Non-pregnant Cows Research Articles

Effects of twice daily compared with split-time estrous detection on pregnancy percentage in recipient beef cows

Objectives were to compare pregnancy percentages per embryo transfer (P/ET) in recipient beef cows following twice daily compared with split-time estrous detection and to determine associations of dominant follicle diameter, CL volume and progesterone concentrations. All cows (n = 695) were treated to synchronize time of estrus among cows using a CIDR + Select-Synch treatment regimen and randomly assigned to twice-daily or split-time estrous detection (CS-DEET or CS-SEET, respectively). Cows in the CS-DEET group were observed twice daily (eight times) for estrus until 96 h after the time of PGF2α administration, whereas cows in the CS-SEET group were observed twice (64 and 84 h after PGF2α). In 280 recipient cows, blood sampling (for progesterone) and ultrasonographic assessment of dominant follicle diameter were conducted 48 h after the time of PGF2α administration. At 7 d after estrus, the CL was imaged and there was transfer of a frozen-thawed embryo into cows with a CL ≥ 1.5 cm. There were positive correlations between follicle diameter and CL volume (rs = 0.827; P < 0.001) and CL volume and progesterone concentration (rs = 0.680; P < 0.001). Progesterone and CL volume differed between cows in CS-SEET and CS-DEET groups P < 0.05), however, percentage P/ET for cows in the CS-SEET and CS-DEET groups did not differ (P > 0.1). Dominant follicle diameter, CL volume and progesterone concentrations were greater in pregnant compared with nonpregnant cows. In conclusion, percentage P/ET did not differ when there was twice daily and split-time estrous detection highlighting the value of this approach in beef enterprises.

Licking and agonistic interactions in grazing dairy cows as indicators of preferential companies

The quality of the social environment should be studied as one of the welfare components of dairy herds. Licking and preference between cows are important socio-positive experiences in this context.The aims of this study were: 1) to describe the behaviours temporally associated with social licking in grazing dairy cows, 2) to measure the association of social licking with social hierarchy and gestational state and 3) to compare social licking between preferred mates – cows that are more often in close proximity – and other mates. Six commercial Jersey herds, averaging 24.6 ± 5 lactating cows per herd, and managed on a rotational grazing system year-round, were enrolled in the study. Herds were kept constant for at least 30 d before data collection, and at four days before data collection the herds were habituated to the data collection routine. The behaviours of all cows within each herd were observed through direct observation for six days between milking, from 8:00 am to 3:00 pm. A total of 148 cows were observed for 42 h each during the study period. Licking events and agonistic interactions were observed continuously, and the individual instigator and receptor participating in each event were recorded. All agonistic interactions were registered, and a sociometric matrix was developed for each herd. Scan sampling (every 6-min) was used to register behaviours of each individual cow and its closest neighbours. Licking was a widespread behaviour in the studied herds, registered in 94.5 % of the cows and occurring most often around 10:00, during ingestive behaviours. Social lickings were most often observed immediately before drinking or mineralizing, and immediately after idling or ruminating. Social hierarchy was not associated with the number of social lickings. Pregnant cows received 1.63 more lickings than non-pregnant cows but didn’t perform more. Furthermore, older cows performed and received more lickings than primiparous cows. Social licking interactions were higher (1.89 vs. 0.62; p ≤ 0.01) between preferential mates than the average for the herd. Similarly, agonistic interactions between preferential mates was higher (1.97 vs. 1.52; p ≤ 0.01) than observed among the average herd. Our results reveal that social licking is widespread among herds and suggests an association with social preferences when cows are on pasture, which may be related to affinity among cows. Preferred mates also showed greater number of agonistic interactions.

Changes in hematological parameters in sahiwal cows reaching to estrus following PGF2α (double) injections

PGF2α being a luteolytic agent regulates the lifespan of the corpus luteum on the ovary and is therefore, used for estrus synchronization. The present study was conducted on 6 non-inseminated, non-pregnant, anestrus (pre or post-service) or repeat breeder Sahiwal cows. Blood samples were collected after double injections of PGF2α for haematological analysis on day 0, 11, 12, 13 & 14. TLC (thousands/ µl), TEC (millions /µl), Hb (%), PCV (%), MCV (fl), MCH (pg) and MCHC (g/dl) were evaluated by using an automatic blood analyser. The study indicated no significant changes in the TEC, Hb, PCV, MCV, MCH and MCHC during estrus synchronization with double PGF2α protocol. The alteration in blood picture of cow on day of induced estrus (day 14) was non significant decrease in TEC, Hb and PCV.

Effect of treatment of phantom cows with a progesterone-based synchrony programme

ABSTRACT Aim: To determine the effect of a progesterone-based synchrony programme on the daily hazard of conception and the probability of being pregnant at the end of the seasonal mating period in cows not observed in oestrus within 35–49 days of insemination and that were diagnosed non-pregnant (phantom cows) on seasonally calving New Zealand dairy farms. Secondary aims were to determine the prevalence of phantom cows and estimate the proportion of phantom cows with a functional corpus luteum (CL) at enrolment. Methods: Phantom cows from 14 New Zealand commercial dairy farms were enrolled in a randomised, controlled trial. Cows that were artificially inseminated ≤14 days after mating start date and were not subsequently detected in oestrus, were presented for pregnancy diagnosis approximately 49 days after mating start date. Non-pregnant cows were diagnosed as phantom cows and randomly allocated to treatment and control groups. A milk sample was collected for progesterone assay to determine the presence of a functional CL. Treatment consisted of an injection of buserelin and insertion of an intravaginal device containing progesterone on Day 0, injections of dinoprost and equine chorionic gonadotrophin, and removal of the intravaginal device on Day 7, injection of buserelin on Day 9, and fixed time artificial insemination on Day 10. Treatment group cows were then mixed with bulls for the remainder of the seasonal mating period. Cows allocated to the control group were mated naturally by bulls. Statistical models were constructed to determine the effect of treatment on the daily hazard of conception and the probability of being pregnant at the end of the seasonal mating period. Results: A total of 378/4,214 (9.0%) cows presented for pregnancy diagnosis were diagnosed as phantom cows. A functional CL was diagnosed in 257/362 (71.0%) phantom cows. Median predicted enrolment to conception intervals were 33 (95% CI = 30–45) and 30 (95% CI = 28–33) days, for cows in the control and treatment groups, respectively. The odds of being pregnant at the end of mating were 1.70 (95% CI = 1.34–2.17) times greater for treated phantom cows than untreated phantom cows. Estimated marginal mean proportion pregnant at mating end date were 59.5 (95% CI = 47.9–70.1)% and 71.5 (95% CI = 62.6–79.0)% for control and treatment group cows, respectively. Conclusions: Treatment with a progesterone-based synchrony programme significantly increased the probability of phantom cows being pregnant at the end of the seasonal mating period.

Relationships between early postpartum nutritional and metabolic profiles and subsequent reproductive performance of lactating dairy cows

The objective of this study was to examine the relationship between early postpartum nutritional and metabolic profiles in lactating dairy cows and subsequent pregnancy to first artificial insemination (AI), pregnancy by 150 d in milk (DIM) and pregnancy loss after first AI. A blood sample was collected between 2 and 14 (median = 9) DIM from 869 lactating Holstein cows to determine serum concentrations of metabolites, minerals, and liver enzymes. Associations between analytes and fertility were determined using an adjusted odds ratio (OR). Overall, pregnancy to first AI, pregnancy by 150 DIM and pregnancy loss after first AI were 37.9, 65.8 and 11.2%, respectively. Compared to cows pregnant to first AI, non-pregnant cows had higher (P < 0.05) serum concentrations of aspartate aminotransferase (AST; 92.3 ± 1.6 vs. 84.6 ± 2.0 U/L), non-esterified fatty acid (NEFA; 0.73 ± 0.02 vs. 0.54 ± 0.02 mmol/L), and haptoglobin (0.77 ± 0.04 vs. 0.60 ± 0.05 g/L), and lower (P < 0.05) serum concentrations of Mg (0.86 ± 0.02 vs. 0.89 ± 0.02 mmol/L) and cholesterol (2.1 ± 0.03 vs. 2.4 ± 0.04 mmol/L). Cows non-pregnant by 150 DIM had lower (P < 0.05) serum concentration of Mg (0.86 ± 0.02 vs. 0.88 ± 0.02 mmol/L) and higher serum concentration of haptoglobin (0.82 ± 0.1 vs. 0.63 ± 0.09 g/L) than cows pregnant by 150 DIM. Cows that lost their pregnancy after first AI had greater serum concentrations of haptoglobin than those that did not undergo pregnancy loss (1.1 ± 0.09 vs. 0.5 ± 0.05 g/L; P < 0.01). The odds of pregnancy to first AI (OR; 95% confidence interval [CI]) decreased with increased serum concentrations of AST (OR = 0.99; 95% CI = 0.98–1.00), NEFA (OR = 0.54; 95% CI = 0.37–0.79) and haptoglobin (OR = 0.80; 85% CI = 0.66–0.96) and increased with inreased concentrations of Mg (OR = 3.24; 95% CI = 1.09–9.62) and cholesterol (OR = 1.24; 95% CI = 1.02–1.54). Increased serum concentrations of Mg (OR = 3.06; 95% CI = 1.02–9.20) and haptoglobin (OR = 0.92; 95% CI = 0.69–0.97) were associated with greater and lower odds of pregnancy by 150 DIM, respectively. Only increased concentrations of haptoglobin (OR = 1.58; 95% CI = 1.13–2.20) were associated with increased odds of pregnancy loss after the first AI. In summary, greater early postpartum serum concentrations of AST, NEFA and haptoglobin were associated with reduced fertility, but the opposite was observed for serum concentrations of Mg and cholesterol. In addition, serum concentrations of haptoglobin were positively associated with pregnancy loss.

Cow-calf management practices in Mexico: Reproduction and breeding

Beef cattle breeding has developed in extensive grazing systems in Mexico, concerning the livelihood of over one million families and affecting the use of natural resources. Reproductive efficiency is a major determinant of both the environmental impact of the herd, and the economic viability of the cow-calf production system. However, as reproductive traits have low heritability, reproductive efficiency can be largely influenced by herd management practices. Thus, a questionnaire was administered as personal interviews to 3280 producers, to investigate the prevalence of practices that could directly influence the reproductive outcome of their cattle. Results show that year-round breeding (93%) and natural service by the bull (97.4%) are the most common mating methods. However, only 41% of producers evaluate the breeding soundness of their bulls, and diagnostic testing for specific reproductive diseases of the sires is barely performed in 20% of the farms. The main declared reason for replacing the bull is old age (26.8%), which is followed by to avoid inbreeding (68.4%). Less than 10% of the operations use methods for the synchronization of the estrous cycle, and most farmers breed their heifers for the first time after 2 years of age (73%). Diagnosis of pregnancy is performed in merely 31% of operations, with 23% of the producers declaring to discard non-pregnant cows. Energy or protein feed supplements are provided to the cattle in 63% of the production units, whilst mineral supplements are given in 79% of the farms. Calves are typically weaned between 6 months and a year of age (85%). Only 16% of operations vaccinate against brucellosis and 17.5% against other reproductive diseases (IBR-DVB-VSR and Leptospirosis). The present study showcases a low frequency of adoption of basic reproductive management practices by cow-calf operations in Mexico. Advancement of these practices, as well as implementation and promotion of associated technologies, denotes an area of opportunity to improve the reproductive efficiency of the national herd.

Characterization of Vaginal Microbiota Associated with Pregnancy Outcomes of Artificial Insemination in Dairy Cows.

The profitability of the dairy and beef industries is largely affected by the actually achieved reproductive efficiency. Although a large proportion of cows worldwide are bred by artificial insemination (AI) services, many potential factors affecting the outcome of pregnancy by AI remain to be addressed. In the present study, we investigated the vaginal microbiota by high-throughput sequencing of 16S rRNA gene and analyzed their association with differential pregnancy outcomes (i.e., pregnant vs. nonpregnant) of multiple AI services in dairy cows. Sequencing of the V3-V4 region totally produced 512,046 high-quality sequences that were computationally clustered into 2,584 operational taxonomic units (OTUs). All OTUs were taxonomically assigned to 10 bacterial phyla. There were statistically significant differences among the three AI service times (T1, T2 and T3) with respect to the Shannon index and number of observed OTUs (p < 0.05). Bray-Curtis distance-based PCoA analysis also revealed that T2 group could be significantly distinguished from T1 and T3. However, no significant difference between the pregnant and nonpregnant cows was found in confidence regarding both alpha diversity and beta diversity. These results could help us better understand the possible influence of vaginal microbial community on pregnancy outcomes of AI service in cows.

A reproductive management program aimed at increasing reinsemination of nonpregnant dairy cows at detected estrus resulted in similar reproductive performance to a program that favored timed artificial insemination

The objective of this experiment was to compare time to pregnancy and proportion of cows not pregnant 210 d after first service for cows managed for second and subsequent artificial insemination (AI) services with a reproductive management program that promoted reinsemination at detected estrus (AIE) or a program that promoted timed AI (TAI). After first service, lactating Holstein cows were blocked by parity and randomly assigned to d 32 Resynch (D32R; n = 464) or AIE Resynch (AIER; n = 512). To determine the effect of management strategies on time to pregnancy and cows not pregnant by the end of a 210 d at-risk period after first AI service, cows remained in AIER and D32R until pregnancy or herd exit. Cows in D32R received a GnRH treatment 32 ± 3 d after AI (first treatment intervention; FTI). Nonpregnancy diagnosis was conducted 7 d later by transrectal ultrasonography when nonpregnant cows with a corpus luteum (CL) ≥15 mm completed the Resynch protocol (PGF2α, 56 h later GnRH, and 16 to 18 h later TAI) and cows without a CL (NoCL cows) were enrolled in a PreG-Ovsynch protocol (GnRH, 7 d later GnRH, 7 d later PGF2α, 56 h later GnRH, and 16 to 18 h TAI) to receive TAI. For the AIER treatment, nonpregnant cows with a CL ≥15 mm observed by transrectal ultrasonography 32 ± 3 d after AI (i.e., FTI) received PGF2α to induce estrus. Cows not AIE within 7 d were enrolled in Resynch (GnRH, 7 d later PGF2α, 56 h later GnRH, and 16 to 18 h TAI). Cows in the NoCL group in AIER were enrolled in PreG-Ovsynch. Detection of estrus was performed based on visual observation of behavioral signs of estrus and tail-paint removal. Binomial data were analyzed with logistic regression and time to event data with Cox's proportional regression. After the FTI, a greater proportion of cows were AIE in AIER than D32R (36.0 vs. 11.9%) and more cows were AIE within 7 d of the FTI for AIER (25.0%) than D32R (4.8%). Overall pregnancy per AI at 68 ± 3 d after AI did not differ (AIER = 35.5% vs. D32R = 34.7%). The hazard of pregnancy up to 210 d after first AI for all cows enrolled (hazard ratio = 1.04, 95% CI 0.90 to 1.19) and for cows that received treatments only (D32R = 308, AIER = 349; hazard ratio = 1.00, 95% CI 0.85 to 1.19) did not differ. We conclude that a program aimed at increasing the proportion of cows reinseminated at detected estrus by treatment with PGF2α at 32 ± 3 d after AI may be an alternative strategy for dairy farms that prefer or need to inseminate more cows at detected estrus rather than by TAI.

Comparison of ruminal digestibility of Origanum onites L. leaves in dairy buffalo and cows.

This experiment evaluated the ruminal digestibility of Turkish oregano leaves in dairy buffalo and cows. Ruminally cannulated, multiparous Brown Swiss cows (n = 3) and water buffalo (Bubalus bubalis; n = 3) were used in the experiment. The ad libitum basal diet was balanced to NRC requirements for a dry, nonpregnant multiparous dairy cow (680kg) and consuming 12.8kg of DM/day. Air-dried, ground, weighed oregano leaves were inserted in the rumen of all animals before the morning feeding within heat-sealed nylon bags (4 replicates per treatment and time point). After incubation (4, 8, 24, 48, and 72h), dry matter (DM), crude protein (CP), aNDFom, and ADFom concentrations were determined and compared to initial leaf chemical composition. The means for in situ disappearance (ISD, %) of DM, aNDFom, and ADFom did not differ between the species, but ISD of CP was greater in buffalo than the cows (P = 0.05) after 72h incubation. The lag time of kinetic degradation curves, the potentially degradable fraction (b), hourly degradation rate (c), and undegradable fraction were similar between species. The immediately degraded fraction (a) and effective digestibility (ED) of CP were greater in buffalo than the cows (P = 0.04), but the a fraction and ED of other nutrients showed no differences between the species. In conclusion, CP of oregano leaves are degraded more rapidly in the rumen of dairy buffalo than cows, primarily due to a large difference in the rapidly soluble CP fraction in the buffalo.

The Number and Types of Bacteria in the Bali Cattle’s Vagina during Estrus and Pregnant

Bali cattle have very good potential for meat and calf supply, because they have good adaptability with good quality reproductive properties. However, good reproductive nature is threatened by diseases caused by bacteria. This study aims to determine the number and types of bacteria in the vagina of Bali cattle that are estrus and pregnant. Sample using vaginal swabs from 30 cows. The sample consisted of 10 swabs from non-estrus and not pregnant (control / normal) cattle, 10 swabs from estrus cows, and 10 swabs from pregnant cows. After the swab is carried out using a cotton bud, the results of the swab are stored in Stuart transport media. Samples planted in blood media to be identified and the number of colonies counted, then followed by Gram staining and biochemical tests then the results were presented descriptively. The result is the highest number of estrous cow colonies (1034 colonies), compared to non-estrous and non-pregnant cows (407 colonies) and pregnant (376 colonies). This type of bacteria is dominated by Klebsiella sp. (42.85%), Eschericia coli (28.7%), Streptococcus sp. (14.28%) and Bacillus sp. (14.28%).

Early resynchronization of non-pregnant beef cows based in corpus luteum blood flow evaluation 21 days after Timed-AI

The study aimed to verify whether a hormone protocol started at Day 13 (D13) after Timed Artificial Insemination (TAI) influences the conception rate. Nelore cows (primiparous and multiparous) from two commercial beef farms (n = 1,431) were first TAI (D0). Timed AI was performed in lots (TAI Lots) ranging from 187 to 346 cows. On D13, regarding the TAI lot, cows were assigned for either receiving (Resynch group, n = 1,002) or not (Control group, a subset of approximately 30%, n = 429) another hormone protocol for resynchronization. The same hormone protocol was used for the first TAI and for the resynchronization, except for 1 mg instead of 2 mg of estradiol benzoate (EB) at the begging of the protocol. Eight days later (D21), the Resynch group was checked for corpus luteum blood flow by color Doppler ultrasonography, and in those detected as non-pregnant, the protocol was completed and a 2nd TAI was performed at D23. Pregnancy diagnosis was later (D30) performed by B-mode ultrasonography in the control group and confirmed in the presumptive pregnant cows from the 1st TAI of the Resynch group. The remaining cows were checked for pregnancy 30 days after the 2nd TAI (experimental Day 53). The statistical model to explain conception rate considered the effects of Group (Control or Resynch), Farm, Parity (primiparous or multiparous), Sire, Technician (who perform AI), TAI Lot and pertinent interactions (Group*Parity, Group*Farm and Group*TAI Lot). The statistical analyses of the model were performed using the Proc Glimmix (SAS virtual University Edition). The conception rate for the 1st TAI was similar (P > 0.4) between Control (50.3%, 216/429) and Resynch group (52.6%, 527/1002). The positive predictive diagnostic on D21 showed high relation with PD30 (90.7%, 527/581). In Resynch group, non-pregnant cows (n = 421, 1002 minus 581) were re-inseminated. The conception rate of the 2nd TAI (42.8%, 180/421) was affected (P < 0.002) by side effects of the Farm (48.5 vs. 33.1%) and Parity (51.2 vs. 40.3%, for multiparous vs. primiparous, p < 0.001). Nevertheless, after the 2 TAIs of the Resynch group, the cumulative conception rate was 70.5% (707/1002). In conclusion, the early resynchronization of cows with a low (1 mg) EB dose and progesterone device at D13 after TAI can be used as a strategy to reduce conception interval in beef cattle, and thus to increase the number of pregnant cows from artificial insemination after the breeding season.

Body composition changes of crossbred Holstein × Gyr cows and conceptus during pregnancy

This study aimed to evaluate the effects of plane of nutrition and advancing days of pregnancy (DP) on maternal body composition and fetal development. Differing planes of nutrition were established by 2 feeding regimens (FR): ad libitum (AL) or maintenance (MA). Sixty-two nonlactating multiparous Holstein × Gyr cows with average body weight of 480 ± 10.1 kg and an age of 5 ± 0.5 yr were used. Cows were divided into 3 groups: pregnant (n = 44), nonpregnant (n = 12), and baseline reference cows (n = 6). The 56 pregnant and nonpregnant cows were randomly allocated into 2 different FR: AL or MA. Cows fed at MA received 1.15% of their body weight on a dry matter (DM) basis, receiving corn silage and a concentrate-based diet at a ratio of 93:7 on a DM basis. Reference group cows were slaughtered at the beginning of the experimental period to estimate body composition and empty body weight. To evaluate the effects of DP, pregnant and nonpregnant animals were slaughtered at d 140, 200, 240, and 270 of gestation. Feeding regimen affected maternal tissue composition. Days of pregnancy affected fresh weight (FW), DM, and energy content, but no differences were observed for crude protein (CP) and ether extract (EE) because of DP. Feeding regimen affected mammary gland components (CP, EE, and energy content), but not fresh or dry weights. Days of pregnancy influenced almost all mammary gland components except energy content. Regarding the uterus, FR affected only fresh and dry weights; however, DP affected every uterus component measured. The only interaction between FR and DP in this study was observed for placental FW. Cows fed AL on d 270 presented the same placental FW as cows at MA and AL on d 200 and 240. Further, pregnant cows fed at MA on d 270 had greater placental FW than cows fed AL at this day. Days of pregnancy, but not FR, influenced the composition of fetal fluids in pregnant cows. Finally, cows fed at MA had greater FW for the fetus than cows fed AL; however, fetus composition changed over DP. The FW, DM, EE, and energy content increased until d 270, but CP decreased. In conclusion, the novelty of our data presents how changes due to FR and DP occur in maternal tissues and the conceptus.

Effects of human chorionic gonadotropin and intravaginal progesterone device treatment after artificial inseminations on the reproductive performance of normal and repeat breeder lactating dairy cows.

We examined the effects of human chorionic gonadotropin (hCG) treatment on Day 5 (Day 0 = day of artificial insemination: AI) and intravaginal progesterone device (IVPD) treatment from Day 5 to 19 on the conception and detection rates of return to estrus (re-estrus) in lactating dairy cows. A total of 306 cows from a commercial dairy farm were divided into the following three groups on Day 5: non-treatment group (n = 128), untreated; hCG group (n = 71), 3,000 IU hCG was administered (intramuscularly); IVPD group (n = 107), IVPD was inserted into the vagina from Day 5 to 19. Re-estrus detection was performed up to Day 25. Pregnancy was diagnosed by rectal palpation between Day 50 and 60. There was an interaction between treatment and AI number (P < 0.01) on the conception rate of first-AI. For cows with more than three AIs, the IVPD treatment (66.7%) was more effective than the non-treatment (23.1%) (P < 0.05). The re-estrus detection rate was significantly (P < 0.05) higher in the IVPD group (60.7%) than that in the non-treatment group (41.4%) and tended (P < 0.1) to be higher than that in the hCG group (37.8%). Our results suggested that the conception rate can be improved by IVPD treatment, especially in cows with more than three AIs. In addition, IVPD treatment can induce higher estrus expression up to 25 days after AI in non-pregnant cows.

Reproductive performance of northern Australia beef herds. 2. Descriptive analysis of monitored reproductive performance

A population-based epidemiological study was conducted between 2007 and 2011 and involved 78 northern Australian commercial beef-breeding herds and in excess of 56 000 cattle concurrently monitored. Cow reproductive performance was described from the biannual assessment of fetal age and lactation status. Both novel and well established measures of performance were used within four broad country types and included the following: percentage of lactating cows pregnant within 4 months of calving; percentage of cows pregnant within an approximate 12-month reproductive cycle (annual pregnancy); fetal and calf loss between confirmed pregnancy and weaning; percentage of cows contributing a calf at weaning and percentage of non-pregnant females retained for re-mating. The results from the present study described the variation in reproductive performance of commercial beef herds across northern Australia and defined typical and achievable levels of performance. The results from the study suggest that a weaning rate of 66% is a more realistic target level of performance for the Northern Forest, while weaning rates of at least 75–80% are realistic for other country types. Female-cattle performance was much lower in the Northern Forest than in the other country types. In absolute terms, there were 15–20% fewer surviving mated cows contributing a calf at weaning in an annual production year and ~4% more missing pregnant cows, which was associated with the ~20% higher retention of non-pregnant cows for re-mating. The reproductive performance of herds varied substantially among and within country types, with a 20–30% variation in reproduction rates and 5–15% variation in fetal and calf loss for half of the herds in all regions. Further analyses were performed and identified the major causes of this variation and are reported in subsequent papers within this series. The results from the present study appear to suggest that substantial opportunities to increase the reproductive performance of northern beef herds exist, providing that the causes of this variation are able to be identified and alleviated.

Antioxidative and oxidative profiles in plasma and saliva of cows in different ages and hormonal status.

The aim of this study was to evaluate changes in the antioxidant status and oxidative stress parameters in plasma and saliva in order to investigate the physiological conditions of dairy cows. Blood and saliva were collected from clinically healthy female calves (n = 18), sexually mature, non-pregnant cows (n = 19), and pregnant dairy cows (n = 15). Spectrophotometric and spectroflurimetric analyses were carried out in the body fluids of these animals. The level of total antioxidant capacity (TAC) in plasma reached the lowest (p < 0.05) value in the group of sexually mature, non-pregnant cows (2.375 ± 0.500 μmol/g). A significant negative correlation (tau b = - 0.248, p < 0.05) was found between TAC values detected in plasma and saliva of examined animals. The highest (p < 0.05) mean values of thiol groups were detected in both plasma (0.007 ± 0.0015 mmol/g) and saliva (0.276 ± 0,116 mmol/g) of mature, non‑pregnant cows. Conversely, the highest (p < 0.05) levels of formylokinurenine concentration were detected in saliva (11.535 ± 3.785 μg/mg) and plasma (0.133 ± 0.0237 μg/mg) of pregnant dairy cows. A significant positive correlation (tau b = 0.255, p < 0.05) was also found between the bityrosine content detected in plasma and saliva of the examined cows. In conclusion, although with regards to antioxidant/oxidative parameters saliva reflects the content of plasma only in part, however it shows age-related differences that can be used in the description of the physiological status of cows.

Prostaglandin F&lt;sub&gt;2α&lt;/sub&gt; induced luteolysis is delayed but not prevented by acute administration of luteotropic drugs in lactating nonpregnant Holstein cows

Inadvertent use of prostaglandin F2α (PGF2α) in pregnant cattle could result in luteolysis and pregnancy loss. Using a nonpregnant cow model, we determined if luteotropic agents could counteract luteolytic effects of PGF2α. Ovarian status of 20 lactating nonpregnant Holstein cows was synchronized using an Ovsynch protocol and ovulation confirmed by transrectal ultrasonography 48 hours after the second gonadotropin releasing hormone (GnRH). Eight days after ovulation, 25 mg of dinoprost (native PGF2α) was administered IM to induce luteolysis. Five minutes after PGF2α, cows were treated IM with gonadorelin (GnRH, 100 μg; n = 5), human chorionic gonadotropin (hCG, 1,000 IU; n = 6), porcine pituitary luteinizing hormone (pLH, 25 mg; n = 5), or saline (control, 2 ml; n = 4). Blood samples were collected before PGF2α (0 hour) and at 1, 6, 12, 18, 24, 30, 36, 42, 48, 60, 72, and 84 hours after PGF2α to monitor subsequent luteal activity by measuring plasma progesterone concentrations. Although none of the treatments counteracted the luteolytic action of PGF2α, the rate of decline in plasma progesterone within 1 hour after PGF2α was greater (p = 0.04) in control than in GnRH, hCG, and pLH (2.2 versus 0.2, 0.3, and 0.1 ng/ml/hour, respectively). In addition, pLH-treated cows tended (p = 0.07) to have greater overall mean plasma progesterone for up to 84 hours (1.6 ± 0.2 ng/ml) than other treatments combined (1.1 ± 0.1 ng/ml). In the present study, giving GnRH, hCG or pLH 5 minutes after PGF2α administration was not effective in countering luteolytic effects of PGF2α. Nevertheless, pLH treatment tended to delay PGF2α induced luteolysis, which warrants further investigation.

Markers of lipid metabolism and antioxidant system of organisms of cows depending on their physiological state

The study is aimed at determining the etiopathogenesis of reproductive ability disorder among high-producing cows. For this purpose, a group of cows amounting 37 heads was formed following the principle of analogous pairs. The cows were inseminated during the first estrum after calving, and then their blood was drawn using Monovette system taking into account sterility terms. In the drying off period, the blood was drawn 1-4 days before calving and during the first day after calving. Totally 253 blood samples were tested. Proceeding from the results, cows were divided into two groups. The first group included 20 cows impregnated after the first insemination; the second group included 17 not impregnated cows. Later the blood was drawn providing for the parturition process and postpartum period. Blood values were investigated by commonly accepted methods using certified equipment. The study showed that cows during the early gestation have lipid metabolism, lipid peroxidation and antioxidant system state significantly differing from those among non-pregnant cows. During the gestation, cows have the level and class of general lipids reducing, as well as the accumulation of lipid peroxidation products. Cattles with retained placenta have low lipid metabolism and higher level of peroxidation within interlactation period. After the calving, this difference tends to widen. The obtained data can be used for elaboration of measures preventing post-parturient complications by applying agents with antioxidant properties.

Identification of Estrogen Levels in Dairy Cows Based on MUN Levels And Pregnancy Rates

This study aimed to determine the effect of Milk Urea Nitrogen (MUN) levels as an indicator of protein intake to estrogen levels and pregnancy status in dairy cows. Eighteen productive heifers from wagir district, Malang were collected out from criteria. Thus, they were groups based on MUN levels and reproductive status. Feeding is done in the same pattern. Blood drawing for estrogen level were analized by Enzyme Linked Immunosorbent Assay (ELISA). Milk extraction for analysis of urea levels using the Barthelot method. Pregnancy examinations were carried out three months after Insemination. Data analysis were processed using SPSS (Statistical Package for the Social Sciences) for Windows programs. The results showed that non-pregnant cow had MUN levels from 16-28 mg/dL and high estrogen levels at time of estrus were the same as estrogen levels in pregnant cow. It can be concluded that the same feed pattern different produces MUN levels, estrogen and pregnancy status, depending on the efficiency of nitrogen utilization in the body and physiological health of individual dairy cows.

Short communication: Accuracy of corpus luteum color flow Doppler ultrasonography to diagnose nonpregnancy in dairy cows on day 21 after insemination

The main objective of this study was to determine the accuracy of corpus luteum color flow Doppler ultrasonography (CLCFDU) to diagnose nonpregnant dairy cows 21 d after insemination. A secondary objective was to determine the accuracy of other indirect tests such as corpus luteum size and progesteronemia. Data from 1,632 Holstein cows (10 commercial herds) were used for the analysis in this prospective cohort study. The herds were visited weekly by a veterinarian and an animal health technician. During farm visits, cows were examined on d 21 after insemination using transrectal B-mode ultrasonography to quantify the presence and size of the corpus luteum. After identification of the corpus luteum, CLCFDU was performed and scored as D0, D1, D2, or D3 when 10% or less, between 11 and 30%, between 31 and 60%, or 61% or more of the corpus luteum surface was colored, respectively. A blood sample from coccygeal vessels was also collected to quantify progesteronemia. Farmers were blinded to these findings and no intervention was performed following examination. On d 32 after insemination, the cows were examined by the regular herd veterinarian using transrectal palpation and B-mode ultrasonography to determine whether the cows were pregnant or not (the reference test). Statistical analyses were conducted using 2 × 2 contingency tables. The apparent prevalence, sensitivity, specificity, positive predictive value, and negative predictive value of CLCFDU for predicting nonpregnancy were 22.0, 36.6, 99.0, 98.1, and 52.0%, respectively, when using D0 only as the diagnostic criterion; they were 47.2, 76.4, 94.8, 93.5, and 73.8%, respectively, for D0+D1 criteria. The same measures for cows with a corpus luteum <15 mm were 8.0, 11.7, 97.5, 86.9, and 43.4%, respectively, and they were 51.9, 67.4, 70.4, 76.6, and 60.0%, respectively, for progesteronemia <1 ng/mL. The measures of accuracy of CLCFDU to identify nonpregnant cows on d 21 after insemination were high, and the apparent prevalence varied depending on the diagnostic criteria used. The measures of accuracy of corpus luteum size (<15 mm) for the same purpose were high; however, apparent prevalence was low. The measures of accuracy of progesteronemia (<1 ng/mL) were low. In conclusion, CLCFDU had excellent accuracy to diagnose nonpregnancy in dairy cows on d 21 after insemination.

Effects of water restriction on behaviour, feed and water intake of Ongole crossbred cows at various physiological conditions in the smallholder farmers

This study aimed to assess the behaviour, feed and water intake of Ongole Crossbred cows on various physiological conditions at the smallholder farmers with water restrict provided. Ten cows (3 non-pregnant, 4 pregnant and 3 lactations) were observed for their eating and drinking behaviour as well as feed and water intake for 8 consecutive days. The behaviour observed including eating time, frequencies of eating, drinking, defecation and urination. Behaviour and consumption were analysed using a one way ANOVA and continued with the DMRT test. The results showed that there were significant differences in the level of water intake for cows on different physiological status (P <0.05). The frequencies of feeding and urination of non-pregnant and pregnant cows were lower (P <0.05) than lactation cows. Non-pregnant cows spend less time eating than pregnant and lactation cows. The non-pregnant cows also less defecated (P <0.05) than the pregnant and lactating cows. It is concluded that raising of cows with restricted water providing shows that lactation cows have the most water intake, the longest eating time, and the frequency of eating the most frequency of defecation and urination.