Impact of Machine Milking on Teat Dimensions

Abstract Text:

The objective of this study was to determine associations between machine milking and changes in teat dimensions. A total of 1,751 teats from 445 cows from the University of Wisconsin dairy herd were measured pre and immediately post-milking. The difference in teat length (Length), barrel width (Barrel) and teat tip diameter (Tip) before (PRE) and after (POST) machine milking was determined. Absolute change (Delta) on teat dimensions was calculated as POST-PRE measurements. Relative change (DeltaMeasureREL) was calculated as POST-PRE/PRE and expressed as percentage. Additional covariates included: Milk flow peak (PeakFlow), and parity (1, 2 or ≥3). Descriptive statistics were determined using PROC UNIVARIATE, FREC, GLM, and LOGISTIC of SAS version 9.3.

Means and SD for Pre-milking Length, Barrel, and Tip were 44.3±8.3, 23.9±3.7, and 19.6±2.3 mm, respectively. Means for PRELength were different for parity ≥3 (46.6 mm) when compared with 1 (42.8 mm) and 2 (43.6 mm) (P < .0001). Means for PREBarrel were significantly different among parities (P < .0001). Means for PRETip increased significantly with parity and were 19.3, 19.6, and 20.0 mm for parities 1, 2, and ≥3, respectively (P < 0.001). A positive association was found between PREBarrel and PeakFlow (P < .0001) for primiparous cows only.

Teat dimensions were affected by milking. During milking, teat length increased by 1.3 mm, teat barrel decreased by 2.2 mm and teat tip decreased by 0.7 mm. Changes in teat dimensions on length, barrel, and tip were not influenced by parity. Out of the 1,751 teats, 163 (9.3%) became congested at the barrel. Out of the 1,751 teats, 163 (9.3%) teat barrels became congested. Congestion was defined as PREBarrel measurements that were smaller than PostTeatBarrel measurements, implying congestion of the tissue during milking.  

Table 1:  Descriptive statistics for the impact of machine milking on teat dimensions

Teat dimension (n=1,751 quarters from 445 cows)	Mean±SD	Range
Pre-milking (mm)
PRELength	44.3±8.3	26.0-80.0
PREBarrel	23.9±3.7	14.0-50.0
PRETip	19.6±2.3	10.0-30.0
Post-milking (mm)
PostLength	45.6±8.5	24.0-100.0
PostTeatBarrel	21.7±2.8	12.0-40.0
PostTeatTip	19.0±2.2	10.0-30.0
Absolute change1 (mm)
DeltaLength	1.3±5.5	-20.0-26.0
DeltaBarrel	-2.2±3.0	-20.0-10.0
DeltaTip	-0.7±2.3	-10.0-8.0
Relative change2 (%)
DeltaLengthREL	5.5±23.4	-83.3-118.2
DeltaBarrelREL	-8.3±11.2	-50.0-50.0
DeltaTipREL	-2.5±12.4	-50.0-66.7

¹Postmilking value – premilking value.

²(Postmilking value – premilking value)/ premilking value x 100.

There was a strong association between pre-milking teat barrel dimension and peak milk flow for primiparous cows. Further research on teat dimensions changes and its influence on mastitis is required. 

Keywords: Dairy Cow, Induced Changes, Teat Dimension