@conference {89250,
	title = {Mastitis pathogens isolated from dairy cattle that were managed on conventionally or organically maintained matched farmlets},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {73},
	year = {2013},
	month = {Jan},
	pages = {183-185},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {<p>Mastitis is a common disease of dairy cattle causing significant economic loss (Seegers et al. 2003), which has been estimated to cost the New Zealand dairy industry $180 million annually (Malcolm 2006). It has been shown that dairy cattle in the first lactation are particularly susceptible to infections from environmental pathogens, including Streptococcus uberis(Woolford \&amp; Lacy-Hulbert 1996) and that this was the most common environmental pathogen, involved in the development of clinical mastitis of dairy cattle in New Zealand (Pankey et al. 1982, 1996; McDougall,1999). Studies completed in the Waikato region of New Zealand described the pathogens isolated from dairy cattle with clinical mastitis and reported that 27 to 75\% of cases were infected with Streptococcus uberis, whereas 9 to 10\% were Coagulase-negative-staphylococci(CNS), 3 to 5\% were Staphylococcus aureus, 2 to 5\% were coliforms and finally 1.5 to 4 \% were\&nbsp; Strep.</p>
},
	issn = {1176-5283},
	author = {Ullah Z and Margerison JK and Simcock DC and Thatcher A and Lopez-Villalobos N}
}
@conference {69533,
	title = {Influence of management techniques on the levels of mastitis in an organic dairy herd},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {70},
	year = {2010},
	month = {Jun},
	pages = {316-318},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Palmerston North},
	abstract = {n 2001, Massey University set up its Dairy Cattle Research Unit (DCRU) as a system comparison between organic and conventional farming. It is the only comparative grassland-based open grazing dairy study in the world. The DCRU was split into two similar farmlets; an organic unit of 20.4 ha carrying about 46 cows (2.27 cows/ha) and a conventionally farmed unit of 21.3 ha carrying about 51 cows (2.39 cows/ha). Each of the two units is managed individually according to {\textquotedblleft}best practice{\textquotedblright} for its particular type of management system. No attempt is made to replicate on one farm what is done on the other. The project has been described in detail by Kelly et al. (2006).},
	issn = {1176-5283},
	author = {Thatcher A and Petrovski KR and Fraser K}
}
@conference {41774,
	title = {Comparison of mastitis prevalence between an organic and conventional dairy herd from 2004 to 2006},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {68},
	year = {2008},
	month = {Jan},
	pages = {8-11},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Brisbane, Australia},
	abstract = {This study compared mastitis bacteriology and somatic cell counts (SCC) between an organic and a conventional dairy herd, each managed as a pastoral-based system, in the 2004/05 and 2005/06 seasons. Single quarter foremilk samples taken from both herds at calving, 14 days post-calving, mid-lactation and dry-off were cultured for bacteriological analysis. Individualcow SCC were obtained from monthly herd tests. The percentage of cows infected with Staphylococcus aureusand Streptococcus uberiswas generally higher in the organic herd than the conventional herd. However, these differences were only significant for S. aureusat midlactation 2005/06, when 56\% of the organic herd was infected compared to 23\% of the conventional herd (P <0.05), and for Str. uberisat dry-off 2005/06, when 7\% of the organic herd was infected but none of the conventional herd (P <0.001). The organic herd had a significantly higher mean lactation back transformed SCC than the conventional herd, in 2004/05 (96,921 vs. 75,608 cells/mL, P <0.05) and 2005/06 (103,968 vs. 63,096 cells/mL, P <0.0001). The 2004/05 season was the first time that a significant difference in mean SCC between the organic and conventional herds had been measured, since the organic and conventional dairy systems comparison trial was established in 2001.},
	issn = {1176-5283},
	author = {McLeod KLM and Holmes CW and Morel PCH and Dowson KR and Thatcher A and Shadbolt NM and Kelly TC}
}
@conference {41557,
	title = {A study of mastitis in two small experimental dairy herds managed either organically or conventionally during one year},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {148-152},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Mastitis infection status of two small herds located at the Dairy Cattle Research Unit of Massey University was assessed. Single quarter milk samples from 45 cows under organic production (first and second year of organic certification) and 50 cows under a conventional system were taken on four occasions: mid lactation (these samples were frozen); prior to the last milking before dry-off (season 2003/2004); before the first milking after calving and 14 days post calving (season 2004/2005). Milk samples were cultured for bacterial analysis. Somatic cell counts (SCC) from monthly herd tests, and clinical mastitis cases were recorded and analyzed.
The percentages of quarters with positive bacterial growth, and SCC, were generally higher in the organic herd, but differences were only significant for Staphylococcus aureus in all four sample periods, and for Streptococcus spp. 14 days post calving. The results suggest that in organic herds Staphylococcus aureus infections could become an important concern, because of constraints on the use of antibiotic treatments. Effective prevention of infections by this organism will be essential, in order to prevent high culling rates.
KEYWORDS: mastitis; organic dairy; New Zealand. },
	issn = {1176-5283},
	author = {Silva KE and Quinn AK and Morel PCH and Holmes CW and Thatcher A and Shadbolt NM and Kelly T}
}
