Jane Lacy-Hulbert - Academia.edu (original) (raw)

Papers by Jane Lacy-Hulbert

Summary data for 36 herds enrolled in a study assessing the association between SCC and risk of i... more Summary data for 36 herds enrolled in a study assessing the association between SCC and risk of intramammary infection<br>

Extending the calving interval from the traditional 12-month to a 24-month calving interval has b... more Extending the calving interval from the traditional 12-month to a 24-month calving interval has been suggested as a practical solution for maximizing lactation yield per calving. Somatic cell count (SCC) and the incidence of mastitis were examined in New Zealand (NZ) and overseas (OS) Holstein-Friesian cows fed on pasture alone or supplemented with 3 or 6 kg DM maize/barley concentrates/cow/day during an extended lactation of up to 21 months. Average cow SCC was three-fold higher (P<0.001) in the extended or second season of the lactation compared with the first season, with NZ cows having a slightly higher SCC (P<0.01) in the second season compared to OS cows (191,000 and 115,000 cells/ml respectively). The SCC elevations occurred regardless of infection status of the udder. Although OS cows tended to have twice as many cases of clinical mastitis (P=0.01) in the first season compared to the NZ cows, affecting 59% and 27% of cows respectively, there was no difference in infect...

Extension farming systems journal, 2013

SmartSAMM is the New Zealand dairy industry's mastitis extension program, building on the SAM... more SmartSAMM is the New Zealand dairy industry's mastitis extension program, building on the SAMM Plan and Dairy Australia's Countdown program. SmartSAMM aims to achieve, by 2016, a national average bulk milk somatic cell count of 150,000 cells/mL, meeting the original SAMM Plan target set two decades ago. In 2012, SmartSAMM refreshed its 2009 plan with more rigour towards the 2016 targets, including use of ADOPT software. It appeared change on farm would need to be transformational rather than incremental. Farmer case studies with advisor input report transformational changes occurring. The challenge is to combine Technology Transfer, Problem Solving and Facilitation of SmartSAMM principles and interventions, through four complementary channels: 1) Marketing and communications, 2) The veterinary channel, 3) Advisor networks, and 4) Milk processors. The plan incorporates in the design Key Result Areas, and Success Outcomes Markers, as a basis for evaluation against targets and ...

A four-year study examined the effect of once a day (OAD) milking for complete lactations on mast... more A four-year study examined the effect of once a day (OAD) milking for complete lactations on mastitis and milk quality. The study comprised two herds of Jersey cows and two of Friesian cows, milked either OAD or twice a day (TAD) for a total of 4 lactations. Prevalence of intramammary infection (IMI) was determined by isolation of mastitis pathogens from quarter foremilk samples, collected aseptically at calving, mid lactation and at drying off. In the second and third years of the study, at drying off, cows milked OAD had three times as many (P < 0.01) quarters with IMI by major mastitis pathogens compared with TAD cows. Across all pathogens and years however, prevalence of IMI was not significantly or consistently higher for cows milked OAD compared with TAD. The somatic cell count (SCC) for uninfected cows milked OAD was approximately double that for TAD milked cows although this difference was only significant (P < 0.05) after the first 1-2 months of lactation had elapsed....

Mastitis in dairy cows compromises animal welfare and leads to significant economic losses. Udder... more Mastitis in dairy cows compromises animal welfare and leads to significant economic losses. Udder conformation, teat canal length and teat pigmentation may be associated with resistance to mastitis, and may provide a means to identify resistant cows. Associations between teat traits and prevalence of intramammary infection (IMI), and incidence of clinical mastitis (CM) was investigated in 805 Friesian-Jersey crossbred heifers. Bacteriological analysis was conducted on aseptically collected milk samples from each quarter at the first milking after calving, peak-lactation, mid-late-lactation, and before dry-off, and from glands diagnosed with CM. Teat characteristics were determined at peak-lactation and included: teat shape, teat-end shape, teat pigmentation, teat length, height of teat end above ground and teat angle (deviation from vertical). Greater odds of infection were observed between specific teat traits and prevalence of IMI at calving, and occurrence of new IMI through lact...

Two groups of 70 cows, including 51 identical twin sets, were grazed at either an unrestricted (1... more Two groups of 70 cows, including 51 identical twin sets, were grazed at either an unrestricted (14 kg dry matter intake/day; DMI/d) or restricted (6 kg DMI/d) daily pasture allowance for two weeks after drying off (DO). Incidence of new intramammary infection (IMI) and teat open/closed status was assessed at 7, 14 and 21 days after DO. Keratin plug formation was determined on a subset of 40 cows at 7 and 14 days after DO. Number of clinical mastitis (CM) cases and total new IMI did not differ between cows maintained on unrestricted or restricted DMI. However Streptococcus uberis was isolated from more new IMI in unrestricted animals than restricted animals (11.7% vs. 4.6 % of quarters respectively; P <0.01). At 7 and 14 days after DO, more teats were classified as open in the unrestricted group compared to the restricted animals (57% vs. 43% of quarters respectively; P <0.01). However weight of keratin collected from teat canals did not differ between nutritional treatments. R...

The Journal of dairy research, 2018

Inflammation of the mammary gland following bacterial infection, commonly known as mastitis, affe... more Inflammation of the mammary gland following bacterial infection, commonly known as mastitis, affects all mammalian species. Although the aetiology and epidemiology of mastitis in the dairy cow are well described, the genetic factors mediating resistance to mammary gland infection are not well known, due in part to the difficulty in obtaining robust phenotypic information from sufficiently large numbers of individuals. To address this problem, an experimental mammary gland infection experiment was undertaken, using a Friesian-Jersey cross breed F2 herd. A total of 604 animals received an intramammary infusion of Streptococcus uberis in one gland, and the clinical response over 13 milkings was used for linkage mapping and genome-wide association analysis. A quantitative trait locus (QTL) was detected on bovine chromosome 11 for clinical mastitis status using micro-satellite and Affymetrix 10 K SNP markers, and then exome and genome sequence data used from the six F1 sires of the exper...

Journal of Dairy Science, 1999

Twenty-four monozygous twinsets in late lactation (>210 d in milk) were used to examine the effec... more Twenty-four monozygous twinsets in late lactation (>210 d in milk) were used to examine the effects of feed restriction and milking frequency prior to drying off on milk yield and composition in a pastoral dairying system. Cows were assigned to one of four treatment groups for 26 d and were milked either twice or once daily and given either unrestricted or restricted access to feed. Dry matter intakes averaged 16 or 8 kg per cow per day, and diets comprised ryegrass and white clover pasture supplemented with 15% pasture silage. Feed restriction and once daily milking reduced milk yield and increased concentrations of milk fat and protein. Somatic cell count was increased by feed restriction only. Production losses caused by feed restriction were nearly threefold higher than were those for once daily milking. Yields of components that were mammary synthesized and serum derived were reduced by feed restriction, in accordance with milk volume reduction. Plasma lactose concentration increased with once daily milking only and indicated enhanced permeability of mammary tight junctions. Both feed restriction and once daily milking compromised milk quality, but increased leakage of serum components into milk via mammary tight junctions was deemed to occur only for once daily milking.

Journal of Dairy Science, 2009

The effect of infusing a mixture of 5 Streptococcus uberis strains into mammary quarters of 10 la... more The effect of infusing a mixture of 5 Streptococcus uberis strains into mammary quarters of 10 lactating cows was investigated. All 5 strains, which included 2 originally isolated from the dairy environment and 3 from clinical cases of mastitis, were capable of establishing an intramammary infection when infused individually. However, when the 5 strains were infused together, a single strain predominated in 7 out of 10 quarters. One strain in particular prevailed in 4 mammary quarters and was also found to inhibit the growth of the other 4 strains with deferred antagonism on esculin blood agar. The genes required for the production of bacteriocins nisin U and uberolysin were identified in this strain, whereas the other 4 strains contained only uberolysin genes. Direct competition may have occurred between strains within the mammary gland but competition was not apparent when cultured together in UHT milk, where no strain predominated. Although the mechanism is unknown, these results imply that a selection process can occur within the mammary gland, leading to a single strain that is detected upon diagnosis of mastitis.

Composite 24 h milk samples were collected for detailed milk analysis from each quarter of ten co... more Composite 24 h milk samples were collected for detailed milk analysis from each quarter of ten cows known to be free of intrama mmary infection. Milk yield and concentration of lactose and serum albumin (BSA) were significantly higher (P<0.001), and chloride io ns significantly lower (P<0.001), in hind compared with fore quarters. Four cows developed clinical intramammary infection when su bsequently challenged in the left hind quarter with Streptococcus uberis. For all parameters measured, i.e. protein, lactose, somatic cell count (SCC), BSA and immunoglobulins (IgG), milk from the infected quarter differed significantly from the uninfected quarters. No effect of inf ection was observed in quarters adjacent to the infected quarter, except for SCC, which increased significantly (P<0.001) in the uninfecte d hind quarter. Milk proteolytic activity in the infected quarter increased significantly (P<0.001) due to increased conversion of plasmin to p lasminogen.

Journal of Dairy Science, 2007

Microbiological and molecular tools were used to monitor Streptococcus uberis populations on farm... more Microbiological and molecular tools were used to monitor Streptococcus uberis populations on farm tracks and paddocks on a dairy farm during different seasons of a year to identify and profile potential environmental niches of Strep. uberis in a pasture-based dairying system. Farm tracks of high or low cow traffic were sampled every 2 wk for an entire year and Strep. uberis numbers were enumerated from a selective medium. During each season of the year, paddocks were sampled for the presence of Strep. uberis before and after grazing by dairy cows. Farm tracks of high cow traffic generally had greater concentrations of Strep. uberis isolated compared with tracks with less cow traffic, but there was also significant variation in the concentrations of Strep. uberis contamination among seasons, being highest in winter and lowest in summer. The bacterium was detected in paddocks only after cow grazing had occurred, but the bacteria could still be detected in soil for up to 2 wk following grazing in winter. Multilocus sequence typing showed great heterogeneity, with some commonality between farm track and milk isolates, which may help explain cow-to-environment or environment-to-cow transmission of the bacterium in the dairy setting.

$Research paper thumbnail of Dairy cows produce cytokine and cytotoxic T cell responses following vaccination with an antigenic fraction from Streptococcus uberis$

Veterinary Immunology and Immunopathology, 2014

Streptococcus uberis is a major cause of mastitis in dairy cows worldwide and currently, there is... more Streptococcus uberis is a major cause of mastitis in dairy cows worldwide and currently, there is no vaccine commercially available against this form of mastitis. In the current study, cell-free extracts (CFE) were prepared from each of three different S. uberis strains, designated as #3, #24 and #363 representative of the three main sequence types of S. uberis that cause mastitis in New Zealand. These proteins were formulated into vaccines with Emulsigen-D and the immunogenicity of the vaccines was determined in both calves and dairy cows. Two groups of calves (n=5/group) were vaccinated subcutaneously with CFE from strain #24 or strains #3, #24 and #363 formulated with Emulsigen-D, respectively. A third group (n=5) was vaccinated with CFE from the three strains formulated with Emulsigen-D and also containing recombinant bovine granulocyte macrophage colony-stimulating factor while, a control group (n=5) was not vaccinated. Vaccinated animals produced strong antibody responses to the S. uberis antigens and an antigen-specific cytotoxic effect against blood monocytes/macrophages that had phagocytosed S. uberis, with no significant differences in responses observed between the three vaccinated groups. In a second trial, the safety and immunogenicity of the vaccine containing CFE from all three strains of S. uberis and Emulsigen-D was determined in dairy cows. A group of six cows were vaccinated subcutaneously at 3 and 1 week prior to dry off and revaccinated 2-3 weeks before calving. Immune responses in blood and mammary gland secretions (MGS) were monitored during the dry period and in the subsequent lactation. The vaccine was well tolerated with no adverse effect from vaccination observed in any of the cows. Vaccination induced an antigen-specific cytotoxic effect against blood monocytes/macrophages that had phagocytosed S. uberis, moderate antigen-specific IFN-γ responses in blood and strong antibody responses in both blood and MGS. In conclusion, the results suggest vaccination of cattle with S. uberis CFE by the subcutaneous route can induce both cellular and humoral responses.

Veterinary Research Communications, 2011

The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary glan... more The presence, phenotype and function of Streptococcus uberis-specific T cells in the mammary gland secretion (MGS) and blood of cows exposed to S. uberis were assessed. MGS T cells in the udder were purified and incubated with autologous blood monocytes as antigenpresenting cells (APC). Most cows, irrespective of prior S. uberis infection status and lactation status, were shown to have S. uberis-specific T cells both in MGS and in the blood. When cells from a subgroup of cows were studied, it was found that the S. uberis-specific T cells produced high levels of interferon-gamma (IFN-γ), but low levels of interleukin-10 (IL-10). A high percentage of responding T cells were of the CD8 + memory (CD45RO) subset. T cells from the MGS specific for S. uberis were propagated from animals during the drying off period and expanded in vitro using interleukin-2 (IL-2) and S. uberis antigens. This led to the accumulation of T cells of the CD8 + subset bearing memory cell markers (CD45A − , CD45RO +), which released high levels of IFN-γ. Four of the five T cell lines derived from the MGS of three animals had substantial direct killing activity towards S. uberis in vitro. It is concluded that there is an emergence of S. uberis-specific bactericidal T cells in the MGS of cows after infection or environmental exposure to S. uberis. Vaccines aimed at activating and expanding this T cell population in the mammary glands of cattle may offer an avenue for the prevention of mastitis caused by S. uberis.

Veterinary Microbiology, 2009

Heifers managed under pastoral conditions are at risk from Streptococcus uberis mastitis infectio... more Heifers managed under pastoral conditions are at risk from Streptococcus uberis mastitis infections at calving. A total of 397 heifers from six farms around New Zealand were enrolled in a study to identify and enumerate S. uberis on teat-ends of heifers in the peri-partum period, and to understand the effect of teat-spraying in the pre-calving period on the prevalence and incidence of S. uberis mastitis post-calving. Heifers were randomly assigned to Control or Sprayed groups. Sprayed heifers were teat-sprayed once, three times a week (Monday, Wednesday and Friday) with a commercial iodine-based teat sanitizer, starting at 3 weeks prior to calving and ending at day of calving. Across three farms, all glands of cows in both groups were sampled at calving to determine S. uberis intra-mammary infection (IMI) prevalence. For all farms, clinical mastitis (CM) cases detected during the week after calving were sampled and submitted for bacteriological analysis. Swabbing of teat-ends of 54 heifers from one farm showed that heifers had a pre-existing S. uberis contamination averaging 610 colony-forming units per swab (cfu/swab), at 3 weeks prior to calving. At calving, teat-end contamination was 560 cfu/swab for Sprayed heifers and 1775 cfu/swab for Control heifers. Two weeks after calving, teat-end contamination was similar between both groups, at 30 cfu/swab. The prevalence of S. uberis IMI was significantly lower in the Sprayed (3.5% glands) vs. the Control (7.4%) heifers in the first week after calving. There was a trend for Sprayed heifers (3.6% heifers) to have a lower incidence of S. uberis CM compared with Control heifers (7.4% heifers). It is concluded that teat-spraying in the dry period is a management option that could contribute to controlling heifer S. uberis mastitis in the transition period.

Veterinary Immunology and Immunopathology, 2006

The aim of this study was to compare the ability of milk macrophages and macrophages from the mam... more The aim of this study was to compare the ability of milk macrophages and macrophages from the mammary gland secretions during the mid-dry period for their interaction with the mastitis-causing Streptococcus uberis. We also aimed to determine if S. uberis induced the release of the cytokine tumour necrosis alpha (TNF-a) and the bactericidal moiety nitric oxide (NO) from milk macrophages of lactating cows and macrophages from the mammary gland secretions at the mid-dry period. Macrophages were isolated from the mammary gland secretions of cows during the mid-lactation or mid-dry period, and compared with blood monocytes for their interaction with the important mastitis-causing pathogen S. uberis. When infected in vitro with S. uberis, milk macrophages from lactating cows with S. uberis released modest amounts of the cytokine tumour necrosis factor alpha (TNF-a) (139 pg/ml) and the bactericidal moiety nitric oxide (NO) (3-4 mM of nitrite). Blood monocytes from lactating cows released significantly higher amounts of TNF-a (345 AE 143 pg/ml) and NO (7 AE 2 mM of nitrite) after interaction with S. uberis, compared to milk macrophages (P < 0.01 for both TNF-a and NO). Stimulation of blood monocytes with the cytokine interferon-gamma (IFN-g) enhanced significantly the release of NO and TNF-a, but IFN-g did not significantly enhance the production of NO and TNF-a by milk macrophages from lactating cows. Milk macrophages from all lactating cows failed to kill S. uberis efficiently, and this lack of killing was unaffected by prior treatment with gamma interferon (IFN-g) (P > 0.05). Rather, S. uberis multiplied significantly inside infected milk macrophages from lactating cows, with a twofold increase in bacterial numbers at 2 h post-infection. Milk macrophages from lactating cows were able however, to kill a significant proportion (50-60%, P < 0.01) of phagocytosed Staphylococcus aureus. Blood monocytes from all cows were found to exert significant bactericidal activity against S. uberis. There were no significant differences in the bactericidal activity of milk macrophages obtained from lactating cows with low somatic cell counts (SCC; <10 5 ml À1) compared with those with a mildly elevated SCC (>10 5 ml À1) (P > 0.05). In contrast, mammary gland secretion macrophages isolated from the same cows in the mid-dry period killed a significant proportion of phagocytosed S. uberis (50-65% of ingested S. uberis killed, P < 0.01) although cytokine production in response to in vitro bacterial infection was low. We conclude that the bactericidal activity of mammary gland secretion macrophages against a virulent strain of S. uberis is low during the lactation period. In addition, our data indicate that S. uberis is not a strong inducer of NO and TNF-a in macrophages from the milk or mammary gland secretions of cows during the drying off period. Finally, IFN-g does not activate milk macrophages or macrophages from cows during the lactating period or mammary gland secretions during the drying off period.