Determinants of estrous behavior in lactating Holstein cows

Early prediction of oestrus for herd fertility management in cattle and buffaloes - a review

Oestrus is defined as a period when a female animal exhibits characteristic sexual behaviour in the presence of a mature male. Oestrous manifestation in dairy animals is due to the oestrogen (E2) effect on the central nervous system (CNS). It is a critical issue to be considered on a priority basis. Inefficient oestrous detection reduces the fertility status of the herd. The primary and most reliable indicator of oestrus is standing to be mounted by a bull or another female herd mate, signalling receptivity and the pre-ovulatory state in dairy cattle. Oestrous detection is primarily a management challenge requiring skill and vigilance. To improve the efficiency of oestrous detection in dairy cattle, visual observation is one of the best methods if done three times a day; however, heat detection aids, if combined, give better results. However, techniques like using teaser bulls, tail painting, chin ball markers, ultrasound (USG) examination, hormonal analysis and examination of cervicovaginal mucus (CVM) improve oestrous detection efficiency. Moreover, the changes in production systems have reduced the expression of oestrous behaviour among cows, due to higher oestrogen (E2) metabolism. Therefore, automated systems, such as pedometers, accelerometers and acoustic sensors like infrared thermography (IRT) and image processing, have significantly enhanced reproductive performance by facilitating oestrous detection and optimizing insemination schedules. From this review, we would conclude that oestrous detection alone contributes considerably to the reproductive status of the herd; therefore, applying different methods of oestrous detection reduces the incidence of missed oestrus and improves the fertility status of the herd.

Interval from Oestrus to Ovulation in Dairy Cows-A Key Factor for Insemination Time: A Review

This review describes the oestrus-to-ovulation interval, the possibility of predicting the time of ovulation, and the optimum time for insemination relative to oestrus in dairy cows. The duration of oestrus in dairy cows is approximately 8-20 h, with differences possibly related to the methods of oestrus detection and the frequency of observations. Most cows ovulate approximately 24-33 h after the onset of oestrus and 15-22 h after the end of oestrus. The interval from the preovulatory luteinising hormone (LH) surge to ovulation is approximately 4-30 h. Ovulation occurs when follicle diameter averages 18-20 mm. When it is possible to correctly determine the beginning of oestrus, artificial insemination can be performed utilizing the "a.m.-p.m. rule", and only one insemination may be applied. In cows with too long or too short oestrus-to-ovulation intervals, fertility can be compromised. One important factor that can alter the oestrus-to-ovulation interval is acute or chronic heat stress during the warm season. When there is a risk that insemination may occur too early or too late with respect to the time of ovulation, GnRH administration can be considered.

Reproduction in the era of genomics and automation

Much progress has been made in the reproductive efficiency of lactating dairy cows across the USA in the past 20years. The standardisation of evaluation of reproductive efficiency, particularly with greater focus on metrics with lesser momentum and less lag-time such as 21-day pregnancy rates (21-day PR), and the recognition that subpar reproductive efficiency negatively impacted profitability were major drivers for the changes that resulted in such progress. Once it became evident that the genetic selection of cattle for milk yield regardless of fertility traits was associated with reduced fertility, geneticists raced to identify fertility traits that could be incorporated in genetic selection programs with the hopes of improving fertility of lactating cows. Concurrently, reproductive physiologists developed ovulation synchronisation protocols such that after sequential treatment with exogenous hormones, cows could be inseminated at fixed time and without detection of oestrus and still achieve acceptable pregnancy per service. These genetic and reproductive management innovations, concurrently with improved husbandry and nutrition of periparturient cows, quickly started to move reproductive efficiency of lactating dairy cows to an upward trend that continues today. Automation has been adopted in Israel and European countries for decades, but only recently have these automated systems been more widely adopted in the USA. The selection of dairy cattle based on genetic indexes that result in positive fertility traits (e.g. daughter pregnancy rate) is positively associated with follicular growth, resumption of ovarian cycles postpartum, body condition score and insulin-like growth factor 1 concentration postpartum, and intensity of oestrus. Collectively, these positive physiological characteristics result in improved reproductive performance. Through the use of automated monitoring devices (AMD), it is possible to identify cows that resume cyclicity sooner after calving and have more intense oestrus postpartum, which are generally cows that have a more successful periparturient period. Recent experiments have demonstrated that it may be possible to adopt targeted reproductive management, utilising ovulation synchronisation protocols for cows that do not have intense oestrus postpartum and relying more heavily on insemination at AMD-detected oestrus for cows that display an intense oestrus postpartum. This strategy is likely to result in tailored hormonal therapy that will be better accepted by the public, will increase the reliance on oestrus for insemination, will improve comfort and reduce labour by reducing the number of injections cows receive in a lactation, and will allow for faster decisions about cows that should not be eligible for insemination.

Time of insemination in relation to pregnancy rates in beef cattle after oestrus detection with automated activity monitoring system

BACKGROUND

The timing of artificial insemination is critical to achieve acceptable results in cattle production systems. Over the past 60 years the length and expression of oestrus in dairy cattle has altered. Recent studies have indicated the optimal timing for insemination after the commencement of oestrus may now be earlier than traditional recommendations in beef cattle, as is the case in dairy cattle. The aim of the current study was to evaluate the effect of time from onset of oestrus [as determined by an automated activity monitoring system (AAMS)] to artificial insemination (AI) on pregnancy outcome in Norwegian beef cattle. Five commercial beef suckler herds participated in a cohort study by providing data on the time of AAMS alarm and time of AI. Blood sampling on the day of AI was performed and serum progesterone concentration measured. Pregnancy detection was performed by transrectal ultrasonography and aging of the fetus performed when necessary. A mixed logistic regression model was fitted to study the effect of time from AAMS alarm to AI on pregnancy outcome. Time categories used in the model were < 12 h, 12-24 h, and > 24 h.

RESULTS

AI periods (n = 229) with serum progesterone concentration < 1 ng/mL were available for analysis. Overall pregnancy risk per AI for the whole study period was 65.5%, with an inter-herd variation from 10 to 91%. Median time elapsed from AAMS alarm to AI was 17.75 h. Herd affected pregnancy outcome (P = 0.001), while breed and parity status (heifer/cow) did not. The time category closer to AAMS alarm 0-12 h showed a numerically lower pregnancy risk as compared to the baseline group which had AI 12-24 h after onset of oestrus.

CONCLUSION

This study found no evidence to support a change in the recommended timing of AI in beef suckler cows.

Association of activity and subsequent fertility of dairy cows after spontaneous estrus or timed artificial insemination

The objective of this observational study was to evaluate the association between increased physical activity at first artificial insemination (AI) and subsequent pregnancy per AI (P/AI) in lactating Holstein cows following spontaneous estrus or a timed AI (TAI) protocol. We also wanted to identify factors associated with the intensity of activity increase (PA) captured by automated activity monitors (AAM) and fertility. Two experiments were conducted, in which cows either were inseminated based on the alert of the AAM system (AAM cows) or received TAI following a 7-d Ovsynch protocol (TAI cows) if not inseminated within a farm-specific period after calving. Experiment 1 included 2,698 AI services from AAM cows and 1,042 AI services from TAI cows equipped with the Smarttag Neck (Nedap Livestock Management) from a dairy farm in Slovakia (farm 1). In the second experiment, 6,517 AI services from AAM cows and 1,226 AI services from TAI cows fitted with Heatime (Heatime Pro; SCR Engineers Ltd.) from 8 dairy farms in Germany (farms 2-9) were included. Pregnancy diagnosis was performed on a weekly basis by transrectal ultrasound (farms 1, 3, 7, 8) or by transrectal palpation (farms 2, 4-6, 9). Estrous intensity was represented by the peak value of the change in activity. In experiment 1, PA was categorized into low (x-factor 0-20) and high (x-factor 21-100) PA, and in experiment 2 into low (activity change = 35-89) and high (activity change = 90-100) PA. In TAI cows from both experiments, PA was additionally categorized into cows with no AAM alert. Data were analyzed separately for AAM and TAI cows using multinomial logistic regression models for PA in TAI cows and logistic regression models for PA in AAM cows and P/AI in both groups. In experiment 1, P/AI of AAM cows was greater for AI services performed with conventional frozen semen (57.6%) compared with sexed semen (47.2%), whereas type of semen only tended to be associated with P/AI in TAI cows (54.4% conventional frozen semen vs. 48.9% sexed semen). In experiment 2, P/AI was greater for fresh semen (AAM cows: 44.4% vs. TAI cows: 44.2%) compared with conventional frozen semen (AAM cows: 37.6% vs. TAI cows: 34.6%). In both experiments, pregnancy outcomes were associated with PA. In experiment 1, AAM cows with high PA (55.1%) had greater P/AI than cows with low PA (49.8%). Within TAI cows, cows with no alert (38.8%) had reduced P/AI compared with cows with low (54.2%) or high PA (61.8%). In experiment 2, AAM cows with high PA (45.8%) had greater P/AI compared with cows with low PA (36.4%). Timed AI cows with no alert (27.4%) had decreased P/AI compared with cows with low (41.1%) or high (50.8%) PA. The greatest risk factors for high PA were parity (experiment 1) and season of AI (except for TAI cows from experiment 1). We conclude that high PA at the time of AI is associated with greater odds of pregnancy for both AAM and TAI cows. In both experiments, about 2 thirds of AAM cows (experiment 1: 69.9% and experiment 2: 70.7%) reached high PA, whereas only approximately one-third or less of TAI cows (experiment 1: 37.3% and experiment 2: 23.6%) showed high PA. Although we observed similar results using 2 different AAM systems for the most part, risk factors for high PA might differ between farms and insemination type (i.e., AAM vs. TAI).

Estrus Detection in a Dairy Herd Using an Electronic Nose by Direct Sampling on the Perineal Region

Estrus detection is very important for the profitability of dairy herds. Different automatic systems for estrus detection have been developed over the last decades. Our study aimed to assess the ability of the electronic nose (EN) MENT-EGAS prototype to detect estrus, based on odor release from the perineal headspace in dairy cattle by direct sampling. The study was performed in an Italian dairy farm using 35 multiparous Holstein-Friesian cows. The cows were divided into three groups: group I included 10 lactating 5-month pregnant cows, group II included 19 lactating cycling cows, and group III included 6 cows that were artificially inseminated 18 days before the trial. Odors from the perineal headspace were collected using the MENT-EGAS prototype. In group I, odors were collected once a day for 5 consecutive days. In group II, odors were collected twice daily from day 18 until day 1 of the reproductive cycle. In group III, odors were also collected twice daily from the presumable day 18 of gestation until day 22. Principal component analyses (PCA) of the perineal headspace samples were performed. PCA in group I revealed no significant discrimination. PCA in group II revealed clear discrimination between proestrus and estrus, and between estrus and metestrus but no significant discrimination was obtained between proestrus and metestrus. PCA in group III revealed that in four cows the results were similar to group I and in two cows the results were similar to group II. On day 40 of the presumable pregnancy, the ultrasound examination revealed that only the four cows were pregnant and the other two cows were regularly cycling. On the basis of our findings, we conclude that it is possible to accurately detect estrus in dairy cattle from directly collected odor samples using the MENT-EGAS prototype. This represents the first study of estrus detection using an EN detection by direct sampling. EN technologies, such as MENT-EGAS, could be applied in the future in dairy cattle farms as a precise, non-invasive method for estrus detection.

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.

Occurrence and greater intensity of estrus in recipient lactating dairy cows improve pregnancy per embryo transfer

The aim of this study was to determine the association between occurrence and intensity of estrous expression with pregnancy success in recipient lactating dairy cows subjected to embryo transfer (ET). Two observational studies were conducted. Holstein cows were synchronized using the same timed ET protocol, based on estradiol and progesterone in both experiments. At 9 d after the end of the timed ET protocol only animals that had ovulated were implanted with a 7-d embryo [experiment 1 (Exp. 1); n = 1,401 ET events from 1,045 cows, and experiment 2 (Exp. 2); n = 1,147 ET events from 657 cows]. Embryos were produced in vivo (Exp. 1 and Exp. 2) and in vitro (only Exp. 2), then transferred to recipient cows as fresh or frozen-thawed. Pregnancy was confirmed at 29 and 58 d after the end of timed ET protocol. In Exp. 1, animals had their estrous expression monitored through a tail chalk applied on the tail head of the cows and evaluated daily for chalk removal (no estrus: 100% of chalk remaining; estrus: <50% of chalk remaining). In Exp. 2, cows were continuously monitored by a leg-mounted automated activity monitor. Estrous expression was quantified using the relative increase in physical activity at estrus in relation to the days before estrus. Estrous expression was classified as no estrus [<100% relative increase in activity (RI)], weak intensity (100-299% RI), and strong intensity (≥300% RI). Data were analyzed by analysis of variance using mixed linear regression models (GLIMMIX) in SAS (SAS Institute Inc.). A total of 65.2% (914/1,401) and 89.2% (1,019/1,142) of cows from Exp. 1 and Exp. 2, respectively, displayed estrus at the end of the ovulation synchronization protocol. In Exp. 1, cows expressing estrus before to ET had greater pregnancy per ET than those that did not [41.0 ± 2.3% (381/914) vs. 31.5 ± 2.9% (151/487), respectively]. Similarly, in Exp. 2, cows classified in the strong intensity group had greater pregnancy per ET compared with cows in the weak intensity and no estrus groups [41.3 ± 2.2% (213/571) vs. 32.7 ± 2.7% (115/353) vs. 11.3 ± 3.5% (26/218), respectively]. There was no effect of ET type on pregnancy per ET in Exp. 1. However, in Exp. 2, cows that received an in vivo-produced embryo, either fresh or frozen, had greater pregnancy per ET compared with cows that received in vitro-produced embryo. Cows receiving embryos in the early blastocyst and blastocyst stage had greater fertility compared with cows receiving embryos in the morula stage. There was an interaction between the occurrence of estrus and the stage of embryo development on pregnancy per ET, cows which displayed estrus and received a morula or early blastocyst had greater pregnancy per ET than cows that did not display estrus. In conclusion, the occurrence and the intensity of estrous expression improved pregnancy per ET in recipient lactating dairy cows and thus could be used as a tool to assist in the decision making of reproduction strategies in dairy farms.

Daily activity measures and milk yield immediately before and after a fertile estrus and during the period of expected return to estrus after insemination in dairy cows

The objective of this study was to characterize changes in milk yield and other physical measures during a 7-d periestrual period encompassing estrus (d 0) and during a 16-d period of expected return to estrus beginning at d 17 after artificial insemination (AI) until pregnancy status was determined on d 32. Lactating dairy cows milked thrice daily were fitted with CowManager SensOor ear tags (Agis) capable of assessing real-time eating, rumination, resting, high activity (estrus), ear-surface temperature, and heat alerts. Data were uploaded to the cloud, downloaded daily into Excel (Microsoft Corp.) spreadsheets, averaged to produce daily means for each activity, and analyzed as repeated measures relative to estrus or to d 17 after AI. Daily milk was unchanged during the periestrual period but was greater in nonpregnant cows that failed to return to estrus (NP-NR) during d 21 through 26 compared with NP cows that returned to estrus (NP-R) and pregnant (PREG) cows during that same period. Daily ear-surface temperature was greater during d 1 to 3 compared with d 0 and averaged 0.6 to 1.7°C greater from d 17 through 32 in NP-NR cows compared with NP-R and PREG cows. Daily rumination and resting times reached nadirs on d 0, with decreases occurring 48 h before estrus. Both rumination and resting times increased by 25 or 81% on the day after estrus, respectively. Rumination and resting times were less in NP-R cows during d 22 through 26 compared with NP-NR and PREG cows. In contrast, daily eating time was greatest on the day of estrus compared with 3 d before and after estrus. The NP-R cows spent more time eating during d 17 through 32 compared with NP-NR and PREG cows. High activity increased by 97% during 48 h before estrus, peaked at estrus, and decreased to a constant level during d 1 through 3. The NP-R cows had greater high activity on d 22 through 26 compared with NP-NR and PREG cows. We conclude that resting and rumination activity decreased to daily nadirs, whereas eating and high activity peaked on the day of estrus. Fertile estrus was associated with 12% greater high activity, 11% less resting time, and 6% less rumination time. In addition, cows that returned to estrus after AI had greater daily eating and high activity times and less rumination and resting time during the period of expected return to estrus after AI compared with pregnant cows and cows failing to return to estrus.

Review: Perspective on high-performing dairy cows and herds

Milk and dairy products provide highly sustainable concentrations of essential amino acids and other required nutrients for humans; however, amount of milk currently produced per dairy cow globally is inadequate to meet future needs. Higher performing dairy cows and herds produce more milk with less environmental impact per kg than lower performing cows and herds. In 2018, 15.4% of the world's dairy cows produced 45.4% of the world's dairy cow milk, reflecting the global contribution of high-performing cows and herds. In high-performing herds, genomic evaluations are utilized for multiple trait selection, welfare is monitored by remote sensing, rations are formulated at micronutrient levels, health care is focused on prevention and reproduction is managed with precision. Higher performing herds require more inputs and generate more waste products per cow, thus innovations in environmental management on such farms are essential for lowering environmental impacts. Our focus is to provide perspectives on technologies and practices that contribute most to sustainable production of milk from high-performing dairy cows and herds.

Resynchronizing the first eligible estrus in dairy cattle after a prior insemination and fertility of the prior insemination after gonadotropin-releasing hormone and progesterone treatments

The hypothesis of this study tested whether application of designed treatments to synchronize estrus in nonpregnant previously inseminated lactating dairy cows increased the proportion of nonpregnant cows in estrus before early pregnancy diagnosis on Day 32 after the previous insemination (Day 0) and increase fertility of the pretreatment insemination. A progesterone insert (CIDR) and GnRH were applied to cows after insemination to resynchronize the returning estrus of cows that failed to conceive on Day 0. The combination of GnRH (Day 14) and a CIDR insert (d 17 through 24) in experiment 1 (n = 347 cows) did not increase (P = 0.13) the proportion of nonpregnant cows returning to estrus before pregnancy diagnosis, but increased (P < 0.01) the synchrony of their return by 24.4% points, and delayed (P < 0.01) that return by 2.3 ± 0.3 d compared with controls. Ovulation risk after GnRH treatment on Day 14 was only 10%. For cows that failed to return to estrus before Day 32, progesterone concentration on Days 14 and 17 were less than that in cows that returned to estrus by Day 32 and in pregnant cows. Cows that returned to estrus had larger follicles and fewer numbers of CL on Day 21 than pregnant cows and cows that failed to return to estrus, but concentrations of pregnancy-associated glycoproteins on Day 28 indicated that cows failing to return to estrus were likely pregnant but suffered embryo death. In experiment 2 (n = 881), use of GnRH alone (Day 7), a CIDR insert alone (Days 14 through 21), or in combination, failed to increase the proportion of nonpregnant cows in estrus before pregnancy diagnosis on Day 32 compared with controls. Cows receiving the CIDR insert had increased (P < 0.01) synchrony of estrus by 24-34% points compared with cows that did not receive a CIDR insert. More cows receiving GnRH had 2 or more CL on Days 14 and 21 compared with controls. Ovulation risk after GnRH on Day 7 was greater than 66%. In both experiments combined, treatments with GnRH or GnRH + CIDR insert increased (P = 0.015) pretreatment pregnancy per AI by 7.1% points, but did not affect pregnancy loss. Although administering GnRH with or without a CIDR insert synchronized returns to estrus, treatments failed to increase the proportion of nonpregnant cows reinseminated before pregnancy diagnosis, but increased pretreatment pregnancy risk.

Invited review: A 2020 perspective on pasture-based dairy systems and products

Grazing pasture is the basis for dairy production systems in regions with temperate climates, such as in Ireland, New Zealand, parts of Australia, the United States, and Europe. Milk and dairy products from cows on pasture-based farms predominantly consuming fresh grazed grass (typically classified as "grass-fed" milk) have been previously shown to possess a different nutrient profile, with potential nutritional benefits, compared with conventional milk derived from total mixed ration. Moreover, pasture-based production systems are considered more environmentally and animal welfare friendly by consumers. As such, there is significant potential for market capitalization on grass-fed dairy products. As competition in this space increases, the regulations of what constitutes as grass-fed vary between different regions of the world. With this in mind, there is a need for clear and independently accredited grass-fed standards, defining the grass-fed criteria for labeling of products as such, subsequently increasing the clarity and confidence for the consumer. This review outlines the numerous effects of pasture production systems on dairy product composition, nutritional profile, and sustainability, and highlights potential future methods for authentication.

Factors associated with estrous expression and subsequent fertility in lactating dairy cows using automated activity monitoring

The objective of this observational study was to identify factors associated with estrous duration (DU) and intensity measured as the peak of activity (PA) change and subsequent fertility in lactating Holstein cows using a neck-mounted automated activity monitor (Heatime Pro, SCR Engineers Ltd., Netanya, Israel). Ambient temperature and relative humidity were recorded hourly to calculate the temperature-humidity index (THI). A total of 5,933 estrus events from 3,132 cows located on 8 commercial dairy farms in Germany were used for this study. Farms participated in monthly DHIA testing. Pregnancy diagnosis was performed either by transrectal palpation [farm 1: 42 ± 3 d; farm 3: 40 ± 3 d; farms 4 and 8: 38 ± 3 d; farm 5: 43 ± 3 d after artificial insemination (AI)] or transrectal ultrasonography (farms 2, 6, and 7: 30 ± 3 d after AI). Estrous intensity was categorized based on peak activity of estrus into low (35-89 index value), and high (90-100 index value) PA. Overall, 73.5% of estrus events were of high PA. The mean (± standard error of the mean) DU was 14.94 ± 0.06 h. There was a strong correlation between DU and PA (r = 0.67). In the final statistical model, only PA was associated with pregnancy per artificial insemination (P/AI), with 1.35 greater odds of pregnancy for cows with high PA compared with cows with low PA. Increased THI 1 wk before AI was associated with shorter DU, lower PA, and decreased P/AI. A small percentage of cows (4.7%) showed short interestrus intervals (i.e., more than 1 activity peak within 7 d close to the event of estrus), resulting in reduced DU, PA, and P/AI. The change of weighted rumination was associated with DU and PA, as a lower nadir was associated with a greater risk for high PA and long DU. There was no association, however, between the nadir of change of weighted rumination and P/AI. Whereas milk yield and somatic cell count from the DHIA test date before AI were negatively associated with estrous expression, neither milk yield nor somatic cell count was associated with P/AI. Surprisingly, multiparous cows expressed estrus with longer DU (13.15 ± 0.31 h) compared with primiparous cows (12.52 ± 0.32 h), whereas PA did not differ among parities. Pregnancy per AI was greater for primiparous (29.4%) than for multiparous (22.1%) cows. An estrus event with long DU or high PA was more likely later in lactation. Milk fat, milk protein, milk urea nitrogen, and lactose from the DHIA test date closest to AI had no association with estrous expression or P/AI. In conclusion, DU and PA were highly correlated, and cows with high PA were particularly associated with greater odds for pregnancy. A negative association between estrous expression and P/AI was identified for increased THI 1 wk before AI and cows with short interestrus intervals using automated activity monitor.

Timing of artificial insemination using fresh or frozen semen after automated activity monitoring of estrus in lactating dairy cows

The objective of this observational experiment was to determine the association between the time of artificial insemination (AI) and pregnancy per AI (P/AI) in lactating Holstein cows inseminated with either fresh or frozen semen considering different characteristics of an estrus event (i.e., onset, peak, and end) using an automated activity monitoring system. A total of 3,607 AI services based on the alert of an automated activity monitoring system (Heatime; SCR Engineers Ltd., Netanya, Israel) were evaluated from 4 commercial dairy farms in Germany. Pregnancy diagnosis was performed by transrectal palpation 38 ± 3 d after AI or by transrectal ultrasonography 30 ± 3 d after AI. Estrus intensity was categorized based on peak activity of estrus (PAE) into low (35-89 index value) and high (90-100 index value) intensity. The mean (± standard deviation) duration of an estrus event was 14.3 ± 4.6 h. The mean (± standard deviation) interval from onset of estrus (OE; moment where index value was ≥35) to AI was 16.8 ± 8.0 h, from PAE to AI was 11.9 ± 8.1 h, and from end of estrus (EE; moment where index value returned to <35) to AI was 2.5 ± 8.7 h. Primiparous cows had greater P/AI than multiparous cows, whereas first AI postpartum yielded greater P/AI compared with subsequent AI services. Type of semen was not associated with P/AI. Cows with heat stress 1 wk before AI had decreased P/AI. Cows with low estrus intensity (26.0%) were less fertile compared with cows showing high estrus intensity (32.8%). Cows with intermediate 100-d milk yield had decreased P/AI compared with cows with either low or high 100-d milk yield. There was a quadratic effect of the interval from OE to AI on P/AI. At 38 d after AI, P/AI was greatest for cows inseminated from 7 to 24 h after OE, within 18 h after PAE, or from 5 h before EE to 12 h after EE. There was no interaction between the interval from OE to AI and type of semen. There tended to be an interaction between the intervals from PAE to AI and type of semen and from EE to AI and type of semen. Cows inseminated with fresh semen within 5 h before EE had greater P/AI compared with frozen semen, whereas cows inseminated with frozen semen from 13 to 18 h after EE had greater P/AI compared with fresh semen. In conclusion, inseminating cows from 7 to 24 h after OE or 1 to 18 h after PAE yielded greatest P/AI irrespective of type of semen. In addition, high estrus intensity was positively associated with P/AI.

Associations between genomic merit for daughter pregnancy rate of Holstein cows and metabolites postpartum and estrus characteristics

Genetic selection of Holstein cattle in the past 2 decades has seen an increased attention to fertility traits. Our hypotheses were that genomic merit for daughter pregnancy rate (GDPR) is positively associated with metabolic responses, hazard of estrus, and estrus characteristics. Pregnant heifers (n = 821) from one herd that were genotyped within 2 mo of birth (Clarifide, Zoetis, Parsippany, NJ) were fitted with automated monitoring devices (SCR Inc., Netanya, Israel) -21 ± 14 d relative to calving. Estrus characteristics recorded from calving to 62 d postpartum were evaluated. Blood samples were collected weekly from a subsample (n = 499) of cows, from 7 to 28 d postpartum, for determination of insulin-like growth factor-1, glucose, and nonesterified fatty acids. Cows received artificial insemination or embryo transfer following detected estrus and those not detected in estrus were submitted to an ovulation synchronization protocol starting at 75 d in milk. Linear and quadratic associations between GDPR and outcomes were analyzed, but when appropriate, results are presented according to GDPR quartile (Q1 = -1.8 to 0.8; Q2 = 0.9 to 1.7; Q3 = 1.8 to 2.5; Q4 = 2.6 to 5.9) based on the parameter estimates of the multivariable models. Genomic merit for daughter pregnancy rate was positively associated with insulin-like growth factor-1 (Q1 = 24.3 ± 0.2; Q2 = 26.8 ± 0.2; Q3 = 28.2 ± 0.2; Q4 = 30.6 ± 0.3 ng/mL) and glucose (Q1 = 67.0 ± 0.1; Q2 = 69.1 ± 0.2; Q3 = 69.6 ± 0.2; Q4 = 70.8 ± 0.2 mg/dL) concentrations, but GDPR was negatively associated with nonesterified fatty acid concentration (Q1 = 281.2 ± 4.9; Q2 = 262.0 ± 5.9; Q3 = 239.3 ± 5.0; Q4 = 221.6 ± 4.7 μmol/L). A positive association was observed between GDPR and hazard of estrus [adjusted hazard ratio and 95% confidence interval = 1.16 (1.06, 1.28)] and number of estrus events (Q1 = 0.50 ± 0.03; Q2 = 0.62 ± 0.04; Q3 = 0.74 ± 0.05; Q4 = 0.86 ± 0.06) within 62 d postpartum, duration of estrus (Q1 = 14.10 ± 0.04; Q2 = 14.48 ± 0.04; Q3 = 14.67 ± 0.04; Q4 = 14.98 ± 0.04 h), probability of activity peak (0 = no estrus, 100 = maximum activity) ≥86 (Q1 = 0.80 ± 0.03; Q2 = 0.83 ± 0.02; Q3 = 0.83 ± 0.03; Q4 = 0.85 ± 0.2), and probability of heat index ≥86 (Q1 = 0.77 ± 0.04; Q2 = 0.81 ± 0.05; Q3 = 0.83 ± 0.03; Q4 = 0.86 ± 0.03). Conversely, GDPR was negatively associated with rumination nadir at estrus (Q1 = -35.5 ± 0.1; Q2 = -37.0 ± 0.1; Q3 = -38.0 ± 0.1; Q4 = -39.6 ± 0.1 min). We detected a positive association between GDPR and hazard of pregnancy (adjusted hazard ratio = 1.11, 95% confidence interval = 1.03, 1.19). Selection for GDPR may improve the hormonal and metabolic status of cows postpartum, leading to earlier resumption of cyclicity, and may improve detection of estrus in commercial herds because it was positively associated with estrus characteristics.

Understanding the trade-off between the environment and fertility in cows and ewes

The environment contributes to production diseases that in turn badly affect cow performance, fertility and culling. Oestrus intensity is lower in lame cows, and in all cows 26% potential oestrus events are not expressed (to avoid getting pregnant). To understand these trade-offs, we need to know how animals react to their environment and how the environment influences hypothalamus-pituitary-adrenal axis (HPA) interactions with the hypothalamus-pituitary-ovarian axis (HPO). Neurotransmitters control secretion of GnRH into hypophyseal portal blood. GnRH/LH pulse amplitude and frequency drive oestradiol production, culminating in oestrus behaviour and a precisely-timed GnRH/LH surge, all of which are disrupted by poor environments. Responses to peripheral neuronal agents give clues about mechanisms, but do these drugs alter perception of stimuli, or suppress consequent responses? In vitro studies confirm some neuronal interactions between the HPA and HPO; and immuno-histochemistry clarifies the location and sequence of inter-neurone activity within the brain. In both species, exogenous corticoids, ACTH and/or CRH act at the pituitary (reduce LH release by GnRH), and hypothalamus (lower GnRH pulse frequency and delay surge release). This requires inter-neurones as GnRH cells do not have receptors for HPA compounds. There are two (simultaneous, therefore fail-safe?) pathways for CRH suppression of GnRH release via CRH-Receptors: one being the regulation of kisspeptin/dynorphin and other cell types in the hypothalamus, and the other being the direct contact between CRH and GnRH cell terminals in the median eminence. When we domesticate animals, we must provide the best possible environment otherwise animals trade-off with lower production, less intense oestrus behaviour, and impaired fertility. Avoiding life-time peri-parturient problems by managing persistent lactations in cows may be a worthy trade-off on both welfare and economic terms – better than the camouflage use of drugs/hormones/feed additives/intricate technologies? In the long term, getting animals and environment in a more harmonious balance is the ultimate strategy.

Economic Viability of Adoption of Automated Oestrus Detection Technologies on Dairy Farms: A Review

Simple Summary

The accurate and timely detection of oestrus is a central element of good dairy herd management as it ultimately determines the level of milk production and is core to the economic viability of the farm business. However, the traditional method of oestrus detection, which occurs by observing the dairy cows standing immobile while being mounted, is usually time-consuming, repetitive and requires considerable skill and experience on the part of the farmer to attain a reasonable level of efficiency. Given the limitation of the traditional method of oestrus detection, a number of automated oestrus detection (AOD) technologies have been developed. However, the rate of adoption of these technologies remains low. One reason that has been proposed for farmers’ low adoption of such technologies has been their lack of knowledge around the potential economic returns from investing in AOD technologies. In this paper, we review the empirical literature on the viability of investment in AOD technologies from an economic perspective. The conclusion of this study provides evidence from which farmers can make more informed decisions in relation to investing in AOD technologies. The review and analysis is also of importance for informing policy, as it provides an examination of the incentives and levers that could improve productivity on dairy farms.

Abstract

The decision for dairy farmers to invest in automated oestrus detection (AOD) technologies involves the weighing up of the costs and benefits of implementation. In this paper, through a review of the existing literature, we examine the impacts of investment in AOD technologies in relation to the profitability and technical performance of dairy farms. Peer-reviewed articles published between 1970 and 2019 on the investment viability of AOD technologies were collated and analysed. We capture the different measures used in assessing the economic performance of investment in AOD technologies over time which include net present value (NPV), milk production, Benefit-Cost Ratio (BCR), internal rate of return (IRR) and payback period (PBP). The study concludes that investment in AOD technologies is not only worthwhile but also contributes to farm profitability.

Effect of estrous detection strategy on pregnancy outcomes of lactating Holstein cows receiving artificial insemination and embryo transfer

Objectives of the current experiment were to evaluate the effects on reproductive performance of adding an automated estrous detection (AED) device to the reproductive management of Holstein cows. In addition, we aimed to determine whether the AED device would equally influence the reproductive performance of cows receiving artificial insemination and those receiving embryo transfer. Cows (n = 1,244) were observed daily for estrous detection by trained farm personnel with the aid of a tail head mounting device. Cows (n = 641) enrolled in the AED treatment were fitted with a neck-mounted automated estrus detection device, and cows enrolled in the control (CTRL, n = 603) treatment were not fitted with the AED device. Cows not detected in estrus by 54 ± 3 DIM received 1 injection of PGF_2α, and those not detected in estrus by 68 ± 3 DIM were enrolled in an ovulation synchronization protocol. The hazard of first service tended to be affected by treatment [CTRL: referent, AED: adjusted hazard ratio (AHR) = 1.11, 95% confidence interval (CI) = 0.98, 1.25], and we determined a tendency for the AED treatment to reduce the proportion of cows receiving the first service at fixed time (39.7 ± 5.7 vs. 45.5 ± 5.8%). After the first service, high-producing cows enrolled in the AED treatment were more likely to be pregnant (19.1 ± 2.4 vs. 31.8 ± 3.0%), but no differences between the AED and CTRL treatments were observed among low-producing cows (24.9 ± 2.9 vs. 24.7 ± 2.9%). The hazard of second service was affected by treatment (CTRL: referent, AED: AHR = 1.22, 95% CI = 1.01, 1.47), and the AED treatment reduced the proportion of cows receiving the second service at fixed time compared with the CTRL treatment (15.7 ± 2.2 vs. 21.9 ± 2.5%). After the second service, the AED treatment tended to increase the proportion of cows pregnant (31.0 ± 3.0 vs. 24.9 ± 2.6%) and tended to reduce the proportion of cows that lost pregnancy between the first and second pregnancy exams (9.7 ± 3.3 vs. 16.7 ± 4.6%). The interaction between treatment and type of service did not affect percentage of cows pregnant and pregnancy loss to the first and second services. The hazard of pregnancy was affected by the interaction between treatment and milk yield, in that cows with above the median milk yield in the AED treatment became pregnant at a faster rate than CTRL cows, but no difference between treatments was observed among cows with milk yield below the median. Cows with above the median milk yield had shorter duration of estrus and were less likely to have activity peak at estrus ≥89 (0 = minimum, 100 = maximum). The current experiment suggests that AED devices may improve reproductive performance not only by increasing service rates but also by improving accuracy of estrous detection. According to the current experiment, high-producing cows may benefit most from the addition of AED devices to reproductive management.

The Influence of Different Types of Outdoor Access on Dairy Cattle Behavior

Pasture access for dairy cows is highly valued both by cows and the public at large. When pasture access is not feasible, farmers can provide cows with alternative forms of outdoor access, such as an outdoor bedded pack, that may be easier to implement on some farms. We reviewed the literature on how lying, standing, walking, feeding, social, and estrus behaviors are influenced by pasture and other types of outdoor areas. Pasture allows the expression of grazing and can facilitate the expression of lying, standing, walking, and estrus behaviors. In addition, pasture can decrease the number of negative social interactions between cows, likely because more space per cow is provided than what is normally available indoors. The provision of soft flooring and an open space in outdoor bedded packs appears to provide some benefits for lying, standing, and walking behavior and may also have positive effects on social behavior, especially with larger space allowances. The effects of an outdoor bedded pack on estrus behavior are less well-documented, but the provision of a standing surface that provides better footing than typically available indoors may promote estrus behavior. Alternative outdoor areas assessed to date appear to be less attractive for cows than pasture, perhaps because these areas do not provide the opportunity to graze. We encourage future research to investigate the importance of grazing for dairy cows. The motivation of dairy cows to access alternative outdoor areas should also be investigated. As cow preference for the outdoors depends on many factors, providing cows a choice may be of particular importance.

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 (PGF_2α, 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 PGF_2α, 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 PGF_2α to induce estrus. Cows not AIE within 7 d were enrolled in Resynch (GnRH, 7 d later PGF_2α, 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 PGF_2α 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.

Estrous characteristics and reproductive outcomes of Holstein heifers treated with 2 prostaglandin formulations and detected in estrus by an automated estrous detection or mounting device

Dinoprost tromethamine (DIN), a molecule similar to endogenous PGF_2α, has a half-life of approximately 9 min. Cloprostenol sodium (CLO), a synthetic analog of PGF_2α, has a half-life of approximately 3 h. We hypothesized that treatment of Holstein heifers with CLO would improve estrous detection rate, estrous characteristics, service rate, and overall reproductive performance compared with DIN. Currently in the United States, heifers are largely inseminated based on signs of estrus, which is detected visually or with the aid of mounting detection devices (MD). Automated estrous detection devices (AED) are becoming more accessible to producers, but it is not clear whether they present advantages in the reproductive management of heifers. Therefore, we hypothesized that the use of an AED would improve service and pregnancy rates compared with detection of estrus with the aid of a MD. Holstein heifers (n = 1,019) were enrolled in the experiment at 10 to 11 mo of age, when they were fitted with a Heatime HR LD System (SCR Ltd., Netanya, Israel). At 12 mo of age, we paired heifers according to estrous cycle phase and randomly assigned them to treatments in a 2 × 2 design: PGF_2α formulation (CLO vs. DIN) and estrous detection treatment (AED vs. MD). Heifers in the AED treatment were detected in estrus only by the Heatime HR LD System, whereas heifers in the MD treatment were detected in estrus only by the Kamar Heatmount Detector (Kamar Products Inc., Zionsville, IN). Treatments with the same PGF_2α formulations were repeated 14 d after the first treatment if heifers had not been detected in estrus. A sub-group of heifers had blood sampled on the day of PGF_2α treatment and within 24 h of onset of estrus to determine progesterone and estradiol concentrations. Treatment with CLO reduced the progesterone concentration within 24 h of onset of estrus compared with DIN (0.04 ± 0.01 vs. 0.11 ± 0.01 ng/mL). Among heifers in mid diestrus on the day of PGF_2α treatment, CLO reduced the interval to estrus compared with DIN (72.0 ± 2.2 vs. 82.4 ± 2.4 h). Prostaglandin F_2α formulation and estrous detection treatment did not affect pregnancy to the first service. The interval between the first and second services tended to be reduced for the AED treatment compared with the MD treatment (24.4 ± 0.5 vs. 25.7 ± 0.6 d). Prostaglandin F_2α formulation and estrous detection treatment did not affect the hazard of pregnancy. Although CLO treatment may shorten the interval to estrus in heifers at mid diestrus compared with DIN, PGF_2α formulation did not affect reproductive performance. In the current experiment, no advantages in reproductive performance were observed when estrous detection was based on an AED compared with a MD.

The Dairy Cattle Housing Dilemma: Natural Behavior Versus Animal Care

Animal welfare has historically been defined at the intersection of 3 key concepts: (1) health and biological functioning, (2) affective state, and (3) natural living. For farmed animals, such as dairy cattle, health and biological functioning are often prioritized, sometimes at the expense of natural living. In this work, the authors discuss the perceived conflict between the duty of care exercised by producers and the resulting consequences to natural behavior expression. They also provide considerations on how indoor housing systems for dairy cattle may be refined to better permit natural behaviors, with particular emphasis on animals' motivational priorities.

Change of daily milk yield during estrous period in Holstein cattle raised under Mediterranean climate

This study was conducted to determine the effect of estrus on the daily milk yield in Holstein cows and to investigate the chance of using the possible milk yield changes in determining the estrus. During the 3-year period of the study, 103 dairy cows were observed 4 days before and 4 days after daily milk yield of 240 estruses and a total of 2174 daily milk yields were evaluated. Variance analysis was used to determine the factors affecting the daily milk yield, and the LSD test was used for multiple comparisons. Insemination year, insemination season, number of lactation, milk yield group, and daily milk yield of lactation period were found to be significant (P < 0.01). On the other hand, the effect of estrus days on milk yield was insignificant. In the days of estrus, the least square mean of milk yield is 31.0 kg, while the lowest and highest milk yields are 10.2 kg and 62.9 kg. The daily milk yield in the estruses decreased by an average of 300 g, which decreased to 400 g by continuing 1 day after the estruses. The next day, however, it increased rapidly by 600 g, and then dropped again, probably due to the effect of metestrus. It was found that, among all estruses, 31.3% of cows decreased their milk yield, whereas 26.5% of cows increased their milk yield. However, 42.2% of cows both decreased and increased their milk yield in different estruses. The interval between birth and the first insemination after were found to be longer (97.5 days and 92.9 days) at high milk-yielding cows compared to the low milk-yielding cows. According to the results of this study, daily milk yield changes could not be used as an estrus indicator.

A 100-Year Review: Practical female reproductive management

Basic knowledge of mechanisms controlling reproductive processes in mammals was limited in the early 20th century. Discoveries of physiologic processes and mechanisms made early in the last century laid the foundation to develop technologies and programs used today to manage and control reproduction in dairy cattle. Beyond advances made in understanding of gonadotropic support and control of ovarian and uterine functions in basic reproductive biology, advancements made in artificial insemination (AI) and genetics facilitated rapid genetic progress of economically important traits in dairy cattle. Technologies associated with management have each contributed to the evolution of reproductive management, including (1) hormones to induce estrus and ovulation to facilitate AI programs; (2) pregnancy diagnosis via ultrasonography or by measuring conceptus-derived pregnancy-associated glycoproteins; (3) estrus-detection aids first devised for monitoring only physical activity but that now also quantitate feeding, resting, and rumination times, and ear temperature; (4) sex-sorted semen; (5) computers and computerized record software packages; (6) handheld devices for tracking cow location and retrieving cow records; and (7) genomics for increasing genetic progress of reproductive and other economically important traits. Because of genetic progress in milk yield and component traits, the dairy population in the United States has been stable since the mid 1990s, with approximately 9 to 9.5 million cows. Therefore, many of these technologies and changes in management have been developed in the face of increasing herd size (4-fold since 1990), and changes from pastoral or dry-lot dairies to increased housing of cows in confinement buildings with freestalls and feed-line lockups. Management of groups of "like" cows has become equally important as management of the one. Management teams, including owner-managers, herdsmen, AI representatives, milkers, and numerous consultants dealing with health, feeding, and facilities, became essential to develop working protocols, monitor training and day-to-day chores, and evaluate current trends and revenues. Good management teams inspect and follow through with what is routinely expected of workers. As herd size will undoubtedly increase in the future, practical reproductive management must evolve to adapt to the new technologies that may find more herds being milked robotically and applying technologies not yet conceived or introduced.

Automated oestrus detection using multimetric behaviour recognition in seasonal-calving dairy cattle on pasture

AIM To evaluate the performance of a novel accelerometer-based oestrus detection system (ODS) for dairy cows on pasture, in comparison with measurement of concentrations of progesterone in milk, ultrasonographic examination of ovaries and farmer observations. METHODS Mixed-breed lactating dairy cows (n=109) in a commercial, seasonal-calving herd managed at pasture under typical farming conditions in Ireland, were fitted with oestrus detection collars 3 weeks prior to mating start date. The ODS performed multimetric analysis of eight different motion patterns to generate oestrus alerts. Data were collected during the artificial insemination period of 66 days, commencing on 16 April 2015. Transrectal ultrasonographic examinations of the reproductive tract and measurements of concentrations of progesterone in milk were used to confirm oestrus events. Visual observations by the farmer and the number of theoretically expected oestrus events were used to evaluate the number of false negative ODS alerts. The percentage of eligible cows that were detected in oestrus at least once (and were confirmed true positives) was calculated for the first 21, 42 and 63 days of the insemination period. RESULTS During the insemination period, the ODS generated 194 oestrus alerts and 140 (72.2%) were confirmed as true positives. Six confirmed oestrus events recognised by the farmer did not generate ODS alerts. The positive predictive value of the ODS was 72.2 (95% CI=65.3-78.4)%. To account for oestrus events not identified by the ODS or the farmer, four theoretical missed oestrus events were added to the false negatives. Estimated sensitivity of the automated ODS was 93.3 (95% CI=88.1-96.8)%. The proportion of eligible cows that were detected in oestrus during the first 21 days of the insemination period was 92/106 (86.8%), and during the first 42 and 63 days of the insemination period was 103/106 (97.2%) and 105/106 (99.1%), respectively. CONCLUSIONS and CLINICAL RELEVANCE The ODS under investigation was suitable for oestrus detection in dairy cows on pasture and showed a high sensitivity of oestrus detection. Multimetric analysis of behavioural data seems to be the superior approach to developing and improving ODS for dairy cows on pasture. Due to a high proportion of false positive alerts, its use as a stand-alone system for oestrus detection cannot be recommended. As it is the first time the system was investigated, testing on other farms would be necessary for further validation.

Invited review: Learning from the future-A vision for dairy farms and cows in 2067

The world's population will reach 10.4 billion in 2067, with 81% residing in Africa or Asia. Arable land available for food production will decrease to 0.15 ha per person. Temperature will increase in tropical and temperate zones, especially in the Northern Hemisphere, and this will push growing seasons and dairy farming away from arid areas and into more northern latitudes. Dairy consumption will increase because it provides essential nutrients more efficiently than many other agricultural systems. Dairy farming will become modernized in developing countries and milk production per cow will increase, doubling in countries with advanced dairying systems. Profitability of dairy farms will be the key to their sustainability. Genetic improvements will include emphasis on the coding genome and associated noncoding epigenome of cattle, and on microbiomes of dairy cattle and farmsteads. Farm sizes will increase and there will be greater lateral integration of housing and management of dairy cattle of different ages and production stages. Integrated sensors, robotics, and automation will replace much of the manual labor on farms. Managing the epigenome and microbiome will become part of routine herd management. Innovations in dairy facilities will improve the health of cows and permit expression of natural behaviors. Herds will be viewed as superorganisms, and studies of herds as observational units will lead to improvements in productivity, health, and well-being of dairy cattle, and improve the agroecology and sustainability of dairy farms. Dairy farmers in 2067 will meet the world's needs for essential nutrients by adopting technologies and practices that provide improved cow health and longevity, profitable dairy farms, and sustainable agriculture.

A review of oestrous behaviour and detection in dairy cows

A number of measurable physiological events characteristically occur and cause changes during the perioestrual period including the classical, diagnostic sign of standing behaviour. The onset of oestrus coincides with peak titres of oestradiol-17β that subsequently induce the preovulatory surge of LH within 1 to 3 h and ovulation of a mature follicle some 24 to 32 h after the onset of oestrus. Although detection efficiencies are consistently greater in higher producing herds, oestrus-detection efficiency generally has declined in recent years as herd size and milk production have increased. New technologies have introduced some needed assistance for detecting cows in oestrus. These include various in expensive heat mount detectors to more sophisticated electronic gadgetry, such aspedometry and radiotelemetric sensors that detect temperature, tissue impedance, and pressure. Oestrus detection aids are usually more efficient but not necessarily more accurate than visual observation. Differences in housing and environmental conditions, in addition to labor inputs, costs, and efficacies, result in variable acceptance of such technologies. Detection efficiency and accuracy can be improved by simultaneous use of synergistic technologies; those that compliment each other and monitor different indicators of oestrus. Combining technologies for simultaneous measurements of several physiological events associated specifically with the onset of oestrus and their radiotelemetrically signaling to a central computer for subsequent analysis should provide greater efficiency ofoestrus detection with fewer false positives. The ultimate goal of determining the onset of oestrus or ovulation is to predict the optimal timing for insemination. Ultimately, herd personnel must interpret information gathered by these technologies and judge whether or not and when to inseminate cows based on their visual inspection of identified cows.

Effect of floor type on the performance, physiological and behavioural responses of finishing beef steers

BACKGROUND

The study objective was to investigate the effect of bare concrete slats (Control), two types of mats [(Easyfix mats (mat 1) and Irish Custom Extruder mats (mat 2)] fitted on top of concrete slats, and wood-chip to simulate deep bedding (wood-chip placed on top of a plastic membrane overlying the concrete slats) on performance, physiological and behavioral responses of finishing beef steers. One-hundred and forty-four finishing steers (503 kg; standard deviation 51.8 kg) were randomly assigned according to their breed (124 Continental cross and 20 Holstein-Friesian) and body weight to one of four treatments for 148 days. All steers were subjected to the same weighing, blood sampling (jugular venipuncture), dirt and hoof scoring pre study (day 0) and on days 23, 45, 65, 86, 107, 128 and 148 of the study. Cameras were fitted over each pen for 72 h recording over five periods and subsequent 10 min sampling scans were analysed.

RESULTS

Live weight gain and carcass characteristics were similar among treatments. The number of lesions on the hooves of the animals was greater (P < 0.05) on mats 1 and 2 and wood-chip treatments compared with the animals on the slats. Dirt scores were similar for the mat and slat treatments while the wood-chip treatment had greater dirt scores. Animals housed on either slats or wood-chip had similar lying times. The percent of animals lying was greater for animals housed on mat 1 and mat 2 compared with those housed on concrete slats and wood chips. Physiological variables showed no significant difference among treatments.

CONCLUSIONS

In this exploratory study, the performance or welfare of steers was not adversely affected by slats, differing mat types or wood-chip as underfoot material.

Behavioral and hormonal pattern of repeat breeder cows around estrus

Repeat breeder (RB) cows were compared with normal (CTRL) ones with respect to behavioral estrus intensity, endocrine patterns and concentrations of plasma estradiol, progesterone and LH around estrus, and ovulation timing. A total of 27 and 31 cycles in 12 RB and 18 CTRL cows, respectively, were synchronized by means of the Ovsynch protocol followed by a single PG injection after 7 days. Behavioral estrus and ovulation were observed in 81.5 and 83.8% of the synchronized cycles in the RB and CTRL cows respectively. The RB and CTRL groups had similar estrus durations of 21.4 and 19.6 h respectively, but estrus was more intense in the RB, as indicated by numerically higher overall activity indexes and higher peak neck activity. The interval from PG injection to estrus onset (considered as proestrus) was 8.2 h shorter in RB than in CTRL cows, at 47.9 and 56.1 h respectively (P<0.007), but the average preovulatory follicle size was similar. The estradiol concentration at peak was numerically higher (21%) and the AUC tended to be higher in the RB cows than in the CTRL cows. LH secretion during the period from 18 to 3 h before the LH peak was also lower in RB than in CTRL cows: 2.5 and 4.6 ng/ml respectively (P<0.01). In conclusion, the behavioral estrus was more intense in the RB cows; nevertheless, short proestrus and subdued LH concentrations before the LH peak, which could impair oocyte competence and development, were first reported in RB cows.

Expression and detection of estrus in dairy cows: the role of new technologies

Despite the widespread adoption of hormonal synchronization protocols that allow for timed artificial insemination (AI), detection of estrus plays an important role in the reproductive management program on most dairies in the United States. Increased physical activity is a secondary sign of estrus in dairy cattle, and a new generation of electronic systems that continuously monitor physical activity to predict timing of AI have been developed and marketed to the dairy industry. A variety of management and physiologic challenges inhibit detection of behavioral estrus on farms, but the prevalence of anouvular cows near the end of the voluntary waiting period is particularly problematic. Only 70% of lactating Holstein cows were detected in estrus when using an activity monitoring system, with the remaining 20% of cows classified as anovular and 10% ovulating without showing signs of activity. Mean time of AI in relation to ovulation based on the activity monitoring system was acceptable for most of the cows with increased activity, however, variability in the duration of estrus and timing of AI in relation to ovulation could result in poor pregnancy outcomes in some cows. Use of a Presynch-Ovsynch protocol for submission of cows for first AI has been widely adopted by dairies in the United States, and a combined approach in which AI based on activity is followed by submission of cows not detected with activity to timed AI after synchronization of ovulation may be an effective strategy for submission of cows to first AI. Based on a field trial on a large commercial dairy in the United States, the activity monitoring system detected 70% of cows with increased activity after the second PGF2α injection of a Presynch-Ovsynch protocol, however, cows inseminated to increased activity had fewer pregnancies per AI (P/AI) compared with cows with increased activity after the second PGF2α injection that received timed AI after completing the Presynch-Ovsynch protocol. Based on an economic model comparing reproductive management programs with varying levels of AI to estrus v. timed AI, the rate of estrus detection and the P/AI to inseminations based on AI to detected estrus v. timed AI affected the decision to inseminate based on activity v. timed AI. In conclusion, an activity monitoring system detected increased activity in about 70% of lactating Holstein cows on a large commercial dairy in the United States, however, synchronization of ovulation and timed AI was beneficial to inseminate cows not detected with increased activity by the activity monitoring system.

Profiles of ovarian steroids, luteinizing hormone and estrous signs from luteolysis to ovulation in lactating and non-lactating dairy cows

The aims of the present study were to investigate the profiles of ovarian steroids and luteinizing hormone (LH) and the appearance of estrous signs in relation to luteolysis and ovulation in lactating and non-lactating cows and to examine the influence of lactation on those observations. Five lactating (daily milk yield of 28.4 ± 3.2 kg; mean ± SD) and five non-lactating cycling Holstein cows were examined. Their ovaries were monitored by ultrasonography daily during one estrous cycle. Blood samples were collected daily and then at 3-h intervals after luteolysis until ovulation. Estrous signs in terms of behavior, the vulva and the vagina were checked at 8-h intervals after luteolysis until ovulation. Profiles of progesterone, estradiol-17β and LH did not differ between the groups. There were no differences in the interval from luteolysis to ovulation (4.6 ± 0.5 and 4.2 ± 0.8 days) and the interval from the estradiol-17β peak to ovulation (34.2 ± 4.5 and 30.6 ± 3.9 h) between lactating and non-lactating cows. The interval from the peak of the LH surge to ovulation was 27 h in all cows examined. Appearance of estrous signs did not differ between the groups. The vaginal estrous signs were observed conspicuously in all cows examined, but the behavioral signs were not observed in 20.0% of the cows. The duration of behavioral signs (41.3 ± 23.6 h) was shorter (P<0.05) than that of the vagina (68.9 ± 25.4 h). These results imply that lactation might not interfere with the hormonal profiles from luteolysis to ovulation.

Dairy cows continuously-housed in tie-stalls failed to manifest activity changes during estrus

Felton, C. A., Colazo, M. G., Ponce-Barajas, P., Bench, C. J. and Ambrose, D. J. 2012. Dairy cows continuously-housed in tie-stalls failed to manifest activity changes during estrus. Can. J. Anim. Sci. 92: 189–196. While pedometers are effective for estrus detection in free-stall herds, their efficacy in tie-stalls is not established. The objectives were to determine if pedometers equipped with a behavior tag for monitoring lying activity (AfiMilk Pedometer Plus Tag system) can accurately record cow activity, and if they can facilitate estrus detection in dairy cows continuously housed in tie-stalls. Nineteen lactating Holstein cows were subjected to estrus induction with prostaglandin F2α, and 18 pregnant cows served as controls. Activity was monitored for 10 d using pedometers and 24-h video recording. Pedometer and video records were compared for 6 d surrounding estrus; stepping (rc=0.85; P<0.01), lying time (rc=0.94; P<0.01), and lying bouts (rc=0.89; P<0.01) were highly correlated. Progesterone concentrations confirmed that 17 of the 19 cows responded to estrus induction; 16 of those 17 cows ovulated. Changes in mean daily activity did not differ (P>0.05) between estrus-induced cows and controls, or in the estrus-induced cows in the 48 to 72 h preceding the day of ovulation. In conclusion, while the pedometers accurately recorded cow activity in lactating cows housed in tie-stalls, they could not facilitate estrus detection because cow activity did not significantly change during estrus.

Bio-economic model to evaluate twinning rate using sexed embryo transfer in dairy herds

A stochastic bio-economic model has been used to determine the effects of new reproductive technologies over a 15-year period. A strategy of using conventional artificial insemination (AI) or embryo transfer (ET) using two sex-controlled embryos at different conception rates (CRs) and herd sizes resulted in a 24 state model. The genetic means of AI population increased over the years, and the genetic means of milk production for all of the embryo strategies were greater than those of AI. In addition, the genetic means of milk yield using different embryo-based scenarios in the expanding herds were greater than those for the fixed herds. The net profit of using sexed ET in the expanding herds was greater (P < 0.05) than that of fixed size herds. In general, there was a roughly consistent trend in net profit per cow for sexed ET strategies in the expanding herds over the years, but there was an increasing trend in net profit per cow for sexed ET strategies in the fixed herds over the years. Medium to high CRs for ET and the use of sex-controlled embryo systems, especially for induction of twin births to produce dairy replacements, will be critical elements of a system that produces significant numbers of female calves. The greater number of female calves produced in the sex-controlled scenarios allows the farmer to select animals with the best genetic potential as dairy replacement heifers; therefore, the rate of genetic gain increased in the dairy herd. Results of sensitivity analyses showed that a significant decrease in the production costs and increase in the ET performance are essential for embryo-based technologies to be profitable.