Comparison of Methods of Evaluating Udder Health in Lactating Alpine Does

Udder infection in dairy goats can affect milk yield, composition, and result in economic losses. Early detection of mastitis while still in the subclinical stage assists in designing appropriate treatment. Milk from Alpine does was screened approximately 1 wk prior to the trial to identify animals having high (> 1.5 million cells/mL) and low somatic cell counts (SCC). Twelve Alpine does in their third parity (4 yr of age) were selected. Milk from each udder half of each doe was sampled for 4 consecutive mornings for the following determinations of normal vs. abnormal milk. Test methods included SCC using a Bentley Instruments SomaCount DairySpec Milk Component and Somatic Cell Detection machine (BSC) with SCC ≤ 1.5 million determined as normal; California Mastitis Test (CMT) score with score below 2 as normal; SCC using DeLaval cell counter (DCC) with a score ≤ 1.5 million determined as normal; electrical conductivity using the Mas-D-Tec^® (MDT) with a conductivity score < 5 determined as normal; estimation of SCC using PortaSCC^® (PSC) for Goats with score < 2 determined as normal; and lactate dehydrogenase levels using UdderCheck™ (LUC) that estimates level of lactate dehydrogenase using color strips (developed for dairy cattle) with a score < 3 determined as normal. Doe temperature was taken rectally and at 2 to 3 different places on the udder using an infrared thermometer. Because normal/abnormal milk is a binary response variable, a categorical analysis was conducted using a mixed model with fixed effects of method (BSC, CMT, DCC, MDT, PSC, or LUC), day (1, 2, 3, or 4), and side (left or right). Animal was the random effect and temperatures (rectal and average of udder) and days in milk (DIM) were used as covariates. Rectal temperature (P=0.28), average udder temperature (P=0.98), and side of udder (P=0.30) did not affect the determination of normal/abnormal milk; however, as DIM increased (P<0.01) so did the incidence of abnormal milk. If BSC is considered to be the benchmark for test method comparison, then only the PSC (P=0.35) gave comparable results; however, PSC tended to overestimate the frequency of abnormal milk samples. When analyzed within method, day of sampling did not affect determination for BSC (P=0.25), CMT (P=0.17), LUC (P=0.36), or PSC (P=0.13); however, the determination of normal/abnormal milk was affected by day for DCC (P<0.02) and MDT (P<0.01). In conclusion, PSC appears to be a reliable substitute for the expensive BSC system.