Ganho de peso de novilhos mantidos em pastagem natural na encosta do sudeste do Rio Grande do Sul, recebendo níveis crescentes de suplementação energética

Abstract

RESUMO -O experimento foi desenvolvido com a finalidade de avaliar os efeitos de suplementação energética com sorgo moído sobre o desenvolvimento corporal de novilhos de corte em pastejo. Sessenta e cinco novilhos (12 a 15 meses de idade, sem raça definida, com 140 kg de peso vivo médio) foram mantidos em pastejo contínuo em uma pastagem natural melhorada com Lotus subbiflorus e invadida por Eragrostis planna, Ness. Os tratamentos consistiram de controle (T0), sem suplemento; 0,75% do peso vivo (T0,75); e 1,5% do peso vivo (T1,5) de grão de sorgo moído fornecido. Os animais foram distribuídos aleatoriamente nos tratamentos, segundo o delineamento completamente casualizado. Na média geral do experimento, houve efeito linear dos níveis de suplemento sobre o ganho de peso diário, de 0,36; 0,52 e 0,76 kg/animal/dia, respectivamente, para os tratamentos T0, T0,75 e T1,5. A suplementação energética permitiu maior ganho de peso nos animais suplementados em relação aos controle, durante todo o período experimental.Palavras-chave: ganho de peso, grão de sorgo, pastagem natural Increasing Levels of Energy Supplementation on Weight Gain of Grazing Steers Kept on a Natural Pasture at the Southeastern Region of Rio Grande do SulABSTRACT -The trial was conducted to evaluate the effects of energy supplementation with ground sorghum grain on grazing beef steers weight gain. Sixty five steers without definite breed, aging 12 to 15 months and weighing an average 140 kg of live weight were kept under set stocking on a natural pasture improved with Lotus subbiflorus. Treatments consisted of control or without supplement (T0); 0.75% of mean live weight (T0.75) and 1.5% of mean live weight (T1.75) of ground sorghum grain. Animals were randomly assigned to treatments according to a complete randomized design. Considering the overall mean of the trial, supplement levels showed a linear positive effect on daily weight gain, of 0.36, 0.52 and 0.76 kg/animal for T0, T0.75 and T1.5, respectively. Energy supplementation resulted in greater weight gains for supplemented animals compared to not supplemented animals, during all the experiment.

Quality of the forage apparently consumed by beef calves in natural grassland under fertilization and oversown with cool season forage species

“…In this study, this fraction of CP unavailable to the animal (ADIP) showed an average content of 35±7 g/kg DM (P>0.05).There is no indication of ideal values of ADIP, but it is usually between 40-70 g/kg DM. Fischer et al (2005) observed, during the spring in natural pasture improved with Lotus subbiflorus and invaded by Eragrostis plana, in southern Rio Grande do Sul, CP and ADF at concentrations similar to the present study in the same season: 175 g/kg DM and 358 g/kg DM, respectively.…”

“…However, Silva & Queiroz (2002) argued that the determination of ash gives only an indication of the richness in calcium and phosphorus in the analysis of feed, when it comes to products like bone meal and products of marine Fischer et al (2005), who found, in mid-September to November, high levels of mineral matter in natural pasture (322 and 148 g/kg DM), assigning these values to the contamination of samples after flooding of the area and subsequent deposition of dried mud on the forage. According to Alves et al (2008) the inorganic minerals include macro and trace minerals, while the organic matter is composed of carbon, hydrogen, oxygen, and in some cases, nitrogen.…”