Pasture herbage mass, quality and growth in response to three whole-farmlet management systems

Abstract

Abstract.The effects of different whole-farm management systems were explored in a farmlet trial on the Northern Tablelands of New South Wales, Australia, between July 2000 and December 2006. The three systems examined were first, a moderate input farmlet with flexible grazing on eight paddocks considered 'typical' of the region (farmlet B), a second, also with flexible grazing on eight paddocks but with a high level of pasture renovation and increased soil fertility (farmlet A) and a third with the same moderate level of inputs as farmlet B but which practised intensive rotational grazing on 37 paddocks (farmlet C).The changes in herbage mass, herbage quality and pasture growth followed a seasonal pattern typical of the Northern Tablelands with generally higher levels recorded over spring-summer and lower levels in autumn-winter but with substantial differences between years due to the variable climate experienced. Over the first 18 months of the trial there were no significant differences between farmlets in total herbage mass. Although the climate was generally drier than average, the differences between farmlets in pasture herbage mass and quality became more evident over the duration of the experiment. After the farmlet treatments started to take effect, the levels of total and dead herbage mass became significantly lower on farmlet A compared with farmlets B and C. In contrast, the levels of green herbage were similar for all farmlets.Throughout most of the study period, pastures on farmlet A with its higher levels of pasture renovation and soil fertility, had significantly higher DM digestibility for both green and dead herbage components compared with pastures on either of the moderate input systems (B and C). Thus, when green herbage mass and quality were combined, farmlet A tended to have higher levels of green digestible herbage than either of the other farmlets, which had similar levels, suggesting that pasture renovation and soil fertility had more effect on the supply of quality pasture than did grazing management. This difference was observed in spite of the higher stocking rate supported by farmlet A after treatments took effect.Levels of legume herbage mass, while generally low due to the dry conditions, were significantly higher on farmlet A compared with the other two farmlets. While ground cover on farmlet A was found to be less than the other farmlets, this was largely associated with the higher level of pasture renovation. Generally, all three farmlets had ground cover levels well above 70% for the duration of the experiment, thus being above levels considered critical for prevention of erosion.A multivariate analysis showed that the main explanatory factors significantly linked (P < 0.01) with the supply of high quality herbage were, in decreasing order of importance, those related to season and weather, pasture renovation, grazing management and soil fertility. Measurements of net pasture growth conducted using a limited number of grazing exclosure cages on three paddocks per farmlet reve...

Grazing systems and worm control in sheep: a long-term case study involving three management systems with analysis of factors influencing faecal worm egg count

“…The large peaks of WEC in late spring and summer of November and December 2004 on farmlets A and B were both associated with losses of ewes with lambs with acute haemonchosis (4.7 and 5% of ewes on each of these farmlets, respectively). These results suggest that, while intensification of sheep grazing systems in the Northern Tablelands region is unlikely to provide substantial benefits in parasite control, nevertheless the higher levels of green digestible herbage provided by farmlet A (Shakhane et al 2013) enabled a substantially higher SR to be supported without incurring higher worm burdens than on farmlet B. On the other hand, farmlet C had significantly lower WEC and 8 7 6y 6x 6 5 4 3 2y 2x 2 1 8 7 6 5 4 3 2y 2x 2 1y 1x 1 17zii 17zi 17yii 17yi 17xii 17xi 17w 17 16y 16x 16 15y 15x 15 14y 14x 14 13yii 13yi 13y 13x 13 12yii 12yi 12y 12x 12 11y 11x 11 10y 10x 10 9y 9x 9 8y 8x 8 7y 7xii 7xi 7x 7 6yiii 6yii 6yi 6y 6xiii 6xii 6xi 6x 6 5yiii 5yii 5yi 5y 5x 5 4ziii 4zii ...…”

“…The improved level of control of worms on farmlet C was associated with significantly increased susceptibility to worm infection (Colvin et al 2012) and reduced animal productivity as shown by reduced liveweights (Hinch et al 2013a) and fat scores (Hinch et al 2013b) of livestock on this farmlet relative to those on farmlets A and B. The long rest periods and lower levels of soil fertility on farmlet C were found to be associated with lower levels of both legume and pasture digestibility within this farmlet (Shakhane et al 2013) and these are likely to have contributed to the reduced productivity.…”

“…The mean number of graze days were lower on farmlet A than on farmlet B, due presumably to the higher level of green digestible herbage (Shakhane et al 2013) and stocking rate (SR, Hinch et al 2013a) on this farmlet with both of these farmlets having substantially longer graze periods than on farmlet C. The lengths of the grazing rest periods were similar on both farmlets A and B but were some 50% longer on farmlet C. It should be noted that, as grazing on farmlet C was usually within 'cells', which were smaller than subpaddocks, the actual days of grazing on this farmlet were lower and the days of rest higher than indicated in Table 3. Fig.…”

Reflections on the concept, conduct and findings of the producer-led Cicerone Project

“…The climate experienced during the trial taught researchers a lot about the climatic realities of this area such as the frequent dry periods ) and the occasional bursts of pasture growth that were so short-lived that it was difficult to measure their effects (Shakhane et al 2013a).…”

“…Also of great interest to them were the importance of maintaining the legume component of pastures (Shakhane et al 2013a) as a source of protein needed for meat ) and wool products (Cottle et al 2013); the significant differences observed between farmlets, in spite of the years being relatively dry; and the challenges of getting sown pastures to persist long enough to be worthwhile investments (Behrendt et al 2013a).…”