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&lt;0.01), but were not affected by additives. Metaphylaxis influenced neither the incidence of fever (P&gt;0.3), or respiratory symptoms (P&gt;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&gt;0.6), additives (P&gt;0.5), nor their interaction (P&gt;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.

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Objectives of the study were to evaluate if calves fed 6 L of high protein milk replacer (HPMR; 1135 g/d, 28% crude protein (CP), 20% fat) had improved performance and health as compared to calves fed 4 L of a conventional milk replacer (CMR; 454 g/d, 20% CP, 20% fat) in heat stress and non heat stress environments. Holstein bull calves (n=52) <3 d of age were assigned to a 2 x 2 factorial trial based on initial BW, physical health score, and total serum protein levels. One half of each nutrition group was housed indoors with temperature control, non-heat stress (NHS) environment and one half was housed outside under a shaded barn in subjecting them to a heat stress (HS) environment. The study was conducted for 56 d from June 18 to August 13, 2010. Average thermal heat index (THI) was calculated for each day using the average of 24 recorded temperatures and relative humidity (RH%). The 56 d average, low, and high range THI for the HS was 79, 67, and 86, respectively, while THI for the NH was 69, 66, and 74, respectively. Weekly measurements of body weight (BW) in kg, body length (BL), hip width (HW), wither height (WH), heart girth (HG), and hip height (HH) in cm were collected and average daily gain (ADG) was calculated. Water consumption (WC) in mL and starter intake (SI) in grams was measured daily. Feed conversion (FC) was also calculated for each nutritional treatment and environment. Fecal scores (FS) of 1 to 4 (1=hard, firm, 2=soft, firm, 3=no form, and 4=watery) were recorded daily. Calves with a FS of >3 were considered to have diarrhea and required treatment. Respiration rates (RR) were recorded at 0630 (AM) and 1830 (PM) to monitor respiratory challenges while rectal temperatures (RT) were also measured using a digital thermometer daily in AM and PM to monitor febrile events. If RT was greater than 39.2 degrees C for NHS calves and 39.7 degrees C for HS calves, they were treated for febrile events (FE). Data was analyzed using PROC MIXED (SAS 9.2). HPMR had a greater (P &lt; 0.01) WH, HG, BL, HH, ADG, WC, and FS than the CMR (0.15 vs. 0.11, 0.37 vs. 0.28, 0.27 vs. 0.22, 0.21 vs. 0.14, 0.82 vs. 0.58, 4235 vs. 2656, and 2.05 vs. 1.73, respectively). HS had a greater (P &lt; 0.01) WC than NHS (4365 vs. 2526, respectively). CMR had a greater SI and FC (P &lt; 0.05) than HPMR (0.942 vs. 0.437, and 1.99 vs. 1.78, respectively). HS had a higher RT AM, RT PM, RR AM, and RR PM (P&lt;0.01) than NHS (38.87 vs. 38.77, 39.03 vs. 38.79, 35.79 vs. 32.77, and 55.73 vs. 38.57, respectively. Calves in NHS had a higher FE (P&lt;0.01) than the HS calves (6.24 vs. 2.33). There was no significant difference in growth parameters in HS or NHS in calves of like feeding strategies. The results show calves in HS experienced higher RT AM, RT PM, RR AM, and RR PM. The increased protein and energy fed to the HPMR calves resulted in greater FS and increased growth.

This study was conducted to determine water intake. Forty-four Holstein bull calves were evaluated to investigate the effects of starter intake, body weight, temperature and time to predict water intake. A model was developed using PROC GLM in SAS. Least square means separation were used to identify significant effects. Starter intake was a significant variable (P < 0.05) in predicting the water intake of a calf, especially after day 21 when starter intake and water intake were both increasing. Water intake was increased by calves with fecal scores of 1 and 2. However, water intake was significantly different for calves with fecal scores of 3 or 4 with a (P < 0.05) which had decreased water intake. The interaction between scours and fecal score were not significant. Water intakes significantly differ in calves that had scour and in calves not experimented scours.

The stimulation of appetite for solid food is of paramount importance in the financial success of an early calf weaning system. In the present study, two production trials suggested that the replacement of the rolled barley (RB) component of a calf starter diet, with molassed sugar beet pulp (MSBP) or lucerne meal (LM), stimulated appetite, particularly before weaning. Despite continued improvements in voluntary food intake (VFI) after weaning, dietary differences were reduced, with no significant differences observed. The optimum level of MSBP inclusion in a barley based diet appeared to be in the range of 0.15-0.25 of diet DM. All diets bar one containing 0.55 MSBP, produced live weight gains (LWG) in excess of 0.7kg/d. However, the relationship between LWG and VFI was considerably stronger for barley based diets than those based on MSBP or LM. Metabolic studies suggested two possible explanations for the reduced LWG response to VFI as MSBP or LM replaced RB: a) inefficiency in ruminal fermentation and/or b) reduced nitrogen (N) digestibility. The reduction in N digestibility was correlated with an increased proportion of N bound to the ADF matrix. Further studies suggested that a microbial population capable of complete cell wall degradation was absent in the rumens of young calves up to 3 months of age. The results suggested that the availability and quality of the N leaving the rumen was reduced as MSBP or LM replaced RB. It was unclear from the present studies whether increased diet buffering capacity or a preference for feedstuffs other than RB could explain the potential improvements in VFI. A method was derivised to measure the buffering capacity in the rumen fluid of young calves which showed that the total VFA are the principal chemical component of the buffering system and the only rumen parameter found to make significant contributions to mathematical models accounting for variation in VFI. Rumen pH, although low, was not a regulator of VFI and accounted for only 0.03 of VFI variation.

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Our collective knowledge of calf nutrition has evolved over the past 100+ years, but there are still areas of improvement that merit further scientific inquiry. The work described herein explored different aspects of calf nutrition with a central focus on rumen growth and development. The first study performed used 8 Holstein bull calves to determine if calf starters differing in starch and neutral detergent fiber (NDF) content would affect calf growth, intake, rumen metabolites, blood metabolites, and gross rumen measurements when fed along with milk replacer (MR). The experiment used completely pelleted calf starters consisting of ground and pelleted barley, wheat, and corn grains. Besides the high-starch starter resulting in lower rumen pH, the hypothesis that completely pelleted calf starter diets differing in NDF and starch level would alter intake, growth, rumen metabolism, and rumen measurements was not supported. However, calves fed the high-NDF starter were $5.71 less expensive per calf to raise. Findings suggest a form of feed effect in today's calf starter diets that might be of physiological and economic importance. The second study tested custom-built rumen infusion, sampling, and evacuation devices. The main objectives were to build and confirm the successful use of the devices in one Holstein bull calf at 62 days of age, which determined a liquid passage rate out of the rumen at 40.2% of ruminal fluid/h. The third and final study examined the effects of form of diet (MR only, n = 5; MR and starter, n = 6) on rumen growth and development. More specifically, isocaloric and isonitrogenous diets were fed to neonatal and ruminally cannulated Holstein calves for 6 week. The hypothesis of MR and starter calves having altered gross rumen measurements, epithelial stem and progenitor cell number, and epithelial proliferation status was supported, but hypothesized changes in volatile fatty acid (VFA) transporter abundance and VFA absorption rate were not supported. These results indicate that form of diet, even one that promotes rumen growth, does not equate to enhanced ability to absorb VFA, but there is an effect on rumen stem and progenitor cells as well as epithelial proliferation. / PHD