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

The diploma thesis prepares the evaluation of the feed ration during the period of plant nutrition of calves in the monitored enterprise. The feed is evaluated on the selected farm on the basis of nutrient needs with respect to the recommended values - standards. Above the award, the feed for the heifers is evaluated. In the case of heifers, the feed dose, which is presented during the rearing of heifers, is compared with the average daily increments of one year (2017).

Made available in DSpace on 2015-03-26T14:02:16Z (GMT). No. of bitstreams: 1 texto completo.pdf: 710241 bytes, checksum: 4ae2321162f69d0466dfa2b74c54cf95 (MD5) Previous issue date: 2011-07-12 / This study used 60 Nelore calves, with average initial body weight of 285 kg. The treatments were: (MS) Mineral Supplement, SUP1 Protein-Energy-Mineral Supplement, being the source of non-protein nitrogen (NPN) slow-release urea, with average daily intake of 0.7% of body weight (BW) in dry matter (DM), SUP2 Protein-Energy-Mineral Supplement, being the source of NPN conventional urea with an average daily intake of 0.7% of the BW in DM. The type of experimental design used applied was randomizedPerformance and economic efficiency of calves in pasture of Brachiaria brizantha cv. Marandu during wet-dry transition subjected to different diets. blocks with three treatments and four replications. It was used the Duncan test for statistical analysis on the animals performance. There was a difference in the results of SUP1 and SUP2 compared with the MS, with average daily gains of 0.367 and 0.458 kg/animal/day for SUP1 and SUP2 respectively and 0.166 kg/animal/day for the MS (P<0.05). There was no difference in average daily gain (ADG) (P>0.05) between the SUP1 and SUP2. The animals supplemented with protein-energy-mineral supplementation had greater gains than those submitted to mineral supplement during the period of transition water-dry. There were positive economic results for all treatments, and the best results came from the calves that received the protein-energy supplementation (SUP1 and SUP2). The highest gross margin was observed for animals in the treatment SUP2, R$45.12 animal/period, compared to the control treatment, R$ 29.81 animal/period, suggesting that protein-energy supplementation promoted higher economic return. Thus, there was no statistical difference (p>0,05) between SUP1 and SUP2 to for weight gain and also for additional intake of CP and TDN, and the two treatments showed superior results to the SM. The SUP2 treatment was superior economically to SUP2 and SM and SUP1, as for it had higher gross margin left to the experiment. / Neste trabalho foram utilizados 60 novilhos Nelore inteiros, com média de peso corporal inicial (PCI) de 285 kg. Os tratamentos foram: SM suplemento mineral; SUP1 suplemento proteico-energético-mineral, sendo a fonte de nitrogênio não proteico (NNP) a ureia de liberação lenta (ULL), com ingestão média diária de 0,7% do peso corporal (PC) na matéria seca (MS); SUP2 suplemento proteico-energético-mineral, sendo a fonte de NNP a ureia convencional, com ingestão média diária de 0,7% do PC na MS. O delineamento utilizado foi o de blocos ao acaso, com três tratamentos e quatro repetições. Foi usado o teste de Duncan para análise estatística referente ao desempenho dos animais. Houve diferença nos resultados do SUP1 e SUP2, comparados com o SM, com ganhos médios diários de 0,367 e 0,458 kg/animal/dia para SUP1 e SUP2, respectivamente, e de 0,166 kg/animal/dia para o SM (P<0,05). Não ocorreu diferença no ganho médio diário (GMD) (P>0,05) entre SUP1 e SUP2. Os animais alimentados com a suplementação proteico-energético-mineral obtiveram ganhos superiores aos submetidos ao suplemento mineral, no período de transição água-seca. Houve resultados econômicos positivos para todos os tratamentos, e os melhores foram verificados em novilhos que receberam a suplementação proteico-energética (SUP2). A maior margem bruta foi observada nos animais do tratamento SUP2, R$45,12 animal/período, em relação ao tratamento controle, R$29,81 animal/período, sugerindo que a suplementação proteico-energética possibilitou maior retorno econômico. Assim, não houve diferença estatística (P>0,05) entre SUP1 e SUP2 para ganho de peso médio, bem como para ingestão adicional de PB e NDT; os dois tratamentos apresentaram resultados superiores ao SM. O tratamento SUP2 foi superior economicamente a SM e SUP1, pois deixou maior margem bruta ao experimento.