Large Commercial Dairy Farm Research Articles

Produtividade vs. área

The objective of this study was to analyze the development dynamic of the Uruguayan dairy farms in the last decade integrating country, experimental and commercial databases. A large commercial dairy farm database was segmented into four groups according to productivity and growth rate (PGR) during the fiscal years 2015/2016 to 2021/2022. Productivity growth rate was calculated as: PGR = (P2122/P1516)1/6-1, where: P2122 = productivity fiscal year 2021/22, and P1516 = productivity fiscal year 2015/2016. The PGR groups were defined as: negative (NPGR; PGR < 0% per year), low (LPGR; 0 ≤ PGR < 3%), medium (MPGR; 3 ≤ PGR ≤ 6%) and high productivity growth rate (HPGR; PGR ≥ 6%). A mixed model was used to evaluate productivity slope heterogeneity with fiscal year as a continuous variable, PGR group as categorical and their interaction. Farms that were able to increase productivity (M and H PGR) had higher mean productivity, pasture DMI and margin over feed cost vs. the less dynamic systems (N and L PGR). Larger changes in productivity (+64 and +27% for H and M PGR, respectively) were likely primarily due to changes in stocking rate (+20 to 30%) and in individual cow milk production (+10 to 20%). Production systems that increased productivity relied on increasing stocking rate and individual milk production based on more home-grown forage consumption. However, higher PGR was linked to lower initial values of productivity, which suggests decreasing returns as the dairy farms reached higher milk yields and forage DMI.

Virulence factors, antimicrobial resistance and phylogeny of bovine mastitis-associated Streptococcus dysgalactiae.

We carried out a thorough genetic evaluation of Streptococcus dysgalactiae isolated from clinical bovine mastitis cases and performed a phylogenetic analysis to represent the evolutionary relationship between S. dysgalactiae sequences. A total of 35 S. dysgalactiae strains were isolated from cases of clinical mastitis identified at a large commercial dairy farm located near Ithaca, New York. Whole-genome sequencing identified twenty-six antibiotic resistance genes, four of which were acquired genes, in addition to fifty virulence genes. Multi-locus sequence typing detected three new sequence types (STs). We conclude that a high proportion of this microorganism carries multiple virulence determinants and resistance genes, and that this indicates its potential to cause mastitis. Eight different STs were identified, of which ST453 (n = 17) was the most prevalent and ST714, ST715, ST716 were novel STs.

Effects of prepartum supplementation of β-carotene on colostrum and calves.

Little is known about transfer of dietary β-carotene into colostrum, its absorption by the calf, and its effects on retinol and α-tocopherol in the calf when the dam's dietary vitamin A is adequate. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period on the colostrum and calf. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were blocked by calving data, parity, and previous production, and then randomly assigned to either control or β-carotene (BC) treatments. While locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, DSM Nutritional Products, 8 g/d; provided 800 mg β-carotene) or carrier from 21 d before expected calving until calving. Colostrum was collected within 2 h of parturition. Calf blood samples were obtained within 2 h of birth before receiving the dam's colostrum, at 24 h after birth, and at 7 d and 60 d of age. Blood serum was analyzed for β-carotene, retinol, α-tocopherol, and other metabolites and enzymes. Colostrum was analyzed for β-carotene, retinol, α-tocopherol, colorimetry profile, and milk components. Data were analyzed using mixed-effects models in SAS (SAS Institute Inc.). Calf serum β-carotene data were analyzed using the FREQ procedure. Colostrum β-carotene was higher for BC cows. Colostrum from BC cows had increased a* [measures red (positive) to green (negative)] and b* [measures yellow (positive) to blue (negative)] colorimeter values, indicating that β-carotene altered colostrum color toward red and yellow. Supplementation did not affect colostral or calf IgG concentrations. Colostrum color indices were correlated with IgG concentrations as well as concentrations of β-carotene, retinol, and α-tocopherol. Before receiving colostrum, the concentration of β-carotene in calf serum was below the detectable threshold of 0.05 μg/mL. At 24 h of age, the number of calves with detectable β-carotene concentrations increased, with more calves from BC cows (52.1%) having detectable concentrations than calves from cows in the control group (6.1%). No differences in concentrations of retinol or α-tocopherol were observed in calf serum. Supplementation of β-carotene to cows decreased activities of gamma-glutamyl transpeptidase and glutamate dehydrogenase in calf serum. In pregnant cows already receiving adequate vitamin A, supplementation of β-carotene increased concentration of β-carotene in colostrum, altered colostrum color, and increased serum β-carotene in calves at birth.

The effect of retained placenta on the reproductive performance and its economic losses in a Holstein dairy herd

Retention of placenta (RP) is a failure of the fetal membrane to be expelled and remained from 8 to 48 hours, average 12 hours after parturition. There are a variety of risk factors for the occurrence of RP. So, the aim of this study was to quantify the relative risk of calving season, parity, and gestation length on the occurrence of RP, and assess the impact of RP on the subsequent reproductive parameters, and the economic losses. A data of 2940 purebred Holstein-Friesian cows were collected from reliable records of large commercial dairy farm, Sharkia governorate, Egypt. These cows calved during the period extended from January 2018 to December 2019. Cows that did not release the fetal membranes within the first 12 hours after calf expulsion were diagnosed with RP.Results of logistic regression analysis revealed that the important risk factors for the occurrence of RP were summer calving season and short gestation period. Odds ratio estimation for summer calving season compared to spring calving was 2.84. The probability of RP incidence in cows with shorter gestation period was 0.19 times more than cows with longer gestation length, and the total direct economic losses from RP was 47 $/cow.Finally, we can conclude that short gestation length and summer calving season are strongly correlated with the development of RP in dairy cows. Subsequently, the occurrence of RP significantly affects reproductive parameters resulting in economic losses in dairy herds.

Effects of prepartum supplementation of β-carotene in Holstein cows

Whether supplemental dietary β-carotene affects periparturient cows and vitamins A and E in cows when dietary vitamin A is adequate remains uncertain. Our objective was to assess the effect of β-carotene supplementation during the close-up dry period in a herd with adequate status of vitamins A and E but low in β-carotene. The study was conducted on a large commercial dairy farm in Indiana during early summer of 2015. Ninety-four multiparous Holstein cows were assigned to either control (CON; n = 47) or β-carotene (BC; n = 47) treatments. When locked in headgates each morning, each cow received a topdress of β-carotene (Rovimix, 8 g/d; provided 800 mg of β-carotene) or carrier from 21 d before expected calving until calving. Blood samples were collected at 21 ± 1 d (mean ± standard deviation) before expected calving (before treatments began), 7 ± 1 d before calving, immediately following parturition, and 7 ± 1 d postpartum. Blood serum was analyzed for vitamins A and E, β-carotene, cholesterol, and other metabolites and enzymes. Data were analyzed using the MIXED procedure in SAS (SAS Institute Inc.). Cows had low β-carotene concentrations (0.85 μg/mL) in blood serum before treatments began. Compared with CON cows, BC cows had higher overall mean concentrations of β-carotene (2.87 μg/mL vs. 0.73 μg/mL) and retinol (165 vs. 143 ng/mL). Cows fed BC had lower α-tocopherol in serum than cows fed CON (2.26 vs. 2.46 µg/mL). Cows fed BC had lower peak milk than cows fed CON (50.9 vs. 55.3), but total lactation milk yield did not differ significantly. No effects of BC were observed on days to conception (100 d) or times bred (2.4). Treatments did not affect incidences of ketosis, retained placenta, displaced abomasum, off feed, lameness, footrot, mastitis, or metritis. In conclusion, in pregnant cows already receiving adequate vitamin A but with low serum β-carotene concentration, supplementation of β-carotene increased concentrations of β-carotene and vitamin A in blood serum, but did not affect production, reproduction, or health.

Implementation of a pre-calving vaccination programme against rotavirus, coronavirus and enterotoxigenic Escherichia coli (F5) and association with dairy calf survival

BackgroundDiarrhea is one of the most common diseases and causes of death in calves during the first month of life. Pre-calving vaccination programme (PVP) against the most common diarrhea-causing pathogens could help to avoid this threat if hyperimmune transition milk (TM) is fed to calves throughout the whole susceptibility period. The aim of this retrospective cohort study was to reveal the implementation practices of PVPs in large commercial dairy farms and to compare calf-level mortality hazards during the first year of vaccination (V+ period) and a year before implementing the vaccination programme (V- period). A questionnaire was filled out in 15 large-scale dairy farms in Estonia that used PVP. The farms were assigned into three groups based on compliance with the vaccine directions for use and TM feeding practices. Calf-level time-to-event data was analyzed with an observation period of 21 days and on-farm mortality due to diarrhea being the event of interest.ResultsDuring the V+ period, a significant decline in diarrhea-induced calf mortality was identified in three out of six herds that followed vaccination instructions and fed TM for at least 14 days. On average, calf mortality hazard due to diarrhea decreased among these herds (hazard rate ratio (HR) = 0.72, 95% confidence interval (CI) 0.63; 0.81). In the group of correctly vaccinating herds where TM was fed for less than 14 days, diarrhea-induced calf mortality decreased in two herds and remained unchanged in two herds with average diarrhea-induced calf mortality hazard declining significantly during the vaccination period (HR = 0.24, 95% CI 0.14; 0.41). Among the three farms that deviated from the vaccination instructions, the average calf mortality hazard increased in the V+ period (HR = 1.61, 95% CI 1.21; 2.14).ConclusionsThis study revealed that implementing a PVP might aid to reduce diarrhea-induced calf mortality in large commercial dairy farms. There is a need to increase veterinarians´ and farmers´ awareness about the importance of including pregnant heifers into the vaccination programme and emphasize the importance of prolonged feeding of hyperimmune TM to calves.

Management-related factors in dry cows and their associations with colostrum quantity and quality on a large commercial dairy farm

The objective of this observational study was to evaluate the association of management-related factors in dry cows and colostrum quantity and quality in Holstein cows on a large commercial dairy farm. This study was conducted from January 2018 to December 2020 on a commercial dairy farm in Germany, milking approximately 2,500 Holstein cows. Dairy personnel recorded colostrum quantity (n = 7,567) and evaluated colostrum quality in a subsample of animals (n = 2,600) using a digital Brix refractometer. Generalized linear mixed models were constructed to evaluate the association of management-related factors and colostrum quantity and quality. Models were run separately for primiparous or multiparous cows. The outcome variable was either colostrum quantity (kg) or quality (%Brix). Average colostrum quantity was 4.0 ± 2.5 kg, 5.1 ± 3.4 kg, and 5.5 ± 3.5 kg for cows in lactation 1, 2, and ≥3, respectively. In primiparous cows (n = 2,351), colostrum quantity was affected by month of calving (greatest in April = 4.1 kg, and lowest in November = 3.2 kg), sex of the calf (female singleton = 3.50 ± 0.26 kg; male singleton = 3.76 ± 0.27 kg; twins = 2.97 ± 0.66 kg), stillbirth (stillbirth = 3.14 ± 0.39 kg; no stillbirth = 3.68 ± 0.31 kg). In multiparous cows (n = 5,216), colostrum quantity was affected by month of calving (greatest in May = 5.5 kg, and lowest in October = 3.8 kg), calving ease (calving ease 0 = 4.23 ± 0.26 kg; score 1 = 4.77 ± 0.21 kg; score 2 = 4.98 ± 0.22 kg; score 3 = 5.30 ± 0.22 kg), sex of the calf (female singleton = 4.42 ± 0.21 kg; male singleton = 5.00 ± 0.21 kg; twins = 5.03 ± 0.30 kg), stillbirth (stillbirth = 4.24 ± 0.38 kg; no stillbirth = 5.39 ± 0.11 kg), milk yield in previous lactation (+0.1 kg increase for 1,000 kg more milk yield in previous lactation), days spent in the far-off group (0.05 ± 0.003 kg for every day), and days in the close-up pen (0.06 ± 0.010 kg for every day). Average colostrum quality was 25.1 ± 3.4% Brix, 24.7 ± 3.3% Brix, and 27.6 ± 4.4% Brix for cows in lactation 1, 2, and ≥3, respectively. In primiparous cows (n = 817), colostrum quality was affected only by month of calving. Colostrum quality in primiparous cows was greatest in December (26.8%Brix) and lowest in August (23.9% Brix). In multiparous cows (n = 1,783), colostrum quality was affected by parity (lactation 2 = 25.2 ± 2.7% Brix; lactation 3+ = 27.9 ± 2.7%Brix), month of calving (greatest in February = 27.5% Brix, and lowest in August = 25.7% Brix), milk yield in previous lactation, and colostrum quantity. We observed a seasonal pattern for colostrum quantity and quality. Future intervention studies using multiple farms need to elucidate whether management of the photoperiod or length of exposure to close-up diets, or both, can help to optimize colostrum production.

Trends in antimicrobial use in livestock animals in Pakistan

Background: For decades, antimicrobials has been used in livestock for treatment and as growth promotor. It has been suggested that overall burden of antimicrobial resistance has increased due to contribution of antimicrobial use (AMU) from animals. Surveillance of AMU in animal production system is one of the key objectives of Pakistan National Action Plan on AMR. Therefore, aims of this study was to monitor AMU in commercial dairy and poultry farms in Pakistan. Methods and materials: Two large corporate commercial dairy farms and two commercial broilers farms in Pakistan were selected for monitoring AMU for a period of one year. For chicken, the amount of antimicrobial administered by the farmer to produce 1 kg of live chicken was estimated by dividing the total amount of antimicrobial used (milligrams) by the estimated body weight (kg) of the bird. In case of dairy, we used Antimicrobial Treatment Incidence (ATI) metrics, where, total amount of active-ingredient used in terms of the number of treatments as per the labelled daily dose animal (LDDA) over 1000 cows per day is evaluated as ATI. Results: In poultry, the most commonly used antimicrobials for therapeutic purposes were colistin (65 mg/kg), doxycycline (51.81 mg/kg) and tylosin (44.7 mg/kg). Colistin was used most frequently in all the 12 flocks on two poultry farms. In dairy cow, aminoglycosides (11.05 cow-days), penicillins (8.29 cow-days), and tetracyclines (8.1 cow-days) were the most frequently used antimicrobial-classes. A total of 6/11 (54.5%) antimicrobials belonged to WHO list of critically important for human use with highest priority. Conclusion: Intensive livestock farming in Pakistan is consuming alarmingly high amount of antimicrobials critical for human healthcare. These data provide a reference for further surveillance and research initiatives aiming to reduce AMU in food animals.

First Case Report on Quantification of Antimicrobial Use in Corporate Dairy Farms in Pakistan.

Intensive livestock farming has become indispensable to meet the rapidly increasing demand for animal-based nutrition in low- and middle-income countries (LMICs) where antimicrobials are frequently used for treatment and prophylactic or metaphylactic purposes. However, very little is known about the trends of antimicrobial use (AMU) in dairy animals in LMICs. The objective of this study was to quantify AMU in two large commercial dairy farms in Pakistan. A retrospective study was conducted at two large corporate commercial dairy farms located in Punjab province for the year 2018. AMU was calculated using three metrics: active ingredient (AI; kg) and milligrams per population unit (mg/PU; mg/kg), which quantifies the amount of AI used, and antimicrobial treatment incidence (ATI; DDDA/1,000 cow-days), which estimates the per-day number of treatments to 1,000 cows. Total on-farm AMU was found to be 138.34 kg, 65.88 mg/kg, and 47.71 DDDA/1,000 cow-days. Measured in ATI, aminoglycosides (11.05 DDDA/1,000 cow-days), penicillins (8.29 DDDA/1,000 cow-days), and tetracyclines (8.1 DDDA/1,000 cow-days) were the most frequently used antimicrobial classes. A total of 42.46% of all the antimicrobials used belonged to the critically important antimicrobials for human medicine as defined by the World Health Organization. Considerably high AMU was found compared to other farm-level studies across the world. This was the first study to quantify AMU in the dairy industry in Pakistan. Our results showed that corporate commercial dairy management practices are associated with increased antimicrobial consumption and highlight the need for antimicrobial stewardship programs to encourage prudent use of antimicrobials in commercial dairy.

A large-scale survey of Theileria orientalis infection in grazing dairy heifers in Kyushu, Japan.

The objective of the present study was to investigate the prevalence of Theileria orientalis infection and the influence of this disease on dairy grazing heifers in Kyushu by monitoring red blood cell (RBC) indexes, and to evaluate the efficacy of diminazene diaceturate treatment of T. orientalis-infected animals. A monthly epidemiological survey was conducted for Holstein heifers, which were reared from 10 to 16 months of age on a large commercial dairy farm and grazed on eight independent grasslands from April to November, 2009. During the survey, a total of 2,803 blood samples were collected from the 891 grazing heifers, in which the prevalence of T. orientalis infection was 52.4%. Compared with the heifers before infection, heifers with high parasitemia (more than 100 parasites per 104 RBC) had significantly decreased RBC indexes, such as RBC count, hemoglobin concentration, and hematocrit (P<0.05), whereas heifers with low parasitemia (less than 100 parasites per 104 RBC) had similar RBC indexes as those before infection. Treatment with diminazene diaceturate had lower efficacy in heifers with high parasitemia than those with low parasitemia (40.7% and 73.2% became negative, respectively, P<0.05). In summary, T. orientalis infection is a potentially serious problem in Kyushu, and it is important to routinely implement control programs for heifers that are grazed on grasslands in this region.

The effects of omega-3 α-linolenic acid from flaxseed oil supplemented to high-yielding dairy cows on production, health, and fertility

Among the long-chain fatty acids (FA), the omega-3 (n-3) FA have the most potent immunomodulatory activities. In the present large-scale study, we tested the effects of supplementation of α-linolenic acid (ALA) from flaxseed commenced at the dry period on milk yield, health and fertility of dairy cows. Cows in a large commercial dairy farm were randomly divided into two groups 21 days before expected calving. During the dry period, cows in the treatment group were fed a diet that contained, on a DM basis, 40 g/kg of an extruded flaxseed supplement (EFLX; n = 276); their postpartum diet contained 50 g/kg of the same supplement. The cows were group-fed, and based on average cow's intake, the EFLX cows consumed 80 and 220 g ALA/day per cow prepartum and postpartum, respectively. The control cows received a diet with a different composition but a similar content of nutrients (CTL; n = 240). A veterinarian routinely examined the cows 7 to 10 days after calving, treated them according to the farm's routine practice, and determined their body condition score at that visit and at peak lactation. Milk yield was 4.5% greater (1.8 kg/day; P < 0.0001), and fat (P < 0.0001) and protein (P = 0.002) contents were lower in the EFLX vs. CTL group. The proportion of n-3 FA in milk was 3.9 times higher in EFLX than in CTL cows (P < 0.0001), and the omega-6 (n-6):n-3 ratio in the milk fat decreased from 13.0 in the CTL cows to 4.1 in the EFLX cows (P < 0.0001). The unsaturated FA content in milk fat was 20.1% greater in EFLX than in CTL cows (P < 0.0001). Ketosis incidence was lower in the EFLX vs. CTL group, 23.5 and 31.2%, respectively (P = 0.05), and ketosis was less severe in the former (P = 0.03). The mortality rates in EFLX and CTL cows were 0.7 and 4.6%, respectively (P = 0.005). No differences were observed in conception rates at first or second insemination, but days from first service to conception and calving to conception were 17 (P = 0.07) and 18 days (P = 0.09) less in the EFLX cows, respectively. In conclusion, supplementation of EFLX to dairy cows from the dry period increased milk yield, decreased incidence of ketosis and severe metritis, reduced mortality, and tended to enhance fertility performance. Overall, ALA supplementation improved milk quality and was beneficial to the cow's health and fertility.

Epidemiological study to investigate the incidence and prevalence of clinical mastitis, peracute mastitis, metabolic disorders and peripartum disorders, on a dairy farm in a temperate zone in Japan

BackgroundOur aim was to investigate the incidence and prevalence of clinical mastitis, peracute mastitis, metabolic disorders, and peripartum disorders, and to examine factors affecting the prevalence of each disease in cows raised on a large dairy farm in a temperate climate in Japan. The present study was performed on a large commercial dairy farm with approximately 2500 Holstein cows. Data were collected from 2014 to 2018, and involved 9663 calving records for 4256 cows.ResultsThe incidence rate on the farm was 21.9% for clinical mastitis, 10.4% for peracute mastitis, 2.9% for metabolic disorders, and 3.2% for peripartum disorders. The prevalence rates for clinical mastitis, peracute mastitis, metabolic disorders, and peripartum disorders were 28.0, 13.3, 3.7, and 4.0%, respectively. In all four diseases, the probability of time to occurrence for each disease was associated with parity and calving season (P < 0.05). Regarding metabolic disorders and peripartum disorders, the probability of occurrence decreased during the first 10 days after calving.ConclusionsOur results showed that clinical mastitis occurred most often in this temperate zone, and that metabolic disorders and peripartum disorders occurred from calving to day 10 post-calving.

Machine learning algorithms, bull genetic information, and imbalanced datasets used in abortion incidence prediction models for Iranian Holstein dairy cattle

The ability to predict abortion incidence, especially in regions with high abortion rates (e.g., Iran), helps improve reproductive performance and, thereby, dairy farm profitability. The objective of this study was to predict pregnancy loss in Iranian dairy herds. For this purpose, the cow history records and bull genetic information available at 6 large commercial dairy farms with cows calved between 2005 and 2014 were extracted from an on-farm record-keeping software. Using WEKA, 12 commonly used machine learning (ML) algorithms were applied to the dataset. The algorithms belonged to 5 classifier groups which were Bayes, meta, functions, rules, and trees. The original dataset including herd-cow factors was randomly divided into 2 subsets: a training dataset and a test one (at a ratio of 60:40). The original dataset was combined with the bull genetic information to create a full dataset. The average abortion rate was 15.4 %, which represented an imbalanced dataset. Therefore, 2 down- and up-sampling techniques were additionally implemented on the original dataset (more specifically on the training one) to create 2 balanced datasets. This ultimately yielded 4 datasets; original, full, down-sampling, and up-sampling. Different algorithms and models were evaluated based on F-measure and area under the curve (AUC). Based on the results obtained, ML algorithms exhibited a high performance in predicting abortion when applied to the balanced dataset. However, their performance varied from 32.3 % (poor) to 69.2 % (medium upward) when applied to the imbalanced original dataset. In addition to the imbalance in the original dataset, the reason for these poor results were attributed to the high proportion of unknown risk factors underlying abortion incidence. Even when including the bull genetic information, it did not lead to any significant improvements in the prediction model. From among the datasets used, the Bayes algorithms outperformed the others in predicting pregnancy losses while rules had the worst performance. Furthermore, while the Bayes algorithms were not affected by the type of dataset (balanced or imbalanced), substantial increases in F-measure and AUC were observed for rules, trees, and functions with balanced datasets. Overall, the balanced models outperformed the others, with the down-sampling method exhibiting the highest performance. Despite the fact that the prediction models used in this study did not perform as expected, it was shown that they can be beneficially used to predict and reduce pregnancy losses, despite their moderate accuracy, especially when used for herds with high abortion rates and low reproductive performances.

Management practices associated with reproductive performance in Holstein cows on large commercial dairy farms

As a result of the increase in herd size and the intensification of production, the complexity of reproductive management has been growing in dairy herds. The aim of our study was to examine the associations of management practices and reproductive performance in Holstein cows on large commercial dairy farms. Management practices applied to cows were surveyed between 22 May and 6 November 2015 in 34 large Holstein-Friesian dairy herds in Hungary. Individual data of 23 784 cows that calved between 1 January 2014 and 31 December 2014 in the surveyed herds were gathered. Associations between the management practices and the reproductive parameters were analyzed by mixed effects models. Regarding heat abatement we found that ventilation with sprinklers was associated with the shortest breeding interval (P<0.01), the shortest calving to conception interval (P<0.01), and the highest odds of being pregnant by 200 days in milk (P<0.01). Solely ventilation showed similar (P>0.05) results to lack of heat stress protection. It was also revealed, that lack of a well-established voluntary waiting period (VWP) or a VWP shorter than 50 days was associated with less days to first service (P<0.01), shorter breeding interval (P<0.01) and calving to conception interval (P<0.05), as well as higher odds of carrying a calf by 200 days in milk (P<0.01) compared with those using a VWP of at least 50 days. Those farms that applied transrectal ultrasonography were more likely to use ventilation with sprinklers (P<0.05), hormonal synchronization (P<0.01) and to perform early pregnancy diagnosis followed by pregnancy recheck (P<0.05). The application of transrectal ultrasonography with one of the aforementioned practices was associated with reduced days to first service (P<0.05), shorter breeding interval (P<0.05) and higher odds of pregnancy at 200 days in milk (P<0.05). Our study highlights the management practices most closely related to improved reproductive performance, which are, therefore, suggested to be applied on dairy farms, considering the local circumstances of the individual farms.

Factors affecting the milk urea nitrogen concentration in Chinese Holstein cows

AbstractIn order to investigate the factors affecting milk urea nitrogen in Chinese Holstein cows, a large commercial dairy farm participated in a 30-month study. In this study, the mean milk urea nitrogen concentration was 11.75 mg/dl. The milk urea nitrogen reached its maximum value on day 90 of lactation for the first parity and the third or higher parities, but it peaked at the end of lactation for the second parity. The milk urea nitrogen of the first parity was lower than that of other parities. The milk urea nitrogen showed its minimum level in January, and reached its maximum in July. The milk urea nitrogen at the first month of lactation in cows calving in summer was higher than other seasons, while at the fourth month of lactation, the milk urea nitrogen of cows calving in autumn was significantly lower than in cows calving in other seasons. Positive correlations were observed between daily milk yield, net energy for lactation, crude protein and milk urea nitrogen for the first and third parities, but negative correlations were observed in the second parity. The milk urea nitrogen showed significantly positive correlations with fat content, total solid content and daily matter intake for all parities. A negative correlation was observed between milk urea nitrogen and protein content, with the exception of the second parity. For all data, as milk urea nitrogen concentration increased, milk protein content decreased. It has been recommended that milk urea nitrogen concentration should be evaluated in combination with parity, days in milk, season (or month), daily matter intake and dietary nutritional components, in order to improve the management and economic benefits of dairy farm.

Associations between management practices and major reproductive parameters of Holstein-Friesian replacement heifers

The aim of this study was to assess the relationship between the reproductive management practices and the performance of replacement heifers on large commercial dairy farms. The individual data of 14,763 heifers, first inseminated in 2014, were analysed from 33 Holstein-Friesian dairy herds in Hungary. The relationships between management practices and major reproductive parameters (age at first service, AFS; age at first calving, AFC; conception risk to first insemination, CR1; and pregnancy status at 20 months of age) were examined by mixed-effects models, with the herd as the random effect. The results showed that farms using oestrus detection aids experienced reduced AFS (p<0.001) and AFC (p=0.001). Observation of oestrus for shorter periods instead of continuously showed a tendency towards lower AFC (p=0.057) and was associated with higher odds of pregnancy at 20 months of age (p=0.020). Heifers on farms using sexed semen had younger AFS, but poorer CR1, compared to those using conventional semen exclusively (p<0.05). In addition, the odds of heifers being pregnant by 20 months of age was higher on farms with more experience using sexed semen (p=0.020). Frequent pregnancy diagnosis (i.e. more than once per week) was associated with younger AFC (p=0.023). Our results suggest the use of certain advanced reproductive management practices for heifer reproductive management in large dairy herds (e.g. oestrus detection aids), which can improve reproductive efficiency considerably, but are currently used only to a limited extent.

Detection of bacterial biofilm in uterine of repeat breeder dairy cows

Objective: To determine the possibility of presence of bacterial biofilm in the uterus of repeat breeder cows and to evaluate the effect of mucolytic agent in cleanup of uterus from biofilm. Methods: Twenty repeat breeder cows were selected from a large commercial dairy farm near Shiraz, Fars province, southern Iran. Uterine secretion samples were collected before and after uterine lavage with dimethyl sulfoxide (DMSO) 10% solution and periodic acid Schiff (PAS) staining was used to detect bacterial biofilm in uterine samples. After sampling, all cows were treated with two doses of PGF2α and intrauterine infusion of Cefquinome sulphate. Artificial insemination (AI) was performed after that. Results: Bacterial biofilms were found in 12 out of 20 animals (60%) in the first sampling with sterile saline lavage (before DMSO) and in 7 cows (35%) after DMSO lavage. Fourteen cows (70%) became pregnant after AI. This evidence showed the presence of bacterial biofilm in the uterus of dairy cows for the first time. Although non-significant, decrease in biofilm detection after DMSO lavage may suggest the potential ability of mucolytic agent for cleaning the uterus from bacterial biofilm. Also, high pregnancy rate after antibiotic treatment in the present study might be attributed to improved effect of antibiotic following lavage of uterine by DMSO. Conclusions: These findings should be investigated in future researches with more sample size.

A Metataxonomic Approach Could Be Considered for Cattle Clinical Mastitis Diagnostics.

Mastitis is one of the most costly diseases affecting the dairy industry, and identification of the causative microorganism(s) is essential. Here, we report the use of next-generation sequencing of bacterial 16S rRNA genes for clinical mastitis diagnosis. We used 65 paired milk samples, collected from the mastitic and a contralateral healthy quarter of mastitic dairy cattle to evaluate the technique as a potential alternative to bacterial culture or targeted PCR. One large commercial dairy farm was used, with one trained veterinarian collecting the milk samples. The 16S rRNA genes were individually amplified and sequenced using the MiSeq platform. The MiSeq Reporter was used in order to analyze the obtained sequences. Cattle were categorized according to whether or not 1 of the 10 most abundant bacterial genera in the mastitic quarter exhibited an increase in relative abundance between the healthy and mastitic quarters equal to, or exceeding, twofold. We suggest that this increase in relative abundance is indicative of the genus being a causative mastitis pathogen. Well-known mastitis-causing pathogens such as Streptococcus uberis and Staphylococcus spp. were identified in most cattle. We were able to diagnose 53 out of the 65 studied cases and identify potential new mastitis pathogens such as Sneathia sanguinegens and Listeria innocua, which are difficult to identify by bacterial culture because of their fastidious nature.

Lameness Prevalence and Risk Factors in Large Dairy Farms in Upstate New York. Model Development for the Prediction of Claw Horn Disruption Lesions.

The main objectives of this prospective cohort study were a) to describe lameness prevalence at drying off in large high producing New York State herds based on visual locomotion score (VLS) and identify potential cow and herd level risk factors, and b) to develop a model that will predict the probability of a cow developing claw horn disruption lesions (CHDL) in the subsequent lactation using cow level variables collected at drying off and/or available from farm management software. Data were collected from 23 large commercial dairy farms located in upstate New York. A total of 7,687 dry cows, that were less than 265 days in gestation, were enrolled in the study. Farms were visited between May 2012 and March 2013, and cows were assessed for body condition score (BCS) and VLS. Data on the CHDL events recorded by the farm employees were extracted from the Dairy-Comp 305 database, as well as information regarding the studied cows’ health events, milk production, and reproductive records throughout the previous and subsequent lactation period. Univariable analyses and mixed multivariable logistic regression models were used to analyse the data at the cow level. The overall average prevalence of lameness (VLS > 2) at drying off was 14%. Lactation group, previous CHDL, mature equivalent 305-d milk yield (ME305), season, BCS at drying off and sire PTA for strength were all significantly associated with lameness at the drying off (cow-level). Lameness at drying off was associated with CHDL incidence in the subsequent lactation, as well as lactation group, previous CHDL and ME305. These risk factors for CHDL in the subsequent lactation were included in our predictive model and adjusted predicted probabilities for CHDL were calculated for all studied cows. ROC analysis identified an optimum cut-off point for these probabilities and using this cut-off point we could predict CHDL incidence in the subsequent lactation with an overall specificity of 75% and sensitivity of 59%. Using this approach, we would have detected 33% of the studied population as being at risk, eventually identifying 59% of future CHDL cases. Our predictive model could help dairy producers focusing their efforts on CHDL reduction by implementing aggressive preventive measures for high risk cows.

The effect of sire predicted transmitting ability for production traits on fertility, survivability, and health of Holstein dairy cows

The major objective of this study was to evaluate, using survival analysis and multivariable regression models, the relationship of sire predicted transmitting ability (PTA) for production traits with their daughters' milk production, fat, and protein percentage (PROPCT), reproductive performance, postpartum disease incidence, and survivability. Data were collected from six large commercial dairy farms, and data analysis included 22,205 cows. Information regarding each sire's genetic evaluation included the following: PTA for fat yield (FAT), fat percentage (FATPCT), milk yield (MILK), protein yield, and PROPCT. Sire PTA was categorized into quartiles to facilitate data analysis and interpretation. Retained placenta, metritis, displaced abomasum, and clinical mastitis were diagnosed and treated by farm personnel. The overall average daily milk production, milk fat and PROPCT during the first 10 months of lactation was higher for the cows in the highest quartile of sire PTA, and cows in the lowest quartile had lower averages. There was no significant association between sire PTA for production traits and first test day fat to protein ratio or the incidence of postpartum disease. Sire PTA for MILK, FATPCT, and PROPCT were significantly associated with the hazard of pregnancy. The median days from calving to conception were 159, 155, 170, and 181 days for cows in the sire PTA for MILK quartiles 1, 2, 3, and 4, respectively. Sire PTA for PROPCT and FATPCT were also significantly associated with the hazard of pregnancy. The median days from calving to conception were 175, 189, 152, and 145 for cows in the sire PTA for PROPCT groups 1, 2, 3, and 4, respectively. Additionally, cows in the highest quartile for sire PTA for FATPCT had the lowest median days from calving to conception (144 days) and cows in lowest quartile had the highest median interval (177 days). Sire PTA for FAT was the only sire PTA significantly associated with the hazard of death/culling. When compared with the cows in the highest sire PTA for FAT quartile cows in the first, second, and third quartiles were at 1.51, 1.30, and 1.13 times higher hazard of death/culling, respectively. In conclusion, this study shows that high sire PTA for MILK and low sire PTA for milk fat and PROPCT are associated with decreased daughters' reproductive performance. Sire PTA for production traits were not found to be associated with postpartum disease incidence.