Efficiency of rumen microbial protein synthesis in cattle grazing tropical pastures as estimated by a novel technique

The efficiency of microbial protein synthesis (EMPS) in cattle grazing a range of tropical pasture types was examined using a new method of intra-jugular infusion of CrEDTA to estimate urinary excretion of purine derivatives (PD). Seven pasture types were studied in south-east Queensland, Australia, over a 13-month period. These included native tropical grass (C4) pasture (major species Heteropogon contortus and Bothriochloa bladhii) studied in the early wet, the wet/dry transition and the dry season; introduced tropical grass (C4) pasture (Bothriochloa insculpta) in the mid wet season; two introduced tropical legume species (C3), (Lablab purpureus and Clitoria ternatea); and the temperate grass (C3) pasture, ryegrass (Lolium multiflorum). There was a large range in EMPS across pasture types: 26-209 g microbial crude protein (MCP)/kg digestible organic matter intake (DOMI). Estimated rumen degradable protein (RDP) supply (42-525 g/kg DOMI) was the major factor associated with EMPS across the range of pasture types studied. EMPS in steers grazing all tropical grass pastures was low (<130 g/kg DOMI) and limited by RDP supply. Negative linear relationships (P<0.05) between EMPS and both neutral detergent fibre (NDF) and acid detergent fibre (ADF) concentrations in extrusa were evident. However, non-fibre carbohydrate in extrusa, total non-structural carbohydrate concentration in plucked pasture leaf, rumen fluid and particle dilution rate, protozoal concentration in rumen fluid and rumen fluid pH were not correlated with EMPS. It was concluded that EMPS was well below 130 g MCP/kg DOMI when cattle grazed unfertilised, tropical grass pastures in south-east Queensland and that RDP was the primary limiting nutrient. High EMPS was associated with very high RDP, vastly in excess of RDP requirements by microbes

Gulf of Carpentaria Developmental Finfish Trawl Fishery : Maximum Sustainable Yield

The Gulf of Carpentaria Finfish Trawl Fishery operates under developmental permits and harvests five main tropical snapper species. The fishery operates in eastern Gulf of Carpentaria waters and is managed by Fisheries Queensland on behalf of the Queensland Fishery Joint Authority. For the years 2004–2014, the fishery Total Allowable Commercial Catch (TACC) was fixed at 1250 t and substantially under-filled. In 2011 new stock analyses were published for the fishery. Results were presented to industry including the estimated equilibrium maximum sustainable yield (MSY) of 450 t for east Gulf of Carpentaria waters. The MSY value represented the maximum average combined species harvest that can be taken long-term; combining MSY harvests of the five main species. For the 2015 calendar year, a revised 450 t harvest quota was set for Crimson Snapper, Saddletail Snapper, Red Emperor and other Emperor species; plus a tonnage allowance for other permitted species. The revised quota tonnage represented a considerable reduction from the 1250 t set in previous years. Industry raised questions about not understanding how the MSY was arrived at and why it was less than early 1990s yield estimates. The purpose of this report is to explain the MSY estimates for east Gulf of Carpentaria waters. The 450 t MSY represents at present the best estimate available and is consistent with pre-2011 estimates.