Effect of stimulation intensity on oxytocin release before, during and after machine milking

Abstract

Release of oxytocin (OT) is essential for milk ejection in dairy cows (Lefcourt & Akers, 1983; Bruckmaier & Blum, 1998). During milk ejection, alveolar milk is shifted into the cistern, which causes an increase of intracisternal pressure (Bruckmaier et al. 1994). To initiate maximum milk ejection at the start of milking, increasing OT concentration beyond a threshold level is sufficient (Schams et al. 1983). Increasing OT concentration beyond this threshold has no additional effect on intracisternal pressure, i.e., milk ejection (Bruckmaier et al. 1994). Stimulatory effects of milking by hand or by machine or by suckling are well documented (Gorewit et al. 1992; Bar-Peled et al. 1995; Tancin et al. 1995; Bruckmaier & Blum, 1996). At the start of milking, stimulatory effects of machine milking without pre-stimulation or with a manual pre-stimulation and subsequent machine milking cause the release of comparable amounts of OT (Gorewit & Gassman, 1985; Mayer et al. 1985; Bruckmaier & Blum, 1996), whereas the timing of the applied pre-stimulation is important for the shape of the milk flow curve. Should the pre-stimulation period be too short, or absent altogether, the start of the main milk flow is delayed resulting in a bimodal milk flow profile (Bruckmaier & Blum, 1996). Furthermore, the stimulation of only one teat causes an OT release similar to that caused by stimulation of all four teats (Bruckmaier et al. 2001). However, milk production is greater for hand milking or suckling than for machine milking, possibly owing to higher OT concentrations (Gorewit et al. 1992; Bar-Peled et al. 1995).

Hormone release and behavior during suckling and milking in Gir, Gir × Holstein, and Holstein cows1,2

“…in Gir cows, as previously described in Holstein (Gorewit et al, 1992;Bar-Peled et al, 1995), Brown Swiss (Tancin et al, 1995), and Brown Swiss × German Braunvieh cows (Weiss et al, 2003), all of which are considered to be well adapted to milking when compared with Gir cows. Other investigators have also demonstrated that udder stimulation induces oxytocin release in Shami cows (Kaskous et al, 2006) and Murrah buffaloes (Thomas et al, 2005).…”

In vitro efficacy of some cattle drugs on bovine serum paraoxonase 1 (PON1) activity

“…Because of this property, oxytocin is often injected into cattle that are under stress or unable to produce much milk to enhance milk production 31 . However, some research indicates that administering oxytocin to stimulate uterine contractions in pregnant cows can lead to increased early embryonic death 32 . The present results indicate that oxytocin does not affect the activity of serum PON1 as it showed a very high IC 50 of 507.72 mg/mL (Table 1 and Figure 1).…”

Central and peripheral oxytocin profiles during milking in ewes

“…Thus, oxytocin release may be influenced by the type of stimulus (e.g., the suction exerted by the calf or milking) (MARNET; NEGRÃO, 2000; . This stimulus interferes with the ejection of alveolar milk and milk production (MARNET; NEGRÃO, 2000;WEISS;DZIDIC;BRUCKMAIER, 2003).…”

“…In ewes, the mother takes exclusive care of her own lamb (LÉVY et al, 1995). The release of oxytocin can be influenced by the type of stimulus (i.e., the suction exerted by the calf or milking, which can interfere with the milk ejection fraction and its production) (MARNET; LABUSSIERE, 1998;WEISS;DZIDIC;BRUCKMAIER, 2003).…”