Níveis de suplementação para fêmeas bovinas de corte em pastejo / Levels of supplementation for grazing beef cattle female

Carla Heloisa Avelino Cabral

This thesis was developed from four experiments with crossbred female with predominance of Zebu breed exposed to different levels of supply multiple supplementation on pasture. The objective of first experiment was to evaluate the effect of providing different levels of multiple supplement on the nutritional characteristics and productive performance of heifers on pasture during the rainy-dry transition period. It was used 30 crossbred heifers with predominance of Zebu breed at 19 months of age and body weight of 3035 kg in a completely randomized experimental design. Treatments consisted of mineral supplement (control treatment) and four levels providing 0.5, 1.0, 1.5, 2.0 kg/animal/day of multiple supplement with 300 g crude protein (CP)/ kg of dry matter (DM). There was quadratic effect of multiple supplementation (P<0.10) on daily weight gain (DWG). The intakes of DM and total digestible nutrients (TDN) showed increasing linear relationship (P<0.10) with multiple supplement levels, but there was no effect (P>0.10) on the intake digested NDF (DNDF) and DM apparent digestibility (DMD). There was no effect (P>0.10) of supplementation levels on the microbial nitrogen flow (MNF - g/day), but the microbial efficiency (MEF - CPmic g/kg TDN) and the relationship of microbial nitrogen flow with nitrogen intake (RMNF g/g nitrogen intake) were negative linear profiles. It is concluded that supplementation multiple optimizes grazing heifers performance during the rainy-dry season and supply 1.0 kg of multiple supplement per animal promotes the maximum increment of weight gain. The objective of second experiment was to evaluate the effect of providing different levels of multiple supplement on the nutritional characteristics and productive performance of heifers on pasture during the dry period. It was used 30 crossbred heifers with predominance of Zebu breed at 19 months of age and body weight of 3395 kg in a completely randomized experimental design. Treatments consisted of mineral supplement and four levels providing 0.5, 1.0, 1.5, 2.0 kg/animal/day of multiple supplement with 300 g CP/kg DM. There was in the least squares means trend stabilization of DWG the supply of 0.98 kg of multiple supplement. The intakes of DM and TDN showed increasing linear relationship (P<0.10) with multiple supplement levels. Linear-response-plateau relationships were observed between the coefficients of apparent digestibility of diet fractions and levels of multiple supplementation. The MNF showed positive linear profile for supplementation levels. It is concluded that supplementation multiple optimizes grazing heifers performance during the dry season and supply 1.0 kg of multiple supplement per animal promotes the maximum increment of weight gain. The objective of third experiment was to evaluate the effect of providing different levels of multiple supplement on the nutritional characteristics and productive performance of pregnant heifers on pasture during the dry period. It was used 24 crossbred heifers with predominance of Zebu breed at 32 months of age and body weight of 4165.74 kg in a completely randomized experimental design. Treatments consisted of mineral supplement and three levels providing 0.5, 1.0 and 2.0 kg/animal/day of multiple supplement with 300 g CP/kg DM. There was quadratic effect of multiple supplementation (P<0.10) on DWG. The intakes of DM and TDN showed increasing linear relationship (P <0. 10) with multiple supplement levels. The DMD had linear effect (P<0.10) with multiple supplementation levels. No effect (P>0.10) of levels of multiple supplementation on MNF and MEF, but the RMNF showed decreasing linear profile (P<0.10). It is concluded that the supply of 1.5 kg of multiple supplement optimizes the performance of grazing heifers during the dry season. The objective of fourth experiment was to evaluate the effect of providing different levels of multiple supplement on the nutritional characteristics and productive performance of pregnant cows on pasture during the dry period. It was used 28 crossbred cows with predominance of Zebu breed at body weight of 44611.6 kg in a completely randomized experimental design. Treatments consisted of mineral supplement and three levels providing 0.5, 1.0 and 2.0 kg/animal/day of multiple supplement with 300 g CP/kg DM. There was quadratic effect of multiple supplementation (P<0.10) on DWG and linear increase for final body condition score. The intakes of DM and TDN no effect (P>0.10) with levels of multiple supplement. The DMD had cubic effect (P<0.10) with multiple supplementation levels. No effect (P>0.10) of levels of multiple supplementation on the MNF and MEF, but the RMNF showed decreasing linear profile (P<0.10). It is concluded that the supply of 1.0 kg of multiple supplement optimizes the performance of grazing cows during the dry season.

Níveis de suplementação para fêmeas bovinas de corte em pastejo / Levels of supplementation for grazing beef cattle female

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