@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 {41730,
	title = {The use of neural networks to detect minor and major pathogens that cause bovine mastitis},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {67},
	year = {2007},
	month = {Jan},
	pages = {215-219},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Wanaka},
	abstract = {Bovine mastitis is caused by a diverse range of bacteria, broadly categorised as major or minor pathogens. The objective of this research was to develop an unsupervised neural network (USNN) model for detecting major and minor bacterial pathogens present in milk, based on changes in milk parameters associated with mastitis. A database of 4852 quarter milk samples with records for milk parameters and bacteriological status was used to train and validate the USNN model. Correlations (P<0.05) were found between the infection status of a quarter and its somatic cell score (SCS, 0.86), electrical resistance index (ERI, -0.59) and protein percentage (PP, 0.33). Due to significant multicolinearity, the original variables were decorrelated using principle component analysis. Sensitivity of the model for correctly detecting major and minor infections was 80\% and 89\%, respectively. Specificity of the model for correctly detecting non-infected cases was 97\%. The model is able to differentiate infected milk from non-infected based on milk parameters associated with mastitis. It is concluded that the USNN model can be developed and incorporated into milking machines to provide a reliable basis for mastitis control.},
	issn = {1176-5283},
	author = {Hassan KJ and Samarasinghe S and Lopez-Benavides MG}
}
@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 {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 {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}
}
