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Evaluation of breed and udder characteristics on somatic cell count and udder pathogens in lactating Holstein and Jersey cows.

M. W. Hollis

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06-22-2020

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Abstract:

M82
Evaluation of breed and udder characteristics on somatic cell count and udder pathogens in lactating Holstein and Jersey cows.
B. M. Brown, M. W. Hollis*, J. G. Carter. Middle Tennessee State University Murfreesboro, TN.

The objective of this study was to evaluate the impact of physical udder characteristics and breed on hygiene scores (HS), milk yield (MY), conductivity (COND), SCC, and bacterial cultures (BC) in lactating Holstein and Jersey dairy cows housed in a compost-bedded pack barn. Lactating Holstein and Jersey (n = 10 each) cows were evaluated during a 6-wk period. Milk samples were collected as a sterile composite from all 4 quarters during one milking/wk and SCC was determined using the DeLaval Cell Counter DCC. If SCC ≥350,000 cells/mL, the sample was cultured to determine bacterial species. Milk samples were cultured using a Tri-plate agar including Factor, MacConkey, and Focus media (University of Minnesota Easy Culture). Cows were evaluated once/wk using a multi-zone hygiene scoring system for udder cleanliness (1 = very clean to 4 = very dirty; Cook, 2002). Udder measurements were taken during wk 1 and included udder depth and circumference, and teat length. Milk yield and COND were measured daily and averaged by wk using the AfiMilk parlor system (Afimilk, Kibbutz Afikim, Israel). Statistical analysis of MY, COND, and udder measurements were conducted using the MIXED procedure in SAS (v9.4). Analysis of HS incidence and BC species counts were evaluated using the FREQ procedure in SAS (v9.4). No differences in BC, SCC, or physical udder characteristics were observed among breeds. Holstein cows produced more milk than Jerseys (37.6 and 26.5 � 3.01 kg/d, respectively; P = 0.0181) and had greater COND (9.70 and 8.81 � 0.15 mS/cm, respectively; P = 0.0005). Jerseys exhibited improved udder (64.4 vs. 25.4% score 1 and 28.8 vs. 64.4% score 2, respectively; P = 0.0003) and flank (61.0 vs. 22.0% score 1; 35.6 vs. 57.6% score 2; and 3.4 vs. 18.6% score 3, respectively; P = 0.0001) HS more frequently than Holsteins, indicating that Jersey udders and flanks were overall cleaner than Holsteins. Jerseys may be better suited for compost-bedded pack barns than Holsteins based on the observed improvements in conductivity and hygiene scores.

Keywords: udder measurements, breed, SCC.