Alterations of endotoxin distribution across different biofluids and relevant inflammatory responses by supplementing L-theanine in dairy cows during heat stress

The present trial was performed to reveal the regulatory effects of L-theanine on the levels of lipopolysaccharide (LPS) endotoxin within different biofluids, as well as relevant inflammatory responses of dairy cattle under heat stress conditions. Thirty lactating Chinese Holstein dairy cattle (189 ± 47 d in milk, and 2 ± 1 parities) were allocated in a completely randomized design to each of 3 dietary treatments: the control (CON, 0 g/d per cow L-theanine), the low L-theanine dosage treatment (LL, 16 g/d per cow L-theanine), and the high L-theanine dosage treatment (HL, 32 g/d per cow L-theanine). This trial consisted of 38 d (7 d for adaption and 31 d for data and sample collection), and sample collection for rumen liquid, blood plasma or serum, and milk were conducted on the d 27 and 38, respectively. Dairy cattle were constantly exposed to environmental heat stress during this experiment according to the recorded temperature-humidity index (THI). In the LL treatment, LPS concentration in rumen liquid was higher (P < 0.05), whilst LPS densities in plasma and milk were lower (P < 0.05) than those of the CON. Supplementing L-theanine at 2 dosages both significantly lowered (P < 0.05) the level of interleukin (IL)-1β in the serum. Results of the present study suggested that L-theanine could be a promising additive in reducing the detrimental effects of heat stress on dairy cows, and L-theanine supplementation at 16 g/d per cow is preferred because it reduced the LPS translocation into the peripheral blood and LPS accumulation in the milk, as well as mitigated LPS-induced inflammatory reactions in dairy cows during heat stress. Further studies are necessitated to investigate the underlying mechanisms of L-theanine in LPS alteration and inflammation alleviation.     

Hepatic steroid inactivating enzymes,hepatic portal blood flow and corpus luteum blood perfusion in cattle

Production from the corpus luteum (CL) and/or hepatic steroid inactivation impacts peripheral concentrations of P4, which can alter reproductive performance. Our primary objective was to examine hepatic steroid inactivating enzymes, portal blood flow, and luteal blood perfusion at 10 days post‐insemination in pregnant versus non‐pregnant beef and dairy cows. Twenty early lactation Holstein cows and 20 lactating commercial beef cows were utilized for this study. At day 10 post‐insemination, hepatic portal blood flow and CL blood perfusion were measured via Doppler ultrasonography. Liver biopsies were collected and frozen for later determination of cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A), uridine diphosphate‐glucuronosyltransferase (UGT) and aldo‐keto reductase 1C (AKR1C) activities. Pregnancy was determined at day 30 post‐insemination and treatment groups were retrospectively assigned as pregnant or non‐pregnant. Data were analyzed using the mixed procedure of SAS. Steroid metabolizing enzyme activity was not different (p > .10) between pregnant versus non‐pregnant beef or dairy cows. Hepatic portal blood flow tended (p < .10) to be increased in pregnant versus non‐pregnant dairy cows. Luteal blood perfusion was increased (p < .05) in pregnant versus non‐pregnant dairy cows. Pregnant dairy cows appear to have an increased rate of hepatic clearance of P4 in combination with increased synthesis from the CL. This could account for the lack of difference in peripheral P4 concentrations between pregnant and non‐pregnant dairy cows. This study highlights the relevance of further investigation into steroid secretion and inactivation and their impact on the maintenance of pregnancy in cattle.     

Impact of α‐amylase supplementation on energy balance and performance of high‐yielding dairy cows on moderate starch feeding

In dairy cows, exogenous α‐amylase is suggested to improve starch utilization and positively affect performance and health traits linked to energy balance and fertility. In a 1‐year feeding experiment, 421 cows were orally supplemented with α‐amylase (treatment: 12.5 g/kg dry matter (DM) addition rate to a concentrated feed) or non‐supplemented (control) on the basis of an ad libitum total mixed ration (TMR). Every cow was allocated to a high‐ (≥32 kg milk/day) or late‐lactation group (<32 kg milk/day), in which the TMR starch content was 220 ± 20.8 g/kg DM and 183 ± 24.8 g/kg DM, respectively. The energetic effect of α‐amylase supplementation seemed to be exclusively related to the high‐lactation stage (5–100 days in milk) in primiparous cows, where the daily milk yield was 32 ± 0.49 versus 31 ± 0.50 kg per cow in the treatment versus control group (P < 0.05). The pluriparous cows did not benefit from the supplementation that way. In neither primiparous nor pluriparous cows, was the milk composition, the fat‐to‐protein ratio, the somatic cell score, the backfat thickness, serum total bilirubin, β‐hydroxybutyrate and the fertility found to be systematically affected by α‐amylase supplementation.     

Feed degradability,rumen fermentation and blood metabolites in response to essential oil addition to fistulated non‐lactating dairy cow diets

The effects of essential oils (EOs) on ruminal nutrient disappearance, rumen fermentation and blood metabolites in fistulated non‐lactating dairy cows were studied. Four fistulated non‐lactaing dairy cows were used in a 4 × 4 Latin square design; the experiment consisted of four periods of 21 days in each period, with the first 14 days for adaptation followed by 7 days of measurement period. Animals were fed 3 kg/day of 21% crude protein (CP) concentrate and ad libitum corn silage. Treatments were: (i) control; (ii) 2 mL Allicin/cow/day; (iii) 2 mL zingiberene/cow/day; and (iv) 2 mL citral/cow/day. The results demonstrated that EOs increased dry matter and neutral detergent fiber degradabilities at 48 and 72 h, but had no effect on acid detergent fiber and CP degradabilities. EOs did not change ruminal pH, ammonia nitrogen, protozoa, volatile fatty acid concentrations and blood glucose but reduced blood urea nitrogen at 4 h.     

Endometrial gene expression in primiparous dairy cows at the end of the voluntary waiting period is affected by nutrition: Total mixed ration vs increasing levels of herbage allowance

The study postulated that differential nutritional management during the early lactation period would be reflected in endometrial expression of genes related to embryo growth at the end of the voluntary waiting period. Thus, the effect of the combined use of total mixed ration (TMR) and grazing under different herbage allowances during the first 75 days post‐partum (DPP) on endometrial gene expression was evaluated in primiparous dairy cows. Cows were blocked by body weight, age and body condition score and randomly assigned to three grazing treatments: high (HA, 30 kg DM per cow per day), medium (MA, 15 kg DM per cow per day) and low (LA, 7.5 kg DM per cow per day) herbage allowance (mixed pasture, 2,600 kg DM per ha) plus 8 kg DM of supplement or TMR (55% forage, 45% concentrate) fed ad libitum (TMR) from calving to 75 DPP. At 57 DPP, cows were synchronized for oestrus (day 0, 68 DPP) and at day 7, endometrial biopsies were obtained. The nutritional treatment did not affect insulin, IGF‐1 and leptin concentrations on days 0, 4 or 7. Expression of IGF1, IGFBP3, IGFBP4, ADIPOR1 and ADIPOR2 mRNA was significantly affected by the nutritional treatment. Endometrial IGF1 and IGFBP4 mRNA were twofold greater in TMR and HA than MA and LA cows. Expression of IGFBP3 and ADIPOR1 mRNAs was greater in TMR and HA than MA cows, but did not differ from LA cows. All groups had greater expression of ADIPOR2 mRNA than MA cows. This study provided solid evidence of the importance of nutritional management during early lactation on uterine environment at the end of the voluntary waiting period. The greater expression of genes related to embryo growth and uterine function (IGF system, progesterone and adiponectin receptors) in cows fed diets maximizing energy intake suggests a favourable environment for embryonic growth, which may explain the improved reproductive performance of cows in good energy balance.     

Cytological endometritis diagnosed at artificial insemination in repeat breeder dairy cows

This study aimed to (i) assess the prevalence of cytological endometritis (CYTO) diagnosed at artificial insemination (AI); (ii) evaluate the effect of CYTO on the pregnancy outcome of the same AI sample; and (iii) determine the risk factors associated with CYTO diagnosed at AI in repeat breeder (RB) dairy cows. We analysed the productive and reproductive performances of 146 RB Holstein‐Friesian cows. To obtain a CYTO sample at AI, we used the cytotape technique. Generalized mixed effect models were computed to find the risk factors associated with the pregnancy and CYTO outcome. Based on ≥1% PMN cut‐off point, the CYTO prevalence at AI in RB cows was 25.3%. The overall pregnancy at AI was 44.2%. The conception rate in CYTO‐positive (n = 37) RB cows was 29.7% versus 49.5% for CYTO‐negative (n = 109) cows. A RB cow diagnosed CYTO positive at AI had 0.47 [odds ratio (OR)] odds to become pregnant in comparison with a CYTO‐negative cow. Cows that produced more milk than their counterparts in this study had increased odds (OR = 1.01) to be CYTO positive at AI. A novel risk factor positively associated with CYTO diagnosed at AI in RB cows was the level of daily milk urea (OR = 1.11). To conclude, CYTO at the moment of AI had a significantly negative effect on the pregnancy outcome in RB dairy cows. However, as only one of fourth of RB cows is affected with CYTO at AI, it may not be considered a key element associated with the RB syndrome.     

Evaluation of Oestrous Detection in Dairy Cattle Comparing an Automated Activity Monitoring System to Visual Observation

The objective of the study was to evaluate an automated activity monitoring (AAM) system for oestrous detection in dairy cows. Specifically, we set out to determine the oestrous detection efficiency and accuracy of the AAM system and to compare reproductive performance of cows detected either by AAM, by visual observation (VO) or by at least 1 of the 2 methods (EOM). A total of 1004 potential cow‐periods from 348 cows were analysed. Oestrous detection rates (EDR) were calculated for 21 day (VWP+21), 42 day (VWP+42), and 63 day (VWP+63) after voluntary waiting period (VWP). Oestrous detection rate did not differ between AAM (42.1%) and VO (37.3%) during VWP+21 (p > 0.05) but was significantly higher in EOM (56.3%, p < 0.05). Oestrous detection by AAM achieved an efficiency (number of correctly detected oestruses/total number of cow‐periods*100) of 35.6% and an accuracy (number of correctly detected oestruses/(number of true+ false oestruses)*100) of 83.8%. Visual observation resulted in an efficiency of 34.3% and accuracy of 75.1%. Pregnancy rate at 200 DIM was higher in AAM (66.8%) and EOM (68.8%) than in VO (57.1%, p < 0.05). Cows detected by AAM (p < 0.05) showed a 1.37 times greater risk to conceive than cows detected by VO as the reference (p < 0.05). The results show that an automated activity monitoring system can support oestrous detection in dairy cattle. The exclusive use of such a system, however, cannot be recommended.     

Acute phase response in lactating dairy cows during hyperinsulinemic hypoglycaemic and hyperinsulinemic euglycaemic clamps and after intramammary LPS challenge

The link between energy availability, turnover of energy substrates and the onset of inflammation in dairy cows is complex and poorly investigated. To clarify this, plasma inflammatory variables were measured in mid‐lactating dairy cows allocated to three groups: hyperinsulinemic hypoglycaemic clamp, induced by insulin infusion (HypoG, n = 5); hyperinsulinemic euglycaemic clamp, induced by insulin and glucose infusion (EuG; n = 6); control, receiving a saline solution infusion (NaCl; n = 6). At 48 h after the start of i.v. infusions, two udder quarters per cow were challenged with 200 μg of E. coli lipopolysaccharide (LPS). Individual blood samples were taken before clamps, before LPS challenge (i.e. 48 h after clamps) and 6.5 h after. At 48 h, positive acute phase proteins (posAPP) did not differ among groups, whereas albumin and cholesterol (index of lipoproteins), negative APP (negAPP), were lower (p < 0.05) in EuG compared to NaCl and HypoG. The concentration of IL‐6 was greater in EuG (p < 0.05) but only vs. HypoG. At 6.5 h following LPS challenge, IL‐6 increased in the NaCl and EuG clamps (p < 0.05), while TNF‐α increased (p < 0.05) in the EuG only. Among the posAPP, haptoglobin markedly increased in EuG (p < 0.05), but not in NaCl (p = 0.76) and in HypoG; ceruloplasmin tended to decline during LPS challenge, the reduction was significant when all animals were considered (p < 0.05). Conversely, all the negAPP showed a marked reduction 6.5 h after LPS challenge in the three groups. In conclusion, EuG caused an inflammatory status after 48‐h infusion (i.e. decrease of negAPP) and induced a quicker acute phase response (e.g. marked rise of TNF‐α, IL‐6) after the intramammary LPS challenge. These data suggest that the simultaneous high availability of glucose and insulin at the tissue‐level makes dairy cows more susceptible to inflammatory events. In contrast, HypoG seems to attenuate the inflammatory response.     

Cow‐specific diet digestibility predictions based on near‐infrared reflectance spectroscopy scans of faecal samples

This study was designed to obtain information on prediction of diet digestibility from near‐infrared reflectance spectroscopy (NIRS) scans of faecal spot samples from dairy cows at different stages of lactation and to develop a faecal sampling protocol. NIRS was used to predict diet organic matter digestibility (OMD) and indigestible neutral detergent fibre content (iNDF) from faecal samples, and dry matter digestibility (DMD) using iNDF in feed and faecal samples as an internal marker. Acid‐insoluble ash (AIA) as an internal digestibility marker was used as a reference method to evaluate the reliability of NIRS predictions. Feed and composite faecal samples were collected from 44 cows at approximately 50, 150 and 250 days in milk (DIM). The estimated standard deviation for cow‐specific organic matter digestibility analysed by AIA was 12.3 g/kg, which is small considering that the average was 724 g/kg. The phenotypic correlation between direct faecal OMD prediction by NIRS and OMD by AIA over the lactation was 0.51. The low repeatability and small variability estimates for direct OMD predictions by NIRS were not accurate enough to quantify small differences in OMD between cows. In contrast to OMD, the repeatability estimates for DMD by iNDF and especially for direct faecal iNDF predictions were 0.32 and 0.46, respectively, indicating that developing of NIRS predictions for cow‐specific digestibility is possible. A data subset of 20 cows with daily individual faecal samples was used to develop an on‐farm sampling protocol. Based on the assessment of correlations between individual sample combinations and composite samples as well as repeatability estimates for individual sample combinations, we found that collecting up to three individual samples yields a representative composite sample. Collection of samples from all the cows of a herd every third month might be a good choice, because it would yield a better accuracy.     

Effects of Feeding Dry Glycerol to Primiparous Holstein Dairy Cows on Follicular Development,Reproductive Performance and Metabolic Parameters Related to Fertility during the Early Post‐partum Period

This study examined the effects of dry glycerol supplementation on follicular growth, post‐partum interval to first ovulation, concentration of serum metabolites and hormones related to fertility, body condition score (BCS) and body weight (BW) in primiparous Holstein dairy cows. Sixty primiparous Holstein dairy cows were randomly assigned to two groups (control: n = 30 and glycerol supplemented: n = 30). Dry glycerol (250 g/day/cow) was fed as a top dressing to the common lactating total mixed ration (TMR) from parturition to 21 days post‐partum. Ovaries were examined four times using ultrasonography on days 13, 19, 25 and 36 post‐partum to determine ovarian follicular growth. Concentration of serum metabolites and hormones was determined weekly. Body condition score was evaluated weekly from weeks 1 to 5 after parturition, and BWs were recorded three times on days 1, 11 and 21 during the experimental period. The cows fed dry glycerol had more large follicles (p < 0.0001) and corpora lutea (CL) (p = 0.02) compared with the control cows. Days to the first ovulation (p = 0.06), days to first oestrus (p = 0.05), services per conception (p = 0.06) and days open (p = 0.004) were positively affected by dry glycerol supplementation. Serum concentration of glucose and insulin was higher in dry glycerol‐supplemented cows (p = 0.1; p = 0.06, respectively). Feeding glycerol had no effect on mean serum concentrations of β‐hydroxybutyrate, non‐esterified fatty acids and IGF‐1 during the experimental period. However, significant differences were observed at concentration of BHBA and IGF‐1 (p = 0.02 and p = 0.04, respectively) between two groups on day 21 after calving. The cows in the glycerol‐fed group had higher serum progesterone concentrations on days 33 (p = 0.007) and 36 (p = 0.004) after calving. Supplemented cows had lower body condition loss during weeks 1–5 after calving compared with the control cows (0.34 vs 0.41 BCS). In week 13 post‐partum, the proportion of cycling cows was 83.3 and 69.9% for those which received supplemented or non‐supplemented diet, respectively. These results demonstrated that feeding dry glycerol as a glucogenic supply may be useful to improve negative energy balance and reproductive efficiency in young cows which calve with high requirement of energy.     

Milk production and blood metabolites of dairy cattle as influenced by thermal-humidity index

The effects of high thermal stress on serum protein metabolites, milk production of transition dairy cows in semi-arid areas in South Africa were evaluated. Forty, ±?8 months pregnant, Jersey heifers (±?26 months) in zero grazing management were selected during summer from two semi-arid communal areas. Summer thermal-humidity index (THI) of the areas were THI-1 (72–83: extreme caution) and THI-2 (75–87: danger). Blood samples were collected (21 days pre-partum, and 21 and 75 days post-partum) and analysed for serum protein metabolites. Milk yield was recorded daily and samples collected for milk fat, protein, lactose and urea nitrogen analysis. Heifers in THI-2 had lower (P?<?0.05) total serum proteins, albumin and blood urea nitrogen than THI-1. Post-calving, cows in THI-1 had higher (P?<?0.05) TP (73.4 vs 67.9 g/l) and BUN (4.61 vs 3.77 mmol/l) at 21 DIM, and lower (P creatinine at 21 and 75 DIM than THI-2 group. Milk yield, fat and protein in THI-2 were all lower (P?<?0.05) than THI-1 21DIM. The results confirm that heat stress affects utilisation of nutrients in transition dairy cows.

     

Acupuncture prevents the postpartum reduction in matrix metalloproteinase type‐2 immunoexpression,tissue concentration and enzyme activity in bovine caruncles

The objectives of this study were to determine the effects of acupuncture in dairy cows (Bos taurus) on caruncular matrix metalloproteinase type‐2 (MMP2) at 0, 2 and 4 hr after calving. Acupuncture (n = 6) was applied at 0 and 2 hr after calving to 6 points that relax the cervix and stimulate uterine contractions. Controls (n = 9) were kept in a stanchion for 15 min without acupuncture. All of the cows in the study delivered their placenta in <4 hr. Formalin‐fixed caruncles were paraffin‐embedded and subjected to routine immunohistochemistry to determine MMP2 expression, which was scored by a single observer. Flash frozen caruncles were homogenized, and protein concentration was determined. MMP2 concentrations were calculated using commercial bovine ELISAs. MMP2 enzyme activity was determined using zymography. The mean value for each time point for each cow was used to calculate the mean ± SEM for each treatment group. MMP2 was predominantly localized to the epithelial and subepithelial stromal cells of the caruncles in both treatment groups. MMP2 immunoexpression was lower 4 hr after calving in the control cows (p = 0.012) but not in the acupuncture treated cows indicating that acupuncture treatment maintained MMP expression. MMP2 tissue concentration was lower 2 hr after calving in the control cows (p = 0.048) but not in the acupuncture treated cows. MMP2 enzyme activity decreased from 0 to 2 hr after calving in control cows (p = 0.046) but not in acupuncture treated cows. This study provides physiologic evidence for the effects of acupuncture on the bovine reproductive tract and substantiates the use of this treatment in cases of placental retention.     

Exploration of factors determining milk production by Holstein cows raised on a dairy farm in a temperate climate area

In this study, we examined factors that affected milk production by cows raised in a temperate climate area. We conducted this study on a large dairy farm containing approximately 2000 Holstein cows, located in a temperate climate area. We collected 7803 calving records for 4069 cows from 2012 to 2016. We then assessed the effect of hot weather on milk yield by examining three climate factors: season, maximum temperature (MAX), and the temperature and humidity index (THI). We found that increases in heat stress caused linear decreases in milk yield (P?<?0.05). Additionally, the effects of the three climate factors on milk yield varied depending on cow parity and days open (P?<?0.05). Thus, management procedures should consider cow parity and lactating stage to minimize the negative effects of heat stress on milk production. We also found that the lowest Akaike information criterion value was obtained in our model when using THI for 305-day milk yield. This suggests that THI is a more accurate variable for evaluating heat stress than MAX or season.

     

Detection of 11 beta‐hydroxysteroid dehydrogenase type 1, the glucocorticoid and mineralocorticoid receptor in various adipose tissue depots of dairy cows supplemented with conjugated linoleic acids

Early lactating cows mobilize adipose tissue (AT) to provide energy for milk yield and maintenance and are susceptible to metabolic disorders and impaired immune response. Conjugated linoleic acids (CLA), mainly the trans‐10, cis‐12 isomer, reduce milk fat synthesis and may attenuate negative energy balance. Circulating glucocorticoids (GC) are increased during parturition in dairy cows and mediate differentiating and anti‐inflammatory effects via glucocorticoid (GR) and mineralocorticoid receptors (MR) in the presence of the enzyme 11β‐hydroxysteroid dehydrogenase type 1 (11βHSD1). Activated GC are the main ligands for both receptors in AT; therefore, we hypothesized that tissue‐specific GC metabolism is effected by varying amounts of GR, MR and 11βHSD1 and/or their localization within AT depots. Furthermore, the lipolytic and antilipogenic effects of CLA might influence the GC/GR/MR system in AT. Therefore, we aimed to localize GR and MR as well as the expression pattern and activity of 11βHSD1 in different AT depots during early lactation in dairy cows and to identify potential effects of CLA. Primiparous German Holstein cows were divided into a control (CON) and a CLA group. From day 1 post‐partum (p.p.) until sample collection, the CLA group was fed with 100 g/d CLA (contains 10 g each of the cis‐9, trans‐11 and the trans‐10, cis‐12‐CLA isomers). CON cows (n = 5 each) were slaughtered on day 1, 42 and 105 p.p., while CLA cows (n = 5 each) were slaughtered on day 42 and 105 p.p. Subcutaneous fat from tailhead, withers and sternum, and visceral fat from omental, mesenteric and retroperitoneal depots were sampled. The localization of GR and 11βHSD1 in mature adipocytes – being already differentiated – indicates that GC promote other effects via GR than differentiation. Moreover, MR were observed in the stromal vascular cell fraction and positively related to the pre‐adipocyte marker Pref‐1. However, only marginal CLA effects were observed in this study.     

Fertility of Holstein cows and heifers submitted to timed artificial insemination and receiving one or two doses (12 h apart) of semen

The objective of this retrospective study was to assess the effect of receiving a single (n = 50,285) or double (n = 4392) artificial insemination (AI), 12 h apart, within a timed artificial insemination protocol on pregnancy per AI (P/AI) in nulliparous heifers (inseminated with either sex-sorted or conventional semen) and pluriparous Holstein cows in a commercial dairy herd. Also, this study aimed to investigate the relationship between temperature-humidity index (THI) and time of the first AI and fertility. Fertility of cows receiving two AI with normothermia (THI <68) was higher (p < .05) than cows receiving a single AI (42.9% vs. 36.4%). P/AI of cows receiving two AI with severe heat stress (THI >85) was higher (p < .05) than cows receiving a single AI (21.0% vs. 12.6%). Regardless of heat stress conditions, applying the first AI in the morning increased (p < .05) P/AI in cows with double AI than in cows whose first AI occurred in the afternoon (38.4 vs. 33.3%). With moderate heat stress, and sexed-sorted semen, P/AI to timed AI was higher (65.0 vs. 51.9%; p < .05) in heifers receiving double AI than those serviced once. It was concluded that double AI, 12 h apart, enhanced fertility at timed AI than herd mates with a single AI, particularly with heat stress at breeding.     

Evaluation and Comparison of 2 On‐Farm Tests for Estimating Somatic Cell Count in Quarter Milk Samples from Lactating Dairy Cattle

Background

The somatic cell count (SCC) is commonly used to monitor udder health and diagnose subclinical intramammary infection (IMI) in dairy cattle.

Hypothesis

The Somaticell test (ST) 2 and California mastitis test (CMT) are clinically useful cow‐side tests for diagnosing subclinical IMI.

Animals

One hundred and eleven dairy cows at dry‐off and 92 cows within 4–7 days postcalving.

Methods

Quarter foremilk samples were obtained and analyzed with a DeLaval cell counter (DCC, reference method), 1 ST, and CMT. The ST was run in a simulated cow‐side manner using milk at 37°C instead of 0–8°C as recommended by the manufacturer. Test performance for diagnosing IMI (DCC SCC >200,000 cells/mL) was evaluated by calculating the area under the receiver operating characteristic curve (AUC) and the kappa coefficient (κ) at the optimal cut‐point for each test. The effect of milk/reagent temperature also was evaluated.

Results

Compared to the reference method, the ST run in a simulated cow‐side manner had an AUC = 0.68 and κ = 0.24 at dry‐off, and AUC = 0.74 and κ = 0.40 in fresh cows. The CMT performed much better than the ST in diagnosing subclinical IMI with AUC = 0.88 and κ = 0.77 at dry‐off, and AUC = 0.87 and κ = 0.76 in fresh cows. The measured ST value decreased with increasing temperature of the milk/reagent mixture.

Conclusions/Clinical Importance

The ST is optimized for use on milk at 0–8°C and is therefore designed for on‐farm use on refrigerated milk samples. The ST is not suited for use as a cow‐side screening test for IMI because the milk temperature exceeds the recommended range for the test.     

Daidzein enhances immune function in late lactation cows under heat stress

Heat stress decreases natural immunity making cows more vulnerable to diseases. A previous study reported that daidzein can enhance animal resistance to heat stress and regulate animal immunocompetence. However, it is unclear whether daidzein regulates the immune performance of late lactation cows under heat stress. In this study, late lactation cows in four groups were raised in hot weather and fed with basic diet, basic diet plus 200, 300, 400 mg/day daidzein, respectively, and the experimental period was 60 days. Blood was collected to examine the changes of serum total protein (TP), albumin (ALB), immunoglobulin G (IgG), interferon alpha (IFN‐α), and interleukin‐2 (IL‐2). We found the levels of serum IgG and INF‐α were significantly higher in late lactation cows after 300 and 400 mg/day daidzein treatment compared to those in the control group and 200 mg/day daidzein treatment (P < 0.05 or P < 0.01). Moreover, 300 and 400 mg/day daidzein treatment markedly increased serum IL‐2 (P < 0.01), while the levels of serum TP and ALB were not changed by any concentration of daidzein treatment (P > 0.05). Daidzein can enhance the immunocompetence of late lactation cows and strengthen cow resistance to heat stress.     

Association of California Mastitis Test Scores with Intramammary Infection Status in Lactating Dairy Cows Admitted to a Veterinary Teaching Hospital

Background

Subclinical mastitis is of concern in veterinary hospitals because contagious mastitis pathogens might be unknowingly transmitted to susceptible cows and then back to their farm of origin.

Objectives

To evaluate the California mastitis test (CMT) as an indicator of intramammary infection (IMI) in lactating dairy cows admitted to a veterinary hospital.

Animals

A total of 139 admissions of 128 lactating dairy cows admitted to the University of Illinois Veterinary Teaching Hospital over a 2‐year period.

Methods

A retrospective study with a convenience sample was conducted. Medical records of cows with CMT results and milk culture results for the day of admission were reviewed. Breed, age, season, maximum CMT score for the 4 quarters, maximum CMT score difference, and clinical diagnosis were evaluated as predictors of IMI by the chi‐square test and stepwise logistic regression.

Results

An IMI was identified in 51% of quarters. For cows admitted without evidence of clinical mastitis, the sensitivity of a CMT score ≥trace in predicting an IMI on a quarter or cow basis was 0.45 and 0.68, respectively. The distributions of maximal quarter CMT score and the maximum difference in quarter CMT score for cows without evidence of clinical mastitis did not differ (P = 0.28, P = 0.84, respectively) for cows with and without IMI. Stepwise logistic regression did not identify significant predictors of IMI in cows without clinical mastitis.

Conclusions

Lactating dairy cattle admitted to a veterinary hospital should be managed as if they have an IMI, even in the absence of clinical mastitis.     

Comparative biochemical profiles,production and reproduction status of the post‐partum dairy cows with and without purulent vaginal discharge

Purulent vaginal discharge (PVD) is a prevalent uterine disease of dairy cows during the puerperium that affects the milk production and affects the profitability of farms. The objectives of this study were to evaluate the biochemical profile, the body condition score, the milk production of cows with PVD and the effects PVD on reproductive performance. A total of 338 Holstein dairy cows aged from 3 to 5 years, from three commercial dairy farms, from Brazil, were used. Blood samples were collected within 25 ± 3 days post‐partum from Holstein dairy cows without PVD (control cows, n = 242) and cows with PVD (n = 96), based on scoring of the vaginal discharge. The body condition score and milk production were recorded on the day of sampling. The biochemical profile encompassed albumin, urea, gamma‐glutamyl transferase, calcium, fibrinogen and cholesterol concentrations. The number of services per pregnancy was lower (p < 0.01), and the number of days until first insemination and the median time to pregnancy were higher in cows with PVD (p < 0.01) when compared with control cows. Milk production and body condition score were lower (p < 0.01) in cows with PVD than in control group. Cows with PVD had lower (p < 0.05) serum albumin, urea, calcium and cholesterol concentrations, and higher serum gamma‐glutamyl transferase activity and fibrinogen concentration than cows without PVD. Our results show that cows with PVD have changes in the biochemical profile and negative effects on production and reproduction performance.     

Plasma Concentrations of Pregnancy‐Associated Glycoproteins Measured Using Anti‐Bovine PAG‐2 Antibodies on Day 120 of Gestation Predict Abortion in Dairy Cows Naturally Infected with Neospora caninum

The present study sought to determine: (i) the effects of Neospora caninum infection and twin pregnancy on plasma pregnancy‐associated glycoprotein‐2 (PAG‐2) concentrations throughout pregnancy and (ii) whether plasma PAG‐2 concentrations could predict abortion in N. caninum‐infected cows. The study was performed on a commercial Holstein‐Friesian dairy herd in northeastern Spain and the final data included those recorded in 53 non‐aborting and 19 aborting animals. Blood samples were collected immediately before pregnancy diagnosis (on Days 40, 90, 120, 150, 180 and 210 post‐insemination) in non‐aborting cows or until the time of abortion detection in aborting cows. General lineal models (GLM) repeated measures anova revealed the different behaviour of PAG‐1 and PAG‐2, and significant effects of Neospora seropositivity, cool season and twin pregnancy on plasma PAG‐2 concentrations throughout gestation (between‐subject effects). In addition, based on the odds ratios, the likelihood of abortion increased in Neospora‐seropositive cows (by a factor of 7.0) compared to seronegative animals and decreased in cows with a high plasma PAG‐2 concentration (>4.5 ng/ml) on Day 120 of pregnancy (by a factor of 0.24), compared to the remaining cows. In conclusion, there is a relationship between plasma PAG‐2 concentrations and the risk of abortion in Neospora‐infected dairy cows. Thus, plasma PAG concentrations measured using anti‐boPAG‐2 antiserum on Day 120 of gestation could serve as an indicator of the abortion risk in N. caninum infected animals; values <4.5 ng/ml indicating a high risk of abortion in chronically infected animals.