David McAtee Nicole Leitman Jon Schreffler Daniel Mallory Stoney Coffman Neal Martin Dennis Hamilton Justin Nash Randall Smoot Daniel Schafer Jacob Stegner Jordan Thomas Dallas Wilson Stacey Wood (Follis) Research Specialists & Postdoctoral Fellows Dan Busch Naoto (Freddie) Kojima Acknowledgements Financial Support Acknowledgements Product support Pfizer Merial TEVA Semen Support ABS Global Acclerated Genetics Genex Select Sires, Inc. Acknowledgements Cooperators Circle A Angus 4-M Ranch MFA, Inc. MU Thompson Research Center Genex (Stan Lock) 12