<b>Biomass flows and defoliation patterns of alexandergrass pasture grazed by beef heifers, receiving or not protein salt

Abstract

ABSTRACT. The experiment aimed at evaluating leaf biomass flow, intensity and frequency of defoliation of Alexandergrass (Urochloa plantaginea (Link) Hitch) by beef heifers exclusively on pasture or that grazed and received protein salt. A completely randomized experimental design was used with repeated measures over time, two treatments and two area replications, with three Angus test heifers by paddock. Leaf blade intake flow is 18% superior for heifers exclusively on pasture. Grazing intensity (59.8%) is similar when heifers receive protein salt or not. Heifers receiving protein salt reduce by one day the defoliation frequency of tillers. The supply of protein salt for beef heifers grazing Alexandergrass affects the herbivore-plant relationship, decreasing intake flow and leaf blade defoliation frequency.Keywords: defoliation frequency, defoliation intensity, morphogenesis, Urochloa plantaginea.Fluxos de biomassa e padrões de desfolhação em papuã pastejado por bezerras recebendo ou não sal proteinado RESUMO. O experimento foi conduzido para avaliar os fluxos de biomassa foliar, intensidade e frequência de desfolhação em papuã (Urochloa plantaginea (Link) Hitch), pastejado por bezerras de corte exclusivamente em pastejo ou em pastejo e recebendo sal proteinado. O delineamento foi inteiramente casualizado, com medidas repetidas no tempo, dois tratamentos e duas repetições de área, com três bezerras testes da raça Angus por piquete. O fluxo de consumo de lâminas foliares é 18% superior quando as bezerras permanecem exclusivamente em pastejo. A intensidade de pastejo (59,8%) é semelhante quando as bezerras recebem sal proteinado ou não. Bezerras que recebem suplemento reduzem em um dia a frequência de desfolhação dos perfilhos. O fornecimento de sal proteinado para bezerras de corte em pastejo em papuã resulta em alterações na relação herbívoro-planta reduzindo o fluxo de consumo e a frequência de desfolhação de lâminas foliares.Palavras-chave: frequência de desfolhação, intensidade de desfolhação, morfogênese, Urochloa plantagine.

Biomass flow and defoliation pattern in alexandergrass fertilized with nitrogen

“…Also, the highest leaf expansion rate of Alexandergrass with 100 kg/ha N was also responsible for the increasing of leaf growth flow. Regardless of N dose applied, the growth flow of leaf blades was higher than that found in Alexandergrass (27.5 kg ha/day DM) by Eloy et al, (2014).…”

“…In Alexandergrass, this value does not allow early elongation of internodes and, consequently, prevents the quality reduction of forage as grazed (SALVADOR et al, 2014). Oliveira Neto et al, (2013 managed Alexandergrass pasture with FM around 3000 kg/ha DM, which allowed nutritional support for grazing heifers be mated at 18 months of age.…”

“…In Alexandergrass, the biomass flow and defoliation patterns can be altered by providing protein salt (ELOY et al, 2014). However, these flows are similar when beef heifers were supplemented with different frequencies (SALVADOR et al, 2014).…”

Leaf tissue flows and defoliation patterns of Alexandergrass grazed by heifers receiving energy supplement

“…The understanding of the effects of additional supplements given to herbivores and their ability to change the sward dynamics of pasture requires knowledge of growth, intake, and senescence of the forage species through study of leaf tissue patterns. Determination of biomass flows can be useful so that different supplementation strategies can be adopted in order to use grazing lands as efficiently as possible (Eloy et al, 2014).…”

“…In a study on Alexander grass, Eloy et al (2014) evaluated biomass flows and defoliation patterns and found no difference in defoliation intensity of leaf blades when the animals received mineral salt supplements or not. According those authors, the interval between two consecutive defoliations on the same tiller is longer (one day) when the heifers received protein supplements, as a result of substituting forage intake by supplement intake.…”