Intake and digestibility of nutrients during the grazing period in sheep on deferred marandu pastures with four initial heights

Abstract

The objective of this study was to verify the effect of reducing in pasture height at the beginning of the deferment period (PHBD) of Brachiaria brizantha cv. Marandu on nutrient intake and digestibility in sheep during winter. The combinations between average sward heights (15, 25, 35 and 45 cm) at the beginning of the deferment period and the times of sward use during the winter were evaluated; intake and digestibility evaluations were carried out at the beginning, middle and end of the grazing period, which lasted 90 days. The experimental design used was completely randomized, with three replications. The parameters evaluated were: intake and digestibility of dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) and potentially digestible dry matter (pDDM). The pDDM contents were similar in pastures kept with 15 and 25 cm, but higher than those observed in pastures with 35 and 45 cm at the beginning of the deferment period. The NDF contents were lower and the CP and NDF digestibility were higher in 15 and 25 cm deferred pastures than in 35 cm at the beginning of deferment period, except for pastures lowered to 45cm. The improvement in nutritional value of the forage apparently ingested by sheep, promoted by ISP reduction, did not result in a variation in pasture consumption by the animals. DMI, expressed as percentage of body weight (%BW), ranged from 1.10 to 1.63. At the beginning of the grazing period, higher values of pDDM, CP and DM digestibility (DMD) were verified in simulated grazing samples. The same response pattern observed for nutritional value traits also occurred for DMI (g.day-1 and %BW) and CP intake. These were higher at the beginning, than at the middle and end of the grazing period. The use of lower sward heights at the beginning of the deferment period allowed the production of pasture with better nutritional quality, but these changes in the nutritional value of the pasture were insufficient to result in higher nutrient intake and digestibility. Furthermore, there was a reduction in nutritional value of the forage apparently consumed by sheep, in the intake and digestibility of deferred pastures throughout the grazing period, in winter. The lower pastures at the beginning of the deferment period (15 cm) improves the nutritional value of forage and nutrient digestibility at the beginning of the winter grazing period. The nutritional value and intake of deferred forage by sheep are compromised by the grazing period.

A estratégia de rebaixamento do pasto antes do diferimento modifica a eficiência de pastejo de ovinos no inverno

“…Regarding this relationship, the consumption and performance of sheep were not influenced by LSs, in contrast to our hypothesis. A similar result was presented by Silva et al (2021), evaluating the intake and digestibility of nutrients in sheep on stockpiled grazing of Marandu grass with different initial heights (15, 25, 35 and 45 cm). Pastures stockpiled with 15 and 25 cm showed a higher DMpd, CP and NDF digestibility and lower NDF content at the beginning of the grazing period compared to taller stockpiled ones.…”

“…In pasture sheep production systems, one of the main limitations is the lack of forage planning, which results in a forage shortage in the winter. In this context, a relatively easy strategy that guarantees the stock of forage mass in winter is stockpiling, which consists of selecting certain areas of pasture and excluding them from grazing to provide forage accumulation to be offered under grazing in the period of scarcity ( J. G. Silva et al, 2021).…”

Nutritional and metabolic parameters of sheep on deferred pasture with different strategy changes during the dry season

“…Furthermore, changes in protein and energy metabolites throughout the dry season indicate the need for differentiated supplementation for phases this period. In other words, to reduce problems arising from the loss of nutritional value of pasture and with consumption reduction by animals during the winter grazing period, an appropriate strategy is to use feed supplements, concentrated or forage, differentiated over the grazing period (Silva et al, 2021).…”