@conference {41681,
	title = {Effect of dairy cow breed on the metabolic adaptation to lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {66},
	year = {2006},
	month = {Jan},
	pages = {390-396},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Napier},
	abstract = {Three breeds (20 Friesian, 20 Jersey and 20 Jersey/Friesian crossbred multiparous cows) were used to determine the effect of breed on indicators of metabolic status and the post partum anovulatory interval (PPAI). Effect of breed on circulating concentrations of metabolites and hormones, liver mRNA levels and PPAI was established. Weekly blood samples were taken for the first 6 weeks of lactation. Liver biopsy samples were taken from a sub-sample of cows of each breed between 23-33 days post partum, to determine levels of expression of T-GHR, GHR-1A and IGF-1 receptors using RT-PCR. Milk progesterone analysis was used to determine PPAI. There was a significant breed effect on circulating concentrations of {\^a}-hydroxy butyrate (P<0.01), non-esterfied fatty acids (P<0.001), triacylglycerols (P<0.001) and leptin (P<0.01), with Jersey cows having higher concentrations of these hormones and metabolites than Friesian or crossbred cows. Despite the concentration differences between breeds, only leptin showed a significant difference (P<0.01) in the rate of change in concentration across time between the breeds. Jersey cows were observed to have shorter PPAI (34 vs 42 and 44 days for Friesian and crossbred cows respectively: SED 6 days) but this was not statistically significant (P=0.18). There was no difference in the expression of mRNA levels of TGHR, GHR-1A and IGF-1 receptors in the liver. It appears that grazing Jersey cows have a different fat metabolism, which affects the regulation of circulating leptin concentrations and this may have contributed to their apparent ability to return to cyclicity earlier. },
	issn = {1176-5283},
	author = {Back PJ and Meier S and Barnett CME and Cursons RT and Thomson NA}
}
@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}
}
