PS12-28. A Gut Environment Modifier in Antibiotic Treated Dairy Heifer Calves with Clinical Digestive or Respiratory Disease.

Abstract Neonatal diarrhea and bovine respiratory disease are leading causes of sickness and death in preweaned dairy heifer calves and are responsible for a large share of deaths and systemic antibiotic use on dairy farms. Sick heifer calves that lose weight or fall behind in weight gain and growth during this period are more likely to calve later, produce less milk in their first lactation, and leave the herd earlier than healthy herdmates. This creates losses from treatment costs, mortality, and long-term losses from reduced lifetime productivity. Symbiotic products which combine probiotics, prebiotics, and egg-yolk antibodies are used to support gut health and calf performance. However, previous work has focused on healthy or newborn calves, or after they have received a full course antibiotic treatment. There is limited information on how these products perform when used as an add on treatment at the onset of sickness and receiving systemic antibiotics. A randomized controlled field trial was conducted on a large commercial Holstein dairy in Arizona. Heifer calves 6-30 days old were enrolled at the time of first systemic antibiotic treatment for farm technician diagnosed digestive disease(n = 100) or respiratory disease (n = 100). Within each disease category, calves were randomly assigned to a gut environment modifier Achieve ® Pro (5 grams dissolved in milk replacer twice daily for 15 days) or a milk replacer placebo (5 grams of additional milk replacer). All other treatments followed the farm’s standard protocols. Calves were followed for at least 75 days from the start of the systemic antibiotics. Body weight and hip height were measured at enrollment (day 0) and every 15 days thereafter through day 75. Fecal Scores were recorded at days 0,15, and 30 after enrollment. Rectal temperature was recorded at days 0 and 15. Blood samples were collected at day 0 and again before day 50 of age, prior to the farm’s routine vaccine booster. Fecal samples were also collected at days 0, 15, and again before day 50 of age. Mortality was recorded throughout the follow-up period. From day 0 to day 75, average daily weight gain (ADWG) differed by treatment calves in the respiratory group. Respiratory calves that received the gut environment modifier had higher ADWG than respiratory control calves (0.748 vs. 0.674 kg/d; difference 0.074 kg/d; 95% CI: 0.003-0.145; P = 0.04) while ADWG was similar between treatments in the digestive disease group and in the overall study population. These results suggest that the growth utilization of an gut environment modifier can be beneficial to calf as soon as being diagnosed and treated with an antibiotic.