@conference {3672,
	title = {Using polymerase chain reaction to identify Streptococcus uberis in bovine milk: how does it compare with bacterial culture?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {75},
	year = {2015},
	month = {07/2015},
	pages = {20-23},
	address = {Dunedin},
	abstract = { Rapid identification of the pathogen responsible for an intramammary infection in a dairy cow can support herd management
decisions. Polymerase chain reaction (PCR) has become available to identify mastitis pathogens in milk, offering a rapid and
sensitive test. The performance of a commercial, real-time PCR assay was compared with traditional bacterial culture for the
identification of the most-frequent pathogen in New Zealand, Streptococcus uberis, during three stages of lactation. Aseptically
collected quarter-milk samples (n=6,848) were analysed by culture, and a subset (n=315) selected for PCR analysis based on S.
uberis infection status. Using culture as the reference test, PCR had a relative sensitivity of 89.0\%, and a specificity of 64.3\%
(kappa=0.49) for detecting S. uberis in milk collected at the first milking post-calving. The relative sensitivity and specificity
for samples collected in mid-late lactation were 89.3\% and 97.7\%, respectively, indicating a greater agreement between the two
tests later in lactation (kappa=0.88). Accurate diagnostic tests are necessary for mastitis management. In early lactation, when S.
uberis prevalence is high, bacterial culture should be used. The PCR assay tested in this study is most useful after the first month
of lactation.},
	issn = {1176-5283},
	author = {Steele NM and Williamson JH and Laven RA and Hillerton JE}
}
@conference {41800,
	title = {Effect of dry cow management on teat end bacterial contamination},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {68},
	year = {2008},
	month = {Jan},
	pages = {92-95},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Brisbane, Australia},
	abstract = {Two stock management practices were investigated for their effect on transfer of bacteria from the environment onto teat ends of dry dairy cows. Cows (n = 20) were required to walk or trot along races (1.2 km) deemed to be "clean" or "dirty". Cows walked along "clean" or "dirty" races were similar in dirtiness of the udder, and bacterial loading of the teats. Cows that trotted along {\textquoteleft}dirty{\textquoteleft} races showed a significant increase in degree of dirtiness of the teats and legs, and increased contamination of teats with coliform bacteria. Cows grazed for 24 hour periods using standard break-fencing systems, with (n = 20) or without (n = 20) the addition of back-fencing were assessed for the number and type of bacteria present on teat-ends. Cows that grazed paddocks with back-fencing had visually dirtier udders, but there was no difference in bacterial contamination of teats compared to those cows grazed without back-fencing. These studies suggest that the risk of bacterial contamination, and by extrapolation, risk of intra-mammary infection, may be mitigated by the speed with which cows are moved along races. However, grazing on muddy, soiled paddocks should not be discounted as a significant risk factor for mastitis. },
	issn = {1176-5283},
	author = {Turner S-A and Williamson JH and Lacy-Hulbert SJ}
}
@conference {41748,
	title = {Teat spraying before calving and Streptococcus uberis clinical mastitis in heifers : Brief Communication},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {312-314},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {Mastitis caused by the environmental pathogen Streptococcus uberisis a significant problem for New Zealand dairy farmers. Previous work on teat-spraying heifers three times a week for three weeks prior to calving demonstrated that a decrease in S. uberisteat-end contamination reduced the proportion of quarters infected with S. uberisat calving. This study evaluated the effect of teat-spraying heifers in the dry period for its ability to reduce S. uberisclinical mastitis (CM) after calving. Heifers from five commercial dairy herds (n=343) and one research farm (n=54) were enrolled to the study. Half of the animals from each herd were assigned to a Sprayed and the other half to a Not Sprayed group. Both groups were brought to the dairy three times a week, beginning three weeks prior to predicted calving dates and heifers in the Sprayed group were teat-sprayed with a commercially available iodine-basedteat sanitizer. Cases of CM that occurred in the  week after calving were sampled and submitted for bacteriological analysis. Incidence of S. uberisCM was 50\% lower in the Sprayed, affecting 3.6\% heifers vs. 7.4\% heifers of the Not Sprayed group (P=0.085). There was an indication that teat-spraying heifers three weeks prior to calving may have positive benefits in the reduction of CM caused by S. uberisafter calving.},
	issn = {1176-5283},
	author = {Lopez-Benavides MG and Williamson JH and Lacy-Hulbert SJ}
}
@conference {41905,
	title = {Mastitis in cows milked in an automated or conventional milking system in New Zealand},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {252-257},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {The viability of automated milking systems (AMS) for pasture-based dairying has been studied in New Zealand in the past four years. Automatic milking differs from conventional milk harvesting systems (CMS) in a number of ways, which may impact on udder health. These include fewer machines/cow, distributed vs. batch milking, variable milking intervals, automatic udder health monitoring systems, and pre and post-milking teat sanitation procedures. Three seasons of data from two pasture-based research farms that milked cows with either a two unit AMS or a 30 bail rotary CMS were compared. Quarter milk samples were collected routinely from all cows for bacteriological analysis during the 2002-03, 2003-04 and 2004-05 seasons, with sampling occurring throughout lactation and at detection of clinical mastitis (CM) cases. The number of cows in the AMS herd ranged from 94 to 196 and in the CMS herd, from 289 to 324 across the seasons. Clinical mastitis affected 7, 11, and 15 cows/100 cows/season in the AMS herd and 24, 23 and 14 cows/100 cows/season in the CMS across the three seasons, with Streptococcus uberis isolated from approximately 50\% of CM cases from both herds. Prevalence of S. uberis post-calving averaged 8\% of cows for the AMS and 16\% for the CMS across the three seasons. We compared several indicators of udder health between an AMS and a CMS herd managed under pastoral conditions. },
	issn = {1176-5283},
	author = {Lopez-Benavides MG and Williamson JH and McGowan JE and Lacy-Hulbert SJ and Jago JG and Davis KL and Woolford MW}
}
@conference {41650,
	title = {Prevalence of mastitis for cows of different genotypes milked for two consecutive seasons},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {236-240},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {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 infection status between genotypes in the second season (20\% and 18\% respectively). Results showed that although cows experienced less mastitis during the second spring of the lactation, the average cow SCC was higher during the extended part of the lactation. },
	issn = {1176-5283},
	author = {Lacy-Hulbert SJ and Summers EL and Williamson JH and Aspin PW and Kolver ES}
}
@conference {41888,
	title = {Teat spraying prior to calving may reduce the risk of heifer mastitis caused by Streptococcus uberis},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {168-171},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Heifer mastitis caused by Streptococcus uberis is a significant problem for New Zealand dairy farmers. The mechanisms of infection in the pre-partum period have not been fully elucidated but prior research has established that the teats of dairy cows are contaminated with significantly higher numbers of S. uberis during the dry period as compared to during lactation. It is hypothesised that gross teat-end contamination by these bacteria before calving is a significant risk factor for the entry of bacteria through the teat canal and establishment of infection. Regular disinfection of the teats in the dry period was evaluated as a means to reduce teat-end contamination and consequently to decrease the likelihood of glands developing an infection. Two groups of 27 heifers were assigned to either a {\textquoteleft}sprayed{\textquoteright} or {\textquoteleft}not-sprayed{\textquoteright} treatment. The sprayed heifers were teat-sprayed with a commercial iodine-based post-milking teat sanitizer three times a week for the last three weeks before calving. Before commencement of the experiment, teat-ends were swabbed to determine pre-existing contamination with S. uberis, which averaged 610 colony-forming units (cfu). Prior to calving, S. uberis counts on teat-ends were 560 cfu for the sprayed group and 1775 cfu for the non-sprayed group (p = 0.06). Bacteriology of milk from each gland at the first milking showed that 4\% of glands of the sprayed heifers were infected with S. uberis compared with 11\% for the non-sprayed heifers (p < 0.05). At the first herd test, heifers in the sprayed group had a lower SCC (380,000 cells/ml) compared to the non-sprayed group (790,000 cells/ml), although due to the small size of the study, this difference was not significant. It was concluded that teat-spraying in the dry period could reduce teat-end contamination and consequently the proportion of glands infected by S. uberis at calving. },
	issn = {1176-5283},
	author = {Lopez-Benavides MG and Williamson JH and Lacy-Hulbert SJ and Cursons RT}
}
@conference {41558,
	title = {Associations between Streptococcus uberis populations on farm races and climatic changes during a twelve-month period},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {153-156},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Streptococcus uberis is an important mastitis-causing pathogen in cows managed under pastoral conditions. The  influence of environmental conditions on  S. uberis ecology in dairy farms is unknown.  To evaluate associations  between climatic parameters and population levels of the bacterium on the farm, farm races were monitored for  S. uberis levels on a fortnightly basis from November 2003 to November 2004 at the Dexcel Lye research farm.  Higher  S. uberis contamination was observed in races where cow traffic was frequent and lower in areas where usage was  minimal.  Highest S. uberis contamination occurred in the month of August (630 cfu/g) and lowest in January (2 cfu/g).   Significant associations were observed between  S. uberis levels and relative humidity (r = 0.6), soil temperature at a  depth of 10 cm (r = -0.8), solar radiation (r = -0.7) and maximum air temperature (r = -0.7).  Around 70\% of S. uberis  clinical mastitis cases occurred in the non-lactating and calving periods, when S. uberis levels in races were above 100  cfu/g and solar radiation levels were low.  It is suggested that weather conditions have a significant impact on the  survival of S. uberis in the dairy farm environment.   },
	issn = {1176-5283},
	author = {Lopez-Benavides MG and Williamson JH and Cursons RT}
}
@conference {41470,
	title = {Influence of feeding level after drying off on incidence of mastitis and keratin plug formation in dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {48-52},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Prolonged postpartum anoestrous intervals (PPAI) are the major source of infertility in New Zealand dairy cows.  Postpartum supplementation with mono propylene glycol (MPG) was previously shown to reduce PPAI in heifers. The  present experiment tested this treatment in four large commercial dairy herds. During the six-week period preceding the  planned start of mating (PSM; week 0), cows were drenched either once (1xMPG) or twice (2xMPG) daily with 200 ml  MPG, or served as untreated controls (CON). Analyses were confined to the group of cows that were anoestrus at Week  {\~n} 6 or calved between Week {\~n} 6 and Week -4 relative to PSM (n = 662 to 669 per treatment). Change in body condition  score between Week {\~n} 6 and Week - 1(∆BCS), and proportion of cows that were anoestrus at Week {\~n}1 were influenced  by herd, age and time of calving (P<0.05) but not by treatment (P>0.1). Treatment did not influence the proportion of  anoestrous-treated cows inseminated after oestrus detection (n =263), or the pregnancy rate among all cows. Pre-mating  supplementation with MPG did not influence ∆BCS, the percentage of cows that were anoestrus at Week {\~n}1, or rates of  submission and conception. Change in BCS affected both milk yield and pregnancy rates, where cows that gained BCS  produced less milk but showed higher 6-week pregnancy rates. This study highlighted that key factors influencing the  percentage of anoestrus at PSM are cow age, time of calving and management of the herd. 

},
	issn = {1176-5283},
	author = {Summers EL and Lacy-Hulbert SJ and Williamson JH and Sugar BP}
}
@conference {41493,
	title = {Relationship between intramammary infection and teat characteristics},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {64},
	year = {2004},
	month = {Jan},
	pages = {147-149},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {The relationship between teat characteristics and intramammary infection (IMI) was investigated in 111 cows. These cows were scored visually on teat shape, teat-end shape and teat pigmentation. Subsequently, foremilk quarter samples were collected weekly for 14 weeks from calving to assess bacterial presence and somatic cell count (SCC). Teat shape and teat-end shape were combined and termed teat type. The distribution of teat type was cylindrical- round (34\%), funnel-round (21\%), cylindrical-flat (16\%) and bottle-round (9\%). Approximately 44\% of teats were fully pigmented (black/brown) while 25\% of teats were pigmented over less than 20\% of the surface area. The frequency of quarters that never became infected during the trial period was 78.4\% and the mean SCC was 69,000 cells mL-1. Among the infected quarters, the most frequently isolated pathogens were Corynebacterium bovis (45\%), coagulase negative staphylococci (CNS) (43\%) and Streptococcus uberis (6\%). Analyses showed no associations between teat characteristics and quarters not becoming infected, or between teat characteristics and bacterial pathogens in infected quarters. },
	issn = {1176-5283},
	author = {Lopez-Benavides MG and Williamson JH and Walters JB and Hickford JGH}
}
@conference {41412,
	title = {Diet and genotype affect milk lactoferrin concentrations in late lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {63},
	year = {2003},
	month = {Jan},
	pages = {87-90},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Queenstown},
	abstract = {Although lactoferrin (Lf) is a valued milk protein, little information is available on factors that affect its concentration in milk. Milk samples were collected during late lactation to determine if diet or cow genotype affected the concentration and yield of Lf in bovine milk. Holstein-Friesian (HF) cows (n=52) of either overseas (OS) or New Zealand (NZ) ancestry were fed either an all-pasture diet or a total mixed ration (TMR). Milk samples were collected from each cow during an AM milking in early March and late April. NZHF had a higher (P<0.05) Lf concentration than OSHF even though they produced less (P<0.05) milk. Genotype did not affect Lf yield, somatic cell count or the proportion of bacteriologically negative quarters. The Lf concentration in the milk of cows fed TMR was higher (P<0.05) than cows grazing pasture in April but not in March. Cows fed TMR also produced more (P<0.05) milk and a greater (P<0.001) yield of Lf than cows grazing pasture. Diet did not affect SCC, however only cows fed TMR had any bacteriologically positive quarters. A positive within-cow correlation (P<0.001) was found between Lf and SCC. The effect of diet on the concentration of Lf in milk requires further investigation. The genotype results suggest that NZHF have higher concentrations of Lf in milk than OSHF. Naturally high concentrations allow improved extraction efficiencies of Lf during processing. },
	issn = {1176-5283},
	author = {Turner S-A and Williamson JH and Thomson NA and Roche JR and Kolver ES}
}
@conference {41306,
	title = {Incidence of mastitis among cows of different genogtypes in differing nutritional environments},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {62},
	year = {2002},
	month = {Jan},
	pages = {24-29},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {Over three seasons (1998, 1999 and 2000) groups of Holstein-Friesian cows of New Zealand (NZ) or overseas (OS) origin were monitored for mastitis when managed in two contrasting systems. Cows were fed either on pasture or total mixed ration (TMR) with cows on TMR confined to small loafing paddocks or a concrete feedpad. All quarters were sampled for bacteriology at calving, at dry off, in mid and late lactation and when clinical mastitis was detected. Individual cow somatic cell counts (SCC) were determined weekly throughout lactation. In 1998, there was no difference in incidence of clinical mastitis but in later seasons, cows on TMR experienced significantly more clinical, and sub-clinical mastitis, than cows on pasture, probably reflecting differences in bacterial challenge within the environment. Genotype differences were less evident compared to dietary effects. Compared to NZ cows, OS cows experienced more sub-clinical infections in 1998 and more clinical infections in 1999 whilst in 2000, genotype effects were confounded by diet. Seasonal SCC was higher for OS cows in 1999 and 2000, reflecting differences in incidence of sub-clinical mastitis among treatment groups. Despite the strong influence of environment on mastitis incidence, genotype differences were detectable between NZ and OS cows. },
	issn = {1176-5283},
	author = {Lacy-Hulbert SJ and Kolver ES and Williamson JH and Napper AR}
}
@conference {41119,
	title = {Sealing of the bovine teat canal after dry-off.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {198-200},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Closed teats have proven more resistant to dry period mastitis than open teats. Natural rate of keratin plug formation within closed and open teats, and consequences of bacterial colonisation of the teat canal, were examined using 67 low somatic cell count cows. Cows were dried off without antibiotic therapy and teats assessed for closure status at 5, 10, 15 and 20 d after drying off. Weight and bacteriological status of the keratin plug was determined by reaming teats with a sterile pre-weighed tapestry needle 7 d prior to drying off and on one occasion post drying off. Initially (d 5), keratin weight for all teats increased by 100\% compared to lactating teats (4.89 mg/qtr). Between d 10-20, keratin weight from open teats (29\% of teats) was 34-55\% less than for closed teats. Subclinical infections in the teat canal significantly reduced likelihood of teats closing after drying off. },
	issn = {1176-5283},
	author = {Lacy-Hulbert SJ and Williamson JH and Day AM and Woolford MW}
}
@conference {39714,
	title = {Physical effects within the teatcup related to intra-mammary infection},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {41},
	year = {1981},
	month = {Jan},
	pages = {76-81},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	issn = {1176-5283},
	author = {Woolford MW and Williamson JH and Phillips DSM}
}
@conference {39681,
	title = {Milk production losses associated with clinical mastitis within identical-twin sets},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {40},
	year = {1980},
	month = {Jan},
	pages = {175-179},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	issn = {1176-5283},
	author = {Woolford MW and Williamson JH}
}
