Response in female fertility and calf growth to selection for pregnancy rate in tropical beef cattle

1993 ◽  
Vol 44 (7) ◽  
pp. 1509 ◽  
Author(s):  
GP Davis ◽  
NJ Corbet ◽  
MJ Mackinnon ◽  
DJS Hetzel ◽  
KW Entwistle ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
First Generation ◽  
Bos Indicus ◽  
Pregnancy Rates ◽  
Breeding Value ◽  
Calf Growth ◽  
Lactating Cows ◽  
High Line ◽  
Calf Survival ◽  
Selection Of

Direct response to divergent selection based on estimated breeding value for female pregnancy rate in a herd of Bos indicus cross cattle was evaluated along with correlated responses in calf survival, weaning rate, cow liveweight and calf growth. Pregnancy rates were significantly higher ( P < 0.05) in heifers of the High line compared with the Low line (High-Low=15� 5%) and in lactating 4-year-old cows (25�9.5%) and in 3 of the 5 years of the study (average difference 24%). The Low line had significantly ( P < 0.05) higher pregnancy rates in 1 year (-16�5.4%). These differences in pregnancy rates were reflected in weaning rates, but calf survival was only different between the lines in 2 of the 4 years analysed (-6� 3.0% in 1990 and 18�6.5% in 1991). The High line had a significantly ( P < 0.05) shorter days to calving than the Low line in heifers (High=309�2.2 days v. Low= 315�2.5 days), lactating 3-year-old cows (3l5� 3.6 days v. 331�4.1 days), non-lactating 3-year-old cows (301�5.4 days v. 320�4.6 days) and lactating 4-year-old cows (311�3.9 days v. 336�4.9 days). Differences between the lines in pre-weaning growth varied according to generation with significantly lower (P < 0.05) weaning weights (182�3.1 kg v. 189�3.3 kg) and pre-weaning growth (790�17 g/day v. 826� 17 g/day) in first generation High line calves from foundation dams and no difference between the lines in second generation calves from first generation dams. Post-weaning growth was significantly higher ( P < 0.05) in High line calves (350� 5 g/day v. 327�5 g/day). The results indicate that selection of sires on EBV for pregnancy rate leads to improved fertility in heifers and 4-year-old lactating cows without adverse effects on progeny growth.

Effect of cattle tick (Boophilus microplus) infestation on performance of Bos indicus cross cows and their progeny

1988 ◽  
Vol 28 (1) ◽  
pp. 1 ◽  
Author(s):  
RG Holroyd ◽  
PJ Dunster ◽  
PK O'Rourke
Keyword(s):  
Pregnancy Rate ◽  
Bos Indicus ◽  
Treated Group ◽  
Pregnancy Rates ◽  
Boophilus Microplus ◽  
Cattle Tick ◽  
First Year ◽  
The Third ◽  
Lactating Cows ◽  
Tick Counts

The effects of cattle tick infestations on liveweight and fertility of Droughtmaster (1/2 Bos indicus) cows and on calf weaning weights were determined over 3 years. Tick populations on the control (non-dipped) group of cattle fluctuated, with mean annual tick counts/side being 9.5, 8.9 and 13.6 for years 1, 2 and 3 respectively, while the treated group of cattle, which were dipped every 21 days, were free of ticks. Tick counts were not related to fertility or liveweight change in pregnant-lactating cows or to calf growtb or weaning weights. Treatment for ticks significantly (P<0.05) affected liveweight change in pregnant-lactating cows on only a few occasions, and annual liveweight changes were not significantly influenced by treatment. When lactating cow pregnancy rates were low (< 30% for control cows), treatment for ticks increased the pregnancy rate by about 100% in 2 of the 3 years, these differences being significant only in the last year. Calves in the treated group were born significantly earlier in the first year and had significantly lighter birth weights in the third year. Treated calves grew faster to weaning and had higher weaning weights (mean difference 17.9 kg) than control calves but differences were significant in the first and third years only.

241 EFFECT OF PRODUCTION EFFICIENCY IN THE LIKELIHOOD OF PREGNANCY OF IN VITRO-DERIVED BOVINE EMBRYOS

2015 ◽  
Vol 27 (1) ◽  
pp. 210
Author(s):  
L. F. Feres ◽  
L. S. A. Camargo ◽  
M. P. Palhao ◽  
F. Z. Brandao ◽  
J. H. M. Viana
Keyword(s):  
Pregnancy Rate ◽  
Production Efficiency ◽  
Production Systems ◽  
Bos Indicus ◽  
Pregnancy Rates ◽  
In Vitro Production ◽  
Cleavage Rate ◽  
Embryo Production ◽  
Chi Square

Improving in vitro culture systems to optimize embryo yield has been a major research goal. The relationship between the efficiency of embryo production systems and the pregnancy outcomes, however, remain controversial. The aim of the present study was to evaluate the likelihood of pregnancy of in vitro-produced embryos derived from batches with different relative efficiency indexes. Data of 702 ovum pick-up (OPU) and in vitro embryo production (IVEP) sessions, and of 2456 embryo transfers, recorded from 2008 to 2012, were evaluated. All donors were from the same herd, and were of the same breed (Gir, Bos indicus), as well as the semen used for IVF. The cumulus-oocycte complex (COC) recovery and IVEP were performed by the same team, in a single IVF laboratory, and using standard medium and procedures. Only data from embryos transferred as fresh were used, and records from 97 OPU/IVEP sessions in which no embryo was produced, or embryos were frozen or discharged due to lack of recipients, were discharged. The remaining 605 sessions were stratified in quartiles (I to IV, each one corresponding to 25% of total data) according to COC production of the donors, or stratified in ranges (0–25%, 26–50%, 51–75%, and 76–100%) according to COC quality (percentage of viable COC or of grade I COC) and to embryo production efficiency endpoints (cleavage rate, blastocyst rate). Pregnancy rates were compared among quartiles or ranges by the chi-square method. On average, the Gir donors produced 24.8 ± 0.6 COC per OPU, from which 14.4 ± 0.4 were classified as viable (57.8%), and 3.2 ± 0.1 as grade I (12.9%). On average 6.1 ± 0.2 embryos (morulas and blastocysts) were produced per OPU per donor, and mean pregnancy rate was 30.9%. As expected, donors with greater total COC yield (quartile I) also produced more viable oocytes (25.5 ± 0.7 v. 15.7 ± 0.3, 10.5 ± 0.2 and 5.8 ± 0.2), more COC grade I (4.8 ± 0.4 v. 3.9 ± 0.3, 2.6 ± 0.2 and 1.6 ± 0.1), and more embryos (9.0 ± 0.4 v. 6.9 ± 0.3, 5.0 ± 0.2 and 3.3 ± 0.1) than donors from quartiles II, III, or IV, respectively (P < 0.0001). Nevertheless, there was no difference (P > 0.05) in pregnancy rates for embryos produced from donors ranked in the different quartiles (30.9 v. 29.3, 31.5, and 30.5% for quartiles I to IV, respectively). Similarly, there was no difference (P > 0.05) in the pregnancy rate of embryos derived from OPU sessions in which there was a high or low percentage of viable or grade I COC. In vitro production efficiency (cleavage and blastocyst rates) also had no effect (P > 0.05) on further pregnancy rates. In conclusion, these results suggest that there is no relationship among the average number or quality of the COC recovered by OPU, the efficiency of IVEP, and the likelihood of pregnancy of in vitro-derived embryos.Research was supported by Fazendas do Basa, CNPq, and Fapemig.

11 Invivo-derived embryo pregnancy rates at Maddox Dairy from 2008 to 2018

2020 ◽  
Vol 32 (2) ◽  
pp. 130
Author(s):  
D. Demetrio ◽  
A. Magalhaes ◽  
M. Oliveira ◽  
R. Santos ◽  
R. Chebel
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Milk Production ◽  
Pregnancy Rates ◽  
The Other ◽  
Lactating Cows ◽  
June July August ◽  
June July ◽  
Management Changes ◽  
July August September

Maddox Dairy, located in Riverdale, CA, USA, is a Holstein herd that milks 3500 cows with a 305-day mature-equivalent milk production of 12 800 kg, and they have been producing high genetic animals by embryo transfer (ET) since the early 1980s. Invivo-derived embryos from Holstein donors were transferred fresh (grade 1 or 2) or frozen (grade 1), at morula (4), early blastocyst (5), or blastocyst (6) stage, to virgin heifers (VH, natural oestrus, 13-15 months old) or lactating cows (LC, Presynch-Ovsynch, 86 days in milk, first or second lactation) 6 to 9 days after oestrus. Pregnancy diagnosis was done by transrectal ultrasonography at 32-46 days in VH and by the IDEXX PAG test at 30 days in LC. June, July, August, September, and October were called critical months (first service AI conception rate drops below 44%) and compared with the other months. The data from 32 503 ETs between January 2008 and December 2018 are summarised on Table 1. Pregnancy rates (PR) are lower for LC recipients than for VH. Embryo transfers performed 7 or 8 days after oestrus had higher PR in both types of recipients and embryos, but Day 6 and 9 oestrus are also used with fair results. The season does not seem to affect PR. There is not enough difference in the combination of stage and days from oestrus for invivo-derived embryos. These numbers do not belong to a planned experiment. Several management changes during the years were made, which make it very difficult to apply statistical methods to analyse the data correctly. They are used as a tool to make decisions in an attempt to improve future results. Table 1.Pregnancy rate (PR) of virgin heifers (top) and lactating cows (bottom)-fresh (SH) and frozen (OZ) invivo-derived embryo transfer1 Heat-months SH-ST4 SH-ST5 SH-ST6 SH-All OZ-ST4 OZ-ST5 OZ-ST6 OZ-All PR% n PR% n PR% n PR% n PR% n PR% n PR% n PR% n Heifers 6 d-CM 62 934 66 243 68 69 63 1246 56 473 58 219 62 42 57 734 6 d-OM 62 1623 67 489 69 211 64 2323 56 600 55 296 48 137 55 1033 6 d-T 62 2557 67 732 69 280 63 3569 56 1073 57 515 51 179 56 1767 7 d-CM 64 1506 68 495 67 221 65 2222 60 822 62 340 63 156 61 1318 7 d-OM 66 2723 68 1021 69 510 67 4254 57 1120 59 581 57 231 58 1932 7 d-T 66 4229 68 1516 69 731 67 6476 58 1942 60 921 60 387 59 3250 8 d-CM 65 1348 64 518 67 322 65 2188 59 595 64 258 63 108 61 961 8 d-OM 66 2166 68 886 70 510 67 3562 61 770 60 364 51 130 60 1264 8 d-T 66 3514 67 1404 69 832 66 5750 60 1365 62 622 56 238 60 2225 9 d-CM 60 109 56 43 70 20 60 172 60 5 33 6 50 4 47 15 9 d-OM 58 129 63 57 60 40 60 226 63 16 50 18 75 4 58 38 9 d-T 59 238 60 100 63 60 60 398 62 21 46 24 63 8 55 53 All-CM 64 3897 66 1299 67 632 65 5828 58 1895 61 823 63 310 60 3028 All-OM 65 6641 67 2453 69 1271 66 10 365 58 2506 58 1259 53 502 58 4267 All-T 65 10 538 67 3752 69 1903 66 16 193 58 4401 60 2082 57 812 59 7295 Lactating cows 6 d-CM 54 265 48 86 50 12 53 363 38 141 31 77 50 10 36 228 6 d-OM 49 463 52 203 45 56 50 723 46 101 48 54 59 27 48 182 6 d-T 51 728 51 289 46 68 51 1086 41 242 38 131 57 37 42 410 7 d-CM 54 755 59 274 56 103 55 1137 43 928 48 450 43 192 45 1570 7 d-OM 55 914 66 367 54 109 58 1393 46 1052 45 564 47 353 46 1969 7 d-T 55 1669 63 641 55 212 57 2530 45 1980 46 1014 46 545 45 3539 8 d-CM 63 252 68 82 76 33 65 368 48 219 56 80 42 33 50 332 8 d-OM 61 257 64 161 53 47 61 466 50 191 53 77 56 16 51 284 8 d-T 62 509 65 243 63 80 63 834 49 410 55 157 47 49 50 616 All-CM 56 1272 58 442 60 148 57 1868 44 1288 47 607 43 235 45 2130 All-OM 55 1634 62 731 51 212 56 2582 47 1344 46 695 48 396 47 2435 All-T 55 2906 60 1173 55 360 57 4450 45 2632 47 1302 46 631 46 4565 1ST=stage; CM=critical months (June, July, August, September, and October); OM=other months.

scholarly journals Productive and reproductive performances and expected response to selection of second generation of quail varieties conserved at Bangladesh Livestock Research Institute

2017 ◽  
Vol 2 (4) ◽  
pp. 631-634
Author(s):  
Shakila Faruque ◽  
Md Yousuf Ali ◽  
AKH Fazlul Haque Bhuyian ◽  
Ziaul Faruque Joy ◽  
Md Ataul Goni Rabbani
Keyword(s):  
Body Weight ◽  
First Generation ◽  
Second Generation ◽  
Breeding Value ◽  
Response To Selection ◽  
White Variety ◽  
Black And White ◽  
Heritable Trait ◽  
Selection Of ◽  
Research Institute

Individual selection is particularly indispensable in selection experiments for body weight in quail. Body weight is highly heritable trait. The study was conducted with the objective to assess the productive and reproductive performance and expected response to selection of second generation (G2) of four quail varieties conserved at Bangladesh livestock Research Institute. At 5th week of age, quails of first generation (G1) were selected on the basis of breeding value according to their 5th week body weight. A total of 1953-day-old chicks were hatched in two batches for producing second generation (G2). Diet containing 24% crude protein and 3000 kcal ME/kg were provided to the birds. The data were analyzed in a CRD factorial arrangement by General Linear Model (GLM) Univariate Procedure in SPSS Computer Program. The highest fertility was observed in White (98.31%) variety and hatchability was in Japanese (97.75%) variety. Differences in chick weight at hatch between White and Brown, Brown and Japanese, Japanese and Black, Black and White were approximately 6.90%, 2.74%, 6.20% and 10.51% respectively. The effect of variety and batch on 5th week body weight was significant (p<0.001) but interaction effect of variety and batch was not significant (p>0.05). Black quail had significantly (?2 = 25.00; p<0.01) higher (17.62%) chick mortality than that of other three varieties. As a result of selection, body weight at 5th weeks of age was expected to improve by 4.34g vs. 6.51g; 1.21g vs. 4.33g, 1.68g vs. 3.77g and 1.02g vs. 2.40g respectively for Japanese, White, Brown and Black males and females quail genotypes. It is therefore can be concluded that the White variety is superior in terms of higher body weight and higher fertility and medium chick mortality among the four quail varieties. In each generation, slight response was obtained for selection.Asian J. Med. Biol. Res. December 2016, 2(4): 631-634

Prepartum supplementation effects on growth and fertility in Bos indicus-cross cows

1997 ◽  
Vol 37 (2) ◽  
pp. 141 ◽  
Author(s):  
G. Fordyce ◽  
L. A. Fitzpatrick ◽  
T. J. Mullins ◽  
N. J. Cooper ◽  
D. J. Reid ◽  
...  
Keyword(s):  
Body Condition ◽  
Post Partum ◽  
Bos Indicus ◽  
Late Pregnancy ◽  
Dry Season ◽  
Pregnancy Rates ◽  
Wet Season ◽  
Calf Growth ◽  
Treatment Groups ◽  
Calving Season

Summary. Three experiments were conducted in the dry tropics of north Australia using Bos indicus-cross cows. Cows in mid–late pregnancy were either unsupplemented during the late dry season or offered ad libitum (2 kg/day) molasses with 7.4% urea (w/w) (M8U) or cottonseed meal (1 kg/day) for up to 54 days commencing 2 months before the start of the calving season. Supplementation reduced weight loss in experiments 1 and 2 (P<0.05), but had no significant effect on weight or body condition in experiment 3. Supplementation had no effect on subsequent calf growth or cow lactation yields. Following early wet season rains in experiment 1, 9 and 49% of cows were ovulating 40 and 80 days post-partum, respectively, with no effect of supplementation. In experiment 2, 10 and 100% of cows had ovulated by 60 and 200 days post-partum, respectively. At any time between 80 and 180 days post-partum, supplemented cows were more likely to be cycling (P<0.05), independent of supplementation effects on weight or body condition. The average post-partum interval to oestrus was 30 days less in cows supplemented for 42 days (P = 0.08). In experiment 3, pregnancy rates in 1/2 and 3/4 Brahmans supplemented with M8U for 54 days (MU54) or whose calves were weaned at 2–3 months of age (WEAN) were 14% higher in the latter 2 months of mating than in cows supplemented for less than 40 days. Good seasonal conditions resulted in high pregnancy rates in all mature 5/8 Brahmans; when not weaned early, their average calving to conception interval (CCI) was 54 days (s.e. = 8.5 days). Pregnancy rates of first-lactation 5/8 Brahmans (average CCI of 125 days) supplemented for 39 days or less and weaned when calves averaged 6 months of age were 14–32% lower between 2 and 9 months post-partum than in contemporaries in the MU54 or WEAN treatment groups. It was concluded that dry-season supplementation of mid- to late-pregnant Bos indicus-cross cows with an energy concentrate for 42–54 days (‘spike’ feeding) may reduce post-partum anoestrus intervals via a mechanism which is not dependent on the effects on weight or body condition.

Productivity of Hereford, highgrade Simmental and Belmont Red beef herds in central Queensland. 3. Explanatory models for pregnancy rate

1992 ◽  
Vol 32 (5) ◽  
pp. 563 ◽  
Author(s):  
PK O'Rourke ◽  
CR Esdale ◽  
CJ Howitt ◽  
TH Rudder
Keyword(s):  
Pregnancy Rate ◽  
Explanatory Models ◽  
Pregnancy Rates ◽  
Low Fertility ◽  
High Fertility ◽  
Lactating Cows ◽  
Highly Sensitive ◽  
Breeding Herd ◽  
Beef Herds ◽  
Plateau Level

Statistical models for pregnancy rate of Hereford, highgrade Simmental and Belmont Red cows were developed for brigalow pastures in central Queensland. Cows grazing improved pasture at 1 breeder/2 ha over 6 years, from 1979 to 1985, were mated to single sires for 78 days from early December each year and their calves weaned in May. Overall herd pregnancy rates were 74% Hereford, 69% highgrade Simmental and 86% Belmont Red. The 2-year-old maidens and non-lactating cows had higher rates than lactating cows for Hereford and highgrade Simmental. Mature, lactating and non-lactating cows had higher liveweights at the start of mating than first lactation cows and all were heavier than maidens. Pregnancy rate for maidens was not affected by liveweight, but 71% Hereford, 90% highgrade Simmental and 95% Belmont Red were above 300 kg at the start of mating. Response in pregnancy rate to liveweight at start of mating plateaued above 375 kg for first lactation Belmont Red and mature lactating Hereford; above 400 kg for mature lactating Belmont Red; and above 425 kg for mature lactating highgrade Simmental; but this liveweight was not important for first lactation Hereford and highgrade Simmental, nor for non-lactating cows. Mature cows calving in the first 6 weeks of the season had 13-30% higher pregnancy rates than those calving later. Previous lactation status did not affect pregnancy rate for highgrade Simmental and Belmont Red, but Hereford cows rearing a calf in the previous year had 14% higher pregnancy rates than those failing to rear a calf. Breed differences were apparent in the responses to the factors modelled. Pregnancy rates of lactating Belmont Red cows were sensitive to time of calving and liveweight at start of mating, even though these rates exceeded 80%. Mature, lactating highgrade Simmental were highly sensitive and Hereford intermediate, but first lactation and non-lactating Hereford and highgrade Simmental did not respond to these factors, even though pregnancy rates were low. Segregation of the breeding herd into high, intermediate and low expected fertility groups can be based on calving time and liveweight at start of mating. The high fertility group, consisting of cows calving in the first 6 weeks of the season and weighing greater than the plateau level, had advantages compared with the herd averages of 16 and 8% in fertility for first and mature lactating Belmont Red, respectively. Conversely, the low fertility group, consisting of late calving cows of low liveweight, had disadvantages of 30 and 18% for first and mature lactating Belmont Red. respectively.

scholarly journals Evaluation of pregnancy rates of Bos indicus cows subjected to different synchronization ovulation protocols using injectable progesterone or an intravaginal device

2016 ◽  
Vol 37 (6) ◽  
pp. 4149
Author(s):  
Jefferson Tadeu Campos ◽  
Fábio Morotti ◽  
Camila Bortoliero Costa ◽  
Larissa Zamparone Bergamo ◽  
Marcelo Marcondes Seneda
Keyword(s):  
Pregnancy Rate ◽  
Bos Indicus ◽  
Fixed Time ◽  
Pregnancy Rates ◽  
Estrus Cycle ◽  
Device Removal ◽  
Alternative Source ◽  
Group Iii ◽  
Group I ◽  
Intravaginal Device

This study evaluated the pregnancy rate in Nelore cows (Bos indicus) that were subjected to fixed-time artificial insemination (FTAI) using different protocols consisting of injectable progesterone (P4) or an intravaginal device (impregnated with P4). Multiparous cows 72-84 months in age, 30-45 days postpartum, were selected on the basis of the absence of a corpus luteum (CL) and follicles < 8 mm after transrectal palpation and ultrasound examinations. On a random day of the estrus cycle (D0), the selected animals (n = 135) were randomly assigned to one of three experimental groups (n = 45 each). Group I (injectable P4/FTAI 36 hours) received 250 mg of injectable P4 and 2 mg EB on D0; on D7, they received 500 µg of cloprostenol; on D8, 300 IU of eCG and 1 mg of EB were administered; and finally, FTAI was performed 36 hours after the application of EB. Group II (injectable P4/FTAI 48 hours) received the same protocol as Group I, except that the FTAI was performed 48 hours after ovulation induction. The animals of Group III (Control/CIDR) received a conventional protocol for FTAI using an intravaginal device (D0: P4 and 2 mg EB; D8: device removal, 500 µg cloprostenol, 300 IU eCG, 1 mg EB; and FTAI performed 48 hours after removal of the device). The results showed that cows synchronized with the conventional protocol for FTAI (Control/CIDR) had a higher pregnancy rate (60 %, 27/45) than those synchronized with an injectable P4/FTAI 36 hours (33.33 %; 15/45, P = 0.010). However, the group receiving injectable P4 group/FTAI 48 hours had a similar pregnancy rate (48.9 %; 22/45; P = 0.290) when compared to both the group receiving the conventional protocol and that receiving injectable P4/FTAI 36 hours (P = 0.134). Although the injectable P4 may affect pregnancy rate with the FTAI performed in 36 hours, we found similar pregnancy rates from cows inseminated 48 hours after induction ovulation, considering injectable or intravaginal P4. Therefore, we suggest that injectable P4 represents an alternative source of progesterone for synchronization of cattle for FTAI.

scholarly journals Influence of Injectable Progesterone on the Pregnancy Rate of Heifers Receiving Bovine Embryos

2020 ◽  
Vol 48 ◽  
Author(s):  
Caio Cezar Da Silva ◽  
Hélton Aparecido Garcia Gregianini ◽  
Jennifer Teodoro Ferreira Gregianini ◽  
José Antônio Dell’Aqua Junior ◽  
Jefferson Viana Alves Diniz ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Physiological State ◽  
Bos Indicus ◽  
Fixed Time ◽  
Treated Group ◽  
Pregnancy Rates ◽  
Control Group ◽  
Bovine Embryos

Background: In vitro embryo production (IVEP) allows the spread of superior animal genetics, but pregnancy rates show a high variability with this biotechnique. In the initial stage of pregnancy, progesterone plays a fundamental role in uterine preparation, acting on embryonic growth, implantation, and development. However, on the day of the IVEP transfer to the recipients, progesterone levels may be lower than that expected, influencing the uterine environment and, consequently, the pregnancy rate. Therefore, the objective of this study was to evaluate the pregnancy rate in heifers after the administration of injectable progesterone (P4) in the fixed-time embryo transfer (FTET) protocol.Materials, Methods & Results: The experiment was conducted inside a rural property near the city of Rio Branco, Acre, Brazil. The experimental group consisted of 232 animals, including 78 zebuine (Bos indicus) and 154 mixed (½ blood B. indicus and ½ blood B. taurus) animals, aged between 16 and 24 months, with a mean weight of 300 and 330 kg for zebuine and mixed animals, respectively. The selected animals were previously synchronized using the progesterone-estrogen-prostaglandin-estrogen protocol. Embryo transfer was performed on day 18 of the protocol, which was 9 days after the removal of intravaginal progesterone implant. On day 15 of the protocol, that is, 144 h (6 days) after the device removal, the animals were randomly distributed into two experimental groups: Control Group (CG; 0.5 mL of 0.9% saline solution, intramuscular) and Treated Group (P4G; 0.5 mL of injectable P4, 150 mg, intramuscular). Chi-square test was used for the statistical analysis of the pregnancy rate at a 5% probability. After 23 days of embryo transfer, pregnancy was diagnosed by ultrasonography. The general pregnancy rate, considering all groups (CG and P4G) and breeds included, was 55.17% (128/232). The pregnancy rates of the P4G and CG groups, regardless of breeds, were 55.08% (65/118) and 55.26% (63/114), respectively, with no statistical difference (P = 0.8344). Angus animals presented a similar pregnancy rate in the P4G and CG groups of 54.93% (39/71) and 57.83% (48/83), respectively. Furthermore, similar results were found for the Nellore breed, with no difference in pregnancy rate between the CG (55.81%, 24/43) and P4G (48.57%, 17/35) groups.Discussion: The strategy of using P4 to increase the pregnancy rate is very widespread in fixed-time artificial insemination (FTAI) protocols, although differences still exist. The literature presents zero or negative effects, as in this study, when exogenous P4 was used to increase endogenous P4 concentrations and, consequently, the pregnancy rate. However, some studies demonstrated the beneficial effects of increasing blood P4 concentrations, and that the increased fertility depends on the method and time of P4 supplementation and the animal’s physiological state. In this context, the fact that the injectable progesterone supplementation did not increase the pregnancy rate in this study is justified mainly by factors such as the animal category used (heifers), time of P4 supplementation (day 4 after ovulation), biotechnology used (FTET), and the heterogeneous characteristics related to phases of the estrous cycle of heifers. Supplementation with 150 mg of injectable long-acting progesterone intramuscularly did not interfere in the pregnancy rate of Angus and Nellore heifers receiving bovine embryos.

scholarly journals Embryo transfer as a tool for improving fertility of heat-stressed dairy cattle

2007 ◽  
Author(s):  
Peter J. Hansen ◽  
Amir Arav
Keyword(s):  
Elevated Temperature ◽  
Heat Shock ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Caspase 3 ◽  
Culture Conditions ◽  
Caspase Activity ◽  
Lactating Cows ◽  
Selection Of

The overall objective of the current proposal is to develop procedures to improve the pregnancy rate achieved following transfer of fresh or cryopreserved embryos produced in the laboratory into heat-stress recipients. The overall hypothesis is that pregnancy rate in heat-stressed lactating cows can be improved by use of embryo transfer and that additional gains in pregnancy rate can be achieved through development of procedures to cryopreserve embryos, select embryos most likely to establish and maintain pregnancy after transfer, and to enhance embryo competence for post-transfer survival through manipulation of culture conditions. The original specific objectives were to 1) optimize procedures for cryopreservation (Israel/US), 2) develop procedures for identifying embryos with the greatest potential for development and survival using the remote monitoring system called EmbryoGuard (Israel), 3) perform field trials to test the efficacy of cryopreservation and the EmbryoGuard selection system for improving pregnancy rates in heat-stressed, lactating cows (US/Israel), 4) test whether selection of fresh or frozen-thawed blastocysts based on measurement of group II caspase activity is an effective means of increasing survival after cryopreservation and post-transfer pregnancy rate (US), and 5) identify genes in blastocysts induced by insulin-like growth factor-1 (IGF-1) (US). In addition to these objectives, additional work was carried out to determine additional cellular determinants of embryonic resistance to heat shock. There were several major achievements. Results of one experiment indicated that survival of embryos to freezing could be improved by treating embryos with cytochalasin B to disrupt the cytoskeleton. An additional improvement in the efficacy of embryo transfer for achieving pregnancy in heat-stressed cows follows from the finding that IGF-1 can improve post-transfer survival of in vitro produced embryos in the summer but not winter. Expression of several genes in the blastocyst was regulated by IGF-1 including IGF binding protein-3, desmocollin II, Na/K ATPase, Bax, heat shock protein 70 and IGF-1 receptor. These genes are likely candidates 1) for developing assays for selection of embryos for transfer and 2) as marker genes for improving culture conditions for embryo production. The fact that IGF-1 improved survival of embryos in heat-stressed recipients only is consistent with the hypothesis that IGF-1 confers cellular thermotolerance to bovine embryos. Other experiments confirmed this action of IGF-1. One action of IGF-1, the ability to block heat-shock induced apoptosis, was shown to be mediated through activation of the phosphatidylinositol 3-kinase pathway. Other cellular determinants of resistance of embryos to elevated temperature were identified including redox status of the embryo and the ceramide signaling pathway. Developmental changes in embryonic apoptosis responses in response to heat shock were described and found to include alterations in the capacity of the embryo to undergo caspase-9 and caspase-3 activation as well as events downstream from caspase-3 activation. With the exception of IGF-1, other possible treatments to improve pregnancy rate to embryo transfer were not effective including selection of embryos for caspase activity, treatment of recipients with GnRH.and bilateral transfer of twin embryos. In conclusion, accomplishments achieved during the grant period have resulted in methods for improving post-transfer survival of in vitro produced embryos transferred into heat-stressed cows and have lead to additional avenues for research to increase embryo resistance to elevated temperature and improve survival to cryopreservation. In addition, embryo transfer of vitrified IVF embryos increased significantly the pregnancy rate in repeated breeder cows.

24 EVALUATION OF THE PREGNANCY RATE OF FIXED-TIME ARTIFICIALLY INSEMINATED BOS INDICUS COWS USING HETEROSPERMIC AND MONOSPERMIC SEMEN

2013 ◽  
Vol 25 (1) ◽  
pp. 159
Author(s):  
J. P. Detomini ◽  
R. R. Tirloni ◽  
C. V. Araujo ◽  
L. R. Martins
Keyword(s):  
Pregnancy Rate ◽  
Estrous Cycle ◽  
Body Condition Score ◽  
Bos Indicus ◽  
Fixed Time ◽  
Estradiol Benzoate ◽  
Pregnancy Rates ◽  
Chi Square ◽  
Mato Grosso ◽  
Chi Square Test

The aim of this study was to establish a comparison between heterospermic and monospermic semen on the pregnancy rate of fixed-time AI Bos indicus cows. The experiment was conducted in the state of Mato Grosso, Brazil, during December 2010 and February 2011. Multiparous (n = 173) and primiparous (n = 204) Nelore cows, 45 ± 15 days postpartum, were evaluated on body condition score (BCS; score 1 to 9), and those that presented BCS between 5 and 8 were selected. Two protocols of estrous cycle synchronization were performed (PeCG and Pshang). Synchronization of the estrous cycle was achieved with the aid of the following protocol: on Day 0, all animals were treated with a progesterone vaginal implant with 1.9 g of progesterone combined with an IM injection of 2 mg of estradiol benzoate. On Day 7, an IM injection of 12.5 mg of dinoprost was administered. On Day 9, implants were withdrawn and the animals received an IM injection of 0.5 mg of estradiol cypionate. On Day 9, part of the animals (n = 222) received an IM injection of 300 IU mg of eCG (PeCG) and the other part (n = 155) had their calves removed for 48 hours (Pshang). All animals were inseminated 46 to 52 h after the end of the protocol. Cows were allocated randomly in 4 groups according to the donor male sample in the semen straw and groups were designated as MA (monospermic straw from bull A; n = 110), MB (monospermic straw from bull B; n = 102), MC (monospermic straw from bull C; n = 108), and HT (heterospermic sample from bulls A, B, and C; n = 57). Commercially available semen straws from Aberdeen Angus donors were used (ABS Pecplan, Brazil). Pregnancy diagnosis was performed 35 days after AI using real-time ultrasonography. Results are summarized in Table 1. There was no statistical difference between MA, MB, MC, and HT in any group according to the chi-square test (P > 0.05). However, there was a remarkable difference in pregnancy rates among the 3 bulls tested considering both protocols, probably due to the variation in the ovulation moment. Table 1.Pregnancy rates of Nelore cows submitted to FTAI protocol inseminated with monospermic (bull A, B, or C) or heterospermic (HT) semen

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