Prevalence of urovagina and its effects on reproductive performance in Holstein cows

Two hundred fifty-eight Holstein cows (n = 344 lactations) from seven dairy herds were examined every month by vaginoscopy and transrectal palpation to determine the prevalence of urovagina, to investigate its effects on fertility, and to determine some risk factors for urovagina. Accumulation of urine in the vagina of a cow was diagnosed as urovagina and was classified into mild (urine only on the floor of vagina), moderate (urine covering less than or equal to half portion of the external cervical os), or severe (urine covering more than half or whole portion of the external cervical os). In total, 26.7% of lactations had urovagina (mild 11.3%, moderate 11.0%, and severe 4.4%). Survival analysis was used to derive the case definition of clinically relevant urovagina based on the factors associated with increased time to conception. Only moderate (hazard ratio [HR] = 0.39) and severe (HR = 0.20) degrees of urovagina were associated with reduction in pregnancy rate and thus defined as clinically relevant urovagina. Cows with clinically relevant urovagina had decreased AI submission rate (HR = 0.52) and pregnancy rate (HR = 0.35), required more inseminations per conception (5 vs. 2; P < 0.001), had more days open (370 vs. 136; P < 0.001), and were more likely not to get pregnant by 210 d postpartum (odds ratio [OR] = 6.62) and to be culled for any reasons (OR = 5.32) or for reproductive reasons (OR = 9.54) compared with those in cows with no urovagina. Cows with clinically relevant urovagina had a higher risk of endometritis (36.4% vs. 9.2%; P < 0.001) compared with that in cows without urovagina. Cow, low BCS at first postpartum examination (OR = 2.85), endometritis within 60 d (OR = 2.50), and horizontal vulva (OR = 9.30) were risk factors for urovagina. In conclusion, 15.4% of lactations had clinically relevant urovagina that increased the risk of endometritis and had detrimental effects on fertility. Individual susceptibility, low BCS, and horizontal vulva increased the risk of diagnosing urovagina in Holstein cows.     

Association between endometritis and endometrial cytokine expression in postpartum Holstein cows

The endometrium regulates the inflammatory response after infection by production and release of cytokines and chemokines. The objective was to compare gene expression of important pro-inflammatory (TNFα, IL-1β, IL-6) and anti-inflammatory (IL-10) cytokines, and the main neutrophil chemokine (IL-8), from calving to Week 7 after calving, in cows that developed endometritis and healthy control cows. Uterine biopsies were obtained at calving and at Weeks 1, 3, 5 and 7. Endometritis was evaluated at Week 5 by uterine lavage and cytology; cows with ≥ 10% neutrophils were considered to have endometritis. Real-time RT-PCR threshold values (Ct) were used to calculate the fold difference in gene expression, using the 2^−ddCt method, normalized to GAPDH and calibrated to the average dCt for all cows at calving. Serum IL-8 concentrations were measured with ELISA. The analysis included 28 cows (11 had endometritis) for the PCR data and 44 cows (20 had endometritis) for ELISA. Expression of the TNFα gene in uterine tissue was decreased in cows with endometritis compared to control cows at calving (P = 0.09) and at Week 1 (P = 0.05). Iterleukin-1β gene expression tended to be decreased (P = 0.08) in cows with endometritis compared to control cows at Week 1, but tended to be increased (P ≤ 0.10) at Weeks 5 and 7. Cows with endometritis had increased (P < 0.05) IL-6 gene expression at calving and at Week 7 compared to control cows. Interleukin-8 gene expression was increased (P = 0.03) in endometritic cows compared to control cows at Week 7. Uterine disease was not significantly associated with IL-10 gene expression. A lower local level of expression of pro-inflammatory cytokines in the endometrium soon after calving might impair activation of inflammation and clearance of bacteria, and lead to development of endometritis.     

Evaluation of the effectiveness of intrauterine treatment with formosulphathiazole of clinical endometritis in postpartum dairy cows

In cattle, elimination of bacterial contamination from the uterine lumen after parturition is often delayed or compromised, and pathogenic bacteria can persist, causing uterine disease and infertility. The aim of this study was to compare the clinical and bacteriologic recovery following a single intrauterine administration of formosulphatiazole, cephapirin or placebo in cows with clinical endometritis. Cows (n = 80), no less than 28 days postpartum, with clinical endometritis were enrolled in the study. Endometritis was diagnosed by a complete reproductive examination, including rectal palpation, ultrasonography, vaginoscopy and uterine swab. All cows were randomly assigned to receive one of three intrauterine treatments (T0): 2500 mg of formosulphatiazole (Group A); 500 mg of cephapirin (Group B); placebo (4250 mg of propylene glycol; Group C). Cows were examined at the first estrus after treatment or no more than 30 days after (T1). Bacteria isolated were E. coli, A. pyogenes, Pasteurella spp. and Streptococcus spp. After treatment, in Group A and B only 6/30 (20.0%) and 6/24 (25.0%) cows showed a positive bacteriologic culture (P > 0.05), while in Group C the number of positive animals was significantly higher (19/26; 73.1%; P < 0.05). At T0, total clinical scores were similar between the three groups (Group A: 5.84 ± 1.07; Group B: 5.91 ± 1.0; Group C: 5.62 ± 1.17; P > 0.05) and indicative of clinical endometritis. At T1, endometritis scores were significantly lower than those reported before uterine infusion (P < 0.05); however, Group A and B score, 0.4 ± 0.9 and 1.0 ± 2.1, respectively, correspond to no and slight endometritis, while animals in Group C reported a total endometritis score significantly higher (4.6 ± 3.5; P < 0.05) corresponding to endometritis. In the present study, a commercial formosulphatiazole preparation was as effective as cephapirin and more effective than placebo for the treatment of clinical endometritis.     

Evaluation of cytokine expression by blood monocytes of lactating Holstein cows with or without postpartum uterine disease

Whereas neutrophils are the main phagocytic leukocytes, monocytes and macrophages are actively involved in immunomodulation after infection. Recent studies have demonstrated that neutrophil function is impaired by the state of negative energy balance around parturition, and that cows that develop uterine disease have a greater degree of negative energy balance than healthy cows. The objectives of this study were to compare monocyte gene expression and protein secretion of selected cytokines from calving to 42 d after calving in Holstein cows that did or did not develop uterine disease. Real time quantitative RT-PCR (Tumor necrosis factor-α (TNFα), Interleukin (IL)-1β, IL-6, IL-8 and IL-10) and ELISA (TNFα, IL-1β and IL-8) were used to evaluate cytokine response following in vitro stimulation of blood-derived monocytes with irradiated E. coli. Relative to unstimulated cells, E. coli-stimulated monocytes from cows with metritis had lower gene expression of key pro-inflammatory cytokines than healthy cows from calving to 14 d after calving (TNFα at 0, 7, and 14 d after calving, IL-1β and IL-6 at 7 and 14 d after calving; P < 0.05). There were no significant differences between groups for expression of IL-8 or the anti-inflammatory cytokine IL-10. This was due, in part, to higher gene expression in unstimulated monocytes (TNFα, IL-1β, IL-6 and IL-10) in early lactation from cows with metritis. Expression of mRNA in stimulated cells (relative to housekeeping genes) was lower for TNFα (7 and 14 d postpartum) and for IL-10 (7 and 14 d postpartum) in cows with metritis. Concentration of TNFα was lower in the culture medium of E. coli-stimulated monocytes from cows with metritis than healthy cows at calving and 7 and 21 d after calving (P < 0.05). Circulating cytokine concentrations were not different between groups for IL-8 and were below the limits of detection for TNFα and IL-1β. Cytokine gene expression and production were similar between healthy cows and cows that developed endometritis, diagnosed cytologically at 42 d after calving. We concluded that altered levels of expression and production of pro-inflammatory cytokines postpartum could contribute to impaired inflammatory response and predispose cows to development of metritis.     

Defining delayed resumption of ovarian activity postpartum and its impact on subsequent reproductive performance in Holstein cows

The objectives of this study were to derive a useful case definition of delayed resumption of ovarian activity, based on factors associated with reduced fertility, and to assess its impact on subsequent reproductive performance in Holstein cows (Bos taurus). Milk samples were collected twice weekly from 219 cows from four commercial herds, and whole-milk progesterone concentrations were determined with an enzyme-linked immunosorbent assay. Ovulation was considered to have occurred 5 d before the first rise of milk progesterone concentration above the basal level. Survival analysis was used to derive a case definition of delayed resumption of ovarian activity postpartum based on factors that were predictive of reduced pregnancy rate. First postpartum ovulation occurring beyond 35 d postpartum was associated with a reduced pregnancy rate (hazard ratio [HR] = 0.50; P < 0.001) and was defined as delayed resumption of ovarian activity; overall, 75 (34.9%) cows were in this category. These cows were more likely not to conceive on first artificial insemination (odds ratio [OR] = 2.85; P = 0.01) and more likely not to become pregnant within 100 d (OR = 3.30; P = 0.001) and 210 d (OR = 3.20; P < 0.001) postpartum compared with cows with normal resumption of ovarian activity. Furthermore, 13 (6%) cows that ovulated within 35 d postpartum had a prolonged (≥14 d) interval between either first and second or second and third luteal phases postpartum. A prolonged interluteal interval was also associated with a reduced pregnancy rate (HR = 0.35; P = 0.02). Days open (mean ± SEM) were greater (P = 0.0002) in cows with delayed resumption of ovarian activity (213 ± 13 d) and in cows with prolonged interluteal interval (220 ± 37 d) than in cows with normal resumption of ovarian activity (152 ± 9 d). In conclusion, first ovulation occurring beyond 35 d postpartum was defined as delayed resumption of ovarian activity, and the first ovulation occurring within 35 d postpartum but the absence of luteal activity ≥14 d between two consecutive luteal phases was defined as a prolonged interluteal interval; both abnormalities adversely affected the subsequent reproductive performance of Holstein cows.     

Inflammatory cytokine concentrations in uterine flush and serum samples from dairy cows with clinical or subclinical endometritis

The objective of this study was to compare the concentrations of inflammatory cytokines in uterine flush and serum from healthy postpartum dairy cows and cows with clinical or subclinical endometritis. Clinical endometritis was diagnosed by observation of vaginal discharges (>50% pus) and subclinical endometritis was diagnosed by evaluation of uterine cytology (neutrophils >18%) at 4 weeks postpartum. Uterine flush was obtained from 48 cows at 4, 6, and 8 weeks postpartum for evaluation of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, IL-8, and IL-10 concentrations. Serum samples were obtained from 34 cows just after calving and at 1, 2, 4, 6, and 8 weeks postpartum for evaluation of TNF-α, IL-1β, and IL-6 concentrations. Concentrations of TNF-α, IL-6, and IL-10 were greater (P < 0.05) in cows with clinical endometritis than in cows with subclinical endometritis and healthy controls, whereas concentrations of IL-8 in both cows with clinical and subclinical endometritis were greater (P < 0.005) than in controls. Overall, IL-6 and IL-10 concentrations decreased during the postpartum period. IL-1β concentrations in cows with clinical endometritis decreased (P < 0.0005) during the postpartum, whereas concentrations in cows with subclinical endometritis and controls did not change significantly with time; at 4 weeks postpartum, concentrations were greater (P < 0.0001) in cows with clinical endometritis. There were no significant effects of group, sampling time, or interaction on serum cytokine concentrations. In conclusion, cows with endometritis have greater inflammatory cytokine concentrations in uterine flush than healthy cows, but no differences were observed in serum.     

Use of reagent test strips for diagnosis of endometritis in dairy cows

The use of leukocyte esterase (LE), protein, and pH tests were evaluated on widely available urinary test strips (Multistix 10 SG; Bayer Corporation, Elkart, IN, USA) on uterine lavage samples as a potential cow-side test for the diagnosis of cytologic endometritis. Uterine lavage samples of 563 lactating Holstein cows between 40 and 60 days postpartum from 28 herds were evaluated. Endometrial cytology was used as the reference for endometritis, with a cutoff point of ≥10% neutrophils. All three (LE, protein, and pH) were increased in cows with cytologic endometritis and the associations were highly significant. Optimal cutoff points determined by receiver operating characteristic analysis for LE, protein, and pH were ≥++, ≥300 mg/dL, and ≥7.0, respectively. Combining the results for LE and pH improved the performance of the test strip, but this resulted in a group of cows (20.6% of cows) which were approximately equally likely (46% with endometritis and 54% without endometritis) to have cytologic endometritis or not, and therefore could not be accurately classified. The direct relationship between reagent strip test and reproductive performance was also evaluated. Reproductive impairment due to endometritis was restricted to multiparous cows; significantly decreased reproductive performance was observed for multiparous cows with lavage fluid LE ≥+++ (154 vs. 115 median days not-pregnant), as well as cows with pH ≥ 7.0 (150.5 vs. 111.5 median days not-pregnant), but not in cows with high protein, even at the highest cutoff point. In conclusion, reagent strip test results were strongly associated with cytologic endometritis and reproductive impairment; however, in comparison with conventional cytology, the performance of reagent strip as an alternative test was relatively poor and may require further refinement.     

Risk factors for postpartum ovarian cysts and their spontaneous recovery or persistence in lactating dairy cows

Cystic ovarian disease is a major cause of reproductive failure and economic loss for the dairy industry. Many cysts that develop during the early postpartum period regress spontaneously. However, it is difficult to decide at what point it would be more cost effective to treat ovarian cysts than to wait for spontaneous recovery. The objective of this study was to analyze risk factors for the development of the ovarian cystic condition during early and late postpartum, and for its persistence or recovery during the pre-service period in lactating dairy cows. Using multiple logistic regression, we analyzed data derived from 873 lactating dairy cows from a single herd. An ovarian cyst was diagnosed if it was possible to observe a single follicular structure with an antrum diameter > or = 25 mm in the absence of a corpus luteum in three sonograms performed at 7-day intervals. The cystic condition was denoted as early if the cyst was diagnosed 43-49 days postpartum, and late if detected 57-63-day postpartum. Spontaneous cyst regression before 60-day postpartum was regarded as early cystic recovery. For the early cystic group, there were no significant effects of lactation number, body condition score on prepartum Day 60, at parturition or on postpartum Day 30, or of body condition loss from parturition to 30-day postpartum. Cows calving in summer were 2.6 times more likely to develop ovarian cysts than those giving birth in winter. The risk of having a cyst was 1.9 times higher in cows with an abnormal puerperium. A 1-kg increase in milk yield raised the risk of cysts by a factor of 1.05. A 1-unit increase in body condition score (scale from 1 to 5) from prepartum Day 60 to parturition increased the risk of cyst development 8.4 times. Milk production and lactation number were negatively correlated with spontaneous early cyst recovery. A 1-kg decrease in milk production increased the probability of cyst recovery by a factor of 1.06, and a 1-unit drop in lactation number was associated with a 1.4-fold increased probability of cyst recovery. For the late cystic group, there were no significant effects of abnormal puerperium and body score data, except for a prepartum change in body score. Calving season (Odds ratio: 2.3), lactation number (Odds ratio: 1.36), increased milk production (Odds ratio: 1.05) and increased body condition score during the prepartum period (Odds ratio: 4.3) were all related to an increased risk of ovarian cysts. The probability of having a late cyst was 36.6 times greater in cows with early cysts. These findings suggest that it would be profitable to treat multiparous cows having cysts very early in the postpartum period, while treatment of primiparous cows should be delayed, at least until the end of the pre-service period, to provide the opportunity for spontaneous recovery.     

Effects of live weight adjusted feeding strategy on plasma indicators of energy balance in Holstein cows managed for extended lactation

In early lactation, most of the dairy cows are in negative energy balance; the extent and duration depend in part on the feeding strategy. Previous studies showed an increased lactation milk yield by use of a live weight (LW) adjusted feeding strategy with a high energy diet before and a reduced energy diet after LW nadir compared with a standard diet throughout lactation. The objective of the present study was to examine how such an individualized feeding strategy affects plasma indicators of energy status. It was hypothesized that an energy-enriched diet until LW nadir will reduce the severity of the negative energy balance, and that the reduction in diet energy concentration from LW nadir will extend the negative energy balance period further. Sixty-two Holstein cows (30% first parity) were managed for 16 months extended lactation and randomly allocated to one of two feeding strategies at calving. Two partially mixed rations were used, one with a high energy density (HD) and a 50 : 50 forage : concentrate ratio, and one with a lower energy density (LD, control diet) and a 60 : 40 forage : concentrate ratio. Half of the cows were offered the HD diet until they reached at least 42 days in milk and a LW gain⩾0 kg/day based on a 5-days LW average, and were then shifted to the LD diet (strategy HD-LD). The other half of the cows were offered the LD diet throughout lactation (control strategy LD-LD). Weekly blood samples were drawn for analysis of plasma metabolites and hormones. Before the shift in diet, the HD-LD cows had higher glucose and lower beta-hydroxybutyrate and non-esterified fatty acids (NEFA) concentrations than the LD-LD cows. After the shift until 36 weeks after calving, plasma NEFA was higher in HD-LD than LD-LD cows. Insulin and insulin-like growth factor-1 were not affected by the feeding strategy. To conclude, in early lactation, the energy-enriched diet reduced the negative energy balance. Plasma NEFA was higher in HD-LD than LD-LD cows from diet shift until 36 weeks after calving, indicating a carry-over effect of the early lactation HD diet to late lactation metabolism.     

Sensible and latent heat loss from the body surface of Holstein cows in a tropical environment

The general principles of the mechanisms of heat transfer are well known, but knowledge of the transition between evaporative and non-evaporative heat loss by Holstein cows in field conditions must be improved, especially for low-latitude environments. With this aim 15 Holstein cows managed in open pasture were observed in a tropical region. The latent heat loss from the body surface of the animals was measured by means of a ventilated capsule, while convective heat transfer was estimated by the theory of convection from a horizontal cylinder and by the long-wave radiation exchange based on the Stefan–Boltzmann law. When the air temperature was between 10 and 36°C the sensible heat transfer varied from 160 to –30 W m^–2, while the latent heat loss by cutaneous evaporation increased from 30 to 350 W m^–2. Heat loss by cutaneous evaporation accounted for 20–30% of the total heat loss when air temperatures ranged from 10 to 20°C. At air temperatures >30°C cutaneous evaporation becomes the main avenue of heat loss, accounting for approximately 85% of the total heat loss, while the rest is lost by respiratory evaporation.Part of first authors doctoral thesis     

Association of genetic polymorphism inGH gene with milk production traits in Beijing Holstein cows

Associations were analysed between polymorphisms of the growth hormone gene (GH-MspI) (localized in intron 3) and milk production traits of Beijing Holstein cows (a total of 543 cows). Polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method was used for identification of various geno-types. Frequencies of genotypes were 0.77, 0,21 and 0.02 for A/A, A/B and B/B, respectively. The frequency of theGH ^A allele is 0.875. The results of the least squares means show that in all three lactations, theGH A/A cows yielded more milk (P < 0.01 for lactation I andP 0.05 for lactations II and III), whereas A/B cows showed higher milk fat content than A/A individuals (P < 0.05 for lactations I and II, andP < 0.01 for lactation III). The A/A cows yielded more fat than A/B individuals (P < 0.01 only in lactation I). The A/A cows yielded more milk protein than A/B individuals (P < 0.01 for lactations I, II, and III). The A/A cows produced milk of higher protein content than of A/B individuals (P < 0.05 only in lactation II).     

Impact of three THI levels on somatic cell count,milk yield and composition of multiparous Holstein cows in a subtropical region

In Egypt, cow's milk represents 52.11% of the total milk production. Climatic condition is mainly expected to impact the welfare and productive performance of livestock animals. Thus, we aimed to explore the impact of temperature-humidity index (THI) on somatic cell count (SCC), milk production and composition on daily milk test records (33600) of Holstein cows under subtropical Egyptian conditions with different levels of THI. Our results revealed that daily milk yield and composition (fat%, protein %, yielded fat, yielded protein and the percentage of lactose) were higher in low THI (31.91 kg, 3.91%, 3.22%, 418 kg, 349 kg and 4.20%, respectively) when compared with high THI. SCC significantly increased 36% from low to high THI. In addition to, it was increased with advanced parities 231.11% from 2nd to 7th parities. At high THI level, SCC was negatively correlated with total MY (r=−0.12 P<0.05), 305 MY (r=−0.16 P<0.05), protein % (r=−0.15 P<0.01), fat% (r=−0.14 P<0.01) and lactose % (r=−0.26 P<0.01). The current study concluded that dairy cows performance was better in most of the investigated parameters at low THI than those in high THI. Thus, indicating a detrimental effect of THI on both welfare and economic return.     

Secretion of prostaglandins and leukotrienes by endometrial cells in cows with subclinical and clinical endometritis

The aims of this study were (1) to measure the secretion of prostaglandin F_2α (PGF_2α), prostaglandin E₂ (PGE₂), leukotriene B₄ (LTB₄), and leukotriene C₄ (LTC₄) by endometrial cells collected by a cytobrush from healthy cows and cows with subclinical and clinical endometritis in the fourth week postpartum, and (2) to evaluate the relationship between the mediators' levels of secretion and the number of polymorphonuclear neutrophils (PMNs) in the uterine smears of cows with subclinical endometritis. The study included cows without any signs of clinical endometritis (n = 63) and cows with clinical endometritis as a positive control (ENDOM, n = 12). Two different threshold ratios (>5% and >18% of PMNs) were used to categorize the cows without clinical signs as with or without cytologic endometritis (CE). Considering the first or second threshold, the animals with CE were included in group CE POS I or CE POS II, whereas the healthy cows were assigned to group CE NEG I or CE NEG II, respectively.     

Endometrial expression of selected transcripts involved in prostaglandin synthesis in cows with endometritis

Several cytokines and prostaglandins play an important role in preparing the endometrium for implantation and mediating pro-inflammatory events. The aim of the present study was to examine mRNA expression of interleukin 1α (IL-1α), interleukin receptor antagonist (IL-1-RN), cytosolic prostaglandin E synthase (cPGES), microsomal PGES (mPGES-1 and mPGES-2) and lipocalin-type PGDS (L-PGDS) in the bovine endometrium. Endometrial epithelium samples were collected ex vivo from cows with different status of health at day 21-27 postpartum on a dairy farm. Three groups (n = 9 animals each) were defined: (1) healthy cows with no signs of endometritis (control group), (2) cows with subclinical endometritis, and (3) cows with signs of clinical endometritis. Oestrous cycle-dependent mRNA expression pattern was investigated using bovine endometrial epithelial cells from healthy uteri collected at the abattoir. These uteri were classified into post-ovulatory, early-to-mid luteal, late luteal or pre-ovulatory phase (n = 8 animals for each cycle phase). After collecting endometrial epithelium using the cytobrush-method, mRNA analysis was performed by real-time RT-PCR. L-PGDS, IL-1α and IL-1-RN mRNA were expressed significantly higher (P < 0.05) in the endometrium of cows with subclinical or clinical endometritis compared with healthy cows. A twofold lower cPGES mRNA expression (P < 0.05) was detected in cows with subclinical endometritis compared to healthy cows. L-PGDS and IL-1-RN mRNA expression was increased (P < 0.05) after ovulation compared with the pre-ovulatory or luteal phase, respectively. These results support the hypothesis that a dys-regulated cytokine and/or prostaglandin profile in the uterus could be induced by subclinical endometritis or clinical endometritis.     

Effects of feeding dry propylene glycol to early postpartum Holstein dairy cows on production and blood parameters

In all, 18 multiparous and 19 primiparous Holstein dairy cows were used in a completely randomized design with restrictions to evaluate the effects of feeding propylene glycol (PG) as a dry product, via two delivery methods, on production and blood parameters. PG treatments were administered from parturition through 21 days postpartum. Treatments were: (i) control, no PG; (ii) top dress, 162.5 g PG/day by top dressing onto the total mixed ration (TMR) and; (iii) mixing, 162.5 g PG/day as a part of the TMR by incorporating it into the TMR. PG used was a dry product which contained 65% pure PG and 35% silicon dioxide as the dry carrier. Coccygeal blood was sampled on 4, 7, 14 and 21 days in milk (±1.50 pooled s.d.). Supplementation of dry PG by top dressing onto, or incorporating into, the TMR had no effects on average dry matter intake, milk yield and composition, serum insulin, serum and plasma metabolites and milk ketones. Concentrations of urine ketones tended (P = 0.10) to be reduced by PG supplementation from 41.5 to 15.2 mg/dl. Supplementation of PG tended (P = 0.07) to decrease the incidence for subclinical ketosis from 39% to 24% and 13% for cows fed a TMR supplemented with no dry PG, with dry PG as a top dress and dry PG as a part of the TMR, respectively. It is concluded that supplementing PG as a dry product via incorporating into the TMR is as effective as when used as a top dress, based on the efficacies of both delivery methods to numerically reduce urine ketones concentrations and, therefore, the incidence for subclinical ketosis during the first 21 days of lactation. However, it should be noted that the number of cows used in the current study was minimal, and more cows are needed to confirm the efficacy of supplementing PG as a dry product on reducing the prevalence of subclinical ketosis in dairy cows during the first month of lactation.     

长江下游地区中国荷斯坦奶牛生乳中菌落总数的影响因素分析

【背景】随着人们生活水平和健康意识的提高,作为部分乳制品的原料,生乳的质量安全问题显得尤为重要。【目的】检测长江下游地区某集约化牧场中国荷斯坦奶牛生乳中菌落总数、总大肠菌群数的真实水平,同时对影响其变化的生理因素和环境因素进行探讨。【方法】以中国荷斯坦奶牛生乳为研究对象,用乳房炎快速诊断剂检测乳房炎感染情况,菌落总数、总大肠菌群数和环境细菌数的检测方法参照国家标准。对采集的生乳样本进行细菌常规分离鉴定,同时收集乳成分变化数据。【结果】多因素方差分析结果表明,不同泌乳阶段和不同产奶量对荷斯坦奶牛生乳中菌落总数的影响显著(P0.05)和极显著(P0.01);体况、泌乳阶段、胎次、产奶量及乳区对大肠菌群数均无显著影响(P0.05)。夏季生乳的菌落总数、大肠菌群数均极显著地高于其他季节(P0.01);场区内各牛舍的不同卫生环境及细菌数对菌落总数、大肠菌群数的影响均在显著以上(P0.05)。不同乳房炎的感染程度对菌落总数影响极显著(P0.01)。细菌鉴定结果是葡萄球菌属和杆菌属感染居多,链球菌属感染几乎没有。菌落总数的变化对乳蛋白率影响不显著(P0.05),对乳脂率的影响极显著(P0.01)。【结论】随机采样泌乳牛群的不同生理和病理状况、外界不同饲养条件及卫生环境对生乳中菌落总数和大肠菌群数有不同程度的影响,生乳的乳脂率与细菌总数变化负相关。     

Phenotyping of leukocytes and granulocyte and monocyte phagocytic activity in the peripheral blood and uterus of cows with endometritis

This study was a comparative evaluation of selected immunological parameters in peripheral blood and uterine wash samples from cows with a normal postpartum period compared with cows with endometritis. We aimed to determine the usefulness of these parameters in monitoring the puerperium. In total, 40 cows were included in the study: 20 had endometritis (experimental group), and 20 did not have uterine inflammation (control group). Animals were chosen on the basis of cytological and bacteriological test results. The tests were conducted 5, 22, and 40 days postpartum. In both groups, flow cytometric analysis of the surface molecules CD4, CD8, CD21, CD25, and CD14 in the peripheral blood and uterine washings was performed. Granulocyte and monocyte phagocytic activity was determined using a commercial Phagotest kit that was adapted for flow cytometry. The percentage of phagocytic granulocytes and monocytes in both the peripheral blood and the uterine washings was significantly lower for cows in the experimental group compared with the control group (P < 0.01). A significant decrease (P < 0.01) in the percentage of CD4+, CD25+, CD14+, and CD4 + CD25^high leukocyte subpopulations was also observed in the peripheral blood of cows with endometritis. A significant decrease (P < 0.01) in CD21+ lymphocytes and an increase in CD8+ lymphocytes was detected in uterine washings. The results of this work indicate that cell immunity dysfunction may be the main factor causing advanced inflammation of the uterus in endometritis. Knowledge of the immunological mechanisms observed in cows with endometritis might aid in choosing the correct immunomodulating agent–based adjuvant therapy.     

Reproductive tract defense and disease in postpartum dairy cows

This paper briefly reviews recent data and concepts on the development and mitigation of infection and inflammation in the reproductive tract of dairy cows during the first 2 mo after calving. The incidence of metritis is typically between 10 and 20%, of clinical endometritis or purulent vaginal discharge (PVD) approximately 15%, and of subclinical or cytological endometritis a further 15%. Worse postpartum negative energy balance is associated with more severe or prolonged uterine inflammation. Changes in feed intake, expression of genes for pro-inflammatory cytokines, notably interleukin (IL) 1, IL6 and IL8, circulating concentrations of beta-hydroxybutyrate (BHBA) or nonesterified fatty acids (NEFA), and innate immune function precede both metritis and endometritis by several weeks. Infections with Escherichia coli and Arcanobacterium pyogenes are associated with both metritis and PVD. There are new data to suggest that specific virulence factors in E. coli associated with adherence may be important in metritis and PVD. Cytological endometritis and PVD are overlapping but largely distinct conditions, and there are emerging data that cervicitis exists both concurrent with and separate from endometritis. Much remains to be learned about what initiates and sustains harmful inflammation of the reproductive tract. Such information is necessary to develop effective treatments for the various forms of disease and, more importantly, to develop means to prevent endometritis and cervicitis. In particular, vaccination against specific uterine pathogens and interventions to modulate innate immune response appear to be important avenues for investigation. Presently, commonly recommended best management practices for cows in the transition period are likely to be helpful to mitigate the risk of reproductive disease.     

Effect of partially replacing a barley‐based concentrate with flaxseed‐based products on the rumen bacterial population of lactating Holstein dairy cows

Aims

The effects of partial replacement of a barley‐based concentrate with flaxseed‐based products on the rumen bacterial population of lactating Holstein dairy cows were evaluated.

Methods and Results

Treatments fed were CONT, a normal diet that included barley silage, alfalfa hay and a barley‐based concentrate that contained no flaxseed or faba beans; FLAX, inclusion of a nonextruded flaxseed‐based product containing 55·0% flaxseed, 37·8% field peas and 6·9% alfalfa; EXT, similar to FLAX, but the product was extruded and EXTT, similar to FLAX, but product was extruded and field peas were replaced by high‐tannin faba beans. The rumen bacterial population was evaluated by utilizing 16S rRNA gene sequencing. Most abundant phyla, families and genera were unaffected. However, some taxa were affected; for example, unsaturated fatty acid content was negatively correlated with Clostridiaceae, and tannin content was negatively correlated with BS11 and Paraprevotellaceae.

Conclusions

Predominant rumen bacterial taxa were not affected, but the abundance of some taxa found in lower proportions shifted, possibly due to sensitivity to unsaturated fatty acids or tannins.

Significance and Impact of the Study

Flaxseed‐based products were effective for partially replacing barley‐based concentrate in rations of lactating dairy cows. No negative effects of these products were observed on the abundance of predominant rumen bacterial taxa, with only minor shifts in less abundant bacteria.     

Minimal progesterone concentration required for embryo survival after embryo transfer in lactating Holstein cows

Objectives were to determine progesterone concentration (P4) from days 4 to 28 relative to presumptive estrus necessary for maintenance of pregnancy in lactating Holstein cows. Cows were assigned to the low P4 (LowP4, n = 28) or control (n = 153) treatments. All cows were presynchronized with two injections of PGF_2α (14 d apart) and an ovulation synchronization protocol (11 d later; GnRH on day −10, PGF_2α on day −3; and GnRH on day 0 = presumptive estrus). Cows in the Low P4 treatment received 2 injections of prostaglandin F_2α on days 4 and 5 (day 0 = presumptive estrus) and a new CIDR insert on day 5 that was replaced every 7 d until day 28. Blood was sampled on days −9, −2, 0, 4, 7,14, 21, and 28. Ovaries were examined with ultrasound on days −9, −3, and 7 and cows bearing a corpus luteum ≥20 mm on day 7 received an embryo. On days 0, 4 and 7 P4 did not differ (P ≥ 0.27) but control cows had greater (P < 0.01) P4 on days 14, 21, and 28. Progesterone concentration fold change from day 0 to 7 was not (P = 0.14) affected by treatment, but P4 concentration fold change from day 7 to 14 was (P < 0.01) greater for control cows compared with LowP4 cows. No LowP4 cows became pregnant after embryo transfer, whereas 35.7, 25.5, and 21.4% of control cows were pregnant on day 28, 42, and 63, respectively. Progesterone concentration fold changes from day 0 to 7 (P = 0.03) and from day 7 to 14 (P = 0.05) were associated with pregnancy outcomes on day 63. Among cows that were pregnant on day 63, the minimum P4 concentration fold changes from day 0 to 7 and from day 7 to 14 were 2.71 and 1.48, respectively. Interestingly, cows with P4 concentration <5 ng/mL on day 14 were (P = 0.01) and tended to be (P = 0.07) more likely to lose pregnancy from day 28 to 42 and from day 28 and 63, respectively. Faster rise in P4 concentration during the metestrus and early diestrus are associated with pregnancy establishment following embryo transfer, which suggests that early rise in P4 concentration has an indirect effect on embryo development through modulation of uterine environment and secretion of histotroph. Furthermore, the positive effects of early rise in P4 concentration appear to go beyond the phase of maternal recognition of pregnancy through adhesion and placentation stages.