Effect of Holstein genotype on ex-vivo interleukin-1ß response to lipopolysaccharide (LPS), lipoteichoic acid (LTA) and heat-killed Gram-negative and Gram-positive bacteria.

Effects of Holstein genotype on interleukin-1ß response were assessed by ex-vivo stimulation of whole blood with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or sonicated, heat-killed Gram-negative or Gram-positive bacteria. Holstein genotypes were unselected Holsteins (UH, n = 14) not subjected to selection pressures since the mid-1960s and contemporary Holsteins (CH, n = 13). Milk yield of UH and CH cows differ by more than 4500 kg/lactation. Whole blood was mixed with 0.01 µg LPS, 10 µg LTA or 2.5 × 106 CFU of sonicated, heat-killed E. coli, K. pneumoniae, S. marcescens, S. aureus, S. dysgalactiae, or S. uberis per mL of blood and incubated (4 h, 37 °C). Plasma IL-1ß was quantified by ELISA and log10-transformed concentrations analyzed with a multivariate linear mixed effects model. Responses to bacteria were greater than responses to LPS or LTA. Responses to LPS, LTA and the Gram-negative stimulants were greater in UH than in CH cows while responses to the Gram-positive bacteria did not differ between Holstein genotypes. In both genotypes, strong correlations were detected among IL-1ß responses to the Gram-negative stimulants and to LTA. There were strong correlations among IL-1ß responses to the Gram-positive bacteria in CH cows but only between S. aureus and S. dysgalactiae in UH cows. The IL-1ß response to S. uberis was highly correlated with responses to all of the Gram-negative stimulants in CH cows but only with E. coli in the UH cows. The reduced immune response could make contemporary cows more susceptible to infection by Gram-negative bacteria. Results confirm selection practices since the mid-1960s have altered immune response in the Holstein, at least to Gram-negative bacteria, and validate the need for additional studies to further evaluate the impacts of these selection practices on immune function in contemporary Holsteins.

Association between hygiene scores and somatic cell scores in dairy cattle.

OBJECTIVE: To develop a simple system for scoring hygiene in dairy cattle and determine whether hygiene scores were associated with individual cow somatic cell scores (SCSs). DESIGN: Observational study. ANIMALS: 1,191 cows. PROCEDURE: With the aid of a chart containing line drawings and descriptive text, hygiene scores ranging from 1 (clean) to 5 (dirty) were assigned for 5 body areas: tail head, thigh (lateral aspect), abdomen (ventral aspect), udder, and hind limbs (lower portion). To determine repeatability, hygiene scores were assigned to 75 cows twice by 4 experienced evaluators. To determine accuracy and ease of use, hygiene scores assigned by 14 college students to 23 cows were compared with scores assigned by 2 faculty members. To determine association with SCSs, hygiene scores were assigned to each of 1,093 cows by a single observer. RESULTS: Mean correlation coefficients for hygiene scores assigned twice by 4 experienced evaluators were > or = 0.884, indicating high repeatability. Students indicated that the scoring system was easy to use, and mean correlation coefficient for student and faculty member scores was 0.804. Hygiene scores for the tail head, thigh (lateral aspect), and abdomen (ventral aspect) were not significantly associated with SCS. However, hygiene scores for the udder and hind limbs (lower portion) and udder-hind limb composite scores were significantly associated with SCS, with SCS increasing as scores increased. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the hygiene scoring system was repeatable, accurate, and easy to use. However, only hygiene scores for the udder and hind limbs and the udder-hind limb composite score were significantly associated with SCS.