Multiparous Bos Indicus Research Articles

Somatic Cell Count Evaluation in Early Lactation Betweenprimiparous and Multiparous Bos indicus Cows (SDG'S)

Objective: A study examined the relationship between somatic cell count (SCC) and milk yield Theoretical Framework: The sustainable development of dairy farms will be key to stopping the growing agricultural frontier. In comparison to breeds from temperate regions, tropical bovine production is low in terms of milk kilos, composition, or udder health. Method: We enrolled one hundred fifty cows (Primiparous, PM, 75 and Multiparous, MP 75) in early lactation (days in milk, PM =134 ± 3; MP = 136 ± 5), milk production (9,88 kg/d, on average) of the creole breed Gyr lechers. Prior to the assignment to each treatment, the SCC values were lower than 220,000 cells/mL, on average. All cows were maintained to graze daily on Megathyrsus maximus and supplemented with Morus alba ad libitum, being hand-milking at 0700 daily. Before analysis, the SCC was logarithmically trans-formed (log10). Then, PROC Mixed from SAS version 9.4 was used to evaluate all measurements. Results and Discussion: The MP had higher milk yields than PM cows (10.83 vs. 9.18 ± 0.38 kg/d; P = 0.003). Similar results were observed for fat-corrected milk (8.26 vs. 6.80 ± 0.34; P = 0.002), although the fat values did not differ between both groups (P = 0.86) being lower than referential values for these breeds (2.46 ± 0.16, on average). Additionally, no differences were observed in the other milk components (P = 0.65 to 0.85). Despite that, the somatic cell count (SCC) values indicated a statistical tendency in PM than in MP (1.89 vs. 2.13 ± 0.05; P = 0.07). Research Implications: Low-fat contents were observed in both groups, possibly due to the low quality of foods used in ruminant feeding. Correspondingly, the parity and advanced lactation conditioned the SCC contents. Therefore, further studies may be relevant in order to identify complementary factors that possibly could be more determinants. Originality/Value: The relevance and value of this research are very importance due to the main activity in this zone is livestock cattle.

Somatic Cell Count Evaluation in Early Lactation between Primiparous and Multiparous Bos indicus Cows

Using Bos indicus cows, a study examined the relationship between somatic cell count (SCC) and milk yield. For this study, one hundred fifty cows (Primiparous, PM, 75 and Multiparous, MP 75) in early lactation (days in milk, PM =134 ± 3; MP = 136 ± 5), milk production (9,88 kg/d, on average) of the creole breed Gyr lechers were enrolled. Before being assigned to each treatment, the SCC values were lower than 220,000 cells/mL, on average. All cows were maintained to graze daily on Megathyrsus maximus and supplemented with Morus alba ad libitum, being hand-milking at 0700 daily. Before analysis, the SCC was logarithmically transformed (log10). Then, PROC Mixed from SAS version 9.4 was used to evaluate all measurements. Regarding our results, the MP had greater milk yields than PM cows (10.83 vs. 9.18 ± 0.38 kg/d; P = 0.003). Similar results were observed for fat-corrected milk (8.26 vs. 6.80 ± 0.34; P = 0.002), although the fat values did not differ between both groups (P = 0.86) being lower than referential values for these breeds (2.46 ± 0.16, on average). No differences were observed in the other milk components (P = 0.65 to 0.85). Despite that, the somatic cell count (SCC) values showed a statistical tendency in PM than in MP (1.89 vs. 2.13 ± 0.05; P = 0.07). In conclusion, low-fat contents were observed in both groups, possibly due to the low quality of foods used in ruminant feeding. While that, the parity and advanced lactation conditioned the SCC contents. Therefore, other studies should be performed to identify more factors that could be determinants. Keywords: Milk, Tropical livestock, Udder health

Somatic Cell Count Evaluation in Early Lactation between Primiparous and Multiparous Bos indicus Cows

Using Bos indicus cows, a study examined the relationship between somatic cell count (SCC) and milk yield. For this study, one hundred fifty cows (Primiparous, PM, 75 and Multiparous, MP 75) in early lactation (days in milk, PM =134 ± 3; MP = 136 ± 5), milk production (9,88 kg/d, on average) of the creole breed Gyr lechers were enrolled. Before being assigned to each treatment, the SCC values were lower than 220,000 cells/mL, on average. All cows were maintained to graze daily on Megathyrsus maximus and supplemented with Morus alba ad libitum, being hand-milking at 0700 daily. Before analysis, the SCC was logarithmically transformed (log10). Then, PROC Mixed from SAS version 9.4 was used to evaluate all measurements. Regarding our results, the MP had greater milk yields than PM cows (10.83 vs. 9.18 ± 0.38 kg/d; P = 0.003). Similar results were observed for fat-corrected milk (8.26 vs. 6.80 ± 0.34; P = 0.002), although the fat values did not differ between both groups (P = 0.86) being lower than referential values for these breeds (2.46 ± 0.16, on average). No differences were observed in the other milk components (P = 0.65 to 0.85). Despite that, the somatic cell count (SCC) values showed a statistical tendency in PM than in MP (1.89 vs. 2.13 ± 0.05; P = 0.07). In conclusion, low-fat contents were observed in both groups, possibly due to the low quality of foods used in ruminant feeding. While that, the parity and advanced lactation conditioned the SCC contents. Therefore, other studies should be performed to identify more factors that could be determinants. Keywords: Milk, Tropical livestock, Udder health

Effects of maternal antral follicle count in Bos taurus indicus cattle on the genetic merit of male offspring and antral follicle count of female offspring

This study evaluated the effects of antral follicle count (AFC) in female cattle on offspring characteristics. Recently calved multiparous Bos indicus cows (Nelore; n = 222) were evaluated using ultrasonography on random days of their estrous cycle to determine the AFC and were classified into “low” (≤15 follicles), “intermediate” (≥16 and ≤ 29 follicles), and “high” (≥30 follicles) AFC groups. Weight and scrotal circumference (SC) of male offspring from these cows (n = 127) were determined from 20 to 27 months, and the data were added to a genetic evaluation program (economic total genetic merit, MGTe and TOP value) that uses the kinship matrix to evaluate the genetic relationship between animals. The AFC of female offspring from these cows (n = 95) was evaluated to analyze the relationship between the AFC of mothers and daughters. The effects of maternal AFC on the genetic merit of male and female offspring were analyzed using GLIMMIX and GLM, respectively. Correlations were assessed using the Pearson's coefficient. Male offspring of cows with high AFC had superior MGTe (P = 0.005) and TOP values (P = 0.01) than those from cows with low AFC. Additionally, the AFC of mothers was positively correlated with MGTe (R = 0.33; P < 0.0001) and negatively correlated with TOP values (R = −0.32; P < 0.0001). The SC (P = 0.01), but not body weight of the offspring (P = 0.46) was affected by maternal AFC. The daughters' AFC were correlated (R = 0.29; P = 0.004) with mothers' AFC and were influenced by maternal (P = 0.05) but not paternal (P = 0.77) effect. In conclusion, cows with high AFC produced males with greater MGTe, superior TOP values and higher SC. Maternal AFC did not influence the weight of male offspring but was correlated with the AFC of daughters.

Exploring uterine inflammation in postpartum primiparous precocious and conventional and multiparous Bos indicus beef cows.

This study aimed to compare the postpartum uterine dynamics of primiparous precocious (PP), primiparous conventional (PC) and multiparous conventional (MC) Bos indicus beef cows. For this purpose, PP (n = 8), PC (n = 18) and MC (n = 12) cows were enrolled in this study. These cows were evaluated at 20 and 10 days prepartum and weekly from parturition to 42 days postpartum (DPP). During this period, body weight (BW), subcutaneous fat thickness (SFT) and serum concentrations of glucose, β-hydroxybutyrate, albumin and haptoglobin were measured. Proportion of polymorphonuclear (PMN) cells, and abundance of mRNA transcripts of genes involved in uterine inflammation and uterine health were evaluated. The PP cows had lower (p < .05) BW and SFT than that for PC and MC cows during the study period. The serum concentration of albumin after 35 DPP was lower (p < .05) in PP cows. The PP cows had the highest proportion of PMN on 28 and 35 DPP compared to PC and MC cows. The relative mRNA abundance of IL-1β and IL-8 increased after 21 DPP in PP cows compared to the other groups. The PC had the highest, MC had an intermediate, and PP cows had the lowest relative abundance of IL10 mRNA. Overall, these findings indicated that uterine inflammation was more pronounced in PP cows. Moreover, based on the proportion of PMN and abundance of transcripts associated with inflammation in the uterus, PP cows may require a longer period to recover their uterine health after calving.

279 ReBreed21, a Rapid Reinsemination Program: Fertility in Bos Indicus Cattle of Different Parities

Abstract This study evaluated efficiency of a reinsemination program allowing timed AI (TAI) every 21 days (ReBreed21; RB21) vs. a traditional Resynch program in Nellore females (n = 2,085) of different parities. First TAI followed estradiol (E2)/progesterone (P4)-based synchronization, and was considered d0. For RB21 (n= 1,357), cows received P4 insert on D12. On D19, P4 was removed, followed by treatment with equine chorionic gonadotropin (eCG) and 0.6 mg E2 Cypionate (RB21+EC, n = 60) or nothing (RB21, n=687). On D21, Doppler ultrasound was used to determine CL blood flow [&amp;lt; 25%=nonpregnant (NP)] and NP cows received TAI immediately together with 25µg licerelin acetate (GnRH). A second RB21 program using the same groups was done in cows that received TAI on D21 to allow a third potential TAI on D42. Pregnancy diagnosis was performed on D33 after each TAI. Cows designated pregnant on D21 but NP on D33, were termed False-Positive (FP). On D33, all control (n = 728) designated NP and FP cows were resynchronized with P4+E2 protocol for the second TAI at D42. Data were analyzed with SAS and shown in Table 1. For all cows, there were no differences in the three groups (Control, RB21, RB21+EC) for pregnancy/AI (P/AI). In nulliparous heifers, cumulative pregnancies were greater for both RB21 groups compared to Controls at D21 or D42 of the breeding season. Primiparous cows had greater cumulative pregnancies at D21 but not D42. Primiparous cows at second TAI had lower P/AI in RB21 (34.2%) vs. Control (51.7%); however, RB21-EC (55.8%) was similar to Control. No other parities had differences between RB21 and RB21+EC. Multiparous cows had high fertility at first TAI [69.3% (418/603)] and no differences between groups in cumulative pregnancies (P = 0.23). Thus, ReBreed21 program increases the reproductive efficiency in Nulliparous and Primiparous but not Multiparous Bos Indicus cattle. Adding EC to RB21 program only improves P/AI in Primiparous cows.

Effects of eCG and FSH in timed artificial insemination treatment regimens on estrous expression and pregnancy rates in primiparous and multiparous Bos indicus cows

Effects were evaluated in Bos indicus cows of eCG and FSH on follicular growth, estrous expression, and pregnancy per artificial insemination (P/AI) as a result of fixed-time artificial insemination (TAI). In Experiment 1, extent of timing-of-ovulation synchronization among cows was evaluated after imposing an estrogen/progesterone-based treatment regimen. At progesterone device removal (D8), cows were administered: eCG, or FSH or served as untreated Controls. In Experiment 2, percentage of cows P/AI was evaluated when the Experiment 1-treatment regimen was imposed. On D10, all cows were artificially inseminated. In Experiment 3, cows were assigned to two treatment groups (Control and eCG) on D8 to evaluate percentage of cows P/AI and estrous expression. In Experiment 1, follicular dynamics were similar among treatment groups. In Experiment 2, follicular growth was greater (P = 0.0001) with the eCG treatment. There was an interaction of treatment × parity (P = 0.007) on percentage of cows P/AI. There was a greater percentage of primiparous cows P/AI in the eCG-treated than Control and FSH-treated cows. There was a greater percentage of eCG-treated multiparous cows pregnant as a result of TAI than Control cows. There was an interaction of treatment × parity (P = 0.005) on P/AI in Experiment 3, in which the eCG effect was more pronounced in primiparous cows. Treatment with FSH, therefore, was not as effective as eCG in stimulation of follicular growth or enhancing percentage of cows pregnant as a result of TAI. Physiological effects of eCG, however, were also more evident in primiparous cows.

The effect of clitoral stimulation post artificial insemination on pregnancy rates of multiparous Bos indicus beef cows submitted to estradiol/progesterone-based estrus synchronization protocol.

Clitoral stimulation after artificial insemination (AI) in beef cattle is a common practice utilized by AI technicians; however, the effect of clitoral stimulation during fixed-time AI (TAI) is still unknown. The objective of the present experiment was to evaluate the effect of clitoral stimulation on temperament responses and pregnancy rates to TAI in Bos indicus beef cows. A total of 1,186 multiparous Nellore cows across three different locations were assigned to an estradiol/progesterone-based estrus synchronization + TAI protocol (day -11 to 0). Cows were randomly assigned to receive either 3 s of clitoral stimulation (n = 602) or no clitoral stimulation (n = 584) immediately after TAI (day 0). Cow body condition score (BCS) was recorded on day -11. Estrus expression was evaluated based on estrus detection visual aid patch activation on day 0 (estrus, ≥50% activated; no estrus, <50% activated). Temperament was assessed by individual chute score based on a 5-point scale before TAI, and individual exit velocity was measured after clitoral stimulation. Pregnancy diagnosis was performed 30 d after TAI via transrectal ultrasonography. Pregnancy rate to TAI was positively affected by BCS (P < 0.01) and estrus expression (P = 0.03). Pregnancy rates of cows receiving clitoral stimulation did not differ (P = 0.39) from cows non-stimulated (47.5 ± 4.6% vs. 44.3 ± 4.6%, respectively). No interaction of clitoral stimulation and estrus expression was observed (P = 0.26). Chute score was positively correlated to exit velocity (P < 0.01; r = 0.29); however, clitoral stimulation did not affect exit velocity (P = 0.86). In summary, pregnancy rates to TAI are influenced by various factors and multiple strategies have the potential to increase the fertility of beef cows submitted to TAI; however, clitoral stimulation of Bos indicus beef cows did not improve TAI pregnancy rate.

PSII-38 The effect of clitoral stimulation post fixed-time insemination in Bos indicus beef cattle

Abstract The objective of this experiment was to evaluate the effect of clitoral stimulation post-insemination on pregnancy rates in Bos indicus beef cattle. A total of 1186 multiparous Nelore cows were assigned to an estradiol-based estrus synchronization + timed-AI protocol (FTAI, d 0), and randomly assigned to receive either 2 to 5 seconds of clitoral stimulation or no clitoral stimulation after artificial insemination. Estrus expression prior to AI was evaluated based on patch activation (estrus, ≥ 50% activated; no estrus, &amp;lt; 50% activated) using Estrotect Heat Detector and chute exit velocity after AI was evaluated. Individual exit score was calculated within each group by dividing exit velocity into quintiles and assigning cows with a score from 1 to 5 (1 = slowest; 5 = fastest). Artificial insemination was performed by 7 different technicians. Pregnancy diagnosis was performed 30 days after FTAI via transrectal ultrasonography. Overall pregnancy rate at day 30 was 46.0% (545/1186). Clitoral stimulation had no beneficial effect (P = 0.42) on pregnancy rate of multiparous cows when compared to those not stimulated (47.5% ± 4.6 vs. 44.3% ± 4.6). Cows that expressed heat at d 0 (n = 602) had a greater (P &amp;lt; 0.01) pregnancy rate compared to no heat expression (37.6% ± 4.7 vs. 60.6% ± 4.6), but no effect of the clitoral stimulation was observed on pregnancy rate in cows that did or did not express heat (P &amp;gt; 0.05). Furthermore, clitoral stimulation did not affect exit score (P = 0.67) of cows after FTAI. No effect of the technician was observed on pregnancy rate when clitoral stimulation was applied or not (P = 0.21). In summary, clitoral stimulation was not a useful managerial tool to improve pregnancy rate in multiparous Bos indicus cows submitted to FTAI using estradiol-based protocols.

171 Follicular and luteal characteristics and pregnancy rates in Bos indicus suckled cows treated with two oestradiol/progesterone-based protocols with a prolonged pro-oestrus

An experiment was designed to evaluate the effect of the length of insertion of a progesterone (P4)-releasing device on follicular and luteal characteristics and pregnancy rates to fixed-time AI (P/FTAI) in Bos indicus cows treated with oestradiol/P4-based treatments with a prolonged pro-oestrus. Multiparous Bos indicus suckled beef cows (n=659), 60-90 days postpartum, with a corpus luteum (CL) or at least one follicle ≥8mm in diameter and with a body condition score between 2 and 3.5 (1-to-5 scale) were synchronised using three treatments. On Day 0, all cows received 2mg of oestradiol benzoate (Sincrodiol, Ourofino) and an intravaginal device with 1g of P4 (Sincrogest, Ourofino). The P4 device was removed on Day 6 in cows in the J-Synch 6 group (n=195) and on Day 7 in cows in the J-Synch 7 group (n=262) and conventional group (n=202). All cows received 500μg of cloprostenol (Sincrocio, Ourofino) and 400IU of equine chorionic gonadotrophin (SincroeCG 6000UI, Ourofino) at the time of P4 device removal. Cows in the conventional treatment group also received 0.5mg of oestradiol cypionate (SincroCP, Ourofino) at the same time. In addition, all cows were tail-painted for oestrous detection (CeloTest, Biotay). Cows that had lost ≥50% of the tail paint 62-66h (J-Synch groups) or 48-52h (conventional group) after device removal were FTAI at that time. Cows not showing oestrus by 62-66h (J-Synch groups) or 48-52h (conventional group) received 10μg of GnRH (Sincroforte, Ourofino) at the same time and were FTAI 8h later. A subset of 20 cows per group was also examined using ultrasonography (Mindray DP50 Vet) every 12h from the time of device removal to determine the time of ovulation, 6 days after ovulation to determine CL diameter, and 30 days after FTAI to determine P/AI. Data were analysed using the GLM Mixed procedure (InfoStat). The results are shown in Table 1. The diameter of the dominant preovulatory follicle was larger and the interval from device removal to ovulation was longer in cows in the J-Synch groups compared with those in the conventional group (P&amp;lt;0.05). Furthermore, the diameter of the CL was larger and P/FTAI was higher in cows in the J-Synch 7 group compared with those in the J-Synch 6 and conventional groups. In conclusion, delaying the removal of the P4 device by 1 day (i.e. Day 7 vs. Day 6) in the J-Synch groups and prolonging the pro-oestrus period by not giving oestradiol cypionate at P4 device removal (i.e. J-Synch 7 vs. conventional) resulted in a larger preovulatory follicle and CL and higher P/FTAI in Bos indicus suckled cows. Table 1.Mean (±s.e.m.) diameter of the preovulatory follicle (P/Foll) and corpus luteum (CL), interval from progesterone (P4) device removal to ovulation, and pregnancy rates to fixed-time AI (P/FTAI) in Bos indicus suckled cows Treatment P/Foll diameter, mm CL diameter, mm Interval to ovulation, h P/FTAI,% (n) J-Synch 6 15.5±0.3a 18.7±0.8a 83.0±4.0b 41.0 (80/195)a J-Synch 7 16.4±0.2b 21.9±0.8b 86.0±3.0b 52.0 (136/262)b Conventional 13.8±0.2a 16.8±0.9a 64.0±3.0a 37.1 (75/202)a a,bDifferent superscripts denote differences between means or P/FTAI.

Effects of eCG are more pronounced in primiparous than multiparous Bos indicus cows submitted to a timed artificial insemination protocol

The effects of eCG on follicular growth, ovulation, and pregnancy per artificial insemination (P/AI) in multiparous and primiparous Bos indicus beef cows submitted to timed artificial insemination (TAI) were evaluated in three experiments. In experiments 1 (follicular responses; n = 64), 2 (follicular growth and ovulation rate; n = 662), and 3 (P/AI; n = 2092), cows submitted to TAI were assigned to receive one of two treatments on Day 8 of the synchronization protocol: control (no additional treatment) or eCG (300-IU of eCG intramuscularly). In experiment 1, largest follicle (LF) diameter on Day 8 (P = 0.56) and the interval from progesterone (P4)-device removal to ovulation (P = 0.79) did not differ between treatments. However, the maximum diameter of the LF (P = 0.05) and ovulation rate (P = 0.03) were greater in cows that received eCG. In experiment 2, the diameter of the LF on Day 10, follicular growth, and ovulation rate were greater in eCG-treated cows (P < 0.01). However, CL diameter was similar between treatments (P = 0.11). In experiment 3, there was a treatment-by-parity interaction (P = 0.003) on P/AI, such that treatment with eCG was more effective in primiparous cows. In conclusion, eCG treatment resulted in increased final follicular growth, ovulation rate, and fertility in B indicus cows submitted to TAI protocols, especially in primiparous cows.

Effect of restricted suckling on the onset of follicular dynamics and body condition score in Brahman cattle raised under tropical conditions

With the aim of evaluating the effect of restricted suckling on the onset of follicular dynamics and body condition, multiparous Bos indicus cows were distributed in two groups. One group (RS=36) was subjected to a scheme of restricted suckling starting at 21days postpartum. Calves were allowed to suckle once per day for a period of two h whilst the control group (C=18) remained with their dams at all times. At calving, body condition score, back fat thickness and body weight had similar values (p>0.05) for both groups. By day 85 postpartum both groups had recorded losses in body weight. The cows in the continuous group formed a greater (p<0.05) number of follicles of class size <6mm in both periods before and after synchronization. The proportion of cows showing estrus and ovulation before 45days, was not different (p>0.05). The number of cows that exhibited estrus after 45days, was greater (p<0.05) in RS than C group, 72.2% and 55.5%, respectively. Same situation (p<0.05) occurred in cows that ovulated, 88.8 and 66.7%, for groups RS and C, respectively. The subset in the intensive observations showed that the size of the bigger follicle was larger (p<0.05) for RS cows than C cows from 36h after CIDR withdrawal. At 57h, the size of the biggest follicle recorded was not different between groups (p>0.05). A regime of restricted suckling favors the earlier growth of follicles and the prompt restoration of ovarian activity.

A pre-synchronization program at early postpartum might increase the chances of Bos indicus cows cycling prior to 50 days regardless of the length of calf separation.

The aim of this study was to establish if pre-synchronization would enhance the number of animals cycling prior to conventional breeding at 45 days irrespective of the length of calf separation. Multiparous Bos indicus cows were allotted in four groups (n = 10). Control group (C) dams remained with their calves; groups G24, G48 and G72, which were partially weaned for 24, 48 and 72 h, respectively, were estrus synchronized using a controlled internal drug. These procedures were performed at 25 days and again at 45 days postpartum. The number of follicles, presence of a corpus luteum and back fat thickness (BFT) were determined by ultrasound. The proportion of cows with estrus and ovulation at day 25 postpartum was statistically different between the control and treated groups, with the values being 20, 60, 50 and 70 for the control, G24, G48 and G72 groups respectively (P < 0.05). At days 45 postpartum, the proportion of cows with estrus and ovulation was different in group G48 compared with the other groups (P <0.05). The average BFT and body condition score for the four experimental groups in the two periods were similar (P >0.05). Animals with a higher proportion of follicles from 17 to 21 mm, BFT values above 3.5 mm and a regular body condition were significantly different regardless of whether the dams remained with their calves or were separated, regardless of the length of this event. It can be concluded that (1) a pre-synchronization program at day 25 could trigger the onset of ovarian activity and facilitate a breeding program at day 50 and (2) temporary weaning enhances the effect of a pre-synchronization program.

Strategies to improve fertility in postpartum multiparous Bos indicus cows submitted to a fixed-time insemination protocol with gonadotropin-releasing hormone and prostaglandin F2α1

In Exp. 1, we evaluated the effects of 2 lengths of progesterone exposure [CIDR (controlled intravaginal drug release); 7 vs. 14 d] before a modified CO-Synch protocol [50.0-microg injection of GnRH 6.5 d before a 25.0-mg injection of PGF(2alpha) followed by another injection of GnRH and fixed-time AI (TAI) 2 d after PGF(2alpha)], with or without temporary weaning (TW) before GnRH treatments, on fertility of suckled multiparous Bos indicus cows (n = 283) and on calf performance. Timed AI pregnancy rates for cows receiving 7 d CIDR + TW, 7 d CIDR, 14 d CIDR + TW, and 14 d CIDR were 53, 47, 46, and 41%, respectively (P > 0.10). Calves submitted to two 48-h TW 6 d apart had decreased mean BW at 240 d (187.9 +/- 2.7 vs. 195.5 +/- 2.7 kg; P < 0.05), but BW at 420 d was not affected by TW (240.1 +/- 5.1 kg). In Exp. 2, we evaluated the effect of no treatment and treatment with or without a CIDR insert between GnRH and PGF(2alpha) treatments of a modified CO-Synch protocol on pregnancy rate to TAI, and throughout a 90-d breeding season in suckled multiparous Bos indicus cows (n = 453). The inclusion of a CIDR between first GnRH and PGF(2alpha) treatments of a modified CO-Synch protocol did not improve pregnancy rate (29 and 33% for cows receiving CO-Synch + CIDR and CO-Synch protocol, respectively), and cycling cows had poorer TAI pregnancy rates than anestrous cows treated with either synchronization protocol (21.7 vs. 40.7%; P < 0.05). However, regardless of treatment with CIDR, cows submitted to TAI protocol had greater (P < 0.05) pregnancy rates at 30 (54.8 vs. 11.2%), 60 (72.1 vs. 38.8%), and 90 d (82.0 vs. 57.9%) of breeding season than untreated cows.

Ultrasonography as Aid for Early Pregnancy Diagnosis in Zebu Cattle in a Natural Mating Programme

Galicia, L.L., Estrada, K.S, Galina, C.S, Pérez, G.E, Romero, J.J. and Molina, S.R. 2006. Ultrasonography as aid for early pregnancy diagnosis in Zebu cattle in a natural mating programme. J. Appl. Anim. Res, 29: 53–58. To utilise ultrasonography in Zebu cattle to test early pregnancy, multiparous Bos indicus cows (n=74) were allocated with 2 mature Brahman bulls, which were replaced with new ones every four weeks. Cows were bled for radioimmunoassay progesterone analysis at the time of ultrasound and four days prior or after this event. The efficiency of the ultrasound findings and progesterone levels were compared wit' Kappa index using the computer programme (WIN) EPISCOPE. Ultrasound precision for early pregnancy diagnosis was 96%. Moreover, animals not clearly defined as pregnant, following examination revealed that only 54% were actually pregnant. The efficiency to detect the lack of ovarian activity was only 25% as revealed by progesterone concentrations lower than 1ng/ml. In contrast, the association between a detectable CL by ultrasound and progesterone values higher than 1ng/ml was 90%. The incidence of embryonic death was 15.4%. Based on these results the efficacy for detecting early pregnancy by ultrasound and the presence of an active CL is satisfactory, whereas the precision to detect non-cycling animal is questionable and the incidence of embryonic death is high.