Vacuum levels and milk-flow-dependent vacuum drops affect machine milking performance and teat condition in dairy cows

Abstract

Different levels of claw vacuum during machine milking may influence milking performance and teat condition. The claw vacuum acts on the teat and is responsible for removal and transport of milk but is also causing potential effects on the teat tissue. In the absence of milk flow, the claw vacuum is similar as the system vacuum. During milk flow, the claw vacuum drops to lower levels depending on lifting height and tube length and diameter, which may influence milking performance and the mechanical load on the teat tissue. The goal of the present study was to investigate the effects of high system vacuum and extremely low claw vacuum during milk flow on milking performance and teat condition after milking recorded by ultrasound. Treatments were control (treatment 1) with a system vacuum of 42 and a minimum claw vacuum during milk flow of 33 kPa; treatment 2 representing a system vacuum of 50 kPa, with a minimum claw vacuum almost similar as treatment 1 (34 kPa); and treatment 3 with the same system vacuum as treatment 1 but a claw vacuum drop during milk flow down to 24 kPa. Total milk yield was similar in all treatments, but strip yield was lower in treatment 3 than in the other treatments. Milk flow was similar in treatment 1 and treatment 2, but was reduced in treatment 3, thus causing a prolonged milking time in treatment 3. Teat wall thickness was increased and teat cistern diameter was decreased in treatment 2 as compared with the other treatments. The results demonstrate that the minimum claw vacuum had the main influence on milking performance independent of the level of the system vacuum and related vacuum drops and a low minimum claw vacuum caused low milk flow and long milking times. Teat condition at the end of milking, however, was mainly dependent on the system vacuum, and the load on the teat tissue was obviously increased at a system vacuum of 50 kPa. This effect was obviously occurring toward the end of milking when milk flow decreased and hence the milk flow dependent vacuum drop disappeared. Therefore, an early cluster detachment should be considered to avoid an increased effect on the teat tissue. Estimates of simulated early detachment levels in the present study of up to 1,000g/min lead to the assumption of minimal milk loss at simultaneously shorter machine-on time through the avoidance of lowest milk flow at the end of milking.

Milking performance evaluation and factors affecting milking claw vacuum levels with flow simulator

“…The claw vacuum range was considered to be large if it exceeded 7 kPa (Reinemann et al . ; Mein & Reinemann ; Besier & Bruckmaier ; Besier et al . ).…”

“…; Rasmussen & Madsen ; Ambord & Bruckmaier ; Enokidani et al . ; Mein & Reinemann ; Besier & Bruckmaier ; Besier et al . ).…”

“…Inspections of milking machines (Reinemann et al . ; Mein & Reinemann ; Besier & Bruckmaier ; Besier et al . ) may be carried out through observations; through dry testing, in which the milking machine is activated and the machine is checked without actually performing milking; and through dynamic testing carried out during milking.…”

“…High claw vacuum during milking time directly damages the teat end. On the other hand, low claw vacuum reduces the milk flow rate, thereby extending the milking time, again damaging the teat end (Besier & Bruckmaier ). Inappropriate claw vacuum and claw vacuum range can therefore damage the teat end, and facilitate the occurrence of mastitis (Baxter et al .…”

“…In other words, if the performance of the milking machine is less than the cow's actual production capability, the milk yield may be limited by the performance of the milking machine, making milking performance a factor that inhibits milking appropriate to lactation physiology. This is a particular problem with high‐producing cows, and as it prolongs milking time and affects the health of the teat end (Besier & Bruckmaier ), it is a possible risk factor for mastitis. From the foregoing, maintaining the appropriate claw vacuum and claw vacuum range from low load to high load is important for ensuring milking that corresponds to the lactation physiology of the cow and for ensuring the health of the teat, and is essential for mastitis prevention, particularly in high‐producing cows.…”