Exigências nutricionais, frequência de alimentação e níveis de cálcio e fósforo para bovinos Holandês x Zebu em confinamento

• Autor(a) principal: Zanetti, Diego
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5820
• topic: Nutrição animal; Minerais na nutrição animal; Fósforo; Cálcio; Bovino - Alimentação e rações; Animal nutrition; Minerals in animal nutrition; Phosphorus; Calcium; Cattle - Food and feed; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

This work was developed in order to evaluate the feed intake, digestibility and performance of crossbred cattle fed in confinement at different frequencies with diets containing different levels of calcium and phosphorus; determine the nutritional requirements of energy, protein and macro minerals; and evaluate the effects on consumption estimates when reducing the number of samples of leftovers for laboratory analyses by grouping these samples in the total period of the confinement. For that were used 32 1&#8260;2 crossbred Gir x Holstein barrows, with mean 377.46 ± 49.4 kg of initial body weight. Initially, four animals were slaughtered and used as a reference to estimate the initial empty body weight (EBW) of the remaining animals in the experiment. 24 animals were used in a completely randomized factorial 2x3x2 design with two concentrate diet levels (30 and 60%), three frequency (full diet fed in the morning, at 8:00 am; roughage provided in its entirety in the morning and concentrate divided into twice, at 8:00 and at 16:00 hours; and feeding roughage and concentrate divided into two equal portions per day) and diets with or without inorganic sources of calcium and phosphorus. The four other animals were fed daily at maintenance level (1.1% body weight on dry matter). The roughage used was crushed sugar cane. At the end of 84 days all animals were slaughtered and samples from the carcasses and not carcass constituents were taken to determinate composition. Chapter 1: The dry matter (DM) and nutrients were not affected (P> 0.05) by feeding frequencies but were higher (P <0.05) for diets with 60% of concentrate. Supplementation with dicalcium phosphate affected only the consumption of phosphorus that was higher for supplemented diets. There was no effect of feeding frequency, supplementation with dicalcium phosphate or their interactions (P> 0.05) on the digestibility of diets constituents. Higher levels of concentrate provided higher average of daily gains and income from hot and cold carcass. In Chapter 2: The net (NEm) and metabolizable energy (MEm) requirements for maintenance were obtained by relating heat production (CP) and metabolizable energy intake (MEI) while the energy requirements for weight gain (NEg ) and net protein requirements for weight gain were obtained as a function of EBW and empty body weight gain (EBWG). The daily requirements of metabolizable and net energy for maintenance were 86.48 and 126.15 kcal / PCVZ 0.75 respectively. The requirements for net energy gain can be obtained by the equation: NEg = 0.0568 ± 0.0025 × × PCVZ0,75 GPCVZ1,095. The efficiency of use of metabolizable energy for maintenance and gain are 64 and 29.68%, respectively. The metabolizable protein requirement for maintenance is 4.14 g / BW 0.75. The net protein requirements for weight gain can be obtained through the equation PLg = 236.36 ± 30.06 × EBW - 19.84 ± 6.14 × ER. Third chapter: The relationship between the consumption of each mineral and it retention was expressed as a linear equation, and the intercept considered the requirement for maintenance of the mineral. Using the samples of the carcass and no carcass were determined the proportion of each mineral, determining the body content for each mineral expressed as a function of EBW. No variations in daily fecal and urinary excretions of phosphorus according to the supplementation with dicalcium phosphate were found. The absence of dicalcium phosphate supplementation in cattle diets in the finishing phase implies lower retention of calcium and phosphorus in the carcass. The absorption coefficients were 83.34, 77.21, 82.57, 40.27 and 92.25% for calcium, phosphorus, sodium, magnesium and potassium, respectively. The net daily maintenance requirements are 28.18, 10.31, 50.11, 25.86, and 91.67 mg / EBW for calcium, phosphorus, magnesium, sodium and potassium, respectively. Net requirements for calcium, phosphorus, magnesium, sodium and potassium for weight gain can be calculated respectively by the equations: Ca = × EBW (EBW-51.77 × 0.3023); P = EBWG × (30.87 × EBW-3459); EBW = mg × (0.865 × EBW-0.2133); In EBW = × (6.517 × EBW-0.3483); EBW = K × (4.06 × EBW-0.1875). It is concluded that the intake, digestibility of nutrients and performance were not affected by the feeding frequencies adopted or by the levels of calcium and phosphorus added, but were improved with increasing level of concentrate. About the sampling of leftovers, it is recommended to make a single composite sample for 84 days of confinement. The values and equations obtained for the requirements of crossbred Holstein × Zebu differs from that obtained by Br- Corte (2010), emphasizing that the number of animals with similar characteristics like those used are a small part of the database of this system.