The Effects of Metaphylaxis and Milk Replacer Additives on Health and Growth of Neonatal Holstein Bull Calves.
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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.
Holloway, Kenton S. (2009). The Effects of Metaphylaxis and Milk Replacer Additives on Health and Growth of Neonatal Holstein Bull Calves.. Master's thesis, Texas A&M University. Available electronically from