Empirical models to quantify the nutritive characteristics of annual pastures in south-west Western Australia

Abstract

The objective of this paper is to quantify the magnitude of the major sources of variation, which affect in vitro digestibility (DMD) and concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF), and crude protein (CP) of annual pastures in Mediterranean-type climate zones. Four experiments were conducted in the south-west of Western Australia in 2006–07 and 2007–08, where the supply of nitrogen, phosphorous, potassium, or sulfur and pasture types were varied. Effects of seasonality, fertiliser application, pasture type, and site were analysed with an auto-regression maximum likelihood procedure. Temperature sum was used to explain the seasonal differences in DMD, CP, NDF, and ADF. Seasonality explained 82, 79, 79, and 62% of the total variation in DMD, NDF, ADF, and CP, respectively, with only an additional 5, 5, 6, and 24% being explained by the combined effects of site/management, fertiliser application, and pasture type. The differences in DMD, NDF, ADF, and CP, between sites, were 2.3–6.0%, 4.6–18.7%, 5.8–8.6%, and 1.5–17.4%, respectively. Pasture types differed by 6.6–9.5%, 9.0–11.4%, 3.1–6.1%, and 5.1–5.2% for DMD, NDF, ADF, and CP, respectively. The differences between sites and pasture types were markedly larger for CP, NDF, and ADF than for DMD. Fertiliser application did not affect nutritive characteristics, with the exception of N application rates on CP. It was concluded that the seasonality model captured nearly all of the temporal variation in DMD, NDF, and ADF but not in CP. The spatial variation in DMD was mostly determined by pasture type. By comparison, NDF and ADF were most strongly affected by grazing management, and CP by the availability of N.

Heifer nutrient intake during early- and mid-gestation programs adult offspring adiposity and mRNA expression of growth-related genes in adipose depots

“…Therefore, the difference in CP between the high-and low-protein diets was much greater than that of energy and the negative DIP balance for the low-protein diet group in both the first and second trimesters, which clearly demonstrates that protein intake was restricted. Although the difference in protein levels between the high (in excess of NRC requirements) and low (below NRC recommended requirements) treatment group diets was large, both the high and low treatment group diets had protein contents that are commonplace under Australia grazing conditions (Schut et al 2010). Thus, the diets used in the current study would be considered relatively normal for breeder herds grazing Australian pastures.…”

“…The crude protein contents of diets w4% (low) and 13% (high) on a dry matter basis and were representative of reported variations of 1-17% in legume-based pastures (Schut et al 2010). The two-by-two factorial design allowed investigation into the interaction effects of high and low levels of recommended dietary protein intake during gestation of the beef heifer.…”

“…Pasture protein content can vary tenfold throughout the year (Schut et al 2010). In northern Australia, protein supplementation of breeder herds is necessary to maintain body condition during the dry season (Bortolussi et al 2005), while in Southern Australia, breeder cattle often graze winter and spring pastures that provide greater than the recommended level of protein (Walsh & Birrell 1987).…”

Breeding objectives for sheep should be customised depending on variation in pasture growth across years

“…Changes in optimal management need to be accounted for when calculating how the profitability of a farm is influenced by changing traits of animals (Groen, 1989;Amer, 1994). In areas where sheep are produced in Western Australia, there are big differences between regions in the amount and variation of pasture growth within and between years (Rossiter, 1966;Schut et al, 2010). These differences between regions in pasture growth can affect the optimal management of livestock (Chapman et al, 2009;Young et al, 2011).…”

The effect of saline and non-saline soil conditions on yield and nutritional characteristics of some perennial legumes forages

“…These are plant characteristics, environmental factors and cultural practices. And among plant factors, species and variety have a significant position (Schut et al 2010;Panahi et al 2012). In the studies performed regarding the subject, it has been revealed that CP contents were different among forage species and even among varieties of the same species (Mlay et al 2006;Tavirimirwa et al 2012).…”