Effect of incomplete milking on milk production rate and composition with 2 daily milkings

Abstract

The primary aim of this study was to assess the effects of incomplete milking on milk secretion and milk composition at the quarter level. Twelve cows were enrolled beginning at 5 d in milk and remained on study through 47 d in milk. Half of each contralateral udder was incompletely milked (treatment), detaching the teat cup early to leave approximately 30% of the total milk yield behind. This target milk remaining in the gland was based on weekly calibration milking measurements of quarter total milk yield. Control quarters were milked completely until milk flow had decreased to 0 kg/min based on visual assessment. Harvested milk yield was measured twice daily at each milking, and milk components (fat, protein, lactose, solids nonfat, milk urea nitrogen) and somatic cell count, were measured twice weekly at the quarter level. The experimental unit in this design was the half-udder, and a mixed-model approach was used to assess the main and interactive effects of experiment week and treatment on milk production rate, milk remaining in the gland, and milk composition. The effect of treatment on milk production rate was significant, with the average control half-udder producing 0.97 kg/h and the treatment half-udder 0.73 kg/h. The effect of week on milk production rate and the interaction of week × treatment were also significant. The effect of treatment on milk remaining in the gland was significant, illustrating that an increase in milk remaining in the cisternal compartment had been achieved. We detected a significant decrease in milk lactose percentage in treatment half-udders, and a significant increase in somatic cell count (log). The increase was relatively small, from a geometric mean of 26,300 cells/mL in control quarters to 48,300 cells/mL in treatment quarters. The decrease in milk production rate in treatment half-udders supports current knowledge about how mammary epithelial cell secretion, proliferation, and apoptosis are modulated by autocrine-paracrine factors.

Effects of simulated quarter and udder teat cup removal settings on strip milk and milking duration in dairy cows

“…Our study suggests that the SM Q for these treatments would have been on the order of 0.1 kg, 0.3 kg, and 0.6 kg, respectively. Penry et al (2017) and Kuehnl et al (2019) reported significantly lower milk production rates when early-lactation cows were severely undermilked, leaving about 1.4 kg of SM in a quarter. Our study suggests that MFR1.0 Q would produce a similar SM Q .…”

“…In an AMS, Krawczel et al (2017) saw no effect on SCC or milk yield when teat cup milk flow rate switch-point was increased from 0.06 kg/min to 0.48 kg/min at the quarter level. The study by Penry et al (2017) measured the milk left in the quarter, and thus it is not comparable with a specific milk flow rate switch-point used in other studies. As a reference, the studies by Edwards et al (2013) and Clarke et al (2008) reported increases in strip milk of approximately 0.3 L at the udder level when increasing the milk flow rate switch-point up to 0.8 kg/min.…”

“…The influence and causal effect of milk remaining in the gland on SCC is less clear. A study by Penry et al (2017) found a slight increase in SCC from 26,300 to 48,300 cells/mL and a 25% reduction in milk production rate when approximately 30% of the milk was left in a half udder when cows were milked twice per day. A subsequent study by Kuehnl et al (2019) showed that regardless of whether half udders were milked 2 or 3 times per day, they had 27% lower milk production and SCC increased by 25,700 cells/mL compared with half udders milked completely.…”

A randomized controlled trial on the effect of incomplete milking during the first 5 days in milk on culling hazard and on milk production and composition of dairy cows

“…In that study, however, the treatment was applied for a longer period (from 5 to 47 DIM) compared with our study (1-5 DIM). Moreover, due to the half-udder design used by Penry et al (2017), we could hypothesize the levels of galactopoietic hormones to be the same for both treated and control quarters; thus, the response observed in treated quarters in their study was possibly solely due to local quarter-level response (rather than local and central changes). In our study, the treatment could have induced both local and central responses, but minimal differences in milk yield were observed between groups.…”

“…Although ran in a different species and with a different study design, the results observed by Wilde et al (1989) also support the findings of the current study, where a relatively short period of incomplete milking was used. A more recent study from Penry et al (2017), conducted in dairy cows, showed that an incompletely milked half-udder (defined as approximately 30% of total milk yield left behind at the end of milking) had lower milk production rate (0.73 kg/h) than a completely milked half-udder (0.97 kg/h), without an effect on milk composition. In that study, however, the treatment was applied for a longer period (from 5 to 47 DIM) compared with our study (1-5 DIM).…”