Maximising Lucerne (Medicago sativa) Pasture Intake of Dairy Cows: 2—The Effect of Post-Grazing Pasture Height and Mixed Ration Level

Abstract

The effects of lucerne (Medicago sativa) post-grazing residual pasture height on pasture utilisation (vertical and horizontal), pasture intake and animal production were investigated in a sub-tropical partial mixed ration dairy system. The study took place at the Gatton Research Dairy, Southeast Queensland (−27.552, 152.333), with a 26-day adaptation period followed by two 8-day measurement periods during August and September 2018. A quantity of 30 multiparous Holstein-Friesian dairy cows were offered two levels of mixed ration, 7 and 14 kg dry matter (DM)/cow/day for low and high levels respectively, and five levels of pasture allocation, to achieve decreasing residual pasture heights. Pasture allocations measured from 5 cm above ground level for the low mixed ration groups averaged 12.7, 15.9, 19.8, 35.3 and 49.2 kg DM/cow/day, and for the high mixed ration groups averaged 5.0, 8.3, 10.3, 18.6, and 25.2 kg DM/cow/day, respectively. As pasture allocation decreased, cows were forced to graze further down into the pasture sward, and therefore residual pasture height declined. Total intake (kg DM/cow/day) declined as residual pasture height (expressed as % of the initial height) declined, irrespective of mixed ration level, decreasing by 0.5 kg DM/cow/day for every 10% decrease in residual pasture height. Low total intakes were associated with high non-esterified fatty acid (NEFA) levels in plasma, indicating mobilisation of fat tissue to maintain milk production. In the high allocation treatments, an area of pasture remained ungrazed and cows were only grazing the top leafy stratum where pasture intake rate and intake were highest. Therefore, to maximise intake in sub-tropical partial mixed ration (PMR) systems, lucerne pasture should be allocated so that cows are always grazing the top leafy stratum. This can be achieved by ensuring the pasture around faecal patches remains ungrazed.

Maximizing Lucerne (Medicago sativa) Pasture Intake of Dairy Cows: 1-the Effect of Pre-Grazing Pasture Height and Mixed Ration Level

“…In this current study, the highest intake irrespective of mixed ration level was achieved when the pre-grazing pasture height was tallest, 39 cm above ground level. Therefore, within sub-tropical PMR dairy systems, lucerne pasture should be allocated to ensure PUP does not reach 0% [8] (also see the companion paper in this special issue [28]), at a pre-grazing height not less than 39 cm to maximise intake when the mixed ration allocation ranges from 33% to 67% of the total diet.…”

Nitrógeno no proteico de liberación controlada y Levadura Saccharomyces cerevisiae en vacas lecheras

“…Esos resultados se hallan relacionados a lo determinado en recientes investigaciones, donde se han encontrado incrementos significativos incluso mayores al 11% en la digestibilidad de la fibra (FDN) con dietas adicionadas con la levadura, ofrecida a novillos (Ison, et al, 2020). Por otro lado, respecto a estos resultados es necesario resaltar que la levadura opera de la misma manera tanto en el rumen del ganado de engorda que en el de las vacas lecheras.…”

The defoliation dynamics of a stockpiled native grassland pasture follow similar patterns between supplemented and unsupplemented beef calves

“…Experiments carried out on cultivated pastures showed a significant decline of HDMI with high horizontal utilization levels of the upper leaf stratum by cattle (Benvenutti et al, 2015(Benvenutti et al, . 2017Ison et al, 2019Ison et al, , 2020 where cattle grazed the lower strata of a pasture only when the top stratum became heavily depleted (Benvenutti et al, 2015). Specifically, on native rangelands HDMI decreases with high levels of horizontal utilization of the upper leaf stratum horizon of preferred plant species (Benvenutti & Poppi, com.…”