Table 1.
Variables tested for univariate association with the incidence of initial respiratory morbidity counts, in 122 pens of cattle on 102 feedlots. Variables with P < 0.2 were offered to a multivariable negative binomial model assessing feedlot management, cattle attributes, and vaccination practices
| Factor | Percentage of pens (# pens) or Median (10th & 90th percentile) | Coefficient | P-value |
|---|---|---|---|
| Pen level | |||
| Feedlot management | |||
| Yearly placements | 17 609 (2500, 62 000) | +0.000005 | 0.04 |
| Use same pens for receiving and shipping | 78% (96) | +0.25 | 0.21 |
| Veterinary use | Veterinarian on staff 4% (5) | Referent | |
| Private veterinarian regular visits 46% (56) | +0.77 | 0.02 | |
| Private veterinarian as needed 50% (60) | +0.73 | 0.02 | |
| Cattle attributes | |||
| Feedlot arrival — quarter of year (no placements in second quarter) | First quarter (Jan–Mar) | Referent | |
| Third quarter (July–Sept) | −1.3 | 0.001 | |
| Fourth quarter (Oct–Dec) | +0.77 | 0.001 | |
| Number of cattle in pen | 144 (72, 283) | −0.004 | 0.00 |
| Pen density (square feet/animal) | 238 (107, 469) | −0.002 | 0.00 |
| Cattle entry weight | 737 (563, 883) | −0.006 | 0.00 |
| Average miles transported | 180 (12, 900) | +0.0009 | 0.00 |
| Mass treated (metaphylaxis of all cattle in the pen with antibiotics to prevent respiratory disease) | 7% (9) | +0.9 | 0.00 |
| Cattle sex | Steers 60% (74) | Referent | |
| Heifers 30% (37) | +0.9 | 0.00 | |
| Mixed groups 10% (12) | +1.8 | 0.00 | |
| Cattle from multiple origins | 14% (17) | +0.4 | 0.02 |
| Cattle preconditioned | 31% (38) | +0.18 | 0.2 |
| Treated for internal parasites | 87% (107) | +0.14 | 0.12 |
| Treated for external parasites | 80% (98) | +0.21 | 0.004 |
| Week on feed (1–12) | −0.27 | 0.00 | |
| Vaccination practices | |||
| Received initial vaccine on arrival (within 3 d) | 78% (95) | +0.89 | 0.01 |
| Received initial vaccine (within 3 d) of any type by agent | |||
| BVDV | 68% (83) | +0.61 | 0.09 |
| IBRV | 75% (92) | +0.92 | 0.01 |
| BRSV | 56% (68) | +0.62 | 0.04 |
| PI3V | 58% (71) | +0.50 | 0.10 |
| Pasteurella (Mannheimia) haemolytica | 22% (27) | +0.65 | 0.02 |
| Haemophilus somnus | 26% (32) | +0.04 | 0.89 |
| Received initial killed vaccine (within 3 d): | |||
| BVDV | 14% (17) | +0.73 | 0.03 |
| IBRV | 10% (12) | +0.72 | 0.10 |
| BRSV | 8% (10) | +0.99 | 0.01 |
| PI3V | 10% (12) | +0.66 | 0.11 |
| Pasteurella (Mannheimia) haemolytica | 7% (9) | +0.66 | 0.03 |
| Haemophilus somnus | 10% (12) | −0.02 | 0.95 |
| Received initial modified live vaccine (within 3 d) | |||
| BVDV | 55% (67) | +0.03 | 0.92 |
| IBRV | 65% (79) | −0.02 | 0.95 |
| BRSV | 48% (59) | +0.14 | 0.66 |
| PI3V | 48% (59) | −0.09 | 0.77 |
| Pasteurella (Mannheimia) haemolytica | 15% (18) | +0.47 | 0.13 |
| Haemophilus somnus | 17% (21) | −0.004 | 0.99 |
| Revaccinated with any vaccine | 33% (39) | +1.1 | 0.00 |
BVDV — Bovine viral diarrhea virus; IBRV — Infectious bovine rhinotracheitis virus; BRSV — Bovine respiratory syncytial virus; PI3V — Parainfluenza 3 virus