88 Impacts of Body Condition Score at Initiation of the Breeding Season on Reproductive Performance and Overall Productivity of Bos Taurus and B. Indicus Beef Cows

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 48-48
Author(s):  
Alice Brandão ◽  
Reinaldo F Cooke ◽  
G Cliff C Lamb ◽  
José Luiz Vasconcelos ◽  
Ky G Pohler
Keyword(s):  
Breeding Season ◽  
Body Condition ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Condition Score ◽  
Pregnancy Status ◽  
Calving Rate ◽  
Natural Service

Abstract Responses of Bos taurus (BT) and B. indicus (BI) beef cows were compared according to their body condition score (BCS) at initiation of breeding season. Cows were assigned to an estrus synchronization + AI protocol and classified as BCS < 5.0 (LBCS, BT, n = 158; BI, n = 248) or BCS ≥ 5.0 (HBCS; BT, n = 173; BI, n = 122). Pregnancy status was verified via transrectal ultrasonography at 30 and 40 d after AI for BI and BT cows, respectively. All BT cows were exposed to natural service for 50 d (beginning 18 d after AI), and all non-pregnant BI cows were immediately exposed to natural service for 60 d. Pregnancy rates to AI did not differ (P ≥ 0.16) between HBCS or LBCS cows (60.9 vs. 53.5% for BT; 37.0 vs. 31.4% for BI; respectively). Pregnancy rates to natural service were greater (P = 0.03) in HBCS BT cows compared with LBCS (82.7 vs. 67.9%; respectively) but did not differ in BI cows (78.9 vs. 71.5%; respectively). Calving rate was greater (P < 0.03) in HBCS cows, which also calved earlier (P < 0.01) compared with LBCS (93.7 vs. 85.1% in BT, 83.6 vs. 73.3% in BI; respectively). HBCS Cows weaned more (P ≤ 0.05) calves compared with LBCS, which were older (P ≤ 0.04) (215 vs. 211 d in BT, 219 vs. 209 d in BI; respectively) and heavier (P ≤ 0.09) at weaning (258 vs. 252 kg in BT, 213 vs. 203 d in BI; respectively). Lastly, kg of calf weaned/cow was greater (P ≤ 0.03) in HBCS cows compared with LBCS (221 vs. 200 d in BT, 159 vs. 129 d in BI; respectively). Therefore, HBCS cows had greater reproductive efficiency and overall productivity, and this was observed in both BT and BI.

scholarly journals 166 EFFECT OF TREATMENT WITH hCG OR GnRH AT THE TIME OF EMBRYO TRANSFER ON PREGNANCY RATES IN COWS SYNCHRONIZED WITH PROGESTERONE VAGINAL DEVICES, ESTRADIOL BENZOATE, AND eCG

2005 ◽  
Vol 17 (2) ◽  
pp. 234 ◽  
Author(s):  
R. Tribulo ◽  
E. Balla ◽  
L. Cutaia ◽  
G.A. Bo ◽  
P.S. Baruselli ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Condition Score ◽  
Pregnancy Status ◽  
To Receive

Although several studies have investigated the relationship between circulating progesterone and pregnancy rates in cattle, the beneficial effect of treatments that increase progesterone concentrations, by insertion of a progesterone (P4) releasing device or induction of an accessory CL with hCG, GnRH, or LH treatment, has resulted in inconsistent effects on pregnancy rates in embryo recipients. An experiment was designed to evaluate the effect of hCG or GnRH treatment, given at the time of embryo transfer without estrus detection, on pregnancy rates in recipients treated with intrauterine P4-releasing devices, estradiol benzoate (EB), and eCG. The experiment was performed in two replicates; non-lactating Bos taurus × Bos indicus crossbred beef cows with a body condition score between 2.5 to 3.5 (1-to-5 scale) were used (replicate 1, n = 180; replicate 2, n = 140). All cows received 1 g of P4 via a P4-releasing device (DIB, Syntex, Argentina) and 2 mg EB i.m. (Syntex) on Day 0, and 400 IU of eCG i.m. (Novormon 5000, Syntex) plus 150 μg d(+)cloprostenol i.m. (Ciclase, Syntex) on Day 5. DIBs were removed on Day 8 and all cows received 1 mg EB i.m. on Day 9. Recipients were not observed for signs of estrus, and those >1 CL, or a single CL with an area >256 mm2, received 195 Grade 1 and 46 Grade 2 frozen/thawed “direct transfer” embryos on Day 17. At the time of embryo transfer, recipients were randomly allocated to 1 of 3 treatment groups to receive 1500 IU hCG (Ovusyn, Syntex), 50 μg Lecirelina (GnRH, Gonasyn, Syntex), or no treatment (control) at that time. Ovarian ultrasonography was performed on Day 0 to determine ovarian status (only cows with a CL or a follicle >10 mm and uterine tone were used), on Day 17 to measure CL area, and 40 days after embryo transfer to determine pregnancy status. Data were analyzed by logistic regression and the effects of replication, technician, treatment, and embryo quality were considered in the model. From the 320 recipients treated with a DIB plus EB and eCG, 241 (75.3%) were selected to receive an embryo. Nine (3.7%) and 1 (0.4%) of the selected recipients had 2 and 3 CL, respectively. Pregnancy rates did not differ between replicates (replicate 1: 80/140, 57.1%; and replicate 2: 57/101, 56.4%; P = 0.84), technicians (technician 1: 65/118, 55.1%; and technician 2: 72/123, 58.5%; P = 0.64), or treatments (hCG: 43/80, 53.8%; GnRH: 45/83, 54.2%; and control: 49/78, 62.8% P = 0.99). However, pregnancy rates were higher (P = 0.001) in recipients receiving Grade 1 embryos (121/195, 62.1%) than in those receiving Grade 2 embryos (16/46, 34.8%). GnRH or hCG treatment at the time of embryo transfer did not increase pregnancy rates in recipients synchronized with P4 releasing devices, EB, and eCG. Research was supported by Syntex S.A., Estancia El Mangrullo S.A., and Agencia Cordoba Ciencia S.E.

20 PREGNANCY RATES IN SUCKLED BEEF COWS SYNCHRONIZED WITH PROGESTERONE INTRAVAGINAL DEVICES AND RECEIVING eCG FOURTEEN DAYS AFTER BREEDING

2010 ◽  
Vol 22 (1) ◽  
pp. 168 ◽  
Author(s):  
L. Cutaia ◽  
M. Ramos ◽  
P. Chesta ◽  
G. A. Bó
Keyword(s):  
Body Condition ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Beef Cows ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Treatment Groups ◽  
Condition Score

An experiment was designed to test the following hypotheses: (1) the administration of 400IU of eCG (Novormón, Syntex SA, Buenos Aires, Argentina) 14 days after fixed-time artificial insemination (FTAI) increases pregnancy rates in cross-breed Zebu × Bonsmara suckled cows synchronized with progesterone releasing devices (DIB 0.5, 0.5 g of progesterone, Syntex SA); and (2) pregnancy rates in cows treated with estradiol or GnRH, combined with a DIB device, are not different. Primiparous suckled cows (n = 260), between 60 and 120 days postpartum (DPP) and with a body condition score between 2.0 and 2.5 (1 to 5 scale) were used. At the beginning of the experiment (Day 0), all cows were examined by rectal palpation (only 11% had a CL), received a DIB device, and were randomly allocated to 1 of 3 treatment groups. Cows in the E2 group received 2 mg of estradiol benzoate (EB) intramuscularly (i.m.) at DIB insertion and those in the two GnRH groups received 100 μg of gonadorelin (GDR Gonasyn, Syntex SA) at the same time. On Day 7, DIB devices were removed and all cows received 500 μg of cloprostenol (Ciclase DL, Syntex SA) plus 400 IU of eCG (i.m.). Cows in the E2 group received 0.5 mg of estradiol cypionate (ECP, Cipiosyn, Syntex SA) and underwent FTAI administered by one technician, using semen from 1 of 2 bulls between 52 and 56 h later. Cows in the GnRH groups received a dose of 100 μg of gonadorelin (full GnRH group) or 50 μg of gonadorelin (1/2 GnRH group) at the time of the FTAI (52 to 56 h after DIB removal). Fourteen days after FTAI cows in the 3 groups were further subdivided (3 × 2 factorial) to receive or not 400 IU of eCG i.m. Pregnancy was determined 30 days after FTAI using real-time ultrasonography. Data were analyzed by logistic regression, taking into account the effect of the synchronization treatment, eCG or noteCG, 14 days after FTAI and sire used. No differences in pregnancy rates were found (P = 0.16) among treatment groups (E2: 39/87, 43.7%, full GnRH: 38/92, 41.3%, and 1/2 GnRH: 25/81, 30.9%). However, there was a significant (P = 0.02) effect of eCG treatment 14 days after FTAI (eCG: 60/127, 47.2% v. no eCG: 41/133, 30.8%). Furthermore, bull A (77/155, 47.1%) resulted in higher pregnancy rate (P = 0.009) than bull B (28/107, 26.2%), but there were no significant interactions between bull and synchronization treatment or eCG administration 14 days after FTAI (P > 0.1). We conclude that the application of 400 IU of eCG 14 days after FTAI increases pregnancy rates in suckled Bos taurus × Bos indicus primiparous cows with fair to poor body condition score synchronized with progesterone releasing devices. Furthermore, the use of estradiol ester or GnRH at DIB insertion and removal did not affect pregnancy rates.

20 ADMINISTRATION OF FOLLICLE-STIMULATING HORMONE AT CIDR REMOVAL DOES NOT AFFECT THE PREGNANCY RATE IN A CIDR-BASED, COSYNCH PROTOCOL IN LACTATING BEEF COWS

2008 ◽  
Vol 20 (1) ◽  
pp. 90 ◽  
Author(s):  
J. Small ◽  
F. Dias ◽  
L. Pfeifer ◽  
K. Lightfoot ◽  
M. Colazo ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Pregnancy Rate ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Animal Health ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Condition Score ◽  
Secondary Objective ◽  
Pfizer Animal Health

In previous studies, giving eCG at CIDR removal significantly increased the pregnancy rate after timed-AI in beef cows. However, eCG is not universally available. Therefore, we tested the hypothesis that giving pFSH at CIDR removal might improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows; a secondary objective was to compare pregnancy rates when GnRH v. pLH was used to synchronize wave emergence and ovulation. This work was conducted as two experiments (separate locations). All cows were given a CIDR (containing 1.9 g progesterone; Pfizer Animal Health, Montreal, QC, Canada) on Day 0 (without regard to stage of estrous cycle or cyclicity). On Day 7, CIDRs were removed, all cows were concurrently given 25 mg PGF (Lutalyse; Pfizer Animal Health, Groton, CT, USA), half were given 20 mg pFSH (Folltropin-V; Bioniche Animal Health, Belleville, ON, Canada), and all cows were timed-AI 54 h later (Day 9). In Experiment 1, 240 cows [94 � 10.8 days postpartum; body condition score (BCS: 1 = emaciated, 9 = obese; mean � SD): 5.8 � 0.4] were used; at CIDR insertion and AI, cows were allocated to receive either 100 µg GnRH (n = 160; Cystorelin, Merial Canada Inc., Victoriaville, QC, Canada) or 12.5 mg pLH (n = 80; Lutropin-V, Bioniche Animal Health). In Experiment 2, 109 cows (59.2 � 19.5 days postpartum; BCS: 5.6 � 1.1) were used; all received 100 µg GnRH (Cystorelin) at CIDR insertion and AI. In Experiment 1, three cows that lost their CIDR were excluded; pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, synchronizing treatment, and their interactions) were not different between cows given pFSH v. control cows (64.7 v. 65.2%; P > 0.80), nor between cows given GnRH v. pLH (62.7 v. 69.6%; P = 0.91). However, there was an interaction (P < 0.04) between parity and the synchronizing treatment; in primiparous cows, pregnancy rates were significantly lower in those given GnRH v. pLH (59.3 v. 83.3%). In Experiment 2, pregnancy rates after timed-AI (logistic regression, backward selection: parity, pFSH, and their interaction) were not different between cows given pFSH v. control cows (38.2 v. 42.6%; P > 0.6). In conclusion, our hypothesis was not supported; giving pFSH at CIDR removal did not significantly improve the pregnancy rate in a CIDR-based, Cosynch protocol in postpartum, suckled Bos taurus beef cows.

scholarly journals 185 Strategies for managing open beef cows

2019 ◽  
Vol 97 (Supplement_1) ◽  
pp. 63-63
Author(s):  
Stephen M Lira ◽  
Jon T Biermacher ◽  
Evan Whitley ◽  
Devlon Ford
Keyword(s):  
Body Condition ◽  
Fixed Effects ◽  
Body Condition Score ◽  
Beef Cows ◽  
Mixed Effects ◽  
Individual Animal ◽  
Net Return ◽  
South Central ◽  
Condition Score ◽  
Pregnancy Status

Abstract Open beef cows account for between 15 and 30% of a spring-calving cow/calf operation’s annual revenue; however, most producers commonly sell open cows at weaning when prices are at a seasonal low. A three-year (2015–2018) study was conducted using open beef cows (n = 244) from a spring-calving herd in south-central Oklahoma. The objective of the study was to determine whether or not the net return of retaining, feeding, rebreeding, and marketing rebred cows was greater than the revenue from selling open cows at weaning. Each year at weaning, open cows were sorted into Thin or Moderate groups using an average threeman Body Condition Score (BCS). Thin cows (BCS < 5.5) received a ration of 11.4% CP and 63.9% TDN, while Moderate cows (5.5 ≤ BCS ≤ 6.0) received 10.4% CP and 55.2% TDN. Rations were formulated to transform the final condition of all cattle to a BCS of 6. Two rested bulls were assigned to each feeding group during the first 60 days of retention. After 90 days of retention all cattle were pregnancy tested via ultrasound. Enterprise budgeting techniques were used to calculate revenue, costs, and net return for each cow. Mixed effects (ANOVA) models using the Mixed Procedure in SAS were used to determine the fixed effects of feeding treatment, age, pregnancy status, and market type on ending weight and BCS and net return. Year and individual animal were tested and treated as random for each model analyzed. On average, net return was affected by feeding treatment (P = 0.0323), age (P < 0.0001), and pregnancy status (P < 0.0001). The results suggest that producers who have the ability to sort and feed young, thin cows in poorer condition and rebreed them using rested bulls can expect to earn $68/head more than selling them as open at weaning

Setting the Cycle for Reproductive Success with a Pre-synchronization Program in Postpartum Beef Cows

2021 ◽  
Vol 99 (Supplement_2) ◽  
pp. 23-23
Author(s):  
Macy M Massengill ◽  
Thiago V Silva ◽  
Daniel H Poole
Keyword(s):  
Body Condition Score ◽  
Statistical Significance ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Estrous Synchronization ◽  
Condition Score ◽  
Pregnancy Status ◽  
Timed Artificial Insemination ◽  
To Receive ◽  
Synchronization Protocol

Abstract Previous experiments from our laboratory determined that postpartum beef cows with a functional corpus luteum (CL) at the start of an estrous synchronization protocol have greater pregnancy success to FTAI than those that did not have a CL. Therefore, it was hypothesized that incorporation a presynchronization program prior to FTAI in postpartum cows will improve pregnancy rates. The goal of this project was to compare the effectiveness of a presynchronization program prior to the 7-d CO-Synch+CIDR fixed timed artificial insemination (FTAI) protocol in postpartum cows. Postpartum cows (n = 310) at two locations were randomly assigned to receive either the presynchronization program, consisting of 2 PGF2α injections 14 d apart and 11 d prior to the start of the 7-d CO-Synch+CIDR protocol, or the 7-d CO-Synch + CIDR protocol. Following estrus synchronization, all cows were inseminated by trained technicians using semen from bulls of known fertility. Pregnancy status to FTAI was assessed using ultrasonographic diagnosis at 30 d post insemination. Data were analyzed using a MIXED procedure of SAS and examined for effects of inseminator, body condition score (BCS), and location and age. Statistical significance was determined at P &lt; 0.05 and a tendency at 0.05&lt; P &lt; 0.10. Age, BCS, and location did not affect (P &gt; 0.05) pregnancy rates. Cows exposed to the pre-synchronization program tended to have greater AI pregnancy rates compared to cows that did not receive the pre-synchronization program (57.7±5.3 vs. 46.9±5.3%, respectively; P = 0.0687). AI pregnancy rates were greater in cows with &gt;1 ng/mL P4 compared to cows with &lt; 1 ng/mL P4 at the start of FTAI (77.7±7 vs. 55.7±6.2%, respectively; P = 0.0204). Furthermore, AI pregnancy rates were decreased by inseminator C (26.1±7.4) compared to the other inseminators this breeding season (A-54.4±7.9; B- 62.3±5.3; D-57.8±7.2; and E -51.1±5.2; P = 0.0026). Based on these data, incorporating a pre-synchronization program to ensure the presence of a CL at the start of a FTAI protocol may improve pregnancy success in postpartum beef cows.

scholarly journals Comparison of reproductive performance of AI- and natural service-sired beef females under commercial management

2021 ◽  
Author(s):  
M A Marrella ◽  
R R White ◽  
N W Dias ◽  
C Timlin ◽  
S Pancini ◽  
...  
Keyword(s):  
Body Condition ◽  
Reproductive Performance ◽  
Mixed Models ◽  
Body Condition Score ◽  
Calving Interval ◽  
Estrus Synchronization ◽  
Age At First Calving ◽  
Condition Score ◽  
Pregnancy Status ◽  
Natural Service

Abstract The objective of this study was to assess differences in reproductive performance of natural service and artificial insemination (AI) sired beef females based on pregnancy outcomes, age at first calving, and calving interval. Data were sourced from 8,938 cows sired by AI bulls and 3,320 cows sired by natural service bulls between 2010 and 2017. All cows were in a commercial Angus herd with 17 management units located throughout Virginia and represented spring and fall calving seasons. All calves were born to dams managed with estrus synchronization. Pregnancy was analyzed with generalized linear mixed models and other reproductive measures with linear mixed models in R. Six models were evaluated with the dependent variables of pregnancy status at the first diagnosis, pregnancy status at the second diagnosis, pregnancy type (AI or natural service) at the first diagnosis, pregnancy type at the second diagnosis, calving interval, and age at first calving. Independent variables differed by model but included sire type of the female (AI or natural service), pre-breeding measures of age, weight, and body condition score, postpartum interval, sex of the calf nursing the cow, and management group. No differences were observed between AI- and natural service-sired females based on pregnancy status at first and second pregnancy diagnosis (P &gt; 0.05). Sire type was only found to be significant for age at first calving (P &lt; 0.05) with AI-sired females being 26.6 ± 1.6 days older at their first calving, which was expected because AI-sired females were born early in the calving season making them older at breeding. Surprisingly, age and body condition score were not significant predictors of pregnancy (P &gt; 0.05). Body weight at breeding was not significant for pregnancy (P &gt; 0.05) but was significant for age at first calving (P &lt; 0.05). These data suggested that lighter heifers calved earlier which contradicts our original hypothesis. Overall, commercial Angus females sired by AI or natural service bulls had similar reproductive performance. Factors that were commonly associated with reproductive success were not significant in this commercial Angus herd managed with estrus synchronization. Given the size of these data, the importance of body condition, age, and weight should be reassessed in modern genetics and management practices.

10 Effect of 1 or 2 doses of prostaglandin in a resynchronization protocol for timed artificial insemination in beef cows

2019 ◽  
Vol 31 (1) ◽  
pp. 131
Author(s):  
G. A. Pessoa ◽  
A. P. Martini ◽  
A. P. Baioco ◽  
E. F. Machado Filho ◽  
H. F. Pinto ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Device Removal ◽  
Pregnancy Diagnosis ◽  
Oestradiol Benzoate ◽  
Device Use

The objective of this study was to compare the effects of 1 and 2 prostaglandin doses in a timed AI (TAI) resynchronization protocol on the pregnancy rate. This study was performed during the 2017-2018 breeding season on 10 commercial farms located in the central and southwest region of Rio Grande do Sul, Brazil. A total of 2347Bos taurus beef cows (Angus, Hereford) with a body condition score 2.90±0.15 (1=thin, 5=obese) and 40±5.1 days postpartum were used. In the beginning of first synchronization TAI protocol, on Day −11, the animals received 2mg of oestradiol benzoate IM (Gonadiol®, Zoetis Saúde Animal, São Paulo, SP, Brazil) and a progesterone (P4) intravaginal device (CIDR®, Zoetis). On Day −4, the cows received 12.5mg of dinoprost tromethamine IM (PGF, Lutalyse®, Zoetis). On Day −2, the animals received 1.0mg of oestradiol cypionate IM (ECP®, Zoetis) associated with the treatment with 300IU of eCG IM (Novormon®, Zoetis) and the P4 device was removed. The TAI was done on Day 0 (48 h after P4 device removal). The resynchronization protocol was started on Day 23 without pregnancy or oestrus detection; all cows were randomly assigned to receive a new, once-used, or twice-used P4 device (CIDR®) and given 2mg of oestradiol benzoate. On Day 30, pregnancy diagnosis was performed with transrectal ultrasonography. Pregnant cows (n=1021) had the P4 device withdrawn and received no further treatment. Nonpregnant cows (n=1326) were randomly assigned into 2 groups. The 1PGF group (n=674) received a single dose of PGF on Day 30, and the 2PGF group (n=652) received PGF on Days 30 and 32. On Day 32, all cows received eCG and ECP, and the P4 device was removed. In both groups the TAI was performed 48h after the P4 device removal (Day 34). Pregnancy diagnosis was performed by ultrasound 30 days after TAI (Day 64 of the breeding season). Data were analysed using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC, USA). The pregnancy rate obtained in the first synchronization protocol was 43.5% (1021/2347). The pregnancy rate in the resynchronization protocol was similar (P=0.49) between PGF doses [1PGF=39.5% (266/674); 2PGF=40.6% (265/652). No interactions were observed between P4 device use and PGF dose (P=0.38). The pregnancy rates were similar when comparing 1PGF and 2PGF using a new P4 device [1PGF=43.2% (35/81); 2PGF=56% (93/166); P=0.67], once-used P4 device [1PGF=39% (163/418); 2PGF=40.6% (140/345); P=0.64], or twice-used P4 device [1PGF=38.9% (68/175); 2PGF=22.7% (32/141); P=0.14]. In conclusion, a second dose of prostaglandin in the resynchronization protocol was not necessary to achieve high resynchronization pregnancy rates with TAI in Bos taurus beef cows.

7 Pregnancy rates in suckled beef cows synchronized with a shortened progesterone/oestradiol-based protocol (J-synch) and inseminated with conventional or sexed-sorted semen

2019 ◽  
Vol 31 (1) ◽  
pp. 129 ◽  
Author(s):  
G. A. Bo ◽  
E. E. Huguenine ◽  
J. J. de la Mata ◽  
R. L. R. de Carneiro ◽  
A. Menchaca
Keyword(s):  
Corpus Luteum ◽  
Linear Model ◽  
Body Condition ◽  
Binary Data ◽  
Body Condition Score ◽  
General Linear Model ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Oestradiol Benzoate ◽  
Condition Score

An experiment was designed to evaluate pregnancy rates (P/AI) in suckled beef cows synchronized with a progesterone (P4)/oestradiol-based protocol (J-Synch) and inseminated (AI) with sexed or nonsexed (conventional) semen. Angus or Angus crossbred cows (n=877), 60 to 90 days postpartum, with a body condition score of 2.5 to 3.5 (scale of 1 to 5) and a corpus luteum or a follicle &gt;8mm in diameter detected by ultrasonography, were randomly allocated to be AI with sexed-sorted or nonsexed (conventional) semen. The experiment was performed in 4 farms, and the sexed-sorted (SexedUltra™ 4M, with 4 million sperm; ST Genetics, Navasota, TX, USA) and conventional (25 million sperm) semen were from split ejaculates from 5 Angus bulls. All cows received a P4 device (DIB 0.5, Zoetis, Villa Adelina, Argentina) and 2mg of oestradiol benzoate (Gonadiol, Zoetis) on Day 0. On Day 6, cows received 400IU of eCG (Novormon 5000, Zoetis) and 500µg of cloprostenol (Ciclase DL, Zoetis) and DIB was removed. All cows were also tail painted and observed for signs of oestrus (i.e. &gt;30% of the tail paint rubbed off) at 60, 72, and 84h after DIB removal. Cows with the tail paint rubbed off by 60 or 72h after DIB removal were artificially inseminated at 72h with either sexed or conventional semen. Those not showing oestrus by 72h received 100µg of gonadorelin acetate (Gonasyn GDR, Zoetis) at that time and were artificially inseminated with either sexed-sorted or conventional semen 12h later (i.e. 84h). Pregnancy was diagnosed by ultrasonography 30 days after AI. Data were analysed by general linear model for binary data with a logit link. Overall, 76.4% (678/877) of cows showed oestrus 60 to 84h after DIB removal, and there were differences in P/AI between sexed-sorted and conventional semen (P&lt;0.01; Table 1); however, there was no farm effect (range: 52-59%) and no interactions. Fertility differed (P&lt;0.05) among bulls and ranged from 25.8 to 55.3% for sexed-sorted semen and from 53.1 to 73.9% for conventional semen. In cows artificially inseminated with sexed-sorted semen, P/AI was the highest in cows showing oestrus and AI at 84 h; however, no differences were detected among cows artificially inseminated with conventional semen (Table 1). Although P/AI was lower for sexed-sorted than conventional semen, tail painting for oestrus detection can be successfully applied to AI beef cows with sexed-sorted semen synchronized with a shortened P4/oestradiol-based protocol. Table 1.Effect of semen type (sexed-sorted or conventional) and time of oestrus and AI on P/AI in suckled beef cows synchronized with a shortened P4/oestradiol-based protocol Research was supported by Fondo Nacional de Ciencia y Tecnología (FONCYT PICT 2017-4550) and UNVM.

scholarly journals Evaluation of the 7 & 7 Synch and 7-day CO-Synch + CIDR ® protocols for estrus synchronization of beef cows prior to fixed-time artificial insemination with conventional or sex-sorted semen

2020 ◽  
Author(s):  
C.M. Andersen ◽  
R.C. Bonacker ◽  
E.G. Smith ◽  
C.M. Spinka ◽  
S.E. Poock ◽  
...  
Keyword(s):  
Artificial Insemination ◽  
Bos Taurus ◽  
Body Condition Score ◽  
Fixed Time ◽  
Beef Cows ◽  
Pregnancy Rates ◽  
Sexed Semen ◽  
Condition Score ◽  
Prostaglandin F ◽  
Activation Status

AbstractAn experiment was designed to compare the recently developed 7 & 7 Synch and the 7-day CO-Synch + CIDR protocols for synchronization of estrus among beef cows prior to fixed-time artificial insemination (FTAI) with conventional or sex-sorted semen. Bos taurus cows (n = 1538) were blocked based on age and days postpartum (DPP) and randomly assigned to protocol and semen type. Cows treated with the 7-day CO-Synch + CIDR protocol (n = 769) received administration of gonadotropin-releasing hormone (GnRH; 100 μg gonadorelin) and insertion of a 1.38 g intravaginal progesterone releasing insert (CIDR) on Day -10, and administration of prostaglandin F2α (PG; 500 μg cloprostenol) coincident with CIDR removal on Day -3. Cows treated with 7 & 7 Synch (n = 769) received PG and insertion of CIDR on Day -17, GnRH on Day -10, and PG coincident with CIDR removal on Day -3. Estrus detection aids (Estrotect™) were applied to all cows on Day -3, and activation status was recorded at FTAI. Cows received FTAI 66 h after CIDR removal with either conventional (20 × 106 cells per unit) or sex-sorted (4 × 106 cells per unit; SexedULTRA 4M™) semen. A greater proportion of cows expressed estrus (P = 0.01) prior to FTAI following 7 & 7 Synch (82%; 629/769) compared with the 7-day CO-Synch + CIDR (64%; 492/769). Estrus expression was also affected by protocol × DPP (P = 0.0004), with 7 & 7 Synch resulting in a greater increase in the proportion of cows expressing estrus prior to FTAI among cows with greater DPP. Across protocols, body condition score (BCS) affected (P = 0.05) estrus expression, with greater proportion of cows expressing estrus prior to FTAI at greater BCS. Sex-sorted semen resulted in reduced (P < 0.0001) pregnancy rates to FTAI. Irrespective of semen type, greater (P = 0.001) pregnancy rates to FTAI were obtained among cows treated with 7 & 7 Synch (conventional semen: 72% [280/389]; sex-sorted semen: 52% [199/380]) compared with the 7-day CO-Synch + CIDR (conventional semen: 60% [231/383]; sex-sorted semen: 44% [171/386]). In summary, 7 & 7 Synch resulted in an increased proportion of cows expressing estrus prior to FTAI and an increased pregnancy rate to FTAI with conventional and sexed semen. With these results and ease of application, 7 & 7 Synch offers potential as a platform to improve success with fixed-time AI in beef cows.

Sign in / Sign up

Export Citation Format

Share Document