Lower Milk Yield Research Articles

Short Communication: Mammary epithelial cell exfoliation increases as milk yield declines, lactation progresses, and parity increases.

Milk yield (MY) naturally declines after peak lactation. One approach to improving production is to increase lactation persistency, or the length of time a cow maintains lactation. To do so, cows must maintain functional secretory mammary epithelial cells (MEC), which synthesize milk. Some viable MEC are exfoliated from the udder into milk. The objective of this experiment was to identify the magnitude and direction of association between exfoliated MEC and MY, days in milk (DIM), and parity. Our hypothesis was that MY and the quantity of exfoliated MEC were negatively correlated. Therefore, milk from low yielding, late lactation, and primiparous cows would contain more MEC. Thirty-six multiparous and 12 primiparous Holstein cows were sampled once during lactation. A single milk sample was obtained from each cow during a morning milking. Flow cytometry was used to identify milk cell types. Cells were stained with an antibody specific for cluster of differenciation-45 (CD45) to label hematopoietic cells and exclude them from analysis. An antibody against butyrophilin 1A1 (BTN), a protein involved in milk fat secretion, labeled MEC. Nucleated cells were stained with Hoechst dye, and propidium iodide was used to identify dead cells. For statistical analysis, we analyzed the effect of parity, MY, and DIM, and DIM2 on the number and concentration of both total and live exfoliated MEC. Primiparous cows exfoliated fewer MEC and had a lower concentration of MEC in milk than multiparous cows regardless of lactation stage. This could reflect continued mammary growth in first lactation. Cows shed an average of 9.80x107 ± 6.907 MEC with a concentration of 4,582 ± 3,574 cells/mL in one milking. Milk yield was inversely related to concentration of both total and live MEC in milk. Similarly, cows in late lactation, which is associated with MY decline, exfoliated a greater number of MEC into milk. Primiparous cows had a lower milk yield and shed fewer total and live MEC in this study. The relationship of MY and DIM with MEC losses in milk may also contribute to declining MEC number in the mammary gland found in post-peak lactation. Understanding MEC exfoliation regulation could help develop husbandry practices that improve secretory cell retention in the mammary gland and increase lactation persistency.

Successful Control of Mycobacterium avium Subspecies paratuberculosis Infection in a Dairy Herd within a Decade-A Case Study.

This longitudinal case study provides an in-detail report of the process towards the elimination of Mycobacterium avium subsp. paratuberculosis (MAP) from a closed 450-head commercial dairy herd. In parallel, two diagnostic approaches were applied to all cows in annual intervals during 2012-2022: detection of MAP in individual faecal samples by bacteriological cultivation on solid medium and detection of MAP-specific antibodies by ELISA. For each annual sampling, the kappa coefficients for test agreement and the survival rates of MAP-positive and MAP-negative cows were calculated. Applying a multivariable linear regression model revealed a significantly lower fat-corrected 305-day milk yield for MAP-positive cows. The true prevalence of MAP shedders reduced from 24.2% in 2012 to 0.4% in 2019 and during 2020-2022, no MAP shedder was identified. Test agreement was generally low and bacteriological cultivation showed positive results earlier than the ELISA. In the first years of control, the survival of MAP shedders was longer than in the final stage. In conclusion, the elimination of MAP from a dairy herd might be feasible within a decade. Changes in the test agreement must be considered. Timely removal of MAP shedders, hygienic calf rearing, and colostrum supply are key for successful control.

Effect of Calving Season on Productive Performance of Dairy Cows

The aim of the present research was to study the influence of the calving season in conditions of the upcoming climate changes on the productive traits of dairy cows in Bulgaria. The study was conducted on a cattle farm with a capacity of 500 dairy cows, which were loose-housed in open free-stall barns (shed-type). In the research, 286 lactations of 199 Holstein cattle from the studied farm were included. The cows with the highest average milk yield for lactation—8522.2 kg—calved in the spring, while the cows with the lowest milk yield—8082.7 kg—calved in the summer. Cows that calved in the spring had the highest maximum daily milk yield (lactation peak)—38 kg—whereas cows that calved in the summer had the lowest—35.7 kg. Regarding the composition indicators of milk, fat, and protein content, no significant effect of the calving season was found, but there was a tendency for the lowest values for the percentage of fat in milk to be reported for cows that calved in the summer—3.68%—and the highest for those calved in the spring—3.71%. Regarding the percentage of protein in the milk, the lowest values were observed for cows that calved in autumn—3.19%—and the highest for cows that calved in summer—3.27%.

Using of Nanoparticles in treating of Hydatid Disease in Domestic Animals

The parasite Echinococcus granulosus is the cause of unilocular hydatid disease, which is a serious health risk to people and domestic animals worldwide. Livestock with hydatid disease suffers substantial financial losses due to the slaughterhouse's disapproval of the diseased animal parts, productivity losses (such as lowered live weight gain, milk yield, reproductive rates, and hide and skin value), and expenses related to caring for both humans and animals. Because of the parasite's complex life cycle and the difficulties associated with traditional treatment techniques, new strategies are needed to handle this crippling illness more successfully. In the treatment of hydatid illness, nanomedicine and nanoparticles have shown great promise, providing new approaches to medication distribution, focused therapy, diagnosis, and control measures. The possible roles and applications of nanomedicine and nanoparticles in treating hydatid illness in domestic animals are reviewed in this article. Owing to their distinct physicochemical characteristics at the nanoscale, nanoparticles enable tailored medication administration, enhancing anthelmintic agent potency while reducing systemic side effects. Therapeutic drugs like praziquantel or albendazole can be encapsulated in these nanoparticles, allowing for improved permeability and retention at the location of the parasite cysts. Additionally, imaging agents and diagnostic instruments at the nanoscale enable. Additionally, nanotechnology offers avenues for developing innovative control measures, including environmental disinfection and targeted delivery of parasiticides. Collaborative efforts between researchers, veterinarians, and experts in nanotechnology are crucial to harnessing the full potential of nanoparticles and nanomedicine in effectively managing the infection in domestic animals.

Associations of lameness with milk composition, fatty acid profile, and milk coagulation properties in mid-lactation high-yielding Holstein cows

Lameness, an animal welfare and profitability related problem in dairy industry, was evaluated on 126 multiparous Estonian Holstein cows on a 5-point scale; score three or above indicated lameness. Milk samples of the cows were analysed for basic composition, content of mineral elements, fatty acid (FA) profile and coagulation properties (MCP). Lame cows had lower milk yield and a lower milk protein and milk fat yield compared to non-lame cows. MCP and content of mineral elements were not affected by lameness. The concentrations of most individual milk FA, their groups formed by chain length, degree of saturation or by origin were not affected by the lameness. Lameness was associated with a higher concentration of odd- and branched-chain fatty acids and C18:0. Milk from lame cows is suitable for consumers as lameness did not impair nutritional value nor MCP of the milk.

Rapid authenticity assessment of PGI Hongyuan yak milk based on SICRIT-QTOF MS

Hongyuan (HY) yaks live in a pollution-free environment, making HY yak milk a green food, but their short milk production period and low milk yield make yak milk precious and expensive. The phenomenon of counterfeiting HY yak milk with ordinary milk from other origins has already occurred, so the authenticity assessment of HY yak milk is necessary. This study developed a rapid soft ionisation by chemical reaction in transfer quadrupole time-of-flight mass spectrometry (SICRIT-QTOF MS) for HY yak milk differences assessment. Principal component analysis and orthogonal least squares discriminant analysis showed differences between HY milk and the other three origins. Twenty-eight differential compounds were screened out by variable importance in projection, fold change, P-value, and database matching. Furthermore, six characteristic compounds (proline, 2-hydroxy-3-methylbutyric acid, and l-isoleucine, etc.) of HY samples were putatively identified. The study demonstrated that SICRIT-QTOF MS has great potential for rapidly distinguishing the milk origin.

Soybean Isoflavones Ameliorates Lactation Performance in Postpartum Mice by Alleviating Oxidative Stress and Regulating Gut Microflora.

Postpartum dysgalactiae syndrome (PPDS) is one of the key issues affecting breastfeeding, usually occurring as breast swelling, a low milk yield, and at length a stop of breast milk secretion. Therefore, there is a need to investigate the effectiveness of Traditional Chinese Medicine (TCM) diet therapy in treating or preventing PPDS. This study aims to analyze the effect of soybean isoflavone (SIF), a natural estrogen found in plants, on postpartum lactation performance in mice and to evaluate its potential as a treatment for PPDS. Adult female BALB/c mice at 8 weeks of age (25 ± 3g) are randomly divided into four groups fed with different levels of SIF and a normal diet for 14 days. SIF (0, 50, 100, 200mg kg-1 BW) is provided via intra-gastric route to the experimental mice. Using a high-throughput sequencing of microbial diversity and mammary gland metabolites, it is found that SIF-treated mice potentially show an improved milk performance via enhanced antioxidant capacity and altered gut microbiota. SIF from plant sources at a high dosage promotes the lactation in normal postpartum mice.

INFLUENCE OF PARATYPIC FACTORS ON THE FERTILITY OF DAIRY COWS AND REPLACEMENT HEIFERS

The results of researching the influence of the season, air temperature, age, stage of lactation, insemination number and daily milk yield on the fertilization of heifers and cows under different housing technologies are presented. It was established that the best fertilization was demonstrated by heifers kept in tethered housing at PE Agroprogres. Nevertheless, the fertilization rate of cows among the farms under study was the highest under free housing (p<0.001). By months of the year, in general, on all farms, a trend of a greater number of inseminations of heifers was observed in spring and summer, although no clear dependence was established. The share of fertile inseminations of heifers of PE Agroprogress varied from 56% in October to 92% in June. Fertilization of heifers at SE EFs named after Dekabrists and Kutuzivka had less variability: from 47% in February to 70% in May in the first farm and from 46% in May to 60% in July in the second farm, respectively. At PE Agroprogres and SE EF named after Dekabrists, there was a tendency to increase the fertilization of heifers at the air temperature above 20 ºС. Cows of PE Agroprogres and SE EF named after Dekabrists had the lowest fertilization rate at temperatures below -10 ºC. There was also a trend of its increase with an increase in air temperature above 20 ºC. It was established that at PE Agroprogres (tethered housing) a clear trend of increasing the fertility of cows was observed during the period of summer open air housing, at SE RF named after Dekabrists this trend is almost imperceptible, and the opposite dependence has been established at SE EF Kutuzivka (year-round free housing keeping with feeding on walking platforms). At all studied farms, there was a clear tendency in decrease of the fertilization of cows during the period of high milk productivity. Cows of PE Agroprogres and SE EF Kutuzivka with a daily milk yield of more than 40 kg of milk were fertilized worse by 1-4% (р<0.1) and 5-6% (р<0.001) than animals with a lower milk yield. Cows of the SE EF named after Dekabrists with a daily milk yield of more than 30 kg also had 8-9% (p<0.001) worse fertilization compared to animals with lower productivity. At all studied farms, the highest percentage of fertilization was characterized by heifers at their first insemination, and among cows were animals of the first and second calving. According to all inseminations, the average day of lactation of cows with their artificial insemination was 38-54 days longer at SE EF named after Dekabrists in comparison with PE Agroprogres and SE EF Kutuzivka (p<0.001). The share of fertilized cows during the breeding period up to 90 days after calving was lower by 6% At PE Agroprogres, and by 9% at SE EF named after Dekabrists, and by 6% at SE EF Kutuzivka than in the mid-lactation period (91-180 days) (р<0.001).

ОЦІНКА СТАНУ РОЗВИТКУ МОЛОКОПРОДУКТОВОГО ПІДКОМПЛЕКСУ ЛЬВІВСЬКОЇ ОБЛАСТІ

The article defines the essence and structure of the dairy subcomplex as an important component of the agro-industrial complex of Ukraine, focusing on changes in its localization with the outbreak of full-scale military operations. The results of the functioning of its main sectors: cattle breeding and production of dairy raw materials, milk processing, export-import commodity operations with dairy products and the sphere of consumption are investigated. It is found that Lviv region, with its considerable potential, does not show good results in the domestic market of raw milk, but due to its territorial remoteness from the area of direct hostilities, it has to some extent strengthened its competitive position in this market. There are significant differences in the structure of raw milk production in the region compared to the national figures, and the same disproportions are typical for foreign trade operations with dairy products. At the same time, there are a significant number of milk processing enterprises operating in the region, both local, interregional and national. The analysis of the situation showed that over the past five years, there have been steady deterioration trends in almost all sectors of the dairy subcomplex in Lviv region. These include high costs of keeping livestock, reduced livestock numbers (especially in households), lower milk yields, difficulty ensuring high quality raw milk and sufficient quantities in private households, unfavourable pricing policy on the foreign dairy market, low solvency of the population, negative demographic changes, and a difficult security situation due to the ongoing military operations in the country, a serious shortage of energy resources, which makes it difficult or even impossible to ensure the proper quality of dairy products in the supply chain. To support domestic dairy producers in the region, programs are being implemented to support farming and small manufacturing businesses, numerous grants are being provided, and production cooperation is taking place with the involvement of foreign private and public investment, which is yielding positive results. Also, the dairy industry in Lviv region actively promotes its products in the retail market, which ensures high ratings throughout the country, and is engaged in both meeting the needs of defenders and their social support.

Identifying cows at risk of subclinical ketosis as part of the milk recording of dairy cattle in Poland in 2014-2022

In 2013, the Polish Federation of Cattle Breeders and Dairy Farmers introduced a new service – identifying cows in a state of subclinical ketosis (SK). Based on the content of ketone bodies in milk, i.e. β-hydroxybutyrate and acetone determined in a milk sample taken on the day of the trial milking, cows that were probably in the SK state on the test day are identified using a logistic regression model. Such cows are indicated to breeders in the reports from milk recording. The aim of the study was to analyze the incidence of SK in the recorded population. During 10 years of SK monitoring, the incidence of SK in cows decreased with each subsequent year. SK occurred more often in cows with lower milk yield and in smaller herds. The results indicate a constant improvement in the health situation of recorded cows in Poland, in the context of the incidence of SK.

Effects of parity, calving season, and previous lactation's milk yield on fertility of dairy cows on a commercial farm.

This study investigated the effects of parity, season, and the previous lactation's milk yield on fertility in dairy cows. A total of 5,514 calving records for Holstein cows that calved between 2016 and 2018 on a single large dairy farm in Japan were used for analysis. The proportion of cows that get pregnant by 360 days after calving was defined as the percentage of all cows eligible for breeding that became pregnant. In the all-cow model, pregnancy probability associated with both parity and calving season (p < 0.05). Pregnancy probability decreased with an increase in parity, with hazard ratios (HRs) of 1.75 (1.58-1.94) for parity 1, 1.25 (1.13-1.39) for parity 2, 1.15 (1.04-1.29) for parity 3, and 1.13 (1.00-1.27) for parity 4, relative to parity ≥5. In terms of calving season, the lowest pregnancy probability was found in spring, and the HRs relative to spring were 1.16 (1.07-1.26) for summer, 1.35 (1.24-1.47) for autumn, and 1.17 (1.07-1.27) for winter. In the multiparous-cow model, pregnancy probability associated with the previous lactation's milk yield (p < 0.05), but not with parity or calving season. Cows with high and middle previous milk yields had lower pregnancy probabilities than those with low milk yields.

Reproductive and productive traits of cows of Holstein breed depending on the level of inbreeding

Inbreeding is one of the main criteria in programs for the conservation and use of genetic resources, and it can be used to control genetic processes in populations of farm animals. The use of inbreeding involves the production and consolidation of rare genotypes, which determine the outstanding quality of animals. The purpose of the work was to determine the reproductive and productive traits of cows of Holstein breed depending on the level of inbreeding. The research was carried out in the pedigree farm in the Kaluga region. The research of the reproductive ability of first-calf heifers obtained through inbreeding and outbreeding were shown significant differences in the duration of the calving interval. So, cows obtained through the remote inbreeding had the lowest duration calving interval (385.4 days) and their herdmates from outbreding had the longest calving interval (404,5 days), the difference was 19.1 days (p&lt;0.05) or 5.0%. Cows from remote inbreeding had the shorter calving interval than their herdmates from moderate inbreeding by 15.9 days (p&lt;0.05) or 4.1%. It was found that higher milk yields for 305 days of the first lactation had cows obtained through remote inbreeding (6413.1 kg), and low milk yields of milk were obtained from first-calf heifers from moderate inbreeding (5634.8 kg), the difference was 778.3 kg (p&lt;0.05) or 9.0%. They also surpassed the milk yield of their herdmates obtained from outbreeding by 266.6 kg (p&lt;0.05) or 4.3%. First-calf heifers obtained through moderate inbreeding were inferior in milk yield to herdmates from outbreeding by 511.7 kg or 9.1% (p&lt;0.05).

Choice of metrics matters—Future scenarios on milk and beef production in Norway using an LCA approach

The consumption of dairy and beef products is expected to increase globally in the future, and at the same time, food must be produced in a more sustainable way, including reduced greenhouse gas (GHG) emissions, avoided feed-food competition, and reduced biodiversity loss. The purpose of the study was to a) provide an overall life cycle assessment (LCA) of these impacts for various future milk and beef production systems in Norway and b) determine how the choice of metrics for climate change affects the results. System boundaries were from cradle to farm gate and the temporal boundary was 2017 with future scenarios for 2040. The actual production and consumption in Norway in 2017 was used as a baseline (BL), and the sustainability of future Norwegian domestic production of milk and beef was assessed through three scenarios for 2040: 1) a trend yield scenario (TrendY) based on an expected increase in milk yield following the present trend, 2) a high yield scenario (HighY) with higher increase in the milk yield per cow per year than the trend, and 3) a low yield scenario (LowY) where the milk yield per cow per year was adjusted for covering the domestic demand for beef solely from dual-purpose production and no domestic specialized beef production. The beef production per dual-purpose cow was kept constant and the remaining domestic demand in scenario 1 and 2 were covered by specialized beef production. Climate change was assessed using both a GWP100 and a GWP* approach. The HighY scenario had the lowest impact on climate change using GWP100, but when taking the different behaviors of short- and long-term climate pollutants into account (GWP*), the ranking of the future scenarios changed and favored LowY. The potential biodiversity loss was lower for the LowY scenario because the proportion of concentrates in the dairy cow ration was decreased due to lower milk yield. Similarly, the feed-food competition was lower (land use ratio < 1) for the LowY. The results of our study suggest that the choice of metric for GWP and time frame highly affects the results and conclusions and strategies for climate smart and sustainable livestock production should therefore be made with caution.

Potential for quantifying general environmental resilience of dairy cattle in sub-Saharan Africa using deviations in milk yield.

Introduction: Genetic improvement of general resilience of dairy cattle is deemed as a part of the solution to low dairy productivity and poor cattle adaptability in sub-Saharan Africa (SSA). While indicators of general resilience have been proposed and evaluated in other regions, their applicability in SSA remains unexplored. This study sought to test the viability of utilizing log-transformed variance (LnVar), autocorrelation (rauto), and skewness (Skew) of deviations in milk yield as indicators of general resilience of dairy cows performing in the tropical environment of Kenya. Methods: Test-day milk yield records of 2,670 first-parity cows performing in three distinct agroecological zones of Kenya were used. To predict expected milk yield, quantile regression was used to model lactation curve for each cow. Subsequently, resilience indicators were defined based on actual and standardized deviations of observed milk yield from the expected milk yield. The genetic parameters of these indicators were estimated, and their associations with longevity and average test-day milk yield were examined. Results: All indicators were heritable except skewness of actual and standardized deviation. The log-transformed variance of actual (LnVar1) and standardized (LnVar2) deviations had the highest heritabilities of 0.19 ± 0.04 and 0.17 ± 0.04, respectively. Auto-correlation of actual (rauto1) and standardized (rauto2) deviations had heritabilities of 0.05 ± 0.03 and 0.07 ± 0.03, respectively. Weak to moderate genetic correlations were observed among resilience indicators. Both rauto and Skew indicators had negligible genetic correlations with both longevity and average test-day milk yield. LnVar1 and LnVar2 were genetically associated with better longevity (rg = -0.47 ± 0.26 and -0.49 ± 0.26, respectively). Whereas LnVar1 suggested that resilient animals produce lower average test-day milk yield, LnVar2 revealed a genetic association between resilience and higher average test-day milk yield. Discussion: Log transformed variance of deviations in milk yield holds a significant potential as a robust resilience indicator for dairy animals performing in SSA. Moreover, standardized as opposed to actual deviations should be employed in defining resilience indicators because the resultant indicator does not inaccurately infer that low-producing animals are inherently resilient. This study offers an opportunity for enhancing the productivity of dairy cattle performing in SSA through selective breeding for resilience to environmental stressors.

Whole-genome resequencing reveals candidate genes associated with milk production trait in Guanzhong dairy goats.

Milk production is one of the most important economic utility of goats. Guanzhong dairy goat is a local dairy goat in Shaanxi Province of China and has high milk yield and quality. However, there are relatively few studies on molecular markers of milk production traits in Guanzhong dairy goats. In this study, we sequenced the whole genomes of 20 Guanzhong dairy goats, 10 of which had high milk yield (HM) and 10 of which had low milk yield (LM). We detected candidate signatures of selection in HM goats using Fst and π-ratio statistics and identified several candidate genes including ANPEP, ADRA1A and PRKG1 associated with milk production. Our results provide the basis for molecular breeding of milk production traits in Guanzhong dairy goats.

Effect of Acute and Cumulative Stress on Gene Expression in Mammary Tissue and Their Interactions with Physiological Responses and Milk Yield in Saanen Goats

This study addresses the hypothesis that different acute stressors can cumulatively decrease milk yield. In fact, in a time of global warming, the impact of environmental stress and farm management practices on milk production remains unclear. In this context, our objective was to investigate the effect of acute and cumulative stress on gene expression in mammary tissue and their interactions with physiological responses and milk yield in Saanen goats. Thirty lactating goats were subjected to two treatments: (1) control (CT), in which goats were maintained following a habitual routine under comfort conditions; (2) stress (ST), in which the goats were subjected to different types of environmental stress: heat stress, adrenocorticotropic hormone administration, hoof care management, and exposure to rain. These stressors were performed sequentially, with one stress per day on four consecutive lactation days, to evaluate their effect on milk quality and milk yield. Our results showed that compared to CT goats, cumulative stress increased the gene expression of glucocorticoid receptor (GR), interferon-gamma (IFN-γ), superoxide dismutase (SOD), and catalase (CAT) in mammary tissue, which are indicators of cortisol action, inflammatory response, and antioxidant enzymes. Furthermore, the acute challenges imposed on ST goats changed their rectal temperature and respiratory frequency and increased cortisol, glucose, cholesterol, triglycerides, and high-density lipoprotein release in plasma when compared to CT goats. Although these physiological and metabolic responses restore homeostasis, ST goats showed lower milk yield and higher somatic cell count in milk than CT goats. In conclusion, the results confirmed our initial hypothesis that different acute stressors cumulatively decrease the milk yield in Saanen goats.

DNA methylation of GDF-9 and GHR genes as epigenetic regulator of milk production in Egyptian Zaraibi goat

BackgroundDNA methylation is an epigenetic mechanism that takes place at gene promoters and a potent epigenetic marker to regulate gene expression.ObjectiveThe study aimed to improve the milk production of Zaraibi goats by addressing the methylation pattern of two milk production-related genes: the growth hormone receptor (GHR) and the growth differentiation factor-9 (GDF-9).Methods54 and 46 samples of low and high milk yield groups, respectively, were collected. Detection of methylation was assessed in two CpG islands in the GDF-9 promoter via methylation-specific primer assay (MSP) and in one CpG island across the GHR promoter using combined bisulfite restriction analysis (COBRA).ResultsA positive correlation between the methylation pattern of GDF-9 and GHR and their expression levels was reported. Breeding season was significantly effective on both peak milk yield (PMY) and total milk yield (TMY), where March reported a higher significant difference in PMY than November. Whereas single birth was highly significant on TMY than multiple births. The 3rd and 4th parities reported the highest significant difference in PMY, while the 4th parity was the most effective one on TMY.ConclusionThese results may help improve the farm animals' milk productive efficiency and develop prospective epigenetic markers to improve milk yield by epigenetic marker-assisted selection (eMAS) in goat breeding programs.

Reproduction and Productivity in Dairy Cattle after Abortions Both Related and Unrelated to Coxiella burnetii.

C. burnetii is a widespread pathogen, causing abortions and reproductive disorders in ruminants. The study aimed to evaluate animal reproductive capacity and productivity after abortion, related and unrelated to C. burnetii. We compared data about the abortion time, the outcome of the animals after an abortion, further reproduction, and productivity for C. burnetii-positive (n = 148) and C. burnetii-negative (n = 149) aborted dairy cows and heifers. C. burnetii-positive animals had a positive serological response or presence of C. burnetii DNA at the time of abortion. C. burnetii-positive animals had a significantly higher number of lactations at the time of abortion. However, in the other indicators, we observed no significant differences between the groups. Comparing indicators of all the aborted animals, we found that if animals started a new lactation after abortion, they had a significantly lower milk yield, lower fat, protein, and somatic cell counts (SCCs) in milk during the standard lactation for both primiparous and multiparous cows compared to herd averages in each group. Lower SCCs can be due to animals with a high SCC being culled earlier. We found an economic disadvantage to aborting, not only because of the loss of offspring, but also because of the high culling rate and lower productivity in both primiparous and multiparous cows.

Effect of 2 dosages of prepartum cholecalciferol injection on blood minerals, vitamin D metabolites, and milk production in multiparous dairy cows: A randomized clinical trial

The objective of the present study was to evaluate the effect of 2 dosages of prepartum cholecalciferol injection on blood minerals, vitamin D metabolites, and milk production. Cows entering their second or greater lactation (n = 158) were randomly assigned to a control group (CON) or one of 2 treatment groups receiving either 6 × 106 IU (6VitD) or 12 × 106 IU (12VitD) cholecalciferol intramuscularly on d 275 ± 1.2 (SD) of gestation. Concentrations of serum total Ca (tCa), phosphate, and Mg were determined on 1, 2, 3, 5, 7, and 10 d in milk (DIM). For a subsample of 30 cows entering the third lactation (n = 10/group), these samples were analyzed for cholecalciferol, 25-hydroxycholecalciferol (25-OHD3), and 24,25-dihydroxycholecalciferol (24,25-[OH]2D3). In these cows, we also determined 1,25-dihydroxycholecalciferol (1,25-[OH]2D3), the biologically most active metabolite, on 1, 2, 3, and 5 DIM. Repeated measures ANOVA was performed to evaluate the effect of different dosages of cholecalciferol on blood minerals, vitamin D metabolites, and milk yield over the first 5 test days after calving. Binary outcomes such as retained placenta and metritis were analyzed using a chi-squared test. Although the 12VitD treatment increased tCa concentrations on 1, 2, and 3 DIM compared with CON, administration of 6VitD increased tCa concentrations only on 1 DIM. Compared with CON cows and 6VitD cows, 12VitD cows had greater serum phosphate concentration during the first 10 DIM. Furthermore, 6VitD cows had greater serum phosphate concentrations compared with CON cows. On the contrary, 12VitD cows had lower serum Mg concentrations during the first 10 DIM compared with CON and 6VitD cows. Cholecalciferol was increased by the treatment and decreased quickly until 10 DIM. In respect to 25-OHD3, the 6VitD treatment resulted in a 4.1-fold increase in comparison to the CON group, while a 6.5-fold increase was observed in 12VitD animals. The vitamin D metabolite 24,25-(OH)2D3 increased linearly with 25-OHD3 serum levels, resulting in the highest concentrations in the 12VitD group. An increase of 1,25-(OH)2D3 until 3 DIM was observed in all cows. However, this rise was most pronounced in the CON group. The incidence of retained placenta was 1.9%, 11.5%, and 29.6%, and that of metritis was 11.5%, 15.4%, and 31.5% for CON, 6VitD, and 12VitD cows, respectively. Although none of the treated cows exerted clinical signs of hypocalcemia, one cow in CON incurred clinical hypocalcemia. Cows of the 12VitD group had a lower milk yield over the first 5 monthly test days compared with the control and 6VitD group (42.2 ± 0.5, 42.0, ± 0.5 and 40.7 ± 0.5 kg for control cows, 6VitD cows and 12VitD cows, respectively). Although no negative side effects were observed in 6VitD cows, we do not recommend the general application of 6 × 106 IU cholecalciferol before calving as positive effects on calcium homeostasis were marginal and restricted to the first DIM. The present findings confirm that the application of 12 × 106 IU cholecalciferol negatively affected milk production on this farm.

Incomplete milking before drying off does not impair the udder health of cows infected with minor pathogens.

When implementing the transition from regular milk production to the dry period, drying off is mostly conducted simply by abrupt cessation of milking. Efforts to reduce milk synthesis before cessation of milking aim to reduce stress in cows as well as to lower the risk of mastitis. A previous study demonstrated that incomplete milking during the last ten days of lactation gradually reduced the milk yield of healthy, high-yielding cows. However, a reduction period of ten days might be too long for cows with lower yields. Therefore, a follow-up study was conducted on an organic dairy research farm with a lower average milk yield. We investigated whether automated incomplete milking can reduce milk synthesis within one week without impairing the health status of udder quarters infected with minor pathogens. Before drying off, 15 German-Holstein cows with 58 lactating quarters, 21 of which were infected with minor pathogens (coagulase-negative Staphylococci (CNS) and Corynebacterium bovis), were milked twice daily using the software module AutoDry (GEA Farm Technologies) with the 5%-step-down-per-day-program. The level of udder emptying was gradually reduced over 8-10 milkings beginning at a mean milk yield of 17.2 ± 4.4 kg d-1. During the last three milkings before drying off, milking clusters were automatically removed when a milk flow rate of 0.3 kg min-1 was reached. Quarter fore-milk samples were collected at two time points (14 d before and at the date of the last milking, ie drying off) and were analysed for mastitis pathogens and somatic cell count. The gradual reduced emptying of the udder induced a clear decline in milk yield by 0.8 ± 0.3 kg d-1. Within the reduction period, the somatic cell count of quarter foremilk did not change regardless of the infection status. Furthermore, no cow suffered from clinical mastitis. Thus, a reduction in milk synthesis could be achieved within less than one week before drying off without any impairment in udder health of cows, even when infected with minor mastitis pathogens.