Lactation Number Research Articles

Surgically managed incarcerated umbilical hernias in calves hold favorable prognosis: a retrospective analysis of 19 cases (2004-2021).

To describe the clinical signs, surgical management, postoperative complications, and outcomes following herniorrhaphy in calves with incarcerated umbilical hernias. This was a retrospective case series. The electronic medical record databases of 2 veterinary teaching hospitals were searched to identify the records of calves that underwent herniorrhaphy for correction of irreducible umbilical hernias between January 1, 2004, and December 31, 2021. Data collected included signalment, medical history, results of clinical examination and laboratory testing, ultrasonographic and surgical findings (incarceration vs strangulation), postoperative complications, and outcome. 19 calves with incarcerated umbilical hernias underwent surgical correction. The incarcerated gastrointestinal tract was identified as the abomasum in 11 calves and jejunum in 8 calves. In 9 calves, the intraoperative identification of strangulation led to 4 intestinal resections and 4 partial abomasectomies, with 1 calf being euthanized intraoperatively. Postoperative complications were reported in 3 calves that underwent intestinal resection. Sixteen calves (84%) survived to discharge and had a median survival time of 1,995 days after surgery. No statistically significant differences were observed between calves with or without gastrointestinal tract strangulation in the short-term survival rate, survival time, or number of lactations after surgery. This study demonstrated that herniorrhaphy for incarcerated umbilical hernias in calves is associated with a favorable prognosis. Postoperative complications are, however, more frequent in calves with strangulated gastrointestinal tract. Surgical intervention for incarcerated umbilical hernias in calves generally yields a positive prognosis, particularly in the absence of gastrointestinal tract strangulation, highlighting the importance of timely diagnosis and treatment.

Variations in hematological parameters of Brazilian Bonsmara cattle at different stages of lactation

The aim of this study was to evaluate the hematological parameters of non-lactating Bonsmara cows and cows at different stages of lactation. A total of 119 cows were used, divided into four groups according to the number of lactations. The hematological evaluations performed were erythrogram and leucogram using automated equipment. The descriptive statistical analysis of the data was performed with a 5% significance level. The experiment followed the ethical principles of animal experimentation (CEUA-UFU protocol 053/2018). Significant differences were found in first lactation animals for erythrocyte count and in second lactation animals for erythrocyte count, hemoglobin, globule volume and platelets. In third lactation animals, significant differences were found for mean corpuscular hemoglobin concentration and platelets. In non-lactating animals, the mean corpuscular hemoglobin concentration showed a significant difference. For the leukogram, significant changes were found in the third lactation animals for rods; and in the concentration of total leukocytes and lymphocytes in the non-lactating animals. This study on the hematology of Bonsmara cattle can serve as a reference base for hematological parameters and as a stimulus for further research on the subject.

The relationship between aflatoxin M1 and immunoglobulin levels in cows' colostrum.

The purpose of the present research was to assess the amounts of aflatoxin M1 (AFM1) and immunoglobulin (IgA, IgG, and IgM) in cow colostrum samples, as well as their relationship. The sampling involved 90 cows (54 Montofon and 36 Simmental) from 15 independent farms. An appropriate number of samples from the total mixed ration (TMR) used in feeding the cows were collected simultaneously with the colostrum samples. AFB1 in feed, AFM1, and immunoglobulin (IgA, IgG, and IgM) levels in colostrum were evaluated using the ELISA method. The AFM1 level in colostrum samples exceeded the maximum allowed values for raw milk. Ig levels were higher in Montofon-breed cows' colostrum than in Simmentals. However, it was determined that neither the breed nor the lactation number significantly affected the colostrum Ig level. It was determined that there was no linear relationship between the number of lactations and immunoglobulin levels or between AFM1 and immunoglobulin levels in colostrum. Similarly, it was determined that there was no linear relationship between the AFB1 level in the feed and the AFM1 level in the colostrum of animals consuming these feeds.

In vitro capsule or biofilm formation of Streptococcus uberis and bacteriological cure of bovine mastitis.

The relationship between the in vitro detected virulence factors biofilm and capsule formation of Streptococcus (S.) uberis isolates of clinical mastitis in dairy cows and the bacteriological cure rate after antibiotic therapy was investigated in order to better understand the importance of these virulence factors for the bacteriological cure rate. A total of 111 clinical mastitis (CM) cases were collected, in which S. uberis was bacteriologically detected. All mastitis cases were treated in accordance with the approval conditions of the antibiotic udder tubes used. Individual cow information including age, number of lactations, current lactation mastitis and antimicrobial treatment received was recorded. The microtiter plate test was used to detect biofilm formation and Anthony capsule staining was used to detect capsular capacity. Statistical analyses were performed to characterize the correlation between in vitro virulence factors and bacteriological cure (BC) rate. 30.5% (n=29) of the S. uberis isolates of bacteriologically cured cases and 34.5% (n=10) of the isolates of bacteriologically non-cured mastitis cases were found to have the ability to produce capsules in vitro. 70.7% (n=58) of the S. uberis isolates from bacteriologically cured mastitis cases had the ability to produce biofilm in vitro, whereas 58.6% (n=17) of the isolates of non-cured mastitis cases showed ability in producing biofilm. No correlation was found between the in vitro ability of S. uberis to form capsules and biofilms and the BC rate after antibiotic treatment of bovine mastitis. The present work has shown that the investigated in vitro virulence factors are not associated with the BC after antibiotic therapy. Further studies on the role of S. uberis virulence factors are needed to complete the missing knowledge on the difficulties in curing S. uberis mastitis. This study is of great clinical relevance since it enhances the understanding of the occurrence of BC in S. uberis mastitis cases. The investigated virulence factors are often addressed as possible reasons for therapy failure, although respective scientific studies are missing.

Влияние возраста первого отела на молочную продуктивность и качество молока

Nowadays, in order to reduce the cost of replacement heifers raising, early insemination and, accordingly, earlier use of cows are practiced in many farms. The purpose of the research is to study the relationship between milk productivity and the age of the first insemination of Holstein heifers under the conditions of OOO Kaluzhskaya Niva (a limited liability company under the laws of Russian Federation) in the Peremyshl district. The experimental groups were formed from cows with completed fourth lactation, taking into account the age of the first fruitful insemination. As the result of the study, it was found out that the optimal insemination index is observed at heifers of the first and second groups upon reaching the age of 12-14 months with a live weight of 337.6-340.9 kg. The shortage of live weight of heifers by the age of 12 months lengthens the time of raising, and reduces the effectiveness of their insemination (group 4 – the multiplicity of insemination is 3.3). The maximum growth rate was observed at heifers of the first group and made 865-931 g/day, which is 6.1-32.1% higher than in heifers of the other groups. When analyzing the dairy productivity of cows, there is a tendency to decrease the level at the second and third lactations, and an increase in the fourth lactation in comparison with the first one. More balanced lactation activity in a number of lactations is observed in cows of the third group (II lactation decreased by 2%, III - decreased by 5%, IV – increased by 17.5%, compared with the first lactation). At the same time, the variation in milk yield in cows of the other groups ranges from -9.2% to +20.6%. The differences in the indicators of the mass fraction of fat and the mass fraction of protein in milk of cows of different groups are not significant. The tendency of decrease of the mass fraction of fat in milk in cows of all groups is noted by the 4th lactation, with increase in the mass fraction of protein. Thus, for the manifestation of high milk productivity and its preservation in a number of lactation, the optimal age for the first insemination of Holstein heifers is 15-16 months.

Social interactions of dairy cows and their association with milk yield and somatic cell count

The social environment experienced by livestock can have implications for their health, welfare, and subsequently, their productivity. Changes in the dairy industry have led to larger herd sizes and altered management of cows, which has impacted their social environment. Studies have shown that mixing of animals can lead to social instability of groups and expansion of herds can lead to high stocking densities resulting in social stress and negative effects on production. Yet few studies have assessed the putative impact of positive cow-cow interactions, such as proximity to preferred herd mates and engaging in grooming, on milk production and udder health. To address this, we used cattle proximity as a proxy for affiliative interactions between cows in three dairy herds in south-west England over one week study periods. We created proximity networks of dairy cows and measured cow-cow associations according to milk yield, somatic cell count (SCC; an indicator of mastitis), parity (number of lactations in the cow’s lifetime), and lactation stage (grouped by days in milk for current lactation). We then assessed associations between social factors and production and health measures (milk yield and SCC). In all three herds, cows interacted more with cows in the same parity, suggesting early social bonding may be evident later in life and that grouping animals in terms of parity might encourage affiliative interactions. Cows did not associate according to milk yield, SCC, or lactation stage. There was no significant association between milk production or SCC and the total time spent in social contact with other cows, the mean time spent with the four closest herd mates, or the number of closest herd mates of the same parity. We suggest that further research on positive social environments for dairy cattle is warranted in the interests of improving welfare and enabling a more robust assessment of the putative effects on production and health parameters

Recipients' and Environmental Factors Affecting the Pregnancy Rates of a Large, Fresh In Vitro Fertilization-Embryo Transfer Program for Dairy Cows in a Commercial Herd in China.

The main objective of this study was to determine the influence of the recipient dairy cows' breed, lactation number, estrus condition, the type, location and volume of the corpus luteum (CL) and the time of year that the embryo transfer (ET) was performed on the pregnancy rates of a large, fresh in vitro fertilization-embryo transfer program for dairy cows in a commercial herd in China. The recipients were from a herd of dairy cows in Ningxia, a province in northwest China, and we statistically analyzed the data of 495 cows from 2021 to 2023. Cumulus oocyte complexes (COCS) were isolated from follicular fluid obtained through ovum pick-up (OPU) and oocytes were incubated 20-22 h for in vitro maturation (IVM). Embryos were obtained after 10-12 h of in vitro fertilization (IVF) and six days of in vitro culture (IVC). Embryos at the morula or blastocyst stage were transferred to randomly chosen recipients (n = 495). The influence of recipients' breed (Holstein or other), recipients' lactation number (heifers or cows), estrus type (natural or synchronized), CL type (homogeneous, CLhom or cavitary, CLcav), CL side (left or right), volume of the CL and season of transfer (spring, autumn or winter) on pregnancy rates were determined. The pregnancy rates were analyzed by binomial logistic regression with IBM SPSS statistics software, version 26. Pregnancy rates after ET to Holstein cows and other breeds were 43.49% and 42.68%, respectively (p > 0.05). Regarding age, pregnancy rates were 45.56% for heifers and 30.77% for cows (p < 0.05). Pregnancy rates following ET during natural and synchronized estrus were 44.41% and 41.5%, respectively (p > 0.05). Pregnancy rates with a left- or right-side CL were 40.18% and 45.65%, respectively (p > 0.05). The pregnancy rates achieved with a CLhom and CLcav were 44.44% and 39.68%, respectively (p < 0.05). The rates obtained in spring, autumn and winter were 49.26%, 46.02% and 34.64%, respectively (p < 0.05). Moreover, it was found that pregnancy rates were higher in recipients with a CL volume measuring greater than 10 cm3 compared with those with a CL volume measuring less than 10 cm3 (p < 0.05). The comparisons showed that recipients' breed, estrus type or side of the CL had no effect, but the recipients' lactation number, ET season and the type and volume of the CL have significant effects on pregnancy rates during ET.

Genetic evaluation of udder health traits in the Spanish Holstein Cows

The aims of this study were to estimate the genetic parameters of clinical mastitis (CM) and somatic cell score (SCS) traits, and to compare the performance of genetic evaluations of CM traits using univariate and bivariate analyses (CM-SCS). Data was edited according to the Udder Health Golden Standard harmonization and then, 6 CM traits and 6 SCS traits were considered, as the result of combining 3 lactation classification (1, 2, ≥ 3) and 2 milking periods (early, late). The linear mixed animal models included the ratio of period at risk as a covariate, herd-year of calving, month of calving, and lactation-age as fixed effects, and the permanent environmental effect for traits of ≥ 3 lactations. Prevalence of CM in early lactation was similar regardless the lactation number (5-6%) and the estimated heritabilities were 0.01. Prevalences in late lactation ranged from 10% to 24% and heritabilities ranged from 0.03 to 0.05. Estimated heritabilities of SCS ranged from 0.06 to 0.16 with univariate analyses. Somatic cell count (therefore its log-transformation SCS) showed higher probability of identify correctly healthy cows than infected cows but there was still up to 36% of healthy cows for CM not detected by SCS. Genetic correlations between CM-SCS traits ranged from 0.36 to 0.95, and SCS in lactation 3 and later did not add extra information to SCS in second lactation for predicting CM. Regarding reliabilities of estimated breeding value (EBV) for CM traits, bivariate CM-SCS analyses led to substantial increases with respect to the single-trait model for sires (7-12% more in first lactation and 16-28% more for second lactation). Sire's rank correlations for CM between univariate and bivariate analyses (0.47-0.92) suggest that discarding sires could be more accurate than selecting candidates for sires of dams. We can conclude that SCS in first lactation could be useful to supplement CM data in first and second lactations to improve udder health genetic evaluation.

The Impact of Varying Pasture Levels on the Metabolomic Profile of Bovine Ruminal Fluid.

A pasture or concentrate-based dietary regime impacts a variety of factors including both ruminal health and function, and consequently milk production and quality. The objective of this study was to examine the effect of feeding differing pasture levels on the metabolite composition of bovine ruminal fluid. Ruminal fluid was obtained from rumen-cannulated spring-calving cows (N = 9, Holstein-Friesian breed, average lactation number = 5) fed one of three diets across a full lactation season. Group 1 (pasture) consumed perennial ryegrass supplemented with 5% concentrates; group 2 received a total mixed ration (TMR) diet; and group 3 received a partial mixed ration (PMR) diet which included pasture and a TMR. Samples were taken at two timepoints: morning and evening. Metabolomic analysis was performed using nuclear magnetic resonance (1H-NMR) spectroscopy. Statistical analysis revealed significant changes across the dietary regimes in both morning and evening samples, with distinct alterations in the metabolite composition of ruminal fluid from pasture-fed cows (FDR-adjusted p-value < 0.05). Acetate and butyrate were significantly higher in samples derived from a pasture-based diet whereas sugar-related metabolites were higher in concentrate-based samples. Furthermore, a distinct diurnal impact on the metabolite profile was evident. This work lays the foundation for understanding the complex interaction between dietary regime and ruminal health.

Effects of Clinical Mastitis on Reproductive Performances in Dairy Cows

The study was undertaken to study the productive and reproductive performances in clinical mastitis (CM) affected and apparently, healthy dairy crossbred cows and to analyze the effects of mastitis considering age, lactation, and severity of mastitis on reproductive performances in crossbred cows. A survey using a questionnaire was done to record different parameters of the cows during the period November 2021 to March 2022. A total of 58 lactating cows included in this study were divided into two groups named mastitis (n=24) and controlled (n=34). Cows of the mastitis groups were divided into subgroups depending on the age, lactation number and severity of mastitis. Prolactin (PRL), progesterone (P4) and estrogen (E2) levels of cows at the time of AI were analyzed. The results showed that cows of the mastitis group had substantially (P&lt;0.01) higher values for Days to first heat detection after parturition (96.16±6.20), Days to first insemination after parturition (105.00±6.64), Days open (140.58±7.40), and number of services per conception (2.33±0.11). The results also indicated that the greatest values were seen in the cows of Sub-group age &gt;8 for Milking Yield (16.21±2.39 Lt), Days to first heat detection after parturition (109.29±13.57), Days to first insemination following parturition (122.14±15.87), and Days open (165.79±16.70), and in cows of Sub-group 7-8 had for the Days of incidence of mastitis following parturition (51.57±12.73). Considering the number of lactations, we observed the highest values of Milking Yield (16.69±2.20 Lt), Days to first heat detection after parturition (108.75±11.58), Days to first insemination following parturition (120.00±13.96), and Days open (160.63±15.20) in cows of Sub-group lactation number &gt;3 and the highest Days of occurrence of mastitis after parturition in cows of Sub-group lactation number 3. Based on the degree of clinical mastitis, it was found that cows of the severe mastitis sub-group had the greatest Milking Yield (24.80±5.40 Liter) at a significant level (P&lt;0.05). This result indicates an association of severe CM with a high yield of milk. Whereas, there was no significant (P&gt;0.05) variation observed in different parameters in terms of reproductive performances in all sub-groups. In addition, significantly (P&lt;0.01) higher prolactin levels (16.10 ±1.17 ng/ml) and low estrogen levels (13.86±0.57 pg/ml) were present in CM-affected cows. This study could help veterinarians in taking strategies to minimize and control the negative effect of clinical mastitis on the reproduction of dairy cows. J. of Sci. and Tech. Res. 5(1): 01-07, 2023

Early prediction of milk yield from Holstein-Friesian cow lactation in Querétaro, Mexico

Objective: To obtain a machine learning (ML) model to predict the milk yield adjusted to 305 d (MY305) from the same lactation period. Design/methodology/approach: A database of test days (TD) was used, made up by 11,892 records of daily milk production from cows with more than 150 days in milk (DIM), from 19 barns in Querétaro, Mexico. The milk production was standardized to specific DIMs (5, 10, 20, 30 and 40) and estimations of MY305 were obtained with these, using ML models. The following were incorporated as explicative variables of the herd: month of birth of the cow, month of start of lactation, number of lactation, number of days for three daily milking events, and the two first linear scores of somatic cells. Results: The best goodness of fit was achieved with ensemble models, obtaining a deviance of 1503584 in the training with 80% of data chosen randomly, while with 20% of the data reserved to evaluate the deviance model it was 1576776. The rate between data observed and predictions of MY305 of the ensemble models had a coefficient of determination of r2 = 0.79 and RMSE of 1256. In the best individual model (deviance of 2281420) of ‘deep learning’ type, the most important variables were daily milk production of 30, 10, 5 and 20 DIM (19.9, 16.6, 16.2 and 12.8%, respectively). Limitations on study/implications: The value of RMSE is high, although the TD databases are generated systematically and usually there are not many barns represented. Findings/conclusions: For the database examined, milk production in the early phase of lactation together with a set of automatic learning models resulted in an adequate prediction of MY305.

The Effects of Breed, Lactation Number, and Lameness on the Behavior, Production, and Reproduction of Lactating Dairy Cows in Central Texas

The Effects of Breed, Lactation Number, and Lameness on the Behavior, Production, and Reproduction of Lactating Dairy Cows in Central Texas

Incidence and recurrence of bovine abortion in dairy cattle from Costa Rica

The reproductive efficiency and milk yield of cows are crucial factors in a dairy farm's profitability. However, abortions can have a negative impact on these factors. While the morbidity of abortion has been estimated in many countries, information on the burden on dairy cattle in tropical conditions is limited, and Costa Rica is a good example. This study aims to assess the incidence and recurrence of bovine abortion in dairy cattle from Costa Rica. The study analysed the morbidity of abortion in Costa Rican dairy herds between 2010 and 2022. The incidence rate (IR) and the recurrence rate (ReR) were calculated per 100 cow-months at risk using data from the Veterinary Automated Management and Production Control Programme (VAMPP). The dataset comprised 1032,457 lactations from 330,265 cows in 1134 specialized dairy herds. Abortions were classified either as early foetal mortality (EFM) or late foetal mortality (LFM). Rates were estimated based on cow breed, lactation number, and ecological zone to which the farm belongs. The IR of general abortion, EFM, and LFM cases were 0.98, 0.41, and 0.57 per 100 cow-months at risk, respectively. No statistically significant differences were found in the IR between cow breed, lactation number, and ecological zone, nor for the trend of abortions over calving years. The first ReR (for cows that had one previous abortion during the lactation) was 0.95, and the second ReR (for cows that had two previous abortions during the lactation) was 1.41 per 100 cow-months at risk. These results suggest that bovine abortions are an important ongoing problem in dairy farms in Costa Rica with potentially detrimental effects on the reproductive and productive performance of cows and may be representative of other specialized tropical dairy systems in Latin America.

Creating a Lactation Model for 305-Day Milk Yield with Different Resampling Techniques (Bagging Mars) in Mars Modeling

The main purpose of this research is to obtain a prediction model for milk yield by using Multivariate Adaptive Regression Splines (MARS) and Bagging MARS algorithms as a non-parametric regression technique. For this purpose, the effects on milk yield of 305 days were investigated by using lactation parameters in dairy cattle. In the study, 9337 lactation milk yield records belonging to 37 animals belonging to the 2022-2023 period were used and the data set was created by randomly ordering the animals. Data on milk yield results were analyzed with MARS and Bagging MARS algorithms. For dairy cattle; it was modeled with explanatory variables such as lactation month (month), service period (SP), last 7 days average milk yield (L7DMMY), animal's first birth age (FP), animal's age (Age), number of lactations (LN).Correlation coefficient (r), coefficient of determination (R2), Adjusted R2, Root of Square Mean Error (RMSE), standard deviation ratio (SD ratio), mean absolute percent error (MAPE), mean absolute for MARS algorithm estimating total average milk yield deviation (MAD) and Akaike Information Criteria (AIC) values are 0.9986, 0.997, 0.977, 0.142, 0.052, 0.2389, 0.086 and -88, respectively. Similar statistics for the Bagging MARS algorithm are 0.754, 0.556, 0.453, 1.8, 0.666, 3.96, 1.47, and 115, respectively. It has been observed that MARS and Bagging MARS algorithms provide correct results according to the goodness of fit statistics. In this study, it was revealed that MARS algorithm gave better results in milk yield modeling of 305-day lactation.

Effects of Parity on Service per Conception, Gestation Length, Milk Yield, Calving Interval, and Calf Birth Weight of Crossbred Dairy Cows

AbstractThe average lactation number for a stable herd dairy cow would be 3.4 and many dairy farmers do not keep dairy cows for extended lactation numbers beyond the 6th lactation number. Thus, there is a limited number of information focused on the later lactation number or parity (6-10) effect on lactation traits. Therefore, this study was conducted to evaluate the effect of lactation number on the number of services per conception, gestation length, lactation milk yield, lactation length, calving interval, and calve weight in crossbred Holstein Friesian cows. The record data at Haramaya University dairy farm was collected and compiled to assess the effects of lactation numbers. Retrospective data records of 1863, 1742, 1280, 1280, 1329, 1170, and 848 data of dairy cows were respectively used for evaluating the number of services per conception, gestation length, lactation length, lactation milk yield, calving interval, and calf birth weight. The study revealed that lactation number significantly affected the total lactation milk yield, lactation length, calving interval, and calf birth weight but it did not affect the number of services per conception and gestation length. Based on this study result, crossbred Holstein Friesian cows could be productive until the 8th lactation number without a significant decrease in the lactation milk yield. Therefore; lactation number should be used as an important trait in the performance of dairy cattle. Further study should be conducted to evaluate the effect of lactation number on other lactation traits such as dry period, days open, and milk composition.Keywords: Birth weight; Calving interval; Gestation; Lactation; Milk yield; Parity

Genetic relationships between behavioral traits and feed efficiency traits in lactating Holstein cows

The evaluation of dairy cow feed efficiency using residual feed intake accounts for known energy sinks. However, behavioral traits may also contribute to the variation in feed efficiency. Our objective was to estimate the heritability and repeatability of behavioral traits and their genetic correlations with feed efficiency and its components in lactating Holstein cows. The first data set consisted of 36,075 daily rumination and lying time records collected using a SMARTBOW ear tag accelerometer (Zoetis, Parsippany, NJ) and 6,371 weekly feed efficiency records of 728 cows from the University of Wisconsin-Madison. The second data set consisted of 59,155 daily activity records, measured as number of steps, recorded by pedometers (AfiAct; S.A.E. Afikim, Kibbutz Afikim, Israel), and 8,626 weekly feed efficiency records of 635 cows from the University of Florida. Feed efficiency and its components included dry matter intake, change in body weight, metabolic body weight, secreted milk energy, and residual feed intake. The statistical models included the fixed effect of cohort, lactation number, and days in milk, and the random effects of animal and permanent environment. Heritability estimates for behavioral traits using daily records were 0.19 ± 0.06 for rumination and activity, and 0.37 ± 0.07 for lying time. Repeatability estimates for behavioral traits using daily data ranged from 0.56 ± 0.02 for activity to 0.62 ± 0.01 for lying time. Both heritability and repeatability estimates were larger when weekly records instead of daily records were used. Rumination and activity had positive genetic correlations with residual feed intake (0.40 ± 0.19 and 0.31 ± 0.22, respectively) while lying time had a negative genetic correlation with this residual feed intake (-0.27 ± 0.11). These results indicate that more efficient cows tend to spend more time lying and less time active. Additionally, less efficient cows tend to eat more and therefore also tend to ruminate longer. Overall, sensor-based behavioral traits are heritable and genetically correlated with feed efficiency and its components and, therefore, they could be used as indicators to identify feed efficient cows within the herd.

District-wide herd sanitation and eradication of intramammary Staphylococcus aureus genotype B infection in dairy herds in Ticino, Switzerland

The present study demonstrates successful herd sanitation and eradication of contagious mastitis caused by Staphylococcus aureus genotype B (S. aureus GTB) in an entire Swiss district (Ticino) including 3,364 dairy cows from 168 farms. Herd sanitation included testing of all cows using a highly GTB specific and sensitive qPCR assay, implementation of related on-farm measures, appropriate antibiotic therapy of GTB-positive cows and culling of therapy-resistant animals, respectively. A treatment index was used as an objective criterion to select GTB-positive cows eligible for culling and replacement payment. 62 herds (37%) were initially GTB-positive with a cow prevalence between 10% and 100% and were submitted to sanitation. Twenty mo after the start of the campaign, all these herds were free from S. aureus GTB, whereby 73% of them were sanitized during the first 7 mo. At the cow level, a total of 343 animals were infected. 50 of them were immediately culled and financially compensated based on their treatment index value. The remaining 293 cows were intramammarily treated with antibiotics either during lactation using the combination of cephalexin-kanamycin or penicillin-gentamicin or at dry-off using cloxacillin. Out of these cows, 275 (93.9%) were treated successfully meaning that their milk was twice GTB-negative by qPCR after therapy. For lactational treatment, control samples were taken ≥10 and ≥20 d after treatment, for dry off treatment ≥14 and ≥24 d after parturition. Neither lactation number nor SCC before treatment of the cow nor the type of therapy were associated with therapeutic cure. Using data of 30 GTB-positive and 71 GTB-negative herds (1855 observations), the impact of GTB sanitation on bulk tank milk SCC (BTSCC) was evaluated applying a linear mixed statistical model. In the year before sanitation, BTSCC was always higher in GTB positive than in GTB negative herds. After the start of the campaign, BTSCC declined rapidly in the herds under GTB sanitation and achieved values that no longer differed statistically from those of GTB-free herds after only 2 mo, remaining very similar for the rest of the campaign. The farmers were very satisfied with the outcome of the campaign as all GTB positive herds could be sanitized rapidly, sanitation was sustainable, and milk quality increased.

Subclinical mastitis in Jersey dairy cows and its effects on productivity and inflammatory markers

This study assessed the effect of subclinical mastitis on the productivity and inflammatory markers in Jersey dairy cows. Blood, milk, and milk yield data were collected from 59 Jersey dairy cows reared under a semi-extensive system. Milk samples were collected from individual collectors and evaluated for their somatic cell count (SCC), lactose (Lact), protein, fat, total and defatted dry extracts (DDE), casein, freezing point, and milk urea nitrogen (MUN) levels. After milking, blood was collected by puncturing the coccygeal arteriovenous complex. In the serum samples, the inflammatory biomarkers paraoxonase-1, albumin, and total plasma protein levels were analyzed using colorimetric methods. Samples of the entire diet provided and pastures were submitted for bromatological analysis. Additionally, the body condition score, number of lactations, milk yield, days of lactation, calving interval, number of inseminations until conception, calving-conception interval, and days of pregnancy were analyzed. The cows were categorized based on their SCC into a subclinical mastitis group (SubG), with SCC levels greater than or equal to 200,000 cells/mL, and a control group (CG), with SCC levels below 200,000 cells/mL. Blood metabolic variables, milk quality, and milk production data were analyzed using multivariate regression, analysis of variance, and logistic regression using the SAS® program. The multivariate regression analysis revealed that several markers, such as Lact, total protein, and casein, influenced milk composition, predicting over 97% of the data. The SubG showed lower concentrations of Lact (4.37 vs. 4.47%; P = 0.0002), MUN (20.55 vs. 23.85 mg/dL; P = 0.02), and DDE (9.24 vs. 9.50%; P = 0.02) compared with the CG; moreover, animals in the SubG had a higher number of lactations compared with those in the CG (4.30 vs. 2.69; P = 0.0039). Cows with a Lact content lower than 4.265% (quartile 25%), compared with those with Lact content greater than 4.565% (quartile 100%), were 52 times more likely to have subclinical mastitis. Jersey dairy cows with subclinical mastitis have lower Lact, urea, and defatted dry extract levels in their milk as well as a higher number of lactations. Therefore, Lact levels in milk serve as a good diagnostic marker of subclinical mastitis in Jersey cows. Subclinical mastitis in Jersey dairy cows did not decrease milk yield nor effect reproductive performance.

Relationship between Milk Yield and Reproductive Parameters on Three Hungarian Dairy Farms.

It is postulated that there is negative correlation between milk yield and reproductive performance. However, some studies definitely doubt this causality. The aim of our study was to investigate the relationship between milk production and fertility on three dairy farms. The production parameter was the milk yield (in kg), and fertility was expressed by the number of inseminations per conception (AI index), as well as by the length of the service period (in days). A total of 13 012 lactations from cows with their first three lactations completed were analysed. The number of inseminations was significantly correlated with the milk yield and with the studied farm (p < 0.0001), but its correlation with the lactation number was not significant (p = 0.9477). A similar relationship was found after evaluating the length of the service period. A multiplicative model showed that a 2000 kg milk increase extended the service period by 9% and increased the AI index by 13%. Thereafter, using quartiles of the cows, the service period of the highest-producing group rose by 41.5 days, and the AI index by almost 1, compared to the lowest quartile. Our results indicate a definitive decline in reproductive indicators parallel to an increase in milk production but did not prove an inevitable correlation.

Does patient sex affect the treatment outcome of immune checkpoint inhibitors? A Danish, observational melanoma study

AimThe objective of this study was to evaluate whether patient biological sex influences treatment outcomes in patients with metastatic melanoma (MM) undergoing first-line immune checkpoint inhibitor (ICI) therapy. MethodsThe Danish Metastatic Melanoma Database (DAMMED) was employed to identify patients who underwent first-line ICI therapy for MM in Denmark from 2013 to 2021. Excluding adjuvant treatment, uveal and mucosal histological subtypes, the study conducted univariable and multivariable analyses to evaluate the influence of patient sex in survival analyses. Further, landmark survival of this real-world national cohort was described for progression free survival (PFS), overall survival (OS) and melanoma-specific survival (MSS). ResultsThe analysis encompassed a cohort of 1378 patients with MM. Compared to male sex, females had significantly improved OS (p = 0.003) when tested in univariable testing. Multivariable analyses, controlling for age, performance status, lactate dehydrogenase level, BRAF status, M-stage, and number of metastatic sites revealed significant favourable outcomes associated with female sex irrespective of the considered survival metrics (pPFS = 0.014, pOS = 0.002, and pMSS = 0.03). The observed five-year OS rates of the entire cohort were 47% and 38%, while melanoma-specific survival were 50% and 45% for female and male, respectively. ConclusionIn this nationwide cohort of patients with MM undergoing first-line ICI treatment females exhibited superior treatment outcomes compared to males. Sex was identified as an independent predictive variable for treatment outcomes, irrespective of the chosen outcome measures considered. Our analyses are not able to conclude whether the differences in outcome is attributable to differences in biology or to treatment strategy.