Sward Structural Characteristics and Performance of Beef Heifers Reared under Rotational Grazing Management on Campos Grassland

This study aimed to evaluate the effect of two rest intervals on structural sward characteristics and productive performance of beef heifers reared on Campos grassland managed on rotational grazing. The treatments were two intervals between grazing of 375 and 750 DD (degree days), based on thermal cumulative sum for leaf expansion of native grasses belonging to two functional groups. The experimental design was a randomized complete block design with two treatments and three replications. The tested animals were beef heifers with initial age of 12 months and average weight of 185.2 ± 17.4 kg. Measures in the pasture were: herbage mass, mass of green leaf blades, stem mass, dead material mass and green leaf allowance. The 750 DD rest interval presented higher herbage mass (24%), higher green herbage mass and 19% more leaves in the canopy. This rest interval also presents a high proportion of dead material and stems in the sward structure. In the other way, the 375 DD rest interval presents better chemical characteristics, with 20% more crude protein in the hand plucking samples. Heifers’ dry matter intake was similar between the rest intervals (2.04% of live weight) and the bite mass was also similar (0.22 g DM per bite) but the animal performance was higher in the 375 DD rest interval. The stocking density showed similarity between treatments with an average of 875 kg/LW/ha. The live weight gain per area was higher in 40 kg/LW/ha (P = 0.117) for 375 DD rest interval, reaching 251 kg/LW/ha produced over the 149 experimental days. Based on these results, we can conclude that the treatment of shortest interval between defoliation gave the highest gain individual animals in warm seasons.

Productivity and Grazing Behavior of Ewes with Single or Twin Lambs Raised in Mixed Italian Ryegrass/White Clover Pasture in Southern Brazil

The aim of this study was to compare the area production and grazing behavior of single- and twin-rearing ewes kept on a mixed Italian ryegrass/white clover pasture. The herbage allowance was maintained at 12 kg DM/100kg live weight during the experiment, by continuous variable stocking management for 112 days (4 periods of 28 days). We measure the live weight gains, the area production and the body condition score of ewes and lambs. Animal behavior was observed on four occasions during which we evaluated whether the lambs were grazing near to or far from their mother. Live-weight output from the ewes and lambs, and net output (ewes and lambs) were calculated. Results showed that being irrespective of birth type, ewes had similar mean daily weight gains, although ewes with twin lambs presented a mean lower body condition score. Ewes live weight output/ha did not differ significantly among birth types, but twin lambs produced 98.2 kg (45%) more live weight gain/ha. Total net live-weight output (ewes + lambs) was 121.5 kg greater for twins than for singles. Ewes with twin lambs spent more time grazing and ruminating. Lambs increased the time they spent grazing in each successive period. Single lambs spent significantly longer time grazing within 12 m of their dams (near grazing). Analysis of far grazing times by the broken line method showed that growing lambs rapidly increase the time spent far grazing up to a live weight of 20.3 kg in both birth types, which occurs at 95.3 and 115.9 days of age for single and twins, respectively. The results indicate that twin lambs are more productive than singles, when evaluated per area unit of pasture.