Only the milk stored in the cisternal part of the udder is available for machine milking before milk ejection. Due to a high portion of milk stored in the alveolar part (more than 80%) the occurrence of milk ejection induced by tactile stimulation of the udder before milking is required for complete and fast milk removal. The normal milking liner pulsation also induces the milk ejection reflex during milking. However, the full milking vacuum after the removal of cisternal milk and before milk ejection causes the occurrence of bimodal milk flow curves and often a prolongation of milking time at simultaneously reduced milk flow rates (Bruckmaier and Blum, 1998) resulting in a higher risk of mastitis incidences (Rittershaus et al., 2001).The effect of tactile stimulation on the milk flow profile is mainly studied at the whole udder level (Bruckmaier and Blum, 1996). However, the most effective study to see the effects of milk ejection reflex on milk flow should be done at a quarter level (Tančin et al., 2003(Tančin et al., , 2006. Recently we have found a positive relationship between the duration of the decline phase of milk flow and somatic cell counts (Tančin et al., 2002). In the case of bimodal quarter milk flow a longer duration of the decline phase occurred as compared with non-bimodal curves (Tančin et al., 2005). However, there is no detailed study on how premilking stimulation influences the duration of the decline phase. The composition of milk including SCC changes in the course of milking (Bruckmaier et al., 2004). The milk ejection reflex induced before milking by tactile pre-stimulation could also influence the composition of milk in the course of milking. We expect that the pre-stimulation of the udder will improve the distribution of milk constituents during milking, which could be exactly described at a quarter level.The aim of this study was to investigate the milk flow patterns and the composition of milk in the Effect of pre-stimulation on milk flow pattern and distribution of milk constituents at a quarter level ABSTRACT: The aim of this study was to investigate milk flow patterns and milk composition in relation to premilking udder stimulation. The milk of one quarter of each of the sixteen cows was removed separately and in the course of milking it was divided into six fractions (P -cisternal milk during milking without stimulation and the first 300 ml during milking with pre-stimulation, 0-25%, 25-50%, 50-75%, 75-100%, 75-100%, MS-machine stripping) and into five portions (25%, 50%, 75%, 100%, 100% + MS). Two milkings were performed during two consecutive evening milkings with or without manual stimulation. Pre-stimulation resulted in a reduction of milking time, duration of the increase and decline phase of milk flow, stripping yield, but it increased the peak flow rate as compared to milking without pre-stimulation (P < 0.05). In both fractions and portions the content of fat increased steadily during milking and reached a maximum at MS. Lactose increased from P to 50-75% and then it decr...

The goal of this study was to evaluate the dose dependent changes in common milk and blood parameters for udder health after an intramammary (IM) infusion of five different doses of lipopolysaccharide (LPS, 100, 50, 25, 12.5 and 6.25 &mu;g, respectively). Ten Holstein Friesian cows randomly divided into five groups of 2 cows each were IM infused into one quarter with one LPS dose dissolved in 10 ml of saline. The contralateral quarter was infused with 10 ml saline (9 g/l). Milk samples were taken immediately before and 12, 24, 36, 48 and 60 hours after the treatment. All milk samples were analysed for somatic cell counts (SCC), lactose, sodium (Na), chloride (Cl) and electrical conductivity (EC). Two blood samples were taken immediately after milking for analysing leukocytes (WBC), polymorphonuclear neutrophils (PMN), Na and Cl. The SCC increased maximal at 12 hours after the LPS challenge and differed among LPS doses, as well as the area under curve from 0 to 36 hours (AUC 0&minus;36 h). There were no significant differences among LPS doses in lactose levels for the regression at 12 hours and AUC 0&minus;36 h. Lactose levels in milk from quarters receiving the lowest dose of LPS were lowest after 24 hours, whereas in all other groups lactose levels decreased maximal within the first 12 hours. The regression at 12 hours as well as the AUC 0&minus;36 h showed significant changes for Cl levels but not for Na and EC, respectively. Amongst all groups EC increased maximal within 12 hours and peak EC showed dose dependent differences with highest values at the highest LPS dose. There were no dose differences in WBC. Blood electrolytes showed only tendentially dose dependent differences for blood Na in AUC 0&minus;36 h. The results were possibly due to a great individual variance amongst all cows. In conclusion there are dose dependent differences in the response to LPS especially in milk parameters, which are likely caused by a greater tight junction damage by higher LPS doses. 100 &mu;g LPS seems to be a threshold between low and high doses of LPS. All doses used in this study induced signs of mastitis but there might be a low dose of LPS with only an enhancing effect on mammary gland immune status without inducing mastitis symptoms. This needs to be investigated for developing new ways of mastitis prophylaxis.

The aim of this study was to test whether a more pronounced oxytocin release induced by naloxone during milking causes higher efficiency of milk removal. Eight pregnant multiparousHolsteincows from second to fifth lactation were used for this experiment. The experiment was carried out during three consecutive days, i.e. six milkings (three morning and three evening milkings). During first and third evening milking in cross over design (four and four animals) 250 mg of naloxone or 10 ml saline was injected 5 min before the start of udder preparation. During these milkings 2 IU of oxytocin was injected i.v. after stripping and the amount of milk obtained in response to oxytocin injection was measured. Pre-milking naloxone treatment increased the milking-related release of oxytocin, however, only in six of eight cows. The stimulatory effect of naloxone on oxytocin release in the mentioned six cows differed individually from 4 ng/l to 132 ng/l. Naloxone treatment did not influence milk yield before stripping and stripping milk yield. However, naloxone treatment significantly reduced the amount of milk obtained in response to oxytocin injection. Peak flow rate tended to be higher after naloxone treatment. In conclusion, oxytocin release seems to be very important for the evaluation of different milking routines and milk removal environment with respect to the welfare of dairy cows.