The effects of continuous and rotational grazing of sourveld on the quality of herbage selected by Simmentaler heifers

Seasonal changes in nutrient content under three defoliation treatments in two coastal grassland communities of Transkei

“…Temperature is the most important of these, causing a drop of 0.6-1.0% in DMD per 1°C increase in growth temperature (t'Mannetje 1984). Furthermore, as DMD improves in low quality herbage when levels of N and other minerals increase , seasonal trends in DMD should be positively correlated with those of CP and minerals, as demonstrated by Kreuter & Tainton (1989). However, in contrast to the results of Stanley-Price (1977) and Kreuter & Tainton (1989) there was no positive correlation between DMD and CP in the unburnt plots of this study.…”

“…Furthermore, as DMD improves in low quality herbage when levels of N and other minerals increase , seasonal trends in DMD should be positively correlated with those of CP and minerals, as demonstrated by Kreuter & Tainton (1989). However, in contrast to the results of Stanley-Price (1977) and Kreuter & Tainton (1989) there was no positive correlation between DMD and CP in the unburnt plots of this study. The consistency of a positive correlation between these has been questioned by the results of Dugmore et al (1986) However, examination of the results from both the unburnt plots and, in the second year, from the burnt plots (unaffected by fire), indicates that there was little change in DMD throughout the year.…”

“…The consistency of a positive correlation between these has been questioned by the results of Dugmore et al (1986) However, examination of the results from both the unburnt plots and, in the second year, from the burnt plots (unaffected by fire), indicates that there was little change in DMD throughout the year. Differences between the maximum and minimum values were rarely in excess of 10%, although such differences may be important in terms of animal performance (Kreuter & Tainton 1989). Peak values (25-28%) were attained in spring (September/October), but the timing of the lowest values (10-19%) was variable, falling between February and May.…”

“…Clipped samples provide only an estimate of sward quality since species and plant parts of differing quality are pooled. As such they are characteristically lower in CP and higher in fibre than fistula samples (Weir & Torrel 1959;Van Dyne & Heady 1965;Fourie et al 1986;Kreuter & Tainton 1989).…”

“…The same effect of grazing was recorded by Husband & Taylor (1932) and Roberts & Opperman (1966). Fourie et al (1986) suggested that as the stocking rate increased so did the CP of ingested herbage, as did Kreuter & Tainton (1989).…”