| dc.description.abstract | A study evaluating effects of metaphylaxis and milk replacer additives on
health and growth was conducted with Holstein bull calves (n = 52; mean BW =
42.28 +- 3 kg) < 7 d of age. Calves were randomly assigned to receive tilmicosin
phosphate (TIL), ceftiofur crystalline free acid (CEF), or saline (CON). All calves
received a commercial milk replacer powder (25% CP, 20% fat), and within
metaphylaxis treatment, were randomly assigned to receive milk replacer with: 1) 4
g/d for 7 d and then 2 g/d for the next 14 d of an egg-based additive (PR); 2) 2 g/d of
96% betaine (BE); 3) both PR and BE (BP); or 4) no additives (NA). Calves were
housed in individual fiberglass hutches with ad libitum access to a commercial calf
starter and water. Body weight was recorded twice weekly and fecal scores (1=firm,
4=watery) were recorded daily for 54 d. Number of treatments per calf for scours,
incidence of respiratory symptoms, and febrile events were recorded on a daily basis,
and the cumulative incidence of each response was used as an index of morbidity.
All data were analyzed as a completely randomized design with a 3 X 4 factorial
treatment arrangement. Neither metaphylaxis, additives, nor their interaction affected
ADG (P>0.60); overall, calves gained .45 kg/d. Fecal scores were reduced by 39% for CEF compared to CON (P<0.01), but were not affected by additives.
Metaphylaxis influenced neither the incidence of fever (P>0.3), or respiratory
symptoms (P>0.2), nor were they reduced by additives. Overall, calves were treated
an average of only 0.39 times for respiratory symptoms and 0.66 times for fever.
Scours were not influenced by metaphylaxis (P>0.6), additives (P>0.5), nor their
interaction (P>0.8). Other than fecal score, metaphylaxis did not enhance
productivity or reduce morbidity in this study, but disease challenge may have been
mild. Feed additives influenced neither measures of health and performance nor did
the metaphylaxis and feed additive interaction. | en |
