Is the Modern High Potential Dairy Cow Suitable for Organic Farming Conditions?

It is not acceptable to compromise animal welfare in any system of farming. Feeding should be aimed at meeting the nutritional requirements at the various stages of production. This paper deals with the detrimental effects that organic, extensive or low input farming systems may have on the energy status in early lactation of the high potential dairy cow. Bovine ketosis is the most important disease resulting from insufficient energy intake in early lactation. It is also important to realize that ketosis is a part of the so-called periparturient disease complex, which includes milk fever, mastitis, retained placenta, endometritis and poor fertility also. All these diseases are interrelated and reflect to a large extent the nutritional status of the animal. If organic dairy farming is to be successful the breeding programmes have to divert from selection for high yields as a main goal, to more emphasis on a flatter lactation curve, less production diseases and longevity.     

Plasma Vitamin E and Blood Selenium Concentrations in Norwegian Dairy Cows: Regional Differences and Relations to Feeding and Health

Plasma α-tocopherol (vit E) and blood selenium (Se) concentrations in February were determined in samples from 314 dairy cows in Norway, selected to provide a representative subset of the Norwegian dairy cow population. Each sample was followed by a questionnaire with information about feeding of the cow at the time of sampling. The results were correlated to herd data and to calving and health data for each cow from the Norwegian Dairy Herd Recording System and the Norwegian Cattle Health Recording System. The mean concentrations were 6.9 μg vit E per ml plasma and 0.16 μg Se per g blood. Both levels were highest in mid lactation. Plasma vit E varied with the amount of silage fed to the cow, while blood Se varied with the amount of concentrates and mineral supplements, and with geographical region. No differences in vit E or Se levels were found between cows with recorded treatments for mastitis, parturient paresis or reproductive disorders in the lactation during or immediately prior to sampling, and those without such treatments. For ketosis, a small difference in blood Se was found between the groups with or without recorded treatments. It is concluded that winter-fed lactating cows in Norway had an adequate plasma level of vit E and a marginal-to-adequate level of Se.     

Association between body energy content in the dry period and post-calving production disease status in dairy cattle

The transition from gestation to lactation is marked by significant physiological changes for the individual cow such that disease incidence is highest in early lactation. Around the time of calving, cows rely on mobilisation of body energy reserves to fill the energy deficit created by an increase in nutrient demands at a time of restricted feed intake. It is well established that monitoring of body energy reserves in lactation is an important component of herd health management. However, despite their influence on future health and productivity, monitoring of body energy reserves in the dry period is often sparse. Further, there is increasing concern that current dry off management is inappropriate for modern cattle and may influence future disease risk. This study aimed to identify candidate indicators of early lactation production disease from body energy data collected in the dry period and production data recorded at the time of dry off. Retrospective analysis was performed on 482 cow-lactations collected from a long-term Holstein-Friesian genetic and management systems project, the Langhill herd in Scotland. Cow-lactations were assigned to one of four health groups based on health status in the first 30 days of lactation. These four groups were as follows: healthy, reproductive tract disorders (retained placenta and metritis), subclinical mastitis and metabolic disorders (ketosis, hypocalcaemia, hypomagnesaemia and left displaced abomasum). ANOVA, employing a GLM was used to determine effects for the candidate indicator traits. Cows which were diagnosed with a reproductive tract disorder in the first 30 days of lactation experienced a significantly greater loss in body energy content, body condition score and weight in the preceding dry period than healthy cows. The rate of change in body energy content during the first 15 days of the dry period was −18.26 MJ/day for cows which developed reproductive tract disorder compared with +0.63 MJ/day for healthy cows. Cows diagnosed with subclinical mastitis in the first 30 days of lactation had significantly greater milk yield at dry off in the previous lactation than cows that developed a reproductive tract disorder or metabolic disease in addition to a significantly higher yield to body energy content ratio at dry off than healthy cows. Physiological and production traits recorded in the lactation and dry period preceding a disease event differed between cows which developed different diseases post-calving. Differences in these traits allow the development of new disease indicators for use in models for the prediction of disease risk in the transition period.     

Estimation of Mineral and Trace Element Profile in Bubaline Milk Affected with Subclinical Mastitis

The milk samples from buffaloes of Murrah breed at mid lactation stage, reared at an organised dairy farm, were screened for subclinical mastitis based on bacteriological examination and somatic cell count following International Dairy Federation criteria. Milk samples from subclinical mastitis infected and healthy buffaloes were analysed to evaluate physicochemical alterations in terms of protein, fat, pH, electrical conductivity, chloride, minerals (sodium, potassium and calcium) and trace elements (iron, zinc, copper and selenium). In the present study, protein, fat, zinc, iron, calcium and selenium content was significantly lower (P < 0.001), while pH and electrical conductivity were significantly higher in mastitic milk as compared to normal milk. Concentration of electrolytes mainly sodium and chloride significantly increased with higher somatic cell count in mastitic milk and to maintain osmolality; potassium levels decreased proportionately. Correlation matrix revealed significantly positive interdependences of somatic cell count with pH, electrical conductivity, sodium and chloride. However, protein, fat, calcium and potassium were correlated negatively with elevated somatic cell count in mastitic milk. It is concluded that udder infections resulting in elevated somatic cells may alter the mineral and trace element profile of milk, and magnitude of changes may have diagnostic and prognostic value.     

Transition Diseases in Grazing Dairy Cows Are Related to Serum Cholesterol and Other Analytes

The objectives of this study were to describe the incidence of postpartum disease and to evaluate the association with serum cholesterol concentrations during the first 3 weeks after calving in grazing dairy cows. The association between non-esterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), calcium and postpartum diseases was also evaluated. A total of 307 Holstein dairy cows from 6 commercial grazing herds in Osorno, Chile, were monitored from calving until 21 days in milk. Cases of retained placenta, clinical hypocalcemia and clinical mastitis were recorded by the farmer using established definitions. Twice weekly, cows were evaluated for metritis by the same veterinarian based on vaginal discharge and body temperature. Postpartum blood samples were collected weekly and analyzed for serum concentrations of cholesterol, NEFA, BHBA and calcium. Cows were considered as having subclinical ketosis if BHBA >1.2 mmol/L, and subclinical hypocalcemia if calcium <2.0 mmol/L in any of the 3 weekly samples. Overall, 56% of the cows studied developed at least one clinical or subclinical disease after calving. Incidence of individual diseases was 8.8% for retained placenta, 4.2% for clinical hypocalcemia, 11.7% for clinical mastitis, 41.1% for metritis, 19.9% for subclinical hypocalcemia and 16.6% for subclinical ketosis. Lower postpartum cholesterol in cows was associated with developing severe metritis or having more than one clinical disease after calving. For every 0.4 mmol/L decrease in serum cholesterol cows were nearly twice as likely to be diagnosed with multiple clinical diseases after calving. Higher BHBA concentrations and lower calcium concentrations during week 1 were associated with severe cases of metritis. Low serum calcium concentration during week 1 was also associated with developing more than one clinical disorder after calving. In conclusion, the incidence of postpartum diseases can be high even in grazing herds and lower serum cholesterol concentrations were associated with occurrence of clinical postpatum disorders.     

Relationship of physiological factors to placental retention in dairy cattle

Various physiological and environmental factors were examined for possible association with retention of the fetal membranes in a herd experiencing a high incidence of this problem. Data were collected on 116 multiparous and primiparous cows during the first lactation of the trial and 57 multiparous cows during the second lactation of the trial. No mineral or heavy metal deficiencies or toxicities were detected in the herd and injections of selenium and/or vitamins A, D and E during the prepartum period were not beneficial. Also, no common disease entity could be found in this herd. Placental retention rates observed were 28% and 42% in the first and second lactations, respectively, of this study. The incidence of retained placenta was higher in cows giving birth to twins or male calves, and following abortions, stillbirths or placental retention at the previous parturition. Seasonal effects varied, with a higher retention rate in the warm season in the first lactation and in the cold season in the second lactation. Factors examined that did not show a statistically significant relationship to the placental retention rate included: blood serum vitamin A and β-carotene concentrations; age or lactation number; calf birth weight; presence of serum antibodies to leucosis or chlamydia; incidence of milk fever or ketosis; and services per conception, days open and gestation length of the pregnancy prior to retention. Cows with retained placenta subsequently had longer postpartum intervals to first ovulation and more uterine infections, foot problems and mastitis than cows without retained placenta.     

Effect of disease on reproduction in the dairy cow: a meta-analysis

Effects on reproduction of dystocia, stillbirth, abortion, milk fever, retained placenta, metritis, cystic ovaries, anestrus, ketosis, displaced abomasum, locomotor disorders, and mastitis were reviewed. Papers were considered if they provided quantitative estimates of diseases on days to first estrus, days to first service, conception rate at first service, days from first service to conception, days to conception or days open, calving interval, conception rates at various days post partum (dpp), and number of services per conception or per cow. Only papers in English in peer-reviewed journals were selected for analysis of post 1960 data from intensive dairy regions. Seventy papers fulfilled the selection criteria. Summary estimates of disease effects were calculated according to meta-analysis methods, and study designs were described in detail to identify possible heterogeneity of the results. Stillbirth, milk fever, displaced abomasum and mastitis had no effect on reproduction. Clinical ketosis, dystocia and retained placenta were associated with 2 to 3 more days to first service and with a 4 to 10% lower conception rate at first service, resulting in 6 to 12 more days to conception. Locomotor disorders were associated with an average increase of 12 d to conception, with wide variation depending on lesions and stage of occurrence. Metritis was associated with 7 more days to first service, 20% lower conception rate at first service, resulting in 19 more days to conception. Cystic ovaries were associated with 6 to 11 more days to first service and with 20 to 30 more days to conception. Anestrus was associated with 26 more days to first service and with an 18% lower conception rate at first service, resulting in 41 more days to conception. Abortion was associated with 70 to 80 more days to conception.     

An Epidemiological and Genetic Study on Registered Diseases in Finnish Ayrshire Cattle

The epidemiology and genetic variability of the most common dairy cow diseases were examined. This paper describes the data set, lactation incidence rates and culling during lactation. The data set consisted of the lactation records of 73,368 Finnish Ayrshire dairy cows. Each cow was under observation for 2 days before and 305 days after calving. Lactational incidence rates (%) for the most common diseases were: ovulatory dysfunction 7.0, ketosis 6.0, acute mastitis 5.4, an oestrus and suboestrus 5.2, retained placenta 4.5, parturient paresis 3.8 and teat injury 2.6. Multiple logistic regression was utilized to investigate the possible effects of certain factors on culling. The model predicted the log odds for culling as an additive function of the explanatory factors. Using the estimated odds and forming the odds ratios it was possible to investigate, relative risks between any combination of groups of the explanatory factors. The risk of culling increased with parity after the second parturition, and with increasing herd milk yield. Mastitis and parturient paresis had positive associations with culling, while ketosis and infertility had negative associations. Heritability estimates for culling in various parity groups were from 2 % to 9 % on the binomial scale corresponding from 5 % to 14 % on the normal scale. There was a neagtive genetic correlation between culling and previous milk production.     

Cumulative Risk of Bovine Mastitis Treatments in Denmark,Finland, Norway and Sweden

Data from the national dairy cow recording systems during 1997 were used to calculate lactation-specific cumulative risk of mastitis treatments and cumulative risk of removal from the herds in Denmark, Finland Norway and Sweden. Sweden had the lowest risk of recorded mastitis treatments during 305 days of lactation and Norway had the highest risk. The incidence risk of recorded mastitis treatments during 305 days of lactation in Denmark, Finland, Norway and Sweden was 0.177, 0.139, 0.215 and 0.127 for first parity cows and 0.228, 0.215, 0.358 and 0.204 for parities higher than three, respectively. The risk of a first parity cow being treated for mastitis was almost 3 times higher at calving in Norway than in Sweden. The period with the highest risk for mastitis treatments was from 2 days before calving until 14 days after calving and the highest risk for removal was from calving to 10 days after calving in all countries.The study clearly demonstrated differences in bovine mastitis treatment patterns among the Nordic countries. The most important findings were the differences in treatment risks during different lactations within each country, as well as differences in strategies with respect to the time during lactation mastitis was treated.     

The effect of nutritional management of the dairy cow on reproductive efficiency

The cause of low fertility in dairy cows is multifactorial. Poor nutrition during the dry and early postpartum periods results in reduced glucose, insulin, insulin-like growth factor (IGF-I) and low LH pulse frequency with concomitant increases in beta-hydroxy butyrate, non-esterified fatty acids (NEFA) and triacylglycerol. Cows must mobilize large lipid, but also some protein reserves, with a consequent increased incidence of such metabolic disorders as hypocalcaemia, acidosis, ketosis, fatty liver and displaced abomasums. The occurrence of milk fever and ketosis affects uterine contractions, delays calving and increases the risk of retained foetal membranes (RFM) and endometritis. The nutritional risk factors that cause RFM are hypocalcaemia, high body condition score (BCS) at calving and deficiencies in Vitamin E and selenium. The risk factors for endometritis are hypocalcaemia, RFM, high triacylglycerol and NEFA. Thus, metabolic disorders predispose cows to gynaecological disorders, thereby reducing reproductive efficiency. Cows that are overconditioned at calving or those that lose excess body weight are more likely to have a prolonged interval to first oestrus, thereby prolonging days open. Nutritionally induced postpartum anoestrus is characterized by turnover of dominant follicles incapable of producing sufficient oestradiol to induce ovulation due to reduced LH pulse frequency. High nutrition can also increase metabolic clearance rate of steroid hormones such as progesterone or oestradiol. Lower concentrations of oestradiol on the day of oestrus are highly correlated with the occurrence of suboestrus, thereby making the detection of oestrus in high yielding cows even more difficult. Nutrition also affects conception rate (CR) to AI. Cows that develop hypocalcaemia, ketosis, acidosis or displaced abomasums have lower CRs and take longer to become pregnant. Excessive loss of BCS and excess protein content of the ration can reduce CR while supplemental fats that attenuate the production of F2alpha can improve CR. The increased metabolic clearance rate of progesterone (P4), which decreases blood concentrations during early embryo cleavage up to the blastocyst stage is associated with decreased CRs. In conclusion, poor nutritional management of the dairy cow, particularly before and after calving, is a key driver of infertility.     

Subclinical hypocalcaemia follows specific time-related and severity patterns in post-partum Holstein cows

Hypocalcaemia is a common metabolic disorder of post-parturient dairy cows; enhancement of our knowledge regarding Ca dynamics would improve cow health and welfare. This study investigated the presence of time- and severity-related subclinical hypocalcaemia (SCHCa) patterns in Holstein cows after calving and their association with diseases during the first week of lactation. A total of 938 cows from nine herds were blood sampled on days 1, 2, 4 and 8 post-partum, and serum Ca concentration was measured with atomic absorption. Subclinical ketosis (serum β-hydroxybutyrate≥1.2 mmol/L) and cases of retained foetal membranes, metritis (MET), mastitis, ketosis and displaced abomasum (DA) were recorded. Using receiver operating characteristic (ROC) analysis, the SCHCa cut-off was identified at serum Ca ≤ 2.09 mmol/L. Hierarchical and two-step cluster analysis classified cows to seven clusters based on test day cow Ca records and overall SCHCa status. Two clusters (NORM and HIGH) included 318 normocalcaemic cows and five clusters (SCH-1 to −5) those that were at least once subclinically hypocalcaemic (n = 620). A second ROC analysis was performed in order to distinguish mild from severe cases of SCHCa in these 620 cows; this cut-off was identified at 1.93 mmol/L. The associated risk of disease with Ca clustership was assessed with generalized linear mixed models. Overall incidence of SCHCa was 66.1%. Clusters SCH-1 and SCH-2 included cows with short-term SCHCa of day 1 and day 2, respectively, while SCH-3 included cows with severe and prolonged SCHCa extending to day 4 and beyond. Clusters SCH-4 and SCH-5 included cows with delayed SCHCa, which culminated on days 4 and 8, respectively. Compared to NORM cows in HIGH had lower risk of MET and no cases of DA. Cows in SCH-3 had higher risk of being diagnosed with retained foetal membranes, DA or any disease during the study period. Cows in SCH-5 had higher risk of being diagnosed with ketosis, subclinical ketosis or any disease. In conclusion, there are multiple normocalcaemic and hypocalcaemic patterns that are differently associated with disease risk.     

Incidence of Some Diseases in Connection with Parturition in Dairy Cows

The incidence of dystocia, uterine, prolapse, retained placenta, puerperal metritis and vaginal prolapse was investigated in 283 herds over a period of eight years (about 2,590 cows per year). The incidence of dystocia (0.012 cases per cow and year), of uterine prolapse (0.002) and puerperal metritis (0.002) varied with the monthly variation in parturition. Retained placenta (incidence 0.025) occurred more frequently in March-June relative to parturition. The cows then calving were older than average. Vaginal prolapse (incidence 0.002) was also commoner in the spring months. Herds with a high incidence of retained placenta also showed more mastitis, ketosis and parturient paresis.     

Pten对奶牛乳腺上皮细胞活力及乳蛋白合成的影响

Pten作为抑癌基因,参与调控细胞生长、粘附、凋亡以及其它细胞活动.目前,国内外关于Pten在奶牛乳腺发育过程中表达及调节的研究鲜有报道.为了揭示Pten的表达与奶牛乳腺发育与泌乳之间的关系,本研究应用qRT-PCR技术检测Pten在不同泌乳时期和不同乳品质的奶牛乳腺组织中的表达差异,进而应用脂质体转染方法,通过siRNA介导的RNA干扰技术改变Pten基因在奶牛乳腺上皮细胞中的表达量,CASY法检测细胞活力,用ELISA试剂盒检测细胞分泌β-酪蛋白的含量,采用qRT-PCR、Western 印迹等技术检测Pten对奶牛乳腺上皮细胞中乳蛋白相关信号通路基因表达的影响.结果显示,泌乳期高乳品质奶牛乳腺组织中Pten表达水平显著低于泌乳期低乳品质及干乳期奶牛;Pten基因沉寂后,细胞活力提高,β-酪蛋白质量浓度增加,CSN2、AKT、MTOR、STAT5表达量增加.研究表明,Pten可通过抑制细胞活力和乳蛋白分泌而影响泌乳.     

Accurate detection of dairy cow mastitis with deep learning technology: a new and comprehensive detection method based on infrared thermal images

Mastitis is one of the most common diseases in dairy cows and has a negative impact on their welfare and life, causing significant economic losses to the dairy industry. Many attempts have been made to develop a detection method for mastitis using thermal infrared thermography. However, the use of this detection technique to determine the health of the cow's udder is susceptible to external factors, resulting in inaccurate detection of dairy cow mastitis. Therefore, this study explored a new and comprehensive detection method of dairy cow mastitis based on infrared thermal images. This method combined the left and right udder skin surface temperature (USST) difference detection method with the ocular surface temperature and USST difference detection method with improvements. The effect of external factors on dairy cow USST was effectively reduced. In addition, after comparing different target localisation algorithms, this paper used the You Only Look Once v5 (YOLOv5) deep learning network model to obtain the temperature information of eyes and udders, and mastitis detection of dairy cows was performed. A total of 105 dairy cows passing through a passage were randomly selected from the thermal infrared video and detected by the new and comprehensive detection method, and the results of cow mastitis detection were compared with somatic cell count. The results showed that the accuracy, specificity, and sensitivity of mastitis detection were 87.62, 84.62, and 96.30%, respectively. Using the YOLOv5 deep learning network model to locate the key parts of the cow had a good effect, with an average accuracy of 96.1%, and an average frame rate of 116.3f/s. The detection accuracy of dairy cow mastitis by deep learning technology combined with the detection method in this paper reached 85.71%. The results showed that the new and comprehensive detection method based on infrared thermal images can be used for the detection of dairy cow mastitis with high detection accuracy. This method can reduce the influence of external factors and can be integrated into the automatic identification system of dairy mastitis based on YOLOv5 to realise on-site monitoring of dairy mastitis.     

Review: welfare of dairy cows in continuously housed and pasture-based production systems

There is increasing interest in the use of continuous housing systems for dairy cows, with various reasons put forward to advocate such systems. However, the welfare of dairy cows is typically perceived to be better within pasture-based systems, although such judgements are often not scientifically based. The aim of this review was to interrogate the existing scientific literature to compare the welfare, including health, of dairy cows in continuously housed and pasture-based systems. Although summarising existing work, knowledge gaps and directions for future research are also identified. The scope of the review is broad, examining relevant topics under three main headings; health, behaviour and physiology. Regarding health, cows on pasture-based systems had lower levels of lameness, hoof pathologies, hock lesions, mastitis, uterine disease and mortality compared with cows on continuously housed systems. Pasture access also had benefits for dairy cow behaviour, in terms of grazing, improved lying/resting times and lower levels of aggression. Moreover, when given the choice between pasture and indoor housing, cows showed an overall preference for pasture, particularly at night. However, the review highlighted the need for a deeper understanding of cow preference and behaviour. Potential areas for concern within pasture-based systems included physiological indicators of more severe negative energy balance, and in some situations, the potential for compromised welfare with exposure to unpredictable weather conditions. In summary, the results from this review highlight that there remain considerable animal welfare benefits from incorporating pasture access into dairy production systems.     

The effect of out-wintering pad design on dirtiness score, somatic cell score and mastitis incidence in dairy cows

This study aimed to compare three woodchip out-wintering pad (OWP) designs, and indoor cubicle housing with regard to cow dirtiness scores during the winter housing period, and udder health during both the winter period and the following lactation, for spring-calving dairy cows. The treatments were: an uncovered (UP) and covered (CP) OWP with a concrete feed apron; an uncovered OWP with self-feed silage pit provided directly on the woodchips (SP); and indoor cubicle housing (IC). Data were compared during 2 years: year 1 was a case study while year 2 was an experimental study. In year 1, treatments were UP (space allowance = 12 m2/cow), CP (6 m2/cow) and IC. In year 2, all three OWP designs (12 m2/cow) were compared with IC. Animals were assigned to treatments at the end of lactation in the autumn, and remained there while dry until calving the following spring. Subsequently, all cows were at pasture during lactation. Outcome measures for analysis were cow dirtiness score, somatic cell score (SCS) and incidence of clinical mastitis during the dry period and during lactation. Quarter milk samples were also taken at drying off, calving and 3 weeks post partum both years, and at approximately 113 days in milk in year 2. Samples were analysed for presence of mastitis-causing agents and SCS was determined. Sub-clinical mastitis was diagnosed when cows had an SCS greater than 200 000, or California mastitis test greater than 1 in at least one quarter. In year 1, cows in CP were dirtier than cows in the other two treatments. These animals also had the highest SCS during lactation and tended to have more mastitis-causing agents isolated from quarter milk samples. In year 2, when all cows were stocked at the same density, cows in the sheltered OWP (i.e. CP) had similar dirtiness scores to cows in cubicles and significantly lower dirtiness scores than cows in the unsheltered OWP designs, i.e. UP and SP. However, there were no effects on SCS or quarter sample results. Cleaning of OWP's stocked at 12 m2/cow reduced cow dirtiness scores. However, cleaning of CP in year 1 when cows were stocked at 6 m2/cow had no effect on dirtiness scores. We conclude that dry cows stocked at 12 m2/cow on OWP's are unlikely to have udder health problems in the subsequent lactation. Furthermore, provision of shelter and cleaning of the woodchips are management factors that help to keep cows clean on OWP's.     

Postpartum oxytocin treatment for prevention of retained placentas

Some dairymen are attempting to reduce the incidence of retained placentas in their herds by routinely injecting oxytocin following parturition. Since there was little or no experimental evidence to support such a practice, a study was designed to test the influence of early postpartum oxytocin injection on the incidence of retained placentas. The study was designed so that every other cow in the University of Illinois dairy herd would receive an intramuscular injection of 100 IU oxytocin within three to six hours following calving. If the animal expelled the membranes before three hours she was placed in the control group. Two hundred cows calved during the one year study. In the 100 cow control group, twelve cows retained their fetal membranes whereas in the 100 cow treated group eight retained the placenta.     

Transplacental 45Ca and 32P flux in the guinea pig: effect of maternal hypercalcaemia and hypocalcaemia

Transplacental 45Ca and 32P flux was measured across the in situ perfused guinea-pig placenta under conditions of acute maternal hypocalcaemia and hypercalcaemia. Maternal hypercalcaemia induced acutely by calcium gluconate infusion caused an increase in maternal-to-fetal 45Ca flux which was proportional to the increase in maternal plasma ionized calcium concentration. Acute maternal hypocalcaemia was induced by EGTA infusion and resulted in a decrease in maternal plasma ionized calcium concentration proportional to a corresponding decrease in transplacental 45Ca transfer. A bolus of calcium gluconate caused a transient decrease in 32P flux, whereas EGTA administration was without significant effect on transplacental 32P transfer. Calcium transport across the placenta is not saturated under conditions of maternal normocalcaemia and may be altered according to acute changes in maternal plasma calcium concentration. Thus, control of maternal-to-fetal calcium transfer does not appear to be at the placental level. This suggests that fetal calcium homeostasis may be regulated by the fetus itself.     

Identifying risk factors for poor hind limb cleanliness in Danish loose-housed dairy cows

The objective of this study was to identify possible risk factors for poor cow hind limb cleanliness in Danish loose-housed, lactating dairy cows. The study was conducted as a cross-sectional study of 1315 cows in 42 commercial Danish dairy herds with primarily Danish Holstein cows. The effect of four cow-level factors (parity, days in milk, daily lying time and lameness) and eight herd-level factors (herd size, milk production, milking system, floor type, access to pasture grazing, floor scraping frequency, hoof bathing frequency and hoof washing frequency) on the risk of having dirtier hind limbs were analysed using ordinal logistic regression fitting a proportional odds model. Cow hind limb cleanliness was scored using an ordinal score from 1 to 4: 1 being clean and 4 being covered in dirt. The odds ratios (ORs) estimated from the proportional odds model depict the effect of a risk factor on the odds of having a higher rather than a lower cleanliness score. First parity cows had an increased risk of being dirtier compared with third parity or older cows (OR=1.70). Compared with late lactation, early and mid lactation were associated with an increased risk of being dirtier (OR=2.07 and 1.33, respectively). Decreasing the daily time lying by 30 min was associated with an increased risk of being dirtier (OR=1.05). Furthermore, an increased risk of being dirtier was found in herds with no pasture access (OR=3.75).