Estrus Detection Rate Research Articles

Follicular persistence, oestradiol level and conception on the first and second day of oestrus and influence of thermal stress in cross-bred dairy cows manifesting prolonged oestrus

Increasing incidence of prolonged oestrus reported in cross-bred dairy cows bred through artificial insemination (AI), is attributed to various causative factors and underlying mechanisms. The present study was to assess the pattern of follicular growth, oestrogen secretion, and conception on the first and second day of oestrus and to understand the influence of thermal stress as a causative factor for oestrus prolongation. The year-round study involved 52 crossbred cows intensively managed under a hot humid climate, during their second and third months postpartum. Animals were examined for the status of ovarian follicles, oestrogen level, and conception to AI on Day 0 and Day 1 of oestrus confirmation and the findings were compared across seasons. While oestrus detection rate (ODR) and conception of AI were lowest during the summer season attributable to maximum TS, better ODR (P<0.05) and more prolonged oestrus (P<0.01) occurred during the seasons of favourable climate having least TS and better green fodder availability. Besides, the occurrence of larger follicles and almost similar oestradiol levels on Day 0 and Day 1 of oestrus, better conception rate for double AI (63.16 %) than total AI (48.48 %) indicated prolonged oestrus and involvement of delayed ovulation among the causation. Comparison of the seasonal pattern of follicular growth, oestrogen level, and conception to AI between Day 0 and Day 1 further clarifies the influence of TS and increased milk production as the potential contributors to the occurrence of prolonged oestrus in cross-bred cows under the hot humid tropical climate. Keywords: Crossbred cow, Oestrogen, Prolonged oestrus, Thermal stress

Effects of dietary supplementation with Vitamin A, D3, E, and Garlic on heat detection, pregnancy rate, and serum profile in anestrus dairy cows

Anestrus poses substantial challenges for dairy industries worldwide. This research aims to evaluate the effect of oral supplementation with garlic alone, vitamins A, D3, E alone, and their combination on heat detection, pregnancy rate and serum profile in anestrus dairy cows. Using a completely randomized design, this study, conducted over 327 days, evaluated 72 anestrus-affected cows, which were divided into four groups. T0 (Control) received only normal saline; T1 with vitamin A,D3,E; T2 with Garlic and T3 integrated with A, D3, E + Garlic in drinking water. Results demonstrated that the treatment groups exhibited significantly higher estrus signs (p<0.05) compared to the control. The pregnancy rate was also increased (P=0.059), especially in the T3 group which had the highest heat detection (55.55%), conception (70%), and pregnancy (38.88%). In comparison, the heat detection rate for T1 was 44.44%, while the conception rate for T2 was 66.66%. Additionally, T0 exhibited the least proportion across all parameters. Additionally, the elevated BUN (Blood Urea Nitrogen) and blood glucose levels observed in non-responsive (those not showing signs of heat) cows at 32.51 and 43.65 mg/dl respectively, compared to responsive cows (those showing signs of heat) with levels of 22.40 and 51.34 mg/dl. These findings suggest a potential association between these blood parameters and the cyclicity of dairy cows. These findings highlight that oral supplementation with vitamin AD3E+Garlic significantly improves the heat detection rate and pregnancy rate than only administering vitamin AD3E or Garlic with anestrus in dairy cattle.

TTOOLS FOR IMPROVING REPRO ON DAIRY FARMS

The studies presented in this article are part of the PTF of the Kazakhstan Ministry of Agriculture. Most consultants, when dealing with herd fertility problems, advise first setting specific goals (S), measurable (M), achievable (A), relevant (R), and time-bound (T) – SMART goals. Each farm has different assets, goals, and challenges and therefore a consultant must tailor their recommendations to the farm and avoid generalizations or textbook recommendations based on national averages. To create the standards for feeding, reproduction, and maintenance of dairy, during 2021-23 improved diets, assessed animal welfare, and reproduction data was collected monthly, the basis of the collected data in the article shows the dynamics of the fertility of cows in one of the basic farms participating in Execution of the program. By improving the conditions of feeding and maintenance, the fertility of cows had a positive dynamic. One of the important indicators is the number of calves per 100 cows from 77 calves in 2021 increased to 86 in 2023. The number of cows with an elongated dry period from 14.7% decreased to 6.3%. Pregnancy Rate increased by 2 times from 11.9% to 20.8%. The mortality rate of calves also decreased from 23.2% in 2021 to 6.7% in 2023. Introducing the system for heat detection cuts the heat detection rate coefficient, the indicator has grown to 54% from a low 23% in 2021. In general, we can conclude that by improving the level of feeding and maintenance, the fertility of the cows had positive dynamics.

Discrimination strategy using machine learning technique for oestrus detection in dairy cows by a dual-channel-based acoustic tag

Timely identification of cows in heat is a fundamental issue in dairy farming. Although current studies have confirmed that several cow vocalisation characteristics can be used for oestrus identification, the reliability and practicability of oestrus detection methods are limited due to background noise, a lack of data support for sound feature selection, and the unsatisfactory effectiveness of vocalisation recognition algorithms.To overcome these predicaments, a dual-channel recording device and a sound event extraction method were developed in this study. The experimental results in respect of 62 Holstein dairy cows showed that the sound sample recording accuracy was 80.4%, and the noise filtering accuracy was 94.3%, indicating the effectiveness of the vocalisation extraction algorithm in a noisy farm environment. Moreover, two unique sound features with remarkable discrimination ability, i.e., the number of consecutive vocalisations and the maximum consecutive times, were used to improve the effectiveness of oestrus detection. The Friedman test, the Spearman rank order correlation coefficient, and the Kruskal-Wallis test were used to obtain the combination of features with the most optimal discrimination. Subsequently, a dual-LSTM (Long Short-Term Memory) joint discriminant strategy based on optimal combinations was proposed to promote oestrus detection performance. The results of the blind test on the vocalisation data of 20 oestrus cows and 11 non-oestrus cows demonstrated that the oestrus detection rate of the discrimination strategy reached 100%, and had a temporal advantage over the activity-index-based method in determining the onset of oestrus.The improvements of the selection and-based oestrus detection method mainly included accurately extracting individual cow vocalisations, supplementing the explicability of feature selection, and enhancing the refinement of oestrus recognition. Meanwhile, it is of positive significance for applying sound acquisition devices in oestrus detection. Furthermore, combining sound identification with other automated detection techniques appears to be a promising method for promoting the oestrus detection rate.

A Non-Contact Cow Estrus Monitoring Method Based on the Thermal Infrared Images of Cows

Traditional methods of cow estrus monitoring technology are not suitable for the current needs of large-scale, intensive and welfare-based farming. There is a need to improve the detection rate of cow estrus and to reduce the emergency response caused by wearing contact devices. Furthermore, it is necessary to verify the practical effectiveness of the LOGISITC and SV (support vector machine) models for modeling cow estrus. In this paper, we have proposed a non-contact cow estrus monitoring method based on the thermal infrared images of cows and have proposed a lab-color-space-based feature extraction method for the thermal infrared images of cow eyes and vulvas. The test subjects were 10 Holstein cows, monitored on a fixed basis, to determine the best segmentation contour. The LOGISTIC and SVM (support vector machine) models were used to establish the cow estrus model using the thermal infrared temperature variation in cows in estrus and cows not in estrus. The experimental results showed that the heat detection rate of the LOGISTIC-based model was 82.37% and the heat detection rate of the SVM-based model was 81.42% under the optimal segmentation profile. The highest temperature in the eye and vulva of cows was the input, and the recall rate was above 86%. The heat monitoring method based on thermal infrared images does not cause stress to cows and meets the needs of modern dairy farming for welfare breeding.

The effect of progesterone length in timed AI in ewes.

This study aimed to evaluate the reproductive performance of ewes submitted to timed AI protocol with 7 (D7) or 9 (D9) days of progesterone. A total of 220 crossbred ewes (Doper × Santa Ines) were distributed in the treatments according to body weight (52.67 ± 11.76kg), body condition score (2.5 ± 0.8; scale of 1-5), and the female category (multiparous, nulliparous and primiparous). Ewes received an intravaginal device of 0.3g of progesterone (CIDR® Easy breed) on day 0, keeping in ewes for 7 or 9days, which were the experimental treatments. At the time of P4 withdrawal, ewes received 300IU of eCG (Novormon®) and 6.70mg of dinoprost tromethamine (Lutalyse®). Insemination by laparoscopy was performed between 46 and 59h after device removal, lasting from 1 to 5min/ewe, which did not differ between protocols. The estrus detection rate was higher in the 9-day protocol compared to the 7-day protocol (82% and 65%, respectively, P = 0.0096). However, the 7-day protocol tended to increase pregnancy rate on the TAI compared to the 9-day protocol (45% and 33%, respectively, P = 0.09). The plasma concentration of progesterone at device removal was higher in the 7-day protocol than in the 9-day protocol (2.35 and 1.22ng/mL, respectively, P = 0.04). We conclude that reducing the length of the estrus synchronization protocol to 7days is recommended, which improved the reproductive response in ewes.

Evaluating automated infrared thermography and vulva exposure tracking as components of an estrus detection platform in a commercial dairy herd

The primary objective of this study was to develop an automated infrared thermography platform (Estrus BenchMark) capable of measuring skin temperature and tail movements as a means of identifying cows in estrus. The secondary objective was to evaluate the accuracy of Estrus BenchMark to detect estrus compared to in-line milk progesterone (P4) analysis (Herd Navigator System) in a commercial dairy herd managed under a robotic milking system. Data were collected on forty-six cows from 45 to 120 d after calving. Cows were flagged in estrus when milk P4 fell below 5 ng/mL. The Estrus BenchMark true positive estrus alerts (Sensitivity; Se%) were compared to Herd Navigator System estrus alerts at different time-windows (±12 h, ±24 h, ±48 h, and ±72 h) relative to the Estrus BenchMark estrus alerts for all the estrus alerts (AE) and confidence-quality estrus (CQE; >80% quality) alerts identified by Herd Navigator System. The Estrus BenchMark captured skin temperature and tail movements resulting in vulva exposure (left tail movements, LTail; right tail movements, RTail; and pooled tail movements, PTail) for each milking event. Skin temperature tended to increase when the milk P4 concentration (Least-Squares Means ± SE) dropped for AE (estrus day [d 0]; P4; 3.51 ± 0.05 ng/mL, Skin temperature; 33.31 ± 2.38 °C) compared with d −7 (P4; 20.22 ± 0.73 ng/mL; Skin temperature: 32.05 ± 3.77 °C). The increase in skin temperature, however, was significant in cows with CQE > 80% at d 0 (32.75 ± 0.29 °C) compared to d −7 (31.80 ± 0.28 °C). The prevalence of tail movements to expose vulva was greater (P = 0.01) in AE at d 0 (LTail: 62.50%; PTail; 68.75%; and RTail: 56.25%) compared with d −7 (LTail: 18.75%; PTail: 9.37%: and RTail: 9.37%), and d +4 (LTail: 9.37%; PTail: 9.37%; and RTail: 12.5%). Moreover, the higher prevalence of tail movements at d 0 was observed in cows with CQE > 80% (LTail; 65%, PTail; 80%, and RTail; 70%) compared to those with CQE < 80%. The highest Estrus BenchMark Youden index (YJ; 0.45), diagnostic odds ratio (DOR; 9.04), and Efficiency (0.77) were achieved for AE in a ±48 h window and at ±72 h window for CQE (YJ; 0.66, DOR; 25.29, and Efficiency 0.76) relative to Herd Navigator System estrus alerts. The highest Estrus BenchMark resulted in 58% estrus detection rates for AE and 80% for cows with CQE compared to the Herd Navigator System.

Business analysis of IRT, Visual observation, and Ovsynch as breeding strategies in Alberta dairies

The dairy industry is searching for new technologies to address low (<50%) estrus detection. However, the lack of information on the potential economic benefits regarding new technology implementation has led some dairy producers to continue using conventional estrus detection methods (e.g. visual observation of standing to be mounted). The objective of this study was to compare the costs of infrared thermography (IRT), visual observation (VO) and ovulation synchronization (Ovsynch: OVS) as breeding strategies at different accuracy levels (Sensitivity [Se], Specificity [Sp]) and pregnancy rates (PR). The costs associated with Breeding, Feeding, Operation Costs, Return to Equity and Culling Risk per estrus detection rate (ER; 30–100%, conception rate for OVS; 30–100%), PR [PR per Parity group; 1–2 (50%), 3–4 (43%), and >4 (41%)], and ER accuracy determined the potential financial benefit of each breeding method for a representative farm. Breeding Cost results (Canadian dollars per cow; CAD/cow) showed a higher cost of OVS (138.99) as compared to VO (115.78) and IRT (127.69). Pregnancy Costs were affected by Breeding Cost; however, ER had a significant effect on PR expense for each method, IRT (ER; 30%: 210.38; 100%: 132.19), VO (ER; 30%: 205.93; 100%: 129.39), and OVS (ER; 30%: 247.21; 100%: 155.33). The minimum Se level with a positive Financial Effect for IRT and VO was 60% with a Sp of 100%, and for the OVS was Se 65% and Sp 100%. However, when the Se was 100% a positive Financial Effect was observed with a minimum Sp of 85% for IRT and 75% for VO. Culling Risk was reduced if ER increases differently depending on the parity group. Implementing of IRT as an estrus detection method yields a competitive breeding cost compared to VO and OVS. Further, breeding methods must accomplish at least ∼60% accuracy to have a positive net return.

Evaluation of infrared thermography combined with behavioral biometrics for estrus detection in naturally cycling dairy cows

Low estrus detection rates (>50%) are associated to extended calving intervals, low economic profit and reduced longevity in Holstein dairy cows. The objective of this study was to evaluate the accuracy of infrared thermography and behavioral biometrics combined as potential estrus alerts in naturally (not induced) cycling dairy cows housed in a tie-stall barn. Eighteen first lactation cows were subjected to transrectal ultrasonography to determine spontaneous ovulation. The dominant follicle (DF) disappearance was used retrospectively as an indirect indicator of ovulation, and to establish the estrus period (48–24 h prior the DF disappearance). Raw skin temperature (Raw IR) and residual skin temperature (Res IR) were recorded using an infrared camera at the Vulva area with the tail (Vtail), Vulva area without the tail (Vnotail), and Vulva’s external lips (Vlips) at AM and PM milking from Day 14 until two days after ovulation was confirmed. Behavioral biometrics were recorded on the same schedule as infrared scan. Behavioral biometrics included large hip movements (L-hip), small hip movements (S-hip), large tail movements and small tail movements to compare behavioral changes between estrus and nonestrus periods. Significant increases in Raw IR skin temperature were observed two days prior to ovulation (Vtail; 35.93 ± 0.27 °C, Vnotail; 35.59 ± 0.27 °C, and Vlips; 35.35 ± 0.27 °C) compared to d −5 (Proestrus; Vtail; 35.29 ± 0.27 °C, Vnotail; 34.93 ± 0.31 °C, and Vlips; 34.68 ± 0.27 °C). No significant changes were found for behavioral parameters with the exception of S-hip movements, which increased at two days before ovulation (d −2; 11.13 ± 1.44 Events/5min) compared to d −5 (7.30 ± 1.02 Events/5min). To evaluate the accuracy of thermal and behavioral biometrics, receiver operating characteristic curve analysis was performed using Youden index (YJ), diagnostic odds ratio, positive likelihood ratio (LR+), Sensitivity, Specificity and Positive predicted value to score the estrus alerts. The greatest accuracy achieved using thermal parameters was for Res IR Vtail PM (YJ = 0.34) and L-hip PM (YJ = 0.27) for behavioral biometrics. Combining thermal and behavioral parameters did not improve the YJ index score but reduced the false-positive occurrence observed by increasing the diagnostic odds ratio (26.62), LR+ (12.47), Specificity (0.97) and positive predicted value (0.90) in a Res IR Vtail PM, S-hip AM, S-hip PM combination. The combination of thermal and behavioral parameters increased the accuracy of estrus detection compared to either thermal or behavioral biometrics, independently in naturally cycling cows during milking.

Comparison of efficacy of Ovsynch protocol to single PGF2α administration in treatment of individual dairy cows with post-service subestrus.

The aim of this study was to evaluate the efficacy of the Ovsynch protocol in the treatment of post-service subestrus in individual dairy cows compared to a single administration of PGF2α. The study was performed on 517 Polish Friesian Holstein cows with post-service anestrus over four years in 3 dairy herds under a herd health program. Cows (n=240) diagnosed ultrasonographically as non-pregnant and with a mature corpus were treated with a single PGF2α administration and inseminated at detected estrus. Cows without corpus (n=277) were treated with the Ovsynch protocol. The estrus detection rate after PGF2α administration, percentages of cows pregnant after the treatment and at day 260, intervals from parturition to treatment and from treatment to conception and pregnancy loss rates were calculated. The overall percentage of cows pregnant after treatment did not differ between animals treated with the Ovsynch protocol and with PGF2α (38.9% vs. 42.5%; p>0.05). In herd A the percentage of cows pregnant after treatment was significantly lower (p⟨0.05) for the Ovsynch group than for the PGF2α group (30.2% vs. 61.2%). In contrast, in herd C the percentage of cows pregnant after treatment was significantly higher (p⟨0.05) in the Ovsych group than in the PGF2α group (39.6% vs. 28.8%). The overall estrus detection rate after administration of PGF2α was 59.6%. However, it was significantly lower (p⟨0.05) in herd C (44.7%) than in herds A (79.6%) and B (76.3%). The overall pregnancy loss rate ranged from 5.1% to 13.3% and did not differ significantly between herds and treatment groups (p>0.05). In conclusion, Ovsynch protocol can be a useful alternative for treatment of post-service suboestrus in individual cows in dairy herds with insufficient oestrus detection.

Estrus Detection Methods in Dairy Animals- Advances and the Prospects: A Review

Fertility over the past few decades is of serious concern in the dairy industry. Fertility of a dairy herd is determined by composite factors, which in turn depends upon effective management strategies. The reproductive potential of the animals need to be exploited to its maximum to achieve optimum production in a herd. The single most important factor that limits the establishment of pregnancy and survival of the embryo in dairy cattle and buffaloes and thereby reproductive efficiency of a herd is proper estrus detection, Pedometer or activity meter is a motion switches devices within which steps followed by animals are recorded. Activity meters can be attached to the neck or leg of cows and they may be read by a receiver and processed by computer in a milking parlour. By implementing automatic detection system, heat detection rates can be improved, for improving reproductive efficiency. The activity monitoring techniques can also be used to detect the silent ovulation which is helpful for improving efficiency and accuracy of estrus.

Estrus signs in Holstein Friesian dairy cows and their reliability for ovulation detection in the context of visual estrus detection

The aim of the present study was to determine the frequency of estrus signs in housed dairy cows and to compare their reliability in relation to visual estrus detection, including all signs of estrus, which can be observed like cows’ behavior (especially standing to be mounted) and physiological processes like the appearance of vaginal mucus. For the study, the estrous behavior of 139 cows was observed and reliability rates (RR) for each estrus sign were calculated. Visual estrus detection was performed three times daily for 30 minutes each and began at Day 21 postpartum and ended at Day 40 of gestation. Estrus signs were evaluated according to a three-point scoring system. Additionally, estrous cycle monitoring was carried out by transrectal ultrasonography and serum progesterone analyses. Ovulation was confirmed by the presence of a sonographically detected ovulation and a progesterone concentration of ≤ 1.0 ng / mL within 24 hours before or after ovulation, and served as strong indication for the results of the visual estrus detection (Ov-estrus).It turned out that besides standing heat (standing-to-be-mounted by another cow for about three to seven seconds), the most reliable estrus signs were an increase in activity and participation in group activities of other cows in estrus (RR: 93.4 %), head resting in the back area of ​​other cows for more than two seconds (RR: 86.7 %) and mounting of herd members (RR: 93.8 %). Though standing heat was the most reliable estrus sign (RR: 100.0 %), it was only observed in 22.3 % of all detected Ov-estrus events. By using these estrus signs for visual heat detection, a heat detection rate of 52.2 % was reached.In conclusion, since only half the estruses can be detected by visual estrus detection, it is essential to use especially the estrus signs with high RR in order to ensure sufficient estrus detection.

Effects of Beta-carotene Administration on Fertility in Lactating Dairy Cows

Background: Beta-(β-) carotene, is the precursor to vitamin A, in particular, has some potential benefits on reproduction. The main objective of this study was to investigate the efficacy of β-carotene administration on fertility following either prostaglandin F2 alpha (PGF) induced estrus or Ovsynch protocol in lactating dairy cows.Methods: Cows with at 47±3 postpartum days were divided into two groups: β-carotene group (βC, n=139) was treated with injectable β-carotene while untreated cows served as control (CON, n=227). In both groups, PGF was administered and heatmount detectors were applied at 54±3 days postpartum. Cows detected in estrus after PGF were inseminated. Cows that had not been detected in estrus were divided into two groups 7 days after PGF administration; βC-OVS (n=137) and CON-OVS (n=89). Ovsynch protocol was initiated 4 days after β-carotene administration.Result: The estrus detection rate was similar between the βC and CON groups (P = 0.19). Pregnancy per AI (P/AI) on d 31 was also similar between groups (P = 0.93). In the Ovsynch protocol, ovulation to the first GnRH and ovulatory follicle diameter at the time of insemination did not differ between groups. No difference was observed in P/AI at d 31 (P = 0.13). The results of this study indicated that β-carotene administration had no effect on fertility either PGF induced estrus or Ovsynch protocol in dairy cows.

Relationship between quality of facilities, animal-based welfare indicators and measures of reproductive and productive performances on dairy farms in the northwest of Spain

The aim of the present study was to evaluate the effect of facility comfort level on animal-based welfare indicators as well as on productive and reproductive parameters of 187 dairy farms in the northwest of Spain. Fifty-eight facility-based parameters, which included both housing facilities and management parameters, were evaluated in each farm and used to classify the 187 farms in 5 groups (from 1: top farms to 5: worst farms). Animal-based welfare indicators and reproductive and productive parameters were compared among farm groups. Lameness score significantly differed (p < .005) in top farms (67% of cows having normal gait) versus groups 4 (55%) and 5 (53%). The proportion of cows with dirty lower legs and udder was lower (p < .05) in top farms (80% and 31%, respectively) than in groups 4 (92% and 51%) and 5 (95% and 56%). Other animal-based indicators were not different among farm groups. Heat detection rate was higher (p < .001) in top farms (56.5%) versus groups 4 (51%) and 5 (47%), and milk production/cow/day was also significantly higher (p < .001) in top farms (34.4 L) versus groups 3 (31.2 L), 4 (30.5 L) and 5 (27.4 L). Other reproductive or productive parameters were not different among farm groups. Facility-based measures were compared only between the top and worst farms. In top farms, most facility-based parameters met the welfare-related objectives, whereas in the worst farms only a few facility-based parameters met the welfare objectives. Highlights Fifty-eight facility-based parameters, including housing measures and some management practices, were evaluated and scored in 187 dairy farms. Top-performing farms (i.e. with the best scores) had lower incidence of lameness and of cows with dirty legs and udder than poor-performing farms. Top-performing farms had higher rates of heat detection and higher milk production/cow/day than poor-performing farms.

Heat Detection, Conception and Pregnancy Rates of Holstein Cows in Central Chile

Although the HDR of this particular Chilean cattle population may be considered good, there is still room for progress in order to improve fertility of Chilean dairy herds.

Evaluation of pregnancy diagnosis using ultrasonography in goats

Pregnancy status in 250 goats was determined by transabdominal ultrasonography. The registered hospital cases were divided into groups A (mated naturally; 88); B (postpartum reported unmated; 112) and C (pubertal unmated; 50). Animals found to be non-pregnant and free of uterine infection were labelled Group D and divided into synchronized (S) and control (NS) groups. GnRH followed byPGF2α nine days later was injected i.m. in group S, and NS group were allowed natural mating. All mated goats were checked monthly for pregnancy using ultrasonography. Pregnancy was diagnosed in 45.5, 4.5 and 0% from naturally mated, postpartum reported unmated and pubertal unmated cases, respectively. The oestrus detection and pregnancy rates varied significantly (P&lt;0.001) between synchronized (n = 96; 70.8 and 54.4%, respectively) and NS group (n = 96: 54.0 and 28.6%, respectively). Pregnancy rates significantly varied in different months in gestation (P&lt;0.05). Fetal viability rate was low in 1st month of pregnancy compared to other months (2nd, 3rd and &gt;3rd). The confirmation of expected date of delivery (EDD) was low in 1st month of gestation compared to other months. Transabdominal ultrasonographic scanning helps to confirm pregnancy in goats. From 2nd month of gestation ultrasound scanning confirms pregnancy with viable fetus (83.3%). At 3rd month of pregnancy, this technique determined the EDD up to 94.2%. The Bangladesh Veterinarian (2019) 36(1 - 2): 42-48

Evaluation of activity meters for estrus detection: A stochastic bioeconomic modeling approach

Although estrus detection makes a relevant contribution to the reproductive performance of dairy cattle, studies on the economic evaluation of automatic estrus detection systems are rare. The objective of the present study is to provide an economic evaluation of activity meters used for estrus detection. The effect of different estrus detection rates on gross margins was modeled with SimHerd (SimHerd A/S, Viborg, Denmark). The analysis considers all costs associated with the investment in activity meters. The economic evaluation was carried out through simulation of Simmental herds with yearly milk yields of 7,000 or 9,000 kg and Holstein Friesian herds with yearly milk yields of 9,000 or 11,000 kg, each with herd sizes of 70 or 210 cows. Furthermore, we distinguished between 2 investment scenarios. In scenario 1, only cows are equipped with activity meters for estrus detection, whereas scenario 2 assumes that cows and heifers are equipped with activity meters. Because existing empirical information for some variables shows significant variability (estrus detection rates, time for estrus detection), they were modeled with distributions using the Monte Carlo method in @RISK (Palisade Corporation, Ithaca, NY), allowing us to model a probability distribution of net returns (NR) of investment in activity meters for estrus detection. The simulation results show that the average NR of investment in activity meters for estrus detection over all scenarios ranges from +€7 to +€40 per cow per year for the Simmental breed, and from +€19 to +€46 per cow per year for the Holstein Friesian breed. Generally, the NR depends on the milk production level assumed. For the Simmental breed, depending on the scenario, the simulation results show a 54 to 200% larger average NR of investment in activity meters for estrus detection with a milk yield of 9,000 kg/yr compared with 7,000 kg/yr. For the Holstein Friesian breed, the effect of the modeled milk yield on the NR is much less pronounced. Average NR of investment in activity meters are greater for larger herd sizes because of cost degression effects. An additional equipping of heifers has, on average, a positive effect on the economics of activity meters for estrus detection because of the resulting reduction in the age at first calving. Considering all scenarios, the probability of a positive NR of investment in activity meters ranges between 74 and 98% for the Simmental breed and between 85 and 99% for the Holstein Friesian breed.

Effect of the Booroola fecundity (FecB) gene on the reproductive performance of ewes under assisted reproduction

Reproductive traits are important factors in sheep production. The Booroola fecundity (FecB) gene—the first major gene for prolificacy identified in sheep—has a positive effect on ovulation rates and litter size under natural reproductive conditions. However, the effect of the FecB gene on reproductive performance under assisted reproduction, which uses many artificial hormones, remains unclear. In the present study, we evaluated the effect of FecB (BMPR-1B mutation) on reproductive performance under assisted reproduction, and examined offspring body weight at birth and weaning and survival rate at weaning. There were no differences among three genotype groups (homozygous carrier, BB; heterozygous carrier, B+; non-carrier, ++) in terms of estrus detection rate, time to estrus onset, or estrus duration following estrus synchronization (P > 0.05). The pregnancy rates at 60 d were similar among three genotype groups after artificial insemination (P > 0.05). However, the B allele had an additive effect on litter size (one copy resulted in an increase of 0.88 lambs and two copies produced an additional 0.41 lambs; P < 0.01), and increased lambing and fecundity rates (P < 0.01). After multiple ovulation, the average numbers of recovered embryos per ewe were 9.16 ± 0.79, 8.20 ± 0.77, and 8.44 ± 0.61 in the BB, B+, and ++ ewes, respectively (P > 0.05). There were no differences in the fertilization rate or numbers of grade 1–2 embryos among different groups (P > 0.05). The birth and weaning weights of lambs from BB and B+ ewes were lower than those of lambs born from ++ ewes (P < 0.01) owing to the high fecundity. The survival rate of lambs at weaning did not differ among groups (P > 0.05). Our results indicated that the presence of the B allele had an additive effect on litter size after artificial insemination, but it did not influence the parameters of estrus synchronization and multiple ovulation. Furthermore, the higher prolificacy in ewes carrying the B allele was associated with a reduction in offspring body weight at birth and weaning.

Comparing dairy farm milk yield and components, somatic cell score, and reproductive performance among United States regions using summer to winter ratios

Heat stress abatement is a challenge for dairy producers in the United States, especially in the southern states. Thus, managing heat stress is critical to maintain dairy cow performance in the summer. The ability to employ a metric to measure heat stress and evaluate abatement strategies may benefit dairy producers by providing meaningful feedback on the effectiveness of current and future management strategies with the goal of improving heat stress management. Therefore, this study aimed to explore the use of the summer to winter performance ratio metric to quantify and compare farm performance variables among regions of the United States. Monthly performance data recorded by the Dairy Herd Improvement Association from 2007 to 2016, for all US Dairy Herd Improvement Association herds processing records through Dairy Records Management Systems (Raleigh, NC), were obtained. Season dates were based on the astronomical definition of the Northern Hemisphere with summer as June 21 to September 21 and winter as December 21 to March 19. States were grouped into regions based on climate zone classification. Performance records included a total of 16,573 herds [Northeast (n = 7,955), Midwest (n = 6,555), Northern Plains (n = 305), Southeast (n = 1,370), and Southern Plains (n = 388) regions]. Herd test day performance variables energy-corrected milk, somatic cell score, milk fat and protein percentage, conception rate, heat detection rate, and pregnancy rate in summer and winter were used to calculate summer to winter ratios for each region. The MIXED procedure of SAS 9.4 (SAS Institute Inc., Cary, NC) was used to compare test day performance variables. The effects of year, mean days in milk, mean 150-d milk, mean herd size, and number of milkings per day were included as covariates in the models. Dairy cattle performance in all climate regions was negatively affected by summer heat stress, but some regions greater than others. A difference was also observed among regions when comparing summer to winter ratios for each performance parameter. This indicates that summer performance varies by climate region identified by the summer to winter ratio and demonstrates usefulness of the metric to monitor degree of heat stress based on performance.

A novel strategy for resynchronization of ovulation in Nelore cows using injectable progesterone (P4) and P4 releasing devices to perform two timed inseminations within 22 days.

We aimed to evaluate the reproductive performance of Nelore lactating cows submitted to a resynchronization 12days after timed artificial insemination (TAI) with or without a long-acting progesterone (P4-LA) treatment. Nelore cows were submitted to a P4/oestradiol-based TAI protocol (D0=insemination). On D12, cows in the control group (n=184) received a new P4 intravaginal device (0.96g), whereas cows in the P4-LA group (n=192) received the P4 device and 75mg P4-LA. Cows identified as non-pregnant (n=120) by regression of corpus luteum using colour Doppler ultrasonography on D20 had the P4 device removed and received 500ug of sodium cloprostenol, 1mg of oestradiol cypionate and 300IU of eCG and were re-inseminated on D22. There was no difference (p>0.10) in the pregnancy rate at D20, D30 and D60 after first TAI between the control (69%, 59.7% and 57%, respectively) and P4-LA (67%, 55.7%, and 55.2%, respectively) groups. Pregnancy losses were similar between both groups (p>0.1). For cows submitted to the second TAI, the pre-ovulatory follicle size did not differ (p>0.1), but the oestrous detection and pregnancy rates were greater (p<0.05) in the P4-LA group (92.2% [59/64] and 60.9% [39/64], respectively) than in controls (75% [42/56] and 44.6% [25/56]). The cumulative pregnancy rate after two TAIs did not differ (p>0.1) between control (73.3% [135/184]) and P4-LA (76% [146/192]) groups. The use of P4-LA at 12days after TAI potentially increases the pregnancy rates for a new early resynchronization strategy associated with the Doppler imaging for pregnancy diagnosis and results in an alternative to perform two TAIs in 22days in beef cows.