Losses In Cattle Research Articles

PENANGANAN KASUS PENCURIAN HEWAN TERNAK SAPI DI SP1 KABUPATEN SORONG OLEH POLRES AIMAS

The phenomenon of cattle theft in SP1 is increasingly disturbing the community, especially cattle breeders, because cattle breeders often experience the loss of their livestock which they suspect has been stolen by someone else. The research location is SP1 Sorong Regency. The research location is a location where cases of cattle loss often occur. Research is expected to obtain the information that researchers expect. The issue raised is about the reasons why the heirs are reluctant to receive the share they should receive. And at the Darul Falah Jekulo Kudus Islamic Boarding School to obtain information in the form of the opinion of the Kiyai or Pondok Caretaker regarding the issues raised.

Prevalence and risk factors for hair loss in outdoor-wintered beef cattle under cold weather conditions

Keeping cattle outdoors year-around is considered an attractive alternative to indoor winter-housing, due to lower investment costs and better welfare. However, hair loss, attributed to lice, may impair cattle's thermal balance during harsh winters. During the winters of 2019–2021, outdoor cattle in Sweden were studied for the prevalence and development of hair loss, while surveys were conducted among the farmers on their perceptions and attitudes around hair loss. Of the 463 groups of cattle from 75 farms enrolled in a welfare control program issued by the Swedish Board of Agriculture, 25.7% (n = 119) had at least one animal with hair loss. When we followed up a subset of animals (n = 3673) which did not receive prophylactic delousing, 15.7% developed hair loss. Hair loss occurrence increased between visits within each winter in these animals, suggesting a contagious etiology. Logistic regression analyses, using the information collected in the control program and the hair loss outcome, showed that preventive delousing before November was effective, alongside keeping animals clean and the group size small. Meanwhile, being older (>2 years) and having access to bedding materials was shown to increase the risk at an animal-level. Some groups (n = 34) had no hair loss despite receiving no prophylactic delousing. Based on the survey conducted among the farmers (n = 15), groups with lower hair loss prevalence belonged to farmers who were more observant of hair loss and gave prompt treatment. This study provides knowledge useful to limit delousing interventions without compromising animal welfare.

The effect of genetic defects on pregnancy loss in Swedish dairy cattle

The effect of carrier status of 10 lethal recessive genetic defects on pregnancy maintenance in Swedish dairy cattle was examined. The genetic defects were Ayrshire Haplotype 1, Ayrshire Haplotype 2, BTA12, BTA23, and Brown Swiss Haplotype 2 in Red Dairy Cattle (RDC), and Holstein Haplotype 1, 3, 4, 6, and 7 (HH1-HH7) in Holstein. Effects of carrier status of BTA12 and HH3 on conception rate (CR), interval from first to last service (FLS), and milk production were also examined. Data were obtained for 1,429 herds in the Swedish milk recording system, while information on carrier status of genetic defects was obtained from the Nordic Cattle Genetic Evaluation. In total, data on 158,795 inseminations in 28,432 RDC and 22,018 Holstein females were available. Data permitted separate analyses of BTA12 and HH3, but carrier frequencies of other defects were too low to enable further analysis. Pregnancy loss was defined as failure to maintain pregnancy, where pregnancy status was confirmed with manual and chemical pregnancy diagnosis, insemination, calving, sales and culling data. Odds ratios (OR) and probabilities of pregnancy loss and CR were estimated using generalized linear mixed models, while pregnancy loss, CR, FLS, milk, protein, and fat yields were analyzed using linear mixed models. Pregnancy losses were reported on average within the first month post-AI. At-risk matings were more prone to suffer pregnancy loss in BTA12 (OR = 1.79) and HH3 carriers (OR = 1.77) than not-at-risk matings. At-risk matings also had lower CR (OR = 0.62 and 0.63 for BTA12 and HH3, respectively) than not-at-risk matings. Carrier females of BTA12 had longer FLS and higher milk production than noncarriers. Conception rate and pregnancy maintenance could be improved by avoiding at-risk matings. This finding could help reduce pregnancy loss due to genetic defects in the breeding program for improved fertility.

Evolution and Impact of Agrarian and Revenue Systems: A Study of Hyderabad State

This article based on the ‘evolution and impact of agrarian and revenue systems: A study of Hyderabad state’ during the second half of the 19th century important changes have taken place in the agricultural sector. The new land revenue reforms and the land tenure systems introduced by Salar Jung contributed to the growth of agriculture cultivation and the introduction of modern methods of cultivation increased the yields. Importantly, the state of Hyderabad was on Economic depression and unfavorable trade due to impact I world war struck the state economy. However, the area under cultivation in 18 percent at the end of the period against 1911. The disappointed rainfall resulted in restricted cultivation for the period 1921-31. Consequence was cattle loss and people migration. Part of the Telangana declared as famine-stricken and relief rendered. The state experienced good health of its economy during the period 1901-1911. During the period, irrigation and railway expansion and increase in textile and mine industry. Agricultural methods were improved and area cultivated advanced (84 per cent increased from 1881 figure). It resulted in increase in population (36 per cent). In 1911-1921, the natural calamity, plague (1911) and influenza epidemic (1918-19) were the main setbacks. Hyderabad State evolved from the Mughal Provinces of the Deccan under NizamalMulkAsalJah. The Mughal agrarian system as existing in the Deccan was continued and adopted by NizamelMulk and it formed the basis for that of Hyderabad. The same was continued by Nizam Ali Khan and his successors with some changes and improvement from time to time to the exigencies of time and for the benefit and welfare of the people. The study may be classified into three systems as followed Land Revenue System, Jagirdari System and the Chauth and Sardeshmukhi System.

Genetic Evaluation of Bovine Papillomavirus Types Associated with Teat Papillomatosis in Polish Dairy Cattle with the Report of a New Putative Type.

Teat papillomatosis is reported to be one of the factors causing mastitis and milk losses in dairy cattle. Little is known about bovine papillomavirus (BPV) circulation in the European cattle population, and no reports can yet be found about its prevalence in Polish herds. In this study, 177 BPV-like lesions were collected from teats of 109 slaughtered cows. BPV was identified in 39 of the examined animals, using PCR amplification and Sanger dideoxy sequencing. In total, 10 BPV types were isolated, among which the most common were infections caused by types 8 and 7. Macroscopically, "rice-grain" type lesions dominated (76%) and were mainly found on one teat (57.4%). The diversity of BPV types causing teat papillomatosis in Polish cows seems to be large, with nine already known types isolated and a new putative type found. The spread of new types among the worldwide cattle population can be seen for the first time, as type 25 and so called isolates BPV42 and BPV43 were found in the European cattle population.

Genomic-enhanced breeding values for heat stress tolerance in Girolando cattle in Brazil

Heat stress is a major challenge for dairy herds and can lead to significant production reduction, mainly in tropical climate. Differences in decreased milk production in animals is associated with genetic variation. The overall goal was to investigate the effect of heat stress in milk yield of Girolando cattle in tropical climate and to identify the most appropriate statistical approach for evaluation and selection for heat tolerance in different breed compositions of Girolando. Therefore, to quantify heat stress effects on milk yield loss in Girolando cattle, random regression models were applied on test-day milk yield records (TDMY) and weather data. In addition, different statistical models were evaluated for estimating variance components and predicting breeding values for heat stress (HS). The data comprised 648,072 TDMY of 69,431 first-lactation Girolando cows of different breed compositions, and 21,147 genotyped animals, with daily temperature and humidity measurements from weather stations closest to the tested herds, between 2000 and 2020. We used daily mean values of temperature-humidity index (THI) for the day of test and the 3 previous days as the measure of HS. Heat stress thresholds estimated for the different breed compositions of Girolando in this study were THI 80 for 1/4H, 1/2H and 5/8H; THI 78 for 3/4H animals and THI 77 for 7/8H animals. Average milk production can decrease by up to 34% due to heat stress. Estimated average heritability for TDMY regressed to the THI was 0.21, while the heritability estimated for TDMY regressed to the DIM was 0.29. A correlation of 0.55 was observed between the GEBVs of HS tolerance and GEBV milk yield. The parameters estimated in this study indicate that genomic selection for heat tolerance in dairy cattle is a step towards ensuring valuable tropical production efficiency and improving animal welfare in the face of predicted increases in heat stress events and increase tropical production efficiency.

First Molecular Detection of Neospora caninum in Feces of Grey Wolf (Canis lupus) and Golden Jackal (Canis aureus) Populations in Slovenia.

Neospora caninum is an obligate intracellular parasite that causes reproductive disorders and major economic losses in cattle, and induces neuromuscular disorders in canids. Exogenous infections are becoming increasingly important due to disease outbreaks. The sylvatic life cycle of N. caninum interferes with the domestic dog-ruminant life cycle, but understanding of it is scarce. The population of wild canids may play an important role in parasite dispersion. Feces from 42 grey wolves (Canis lupus) and 39 golden jackals (Canis aureus) were analyzed for the N. caninum Nc5 gene using a novel real-time PCR (qPCR) with a detection limit of 5 targets/µL in clinical samples. Three wolves (3/42; 7.1%) and one golden jackal (1/39; 2.6%) tested positive, which is the first detection of N. caninum in the population of grey wolves in Slovenia and the first detection of N. caninum DNA in the feces of a golden jackal. In addition to the grey wolf, we propose the golden jackal as a potential definitive host with hypothetical epidemiological importance for the sylvatic-domestic life cycle of N. caninum, due to its proximity to human habitats and its rapid expansion throughout Europe.

Heat Stress Mitigation Strategies in Feedyards: Use, Perceptions, and Experiences of Industry Stakeholders.

The purpose of this study was to: (1) understand heat mitigation strategies currently used and recommended by feedyard operators, veterinarians, and nutritionists, (2) understand their perceptions of heat mitigation strategies related to cattle health, performance, welfare, and carcass quality, (3) quantify the frequency of extreme heat events, and (4) understand industry needs associated with heat stress mitigation strategies. An online survey was shared via 11 industry association listservs. Descriptive statistics were performed on 56 responses (n = 22 operators, 26 veterinarians and eight nutritionists). Thematic analysis was performed on free-response questions. Sixteen (72.7%) operators, 23 (88.5%) veterinarians and eight (100%) nutritionists utilized at least one heat mitigation strategy. "Changing processing and shipping hours" (n = 42, 75%) had the most "strongly agree" responses when asked about strategy effectiveness. The majority of respondents agreed that heat stress negatively impacts cattle health, performance, and welfare (Mean ± SD; ≥7.8 ± 2.6 for all roles). Forty-two (75%) respondents experienced cattle death loss from extreme heat events. Thematic analysis indicated that respondents perceived pen infrastructure and water/feed management as important considerations for better mitigating heat stress impacts. When asked what resources would be helpful, respondents indicated research and data regarding the effectiveness of various strategies.

Loss of organic cattle to the conventional value chains in Ireland: what are the economic and environmental impacts?

PurposeThis paper aims to quantify the loss (or leakage) of organic cattle to conventional value chains in Ireland and assess its economic and environmental impacts.Design/methodology/approachThe paper adopts a Bio-economy Input-Output (BIO) model, a quantitative economic model representing the interdependencies between different sectors of the economy, to assess the economic and environmental impacts of organic leakage in the Irish beef sector.FindingsThe study reveals that 17% of organic cattle aged under 1 year old leave the organic value chain, leaking to the conventional market as a result of imbalances in the development of the beef value chain. The economic cost of this organic leakage is 5.66 million euros. Leakage also has environmental effects because of changes in lifecycle methane and nitrogen emissions based on longer finishing times on organic farms and chemical fertilisers applied on conventional farms. The organic leakage results in a reduction of 82 tons of methane emission and 52 additional tons of nitrogen emission, which leads to 11,484 tons of net global warming potential (GWP) for a 100-year time horizon.Research limitations/implicationsBecause of data availability, the research focussed on the baseline year 2015, which had national data available for disaggregation in Ireland. Therefore, researchers are encouraged to assess the economic and environmental impacts when more recent data are available and to analyse the change in the impacts over the years.Practical implicationsThis study contributes to the discussion on organic conversion and provides valuable insights for stakeholders, especially policymakers, for the design of future organic schemes.Originality/valueThis is the first paper to assess organic leakage in the beef sector.

Neospora caninum infection in dairy cattle in Egypt: a serosurvey and associated risk factors

Neospora caninum (N. caninum) is one of the causative agents that causing cattle abortion, and severe economic losses. Due to the scarcity of data on N. caninum infection in Egyptian cattle, the purpose of this study was to estimate the seroprevalence and determine the risk factors for parasite infection. In four governorates in northern Egypt, 540 blood samples from cattle were taken, and tested using a commercial ELISA kit. The overall seroprevalence of N. caninum in examined cattle was 28.89%. A multivariate logistic regression model determined that age (OR = 2.63, P < 0.001), manual milking (OR = 1.39, P = 0.14), abortion history (OR = 2.78, P < 0.0001), repetition of estrus (OR = 2.31, P < 0.0001), and contact with dogs (OR = 2.57, P < 0.0001) were significant risk factors. The findings proved that N. caninum infection was one of the factors contributing to abortion and financial losses in dairy cattle in Egypt. Therefore, the application of sanitary security and control programs is very important in dairy farms.

A review of thermal stress in cattle.

Cattle control body temperature in a narrow range over varying climatic conditions. Endogenous body heat is generated by metabolism, digestion and activity. Radiation is the primary external source of heat transfer into the body of cattle. Cattle homeothermy uses behavioural and physiological controls to manage radiation, convection, conduction, and evaporative exchange of heat between the body and the environment, noting that evaporative mechanisms almost exclusively transfer body heat to the environment. Cattle control radiation by shade seeking (hot) and shelter (cold) and by huddling or standing further apart, noting there are intrinsic breed and age differences in radiative transfer potential. The temperature gradient between the skin and the external environment and wind speed (convection) determines heat transfer by these means. Cattle control these mechanisms by managing blood flow to the periphery (physiology), by shelter-seeking and standing/lying activity in the short term (behaviourally) and by modifying their coats and adjusting their metabolic rates in the longer term (acclimatisation). Evaporative heat loss in cattle is primarily from sweating, with some respiratory contribution, and is the primary mechanism for dissipating excess heat when environmental temperatures exceed skin temperature (~36°C). Cattle tend to be better adapted to cooler rather than hotter external conditions, with Bos indicus breeds more adapted to hotter conditions than Bos taurus. Management can minimise the risk of thermal stress by ensuring appropriate breeds of suitably acclimatised cattle, at appropriate stocking densities, fed appropriate diets (and water), and with access to suitable shelter and ventilation are better suited to their expected farm environment.

Dose- and time-dependent effects of interferon tau on bovine endometrial gene expression

Failure by the developing conceptus to secrete sufficient interferon tau (IFNT), required for maternal recognition of pregnancy (MRP), at the appropriate time is related to early pregnancy loss in cattle. We aimed to test the hypothesis that there is a dose- and time-dependent relationship between IFNT and the endometrial expression of key interferon-stimulated genes (ISGs) involved in the signalling cascade leading to MRP in cattle. Candidate genes were identified first through a bioinformatic approach, where integrated transcriptomic data from two previous studies were analyzed to identify endometrial genes induced by IFNT. Next, expression of selected candidate genes was investigated in vitro in endometrial explants. Endometrial explants collected from cows (n = 8) in the late luteal phase of the estrous cycle were cultured in medium without (control) or with recombinant ovine IFNT (1, 10, 100 ng/mL) for 6 h. Simultaneously, endometrial explants were cultured in medium containing 100 ng/mL IFNT for different time periods (15 min, 30 min, 1 h, 3 h, 6 h). Gene expression was analyzed by RT-qPCR. We identified 54 endometrial genes responding to IFNT and to some degree to the conceptus, from which five ISGs (CMPK2, BPNT1, IFI35, TNFSF10 and TRIM38) were further selected for the dose- and time-dependent experiments. Classical ISGs (ISG15, OAS1, MX1 and MX2) were up-regulated (P < 0.05) in endometrium by 1 ng/mL IFNT. However, other selected ISGs (CMPK2, BPNT1, IFI35, TNFSF10 and TRIM38) were induced only by higher concentrations (10 and 100 ng/mL) of IFNT (P < 0.05). In terms of duration of exposure, IFNT at 100 ng/mL induced a significant (P < 0.05) increase in ISG15 and CMPK2 expression after 1 h incubation, while all other studied ISGs in the endometrium were upregulated when cultured for 3 or 6 h, but did not affect expression when the duration of culture was for 1 h or less. These results suggest that IFNT acts on the uterus in both a dose- and time-dependent manner in cattle and that timely exposure of the endometrium to sufficient IFNT is essential for appropriate signalling to ensure successful pregnancy establishment.

Effects of subclinical Theileria orientalis Ikeda genotype infection on average daily gain ratios and a satisfactory rating in the breeding soundness exam in bull test stations in Virginia

Theileria orientalis Ikeda genotype is a tick borne hemoprotozo­an that typically causes economic losses in dairy and beef cattle in Australia, New Zealand and Japan. Acute clinical infections from T. orientalis Ikeda include anemia, icterus, ill-thrift and death. The acute phase of the infection has been associated with decreased libido in dairy bulls, decreased live weight gain in beef bulls and increased mortality in naïve adults and calves. A sequela to acute infections within a herd is persistent sub­clinical infections, which have been associated with decreased mean daily gain in suckling beef calves. In late 2017, T. orienta­lis Ikeda was detected in beef cattle from multiple counties in Virginia and was associated with anemia, weakness, late term abortions and death. As of 2022, T. orientalis Ikeda has been identified in beef cattle in 31 of 95 Virginia counties. Beef pro­duction, typically in naturally bred cow-calf operations, is the second largest agricultural commodity in Virginia. Central bull testing programs for performance evaluation and marketing of beef bulls has existed for over 60 years in Virginia. T. orienta­lis Ikeda was first detected at the Southwest bull test station in 2020 when screened at conclusion of the test. The objective of this study was to determine if subclinical infection with T. ori­entalis Ikeda affected the average daily gain (ADG) ratios of all bulls on test and the achievement of a satisfactory rating of the breeding soundness exam (BSE) for senior bulls.

An economic evaluation of cattle tick acaricide-resistances and the financial losses in subtropical dairy farms of Ecuador: A farm system approach.

Estimates of economic losses in cattle due to tick infestations in subtropical areas are limited, such as in Ecuador. Ticks affect animal production and health, but those direct effects are difficult to estimate since financial exercises carried out in farms consider both costs of the inputs and revenues. This study aims to quantify the costs of inputs involved in milk production and to know the role of acaricide treatment in the production costs on dairy farms in subtropical zones using a farming system approach. Regression and classification trees were used to study the relationship between tick control, acaricide resistance and the presence of high level of tick infestation in the farm system. Even though there was no significant direct association between high levels of tick infestation and the presence of acaricide resistance in ticks, a more complex structure for resistances operates in the manifestation of high tick infestation involving levels of farm technology and no acaricide resistance. Farms with higher levels of technology allocate a lower percentage of sanitary expenses to control ticks (13.41%) in comparison to semi-technified (23.97%) and non-technified farms (32.49%). Likewise, more technified and bigger herds have a lower annual expenditure on acaricide treatment (1.30% of the production budget equivalent to 8.46 USD per animal) compared to non-technified farms where it can represent more than 2.74% of the production budget and where the absence of cypermethrin resistance increases the treatment cost to 19.50 USS per animal annually. These results can motivate the development of information campaigns and control programmes targeted to the reality of small and medium farms that are the most affected in terms of the money they invest in controlling ticks.

Determination of Microinsurance Premiums in Cattle Farms Based on Protein Content Index and Milk Production Using the Black-Scholes Method

Micro insurance is an insurance product that is intended for low-income people with features and administration that are simple, easy to obtain, economical prices and immediate settlement of compensation. Cattle business insurance is an effort to protect breeders in event of a risk of death and loss of cattle, this insurance product is a protection against worries the burden of a large premium. This study aims to calculate the premium price using the Black-Scholes method. In this study, a correlation analysis was conducted to determine the influence the protein content on cow’s milk production. Then, modelling the protein content using ARIMA-GARCH and determining the premium using the Black-Scholes method. The results showed that the protein content of milk in cow’s milk production has a positive correlation. Protein content follows the ARIMA(1,0,0)-GARCH(1) model. Based on the results of the analysis it can be concluded that the bigger protein content in milk, the higher premium that needs to paid.

Diagnostic performance of faecal and tissue multiplex qPCR IS900/F57 for the detection of Mycobacterium avium subspecies paratuberculosis in cattle

Mycobacterium avium subspecies paratuberculosis (MAP) is responsible for bovine-paratuberculosis (bPTB), which causes high production losses in cattle. A cross-sectional study was conducted in 228 cattle to evaluate the validity and diagnostic utility of a multiplex real-time PCR (qPCR) on faecal and intestinal samples [ileocaecal valve (ICV) and ileocaecal lymph nodes (ICLN)], using intestinal tissue culture as a reference test.Based on the sensitivity, specificity, and likelihood ratios (LR) obtained, the diagnostic value of faecal qPCR for confirming MAP infection was moderate (sensitivity 50.3%, specificity 93.5%, positive LR 7.8), and low to rule it out (negative LR 0.5). In areas with a prevalence of >23% the credibility of positive results was higher than 70%. In the case of negative results, their credibility was higher than 90% in herds with an infection rate below 19%, so faecal qPCR would be very useful in these areas to certify the absence of infection. For post-mortem diagnosis, qPCR on ICV samples showed good diagnostic accuracy to confirm the disease (sensitivity 71.7%, specificity 93.3%, positive LR 10.8), with a credibility higher than 70% in animals from areas or herds with a prevalence of infection greater than or equal to 18%. The best strategy to rule out the disease was the parallel combination of both tissues (ICV + ICLN) (sensitivity 81.3%, specificity 89.5%, negative LR 0.2) with a credibility of over 95% in animals from areas with an infection prevalence of 0–20%. Faecal and tissues qPCR techniques can be used to monitor bPTB, the interpretation of results, according to epidemiological situation of the herd or area, are shown.

Biological activity of recombinant bovine IFN-α and inhibitory effect on BVDV in vitro

Type I interferon has great broad-spectrum antiviral ability and immunomodulatory function, and its receptors are expressed in almost all types of cells. Bovine viral diarrhea virus (BVDV) is an important pathogen causing significant economic losses in cattle. In this study, a recombinant expression plasmid carrying bovine interferon-α(BoIFN-α)gene was constructed and transformed into E. coli BL21 (DE3) competent cells. SDS-PAGE and Westernblotting analysis showed that the recombinant BoIFN-α protein (rBoIFN-α) was successfully expressed. It is about 36KD and exists in the form of inclusion body. When denatured, purified and renatured rBoIFN-α protein stimulated MDBK cells, the expression of interferon stimulating genes (ISGs) such as ISG15, OAS1, IFIT1, Mx1 and IFITM1 were significantly up-regulated, and reached the peak at 12 h (P< 0.001). MDBK cells were infected with BVDV with moi of 0.1 and 1.0, respectively. The virus proliferation was observed after pretreatment with rBoIFN-α protein and post-infection treatment. The results showed that the denatured, purified and renatured BoIFN-α protein had good biological activity and could inhibit the replication of BVDV in MDBK cells in vitro, which provided a basis for BoIFN-α as an antiviral drug, immune enhancer and clinical application of BVDV.

Perspective: Can early embryonic losses be reduced in lactating dairy cows?

Perspective: Can early embryonic losses be reduced in lactating dairy cows?

Review: Maintenance of the ruminant corpus luteum during pregnancy: interferon-tau and beyond.

This manuscript reviews the mechanisms that maintain the corpus luteum (CL) of pregnancy in ruminants. In mammals, ovulation and luteinization of the remaining cells in the CL are due to a surge in Luteinizing Hormone (LH). In cattle, continued secretion of pulses of LH is essential for full development and function of the CL during the estrous cycle (LH pulses), however, the few studies on the CL after d20 of pregnancy do not indicate that LH is essential for maintaining the CL of pregnancy. The first essential step in maintaining the CL of pregnancy in ruminants is overcoming the mechanisms that cause regression of the CL in non-pregnant ruminants (d18-25 in cattle; d13-21 in sheep). These mechanisms have a uterine component involving oxytocin-induced prostaglandin F2α (PGF2A) pulses and a luteal component involving decreased progesterone production and luteal cell death. There is a critical role for embryonic interferon-tau (IFNT) in suppressing the uterine secretion of PGF2A during early pregnancy (d13-21 in sheep; d16-25 in cattle) and preventing luteolysis. There are also effects of IFNT on the expression of interferon-stimulated genes in other tissues including the CL but the physiologic role of these interferon-stimulated genes is not yet clear. After the IFNT period, there is another mechanism that maintains the CL of pregnancy in ruminants since embryonic IFNT is inhibited as attachment occurs and trophoblastic binucleate/giant cells begin secretion of pregnancy-associated glycoproteins. The second mechanism for luteal maintenance has not yet been defined but acts in a local manner (ipsilateral to pregnancy), and remains functional from d25 until just before parturition. The most likely mechanisms mediating later maintenance of the CL of pregnancy are increased uterine blood flow or decreased prostaglandin transporter expression in the utero-ovarian vasculature, preventing PGF2A reaching the CL. Finally, implications of these ideas on pregnancy loss in cattle are explored, highlighting the importance of inappropriate regression of the CL of pregnancy as a mechanism for pregnancy loss in cattle.

155 Effect of lactation number on pregnancy losses in dairy cattle

155 Effect of lactation number on pregnancy losses in dairy cattle