High somatic cell counts and changes in milk fat and protein contents around insemination are negatively associated with conception in dairy cows

The Influence of Selected Environmental Factors on the Number of Somatic Cells in Cistern and Alveolar Milk of Polish Holstein-Friesian Cows

The aim of the study was to evaluate the influence of the milking phase on somatic cell count (SCC) in milk obtained from the cisternal and alveolar parts of udders of selected Polish Holstein-Friesian cows. The study also assessed the impact of other genetic and environmental factors on SCC variability in cisternal and alveolar milk, including: the individual cow, lactation stage, age of cow, production level, milking speed, fat-to-protein ratio, and milking type. The research included 15 cows of Polish Holstein-Friesian breed at different ages, lactation stages, and with varying daily milk yield. A total of 210 milk observations were conducted, including 105 for 1 min milking and 105 for 8 min milking. The results obtained in the study indicated that milk obtained during two different milking phases exhibited similar SCC levels (F for LOGSCC = 0.79). The average actual SCC in milk produced by 15 cows in 105 observations for 1 min milking was 219,000 cells/mL, while for 8 min milking it was 229,000 cells/mL. The results were inconclusive, suggesting that SCC in cisternal and alveolar milk must be influenced by factors other than the milking phase. The analysis of variance conducted for this purpose provided the basis for stating a highly statistically significant effect of the individual cow (F for LOGSCC = 147.9), lactation stage (F for LOGSCC = 54.64), age of cow (F for LOGSCC = 12.39), daily production level (F for LOGSCC = 34.49), milking speed (F for LOGSCC = 17.56), and fat-to-protein ratio (F for LOGSCC = 22.99) on the variability of characteristics defining SCC in milk. In summary, SCC is characterized by high variability, influenced by a range of environmental and genetic factors such as the individual cow, lactation stage, age of cow, milking speed, and dietary fat-to-protein ratio. The influence of milking phase (1 min or 8 min) and milking type (morning or evening) should be considered inconclusive based on the entire population studied. For half of the cows, SCC in cisternal milk was higher than in alveolar milk, while for the other half, the situation was reversed. Further observations are required to confirm the hypothesis regarding the extent to which cows' immunological response to bacterial infections is concentrated in the cisternal or alveolar part of the udder under national environmental conditions.

Effects of Buffalo Milk and Cow Milk on Lipid Metabolism in Obese Mice Induced by High Fat

The aim of this study was to evaluate the effects of buffalo milk and cow milk on lipid metabolism in obese mice. Milk composition analysis showed fat, protein, and total solid content in buffalo milk was higher than cow milk, while the lactose content of buffalo milk was lower than cow milk. After milk metabolite extraction and LC-MS/MS analysis, differential metabolites were mainly enriched in “linoleic acid metabolism pathways,” “pentose and glucuronate interconversion pathways,” and “metabolism of xenobiotics by cytochrome P450 pathways.” We fed three groups of C57BL/6J mice (n = 6 per group) for 5 weeks: (1) high-fat diet group (HFD group); (2) high-fat diet + buffalo milk group (HBM group); and (3) high-fat diet + cow milk group (HCM group). Our results showed that body weight of mice was significantly decreased in HBM and HCM groups from 1 to 4 weeks compared with the HFD group. The mRNA expression of ACAA2, ACACB, and SLC27A5 genes involved in the lipid metabolism in liver tissue were significantly elevated in HCM group, relatively to HFD and HBM group. In addition, the adipocyte number, size and lipid accumulation in the liver were significantly decreased in HCM group compared with the HFD group by H&E staining and oil red O staining, but was not change in HBM group. The mRNA levels of TNF-α and IL-1β inflammatory genes were significantly increased in HBM group, relatively to HFD and HCM group, which is consistent with results from inflammatory cell infiltration and tissue disruption by colon tissue sections. In conclusion, dietary supplementation of cow milk has beneficial effects on loss of weight and lipid metabolism in obese mice.

The Use of Artificial Neural Networks and a General Discriminant Analysis for Predicting Culling Reasons in Holstein-Friesian Cows Based on First-Lactation Performance Records

The aim of the present study was to verify whether artificial neural networks (ANN) may be an effective tool for predicting the culling reasons in cows based on routinely collected first-lactation records. Data on Holstein-Friesian cows culled in Poland between 2017 and 2018 were used in the present study. A general discriminant analysis (GDA) was applied as a reference method for ANN. Considering all predictive performance measures, ANN were the most effective in predicting the culling of cows due to old age (99.76-99.88% of correctly classified cases). In addition, a very high correct classification rate (99.24-99.98%) was obtained for culling the animals due to reproductive problems. It is significant because infertility is one of the conditions that are the most difficult to eliminate in dairy herds. The correct classification rate for individual culling reasons obtained with GDA (0.00-97.63%) was, in general, lower than that for multilayer perceptrons (MLP). The obtained results indicated that, in order to effectively predict the previously mentioned culling reasons, the following first-lactation parameters should be used: calving age, calving difficulty, and the characteristics of the lactation curve based on Wood's model parameters.

Factors associated with estrous expression and subsequent fertility in lactating dairy cows using automated activity monitoring

The objective of this observational study was to identify factors associated with estrous duration (DU) and intensity measured as the peak of activity (PA) change and subsequent fertility in lactating Holstein cows using a neck-mounted automated activity monitor (Heatime Pro, SCR Engineers Ltd., Netanya, Israel). Ambient temperature and relative humidity were recorded hourly to calculate the temperature-humidity index (THI). A total of 5,933 estrus events from 3,132 cows located on 8 commercial dairy farms in Germany were used for this study. Farms participated in monthly DHIA testing. Pregnancy diagnosis was performed either by transrectal palpation [farm 1: 42 ± 3 d; farm 3: 40 ± 3 d; farms 4 and 8: 38 ± 3 d; farm 5: 43 ± 3 d after artificial insemination (AI)] or transrectal ultrasonography (farms 2, 6, and 7: 30 ± 3 d after AI). Estrous intensity was categorized based on peak activity of estrus into low (35-89 index value), and high (90-100 index value) PA. Overall, 73.5% of estrus events were of high PA. The mean (± standard error of the mean) DU was 14.94 ± 0.06 h. There was a strong correlation between DU and PA (r = 0.67). In the final statistical model, only PA was associated with pregnancy per artificial insemination (P/AI), with 1.35 greater odds of pregnancy for cows with high PA compared with cows with low PA. Increased THI 1 wk before AI was associated with shorter DU, lower PA, and decreased P/AI. A small percentage of cows (4.7%) showed short interestrus intervals (i.e., more than 1 activity peak within 7 d close to the event of estrus), resulting in reduced DU, PA, and P/AI. The change of weighted rumination was associated with DU and PA, as a lower nadir was associated with a greater risk for high PA and long DU. There was no association, however, between the nadir of change of weighted rumination and P/AI. Whereas milk yield and somatic cell count from the DHIA test date before AI were negatively associated with estrous expression, neither milk yield nor somatic cell count was associated with P/AI. Surprisingly, multiparous cows expressed estrus with longer DU (13.15 ± 0.31 h) compared with primiparous cows (12.52 ± 0.32 h), whereas PA did not differ among parities. Pregnancy per AI was greater for primiparous (29.4%) than for multiparous (22.1%) cows. An estrus event with long DU or high PA was more likely later in lactation. Milk fat, milk protein, milk urea nitrogen, and lactose from the DHIA test date closest to AI had no association with estrous expression or P/AI. In conclusion, DU and PA were highly correlated, and cows with high PA were particularly associated with greater odds for pregnancy. A negative association between estrous expression and P/AI was identified for increased THI 1 wk before AI and cows with short interestrus intervals using automated activity monitor.

Inline Reticulorumen pH as an Indicator of Cows Reproduction and Health Status

Our study hypothesis is that the interline registered pH of the cow reticulum can be used as an indicator of health and reproductive status. The main objective of this study was to examine the relationship of pH, using the indicators of the automatic milking system (AMS), with some parameters of cow blood components. The following four main groups were used to classify cow health status: 15-30 d postpartum, 1-34 d after insemination, 35 d after insemination (not pregnant), and 35 d (pregnant). Using the reticulum pH assay, the animals were categorized as pH < 6.22 (5.3% of cows), pH 6.22-6.42 (42.1% of cows), pH 2.6-6.62 (21.1% of cows), and pH > 6.62 (10.5% of cows). Using milking robots, milk yield, fat protein, lactose level, somatic cell count, and electron conductivity were registered. Other parameters assessed included the temperature and pH of the contents of reticulorumens. Assessment of the aforementioned parameters was done using specific smaX-tec boluses. Blood gas parameters were assessed using a blood gas analyzer (EPOC (Siemens Healthcare GmbH, Erlangen, Germany). The study findings indicated that pregnant cows have a higher pH during insemination than that of non-pregnant ones. It was also noted that cows with a low fat/protein ratio, lactose level, and high SCC had low reticulorumen pH. They also had the lowest blood pH. It was also noted that, with the increase of reticulorumen pH, there was an increased level of blood potassium, a high hematocrit, and low sodium and carbon dioxide saturation.

Inflammation: friend or foe of bovine reproduction?

Inflammation is not only the first line of defense of the organism but is also required in many reproductive processes such as ovulation, corpus luteum development, luteolysis, uterine clearance after insemination and post partum. Nevertheless, if excessive or persistent, inflammation can switch from a positive mechanism to a deleterious process, impairing oocyte quality and embryo development. Not only uterine but also non genital inflammatory sites can depreciate reproductive performances, with a carry over effect of 2 to 4 months. Since the metabolic challenges of the peripartum transition period make difficult for the cow to control inflammation, dairy cows are frequently in a pro-inflammatory stage, suggesting that inflammation, rather than infection, is a limiting factor of fertility in modern dairy cows. Within the first week after calving, cows have to mount an intense inflammatory response to the bacterial invasion of the uterine cavity with the challenge of being able to switch it off in no more than 5-6 weeks. The absence of neutrophils on endometrial smear is associated with the highest success rate at insemination. Since a fine tuning – rather than an absence - of inflammation is required along the reproductive cycle, anti-inflammatory drugs do not allow any improvement of pregnancy rate, except in the specific case of embryo transfer. Appropriate management of the transition period (especially nutritional) and in a long term perspective, genetic selection contribute to improve the aptitude of cows to controls the intensity of inflammatory process.

Association of lameness and mastitis with return-to-service oestrus detection in the dairy cow

Oestrus detection is an important part of maintaining efficient reproductive performance in dairy herds. Both lameness and mastitis are common diseases of dairy cows that may impact oestrus detection. A set of data from 28 herds identified as having good recording of clinical mastitis and lameness incidents was used for the study. Logistic regression was used to identify associations between disease episodes within 100 days of insemination and changes in the probability of reinsemination at either 18-24 or 19-26 days after an unsuccessful insemination. Population attributable risk was calculated to understand the impact these diseases may have at a herd level. Lameness 0-28 days after the first insemination of the interval decreased the odds of a reinsemination at an appropriate time by approximately 20 per cent. Clinical mastitis 1-28 days prior to the first insemination of the interval increased the odds of reinsemination at the expected time by approximately 20 per cent. The associations were similar for either interservice interval outcome. Population attributable risk suggested that the effect of these diseases on the probability of reinsemination at the expected time at a population level would likely be extremely small.

Hyperketolactia occurrence before or after artificial insemination is associated with a decreased pregnancy per artificial insemination in dairy cows

The reproductive parameters of dairy cattle have continuously declined worldwide over the last 50 years. Nutritional imbalances are identified as risk factors for this decrease of reproductive performance. The present paper aims to quantify the decrease in the pregnancy per artificial insemination (P/AI) in the case of high milk ketones before and after AI. A total of 388,731 test-day from the Brittany Milk Recording Program in France from 226,429 cow-lactations were provided for this trial. For each test-day, information about lactation characteristics, date of AI, date of the following calving, and acetone and β-hydroxybutyrate (BHB) values were included. Ketones were predicted by Fourier transform mid-infrared spectroscopy using MilkoScan Foss analyzers (Foss, Hillerød, Denmark). Many thresholds were evaluated to define cows with hyperketolactia. Hyperketolactia statuses were then categorized into 1 of 4 possible classes according to the milk ketone dynamics for each AI and each threshold of acetone or BHB values (low-low, high-low, low-high, and high-high) within 20 d before and after AI. Similarly, the dynamics of udder health were characterized by changes in somatic cell counts measured at the same test day as ketone bodies. A logistic regression with a Poisson correction was performed to explain the relationship of P/AI with milk ketones and somatic cell count dynamics. Predicted acetone and BHB ranged from -0.51 to 4.92 mM (mean = 0.08 mM, SD = 0.10 mM) and -0.62 to 5.85 mM (mean = 0.07 mM, SD = 0.1 mM), respectively. Hyperketolactia defined by high acetone levels before AI was not associated with decreased P/AI, but high acetone levels after AI were associated with a >10% reduction in P/AI for all thresholds >0.10 mM. Hyperketolactia, defined by high BHB values before, after, or before and after AI, was associated with a 6 to 14% reduction in P/AI compared with cows with low BHB values. These associations are lower than those reported in previous trials in which blood ketones were used. High ketones in advanced lactation are likely to be the result of various primary disorders (secondary ketosis). Because the present work demonstrated that this situation is considered a risk factor for deteriorated reproductive performance, we suggest that high ketones in early and advanced lactation should be of interest to farm advisors.

Undernutrition modified metabolic responses to intramammary lipopolysaccharide but had limited effects on selected inflammation indicators in early-lactation cows

The objective was to assess effects of experimentally induced undernutrition on responses to an intramammary lipopolysaccharide (LPS) challenge in early-lactation cows. Starting at 24 ± 3 d in milk, multiparous Holstein cows either received a ration containing 48% straw for 96 h to restrict nutrient intake (REST, n = 8) or were allowed ad libitum intake of a lactation diet (CONT, n = 9). After 72 h on diet or after an equivalent period for CONT, 50 µg of LPS (Escherichia coli 0111:B4) was injected into one healthy rear mammary quarter to induce an acute inflammation response. Blood samples were collected weekly until 7 wk of lactation, daily during feed restriction (or control), before and at 1, 2, 4, 6, 10, and 24 h relative to LPS injection. Foremilk quarter samples were collected before and at 4, 6, 10, and 24 h after LPS injection. Dry matter intake, milk yield, energy balance, plasma glucose, nonesterified fatty acids (NEFA), and β-hydroxybutyrate (BHB) concentrations did not differ between CONT and REST immediately before nutrient restriction in REST (least squares means at d -1 were 21.8, 39.0 kg/d, -2.5 MJ/d, and 3.78, 0.415, 0.66 mM, respectively) but were significantly altered at 72 h of nutrient restriction (9.8, 28.3 kg/d, -81.6 MJ/d, and 2.77, 1.672, and 2.98 mM, respectively), when the LPS challenge was performed. The rectal temperature increment from baseline values in response to LPS did not differ, but cortisol increment was greater and cortisol response area under the curve (AUC) tended to be greater [202 vs. 122 (ng/mL) × 10 h] for REST than CONT. No treatment differences were observed in foremilk IL-8, IL-1β, tumor necrosis factor-α, and chemokine (C-X-C motif) ligand 3 concentrations in response to LPS injection. Composite milk somatic cell count per milliliter (6.919 × 10⁶ vs. 1.956 × 10⁶ cells/mL) and total number of somatic cells secreted in milk per day were greater for REST than CONT during the day following LPS. Plasma glucose, urea, and insulin concentrations increased after the LPS challenge, suggesting establishment of insulin resistance and modifications of glucose metabolism to support acute inflammation in both CONT and REST. Nonetheless, nutrient-restricted cows had delayed plasma insulin and glucose responses to LPS, smaller insulin AUC but greater glucose AUC compared with CONT, despite the limited nutrient availability to sustain an inflammation response. Undernutrition altered peripheral metabolic responses to an intramammary LPS challenge but had limited effects on selected indicators of inflammation response in early-lactation cows.